Vocational Training Report (BHEL)

Vocational Training Report "Water Turbine Manufacturing" By Sharad Jain Mechanical Engineering,3rd Year (0101ME111047)

1

Acknowledgement It gives me immense pleasure to present my Project Report before you. I thankfully acknowledge the HRD Department of BHEL, My Project Guide "Sir Giriraj Agarwal" for giving me so much co-operation and taught Each and Every Specification of Machines, Process, and Working Principles of Parts. I pay my sincere regards to him. Without his support I was not able to accomplish my training. I also thanks to all the working staff of WTMD Block, fabrication block for their helpful guidance and support during the entire period. I Also extend my Heartfelt gratitude to "Prof Aseem C. Tiwari (HOD, Mechanical Department) for giving me such an opportunity.

2

1

Certificate This is to certify that this project report has been made by "Sharad Jain" of UIT, RGPV , Mechanical Engineering, on "The Study of Water Turbine Manufacturing" under the guidance of "Sir Giriraj Agarwal". This Project has been completed successfully.

Yours truly, Sharad Jain Mechanical, 3rd Year UIT, RGPV Bhopal.

3

1

BHEL Overview BHEL is an integrated power plant equipment manufacturer and one of the largest engineering and manufacturing companies in India in terms of turnover. BHEL was established in 1964, ushering in the indigenous Heavy Electrical Equipment industry in India - a dream that has been more than realized with a well-recognized track record of performance. The company has been earning profits continuously since 1971-72 and paying dividends since 1976-77. BHEL is engaged in the design, engineering, manufacture, construction, testing, commissioning and servicing of a wide range of products and services for the core sectors of the economy, viz. Power, Transmission, Industry, Transportation (Railway), Renewable Energy, Oil & Gas and Defense. BHEL have 15 manufacturing divisions, two repair units, four regional offices, eight service centers and 15 regional centers and currently operate at more than 150 project sites across India and abroad. BHEL place strong emphasis on innovation and creative development of new technologies. The research and development (R&D) efforts are aimed not only at improving the performance and efficiency of our existing products, but also at using state-of-the-art technologies and processes to develop new products. This enables it to have a strong customer orientation, to be sensitive to their needs and respond quickly to the changes in the market. The high level of quality & reliability of our products is due to adherence to international standards by acquiring and adapting some of the best technologies from leading companies in the world including General Electric Company, Alstom SA, Siemens AG and Mitsubishi Heavy Industries Ltd., together with technologies developed in our own R&D centers. Most of Its manufacturing units and other entities have been accredited to Quality Management Systems (ISO 9001:2008), Environmental Management Systems (ISO 14001:2004) and Occupational Health & Safety Management Systems (OHSAS 18001:2007).

4

1

Water Turbines A hydraulic turbine is a prime mover (a machine which uses the raw energy of a substance and converts into mechanical energy) that uses the energy of flowing water and converts it into the mechanical energy (in the form of rotation of the runner). This mechanical energy is used in running an electric generator which is directly coupled to the shaft of the hydraulic turbine; from this electric generator, we get electric power which can be transmitted over long distances by means of transmission lines and transmission towers. The hydraulic turbines are also known as ‘water turbines’ since the fluid medium used in them is water.

CLASSIFICATION OF HYDRAULIC TURBINES The hydraulic turbines are classified as follows:

1. According type of energy at inlet of the turbine Impulse turbine & Reaction turbine 2. According to the direction of the flow of water Tangential flow turbine Radial flow turbine Axial flow turbine Mixed flow turbine 3. According to the head at the inlet of the turbine High head turbine Medium head turbine Low head turbine 4. According to the specific sped of the turbine Low specific speed turbine Medium specific speed turbine High specific turbine

If at the inlet of the turbine, the energy available is only kinetic energy, the turbine is known as impulse turbine. As the water flows over the vanes, the pressure is atmospheric from inlet to 5

1 outlet of the turbine. In the impulse turbine, all the potential (pressure) energy of water is converted into kinetic (velocity) energy in the nozzle before striking the turbine wheel buckets. Hence an impulse turbine requires high head and low discharge at the inlet. The water as it flows over the turbine blades will be at the atmospheric pressure. The impulse turbine may be radial flow or tangential flow type.

If at the inlet of the turbine, the water possesses kinetic energy as well as pressure energy, the turbine is known as reaction turbine. As the waters flows through the runner, the water is under pressure and the pressure energy goes on changing into kinetic energy. The runner is completely enclosed in an air tight casing and the runner and casing is completely full of water.

If the water flows along the tangent of the runner, the turbine is known as tangential flow turbine. If the water flows in the radial direction through the runner, the turbine is called radial flow turbine. If the water flows from outwards to inwards, radially the turbine is called inward radial flow turbine, on the other hand, if the water flows radially from inwards to outwards, the turbine is known as outward radial flow turbine.

If the water flows through the runner along the direction parallel to the axis of rotation of the runner, the turbine is called axial flow turbine. If the water flows through the runner in radial direction but leaves in the direction parallel to axis of rotation of the runner, the turbine is called mixed flow turbine. PELTON WHEEL OR IMPULSE TURBINES

The pelton wheel or pelton turbine is a tangential flow impulse turbine. The water strikes the bucket along the tangent of the runner. The energy available at the inlet of the turbine is only kinetic energy. The pressure at the inlet and outlet of the turbine is atmosphere. This turbine is used for high heads and is named after L.A. Pelton, an American Engineer.

CONSTRUCTION AND WORKING OF PELTON WHEEL TURBINE

A pelton wheel consists of a rotor, at the periphery of which is mounted equally spaced double hemispherical or double ellipsoidal buckets. Water is transferred from a high head source through penstock which is fitted with a nozzle, through which the water flows out as a high speed jet. A needle spear moving inside the nozzle controls the water flow through the nozzle and at the same time provides a smooth flow with negligible energy loss. All the available potential energy is thus converted into kinetic energy before the jet strikes the buckets of the runner. The pressure all 6

1 over the wheel is constant and equal to atmosphere, so that energy transfer occurs due to purely impulse action.

The pelton turbine is provided with a casing the function of which is to prevent the splashing of water and to discharge water to the tail race.

When the nozzle is completely closed by moving the spear in the forward direction the amount of water striking the runner is reduced to zero but the runner due to inertia continues revolving for a long time. In order to bring the runner to rest in a short time, a nozzle (brake) is provided which directs the jet of water on the back of buckets; this jet of water is called braking jet.

Speed of the turbine runner is kept constant by a governing mechanism that automatically regulates the quantity of water flowing through the runner in accordance with any variation of load. The jet emerging from the nozzle hits the splitter symmetrically and is equally distributed into the two halves of hemispherical bucket as shown. The bucket center line cannot be made exactly like a mathematical cusp, partly because of manufacturing difficulties and partly because the jet striking the cusp invariably carries particles of sand and other abrasive material which tend to wear it down.

Working Water at high pressure from the penstock pipe enters the nozzle provided with a spear. The pressure energy of water is converted into velocity energy, as it flows through the nozzle. By rotating the hand wheel, the spear is moved to control the quantity of water flowing out of the nozzle. When the spear is pushed forward into the nozzle, the amount of water striking the buckets is reduced.

The jet of water at high velocity from the nozzle strikes the buckets at the center of the cup. The impulsive force of the jet striking on the buckets causes the rotation of the wheel in the direction of the striking jet. Thus, pressure energy of the water is converted into mechanical energy. The pressure inside the casing is atmospheric. The pelton wheel operates under a high head of water. Therefore it requires less quantity of water. Draft tubes are not usually used with it.

REACTION TURBINES 7

1

If at the inlet of the turbine, the water possesses kinetic energy as well as pressure energy, the turbine is known as reaction turbine. As the waters flows through the runner, the water is under pressure and the pressure energy goes on changing into kinetic energy. The runner is completely enclosed in an air tight casing and the runner and casing is completely full of water. If the water flows along the tangent of the runner, the turbine is known as tangential flow turbine. If the water flows in the radial direction through the runner, the turbine is called radial flow turbine. If the water flows from outwards to inwards, radially the turbine is called inward radial flow turbine, on the other hand, if the water flows radially from inwards to outwards, the turbine is known as outward radial flow turbine. Casing: As mentioned above that in case of reaction turbine, casing and runner are always full of water. The water from the penstocks enters the casing which is of spiral shape in which area of cross section of the casing goes on decreasing gradually. It is made of spiral shape, so that the water may enter the runner at constant velocity through out the circumference of the runner. The casing is made of concrete, cast steel or plate steel.

Guide mechanism: It consists of a stationary circular wheel all round the runner of the turbine. The stationary guide vanes are fixed on the guide mechanism. The guide vanes allow the water to strike the vanes fixed on the runner without shock at inlet. Also by a suitable arrangement, the width between two adjacent vanes of guide mechanism can be altered so that the amount of water striking the runner can be varied.

Runner: It is a circular wheel on which a series of radial curved vanes are fixed. The surfaces of the vanes are made very smooth. The radial curved vanes are so shaped that the water enters and leaves the runner without shock. The runner is made of cast steel, cast iron or stainless steel. They are keyed to the shaft.

Draft tube: The pressure at the exit of the runner of a reaction turbine is generally less than atmospheric pressure. The water at exit cannot be directly discharged to the tail race. A tube or pipe of gradually increasing area is used for discharging water from the exit of the turbine to the tail race. This tube of increasing area is called draft tube.

Working First, water enters the guide blades, which guide the water to enter the moving blades. In the moving blades, part of the pressure energy is converted into kinetic energy, which causes rotation 8

1 of the runner. Water leaving the moving blades is at a low pressure. Thus, there is a pressure difference between the entrance and the exit of the moving blades.This difference in pressure is called reaction. Pressure acts on moving blades and causes the rotation of the wheel in the opposite direction.

FRANCIS TURBINE Francis turbine was developed by the American engineer Francis in 1850. It is an inward flow radial type reaction turbine. It operates under medium head.

Working Francis turbine consists of a spiral casing, fixed guide blades, runner, moving blades and draft tube.

The spiral casing encloses a number of stationary guide blades. The guide blades are fixed around the circumference of an inner ring of moving blades. Moving blades are fixed to the runner.

Water at high pressure from the penstock pipe enters the inlet in the spiral casing. It flows radially inwards to the outer periphery of the runner through the guide blades. From the outer periphery of the runner, water flows inwards through the moving blades and discharges at the center of the runner at a low pressure. During its flow over the moving blades, water imparts kinetic energy to the runner, causing the rotation of the runner.

Draft tube is a diverging conical tube fitted at the center of the runner. It enables the discharge of water at low pressure. The other end of the draft tube is immersed in the discharging side of the water called tail race.

Kaplan turbine is a low head reaction turbine, in which water flows axially. It was developed by German Engineer Kaplan in 1916.

All the parts of the Kaplan turbine (viz, spiral casing, guide wheel and guide blades) are similar to that of the Francis turbine, except the runner blades, runner and draft tube. The runner and runner blades of the Kaplan turbine resemble with the propeller of the ship. Hence, Kaplan turbine is also called as Propeller Turbine. 9

1

Working Water at high pressure enters the spiral casing through the inlet and flows over the guide blades. The water from the guide blades strokes the runner blades axially. Thus, the kinetic energy is imparted by water to the runner blades, causing the rotation of the runner. The runner has only 4 or 6 blades.The water discharges at the center of the runner in the axial direction into the draft tube. The draft tube is of L shape with its discharging end immersed into the tail race.

10

1

Plant Layout Of Block 1 Bay 1 Bar store On loading area Machine Shop (central) Component store

Bay 2 Machine Shop (East) Governor Machine Shop Tooling (Jig Fixtures) Governor Testing area

Bay 3 Machine Shop (East) Machine Shop (West) Testing Area

Bay 4 Machine Shop Machine Shop Assembly Area

CLASSIFICATION OF BLOCK 3 1.HMS (Heavy machining Shop) -In this shop heavy machine work is done with the help of different NC &CNC machines such as center lathes, vertical and horizontal boring &milling machines. Asia’s largest vertical boring machine is installed here and CNC horizontal boring milling machines from Skoda of Czechoslovakia. 2. Assembly Section (of hydro turbines) – In this section assembly of hydro turbines are done. Blades of turbine are1st assemble on the rotor & after it this rotor is transported to balancing tunnel where the balancing is done. After balancing the rotor, rotor &casings both internal & external are transported to the customer. Total assembly of turbine is done in the company which purchased it byB.H.E.L. 3. OSBT (over speed balancing tunnel)In this section, rotors of all type of turbines like LP(low pressure),HP(high pressure)& IP(Intermediate pressure) rotors of Steam turbine ,rotors of Gas & Hydro turbine are balanced .In a large tunnel, Vacuum of 2 torr is created with the help of pumps & after that rotor is placed on pedestal and rotted with speed of 2500-4500 rpm. After it in a computer control room the axis of rotation of rotor is seen with help of computer.

11

1

Manufacturing Process INTRODUCTION Manufacturing process is that part of the production process which is directly concerned with the change of form or dimensions of the part being produced. It does not include the transportation, handling or storage of parts, as they are not directly concerned with the changes into the form or dimensions of the part produced.Manufacturing is the backbone of any industrialized nation. Manufacturing and technical staff in industry must know the various manufacturing processes, materials being processed, tools and equipment's for manufacturing different components or products with optimal process plan using proper precautions and specified safety rules to avoid accidents. Beside above, all kinds of the future engineers must know the basic requirements of workshop activities in term of man, machine, material, methods, money and other infrastructure facilities needed to be positioned properly for optimal shop layouts or plant layout and other support services effectively adjusted or located in the industry or plant within a well planned manufacturing organization. Today’s competitive manufacturing era of high industrial development and research, is being called the age of mechanization, automation and computer integrated manufacturing. Due to new researches in the manufacturing field, the advancement has come to this extent that every different aspect of this technology has become a full-fledged fundamental and advanced study in itself. This has led to introduction of optimized design and manufacturing of new products. New developments in manufacturing areas are deciding to transfer more skill to the machines for considerably reduction of manual labor.

Manufacturing of Spherical And Butterfly Valves This kind of valve is generally used in the hydroelectric power plants as a turbine protection to guarantee the emergency shutoff of the pressurized water flow of the penstock. It’s placed immediately before the turbine and works automatically to shut off the water flow in case of any turbine malfunction, lack of power or any specified condition. The shutter is actuated by hydraulic cylinders moving it from the "ON" to "OFF" position by rotating of 90° on side trunnions. The valve in the open position has a fluid way which is essentially a straight cylinder so has approximately the same head losses as would occur in an equivalent length of pipe. Closure is effected by rotating the shutter 90° degrees, so it stops completely the fluid way. 12

1 To guarantee the fast closing in lack of power, suitable counterweights are installed on the shutter arm. Once shutter is closed, the perfect water tightness is guaranteed by Main Operation Seal: a downstream mobile sealing ring that closes against a fix rings seal on the shutter (both made of stainless steel with different grade of hardness). The other mobile ring is a Maintenance Seal: installed in the upstream side of the shutter, is used only in case of maintenance to the Main Operation downstream seal without the necessity to remove the valve form the site. Both of them are operated by the pressure of the water in the penstock trough a dedicated the water control system with piping. Seats NEVER touch the ball during opening or closing.

CLASSIFICATION OF MANUFACTURING PROCESSES For producing of products materials are needed. It is therefore important to know the characteristics of the available engineering materials. Raw materials used manufacturing of products, tools, machines and equipment's in factories or industries are for providing commercial castings, called ingots. Such ingots are then processed in rolling mills to obtain market form of material supply in form of bloom, billets, slabs and rods. These forms of material supply are further subjected to various manufacturing processes for getting usable metal products of different shapes and sizes in various manufacturing shops. All these processes used in manufacturing concern for changing the ingots into usable products may be classified into six major groups as Primary shaping processes Secondary machining processes Metal Forming processes Joining processes Surface finishing processes and

Processes effecting change in properties

PRIMARY SHAPING PROCESSES

Primary shaping processes are manufacturing of a product from an amorphous material. Some processes produces finish products or articles into its usual form whereas others do not, and require further working to finish component to the desired shape and size. The parts produced through these processes may or may not require to undergo further operations. Some of the

13

1 important primary shaping processes are:(1)Casting(2)Powder metallurgy(3)Plastic technology(4)Gas cutting(5)Bending and(6)Forging.

SECONDARY OR MACHINING PROCESSES As large number of components require further processing after the primary processes. These components are subjected to one or more number of machining operations in machine shops, to obtain the desired shape and dimensional accuracy on flatland cylindrical jobs. Thus, the jobs undergoing these operations are the roughly finished products received through primary shaping processes. The process of removing the undesired or unwanted material from the work-piece or job or component to produce a required shape using a cutting tool is known as machining. This can be done by a manual process or by using a machine called machine tool (traditional machines namely lathe, milling machine, drilling, shaper, planner, slotter). In many cases these operations are performed on rods, bars and flat surfaces in machine shops. These secondary processes are mainly required for achieving dimensional accuracy and a very high degree of surface finish. The secondary processes require the use of one or more machine tools, various single or multi-point cutting tools (cutters), jobholding devices, marking and measuring instruments, testing devices and gauges etc. forgetting desired dimensional control and required degree of surface finish on the work-pieces. The example of parts produced by machining processes includes hand tools machine tools instruments, automobile parts, nuts, bolts and gears etc. Lot of material is wasted as scrap in the secondary or machining process. Some of the common secondary or machining processes are: Turning Threading Knurling Milling Drilling Boring Planning Shaping Slotting Sawing 14

1

15

1

NON- DESTRUCTIVE TESTING Failure of the turbine blades was one of the challenges addressed with the help of BHEL by modifications of LP stage-5 blade, shroud modifications etc., and based on its success, the same technique was used for other plants to sort out inherent problems. Grid-induced Outages Grid disturbance induced outages were overcome by house load schemes and in one-month viz., May 1998, as many as 150 house load operations took place and units operated withstanding these transients. Healthiness of the control system and other equipment to withstand external grid transients was remarkable. The sharp corner in the root section of the blade causes the blade to crack. Failure of the turbine blades was one of the challenges addressed with the help of BHEL by modifications of HP stage-5 blade, shroud modifications etc., and based on its success, the same technique was used for other plants to sort out inherent problems. The material used was 12Cr-Mo martensitic steel, which is a very high temperature resistant material. The microstructure was observed was tempered martensitic structure. These turbine blades were collected from Madras Atomic Power Station (MAPS) for analysis. These blades were found to be failed. These blades were used for the present investigation of defects using ultrasonic phased array and X-ray radiography techniques. Turbine blades are known to fail due to tempered martensitic embrittlement, fatigue, fretting, high temperature creep age hardening, fir tree design, high residual stresses etc. Chemical compositions of the turbine blade:

Element Weight % Sulphur 0.019 to 0.03 Phosphorus 0.019 to 0.028 Carbon 0.20 to 0.24 Chromium 12.8 + 1.2 Manganese 0.45 to 0.54 Silicone 0.30 to 0.43 Nickel 0.40 to 0.52 Vanadium 0.05 Molybdenum 0.1 to 0.13 Iron Balance

16

1

SPECIFICATIONS OF MACHINES

Narrow Gap Welding Machine Narrow gap welding (also called narrow groove welding) was developed to weld thick sections more economically. This welding procedure uses joint preparations with small, included angles, typically in the range 2-20°, which require less weld metal and less welding time to fill. Narrow gap techniques have been applied when welding using submerged arc welding (SAW), gas shielded metal arc welding (MIG/MAG, GMAW) and tungsten inert gas welding (TIG, GTAW) processes. However, narrow gap welding does require specialized equipment, because of the limited accessibility to the root of the preparation.

Specification

:

Edge Preparation Depth Of Joint Wire Size Feed rate of Wire Maximum Horizontal Movement

: :

Max 350 mm 3 to 5 mm

: 1 to 4 mm/cm : 6m

Maximum Vertical Movement

: 6m

Mario Carnaghi ( Italy ) Vertical Boring Machine

CNC Control

Fanuc 32i

Table Diameter

98.4″

Maximum Swing

118.1″

Maximum Turning Height Table Payload

98.4″ 88,000 lbs

Table Speed Spindle Drive ATC Coolant

1.5 – 150 rpm 140 HP 12 Positions yes

Splashguard 17

1

Motofil (Portugal) Robotic Welding Hydraulic Control 6 Axis Control CNC Controlled Robotic Arm Wire feeder controller Copper coated MS Wire Argon + CO2 Gas Cylinder Step Down Transformer

Centre Lathe :(Biggest of all BHEL) · ·

Max diameter over bed Max diameter over saddle

· ·

Length between centers Max weight of work piece

·

Spindle bore

:3200mm :250mm :16m :100 T :96mm

Manufacturer: SAFOP · ·

Swing over carriage Centre distance

:3500mm :9000mm

· ·

Weight capacity Spindle power

:120 T :196KW

·

External chucking range

:250-2000mm

· ·

Hydrostat steady range Max spindle rpm

:200-1250mm :200

18

1

CNC Indicating stand : Manufacturer : Heinrich Georg, Germany Turning diameter Turning length

:5.3m :15m

Weight capacity

:160 T

CNC Vertical Borer : Manufacturer : M/S Pietro Carnaghi, Italy Machine model · Table diameter

:AP 80TM-6500 :6500mm

·

Max turning diameter

:8000mm

·

Min boring diameter

:660mm

· ·

Max height for turning and milling Table Speed

·

Table load capacity

· · ·

Milling spindle speed Spindle taper CNC system

:7000mm :0.2-50 rpm :200 T :3.4-3000 rpm at40KW :BT 50 :SINUMERIK 840D

CNC Facing Lathe : KH-200-CNC ·

Swing over bed

:2300mm

· ·

Swing over carriage Max distance between faced plate and carriage

:1800mm :2000mm

·

Max weight of job held in chuck

:6000kg

· ·

Face plate diameter Spindle speed

:1800mm :1.4-400rpm

·

Main spindle drive Step boring Machine :

· · ·

Max boring diameter Min boring diameter Table

:2500mm :625mm :4000mmx4000mm

·

Max weight of job

:100 T

Headstock travel

:4000mm

:95.5KW

Double Column Vertical Borer : · ·

Table diameter Max traverse of cross rail

:4000mm :4250mm 19

1 · Max weight of work piece LH Left hand Ram

:4200mm

RH Right Hand Ram ·

Max weight of job

:50 T

CNC Skoda Horizontal Borer : · ·

Spindle diameter Taper spindle

:200mm :BT 50

·

RAM size

·

RAM length

·

Spindle length

:2000mm

·

Headstock

:5000mm

·

Table

·

CNC system

·

Job

:450x450mm :1600mm

:4000x3500mm :SIMENS 850mm : I.P. Outer

Horizontal Borer : LSTG 8006 ·

Spindle diameter

:250mm

·

Height of machining bed

:600mm

· ·

Max boring depth with spindle Max extension of RAM

:2000mm :1600mm

·

Width of bed guide ways

:2500mm

·

Actual length of headstock with vertical lift

:2150mm

·

Actual length of column horizontal feed

:15000mm

·

Lowest position of spindle axis upon bed guide ways

:1475mm

·

Machine weight with electrical equipment's

:140 T

·

Height of machine

:10.3m

CNC Lathe : 1-120 Ravens burg ·

Main spindle bore

:150mm

·

Distance between centers

:12m

·

Turning diameter over bed cover

:1400mm

· ·

Turning diameter over carriage Work piece weight unsupported

:1100mm :4000kg

·

Work piece weight between centers

:20 T 20

1

Horizontal Boring Machine : 1-28 · ·

Diameter of spindle Working surface of table

·

Max travel of table

·

:150mm :2250x1250mm

Max vertical travel of headstock Horizontal Boring Machine :

:1200mm :2000mm

·

Boring spindle taper

:BT50

· ·

Boring spindle diameter Headstock vertical travel

:160mm :3000mm

·

Longitudinal RAM travel

·

Longitudinal spindle travel

·

Column cross travel

·

Rotary table travel

·

Table load

:700mm :1000mm :10m :3000mm :40 T

Horizontal Boring Machine : 1-11 · ·

Boring spindle internal taper material Boring spindle diameter

:200 :320mm

· · ·

Max spindle travel Vertical head travel Transverse column travel

:2500mm :6000mm :6000mm

·

Max longitudinal column travel

·

Machine wattage

Double Column Rotary Table Vertical Borer : · Max diameter of work piece accommodated

:800mm :90KW :10m/12.5m

·

Max height of work piece accommodated

:5m

·

Diameter of table

·

Max travel of vertical tool head RAM slides

·

Max travel of vertical tool head from Centre of table

·

Max weight of work piece :200T for N