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Peaking Power: Prologue Peaking Power: Introduction Chapter 1: The Brayton Cycle Chapter 2: Time Line – Gas Turbine Technology Chapter 3: Gas Turbine Performance, Simplified Chapter 4: Sir Frank Whittle, Father of the Gas Turbine Chapter 5: Gas Turbine Planes, Trains and Automobiles Chapter 6: Rutland on the Leading Edge Chapter 7: The Fuel Regulator Chapter 8: Compressor Drives for the Industrial and Gas Pipeline Industry Chapter 9: Enter the Peaking Power Package Plant Chapter 10: The Great Northeast Blackout Chapter 11: The Long-awaited Frame 7 Chapter 12: The Mighty MS5002 Gas Turbine Chapter 13: Speedtronic™ Control and Protection Systems Chapter 14: The Arab Oil Embargo of 1973 – 1974 Chapter 15: Cogeneration and Combined Cycle Chapter 16: Computerized Control Systems Chapter 17: The Long Anticipated 7EA! Chapter 18: Conversions, Modifications & Upgrades Chapter 19: Metals, Ceramic Coatings & Cooling Chapter 20: F-Technology and Beyond Peaking Power: Epilogue
Peaking Power – Prologue Black Start – Prologue The study hall in Du Bois library was quiet in the din of autumn that evening in November, 1965. Such was life at the University of Massachusetts at Amherst, MA. Winter was rumored to be just around the next blustery bend. Mid-term exams wouldn‟t let me think about the Thanksgiving break coming later that month. I should have been studying at this hour of 5:30 pm. As I recall, a pretty blonde co-ed (unnamed here) captured my eyes and imagination. Unfortunately for me, I didn‟t have hers. So there I was day dreaming (not about thermodynamics, as I should have been), when all of a sudden the lights flickered in the expansive study hall with long tables and uncomfortable wooden chairs. A few moments later, the lights flickered again and went out to stay. There was no thunder and no lightening. What just happened? A buzz came over the room. A few seconds later, I heard a deep voice: “This is God speaking.” Everyone around me chuckled. Some wise guy, no doubt. “Due to lack of interest, today has been cancelled.” The laughs were louder now. It wasn‟t quite dark outside but everyone in the hall began loading books into their backpacks and making their way to the exits where emergency lights were dimly lit. Something definitely had happened. It wasn‟t but two years after another November event when President Kennedy had been assassinated, so I‟m sure some students, like I, had considered something ominous had happened. Or was it a Soviet nuclear attack in retribution to Kennedy‟s blockade of Cuba in October 1962? That was my first experience with blackout conditions. It wouldn‟t be the last. November 9, 1965 was the day that came to be known as The Great Northeast Blackout. States along the eastern seaboard went dark and stayed that way for a dozen hours. New York State was perhaps the darkest, as the power system collapsed from Niagara Falls near Buffalo to New York City. Long Island was blacked out as well. I learned many years later that a lone gas turbine generating plant in the town of Southampton, NY, on the eastern tip of Long Island, was the only one in the region with “black start” capability. That is, this power plant manufactured by General Electric (GE), could start on battery power using a diesel cranking engine. It could fire, warm-up and accelerate to full speed on #2 distillate fuel oil from a nearby storage tank. It took approximately eight minutes after an emergency start signal was initiated. The good news was, the turbine performed as expected. This little GE 12-megawatt generator was credited with restoring power to Long Island and eventually New York City. Little did I realize that day in fall of 1965 that a career in gas turbine field service engineering would be in my future. I was hired with General Electric the following year. After eighteen months in technical marketing training, I opted to change my career direction. I was hired in 1968 by their international service organization called General Electric Technical Services Company, better known by everyone in the business simply as GETSCO (pronounced Jets-co).
After a brief period in training on the new Field Engineering Program (FEP), I was sent to Chicago to assist in the installation of three 4-unit GE gas turbine power blocks. These twelve package power plants could start and operate on either natural gas or liquid fuel. Commonwealth Edison Company, at their Crawford Station, needed peaking power in case that region ever experienced a power emergency. Also, one of the Dresden nuclear plants was seriously behind schedule, so these units were immediately put into service for base load operation. At the time, they ran only on liquid fuel, as the gas fuel system was not commissioned until years later. A few months later, I was called back to Schenectady, NY to enter the Gas Turbine Start-up Program. The program lasted about one year. We were trained on current and new control systems. The current controls on MS5001LA gas turbines utilized the Young & Franklin fuel regulator. The first electronic system, first used on MS5001N gas turbines, was GE‟s Speedtronic™ Mark I. We were trained to provide start-up support on both systems. After the training period, in the May 1969, an emergency call came in from a site in Escuintla, Guatemala. No longer considered a trainee, I was dispatched to the capitol city and later driven down toward the Pacific side of the country. Along with another engineer, Willie Brandt (no relation to the former leader of Germany) and I were sent to a flooded region of the country to “bailout” two GE gas turbine generators. We were there for about a month. Torrential rains came every day and we had to cross over a river (sometimes by cable and a stirrup chair), to get to the power plants. This GE year-long start-up program gave me extensive controls and start-up experience on several assignments within the USA and overseas. Over my career, I‟ve worked in more than 20 countries for GE and a few countries more since then. It was the beginning of a 40+ year career in gas turbine field engineering. I dedicate this blog endeavor to all the friends and associates I have had in the gas turbine business and in particular, the field engineers and those associated with the Field Engineering Program (FEP). We call ourselves “Turbine Cowboys.” Visit www.turbinecowboy.com to learn more about the guys and gals who have become field engineers in the power generation business. Please read on and comment. - David Lucier Tags: gas turbines, turbines
Peaking Power – Introduction Black Start – Introduction Since its introduction toward the end of World War II in jet aircraft, the applications of gas (combustion) turbines have been myriad. Some uses have been successful, others have not. In most cases, the failures were not because of ill-conceived applications. More often it was a case where they were “ideas whose times had not yet come.” Note: For the most part herein, I will refer to these types of prime movers as gas turbines, even though some only burn liquid fuels. Also, some in the industry use the term combustion turbines, but my GE experience makes me prefer the word gas. Gas turbine applications in some industries were tried in earnest but never came to fruition. For instance, even though the Union Pacific Railroad gave gas turbine locomotives a good look by ordering a fleet of units from ALCO with GE engines in the late 1940s to propel cargo and passenger trains. However, high-frequency whining from the compressors limited their use to “open spaces” of the far western United States or Canada. Out in the plane states and mountains ranges, air-borne noise was less of an irritant to far away townships. What if compressor noise attenuation had been made an engineering design priority, using inlet silencing, would turbopowered trains then been allowed to pass through more densely populated city areas? Automobiles were another potential application in the 1950s and 1960s. A British company named Rover tried gas turbines in sedans and commercial vehicles. What if the Rover Jet One car had been victorious in road racing? Suppose the Rover BRM race car actually won the 24 Hours Le Mans race in 1965, defeating the Ferraris and Porsches instead of finishing a respectable tenth? Certainly gains in reducing fuel consumption made the Rover race cars more efficient when regenerators were installed in the turbine exhaust. Regeneration was used to recover the exhaust heat to pre-heat compressed air entering the combustor. Here‟s another scenario: Suppose the Granatelli-designed Studebaker gas turbine car, piloted by the famous racer Parnelli Jones, had actually won the Indianapolis 500 in 1967, instead of slipping to fourth place due to a minor gearbox component failure? Had this part not failed, having nothing to do with the gas turbine power plant and the turbine car taken the checkered flag, would turbinepowered vehicles (trucks and other long-distance carriers) become popular for cross-country transportation? In racing they say: “what wins on Sunday, sells on Monday!” Air travel was another thing in the 1950s. Former Pan American Airways CEO, Juan Trippe, favored jet-powered commercial airplanes and did much to propel a reluctant transportation industry. Trippe envisioned non-stop, international air travel. He forced the industry away from turbo-prop aircraft. This act of “arm twisting,” along with the fear of European competition, made companies like Boeing, Lockheed, General Electric and Pratt-Whitney develop jet engines for commercial aviation. Decades later, after the advent of such innovative aircraft as the Boeing 747 and the supersonic Concorde, the traveling public thinks nothing of hopping cross-continent airplane and even nonstop from New York to Beijing, a 14 hour trip. The gas turbine (jet) has been an obvious commercial aviation success story.
Note: I got to fly on one of the first Pan American 747 from Hong Kong to Tokyo in 1971. What a thrill that was. I had just spent 5 months installing two GE gas turbine PPP north of Saigon, Vietnam. It was a treat to fly on the maiden flight in the Far East. It took a couple of decades for gas turbine electric power generation to come into its own. Perhaps no event in history has had more impact on emergency electric power generation by gas turbines as The Great Northeast Blackout of November 1965.
Fig. I-1: Dark Days – Transmission Lines Suddenly “Darkened” During a Blackout Gas turbines with “black start” capability were in high demand for a decade thereafter. The bottom fell out in the USA, however, with the Arab Oil Embargo of the winter of 1973 and 1974. These two events form bookends for the history books for the highpoint era for gas turbine emergency power installations. For the next ten years, however, island countries of the Caribbean were not deterred. In the middle of the decade, the 20 megawatt GE frame 5 package power plant became very popular for its rating and quick response to needs of a region plagued by frequent hurricanes. The Bahamas, Virgin Islands, Aruba, Curacao and other islands placed orders with GE, Westinghouse and others. Oil-producting countries like Venezuela, Colombia and Mexico, ordered hundreds of GE frame 5 and Westinghouse 251 units. The impact of the gas turbine on power generation in the USA took another decade to recover. It wasn‟t until the advent of co-generation (co-gen) power plants in the early 1980s that gas turbines made a comeback as an alternative power sources. Co-gen plants were constructed next door to “steam hosts” like paper mills, salt plants and other industrial facilities. Combined-cycle (CC) plants became popular as well as in the 1990s. The electricity that was simultaneously produced was more of a byproduct in co-gen applications than a primary raison d‟etre. Furthermore, as efficiencies improved for combined-cycle plants of the 1990s, reaching targets above 50 percent, so gas turbines became the method of choice for many electric utility 5
companies and industrial plants. Siting for nuclear power, as well as coal-burning plants, took far longer to be realized, as compared to gas turbine generation. Nowadays, the reference has changed from co-generation to combined heat and power (CHP). So we come to these questions when we consider the gas turbine as a prime mover. What if can be a fun game to play, as follows: • What if… the problem of compressor noise had been resolved, permitting trains to operate in cities, would gas turbines have become common prime movers for trains? • What if… Rover gas turbine cars of the early 1950s proved to be a viable means of day-to-day transportation in England, would we all be driving turbine cars today? • What if… the Northeast Blackout of 1965 had been averted? Would GE and others have abandoned research and development of the gas turbine? • What if… the Rover BRM turbine-powered car won the 24-hour race at 1965 LeMans, would enduro-type cars be all gas turbine powered today? • What if… Andy Granatelli‟s gas turbine car actually won the Indy 500 in 1967? Would Indycar engines be all gas turbines today? I repeat here the adage in racing: “What wins on Sunday, sells on Monday.” • What if… the Arab-Israeli war had not resulted in the Arab Oil Embargo of 1973 – 1974? Would the OPEC countries have had far less influence on oil consuming countries today? Sometimes forces more powerful than just “good ideas” come into play. However, it is still fun to play What if… Tags: gas turbines, turbines
Peaking Power, Chapter 1: The Brayton Cycle Black Start, Chapter One: The Brayton Cycle The individual most commonly associated with the concept of the combustion (gas) turbine engine was an American named George Brayton (1830-1892). He was an engineer with vision and ingenuity, who conceived the gas turbine thermodynamic cycle back in 1872, when he filed for a patent. Discussions about gas turbines need to begin with Brayton. Brayton conceived an engine that compressed atmospheric air to a high pressure. In his concept turbine, the compressed air would then be mixed with a fuel (most commonly natural gas or #2 distillate oil) and ignited in one or more combustion chambers. The excess air (that is, air not needed in the combustion process) would then be used to dilute and reduce the high-temperature combustion gases to a more moderate level, without significantly reducing the pressure leaving the combustors. This would be known as combustion at constant pressure. In Fig.1 below, air from the atmosphere adjacent to the turbine is drawn in and compressed, as shown from point 1 to point 2. Notice that the volume decreases as the pressure rises. Heat is then added between points 2 and 3 on the graph. However, the pressure remains essentially constant, as represented by the horizontal line on this pressure-volume (P-V) diagram. Take a few minutes to study all aspects of the graph below. Pressure is on the vertical axis (ordinate); Air Volume is on the horizontal axis (abscissa). Notice how volume decreases as pressure increases along the up slope from Point 1 to Point 2. Trace the line from the Start Point 1 around to Point 4. Imagine how the pressure and volume change along the route. Notice where heat is added to the compressed air.
Fig. 1-1 Pressure Volume Diagaram for Brayton Cycle 7
Thereafter, the hot gases expand through stationary nozzle segments that direct the flow to impinge on the turbine blade surfaces (a.k.a. buckets) and develop torque (power). According to Brayton, power will be developed by the gases applying impulse forces on the turbine rotor blades. Additional power results from reaction forces of the hot gases accelerating away from the turbine blades. These TWO forces develop rotational power to turn turbine wheel(s). An extension shaft from the turbine wheels would then be connected to an electric generator or other load device to do useful work. Brayton envisioned that approximately 2/3 of the power developed by the gas turbine would be required to drive the turbine‟s own axial-flow compressor and such required auxiliaries as fuel, oil, hydraulic and water pumps. Finally, the exhaust gases would then be sent to a diffuser (to reduce the flow velocity) and out to the atmosphere through a stack enclosure. The Brayton Cycle is considered to be an open system, since the exhaust gases are expelled back to the atmosphere from whence they originated. Please refer to Fig. 2 below.
Fig. 1-2 Gas Turbine and the Brayton Cycle
The stick diagram (Fig.1-2 above) and the associated pressure-volume diagram (Fig. 1) clearly show the gas turbine in its most rudimentary form. The four numbered corner points show following modes:
Points 1 to 2: Compression (air drawn from atmosphere and compressed) Points 2 to 3: Combustion (combustion at essentially constant pressure) Points 3 to 4: Expansion (expansion across turbine section) Points 4 to 1: Exhaust (exhausting hot gases back to atmosphere)
The Brayton Cycle, in its simplest form, is not particularly complicated. However, it took almost 60 years before working engines were developed. This was due, in large part, to the fact that Brayton‟s idea was one whose time had not yet come. Technology lagged behind his concepts because the need was not yet beckoning for such a device as a gas turbine. The axial-flow compressor requires work to compress the air (W1-2) as shown in Figure 1-1. Energy, in the form of fuel (natural gas or #2 distillate oil are the most popular), is injected into the combustor(s) shown as Q2-3. The output work developed between W3-3’ is required to power its own compressor and auxiliaries. The remaining power (W3’-4) is used to drive a load device (generator or load compressor). The gases going to the atmosphere are hot, but this is often wasted energy (Q4-1), unless heat recovery equipment is employed. Figure 1-3 below shows gas turbine operation for three different ambient conditions: an ISO day (compressor inlet temperature of 59 ˚F day, which is 15˚C) is represented by the sloped line in the middle. To the left is the characteristic control line for a MAXIMUM ambient day (assume something like 100 ˚F at the compressor inlet). The third line shows a loading curve for MINIMUM ambient day (assume 32 ˚F at the inlet).
Fig. 1-3 Base and Peak Load Operation for 3 Ambient Days 9
Loading the gas turbine from No Load to Rated Load for the ISO day, the fuel flow and exhaust temperature would track along the center line until the BASE load limit is reached.
If PEAK load is then selected, the curve would track higher to intercept the upper line. On a MAXIMUM ambient day (hot), the governor control would track along the line on the left until BASE or PEAK load was intercepted, as desired. Similarly, a MINIMUM ambient day (cold) is reflected in the governor tracking along the right-side line to BASE or PEAK load. Notice that a different BASE load level is achieved depending upon the ambient day of operation. For instance, suppose the outside temperature at the compressor inlet is 32 ˚F, more power would be developed than on an ISO (59 ˚F) day. Much more power would be developed on a 32 ˚F day than on a MAXIMUM (say 100 ˚F) day, but fuel costs will increase too.
There are some minor efficiency gains on colder days, but for the most part this additional power is developed as a consequence of more fuel being burned in the combustors. This raises the pressure acting on the turbine blades (buckets). It costs the gas turbine operator more in fuel for the additional power generated. However, the cost per kilowatt generated decreases. George Brayton never lived to see his concept engine, the gas turbine, become a reality. If he lived today, the F-class gas turbines that develop upwards of to 200 megawatts would likely bring a grin to his face some 14 decades later. Tags: Brayton Cycle, Combustion, Compression, Exhaust, Expansion, gas turbines, George Brayton, Pal Engineering, turbines
Peaking Power, Chapter 2: Time Line – Gas Turbine Technology Chapter Two: Time Line – Gas Turbine Technology 150 BC – A Greek philosopher and mathematician, Hero, invented a toy (called an aeolipile) that rotated on top of a boiling pot of water. This caused a reaction effect of hot air or steam that moved several nozzles arranged on a wheel. This works when one understands the Third Law of Motion – Every action produces a reaction, equal in force and opposite in direction. 1232 – Chinese began to use rockets as weapons. The invention of gun powder uses the reaction principle to move rockets forward. 1500 – Leonardo da Vinci drew a sketch of a device called the chimney jack, which rotated due to the effect of hot gases flowing up a chimney. It looked like a device that used hot air to rotate a spit. The hot air came from the fire and rose upward to pass through a series of fan like blades that turned the roasting spit. 1629 – Giovanni Branca developed a stamping mill that used jets of steam to rotate a turbine that then rotated to operate machinery. 1678 – Ferdinand Verbiest built a model carriage that used a steam jet for power. 1687 – Sir Isacc Newton announces the three laws of motion. These form the basis for modern propulsion theory. 1791 – John Barber received the first patent for a basic turbine engine. His design was planned to use as a method of propelling the „horseless carriage.‟ The turbine was designed with a chaindriven, reciprocating type of compressor. It had a compressor, a combustion chamber and a turbine. 1872 – Dr. F. Stolze designed the first true gas turbine engine. His engine used a multistage turbine section and a flow compressor. This engine never ran under its own power. 1903 – Aegidius Elling of Norway built the first successful gas turbine using both rotary compressors and turbines - the first gas turbine that actually delivered excess power. 1897 – Sir Charles Parson patented a steam turbine which was used to power a ship. 1914 – Charles Curtis filed the first application for a gas turbine engine. 1918 – Dr. Stanford A. Moss developed the GE turbo-supercharger engine during W.W.I. It used hot exhaust gases from a reciprocating engine to drive a turbine wheel that in turn drove a centrifugal compressor used for supercharging. General Electric Company started a gas turbine division.
1920 – Dr. A. A. Griffith developed a theory of turbine design based on gas flow past airfoils rather than through passages. 1930 - Sir Frank Whittle, in England, patented a design for a gas turbine for jet propulson. The first successful use of this engine was in April, 1937. His early work on the theory of gas propulsion was based on the contributions of most of the earlier pioneers of this field. The specifications of the first jet engine were:
Airflow = 25 lb/sec Fuel Consumption = 200 gal/hr or 1300 lb/hr Thrust = 1,000 lb (estimated) Specific Fuel consumption = 1.3 lb/hr/lb
Fig. 2-1 Sir Frank Whittle and his Jet Engine Prototype 1936 – At the same time as Frank Whittle was working in Great Britain, Hans von Ohian and Max Hahn, college students in Germany, developed and patented their own engine design. 1939 - Ernst Heinkel Aircraft flew the first flight of a gas turbine jet, the HE178. 1941 - The 2nd World War and the need for faster flying aircraft changed all that. However, the development of aero-derivative engines had to evolve as well. But the war wouldn‟t wait. Not only that, it ended before the Allied Forces (in particular, England and a brilliant engineer named Frank Whittle) could get its jet-powered aircraft aloft.
The Americans never got fighter planes in the air before the allied victories in Europe and Japan. However, when the war economy evolved into an industrial economy in the late 1940s, the conversion of the jet engine to other applications (air, land, rail and sea) followed and the result was the combustion (gas) turbine. 1942, April 11 - David Lucier is born. Little did anyone know at birth that his destiny was to have a career in field engineering services in gas turbine technology, since he was more interested in sucking on a warm bottle of milk. He didn‟t invent a single thing in his lifetime. He did, however, service many GE gas turbines throughout the world during a 40+ year career.
Fig. 2-2 Older brother Stephen and Fat David (age 8 months in 1942) 1942 – Dr. Franz Anslem developed the axial-flow turbojet, the Junkers Jumo 004, used in the Messerschmitt Me 262, the world‟s first operational jet fighter. After World War II, the development of jet engines was directed by a number of commercial companies. Jet engines later became the most popular method of powering airplanes. 1949 – General Electric, of Schenectady, NY sold gas turbine locomotive engines that were installed on ALCO (from the same city) trains for the Union Pacific Railroad.
Fig. 2-3 Gas Turbine Powered Locomotive 1951 – General Electric sells three gas turbine generator drives, dual fuel (#2 distillate and #6 heavy oil) rated at 5,000 KW each were installed at Central Vermont Public Service in Rutland, VT. Units were nicknamed the “Kilowatt Machines.” The power plants were intercooled, regenerative cycle that operated at base load. Dave Lucier assisted in troubleshooting a problem in 1988 and was later given the Young & Franklin fuel regulator (serial number 49) and the plant nameplate from Unit #1, for his service help. The last of the three units were retired in 1989 and sold for scrap.
Fig. 2-4 Kilowatt machine at CVPS in Rutland, VT (1951) 1953 – General Electric sells two frame 3 gas turbine generator drives, dual fuel (natural gas and #2 diesel), with on-line, auto transfer, to Montana Dakota Utilities in Williston, ND. Units are still in operation as of 2010. Rating 4,000 KW for each.
Fig. 2-5 Montana Dakota Utilities MS3001 Gas Turbine at Williston, ND (1957) 1957 – General Electric sold their first frame 3 steam turbine and gas (STAG) plant to the City of Ottawa, KS. In 2010, the unit is still operational. Dave Lucier’s company, PAL Turbine Services, LLC, conducts borescope inspections in October 2010. 1965, November 6 – The Great Northeast Blackout. MS5001D Package Power Plant (PPP), installed at Long Island Lighting Company plant in Southampton, NY, is credited for restoring power on the island, feeding back to New York City. GE begins selling the PPP design and 4unit Power Blocks like “hot cakes.” Hundreds are shipped in the next 5 years.
Fig. 2-6 Black Out Along NY State Transmission Lines (1965) 1966, September – David Lucier graduates (finally) from the University of Massachusetts, Amherst. His mother is pleased. Lucier begins work for General Electric on the Technical Marketing Program (TMP) in the Power Transformer Department in Pittsfield, MA. He is unhappy living at the YMCA. His mother is happy he doesn‟t quit GE because he needs “a job to pay off his college loans.” 1967, June – David Lucier is offered a transfer assignment on the TMP to the Gas Turbine Department in Schenectady, NY. With practice, Lucier learns how to spell the name of the city. He likes gas turbines, but a friend with a brand new black 1969 Corvette convinces him that a working at a field engineer (What‟s that?) might be a wise career change. The Corvette was a motivator for Lucier. 1968 – David Lucier changes careers and enters the GE Field Engineering Program (FEP). He is sent to help install three 4-unit power blocks at Crawford Station for Commonwealth Edison Co. in Chicago, IL. The twelve turbines were GE MS5001L package power plants (PPP) rated at 15.000 kilowatts each at NEMA conditions. Lucier likes working as a field engineer because of several factors 1. 60-hour weeks that include 20 hours of paid overtime (Lucier begins paying off his college loans making his mother happy!). 2. Expense account with a daily per diem for food. He likes eating sirloin steak.
3. Rental car was a 1968 Dodge Charger (Avis mistake). Lucier refuses to surrender the car until the concludes. 4. Some beautiful women in Chicago for Lucier to meet and enjoy
Fig. 2-7 Lucier traveling to work on a flooded gas turbine site in Guatemala (1969) 1968 – David Lucier is assigned to the Gas Turbine Start-up Program and begins a 40+ year career in field engineering services. He worked for General Electric Technical Services Company (GETSCO) for about 5 years in his first field career. Lucier is sent to work abroad on gas turbines in over 20 countries. In 1971, Lucier is reassigned as Area Engineer for Venezuela, Colombia and Caribbean Islands including Aruba, Curacao and Isla Margarita. His first field career ends in June 1973.
Fig. 2-8 Lucier and associates at power plant in Vietnam (1971) 1971 – GE produces first MS7001A gas turbine Package Power Plant. First unit shipped to Long Island Lighting Company in Babylon, NY. It was one of the first gas turbines with Speedtronic™ Mark I and electro-hydraulic fuel controls.
Fig. 2-9 Lucier at power plant in Venezuela (1972) 1973 –1974: The OPEC Oil Embargo. Members of oil-producing nations create a world-wide crisis that lasts many months, driving up costs for gasoline and heating oil.
Motorists and home owners in the USA experience fuel shortages and gas stations limit hours of operation. Some stations limit sales to just $1.00 worth of gasoline per visit. Also, alternating days (odd-even license plates) become common in some states like Massachusetts. Significant reduction in demand for gas turbine power plants in the USA begins and lasts over the next decade. However, OPEC nations in the Middle East and Caribbean Islands still order PPP from GE for their specific applications.
1982 – GE introduces a cogeneration (Co-Gen) plant using the new MS6001 gas turbine. The so-called frame 6 turbine was a hybrid design between the frame 5 and 7. It had a 17-stage compressor like the frame 5 and a 3-stage turbine like the frame 7. The first units have Speedtronic™ Mark II controls. The turbine was exhaustively tested at the Schenectady Plant Outdoor Test Site (dubbed SPOTS) in the early 1980s. Later in the decade, the Mark IV 19
computer-based control systems are introduced. Co-Gen nowadays is known as Combined Heat and Power (CHP) in the industry. 1983 – 1988 – GE begins to install STAG plants worldwide. STAG stands for steam turbine and gas. These plants use either the new MS7001E (60 cycle generators) or MS9001E (50 cycle generators). Fourteen STAG-109E gas turbine plants, totaling 2,000 MW of power, go into commercial operation for Tokyo Electric Power Company (TEPCO) in Futsu, Japan in 1988. At the time, this site was the largest gas turbine installation of its kind in the world. These turbines began with Speedtronic™ Mark II controls but were later upgraded to Mark V. 1983-1985 – David Lucier is assigned by GE to work at TEPCO in Futsu, Japan. He heads a group of 15 field engineers on this assignment. He is succeeded by Muggs Norris and finally Dave Smith, who was initially headed up the start-up team. 1986 – David Lucier voluntarily resigns from GE. He starts his first company: I&SE Associates of Schenectady, Inc. I&SE provides field engineering services on GE gas turbines including training, troubleshooting and consulting. Company is disbanded in 1998. 1991 – GE introduces the MS7001EA gas turbine (evolved from the 7B from 1970) which is rated at 90 MW for ISO conditions. Firing temperature is 2200˚F. Speedtronic™ Mark V is introduced. Dry Low Nox (DLN) systems are first employed. 1999, June – David Lucier and Charles Pond start a new company: Pond and Lucier, LLC. Company provides field engineering services for owners and operators of General Electric gas and steam turbines. 2000 – GE introduces the MS7001FA gas turbine which is rated at 150 MW for ISO conditions. The so-called “F” technology can fire at a temperature of 2400˚F. Turbine utilizes Speedtronic™ Mark VI controls. 2004 – GE introduces the MS9001H gas turbine (50-cycle) which is rated over 200 MW for ISO conditions. The so-called “H” technology has steam-cooled turbine buckets and can fire at a temperature of 2600˚F with Mark VI controls. 2010, January – Dave Lucier buys out Pond and becomes sole owner of Pond and Lucier, LLC. Name is changed to PAL Turbine Services, LLC. Thus, we have the Time Line of Gas Turbine Technology. Tags: gas turbines, turbines
Peaking Power, Chapter 3: Gas Turbine Performance, Simplified It is generally known by observation that gases have particular characteristics. Variables like pressure (P), temperature (T) and volume (V) have a special relationship in gases that is best understood when considering the model below. In words, Pressure (P) multiplied by Volume (V) and then divided by Temperature (T) is always constant. It is a different constant for each gas. Air, which includes many gases, would have still a different constant than the particular gases in the mixture. Finally, when fuel (natural gas, for instance) is mixed with air in a gas turbine combustion system, still another constant is realized. However, when considering the various stages of the Brayton Cycle, the specific constant does not matter in the analysis. In equation form, that would be: (P) multiplied by (V) then divided by (T) = constant or simply (P x V) ÷ T = constant This relationship holds through all stages of the gas turbine. It is important, however, that the units of each of the three variables be correct. In English units, that would be:
Pressure (P) in pounds per square inch absolute, (psia) Temperature (T) must be in degrees Rankin, (˚R). That is, to convert from Fahrenheit to Rankin, it would be: T (˚R) = T (˚F) + 460 Volume (V) must be in cubic inches, (in³)
Or it can be said, simply: P (psia) x V (cubic inches) ÷ T (degrees R) = constant For the four regions of the gas turbine on the pressure-volume (PV) diagram we have: Region 1 – 2 Compresion
Region 2 – 3 Combustion
Region 3 – 4 Expansion
Region 4 – 1 Exhaust
Thus, we have: P1 x V1 = T1
P2 x V2 = P3 x V3 = T2 T3
P4 x V4 T4
Imagine a cubic foot of air. Assume that the “box” of air has dimensions of 12 x 12 x 12 inches, as it enters the compressor. Try to envision this air cube passing through the gas turbine.
From the compressor inlet (point 1) the air cube passes through the axial-flow compressor diminishing in size through each stage. The air cube, now smaller in size, leaves the compressor discharge (point 2) and enters the combustors at essentially the same pressure. That is, P2 = P3. 21
Then the smaller air cube expands through the combustors to the first stage turbine nozzle, to a point just in front of the turbine buckets at essentially constant pressure (point 3). After expanding through the turbine stages, the air cube increases in size, continuing out the exhaust reaching approximately the same pressure as the compressor inlet (point 4), That is, P4 = P1.
Fig 3-1 - Brayton Cycle-Pressure Volume Diagaram
We know that pressure, volume and temperature are variables. However, they only vary throughout the gas turbine cycle in the relationship described above. Also, notice that the pressure from points P2 to P3 is considered constant, horizontal line on the P-V diagram. Thus, in the combustion zone, they would then P2 and P3 cancel out on each side of in the following equation leaving: V2 = V3 T2 T3
The formula only works for temperatures in degrees Rankin. Converting to Fahrenheit we have ___V2___ = (T2 + 460)
___V3___ (T3 +460)
Take a typical General Electric model series MS5001P, a very popular gas turbine in the worldwide market. Assume that the turbine firing temperature is Tf = 1800 degrees Fahrenheit. Assume that the air temperature at the discharge of the compressor is approximately 500 F. Thus, we would have: ___V2___ = (500 + 460)
___V2___ = (960)
___V3___ (1800 + 460)
Thus, in the gas turbine‟s combustion system, the pressure remains essentially constant (P2 ≈ P3). However, the volume more than doubles, or in this case V3 = 2.35 (V2)
Fig 3-2 - Compressor End View of a Typical Gas Turbine View of the gas turbine in Fig. 3-2 above showing the compressor and turbine rotor installed inside the casings. Notice how the compressor stage passageways diminish in size as the air flows through the turbine (getting smaller with every stage). In Fig. 3-3 below, the compressor rotor blades diminish in size from the R-0 stage to the R-16 stage; again, the air passage ways for the air to flow diminish through this 17-stage compressor.
Fig 3-3 - Compressor Rotor View Gas turbine performance can be affected by many variables. One of the most important factors is the change of ambient temperature at the compressor inlet. Figure 3-4 below shows how changes in ambient temperature impact such variables as Heat Rate, Exhaust Temperature, Exhaust Flow, Fuel Flow and Power Output. Notice how the Heat Rate (thus the Thermal Efficiency) improves on colder days. Fuel Flow does increase, as does Power Output. However, notice that the slope of the Power line is steeper than that of the Fuel Flow, which flattens the Heat Rate line. More power output for less fuel means higher efficiency.
Fig 3-4 - The Effects of Changes in Compressor Inlet Temperature
So what can I do to improve gas turbine performance without spending tons of money?
Check compressor discharge pressure (CPD). If it is low, you should clean the compressor by on-line washing or other techniques.
Borescope the turbine on a regular basis. If the trailing edge of the first-stage turbine nozzle is distorted or missing metal, performance will suffer. The forces acting on the buckets that develop power output is diminished by a reduction in back pressure on the compressor reduces CPD.
Be sure that the inlet guide vane (IGV) angles are set properly. This can be determined during a borescope inspection. Incorrect settings can reduce air flow and adversely affect power output.
Record FSNL Data. Once the gas turbine reaches operating speed (called Full Speed, No Load or FSNL), record the following data: 26
1. Compressor Discharge Pressure (CPD) 2. Fuel Flow (gpm, if liquid fuel or SCFM, if gas fuel) 3. Average Turbine Exhaust Temperature (TTXM) 4. Megawatts (MW) – Zero at the moment. Then begin loading the generator and record power output (MW) and observe the other data points (CPD, FF and TTXM) until base load is reached. These variables should increase in essentially equal proportions from the FSNL data. Once base load is reached, you should determine if the correct turbine firing temperature, Tf is reached. Contact PAL Turbine Services, LLC and David Lucier for assistance in these calculations. Tags: borescope, gas turbines, turbines
Peaking Power, Chapter 4: Sir Frank Whittle, Father of the Gas Turbine Discussions about gas turbines and their application to land-based power generation, gas pipeline and process plants should rightfully begin with British engineer Sir Frank Whittle. The key word here is application. His predecessors were many, as the time line in Chapter 2 outlines, but Whittle should be credited for bringing ideas regarding the jet engine to fruition in industrial applications. In 1941, Sir Frank Whittle designed the first successful turbojet engine for air defense during World War II. Dubbed the Gloster Meteor, it flew in defense over Great Britain. Whittle improved his jet engine as the war progressed. He shipped a prototype engine to General Electric in the United States in 1942. GE built America‟s first jet engine for military aviation applications the following year. Whittle came to the USA for the first time on a secret mission in the summer of 1942. He met with officials from General Electric in Lynn, MA and Bell Aircraft Company in Buffalo, NY. Later in 1942, he visited GE in Schenectady, NY, where a rudimentary propeller jet engine was under development. Whittle‟s comments and suggestions to American engineers proved invaluable in modifications and improvements that soon followed. One can argue that the development of jet engine might have been accelerated had World War II lasted longer. However, the other side of that argument is that the application of turbotechnology to other industries became a post-war quest of American industry. In the eyes of many engineers on both sides of “the pond,” this method of power production and propulsion could be used to drive land-based generators, compressors and other load devices, as well as to propel ships and aircraft in commercial applications. All that was needed was funding and the imagination of the engineers involved, eager as they were to apply this innovative prime mover.
Fig. 4-1: Sir Frank Whittle and his multi-combustor jet turbine (circa 1941) The multi-combustor, turbo-jet engine (hereafter called the gas turbine) has Frank Whittle proudly standing beside it in Fig. 4-1. Notice that there are 10 combustion chambers (tube shaped) encircling the engine, with stainless steel nozzles to inject fuel into them at the front ends. The chambers are interconnected by cross-fire tubes, as is common on most modern gas turbines. The exhaust diffuser is in the center. The reverse-flow concept of the hot gases is obvious from the photograph. So are the transition pieces curling from the discharge of each combustor. “If necessity is the mother of invention,” as preached to engineering students by college professors, then the end of WW-II brought many needs to the front burner ready to be invented. Jet engine technology needed to be harnessed and applied to other commercial endeavors. As a prime mover, the gas turbine needed to find applications that could deliver power to other modes of transportation, electrical power delivery and natural gas pipelines prime movers. However, as inventors soon found, not every idea has a viable application to industry, or a willingness of the public to accept them. Engineers like Whittle would encounter doubters, the enemies of progressive thinkers. Progress often depended upon inventors who could convince entrepreneurs and angel investors to take a chance on their ideas and innovations. This presumes that negative forces are not overwhelmingly against such visionaries. As explained in later chapters of this blog, GE engineers struggled to get funding in a fledgling gas turbine department in Schenectady, NY in the 1950s. It is uncertain if Frank Whittle could have envisioned a modern gas turbine like the one shown in Fig. 4-2 below. A single-fuel (natural gas) General Electric MS7001EA gas turbine (approximately 80 megawatt rating) is shown, with fuel line “pigtails” coming from the manifold
on the left leading to each combustor. The chambers themselves are inside the combustion wrapper, which encircles the turbine, so only the covers are showing.
Fig 4-2; Multi-combustor GE MS7001EA Gas Turbine inside Combustion Wrapper (circa 2000)
Since the combustors are interconnected via cross-fire tubes, only one combustor needs to have a sparkplug (igniter) and another, a flame detector. However, for redundancy and reliability, modern gas turbines typically have at least two of each, as shown in Fig. 4-3.
Fig 4-3: Typical configuration of Multi-combustor Gas Turbine with Spark Plugs & Flame Detectors Design of combustion systems, like those depicted herein, seems to be a “settled” issue. Most manufacturers have decided that this is the design that makes the most sense. It allows for temperature equalization and flow distribution to the first-stage turbine nozzle and rotating wheels with buckets (blades) that develop the output power. Refer to Fig. 4-4 below.
Fig 4-4: Cross-fire tubes between adjacent combustion chambers
Fig. 4-5 below should be studied for its completeness regarding the design of a typical modern combustion system for a GE MS7001EA gas turbine. Notice that the combustors are “canted” in design to straighten the hot gas flow through the transition pieces toward the first-stage nozzle (not shown). Also, this design shortens the length of the turbine and thus bearing spans. The reverse flow of the air from the compressor discharge casing is also shown entering the combustor.
Fig 4-5: Typical Modern Combustion Chamber and Transition Piece Configuration Other areas of development have also occurred over the past 70 years with gas turbine technology. Advances in metallurgy, ceramic coatings and internal cooling designs have evolved over the past seven decades, to a point where efficiencies and higher internal firing temperatures have made the gas turbine a viable competitor to other forms of power generation. In conclusion, over sixty years ago an engineer from Britain named Frank Whittle envisioned, designed and built a multi-combustor, aero-derivative gas turbine engine for land-based applications. His innovative design in gas turbine technology has prevailed for the following six decades well into the 21st century. Tags: control systems, Frank Whittle, gas turbines, turbines
Peaking Power, Chapter 5: Gas Turbine Planes, Trains & Automobiles After World War II, it became popular to apply a new technology to modes of transportation including planes, trains and automobiles. The combustion (gas) turbine, under development during the war, found many commercial applications. Some succeeded; some didn‟t. Some came up against forces that crushed such innovative ideas. Planes, trains and automobiles became the focus of these applications by 1950.
Planes From the late 1950s to today, jet-powered commercial airplanes have been a permanent presence in the skies overhead. However, entering this post-war decade, airplane manufacturers and airline companies were not anxious to go with jet-powered aviation. Jets were playing a military roll, but should they propel commercial aircraft? They consumed enormous volumes of fuel. Airport runways for civilian aircraft were too short. The capital investment required was projected to be enormous. An authoritative report by a prestigious consulting firm declared that jets could not carry the loads for long-range flight. If anything, they were perceived as a luxury for the affluent traveler. Two crashes in less than 20 months of Britain‟s Comet appeared to confirm that the world was not ready for jet-powered commercial aircraft. Turboprop aircraft was presumed to be the logical replacement for aging propeller transports.
Fig. 5-1: Jet-powered Pan Am 707 Arrived in the early 1950s Enter the Chairman of Pan American airways, Juan Trippe, with other notions and visions. He stood alone in his perception of where commercial aviation was headed. Trippe could foresee a demand for faster transportation that carried many more passengers all over the world. Pan Am‟s main supplier of passenger aircraft at the time was a company named Douglas. They had a long-range military aircraft on the “drawing boards” that were to use Pratt and Whitney jet
engines, but they were not large enough or powerful enough to meet Pan Am‟s needs for a profitable venture. Trippe was not satisfied. He began courting Rolls Royce in Britain for jet engines. In his mind, there was nothing like international competition to bring Pratt &Whitney to their senses. Rolls Royce offered to sell Trippe one hundred twenty of its bigger jet engines. Armed with a commitment on engines, Trippe threatened to look abroad for engines if Douglas refused his request. Douglas reconsidered and agreed to build twenty-five DC-8 passenger airplanes. Not one to put all his “jets in one basket,” Trippe contracted with Boeing for 20 of its newly conceived 707 aircraft. This bombshell announcement that Trippe of Pan Am had just ordered 45 jets for numbing sum of $269 Million, announced in October 1955 to a gathering of world airline leaders, shocked the aviation industry and especially Boeing. Learning that Douglas was building a larger jet, Boeing concluded it would have to build a competitive airplane and hastened to renegotiate its contract on Pan Am‟s terms. Furthermore, other airlines realized that to compete with Pan Am they too would have to invest in jet fleets too. Commercial aviation, with its a new gas turbine (jet) engines, was born. With General Electric, Rolls-Royce and Pratt & Whitney providing the power, this mode of air transportation has become an integral part of air transportation of people and cargo. However, Pan American Airlines did not survive beyond the late 1980s to see this phenomenon for other competitive reasons, but that‟s another story.
Trains General Electric produced several models of gas turbine generators for locomotives applications in the late 1940s and 1950s. The only successful production models were sold to the Union Pacific Railroad for cargo hauling in the remote western United States. Records show that 55 turbine/generators were sold for this application. They came in two types:
The first version was a 4,500 HP model introduced in 1949 for UP. It was called a UP50 and installed on locomotives manufactured in Schenectady, NY by American Locomotive Company (ALCO). The prime mover was a General Electric gas turbine driving a generator to provide electric power to eight traction motors. It was a dual fuel unit: starting fuel was a lighter (diesel) oil and then transferring to “Bunker C” during operation. Fuel flow was controlled by a Young & Franklin fuel regulator, described in Chapter 7 herein.
Note: In those days, Schenectady, NY was known as the “City that Powers and Moves the World.” This slogan was a tribute to the contributions and world-wide recognition of GE and ALCO in many commercial industries.
The second train model went into production in 1958. It consisted of two car bodies, a lead control unit and a second unit containing a 10,500 HP turbine. Each car body had two C trucks. At first, the two generators attached to the turbine were rated together at 8,500 HP but were later uprated to 10,000 HP. 34
Fig. 5-2: Gas Turbine Powered Locomotive for Union Pacific UP50 (circa 1950) Thirty large turbines were produced by GE and ALCO. Compared to first g,eneration of locomotives, these machines were very reliable. They burned Bunker C a thick, black oil which was considered waste fuel at the time, was initially very inexpensive. Heated tenders cars (used to keep the fuel from solidifying) were provided for each locomotive, custom made from old steam tenders. See Fig. 5-3. Bunker C became more expensive when it became an ingredient for making plastics. Increased fuel expense doomed the gas turbine, which could not operate with the fuel efficiency of the diesel engine. A way was not yet found to cool the turbine blades like a piston engine cooling system, so the turbine had to operate at a lower, less-efficient “firing” temperatures than a diesel. Had the manufacturers invested in research and development in gas turbine cooling, as was done later in the century, the attitude toward gas turbines as prime movers in the transportation industry may have been much different.
Fig. 5-3: Turbine Tender carrying “Bunker C” Fuel Gas turbines remained in service roughly from 1950 to 1969. None of the first generation turbines remains in operation. At least one of the second generation turbines is currently on display in Ogden, Utah. 35
Fig. 5-4: Gas Turbine powered Locomotive The 4,500 horsepower Gas Turbine Electric Locomotive (GTEL) streaked across Union Pacific rails as part of a fleet that once seemed the successor to both steam and diesel motive power. In 1954, the Union Pacific took delivery of its second order of fifteen GTEL. These new locomotives included significant improvements over their predecessors, notably roof-mounted air intakes and recessed side walkways that gave trainmen greater access to vital turbine‟s components. Because of the latter distinctively featured walkways, the new units became commonly known as Verandas. For the next decade, this style of locomotive represented the cutting edge of the Union Pacific‟s quest for horsepower for hauling more tonnage. As a large railroad system, vast uninhabited expanses in the western states, Union Pacific constantly searched for the best means to move maximum tonnage at the highest possible speed. The UP Motive Power Department took the search a step further by squeezing maximum horsepower out of the least number of locomotives. These operating concerns led to some of the most powerful and largest locomotives ever, from the 4-8-8-4 Big Boy steamer to the DD40AX Centennial diesel. In 1948, the ultimate power solution was seen in demonstrator #100, a product of the American Locomotive Company (ALCO) and General Electric (GE). It would eventually become Union Pacific #50, the first of the only fleet of GTEL ever run on rails in the USA. The GTEL drives a generator that, as on a diesel-electric locomotive, provides electric power to the traction motors. Initially, advantages over both steam and diesel locomotives were found in this novel power plant. With fewer parts to maintain than a diesel and cheaper Bunker C fuel oil, the turbine decreased operating costs. The GTELs generated 4,500 horsepower and the Veranda produced 137,930 pounds of starting tractive force. They pulled the same tonnage several miles per hour faster than a diesel of equal horsepower. Verandas ran double-headed with GP-9 diesels and 4-8-8-4 Big Boys to pull seemingly endless strings of heavy freight cars. Their noisy gas turbines (compressor inlet high audible whine) restricted these units from operating in highly
populated communities. Instead, they ran on the wide open spaces of the Union Pacific system, such as along the Wyoming Division railways. For more about this subject, go to http://www.uprr.com/aboutup/history/loco
Automobiles Following its pioneering work with jet engines during World War II, an English firm named Rover developed a gas turbine engine primarily for automobile use. The first gas turbine roadster, the Rover Jet 1, was introduced in 1951. See Fig. 5-5 below. A dozen years later, the Rover BRM ran in the 1963 Le Mans race powered by a gas turbine engine.
Fig 5-5: Gas Turbine Powered “Jet 1” by Rover (circa 1951) The Jet-1 achieved a top speed of 152 miles per hour on a race track in England in 1951. According to the back of this photograph on a postcard, it could accelerate from 0 to 100 mph in 13 seconds. That‟s respectable performance for a “first-of-a-kind” roadster. Other cars of the era, the MGTD midget and the Triumph TR2, certainly would have had difficulty competing with this sleek beauty. A schematic drawing of the engine is shown in Fig. 5-6 below.
Fig. 5-6: Cutaway view of automotive gas turbine engine used in the Rover Jet-1 The first competitive attempt to race a gas turbine car at Le Mans, the famous 24-hour endurance race in France, came in 1963 with the Rover BRM. It ran successfully but was too inefficient, having too high fuel consumption for this kind of racing. Two years later a regenerator was added to recover some of the lost heat from the exhaust and reduce fuel consumption. Regeneration to pre-heat the compressed air entering the combustor, made the later version very competitive as it finished 10th in the enduro race. The 1965 Le Mans car (see Fig. 5-7 and 5-8 below) overwhelmingly proved the turbine car‟s reliability and endurance capability.
Fig 5-7: Rover BRM Gas Turbine Car at the Le Mans race of 1965 Car #31 did not win the race but it certainly left lasting impressions. Renowned driver English driver Graham Hill and diminutive American driver Richie Gunther shared the wheel in the 24hour challenge. Fig. 5-8 shows the car during a driver change and a pit stop at Le Mans.
Fig 5-8: Pit Action for Rover BRM Gas Turbine Car at the Le Mans The Indianapolis 500 race in 1967 had an unusual entry designed by the famous driver, Andy Granatelli. This gas turbine powered open-wheel racer was driven by the famous Parnelli Jones and had a sixth place qualifying speed of over 166 mph. Mario Andretti drove a piston engine at two miles per hour faster and won the pole position. Granatelli‟s side-mounted gas turbine engine racer led the race for remarkable 171 of 200 laps. A gear box failure, reportedly a $6 part, in the 197 lap (just 7 ½ miles from the finish) caused the STP Special from Studebaker to slip back to 6th position. It ran on Firestone tires and set 18 track records during its first attempt. Its fastest lap during the race was remarkable 164.926 miles per hour.
Fig 5-9: 1967 STP Special Studebaker driven by Parnelli Jones (now held at the Indy Racing Museum) According to a recent article in Pit Talk magazine by Jan Lamkins, the 4-wheel drive turbopowered Indy car dubbed “Silent Sam” whizzed around the track with Jones at the steering wheel. The car performed magnificently, only to lose to A.J. Foyt, who won the race for the third time. Pit Talk noted: “For 1968, USAC instituted rules that reduced the size of the turbine engine allowed. Nonetheless, Granatelli teamed with Colin Chapman and Lotus to build a wedgeshaped, 4-wheel drive Lotus 56. The STP team showed up with 3 cars, which would be driven by Joe Leonard, Art Pollard and Graham Hill. Also of note, Carroll Shelby showed up with two turbine cars that looked similar to the 1967 side-engined car. These were to be driven by Denis Hulme and Bruce McLaren. The cars practiced but were withdrawn for „safety‟ reasons.” Imagine this, with racing legends noted above, had one of the turbine cars actually won the Indy 500, would we be driving turbine cars on the streets today? How different might the automobile industry be today if a turbine option be offered by Detroit? Could demand from the public be denied? We can only imagine. There is an old adage in car racing worth noting: What wins on Sunday, sells on Monday.
Fig 5-10: In the pits at the 1967 Indianapolis 500 race (Courtesy of Indy Museum) Of course, there is another unspoken axiom: if you can‟t beat them, keep changing the rules until then can‟t compete with you! More size restrictions were put on turbine car engines in the next two years. Only one turbine-powered car showed up in Indianapolis in 1969 to race. Jack Adams Special conformed to the newest restrictions in his new-look car and nearly qualified but was bumped on the final day. The qualifying agency, USAC, finally banned turbine cars (and 4wheel drive racers) a year later. So, in the final analysis, the innovative turbine race cars, some twenty years in development, came to race at Le Mans and Indy, only to find that racing officials did not welcome them into the fold. Could the tactics of those who write the rule books, or perhaps their love for the sound of pistons engines on race tracks, have sounded the final death knell for these new turbine racers? The gas turbine engine can be compared with a 4-cycle piston engine as shown in Fig. 5-11. The piston engine shown below is an induction stroke followed by a compression stage. Fuel is then injected, mixed with air and combusted. Expansion takes place as the piston again moves downward. The exhaust stroke follows as the hot gases are sent to the atmosphere. In the case of the gas turbine engine, air is sucked into the compressor. Once the compression takes place, the air is mixed with fuel and combusted. The hot gases then expand through the turbine section where power is developed and the gases continue to the exhaust. On some engines, a regenerator (heat exchanger) is utilized capture some of the heat and transfer it to the compressed air entering the combustor and thus reduce fuel consumption and improve cycle efficiency.
Fig 5-11: Gas turbine cycle compared to conventional 4-cycle Automotive Engine A few touring sedans were tried in the decade of the 1960s, but efficiency (gas mileage) soon became an issue with these non-regenerative cycle designs.
Fig. 5-12: In foreground, gas turbine powered 1956 Rover T3 Sedan in England Meanwhile, over the Atlantic Ocean in the USA, Plymouth was building a passenger car that utilized the gas turbine engine for day-to-day use by motorists. Fig. 5-13 shows a mechanic 42
working on one model. Keeping this in perspective, 1959 was the era of Sputnik and just before President John Kennedy was elected president. What if President Kennedy had challenged America, instead of sending a man to the moon in this decade, but to put a turbine-powered vehicle in every garage? How different motoring on American interstate highways have been decades later!
Fig. 5-13: Mechanic works on an American-made 1959 Plymouth sedan which had a gas turbine engine Planes, trains and automobiles all require prime movers to propel them along. Plane manufacturers took the technology of gas turbine engines and made them the cornerstone of their prime mover fleets. Trains and automobiles, however, never embraced this innovative new engine after the 1960s. Too bad! The advances in gas turbines over the past 50 years have made this technology much more viable power source for trains and vehicles. Our lives would be better for it. Tags: aircraft, automobiles, control systems, Gas turbine generators, gas turbines, locomotives, Rover, turbines
Peaking Power, Chapter 6: Rutland on the Leading Edge Rutland, Vermont is probably not a place one would expect to be in the forefront in new technology in power generation, unless perhaps it was in mountain stream hydropower. Even less likely is this town‟s involvement with one of the first land-based gas turbines to drive an electric generator. But that is just what happened sixty years ago. In 1951, three new gas turbine plants manufactured by General Electric (GE) in Schenectady, NY were installed on the west end of Rutland, elevating this New England city to the leading edge of power technology. The owner and operator of these plants was Central Vermont Public Service (CVPS). GE called this design combustion turbine a frame size 3. There were only ten turbines of this design ever manufactured by GE. According to their published records, all were installed in the early 1950s in such diverse locations as Maine, Texas, Connecticut and the aforementioned Vermont. Note: The very first GE installation in power generation was at Belle Island Station of Oklahoma Gas and Electric Company was two years earlier. It was a Frame 3 but a simple-cycle, singleshaft generator drive, with the model designation 3001. Fig. 6-1 below shows a colored cross-sectional view of the Rutland gas turbine. As depicted in the rendering, there are compressors at each end. The low-pressure (LP) axial-flow compressor is on the right; another axial-flow compressor (so called high-pressure, HP) is on the left. Air from the LP compressor is intercooled before going to the HP compressor. Air discharging from the HP compressor is then pre-heated by regenerators before going the combustors. There will be more on this later in the chapter.
Fig. 6-1: Cutaway of the 5000 KW “Kilowatt Machine at Rutland, VT According to the CVPS unit operator log books, the first of three plants went into commercial operation on October 1, 1951. The three units were installed side by side in a building that is now an electrical repair shop for transformers, since the last gas turbine plant was retired in 1987. Unit #1 is shown in Fig. 6-2 below.
Fig. 6-2: Elevated view of plant operators recording data on Unit #1 at Rutland, VT (circa 1951) The Rutland plants were very advanced for their time. In fact, they would be considered extraordinary even by today‟s standards. Unlike the simple-cycle, peaking gas turbine power plants that became popular in the late 1960s, in reaction to the great Northeast Blackout of 1965, these first gas turbine power plants were very complex. Dubbed the “Kilowatt Machines” by GE engineers, the indoor in power stations in Rutland were both inter-cooled and regenerative cycle. See Fig. 6-3 below. Each plant could develop approximately 5,000 kilowatts when operating at an ambient inlet temperature of 80 degrees Fahrenheit at the Rutland elevation. Crisp and clean mountain air was sucked into the inlet of the LP compressor. The LP compressor was driven by the LP turbine stage. Air from the discharge of LP compressor was not only higher in pressure but at an elevated temperature, which hurt overall performance. GE used twin intercoolers (in parallel) to reduce the temperature at the LP compressor discharge (while maintaining the pressure) before piping it into the high-pressure (HP) compressor for further compression.
Fig. 6-3: Cycle Diagram of the CVPS plants The HP turbine provided the power to both the HP compressor, and through a speed reduction gear box, the AC generator. The air from the HP compressor discharged into twin regenerators. Installed in parallel to divide the airflow, the regenerators transferred heat from the turbine exhaust to the air from HP compressor discharge. This compressed and pre-heated air was then directed into the six combustors where fuel was burned adding additional heat.
Fig. 6-4: The late Norton Mark Cobb, CVPS Superintendent of Gas Turbines, kneels to take readings next to a “Kilowatt Machine” (circa 1951) CVPS would start a plant on #2 diesel oil and later transfer to the heavier Bunker “C” fuel. The ultra-hot combustion gas, firing at 1500 degrees Fahrenheit when at base load, was then expanded through the two sections of the turbine. Approximately two-thirds of the power 46
developed was needed to drive the two compressors. The remaining one-third was used to develop electrical power. Finally, after transferring most of the heat to the air from the HP compressor through the regenerators, the gas was discharged the exhaust back into atmosphere. Even by today‟s standards, the gas turbine power plants installed by CVPS at the end of Greens Hill Lane in Rutland six decades ago would be considered advanced and sophisticated. The plants are now retired. According to the logbooks, the last of the three plants to be retired (Unit #1) ran its final time in 1987. I saw it run around that time. It had over 100,000 operating hours when mothballed and later sold for scrap. Note: GE was offered the units at museum prices but declined. A shame.
Fig. 6-5: Block Diagram showing arrangement of gas turbine-generator components
Specifications Item Description 1 9-stage, axial-flow LP compressor, 7200 rpm (driven by LP turbine) 1 11-stage, axial-flow HP compressor, 8694 rpm, (driven by HP turbine), variable inlet guide vanes (VIGV) 6 Combustors (liquid fuel) 1 2-stage LP turbine (7200 rpm when at 100% rated speed) 1 1-stage HP turbine (8694 rpm when at 100% rated speed) 1 Reduction gear (8694 rpm to 3600 rpm) driven by HP turbine 1 5000 KW generator, 6250 KVA, .8 power factor, 3-phase, 60 cycle, 3600 rpm driven by HP turbine 2 Regenerators (connected in parallel) 2 Intercoolers (connected in parallel) 2 Starting motors for both for LP and HP compressor
Fig. 6-6: The late Ira “Chick” Evens of CVPS measures compressor blades during an inspection in 1951.
Fig. 6-7: Basic Control and Protection System for the “Kilowatt Machines” General Electric sold many regenerative cycle plants over the years, mostly to gas pipelines and process plants where the load device was a compressor rather than a generator. The main advantage of regeneration was to reduce fuel consumption (resulting in a lower heat rate) for plants that operated continuously for thousands of hours per year, as was often true in the industrial market. In the power generation field, however, this cycle lost its popularity, primarily due to the high repair costs associated with the regenerators. Regenerators that are started and stopped frequently can experience tube cracking that can be costly to keep in good operating condition. Inter-cooled gas turbines, on the other hand, became even less popular probably because GE was able to manufacture more efficient axial-flow compressors with more stages. Typical GE compressors today have 17 or 18 stages with discharge pressures exceeding 175 pounds per square inch (psig). Long before waxed hickory boards with bear trap bindings helped put Rutland, Vermont on the map for skiing at nearby Killington, this city was truly a proving ground for a new means of electrical power production. The three old “Kilowatt Machines” are gone now from the building at the end of Green Hills Lane, but their contribution to the application and development of gas turbine technology should never be forgotten. Tags: Blackout, Central Vermont Public Service, Combustion, Compression, CVPS, Gas turbine generators, gas turbines, Great Northeast Blackout, inter-cooled, Kilowatt Machine, regenerative cycle, Rutland, Schenectady
Peaking Power, Chapter 7: The Fuel Regulator The first control system used on GE gas turbines in the late 1940s was manufactured by Young & Franklin (Y&F) of Liverpool, NY. It was called the Fuel Regulator, although fuel does not actually flow through the device. It is a mechanical-hydraulic control (MHC) device that has an electric governor and pneumatic temperature control element. It was quite sophisticated for its day, with nearly 1000 turbines shipped with this control in the 1950s and 1960s. Hundreds of gas turbines are still in operation today employing the device, some with over 300,000 operating hours. The fuel regulator in Fig. 7-1 is installed on a gas turbine in Williston, ND owned by Montana Dakota Utilities (MDU) circa 1953.
Fig. 7-1: Fuel Regulator Serial on gas turbine owned by MDU in Williston, ND The Y&F fuel regulator is a very sophisticated control device. It has a “minimum value gate” that protects the gas turbine from adverse operation. The MVG compares fuel limits, turbine speed and exhaust temperature on a continuous basis. The sub-system that “calls for” the least amount of fuel, as determined by variable control oil (VCO) output pressure, will be “in charge.” This is the internal decision maker that ultimately sends a signal VCO pressure to the fuel pump or gas control valve, as applicable, to regulate flow. Thus, the fuel regulator has a comparator and method of “calculating” the correct amount of fuel required by the gas turbine. The MVG is thus a computer with some variable inputs and one limit upper limit at any given time. See the chart below for typical values. In these early gas turbines, fuel flow was not measured directly by the control system; on the contrary, fuel flow was simply “limited” indirectly by measuring speed, exhaust temperature and rate of change of temperature. 1. Zero Fuel prevents flow until specific firing conditions are met, namely: minimum speed and system purge. Sparking is also restricted to the appropriate time for a specific period time (usually one minute). 50
1. Fuel Limits are pre-adjusted settings (approximate ranges for adjustment shown). Regulator Setting Range (psig)
Zero Effective VCO Less than 40 psig Zero pump stroke Maximum VCO
170 – 200 psig
Maximum Fuel (load)
80 – 100 psig
Firing fuel limit
100 – 130 psig
Accelerating fuel limit
50 – 75 psig
Minimum (shutdown) fuel
1. Speed Control is set by the governor in an operating range of 95 to 107 percent of rated speed. 1. Minimum Fuel is a setting that permits shutdown of the gas turbine under flame. 1. Average Turbine Exhaust Temperature is monitored, as a way of controlling the turbine firing (inlet) temperature.
FUEL REGULATOR APPLICATIONS 3500 KW & LOCOMOTIVE TYPE OF 5000 HP UNIT LOCOMOTIVE REGENERATIVE 5000 HP 5000 KW (RAILROAD) (RAILROAD) CYCLE SIMPLE GENERATOR CYCLE Regulator Group
VCO Servo Bias
HP Altitude Bias Compressor Discharge Pressure Altitude HP Compressor Inlet Pressure None
Control Rheostat VCO Pressure Range (PSIG)
Chart 7-1: Several fuel regulator designs for various applications (data circa 1950)
The person responsible for assembling these fuel regulators over the past 40 years has been a man known as Mr. Fuel Regulator, the late Bill Brooks of Y&F. Over the first two decades when the fuel regulator was offered as a control system ending in 1969, many improvements were made without changing the basic functions of the device. Fig.4 shows a fuel regulator that was reconditioned to be reinstalled on a gas turbine still located in Pennsylvania (installation circa 1967). There are some obvious physical changes to the one in Fig. 1; however there are no functional differences.
7-2: Mr. Fuel Regulator (the late Bill Brooks) receives gift from Dave Lucier (right)
Fig. 7-3: Fuel Regulator installed on accessory gear on right (circa 1968) Over the past six decades, electrical systems have changed and evolved. Many of the support devices to the fuel regulator have become obsolete, extinct or impossible to obtain. The manufacturers no longer offer replacement units. No longer can you get spare parts or modules. These include: GE/MAC temperature control, Fisher electro-pneumatic transducer and the Fairchild flame detector. Yet, the fuel regulator itself can be replaced or reconditioned. These, along with their ancillary components (Y&F hydraulic positioning servos, Y&F gas control valves, Y&F VCO dividers and OilGear fuel pumps) can be recycled by the manufacturers of companies like PAL Turbine Services, LLC. Fig. 7-4 shows some gentlemen who were very active in the Product Service Department of the Gas Turbine Division of General Electric during the Fuel Regulator era. Left to right include Larry Mitter and the late George Kennedy and Geoff Jarvis. Mr. Mitter went to work for Y&F in the 1970s and became a vice president in engineering with the firm. George Kennedy was very involved in the GT Start-up Program, training numerous field engineers on fuel regulator control and protection systems. Mr. Jarvis was a mechanical “guru” who was very supportive to clients owners and GE field engineers during his product service days. Kennedy and Jarvis both died in the late 1990s.
Fig.7-4: Larry Mitter, George Kennedy and Geoff Jarvis (left to right) 53
The GE/MAC system had two slide-out modules (See Fig. 5 below) that allowed testing and calibration. The millivolt-to-current (MV/I) amplifier is on the left and the programmer is on the right. The output signal (10 to 50 milliamperes) was sent to an electro-pneumatic transducer (not shown) that, in turn, sent a proportional air signal (3 to 27 psig) to the fuel regulator. If the fuel regulator MVG determined that the exhaust temperature was “too high,” it would limit or reduce the output VCO pressure and internal reduce fuel flow.
Fig. 7-5: Original GE/MAC Exhaust Temperature Control (circa 1968) Flame detection was done by a Fairchild Thermocouple Flame Relay like the one shown in Fig. 7-6. Like the GE/MAC, it took a millivolt signal from an averaging cabinet that represented the turbine exhaust temperature.
Fig. 7-6: Fairchild Thermocouple Flame Detector (circa 1968) 54
Modern programmable logic controllers (PLC) have been employed to replace these devices while retaining the fuel regulator and all its intended functions. A few external improvements and features have been made but the fuel regulator is still “in charge” of fuel flow to the gas turbine combustors. Sequencing lights on the right give the operator indications as event occur in the normal starting, loading, unloading and shutdown of the gas turbine.
Fig. 7-7: PLC used in conjunction with original Fuel Regulator The PLC below can continuously monitor such variables as:
Time of operation, hours/minutes Turbine Speed, Ts, revolutions per minute (rpm) Fuel Flow, FF, gallons per minute (gpm) Average Exhaust Temperature, Txa, in degrees Fahrenheit (˚F) Fuel Pressure, FP, in pounds per square inch-gage (psig) Fuel Demand Signal: Vco in pounds per square inch-gage (psig) Bypass valve position, LVDT, in percent (% stroke)
Fig. 7-8: PLC Display showing: speed, fuel flow, exhaust temperature, fuel pressure and VCO
Summary: The fuel regulator is alive and well in many gas turbine power plants. It is an ingenious device that has proven its worth and reliability in gas turbine operations for over 60 years. Few computer systems have lasted as long or performed as well as the Young & Franklin fuel regulator. Tags: Bill Brooks, flame detection, fuel regulator, Gas turbine generators, gas turbines, PLC, programmable logic controller, Young & Franklin
Peaking Power, Chapter 8: Compressor Drives for the Industrial and Gas Pipeline Industry In the 1950s, General Electric designed, constructed and installed hundreds of 2-shaft gas turbines. The units had two, mechanically-independent turbine stages. The high-pressure (HP) turbine powered the turbine‟s own 15-stage, axial-flow compressor. The low-pressure (LP) turbine drove another manufacturer‟s load compressor (Cooper-Bessemer, Nouvo Pignone, Dresser). These turbines were used primarily in the gas pipeline and petro-chemical industries and remain in popular use today throughout the world. Large gas pipeline companies (ex: El Paso Gas Company) and chemical companies (ex: Dow Chemical) purchased these turbines to drive variable-speed load compressors. The first generation of MS3002 gas turbines (a.k.a. Frame 3) delivered approximately 7,000 horsepower to the load compressor operating at approximately 6,000 rpm. Later models were rated at 11,000 hp at approximately the same speed. As the demand grew, designs improved to include a model series MS5002 (a.k.a. Frame 5) gas turbine. Most two-shaft turbines burn natural gas, because it was readily available at the plant. Fig. 8-1 shows a factory isometric view of a frame 3 gas turbine. The accessory base is in the lower right-side foreground. A tilted compressor inlet is shown in the center. Also, three of the six turbine combustors are shown on the far left, partially assembled. This configuration allowed for shipment on rail cars or trucks.
Fig. 8-1: Factory View of MS3002 Gas Turbine (circa 1968) Hundreds of GE Frame 3s are still used to deliver natural gas from the Gulf Coast of the USA to consumers in Northeastern and Central regions. Others are used in process industries in chemical plants, many of which are also along the coast from Texas to Louisiana. These turbines are also popular in oil refineries, most of which are located in the southern states.
Fig. 8-2: Diagonal Factory View of MS3002 Turbine on the “Half Shell” (circa 1973) Many MS3002 gas turbines were regenerative (R) cycle units. This type takes on the abbreviation MS3002R. Regenerative-cycle units became popular because of their improved thermal efficiency (i.e. reduced heat rate). A heat exchanger, like the one shown in Fig. 8-5, transfers exhaust heat to the compressor discharge air reducing fuel consumption.
Fig. 8-3: HP Turbine (left) and LP Turbine Stages Fuel consumption (that is, the BTU burned in each hour of operation) is divided by the horsepower (hp) developed in the load compressor to calculate heat rate: HR = BTU/HP-hour.
Variable-speed load devices (that is, compressors not generators) are best suited for using 2-shaft gas turbines. The two compressors, by design, typically operate at two different speeds. The variable-area, second-stage turbine nozzles (abbreviated: VASN), located between the HP and LP turbines, allow for the division of thermal energy between stages, so that each can operate at their respective optimal speed. Fig. 8-4 shows a side view of a MS3002 gas turbine. The turbine shell (see item #3 in the photo) shows the outer linkages and control ring of the VASN. These nozzles act as the energy divider between the two turbine stages. The hot gases from the combustion system pass through the HP section (Stage 1) before it continues through the LP section (Stage 2). The nozzles between the stages are controlled to optimize the division in energy per the speed setpoints for each shaft. The speed setpoints for the HP and LP turbines are determined by the horsepower requirements and the turbine exhaust temperature limit for the operating conditions of the particular time of day.
Fig; 8-4: Side View (#3 above shows Variable-area, Second-Stage Nozzles The schematic shown below in Fig. 8-5 shows a typical regenerative cycle gas turbine (plan and elevation views). Arrows depict the air flow to/from the regenerator and turbine exhaust. Study this diagram to better understand the gas flow and heat exchanged from the exhaust to and the compressor discharge air.
Fig. 8-5: Schematic View of Regenerative Cycle Gas Turbine (2 views)
Fig. 8-6: Schematic Diagram of typical simple cycle MS3002 Gas Turbine
Fig. 8-7: MS3002 Regenerator and Exhaust The petro-chemical industries of the world have successfully used 2-shaft gas turbines to drive load compressors for over 60 years. Most are regenerative-cycle turbines that allow exhaust heat recovery to minimize fuel consumption. Base load operation, where these turbines run 61
continuously during the plant manufacturing processes, or along the gas pipelines northward from the Gulf Coast, is the best application for efficient use. The General Electric designs described herein have been very successful. In recent years, GE purchased Nouvo Pignone of Italy to offer both the 2-shaft gas turbines and the load compressors in a “packaged” arrangement. Tags: Combustion, combustor, control systems, Gas turbine generators, gas turbines, regenerative cycle, regenerator
Peaking Power, Chapter 9: Enter the Peaking Package Power Plant In 1961, General Electric manufactured and installed the first package power plant (PPP) at South Carolina Electric and Gas. The PPP was primarily used for peaking and emergency power generation. The “packaged” concept was unique for the time: locating most of the primary and auxiliary components on the same I-beam base as the gas turbine during factory assembly. This allowed for easier factory testing, shipping to the site on rail cars or trucks and short-cycle installation in the field. The gas turbines were assembled on the same 36-inch I-beam base along with the accessory compartment. They were built in Schenectady, NY, where they were started and tested at full speed/no load (FSNL) on liquid fuel. The speed reduction gear and load generator were built in Lynn, MA, first meeting met the gas turbine at the installation site. There they were aligned and mechanically coupled. Electrical interconnections were typically by cable with multi-pin connectors (Pile National Plug or Canon). Control cabs were built in Salem, VA, so they were never tested with the gas turbine or generator until connected at the installation site for the first start-up. Below is a similar PPP installed at Central Vermont Public Service (CVPS) in Ascutney, VT.
Fig. 9-1- Control Cab and Accessory Compartment for MS5001D unit at Ascutney, VT (circa 1961) A few other packaged units, like the one shown above in Fig. 9-1 and 9-2 below, were sold and installed in such remote locations as Rutland, VT and Southampton, NY, the latter on the eastern tip of Long Island. And it‟s a good thing they were, particularly the one in the Hamptons. That lonely 12 MW peaking and emergency plant has been credited with bringing back Long Island in New York after the Northeast Blackout of November, 1965. The units in Rutland has been called upon to start at many other critical times when it has gotten hot in the summer. Yes, the Green Mountain State can get hot in July and August! 63
All these “old dogs” were available to run during preparations for the end of the millennium and the Y2K expectations of computer glitches taking down the power grids. This event never occurred, but the gas turbines were ready to perform, if needed. They are approaching 50 years of operation in 2011. The Southampton turbine is essentially “as built,” with virtually all its original controls and auxiliary systems. It still has the original controls and auxiliaries, including the fuel regulator. See Chapter 7 herein.
Fig. 9-2- Side view of Inlet and Turbine Compartments at Ascutney, VT (circa 1961) The MS5001D units in the early 1960s were rated at 11,250 KW at NEMA conditions (compressor inlet of 80 ºF at an elevation of 1000 feet, which relates to an ambient pressure of 14.17 psia). As the decade of the sixties continued, only a few GE units were sold prior to the 1965 Blackout (an average of just 4 units per year). The MS5001 evolved to the model “K” by the time the lights went out in 1965, and were then rated at 14,000 KW when fired at 1500 ˚F. The so-called “L” and “LA” Frame 5 turbines came in the late 1960s. They were rated approximately 15,000 KW and fired at 1650 ºF. Many were dual fuel and they were often configured in two or fourunit power blocks (PB). In these cases, the starting means of at least one of the turbines was by diesel engine. If the control cabs were not “stand alone” and on the end of the accessory bases, the plants often “shared” many auxiliaries like batteries, CO-2 fire protection systems and fuel forwarding skids. For instance, at Buzzard Point in Washington, DC, there are four 4-unit blocks. They are configured in two rows of eight units and the two control cabs are in the center of the site and connected at both ends, allowing the operator to remain inside one structure to start all 16 units.
Fig. 9-3- Four-unit Power Block MS5001L installed at PPL in Allentown, PA (circa 1967) The packaged unit shown in Fig. 9-4 below was installed in Astoria-Queens, NY. Notice the elevated foundation because of its proximity to the East River at the ConEd (Now US Powergen) plant. This MS5001LA was rated at 15 MW at its sea level location.
Fig. 9-4- MS5001LA PPP installed at ConEd Astoria-Queens, NY (circa 1970) Green Mountain Power installed a MS5001J plant in 1966 near a hydro plant in Winooski, VT. The 12 MW plant at The Gorge was (and likely still is) the only gas turbine in northern Vermont. Fig. 9-5 is viewed from above on the hill from the generator end.
Fig. 9-5- Generator end of MS5001K PPP at Green Mountain Power, Winooski, VT (circa 1966) Call it lucky or call it fortuitous. General Electric innovated the “black start” package power plant (PPP) concept in 1961 and brought it into production. The model “D” machines evolved to the “K” by the middle of the decade. Thus, GE had a good product when the Northeast Blackout hit in November 1965. If you believe in conspiracies, the Gas Turbine Department later evolved into a full GE company division. This kind of electric power producer became the product of choice for many utilities, refineries and gas pipelines in the decades that followed. Could the Blackout have been caused on purpose? We doubt it, bu who knows? Read Chapter 10 about the day the lights went out and you decide. This posting will come in September 2011. That is, unless the power goes out!
Peaking Power, Chapter 10: The Great Northeast Blackout On November 9, 1965, the northeastern United States experienced a severe power outage. It came to be known as The Great Northeast Blackout, as many states experienced a power blackout lasting up to twelve hours. The term “black start” capability is common in the power generation industry. It came into prominence this suddenly dark day in America. After exhaustive investigation, the cause of the blackout was determined to be a failure that originated at the Niagara Falls generating station called Sir Adam Beck Station No. 2 in Queenston, Ontario. It was a cold November evening and power demand for heating, lighting and cooking was stretching the power system to its peak capability. At 5:16 p.m. Eastern Time, a small surge of power coming from Lewiston, New York‟s Robert Moses generating plant “tripped” an incorrectly adjusted protection relay. This relay was supposed to prevent the power line from being overloaded. The resulting action disabled a main line heading into Southern Ontario at far below the line‟s rated capacity. Within a few seconds, the other lines departing north out of the plant were overloaded by the excess power flowing into them and their relays also tripped. This isolated Adam Beck from all of Southern Ontario. The excess power from Adam Beck then headed toward the interconnected lines heading south into New York State. This action overloaded the lines as well and isolated the power generated in the Niagara region from the rest of the interconnected grid. The generators, with no available outlet for their power, were automatically “tripped” to prevent the decreasing frequency from damaging their systems. Within five minutes, the power transmission system in the entire northeast was disrupted and chaos ensued, as the effects of overloads and loss of generating capacity “cascaded” through the network. These smaller systems became “islands,” as plant after plant experienced load imbalances and automatically fell off line. The affected power areas were the Ontario Hydro System, St Lawrence-Oswego, Western New York and Eastern New York and most of the six New England states. Note: Many Americans thought the blackout was an attack by the Soviets. The humiliation Nikita Khrushchev must have felt after the President Kennedy made him back down during the Cuban Missile Crisis of October 1962 naturally made Americans think this might be an act of retribution. Though it turned out to be untrue, many across the USA feared we were at war. Maybe even nuclear war! Sometime later the next day, in the hamlet of Southampton on tip of Long Island, a GE gas turbine-generator was called upon to start. It was owned and operated by Long Island Lighting Company (LILCO). It could start without outside AC power, because it had an ample supply of #2 distillate fuel in a nearby storage tank. Also, its 125-volt DC battery system was fully charged and the diesel cranking engine, clutch and ratcheting mechanism functioned perfectly. It took approximately 8 minutes from the time LILCO operators initiated a “black start,” until it reached synchronous operation. It then had to be synchronized to a „dead bus,” it had this capability. Soon breakers were closing and power was being back-fed to the LILCO Port Jefferson steam plant. Hours later, the rest of the Island power grid was restored.
Fig. 10-1- Package Power Plant at Central Vermont Public Services (circa 1961) Yes, this tiny General Electric 12-megawatt MS5001D gas turbine/generator (similar to thte one in Fig. 10-1 above) helped bring back the entire LILCO system. Years later in the decade, such mammoth power companies as Consolidated Edison Company of New York (ConEd), Pennsylvania Power & Light (PPL) and of course, LILCO, added hundreds of gas turbinegenerators to their fleets. For example, ConEd purchased forty-eight MS5001N units, rated at 20 MW each, and installed them on floating power barges in the East River in Brooklyn, NY in 1971. At the Gowanus and Narrows plants, each 4-unit power blocks have at least one gas turbine with a diesel starting engine. The total rating of the ConEd power blocks is nearly 1000 MW of “emergency” or peaking power to the NY City region. To date, the barges remain afloat with standby power service forty years later! During the nine years between November 1965 and the Arab Oil Embargo of 1973-74, electric utility companies throughout North America purchased and installed hundreds of package power plants by GE, Westinghouse and Pratt Whitney. Most remain in standby service to this day. In the decades that followed, combined-cycle and co-generation power plants (gas turbines with heat recovery boilers to make steam for these turbines) became the better, more efficient application. More on this in a later chapter.
Fig. 10-2- Typical MS5001L 4-unit Power Block – PEPCO – Washington, DC (circa 1968) Believe you may, that this event forty-five years ago was a conspiracy by General Electric to sell gas turbines, but that myth has been rightfully disproven. At least that‟s what we‟ve been told. And who would doubt a story coming from the company some call The General? Tags: Adam Beck, Blackout, Gas turbine generators
Peaking Power, Chapter Eleven: The Long-awaited Frame 7 In 1971, General Electric finally offered a power plant of the size that most electric utilities wanted 6 years earlier after the Northeast Blackout of 1965. It was called the model series MS7001 package power plant. Also known as the Frame 7, it was rated approximately 40 megawatts, making it nearly three times the generating capacity of a MS5001J (frame 5) at the time of the Blackout in 1965. This pleased many utilities. The first MS7001A (S/N 214053) was manufactured in Schenectady, NY. After significant testing, it was sold and installed at Long Island Lighting Company in West Babylon, NY. A bevy of other Frame 7s units soon followed. Those were designated the MS7001B power plants, they were all built at GE‟s new facility in Greenville, SC. Notable power companies as Philadelphia Electric, Houston Lighting & Power and Florida Power & Light, Florida Power Corp, Tennessee Valley Authority and Georgia Power purchased hundreds of Frame 7s in the middle to late 1970s. Replacing the Frame 5 as the unit of choice, GE finally offered a peaking power plant of the rating wanted by most electric utilities desired. However, the Arab Oil Embargo of 1973-74 would soon change the entire climate of gas turbine power generation. Fig. 11-1 below shows a typical MS7001B power plant in Greenwood, Missouri (installed circa 1975). This unit is rated approximately 50 MW. The rated speed for the turbine and generator was 3600 rpm. Driving a 2-pole, air-cooled generator, this meant that 60-cycle power could be delivered without the need for reduction gearing as is required on the Frame 5. The Frame 7 retained many of the design features made popular with the Fame 5. It was a modular design. The generators were manufactured in Lynn, Massachusetts, meaning that they never met the gas turbine until at the installation site. The accessory base was separate too, so the interconnections (electrical, mechanical, pneumatic and hydraulic) were done for the first time at the jobsite.
Fig. 11-1- General Electric MS7001 (a.k.a. Frame 7) gas turbine at Greenwood, MO
For visual effect, as shown in Fig. 11-1 and 11-2, appearance lagging was installed around the major components to make the site more appealing to the passersby. This was particularly important for the exhaust stack which often rusted and become an eyesore because of its needed height (see left of Fig. 11-1). Fig. 11-2 below shows a typical MS7001E power plant in Pleasant Hill, Missouri (installed circa 1980). This unit is rated approximately 65 MW.
Fig. 11-2- General Electric Frame 7E (a.k.a. MS7001E gas turbine) One distinguishing feature of the Frame 7 is the turbine section. It has three stages as shown in Fig. 11-3 below. Each stage has nearly 100 blades (a.k.a. at GE as buckets) to develop the power to the aft turbine stub shaft which is bolted at the flange to the generator rotor.
Fig. 11-3- Three-stage Rotor for GE MS7001B Gas Turbine 71
A seventeen-stage compressor rotor was developed for the Frame 7 to increase air flow and deliver higher compressor discharge pressure to the combustion system. See Fig. 4.
Fig. 11-4- Seventeen Stage Compressor Rotor and Three Stage Turbine Most of the auxiliaries required to support the operation of a Frame 7 (shown in Fig. 11-5) are all installed on a separate accessory base. The accessory gear box, shown on the left, drives such auxiliary pumps as the main lube oil, main hydraulic supply pump and the positive-displacement fuel pump. The power to drive the gear comes from the cranking motor (during start-up) and the gas turbine itself (during operation). The motor control center, with motor starters for such secondary pumps as the auxiliary lube oil, water pump and hydraulic supply pump, is typically on its own skid and installed at the front of the accessory compartment.
Fig. 11-5- Accessory Base for MS7001
Fig. 11-6- Accessory Gear for a MS7001B The accessory base has many auxiliary devices used to support the operation of the gas turbine. There are many devices driven by the accessory gear of a frame 7:
Lube oil pump Atomizing air compressor (on some turbines, if applicable) Hydraulic supply pump Liquid fuel pump (if applicable)
Fig. 11-7- Two Views of Accessory Gear Cutaway for a MS7001B Frame 7 gas turbines are always started with electric (cranking) motors. The schematic drawing (Fig. 11-8) below shows a motor (called 88CR). It has a flexible coupling on the output shaft connecting to a torque converter. A starting atomizing air (AA) compressor is identified. It was belt-driven by the starting motor to provide compressed air for atomization of the fuel during the firing, cross-firing and acceleration periods of the start-up. Once the overriding, jaw-clutch disengages (approximately 60% speed during start-up), a motor-driven AA compressor located on an off-base skid had to be operational. If “black start” capability was required at the site, a separate diesel generator was utilized to provide power to the starting motor (88CR) and the off-base auxiliaries including:
Fuel forwarding pump AA compressor Cooling water pump, AC lube oil pump 480 volt AC battery charger
Fig. 11-8- Starting Means (Electric Motor) for a MS7001B The Frame 7 typically gas turbine had several off-base, skid-mounted auxiliaries:
Liquid Fuel Forwarding (similar to the frame 5) Atomizing Air Cooling Water CO-2 Fire Protection Compressor Water Washing Water or Steam Injection
These auxiliary systems were connected to the turbine control panel and motor control center. The MS7001B can be said to have “saved” GE‟s Gas Turbine Division, because it met the demand for emergency power in the USA and Canada, as well as larger islands like Puerto Rico. This design has evolved to the MS7001EA forty years later, doubling its original power output to 80 megawatts. Tags: Arab Oil Embargo, Atomizing Air Compressor, Blackout, Florida Power & Light, Florida Power Corp, Frame 5, Frame 7, Gas turbine generators, gas turbines, Georgia Power, Great Northeast Blackout, Houston Lighting & Power, Hydraulic Supply Pump, Liquid fuel pump, Long Island Lighting Company, Lube oil pump, package power plants, Philadelphia Electric, Schenectady, Tennessee Valley Authority, turbines
Peaking Power, Chapter Twelve: The Mighty MS5002 Gas Turbine The two-shaft gas turbine was first introduced in the 1950s. They showed some popularity in gas pipelines and chemical process plants in the 1960s, where variable-speed load compressors (made by manufacturers other than GE) were required. These load compressors were designed to operate at speeds different than the gas turbine‟s own axial-flow compressor. In 1970, an affiliate of General Electric named Nouvo Pignone of Florence, Italy (now owned by GE Oil and Gas) began manufacturing the MS5002A. In response to market demands, the socalled Frame 5-2 has undergone upgrades including models B, C and the current D. The D model has a heat rate of 8,650 BTU/HP-hr for a rated 43,000 HP delivered to the load compressor shaft Forty years after the 5-2 was first introduced, Nouvo Pignone‟s achievement parallels its related accomplishments in load compressor designs in package plant concepts. In short, they can provide both the gas turbine and load compressor together, giving them an excellent competitive advantage. In Chapter 8 of this blog, we reported on the predecessor, the MS3002 gas turbine, the first was a 5-bearing unit. The latter frame 3-2 design revealed in 1970 had only four bearings, two per shaft. Even from the start, the larger 5-2 gas turbine was far more refined than the 3-2, taking some of the features of the latter design Frame 3. The MS5002 was first offered more than 40 years ago, taking its axial-flow compressor design from the MS5001N (so-called Nancy machines) for generator drive applications. In 1987, the MS5002B output was upped to 38,000 HP in MS5002C, through the use of “advanced materials and design features that were more resistant to high temperature damage and wear,” according to GE. The MS5002D gas turbine represented the joint-venture efforts of both GE and NP. In the latest design, GE took the success of MS6001B compressor, a “slightly modified 17-stage compressor” with newly designed rotor and stator blading and related casings. This increased airflow and hence pressure ratio and, of course, power output.
Fig. 12-1- Colored Cross-section of MS5002 Gas Turbine
Figure 12-1 above, depicts an accessory base on the left set lower than the gas turbine. This is a regenerative cycle MS5002B with the heat exchanger (regenerator) shown with the two pipe flanges in the center. The accessory base shows the expansion turbine starter and accessory gear on a pedestal. Tags: Compression, gas turbines, MS5002, Nouvo Pignone, regenerative cycle, two-shaft
Peaking Power, Chapter Thirteen: Speedtronic™ Control and Protection Systems
Fig. 13-1- Speedtronic™ Mark I logo on gas turbine control panel General Electric unveiled its first electronic control and protection system in 1970. It was called Speedtronic™. Other manufacturers similarly introduced electrical and electronic controls on gas turbines at the about same time. The name for GE‟s system came from the combination of Speed control by elecTronic. I‟ve had difficulty confirming who came up with the name, but it has prevailed for over four decades up to modern times. The first generation was called Mark I. GE currently offers the sixth version, Mark VIe, a computerized version that will be discussed in later chapters.
Fig. 13-2- Speedtronic Control Panel – Lights and Selector Switches
Fig. 13-3- Typical Speedtronic™ Mark I Panel (mounted on test dolly) The first gas turbines to utilize Speedtronic™ controls to drive generators were the MS5001M and MS7001A turbines as prototypes in 1969-70. Several so called “Mary” machines, as the frame 5‟s were nicknamed, were typically sold in 4-unit power blocks. Most notable were the eight turbines installed by Niagara Mohawk in nearby Rotterdam, NY, only a few miles west of the GE plant in Schenectady. I believe the very first Mary went to Public Service on New Hampshire in the northern part of the state. Long Island Lighting purchased the first “7A” machine, after considerable testing of this “first of a kind” was done at the Schenectady Works 79
plant. It was installed at the Shoreham site on Long Island. It was the only Frame 7 ever built in Schenectady. In 1971, the first MS5001N machines (frame 5 nicknamed “Nancy” machines) and MS7001B turbines were commissioned with Speedtronic™ controls. Many 5N turbines were sold in their first year of production: for instance, Consolidated Edison Co. purchased 48 of them for floating power barges in the East River in Brooklyn, NY at the Gowanus and Narrows sites. Many others were installed at utilities in the USA, particularly in small towns. For instance, Pennsylvania Power & Light operated a 2-unit power block in Sunbury, PA and installed a 4-unit power block in Martins Creek, PA in that year. All had Mark I controls. The 7B machines were very popular also as hundreds were sold to electric utilities and industrial power generation plants in the USA and abroad mainly because of the higher generating capacity. Venezuela‟s government-owned power company called CADAFE purchased many 7B machines, as one of GE‟s most important international clients. A typical Speedtronic™ panel for a 7B is shown in Fig. 13-3. In the next photo, Fig. 13-4, the electronic circuit boards are shown configured in rows and columns. Approximately 70 circuit boards were required, depending upon the model and features of a particular turbine. Dual fuel systems used the most controls circuit boards with diesel engines and “black start” capability required the most boards.
Fig. 13-4- Typical Speedtronic™ Page 1L showing as many as 70 circuit boards Also known as “cards,” the circuitboards were configured into rows (top to bottom) and columns (A-T., right to left). As Fig. 13-5 shows, there are many different types of boards with different fascia, depending upon the function of each. All cards had 51 pins on the back plane for electrical wire connections. This door was referred to as the Speedtronic™ Page, as it
resembled a page in a book. The Page was called Page 1L in the turbine electrical elementary drawings.
Fig. 13-5- Row 1 on a typical panel showing various types of circuit boards Many of the circuit boards were in existence when applied to gas turbines, originally used in commercial systems and manufactured at GE‟s Salem, Virginia plant. The generic name was Directomatic II for the cards. Popular cards included: input buffers, operational amplifiers, relay drivers, light indicators and clock drivers. Other cards, as shown in Fig. 13-5, had to be specially made for gas turbine applications, for instance: SSKA was used for gas turbine start-up control, with all the red test buttons shown on the left in position page 1L, row 1, column P. This location was usually abbreviated simply: [1L1P]. This card sets fuel limits by setting a control signal called Variable Control Voltage (VCE). Note: voltage is also known as electromotive force (EMF). Thus, the letter is E in the abbreviation, instead of V. In Fig. 13-5 above, notice the cluster of green cables at the right. They provided the interconnections to outside signals, including the relay page called 2L. It is shown on a door behind the Speedtronic™ door below in Fig. 13-6. There are approximately 50 DC relays (shown in the middle, brown in color) and a dozen timers (shown at the top). They are configured in rows (0-7, top to bottom) and columns as well. The relays are the “plug-in” type and can be replaced if necessary should one fail in operation. The timers are adjustable and serve many applications where a timed operation is required. For instance, the hydraulic ratchet on a MS5001N machine has a 3-minute cool-down cycle, hence the setting of timer 2HR.
Fig. 13-6- Relay Page “2L” showing as many as 50 relays and timers
The Speedtronic™ panel could be calibrated by field engineers, as shown in Fig. 3-7. A special calibrator tool was provided by GE that could be connected into the panel, as shown. Dave Lucier, of PAL Turbine Services, LLC, performs a calibration for Aquila in Jefferson City, MO. It provided both analog and digital signals for speed, temperatures and DC voltages that are used as “inputs” to circuit boards shown in the lower half of the panel in Fig. 3-7. The calibrator could also be used to simulate operation of the gas turbine when desired.
Fig. 13-7- Senior Field Engineer, Dave Lucier, calibrates Speedtronic panel Most control systems of this era were also accompanied with a protection system that included an annunciator as shown below in Fig. 13-8. A lamp would flash and an audible sound would alert the plant operator should an adverse condition arise or a shutdown signal be initiated. Crude by modern standards, this type of system was very common during the 1970s era. Tag names on the annunciator light would alert the operator as to the problem; from there, the operator could consult an instruction manual so and take the action required.
Fig. 13-8- Typical 40-drop Annunciator for Alarm and Trip Functions Certainly crude by modern standards, Speedtronic™ Mark I and Mark II were offered by General Electric for decade of the 1970s. The technology can be traced to the developments in analog and digital controls that evolved in the late 1960s, perhaps as a consequence of the space race that lead to men landing on the moon in 1969. General Electric was certainly a pioneer in the application of these developments to gas turbines. 83
Tags: Consolidated Edison Co., control systems, Control Sytems, gas turbines, Mark I, Mark II, MS5000, MS5001N, MS7001, MS7001B, Page 1L, Speedtronic™, turbines
Peaking Power, Chapter Fourteen: The Arab Oil Embargo of 1973 – 1974 Leave a comment » Beginning In fall of 1973 and extending into the early winter of 1974, oil producing nations of the Middle East and South America imposed an oil embargo on the United States and its western allies. This resulted in a serious blow to their economies in general and to gas turbine manufacturing in particular for the rest of the decade. The oil crisis officially began on October 17, 1973. Members of Organization of Petroleum Exporting Countries (OPEC), consisting of the Arab members, Venezuela and other supporters of Egypt and Syria, decided to punish the USA for supporting Israel in the ongoing Yom Kippur War. OPEC members agreed to use their world-wide, price-setting power to raise oil prices, after attempts at negotiation with the “Seven Sisters” earlier in the month failed (see below). Due to their thirst for OPEC oil, soaring prices were dramatically inflationary to the American and European economies, stifling economic activity. To counteract this attempt at “black mail,” targeted countries responded with a wide variety of new, and mostly permanent, initiatives to contain their further dependency on foreign oil. Also, it can be said that the Northeast Blackout of November 1965 and the OPEC oil embargo of October 1973 formed “bookends” on the gas turbine power generation business. Fig. 14-2 shows a “black start” unit owned by Green Mountain Power (GMP) at Winooski, VT installed circa 1967 with two (white and primer red) oil tanks nearby.
Fig 14-1- Distillate #2 fuel oil tanks tower behind gas turbine at GMP in Winooski, VT Dubbed by an Italian entrepreneur, Enrico Mattei, the so-called Seven Sisters, were comprised of seven huge, multi-national oil companies. After the breakup by the US Government of Standard Oil monopoly earlier in the 20th century, several new companies were created. With their virtual 85
monopoly on oil production, refinement and distribution, they were able to take advantage of the rapidly increasing demands for oil products and turn huge profits. Being well organized and able to negotiate as a cartel, members were able to have their way with most Third World oil producers. However, Seven Sisters‟ influence declined when OPEC challenged them, as the Arab states and Venezuela tried to wrest control over oil prices and production, The so-called Seven Sisters oil companies included: 1. Royal Dutch Shell 2. Standard Oil of New Jersey (Esso). This later became Exxon, now ExxonMobil. 3. British Anglo-Persian Oil Company (APOC). This later became British Petroleum (BP), then BP Amoco following a merger with Amoco (which in turn was formerly Standard Oil of Indiana). 4. Texaco. This later merged with Chevron and was Chevron-Texaco. The company has reverted back to just Chevron. 5. Standard Oil of New York (Socony). This later became Mobil. 6. Standard Oil of California (Socal). This became Chevron. 7. Gulf Oil. Most of this became part of Chevron, with smaller parts becoming part of BP. Gas turbine sales in the United States plummeted in the middle to late 1970s. For instance, GE sold about 800 gas turbine/generators in the previous eight years. At its sales peak around 197071, GE was shipping about two package power plants per week out of their two factories in Schenectady, NY and Greenville, SC. One client, Consolidated Edison Company (ConEd), purchased 48 package power plants at their Gowanus and Narrows barge sites on the East River in Brooklyn, NY. After the oil embargo began, sales fell to a handful of units per year.
Fig. 14-2- GE MS5001L gas turbine-generator at ConEd facility at Astoria Queens, NY. (circa 1970)
Fig. 14-2 above shows a typical MS5001L package power plant installed at the ConEd generating station in Astoria (Queens), New York in 1970. The unit had a “black start” diesel starting engine, but operated on a single fuel (natural gas) with a rating of 15 megawatts (NEMA conditions) at its sea level location near the East River in Astoria Queens, NY. Even new-unit installations at international locations suffered in the 1970s due to the high cost of imported fuel oil required by gas turbines. Caribbean nations, like Aruba, Curacao, St. Thomas, St. Croix and Jamaica, continued to order the smaller MS5001P gas turbines in the middle of the decade due to power shortages on resort islands. Some islands had their own refineries. Larger countries like Puerto Rico and Venezuela had high enough power demands to warrant the larger MS7001B & C power plants. Turbine manufacturers like GE and Westinghouse could be thankful that there was still some international demand for gas turbine generators in the late 1970s, despite the lingering effects of the Arab Oil Embargo.
Fig. 14-3- MS5001P Package Power Plant at St. Thomas, USVI (installed1980)
Fig. 14-3- MS5001P Package Power Plant at St. Thomas, USVI (installed1980) The gas turbine in Fig. 14-3 is a MS5001P-NT installed in 1980 in St. Thomas, USVI. It was upgraded with new-tech parts in the year 2000 to increase power output and to add a heat recovery steam generator (HRSG) to recover the exhaust heat for steam generation. The steam
plant is located in the blue building behind it with the tall stack. A generator-end view of the upgraded plant appears in Fig. 14-4 above. Now for a personal story: In the spring of 1973, I was supervising a major overhaul of a unique General Electric gas turbine installed in the Shell-Amuay refinery on the Paraguana Peninsula in Venezuela. Amuay was the largest oil refinery in South America at the time. This turbine was very unique (MS5001A) because it was a “cold end” drive unit installed in 1958. The generator was driven on the compressor end of the turbine. The exhaust end was nearby the accessory gear box that drove some other auxiliaries like the lube oil pump, water pump and a fly-ball governor. Yes, a rotating pilot valve type fly-ball governor on a gas turbine! The controls were affectionately called “links and levers.” It seems that refinery owners did not want any electro-hydraulic controls like those of the fuel regulator (see Chapter 7 herein) because of their fear of fires. This design was very unique for GE gas turbines. In June of that year, we completed the reassembly of the turbine and I returned to the USA, as this was my final field assignment for GE. My wife and I settled in western Massachusetts. After a brief leave of absence from GE to consider graduate school, I returned to work as a product test engineer at GE‟s Mechanical Drive Turbine Department (MDTD). The commute from Belchertown to Fitchburg was about 50 miles each way, so I bought a Volkswagen “fast back” to get better mileage. Little did I know how fortuitous that purchase would be in October. Gasoline prices and shortages would be somewhat mitigated by my 30 mpg VW! Remember the annoying 55-mile per hour speed limit in the 1970s? The Eisenhower interstate highway system, with trucks roaring past obedient motorists, was indeed scary! Confession: At the height of the crisis in Massachusetts, commuters who had odd numbered license plates were allowed to purchase gasoline only on the odd-numbered days of the month. Drivers with even-numbers were, in turn, limited to even-numbered days. I confess that I often temporarily swapped license plates with my wife‟s Chevrolet Camaro some days, just so I could fill up the VW with gas. On some days, filling stations only allowed one dollar‟s worth of gas! Worthy of Note: most of the imported gasoline and heating oil coming into the New England states in this decade came from the Venezuelan-owned company known as Citco. So get this, in the first part of the year in 1973, I was overseeing the overhaul of a vital power generator at the largest refinery in South America; by year‟s end, I was sitting in a lines to purchase few bucks worth of Citgo gas! In short, I do not subscribe to the LIE that there was truly a world-wide oil shortage! The tankers I saw idling off Paraguana Peninsula awaiting product from Amuay convinced me of that. The energy crisis in the 1970s was devastating to the USA. It eventually lead to the defeat of President Jimmy Carter for a second term in 1980. Ronald Reagan, reaped the benefit of high inflation and the negative politics accompanied it. What followed was a serious recession early in the next decade.
Little Known Fact: President Carter (an engineer in a previous life) challenged America to develop a national energy policy after the OPEC fiasco in the 1970s. He was shunned by the Congress due to high inflation and America‟s continued dependency on fuel oil for home heating and gasoline for automobiles. He wanted to expand drilling in locations such as Alaska and the Gulf of Mexico. Final Comment: Nearly four decades have passed since the OPEC embargo of the 1970s and America still does not have a national energy policy. Presidents have come and gone since Carter‟s challenge: Reagan, Bush the Elder, Clinton, Bush the Younger and currently Obama. Presidents have only two tools to motivate the American people: patriotism and fear. We should fear the influence and control of imported energy. Also, we should follow emotion of patriotism to get a policy passed in Congress. Tags: Amoco, APOC, black start, BP, Chevron, Enrico Mattei, ExxonMobil, Gulf Oil, Mobil, MS5001P, MS500L, OPEC, Royal Dutch Shell, Seven Sisters, Standard Oil, Texaco
Peaking Power, Chapter Fifteen: Cogeneration and Combined Cycle In the early 1980s, General Electric recognized an emerging market for gas turbines called cogeneration (co-gen). The MS6001B (a.k.a. Frame 6B) was introduced at this time to meet the demand. In co-gen applications, the 6B provides exhaust heat to a heat recovery steam generator (HRSG). This allows steam generation for a “host” company located next door and a secondary “by product” called electricity. Thus, its primary purpose was to deliver low-pressure steam next door for a completely different industrial purpose. In upstate New York, Frame 6B plants were installed next door to several paper mills, a Morton Salt plant, and even the Remington Fire Arms manufacturing plant. The high-pressure steam (typically 900 F at 800 psig) generated by the HRSG was sent to a separate steam turbine in the co-gen facility, acting as a pressure reducing station. After passing through several turbine stages, some steam flow was then sent to the “host” next door, typically at a pressure in the range of 200 psig. The remaining steam flow continued through the low-pressure turbine stages to the condenser. Both gas and steam turbine generators were connected to an electrical grid. The 6B gas turbine was considered to be kind of a hybrid between two Frame Sizes: 5P and 7C. The 17-stage compressor in the 6B was similar to that of the 5P; however, the turbine section was more like a 7C, with its three turbine stages. In the combustion area, the design of the 6B closely resembles its smaller predecessor the 5P, except that the ten combustions are “canted” to shorten the overall length and preclude the need for an intermediate bearing to support the rotor like that of the 7C turbine. Also, the early 5P and 7C turbines utilized the familiar straight-through combustors, running in parallel with the rotor centerline. Fig. 15-1 below shows an elevation view of a turbine rotor installed in its lower-half casings. The rotor is resting on its journal bearings (fore and aft), with the three turbine stages on the left and the 17-stage compressor on the right. This is a factory view from above often referred to as “rotor on the half shell.”
Fig. 15-1- Areal View of MS6001B with Upper Casings Removed and Rotor in Place (circa 1985) In Fig. 15-2 below, the rotor is supported by temporary bearings in a balance machine, where it can be spun at a low speed (typically 200-300 rpm). Although the turbine blades (called buckets 90
in GE parlance) are “moment weighted” for pre-balance, a dynamic test is required to assure that the amount of tolerable unbalance (measured in gram-inches) is met before the rotor is installed in the turbine casings.
Fig. 15-2- Factory View of MS6001B Rotor in Balance Machine (circa 1985) A more modern gas turbine (MS6001FA shown in Fig. 15-3 below) is ready for transport from the factory in Greenville, SC. Notice that the combustors are not yet installed nor are many of the extraction cooling and sealing air pipes from the axial-flow compressor.
Fig. 15-3- Modern MS6001FA gas turbine (circa 2000) Fig. 15-4 below shows a Frame 6FA rotor in its lower half casing as viewed from the compressor inlet end. Lower half inlet guide vanes are shown in the bellmouth.
Fig. 15-4- Modern MS6001FA axial-flow compressor and inlet guide vanes (circa 2002) In Fig 15-5, a factory assembler checks radial clearances on the #1 bearing forward seal at the compressor end of a Frame 6B gas turbine.
Fig. 15-5- Modern MS6001 gas turbine #1 bearing clearance checks The MS6001 gas turbine is no longer made at the Greenville, SC plant. They are, however, manufactured in Europe at one of GE‟s affiliates. Also, spare parts are made abroad for existing turbines installations in the USA. Companies other than GE also offer replacement parts in competition with the OEM. With the advent of the Frame 6B in the early 1980s, GE also offered a computer-based control system called Speedtronic™ Mark IV. A photo of a typical panel and control functions is shown in Fig. 15-6. Crude by today‟s standards, this was considered a “state of the art” control system in the early 1980s.
Fig. 15-6- Speedtronic™ Mark IV Control Panel Also, in the early 1980s, General Electric recognized another emerging market for gas turbines: combined cycle (CC). They had applied gas turbines to CC in earlier years. However, the MS7001E (a.k.a. Frame 7E) was reapplied to generate power, as well as to provide exhaust flow to an HRSG to create steam for a steam turbine. Note: The CC plant differs from the Co-genin that steam in the former system is not sent outside the plant for some nearby industrial process. The design of the 7E closely resembles predecessors (7B & C) of lesser power generating capacity. However, the 7B had longer combustors that ran parallel to the centerline similar to the one shown below in Fig 15-7.
Fig. 15-7- MS7001E Colored Cross-sectional Rendering Sometimes the steam and gas turbine shafts were co-linear, with the generator in the middle of the drive train (dual end drive). This configuration (gas turbine-generator-steam turbine) was known as Steam Turbine And Gas (STAG). See Fig. 15-8 below for the 9E turbine. One of the most famous combined-cycle (CC) installations was a plant located in Futsu, Chiba prefecture in Japan. Tokyo Electric Power Company (TEPCO) reclaimed approximately 4 square miles of land from Tokyo Bay and installed fourteen MS9001E combined-cycle power plants that eventually generated over 2,000 MW in 1998. At the time, it was the largest CC plant in the world. Might still be.
Fig. 15-8- MS9001E Colored Rendition – Accessory Base and Turbine In 1983, I joined the installation team at TEPCO on assignment for the installation of the first seven STAG 109E power plants. A total of fourteen Frame 9E units were eventually installed over a five-year period. Start-up came in 1988, on schedule, of course. Note: The Japanese had a charming habit of changing their schedule so they were always precisely on time. It would be an embarrassment to be either ahead of (or behind) the published “planned” schedule in any Japanese business venture. Most Americans would have just shrugged and responded: “ No big deal?” I served as the on-site service manager for General Electric Technical Services Company (GETSCO)and lead technical advisor for most of the first two years. My staff included:
Alfred Shuman, senior gas turbine technical advisor (TA) Bill Romizer, senior steam turbine and generator TA. Tom Hamilton, senior TA for the HRSG boiler installations Dave Smith, senior start-up TA for the Speedtronic™ Mark II controls
Fig. 15-9- Part of the GETSCO staff at TEPCO-Futsu (exhaust towers in background)
The TEPCO project was enormous. We had a total of GE 15 technical advisors at the site and a grand total of twenty on the GE staff, including office help. The client had hundreds of employees, as was the norm for Japanese firms. Also, GE affiliate companies, Hitachi and Toshiba, each built one complete unit (gas and steam turbines and their respective generators) in their Japanese factories. General Electric built 12 complete plants. All HRSG were built in the USA. Mitsui provided the interface between the Americans and the Japanese. Then this is what happened: After nearly two years in Japan, I returned to the USA in the spring of 1985. My first year back in the USA was spent “soul searching” and I eventually resigned from GE in 1986. I started my first company, I&SE Associates of Schenectady, Inc., on the Monday after my last day with GE. The letters I&SE were a takeoff on the original GE turbine service group that they changed in 1980 called: Installation & Service Engineering, hence then letters I&SE. Note: I‟m sure some people at GE minded that I did this, but my company was such “small potatoes” that nobody called me on it. Heck, if GE didn‟t want to call their service engineering by that name anymore, I figured I would. It served me well for a dozen years into the late 1990s.
Peaking Power, Chapter Sixteen: Computerized Control Systems In the early 1980s, General Electric introduced the Integrated Temperature System (ITS) version as an option for Speedtronic™ Mark II. It was GE‟s inaugural venture into the use of computers to control gas turbines, abandoning some of the standard integrated circuitry of Mark II from the previous decade. ITS dealt primarily with exhaust temperature signal conditioning, control and overtemperature protection. Only a few turbines went out the door with the ITS system, being offered exclusively on MS7001E gas turbines. Puget Sound Energy (PSE) purchased four ITS machines sites in Washington State. Also, Massachusetts Municipal Wholesale Electric Company (MMWEC) in Ludlow, MA purchased five 7E units. Sales were short lived. GE never officially referred to the system as Speedtronic™ Mark III, but some people thought of it that way. Not long after the ITS system arrival in 1982, GE offered its first fully-computerized control system.. Continuing the theme, it was called Speedtronic™ Mark IV. See Fig. 16-1 below.
Fig. 16-1- Speedtronic™ Mark IV Control Panel The Mark IV system lasted most of the decade of the eighties. It included a Triple Modular Redundant (TMR) concept that was a significant departure from the Mark I and Mark II systems of the 1970s. Mark IV offered three main controllers that “voted” when assessing critical operations. In many decisions, 2/3 voting was required to trip the gas turbine and shut it down. In earlier Mark I and Mark II, most systems were “simplex” in concept; others were redundant but were “either/or” in operation. For instance, if one of the overspeed sensors measured excessive speed on a Mark II, the turbine would shutdown.
In Mark IV, all of the controllers (known then as microprocessors) had to be “healthy” to allow the turbine to start initially. However, the turbine could operate on just one controller, if necessary. The three controllers were called “R”, “S” & “T”. This was written when a function involved all three processors. Also, so-called Communicator was required; it permitted communications between . If a function applied to only one controller, the R processor for instance, it might be just written . Note: Many engineers (I being one of them), and some clients too, thought the TMR system was “overkill.” particularly for peaking power plants. This is because the turbines were only rarely operated (emergency and peak demand situations) and that failures more frequently occurred with field sensors and wiring rather than with one of the three computers.
Fig. 16-2- Engineer testing a Speedtronic™ Mark IV panel with TMR System on right
Fig. 16-2 above depicts an engineer working at a factory test panel. Unlike the Mark I which was 36 inches wide, the Mark IV panel was 54 inches across with double (French) doors. This permitted better and safer access to the processors and other circuits inside the panel.
Note: If the Occupation Safety and Health Administration (OSHA) existed in the 1960s – 1970s, they would have likely closed down the production of GE‟s 36-inch panels as unsafe for electricians, technicians and turbine operators (in my opinion). There was insufficient room to work safely inside this “phone booth” of a control panel. Mark V became the Speedtronic™ control system of the 1990s. There was an operator interface system called on turbines at the beginning of the decade. It was a I-DOS based system and utilized a desktop PC to display operating conditions and significant data. Competitors of GE, particularly those in the upgrade business on GE turbines, were offering Microsoft Windows based interfaces, forcing GE to become more creative in their screen offerings. In early 2000, GE offered a human machine interface like the one shown in Fig. 16-3 below. This was a marked improvement over previous HMI. Also, GE offered an “historian” option to record data for further analysis.
Fig. 16-3- Speedtronic™ Mark V Control Panel The HMI concept offered more creativity in displaying data and graphics, including a facsimile of a turbine on the screen and data points corresponding to their physical locations on the unit (see green object in Fig. 16-3 depicting a gas turbine). The TMR system of Mark IV was continued in Mark V, again using 2/3 voting of three process controllers .
Fig. 16-4- Speedtronic™ Mark V panel (similar size enclosure to Mark IV)
Should the PC computer or its screen fail during turbine operation on the Mark V system, the control panel also was equipped with an auxiliary display where basic gas turbine operations can be monitored and controlled. Fig. 16-5 shows one such typical display for an early Mark V turbine. The turbine‟s most important operating data could be “called up” from the Backup Operator Interface and many of the basic functions ccould be initiated. Example: Raise/Lower Power Output (megawatts). A default screen shows the most important data: speed, FSR, Turbine Exhaust Temperature.
Fig. 16-5- Speedtronic™ Mark V Backup Operator Interface The screens in Fig. 16-6 show the difference between touch screen interfaces.
Fig. 16-6- Speedtronic™ Mark V Operation Touch Screen on Main Panel Around the turn of the century, GE offered the Speedtronic™ Mark VI system, which was continued in production to around 2008. Currently the Mark IVi is available (an “i” for internet variation), as a continuation of the Speedtronic™ trademark. Turbines with this system could be monitored back at GE‟s headquarters in Atlanta, GA. Note: Companies that offer alternatives to the GE Speedtronic™ systems were certainly driving forces to make General Electric “keep pace” with the available technology. Most of these companies, however, do not think it is necessary to offer TMR systems. One main processor, and hence a Simplex system, is all that is required; however, redundant sensors (like speed pickups, thermocouples, etc.) are appropriate.
Innovative Control Systems (ICS), HPI and Petrotech are competitors of GE in the controls alternative business. We have worked with all of them and have concluded that, in the turbine controls retrofit business, all of them offer reliable products in competition with General Electric. Tags: Control Sytems, HMI, Human Machine Interface, Integrated Temperature System, Mark II, Mark III, Mark IV, Mark V, Speedtronic™, TMR, Triple Modular Redundant
Peaking Power, Chapter Seventeen: The Long Anticipated 7EA! General Electric introduced the MS7001EA in the early 1990s to much fanfare, and deservedly so. From the introduction of the first so-called Frame 7B two decades earlier, the 7EA evolved and soon proved to be a workhorse machine of the power generating industry. It is rated about 90 MW at ISO conditions, a good size for base load, combined cycle, cogeneration and peaking applications in the USA. Most of the early Frame 7 problems were been “ironed out,” as the design has evolved from the first 7A unit installed at LILCO on Long Island, NY in 1970. The 7B & C proved to be popular for peaking and emergency applications delivering between 40 to 55 MW (depending upon model) through the seventies and early eighties. The 7E of the late 1980s was even better and more reliable at about 60 MW. With new technology (improved design, better metallurgy, ceramic coatings and air cooling of nozzles and buckets), the 7EA gas turbine soon became an industry darling.
Fig. 17-1- Isometric Colored Cross-sectional Rendering of MS7001EA The 7EA changed the philosophy of the General Electric‟s Package Power Plant (PPP). Many more auxiliaries were motor driven and installed on off-base skids: atomizing air, cooling water, water or steam injection, water washing, fire protection and, of course, liquid fuel forwarding. Part of the reason for off-base skids is the sizes of the auxiliary equipment. However, in most cases, it was deemed more efficient to drive auxiliaries with motors than with an accessory gear. Only those devices that were critical to turbine operation and protection were driven by the accessory gear. They include: main lube oil, liquid fuel pump and the hydraulic supply pump.
The two photos below depict outside installations for power plants owned and operated by Aquila (formerly Missouri Public Service). Aquila was recently purchased by Kansas City Power & Light. There are four gas turbine/generators at this site.
Fig. 17-2: Outdoor installation of MS7001C at Greenwood, MO (converted to dual fuel) At the site below, also now owned by Kansas City Power & Light, one GE 7E gas turbine rated at about 60 megawatts provides power to a local township.
Fig. 17-3: Outdoor installation of MS7001E at Pleasant Hill, MO (peaking applications) Below, in Fig. 17-4, a used 7EA gas turbine originally installed in California was later sold and installed at its current site in Kalamazoo, Michigan.
Fig. 17-4: Outdoor installation of 7EA gas turbine generator at Kalamazoo, MI (gas fuel only) The next two photos in Fig. 17-5 and 17-6, a 7EA rotor, split between the turbine and compressor sections, is resting on rotor stands outside a power plant in New Jersey.
Fig. 17-5: MS7001EA turbine rotor on temporary stands (from #2 bearing end)
Fig. 17-6: MS7001EA compressor rotor on temporary stands (from inlet end) The 7EA gas turbine has many internal design features that are different from earlier frame 7 models. Fig. 17-7 shows air-cooled, Z-lock 2nd-stage buckets (the GE name for turbine blades). The 1st stage buckets are also air-cooled, but without shroud tips adjacent to the casing shrouds. Note: The photo below was taken as the turbine rotor was being lowered into the turbine shell, so the tip clearances are greater than normal.
Fig. 17-7: Turbine section of modern unit with air-cooled, Z-lock buckets
Fig. 17-8: First-stage turbine buckets (end view) showing internal cooling holes The most obvious area where the 7EA gas turbine deviates from earlier models of Frame 7s is in the combustion zone. In the early designs, the introduction of steam into the flame zone of combustors was sufficient to reduce the emissions to acceptable levels. As the limits became more stringent, a new combustion design was required. The introduction of dry-low nitrous oxide (DLN) combustors was a significant design change for these turbines, brought on by the requirements of the Environmental Protection Agency (EPA) requirements to limit hazardous exhaust emissions like nitrous oxide and carbon monoxide.
Fig. 17-9: Combustion Section for 7EA Turbine, Gas fuel only
Fig. 17-10: End view of dual fuel combustion system with steam injection connection above Although the MS7001EA gas turbine has been manufactured by General Electric Company for over two decades, it remains the favorite of many owners because of its simplicity and similarities to its original design back in 1970. Unlike the MS7001FA, to be addressed in a future blog chapter, the 7EA is a 3-bearing design with the generator on the “hot end” of the turbine. The 7FA, on the contrary, took a major departure from the 7EA with its “cold end” drive concept. Tags: Combustion, Frame 7, Gas turbine generators, gas turbines, General Electric‟s Package Power Plant, MS7001EA, turbines
Peaking Power, Chapter Eighteen: Conversions, Modifications & Upgrades Offering improvements to existing models of GE gas turbines has been an ongoing practice since the package power plant (PPP) was first introduced in the early 1960s. The general reference for these improvements is called “Conversions, Modifications & Upgrades.” The abbreviation CMU will be used herein for this cumbersome term. Also, Field Modification Instruction (FMI) is a commonly used term by GE to refer to the instructions to institute a necessary field change. Lastly, a Technical Information Letter (TIL) is a bulletin sent out by GE to notify owners of a recommendation to a particular GE gas turbine model for an improvement. Thus, CMUs can be required, recommended or desired for improved operation. Mechanical CMU An example of a CMU involves compressor variable inlet guide vanes (VIGV). GE offers a high-flow inlet guide vane modification. This requires the disassembly of the front end of the compressor to get to the VIGV. Fig. 18-1 shows the inner bushings on an older MS7001B gas turbine. Four vanes were inserted in the curved inner blocks with inner bushings. The bushing blocks were properly located in the factory by dowels that are then “staked” at several spots with a center punch to retain them. The inner blocks were held in place by two hex-head bolts. Study the photo.
Fig. 18-1- Compressor Inlet Guide Vane modification to replace dowels of Inner Blocks The inner bushings on the lower half are difficult (nearly impossible) to remove unless the turbine rotor has also been removed. The three stake points on the dowels (See Fig. 18-1) must be ground away using a Dremmel tool, or equivalent. A screw can then be inserted in the dowel head and a special tool is required then to pry out the dowels. Working in tight quarters, then a low-profile socket with an Allen head is needed to unscrew carefully the two hex-head bolts. This can be done with patience, however, with the rotor in place. PAL Turbine Services, LLC 108
has developed the tooling and accomplished this technique, saving the client hundreds of thousands of dollars. In short, a major overhaul, including rotor removal, can be avoided.
Fig. 18-2- New T-Pin Dowels on inner IGV blocks GE offered a CMU that included machining of the rub ring that retains the new T-pin dowels shown in Fig. 18-2. Both halves of the rub ring need to be machined if all the dowels are being replaced; it is recommended that the two halves be bolted together to maintain “roundness” before the machining operation. This CMU has become very popular when the IGV need to be replaced or new bushings need to be installed. In some cases, when high-flow IGV are installed to replace the original ones for increased compressor efficiency, this CMU is employed. The T-Pin replacement is done in conjunction with machining of a stator rub ring creating a slot to retain the longer dowels. They don‟t need to be staked in place since the new machined slot will capture and secure them once it is “rolled” into place.
Fig. 18-3- T-pin Dowels with IGV Inner Blocks Installed in Lower Half The IVG upgrade advantages are shown in Fig. 18-4 and 18-5. This conversion has been employed by clients wanting more power output from their base-load turbines.
Fig. 18-4- Chart of IGV-Designs for Gas Turbines
Fig. 18-5- High-flow Inlet Guide Vanes
Inlet Guide Vanes are shown partially installed in a upper-half casing in Fig. 18-6 below. The pinion gears of some of the vanes are shown installed. The ring gear is shown engaging two of the gears.
Fig. 18-6- IGV Pinions and Rack Gear Frame 5N and 5P gas turbines, as well as 5-2B (two shaft units), have an assembly lip on compressor forward casing. This was a procedure utilized by GE as the compressor inlet casing (a.k.a. bellmouth) was set in a vertical position in the factory. This lip “acted” as a guide for lowering the forward compressor casing into place. GE suggested that this lip be removed (machined or ground off) to allow, in the future, for lifting the Upper Half (UH) bellmouth without disturbing the UH forward casing during IGV work.
Fig. 18-7- Compressor Forward Casing (IGV Gear Cover on Left)
The client has two choices as to how this could be accomplished: 1. Remove the forward compressor casing and send it to a machine shop to cut off the lip. 2. Without disturbing the forward casing, remove the outer lip of the upper half using a cutting wheel around the perimeter of the UH casing. The thin casing “half-moon” piece can then be easily lifted out. Thereafter, the UH bellmouth can be lifted out vertically. Controls CMU Controls CMU often involve removal of the original control system and replacing it with programmable logic controllers (PLC) similar to those described in Chapter 16 herein. However, most companies offering upgrades (GE included now) suggest a Simplex version and not the Triple Modular Redundant (TMR) systems described there in. For about ten years, GE has offered a “stripped down” version of Speedtronic™, including Mark IV, Mark V and now Mark VI. Competitors in the controls upgrade have offered a GE Fanuc™ or equivalent upgrade using the 90/70 version of a PLC. Because of their reduced cost, as compared to Speedtronic™, and more user-friendly features, they have become popular in competition with GE. The Simplex version was designed to fit into the same space as the original panel. See Fig. 18-8 and 18-9. The overall dimensions of the panels are Width: 36 inches, Depth: 36 inches, Height: 90 inches. The Mark IV panel in Fig. 18-10 has a built in CRT screen and soft switches for operator convenience. The approach to turbine control was a departure from most of GE‟s modern systems by using Simplex. Instead of three computers with 2/3 voting, the single controller approach with multiple sensors was taken by GE‟s competitors, keeping down the cost. GE first tried to sell the TMR approach but the cost drove clients into the camps of competitors. Competitors of GE brought in upgrades closer to $150,000. They included: Petrotech, Innovative Control Systems (ICS), HPI and even the dreaded Westinghouse, to name some of the major ones. GE pricing was nearly 3 times as high in many proposals seen.
Fig 18-9- Original Speedtronic™ Mark I Panel
Fig. 18-10- GE Speedtronic™ Mark IV Simplex “Drop in” Replacement Panel Early Speedtronic™ Mark V upgrades offered in the late 1990s offered a stand-alone Personal Computer (PC) for control and operation of the gas turbines. It was called an Interface and abbreviated .
Fig. 18-11- Early Mark V Simplex Screen (non-colored graphics) Due to competition, GE later offered a Speedtronic™ Mark V with a more colorful human machine interface commonly called an . The same upgrade was made available for clients who originally had the , as was the case at VIWAPA in the US Virgin Islands on their MS5001P that also got a high-tech internal parts upgrade.
Fig. 18-12- Mark V Simplex HMI Screen with color graphics The Microsoft Windows based affords various display screens for the operator. One such useful is to compare thermocouples versus combustion can locations. This allows comparison of temperature signals to determine if a fuel nozzle is clogged or has other problems exists.
Fig. 18-13- Example of Graphic Screen - Exhaust temperatures versus combustion cans The screens offer excellent possibilities for data analysis and recording.
Fig. 18-14- Temperature Data and settings Conversions, modifications and upgrades (CMU) offer opportunities for gas turbine owners and operators to make improvements to existing power plants. They know that replacing turbine/generators is a long and difficult process, taking years, approvals, zoning votes, permits and myriad political processes. CMU actions to the installed base of gas turbine power plants allows, in many cases, increases in power output and performance without resorting to new generation. In short, the older power plants are “grandfathered” and thus virtually unaffected by current regulations. For instance, the use of water or steam injection into the gas turbine combustors has two advantages: Reduction of dangerous exhaust emissions and an increase in power production. On the downside, the consumption of demineralized water is very high 115
(perhaps 1800 gallons per hour) and the impingement of the droplets on the cap of combustion liners erodes and eventually causes failures. Thus, some CMU have negative consequences. Tags: CMU, Field Modificaion Instruction, FMI, Human Machine Interface, Inlet Guide Vane, Interface, Mark V, Personal Computer, Speedtronic™, Technical Information Letter, TIL, TMR, Triple Modular Redundant, Variable IGV-Design Turbines
Peaking Power, Chapter Nineteen: Metals, Ceramic Coatings & Cooling Sometimes it is more prudent to invest in existing power plants to improve efficiency and power output than to retire and replace them with newer units. Improving gas turbine performance has much to do with raising turbine “firing” temperature to higher values. This has become possible by improving metals in the hot gas path, protecting turbine blades (buckets) shroud blocks and nozzle surfaces using ceramic coatings and improving the internal cooling capabilities of those same components.
Fig. 19-1- Turbine performance increase for higher firing temperatures
Study the graphs in Fig. 19-1. Turbine exhaust and firing temperatures are plotted on vertical axes; load (megawatts) and the command setpoint setting (VCE) are on the horizontal axis. Notice that the power output (load) increases as both the turbine firing temperatures increases. On colder ambient days, for instance @ 40˚F compressor inlet temperature, the air sucked into the compressor is denser, requiring more fuel to heat it an optimum turbine inlet temperature. As more fuel is burned, the result is a higher pressure, resulting in a greater amount of power (load) developed. That is, as a result of higher fuel consumption, the pressure at the trailing edge of the first-stage turbine nozzle increases providing a greater force on the turbine buckets (hence more power output). It may seem desirable to operate the turbine at even higher firing temperatures to maximize output, but limitations become metallurgical on the internal parts and turbine structure. The hot gas path (HGP) components are made from “exotic” metals allowing for higher temperatures. 117
These parts are internally cooled and their surfaces protected with thermal barrier coatings (TBC) to allow higher temperatures. Regarding the exhaust frame and stack parts, the generally accepted exhaust temperature limit is 1000 ˚F. The air used to cool the turbine parts is extracted from the turbine‟s own axial-flow compressor at various locations. Turbine bucket cooling, for instance, depends upon air extracted from the 17th stage. The extraction air first passes through the rotor distance piece. This high-pressure air, which is relatively cooler than the turbine wheels (at approximately 500 degrees F) passes through a cooling labyrinth and exits at the bucket tips. Look closely at Fig. 19-2. It shows three turbine stages for a MS6001B gas turbine. Notice the buckets in Stage #1 (left) with the bucket tip holes. Stage #2 (center) also has some internal cooling holes, but none is required on stage #3 (right).
Fig. 19-2- MS6001B turbine with bucket cooling holes in 1st & 2nd stages Fig. 19-3 below shows first-stage nozzle partitions with internal cooling holes. Air from the axial-flow compressor passes through these holes and out into the hot gas stream. The buckets show cooling holes in the tips. Thermal barrier coating (TBC) is shown on the first-stage nozzle partitions.
Fig. 19-3- Nozzle partition and turbine bucket holes and TBC on surfaces. Combustion liners often require TBC as shown in Fig. 19-4. The TBC protects the metal from high temperatures at the surface of the metal.
Fig. 19-4- Combustion Liner Coatings
In conclusion, raising the turbine “firing” temperature to the base load limit is acceptable, based on the design limits of the particular model gas turbine. However, as these designs have evolved, the metallurgical limits of the hot gas path components are often reached. Thermal barrier coatings (TBC) for the metals, as well as internal cooling using air from the gas turbine‟s own compressor, are required. Tags: axial-flow compressor, ceramic coatings, cooling, Exhaust, flame detection, gas turbines, HGP, hot gas path, metals, MS6001B, TBC, thermal barrier coatings, turbine buckets
Peaking Power, Chapter Twenty: F-Technology and Beyond General Electric began offering the MS7001FA around the turn of the 21st Century. The most obvious distinguishing feature of the 7F technology was the “cold-end-drive” design. The generator is connected to the compressor end of the turbine rotor, a departure from GE design concept for over 50 years. Also, unlike the MS7001EA design, the 7F turbine rotor spans only two bearings. These “F-Technology” units are ISO rated at approximately 150 MW. The greater power output rating was largely due to higher turbine firing temperatures. They are equipped with the latest “high tech” parts and components. For instance, the turbine section features single-crystal, firststage buckets that are internally cooled by air from the gas turbine‟s own axial-flow compressor, similar to the 7EA designs. Fig. 20-1 shows the end view of a first-stage turbine bucket for an Fmachine. Cooling holes and passageways are designed within the buckets. Notice that even the pressure side of the bucket has holes along the perimeter. Compressor inlet filtration is critical to keep the cooling air clean, so as to not clog these tiny cooling holes in the buckets, precipitating likely failures. Air flows through the inner passageways of the turbine bucket and out through the blade tips. The air inside is approximately 500F, while the outer surface of the bucket is at approximately 2400 F at base load.
Fig. 20-1- First-stage 7FA turbine buckets (air cooled) Fig. 20-2 shows interlocking, second-stage turbine buckets used on 7FA turbines. This stage is also cooled with air extracted from the turbine‟s own compressor. The temperature gradient allows the bucket material to cool and operate at higher surface temperatures. Buckets also have thermal barrier coatings (TBC) on the surfaces to protect the metal, as was explained in blog Chapter 19.
Fig. 20-2- Interlocking, air-cooled F-technology 2nd stage turbine buckets (shroud end view) The 7FA first-stage turbine nozzle segments are also air-cooled and very sophisticated in design. The nozzle partitions have cooling air holes both on the leading and trailing edge of the partitions. Also, the inner and outer sidewalls have cooling holes and show a TBC shown in white. See Fig. 20-3 and 20-4.
Fig. 20-3- First-stage air-cooled turbine nozzle segments showing internal cooling holes Air-cooled nozzle partitions are another way that gas turbines can accommodate higher firing temperatures, which increases power output and thermal efficiency. Cooling air is extracted from the axial-flow compressor presents a slight loss in overall efficiency but the benefit is there.
Fig. 20-4- First-stage turbine nozzle segments showing air-cooled partitions Turbine fuel nozzles have become far more sophisticated with the need for improved exhaust emissions and nitrous oxide (NOx) reduction in exhaust gases. See Fig. 20-5. Fuel nozzles of this design cost over $100,000 each, with a full set costing over one million dollars.
Fig. 20-5- Gas Turbine Fuel Nozzles for DLN-1 Operation Diaphragms are an integral part of the second-stage nozzle. They contain radial seals adjacent to the turbine rotor. Extraction air from the axial-flow compressor is blown into the seal area. The “angel wings” on each end seal the rotor near the roots of the turbine buckets.
Fig. 20-6- Nozzle Diaphragm with labyrinth (high-low) radial seals One might ask, therefore, what are the firing limits on gas turbines? It seems that certain “thresholds” are being approached and perhaps even touched upon with modern gas turbines. For simple-cycle (SC) applications, the limit for thermal efficiency seems to be about 40 percent. Single-crystal turbine buckets, internal cooling, ceramic coatings of some components are approaching limits. Combined-cycle (CC) applications appear to be “cresting” at 60 percent total plant thermal efficiency for gas and steam turbines in these configurations. Even if suppliers like GE, Siemens-Westinghouse and Mitsubishi Heavy Industries claim to have exceeded these levels, the operators doubt that operation will allow such diverse applications as plant cycling, daily starts and shutdowns or peaking power production. Operational flexibility may be more of a limiting factor than reaching or surpassing the mythical limits of 40 percent (SC) and 60 percent (CC). Looking to the future, the H-class turbines may be seeking other means of cooling. Under consideration is “steam cooling” to replace compressor extraction air from the axial-flow compressor in combined-cycle applications. However, the ability to monitor and control water “chemistry” will be a strong consideration in the quality of the steam being used. In conclusion, just when we think that gas turbines have reached their limits on firing temperature and efficiency, manufacturers seem to come up with other ideas for metals (buckets and nozzles), surface coatings and internal cooling methods. In other words, as we enter the second decade of the 21st century, I have only this advice: STAY TUNED!
Tags: Control Sytems, F-Technology, gas turbines, H-Class Turbines, inter-cooled
Peaking Power, Epilogue Starting from the University of Massachusetts in Amherst, MA in the fall of 1966 to today in my office in Upstate New York, my forty-plus years of involvement with gas turbines has made for a terrific career. Who could have known that General Electric field engineering work would take me to work in over twenty foreign countries? In Venezuela, I started as a field engineer and was later promoted to Area Engineer. I have thirty-one entry stamps for that country on my five cancelled passports. I served as acting Regional Manager for Venezuela, Colombia and the Caribbean on two different occasions. Since leaving GE, my returns to some of these same countries for my current company, PAL Turbine Services, LLC, has been a pleasure. It took a dramatic event to jump start GE‟s gas turbine business: the Northeast Blackout of November 1965. The next major event, a downturn for sure for the gas turbine industry, was the OPEC Oil Embargo of 1973-74. However, bracketed by these two events about a decade apart, there came significant advances in turbine technology with new products. The most significant was the advent of the MS7001 (also known as the Frame 7) and an electronic control system known as Speedtronic™. The Eighties brought co-generation and combined-cycle applications for the MS6001 gas turbine (Frame 6), along with digital control and protection systems pioneered with the GE‟s fourth generation of Speedtronic™ called Mark IV. The 1990s brought the beloved MS7001EA (Frame 7EA) and Mark V controls, a venture into computer-based technology with human machine interfaces (HMI). As the century turned, GE introduced the MS7001FA and Mark VI controls, as environmental and exhaust emission concerns forged front and center. So, five decades later, the gas turbine power plant remains a major player in the game and an integral part of the world power generation mix. Summary I worked for GE for nearly 20 years. I‟ve been “without the General” for over another two decades or so. One might say, it was a career in near perfect balance! As I look back to GE, after about one year working field jobs in 1968, GE trained me to be a gas turbine start-up engineer beginning in the summer of 1969. They applied for a military deferment since I was so “valuable” to them (their words). Even though I was in my late twenties, my draft number was a lowly 15 (for a birth date of April 11). As if by some degree of justice however, in January 1971, the company paid me back by sending me to Vietnam into the war zone to install two MS5001LA turbines. The site was about 10 miles north of Saigon on Highway One, going toward Tonsonut Air Force Base. The job in Vietnam lasted about five months. I had a crew of twelve women and four men. My crane operator was a woman. My welder was a woman. Even with some disadvantages (like an ongoing war), the plants were generating power in four months and the job was completed in May 1971. We certainly faced challenges in Vietnam. Here‟s one of my favorite stories: the mechanical TA on the job was named Willie Brandt. Willie was born a German, but lived in France from his early youth. He had served in the French Foreign Legion in Indochina in the late 1950s. Our chief mechanic on the job was a Chinese man named Lieu, who spoke both French and 125
Vietnamese. So here is a typical string conversation on the job: As lead technical director, I spoke English to the German engineer. The German spoke French to the Chinese foreman. The foreman spoke Vietnamese to the workers. The United Nations would be proud of us.
Fig. E-1- Standing on the walkway in front of control cab (circa 1971 in Vietnam) In 1983, I was fortunate enough to be selected as the Service Manager for the largest GE installation of gas turbines in the world. We installed fourteen GE STAG 109E power plants. The rating for the entire plant was over 2,000 megawatts. I was on the job for the first two years of a 5-year installation cycle. That was my last assignment with GE, as I left the company upon my return to the USA in 1985. After searching for “the meaning of life” for about a year, I started a company known as I&SE Associates of Schenectady, Inc. The name was a play on the familiar old GE service group: Installation and Service Engineering, just using the letters I&SE, for short. This often brought smiles to the faces of those who knew the GE service group in the “old days.” I&SE existed for about 12 years, where I specialized in training and troubleshooting services for clients who owned GE gas turbines installed in the 1960s a and 1970s era. My specialty was fuel regulator and early Speedtronic™ Mark I & II control protection systems. After a brief stint with another service company in the mid-1990s (no doubt one of my biggest mistakes), I started the current company in 1999 with Charlie Pond. The original name was Pond and Lucier, LLC, but in January 2009, I bought out Charlie and became the sole owner/operator of PAL Turbine Services, LLC. Charlie has remained working for PAL for as a senior consulting engineer.
I am still enjoying the career of field engineering after over four decades. Here I am below in Fig. E-2 checking out a Mark IV panel at PGE in Pittsfield, MA in 2001. Troubleshooting, training and consulting has kept me active in the career of field engineering. We field engineers are known as Turbine Cowboys in the industry.
Fig. E-2 Checking out a Mark IV Panel (circa 2001) I am pleased to say that a college degree from Umass-Amherst got me the job at General Electric. The twenty years that followed included FEP training, field assignments on gas turbines, factory test on steam turbines and teaching at GE‟s training center. The two companies I started kept me active in the power industry. Finally, as I am inclined to say: Knowledge + Experience = SAVVY. This was the magic formula for a successful career in gas turbine field engineering services. For all this and more, I am very grateful to General Electric for hiring me and later allowing me to transfer from the Technical Marketing Program to Field Engineering Services. Later in my career, I am thankful for an assignment in factory test in steam turbines and being hired to be an instructor at the FEDC. The latter job lead to promotion to the job of manager of the Field Engineering Program. My return to the field as manager of the TEPCO project in Japan for a couple of years was a great assignment. Finally, I have to thank GE for giving me the gumption to go out and start my own companies. I have often thought of the poem by Robert Frost that addresses how forks in the road are sometimes present with a choice about taking one path or the other along the trail of life. He talks about taking the one “I took the one less traveled by, and that has made all the
difference.” It certainly did for me. I find it fitting to end this Epilogue with Frost‟s entire poem. The Road Not Taken Two roads diverged in a yellow wood, And sorry I could not travel both And be one traveler, long I stood And looked down one as far as I could To where it bent in the undergrowth; Then took the other, as just as fair, And having perhaps the better claim Because it was grassy and wanted wear, Though as for that the passing there Had worn them really about the same, And both that morning equally lay In leaves no step had trodden black. Oh, I marked the first for another day! Yet knowing how way leads on to way I doubted if I should ever come back. I shall be telling this with a sigh Somewhere ages and ages hence: Two roads diverged in a wood, and I, I took the one less traveled by, And that has made all the difference. -Robert Frost