Internship Report BYCO
INTERNSHIP REPORT BYCO PETROLEUM LIMITED
Submitted by: AZKA RIZWANA SIDDIQUI 3rd Year, 5th Term Chemical Engineering March, 2013
DAWOOD COLLEGE OF ENGINEERING AND TECHNOLOGY
ACKNOWLEDGEMENT With all my regards, I pay my thanks and acknowledgments to the management department of BYCO Petroleum Pakistan limited (BPPL). I sincerely thank Miss. Mehreen Bashir Nawaz, Manager HR for letting me intern in BYCO oil refining complex. I would also like to thank Engr. Abdul Qadir, as he supervised and advised us throughout the internship and utilizes his time on guiding and training us. I also would like to pay my thanks and respect to Engr. Salman Azeem and Engr. Asad ullah. I also like to acknowledge Engr. Azeem, Engr. Shams ur Rehman, Engr. Asad, Engr. M. Irfan, Engr. Hisham Hafeez, Engr, Aamir Iqbal and others for their support and time. This highly informative and interactive internship would have not been possible without the support of the Management of BPPL. I would like to mention my acknowledgments to all of the above respected peoples for giving me such an remarkable experience for my professional career. All my regards and respect to all of the above mentioned.
CONTENTS 1: INTRODUCTION TO BYCO PETROLEUM LIMITED:.............................................3 2: ENVIRONMENTAL HEALTH AND SAFETY:............................................................4 3: UTILITIES OF REFINERY:...........................................................................................4 3.1: WATER TREATMENT (REVERSE OSMOSIS PLANT):......................................5 3.2: BOILER:...................................................................................................................8 3.3: COOLING TOWER:..............................................................................................10 3.4: INSTRUMENT AIR:..............................................................................................10 4: INSTRUMENTATIONS, DEVICES AND SYSTEM:.................................................10 5: REFINERY:...................................................................................................................13 5.1: TYPES OF REFINERY:.........................................................................................13 6: CRUDE OIL:.................................................................................................................14 7: CRUDE DISTILLATION UNIT (CDU):......................................................................14 8: NAPHTHA HYDROTREATING:................................................................................17 9: GAS RECOVERY PLANT:..........................................................................................18 10: ISOMERIZATION UNIT:...........................................................................................20 11: REFINING PRODUCTS:............................................................................................22
1: INTRODUCTION TO BYCO PETROLEUM LIMITED: BYCO is one of the most reputable and highly regarded petroleum refining industries. BYCO Petroleum Pakistan Limited is relatively an emerging company in the industry. From oil refining, petroleum marketing and chemicals manufacturing to petroleum logistics, the group has diverse set of operations under it. BYCO Petroleum Pakistan Limited was incorporated in Pakistan as a public limited company in January 1995 and was granted the certificate of commencement of business in March 1995. BYCO Petroleum Pakistan's operational refinery has the capacity of 35,000 barrels at ORC-I and 120,000 barrels at ORC-II of crude oil per day to various petroleum products such as LPG, naphtha, motor gasoline, kerosene, jet fuel, HSD, furnace oil, HOBC. ORC-I (Oil Refining Complex-I) and ORC-II (Oil Refining Complex-II) takes ISO-9000, ISO 14000 and OSHA 18000 certification. ORC-I and ORC-II operate its own electricity, steam, and water treatment facilities.
INTERNSHIP REPORT 2: ENVIRONMENTAL HEALTH AND SAFETY: Environmental health and safety is a cross-disciplinary area concerned with protecting the safety, health and welfare of people engaged in work or employment. The goals of environmental health and safety programs include fostering a safe and healthy work environment. EHS may also protect co-workers, family members, employers, customers, and many others who might be affected by the workplace environment. EHS can be important for moral, legal, and financial reasons. All organizations have a duty of care to ensure that employees and any other person who may be affected by the companies undertaking remain safe at all times. Moral obligations would involve the protection of employee's lives and health. Legal reasons for ESH practices relate to the preventative, punitive and compensatory effects of laws that protect worker's safety and health. ESH can also reduce employee injury and illness related costs, including medical care, sick leave and disability benefit costs. Personal protective equipment (PPE) refers to protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury. The purpose of personal protective equipment is to reduce employee exposure to hazards when engineering and administrative controls are not feasible or effective to reduce these risks to acceptable levels. PPE is needed when there are hazards present. PPE includes safety shoes, safety helmets, apparels, gloves, goggles or glasses, ear muff or plugs and respirators. BYCO has got ISO-9000, ISO 14000 and OSHA 18000 certification, as its EHS departments are working responsibly to take every measures to protect environment.
3: UTILITIES OF REFINERY: The utility section in any industry is one of the most important departments as it provides all the basic needs to the industrial processes and operations. The function of utility section is to deliver the required help and services to run the plant and to yield the product. The utility section generally includes:
Water Steam Electricity Instrument air Manufactured gas Fuel Inert air
3.1: WATER TREATMENT (REVERSE OSMOSIS PLANT): Water treatment describes those industrial-scale processes used to make water more acceptable for a desired end-use. A lack of proper water treatment can lead to the reaction of solids and bacteria within pipe work and boiler housing. Steam boilers can suffer from scale or corrosion when left untreated leading to weak and dangerous machinery, scale deposits can mean additional fuel is required to heat the same level of water because of the drop in efficiency. Therefore water treatment is the most important facility as it reduces many hazardous factors related to the plant and industry. Reverse osmosis occurs when the water is moved across the membrane against the concentration gradient, from lower concentration to higher concentration. Reverse osmosis (RO) is a membrane-technology filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side. The treatment of water includes:
3.1.1: OPEN CHANNEL SYSTEM: The source of water for reverse osmosis plant is from Bore well and Hub dam spill back. The bore well TDS level is above 40,000 (approx. 54,000) and Hub dam spill back TDS Page 5
INTERNSHIP REPORT level is 35000 to 39000. The both sources of water are supplied to the plant through an open channel system.
3.1.2: CHEMICAL DOSING: Before treating the water, chemical dosing is done as to avoid the hazardous effects that can be happened due to the presence of some chemical impurities in water. 1. SODIUM HYPOCHLORITE: Sodium Hypochlorite 12% dose in the upstream of DAF after open channel feed pump in order to maintain a free chlorine level of 2.0 ppm to 3.0 ppm in the raw water tank to prevent the growth of bacteria in the system. Chlorine chemicals are very effective against bacteria, viruses and fungi that contaminate water. 2. CAUSTIC SODA: Caustic soda is also added to the water in order to maintain the pH of the water in between 8.2 to 8.5 to accomplish the function effectually. 3. FERRIC CHLORIDE: The impurities of water are also removed by the flocculation and coagulation. Ferric chloride is added to DAF in order to lift up the impurities forming cluster. These suspended clusters are then removed by scraping them off from the surface of water. 4. POLYELECTROLYTE: Polyelectrolyte aids ferric chloride to produce flocks. Polyelectrolyte is a polymer, which is when dissociate in water, charges the polymers to initiate the flocculation.
3.1.3: DISSOLVED AIR FLOTATION (DAF): Dissolved air flotation (DAF) is a water treatment process that clarifies water by the removal of suspended matter such as oil or solids. The removal is achieved by dissolving air in the water under pressure and then releasing the air at atmospheric pressure in a flotation tank. The released air forms tiny bubbles which adhere to the suspended matter causing the suspended matter to float to the surface of the water where it may then be removed by a skimming device. After chemical dosing, water is given a certain time to react with the chemicals. The water is then pumped to the DAF where all the suspended particles are scraped off from the top of the tank by blowing air in it. Some of the quantity of water is recycled back to DAF to attain maximum purity.
3.1.4: TURBIMAX FILTER: The water is then pumped to TURBIMAX filters. These filters are filled with sand and gravel. The water is entered from the top of the filter at a pressure of 100psi. All the impurities are captured by the sand and gravels, leaving rather purified water than DAF. Turbidity meter and chloride meter are installed in other to check the values during the operation. When there is a drop in pressure, the filters are then applied to backwash system to remove the caked impurities on sand and gravels. Page 6
INTERNSHIP REPORT 3.1.5: SEA WATER REVERSES OSMOSIS (SWRO): The water is then introduced into 5 micron cartridge filter at a pressure of 550-890 psi. Before introducing the water in SWRO filter, antiscalant and sodium metabisulfite is dosed to prevent the scaling on membrane and to remove chlorine. The pressure along the filter reduces the TDS from around 40,000ppm to 400ppm, where only 40% permeate is recovered while the 60% is rejected water. The latter is then flushed to the raw water tank and subjected to purify again.
3.1.6: BRACKISH WATER REVERSES OSMOSIS (BWRO): Likewise the water is then entered to BWRO 5 micron cartridge filter at a pressure around 150-200 psi. Caustic soda is dosed to maintain the pH of the BWRO water. The TDS of water is reduced from 400ppm to less than 10ppm, where 90% permeate is recovered. The 10% rejected water is flushed back to raw water tank to reprocess.
3.1.7: ELECTRODEIONIZATION: The water is then flowed to electrodeionization filter, where at 25 volts of current, the TDS of water is minimized to 0ppm, recovering 99% of permeate. The salts are split into its ions and moves towards their respective electrodes when current are applied, giving up 100% purified water. D.A.F Open channel
Permeate SWR O
INTERNSHIP REPORT 3.2: BOILER: A boiler is a closed vessel used to heat the water or other fluid for use in other operations and process. Generally boilers are used to generate steam for the usage of plants. There are two types of boiler, Fire Tube Boilers and Water Tube Boilers. When water is in the boiler drum and fire is in tubes to vaporize the water, the boiler is named as fire tube boiler. Likewise when the water is in tubes and fire is around the tubes in boiler drum, the boiler is said to be a water tube boiler.
3.2.1: DEMINERALIZED WATER: The demineralized water is used in boilers to convert water into steam, as demineralized water is free from all kind of impurities and minerals that at high temperatures and pressures can cause scaling and corrosion in the pipelines. From RO water plant demineralized water is pumped to boiler plant to produce high pressure steam.
3.2.2: HIGH PRESSURE DEAERATOR: Water is then pumped to high pressure deaerator to remove oxygen and other dissolved gases to avoid scaling and corrosion in pipelines. Hydrazine (N 2H4) is dosed into the deaerator to scavenge oxygen and moisture from water. Boiler feed water is showered from the top of deaerator and low pressure steam is introduced from the bottom, resulting in the rising of temperature of water up to 150°C. Here the chemical dosing scavenges the dissolved gases and moisture. All those gases leave the deaerator from vent and steam to the economizer.
INTERNSHIP REPORT 3.2.3: ECONOMIZER: Economizer is a mechanical device used to minimize energy consumption by reusing the left heat to preheat a fluid. In boilers, economizers are heat exchange devices that heat fluids, usually water, up to but not normally beyond the boiling point of that fluid. Economizers are so named because they can make use of the enthalpy in fluid streams that are hot, but not hot enough to be used in a boiler, thereby recovering more useful enthalpy and improving the boiler's efficiency. They are a device fitted to a boiler which saves energy by using the exhaust gases from the boiler to preheat the cold water used to fill it. High pressure boiler feed water pump pumped water to the economizer at 65 bar pressure at 140°C to the economizer. Here the flue gases at 350°C exchanges their heat to steam and leaving to the stack at 160°C. The temperature of steam is elevated to 190°C.
3.2.4: STEAM DRUM: A steam drum is a standard feature of a water-tube boiler. It is a reservoir of water/steam at the top end of the water tubes. The drum stores the steam generated in the water tubes and acts as a phase-separator for the steam/water mixture. The difference in densities between hot and cold water helps in the accumulation of the "hotter"-water/and saturated-steam into the steam-drum.
3.2.5: SUPER HEATER: A super heater is a device used to convert saturated steam or wet steam into dry steam used in steam engines or in processes, such as steam reforming. The steam from steam drum is then flowed to the super heater at a temperature of 250°C. In super heater the flue gases from the burners of steam drum, exchanges their heat to the steam resulting in the further rise in the temperature of steam to 340°C at 42 bar pressure. The steam generated by water tube boiler is high pressure steam, which is then utilized for the refining of crude oil and generating low pressure and moderate pressure steam as per required. S t a c k
Flue gases Super heater HP steam
INTERNSHIP REPORT 3.3: COOLING TOWER: Cooling tower is a device used to remove the heat from the fluid to the atmosphere. The principle phenomena of cooling tower are evaporation and condensation of fluid to the near wet bulb temperature by using sensible heat. Cooling tower is used to cool and humidify the hot process fluid to a certain low temperature. Water needing to be cooled is pumped to the top of the tower and then directed to flow down a designated path where the water forms into droplets. These droplets are met by a current of air that is blowing upward and past the water. The water is cooled by the air as it passes. It then collects at the bottom of the cooling tower structure where it is returned to the production process. Some air-cooled towers use large fans at the top of the structure to draw the air up. Cooling towers are used to reject heat through the natural process of evaporation. Warm recirculating water is sent to the cooling tower where a portion of the water is evaporated into the air passing through the tower. As the water evaporates, the air absorbs heat, which lowers the temperature of the remaining water. This process provides significant cooling to the remaining water stream that collects in the tower basin where it can be pumped back into the system to extract more process or building heat, thereby allowing much of the water to be used repeatedly to meet the cooling demand.
3.4: INSTRUMENT AIR: Instrument air, filtered with a range of 0 to 20psig, is used for plant pneumatic instruments such as steam flow meters, pressure controllers and valve positioners. The instrument air is also required to regulate automatically the opening of control valves in steam flow governors of steam driven turbines.
4: INSTRUMENTATIONS, DEVICES AND SYSTEM: An instrument is a device that measures a physical quantity such as flow, temperature, level, distance, angle, or pressure. Measurement instruments have two traditional classes of use:
Monitoring of processes and operations
Control of processes and operations
A number of instruments are used to run, monitor and manage the process. These are: Page 10
INTERNSHIP REPORT 4.1: PUMPS: Pump is a device that raises, transfers, delivers, or compresses fluids or that attenuates gases especially by suction or pressure or both.
4.1.1: CENTRIFUGAL PUMPS: A centrifugal pump consists of an impeller and an intake at its center. These are arranged so that when the impeller rotates, liquid is discharged by centrifugal force into a casing surrounding the impeller. The casing is there in order to gradually decrease the velocity of the fluid which leaves the impeller at a high velocity. This velocity is converted to pressure which is needed to discharge the fluid.
4.1.2: POSITIVE DISPLACEMENT PUMP: A positive displacement pump makes a fluid move by trapping a fixed amount and forcing and displacing that trapped volume into the discharge pipe.
4.2: COMPRESSOR: A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible; while some can be compressed, the main action of a pump is to pressurize and transport liquids.
4.3: VALVES: A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves may be operated manually, either by a handle, lever, pedal or wheel. Valves may also be automatic, driven by changes in pressure, temperature, or flow.
4.4: TRANSMITTERS: An electronic device that generates and amplifies a carrier wave, modulates it with a meaningful signal derived from speech or other sources, and radiates the resulting signal from an antenna. These transmitters are used to measure pressure difference, velocity, flow area, temperature and other major specifications to either monitor or control processes.
4.5: TURBINES: A turbine is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work.
INTERNSHIP REPORT 4.6: HEAT EXCHANGERS: A heat exchanger is a system that exchanges heats between two fluids without bringing them in direct contact, one fluid giving out the heat while other accepting the heat.
4.7: REBOILER: Reboilers are heat exchangers typically used to provide heat to the bottom of industrial distillation columns. They boil the liquid from the bottom of a distillation column to generate vapors which are returned to the column to drive the distillation separation.
4.8: FURNACE: An industrial furnace or direct fired heater is equipment used to provide heat for a process or can serve as reactor which provides heats of reaction. Fuel flows into the burner and is burnt with air provided from an air blower. The flames heat up the tubes, which in turn heat the fluid inside in the first part of the furnace known as the radiant section or firebox. In this chamber where combustion takes place, the heat is transferred mainly by radiation to tubes around the fire in the chamber. The heating fluid passes through the tubes and is thus heated to the desired temperature. The gases from the combustion are known as flue gas. After the flue gas leaves the firebox, most furnace designs include a convection section where more heat is recovered before venting to the atmosphere through the flue gas stack.
4.9: FAN: A mechanical fan is a machine used to create flow within a fluid, typically a gas such as air. The fan consists of a rotating arrangement of vanes or blades which act on the air. The rotating assembly of blades and hub is known as an impeller. Fans produce air flows with high volume and low pressure (although higher than ambient pressure), as opposed to compressors which produce high pressures at a comparatively low volume.
4.10: DRIER: A drier (dryer) is a process, in which moisture or water is removed from the fluid or other substances by the application of either some mechanical treatment or by some chemical treatment.
4.11: BLOWER: A blower is a machine for moving volumes of a gas (air) with moderate increase of pressure.
INTERNSHIP REPORT 4.12: CONDENSER: A condenser is a device or unit used to condense a substance from its gaseous to its liquid state, typically by cooling it. In so doing, the latent heat is given up by the substance, and will transfer to the condenser coolant.
5: REFINERY: An oil refinery or petroleum refinery is an industrial process plant where crude oil is processed and refined into more useful products such as petroleum naphtha, gasoline, diesel fuel, asphalt base, heating oil, kerosene, and liquefied petroleum gas.
5.1: TYPES OF REFINERY: 5.1.1: TOPPING: The topping refinery just separates the crude into its constituent petroleum products by distillation, known as Atmospheric Distillation. Topping Refinery produces naphtha but no gasoline.
5.1.2: HYDROSKIMMING: The hydro skimming refinery is equipped with Atmospheric Distillation, naphtha reforming and necessary treating processes. This type of refinery is more complex than a topping refinery and it produces gasoline.
5.1.3: CRACKING: The cracking or hydro cracking refinery, in addition to hydro skimming refinery, is equipped with vacuum distillation and catalytic cracking. The cracking refinery adds one more level of complexity to the hydro skimming refinery by reducing fuel oil by conversion to light distillates and middle distillates.
5.1.4: COKING: The coking refinery is equipped to process the vacuum residue into high value products using the Delayed Coking Process. The coking refinery adds further complexity to the cracking refinery by high conversion of fuel oil into distillates and petroleum coke.
5.1.5: INTEGRATED: The integrated refinery is equipped to upgrade its LPG or Naphtha into basic petrochemicals by way of aromatics production of Benzene, Cyclo Hexene, Meta Xylene, Ortho Xylene, Para Xylene and Toluene or Naphtha cracking.
INTERNSHIP REPORT 6: CRUDE OIL: Petroleum is a naturally occurring flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. The crude oils used in BYCO oil refining complex are UMM SHAIF and UPPER ZAKUM. The quality of crude oil mostly depends upon its viscosity and sulfur content. The higher the sulfur content, the sour the crude will be, likewise the lower the sulfur content, the sweet the crude will be. CHARACTERISTICS Specific gravity Sulfur wt%
UMM SHAIF 0.8408
UPPER ZAKUM 0.8546
7: CRUDE DISTILLATION UNIT (CDU): 7.1: DISTILLATION: Distillation is a method of separating mixtures based on differences in volatility of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction.
7.2: PROCESS FLOW: The distillation of crude oil generally includes a distillation column and a heated feed. In order to heat the feed up to a temperature where maximum yield can be obtained, feed is passed through multiple stages.
INTERNSHIP REPORT 7.2.1: FEED PREPARATION: The crude oil is pumped to the crude oil distillation plant, where it enters the preheating by heat exchanger with hot products raising temperature of feed up to 120°F. After passing by the heat exchangers, the crude is then entered to Desalter. In desater all salts are removed by conduction through electricity to avoid corrosion in stream lines. The crude oil is again directed to the train of heat exchangers and then furnace, thus the temperature of crude oil reaches 710°F. DESALTER: A desalter is a process unit on an oil refinery that removes salt from the crude oil. The salt is dissolved in the water in the crude oil, not in the crude oil itself . As the raw crude oil arriving contains quite a bit of water and salt, it is normally sent for salt removing first, in desalter. The crude is mixed with a water stream and intense mixing takes place over a static mixer. The desalter, a large liquid full vessel, uses an electric field to separate the crude from the water droplets. It operates best at 120 150 0C, hence it is conveniently placed somewhere in the middle of the preheat train.
7.2.2: DISTILLATION: From the furnace, the feed is then introduced into the atmospheric distillation column having 37 trays, at 30 psig and 710°F. Under these parameters, the crude is vaporized, releasing all the other components to their specific boiling point. To attain maximum refining, steam is injected from the bottom which strips out light materials from the heavier ones. There are two zones in a distillation column, rectifying zone and stripping zone. RECTIFYING ZONE: The rectifying zone is a name given to the section above the feed point, where the concentration of more volatile component increases in both the liquid and the vapor. STRIPPING ZONE: The stripping zone is a section below the feed point, where the concentration of volatile component decreases in both the liquid and the vapor. Five fractions are obtained from the distillation. These five are: NAPHTHA: Naphtha is carried out from the top of distillation column and is condensed and collected in the storage tank for further processing. KEROSENE: After naphtha, the first side stream withdrawn from the column is kerosene. Some of its fraction is stripped back to the column to remove the other lighter fractions. Kerosene is then cooled by exchanging its heat to the feed in preheater, processed and stored as a final product. LIGHT GAS OIL (LGO): The second side stream obtained is LGO, after some of its fraction is stripped back to remove lighter fractions. LGO is then cooled by exchanging Page 15
INTERNSHIP REPORT its heat to the feed in preheater. It is then pumped to the hydrotreater for sulfur removal and then stored as a product in storage tank. HEAVY GAS OIL (HGO): The third side stream of column is of HGO, some of which is also stripped back through strippers to remove the lighter fractions. HGO is also then directed to the preheater to exchange its heat to the feed and is then mixed with the reduced crude oil. REDUCED CRUDE OIL: The reduced crude oil is fractioned out from the bottom of the column and is cooled by preheaters and coolers. The reduced crude oil and HGO are mixed together and is then pumped to vacuum distillation column for further distillation under other conditions.
DISTILLATION COLUMN KEROS ENE PREH EATE FURNACE R
LGO PREH EATE R
PREH EATE R
PREH EATE R
PREH EATE R
PREH EATE R
REDUCED CRUDE OIL
INTERNSHIP REPORT 8: NAPHTHA HYDROTREATING: Hydro treating is a catalytic chemical process widely used to remove sulfur from natural gas and from refined petroleum products. The purpose of removing the sulfur is to reduce the sulfur dioxide (SO2) emissions that result from using those fuels. Another important reason for removing sulfur from the naphtha streams within a petroleum refinery is that sulfur, even in extremely low concentrations, poisons the noble metal catalysts (platinum and rhenium) in the catalytic reforming.
8.1: PROCESS FLOW: The hydro treating of naphtha includes the reaction of hydrogen with the poisonous inorganic compounds chained with naphtha. There are six reactions occur in hydro treatment of naphtha. These are: 1. 2. 3. 4. 5. 6.
Conversion of organic sulfur compounds into hydrogen sulfide Conversion of organic nitrogen compounds into ammonia Conversion of organic oxygen compounds into water Saturations of olefins Conversion of organic halides into hydrogen halides Removal of organic-metallic compounds
8.1.1: FEED PREPARATION: Naphtha from the overhead tanks of distillation column is mixed with hydrogen gas in a stream line. The mixture is then directed into the pre heater and then to the furnace, where the temperature of the mixture reaches in between 590°F to 600°F.
8.1.2: REACTOR: The heated feed is introduced into the catalyst bed reactor. The catalyst used in reactor is generally alumina base impregnated with cobalt and or a combination Page 17
INTERNSHIP REPORT of nickel and molybdenum. The mixture flows downward through the catalytic bed and hydrogen reacts with sulfur, nitrogen, oxygen, halides and other metallic components present in naphtha, forming hydrogen sulfides, ammonia, water, hydrogen halides etc. at that temperature, the olefins present in naphtha becomes saturated, leaving a rather purified form of feed for gas recovery plant.
8.1.3: SEPARATION: The product from the reactor is firstly cooled by heat exchange with fresh feed and then by air coolers and then flows into product separator, where liquid flows through the gas plant for splitting further while gases to the distillate hydrotreater. GASES
FEED SURGE DRUM
PREH EATE R
9: GAS RECOVERY PLANT: The purpose of gas recovery plant is to remove or separate lighter ends from the feed or naphtha. It is same as usual distillation, where feed is fractioned, recovering all the possible products.
9.1: PROCESS FLOW: The process consists of a sequence of fractioning columns, each with specific purposes of removing fractions from the naphtha.
9.1.1: NAPHTHA: Naphtha from the hydro treater plant enters the gas recovery plant to be fractioned further. Page 18
INTERNSHIP REPORT 9.1.2: DE-ETHANISER: The feed is then introduced in the de-ethaniser column containing 30 trays from the top at 190 psig and 350°F. When the feed enters the column, light hydrocarbons flashes off and rises up the column and is drawn off from there and cooled for using as a fuel in refinery furnace. The bottom containing the remaining fractions is then pumped to de-butaniser.
9.1.3: DE-BUTANISER: The bottom of de-ethaniser column is then flowed in to the de-butaniser having 24 trays, at 146 psig and 400°F. Feed enters from the top bottom of the column where propane and butane are vaporized to flow up the column and is cooled and condensed. The overhead product is firstly washed by gas absorption method by the solution of mono ethanol amine to remove hydrogen sulfide and other sulfur components. The mixture of propane and butane are then stored as a market product. 9.1.4: DE-ISOHEXANISER: The bottom of de-butaniser is introduced into de-isohexaniser containing 70 trays, at 50 psig and 350°F as the boiling points of i-hexane and n-hexane are very close (140°F and 156°F). Feed from the bottom is flashed into and pentanes and iso-hexanes are taken overhead, condensed and stored. Some of the part of the overhead is refluxed back to maintain the purity and parameters of the column.
D EE T H A NI S E R
D E B U T A N I S E R
A BS O RP TI O N C O L U M N
I-HEXANE D E I S O H E X A N I S E R
INTERNSHIP REPORT 10: ISOMERIZATION UNIT: 10.1: ISOMERIZATION: Isomerization, the chemical process by which a compound is transformed into any of its isomeric forms, i.e., forms with the same chemical composition but with different structure or configuration and, hence, generally with different physical and chemical properties.
10.2: PROCESS FLOW: Pentane from deisohexaniser is used as a feed for the isomerization unit. Water must be removed from feed as water is poison to catalyst. Reaction takes place in the excess of hydrogen which must also to be dried. Two reactors are used in series to convert maximum n-paraffin into i-paraffin. Unconverted n-paraffin is recycled back to Penex unit. Isomerization unit consists of three sections: Feed preparation, Penex and Molex
10.2.1: FEED PREPARATION: The light naphtha from the overhead of the gas plant de-isohexaniser column and hydrogen is introduced in feed preparation section of ISOM plant. Here the mixture of naphtha and hydrogen is filtered for the removal of particles and coalesce. The feed is heated to the required temperature for sulfur removal, usually up to 250°F and passed down flow over the adsorbent. It is then flows through sulfur guard bed. The purpose of sulfur guard bed is to protect the Penex catalyst from sulfur in the liquid feed. After sulfur removal, the mixture is dried and cooled to 100°F and send to the Penex section.
NAPHTHA AND HYDROGEN
PREH EATE R
PREH EATE R
FEED SURGE VESSEL
10.2.2: PENEX UNIT: The feed from the feed surge drum is pumped to pre heater. From the preheater the feedstock is directed into the first reactor where saturation of olefins occurs. The feed is then moved to the next reactor, where isomerization is occurred and n-paraffin is converted into i-paraffin by the help of catalytic bed in the reactor. Page 20
INTERNSHIP REPORT The hot stream is then passed through heat exchanger giving out its heat to the fresh feed and then is routed to the stabilizer column. The purpose of stabilizer is to separate any dissolved hydrogen, HCl and cracked gases from isomerate. The overhead vapor of stabilizer is cooled and stored in stabilizer receiver. The bottom product of stabilizer is routed to Molex unit by passing through coolers. The stabilizer off gas flows up gush through the stabilizer gas scrubber to remove hydrogen chloride by showering caustic from the top of the tower. GAS TO FUEL FEED SURGE VESSEL
LIGHT HYDROCARBONS S T A B I L I Z E R
HYDROGEN PREH EATE R
G A S S C R U B B E R
REACTOR 2 CUASTIC TO KERO WASH
10.2.3: MOLEX UNIT: The feed from the stabilizer is pumped to the rotary valve via filter for the preventative measures against the loss to the rotary valve. ROTARY VALVE: A rotary valve is a type of valve in which the rotation of a passage or passages in a transverse plug regulates the flow of liquid or gas through the attached pipes. At one time two streams is entering the chamber are the feed and desorbent. Extract and raffinate exit the chamber. A pump around stream continually circulates from the pump around pump to the top of the chamber, through the chamber and back to the pump. ADSORBENT CHAMBER: The adsorbent chamber has eight separate beds. The adsorbent material in the beds traps normal paraffins from the charge in its pores. Other hydrocarbons are not of a suitable shape to fit in the pores. Normal paraffins in the charge displace desorbent from the pores and the resulting raffinate goes back to the rotary valve and then to the raffinate mixing drums. The adsorbent in the bed is recharged by desorbent that the valve switches to the bed. The desorbent displaces normal paraffins due to a higher concentration of butane and resulting extract goes back to the rotary valve and then to the extract mixing drum. Liquid flow in the adsorbent chamber is always downwards. Page 21
FEED SURGE VESSEL ROTARY VALVE CHLORIDE GUARD BED
A D S O R B E N T C H A M B E R
E X T R A C T
R A F F I N A T E
C O L U M N
C O L U M N EXTRACT
EXTRACT: The extract contains the extracted n-paraffins and desorbent, leaves for the extract column. The extract line enters the extract column. The lighter desorbent components are taken overhead in the extract column receiver and are pumped to storage tank for reuse. The extract containing n-paraffins are recycled back to Penex unit for conversion into iso-paraffins. RAFFINATE: The raffinate, containing the higher octane non-normal paraffins and desorbent, leaves the chamber to the raffinate column. The raffinate column sends the lighter desorbents components overhead and drops the non-normals out the column bottom. The raffinate is cooled in the heat exchanger and stored in the tank.
11: REFINING PRODUCTS: The products obtained from the refining of the crude oil are: Furnace oil, Kerosene, Fuel oil, Diesel, Liquefied Petroleum Gas (LPG), Fuel gas, petrol and etc.
Fractions Gas/LPG Light naphtha Heavy naphtha Kerosene Gas oil Residue
CRUDE ANALYSIS UMM SHAIF Wt% Vol% 3.39 3.81 8.68 10.49 6.37 7.16 18.31 19.53 25.90 21.64 34.63 37.37 100.00 100.00
UPPER ZAKUM Wt% Vol% 4.42 5.61 7.6 9.48 5.05 5.84 14.67 15.97 21.88 22.00 46.38 41.10 100.00 100.00