A TRAINING REPORT ON
INDIAN OIL CORPORATION LTD. HALDIA REFINERY
DURATION - June 03, 2014
–
June 30, 2014.
PREPARED AND SUBMITTED BY:ANUPAM SRIVASTAV
DEPARTMENT OF CHEMICAL ENGINEERING BUNDELKHAND INSTITUTE OF ENGINEERING AND TECHNOLOGY, JHANSI -284128
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Contents Acknowledgement_________________________________03 Person to Whom Reported___________________________04 Preface__________________________________________05 Plant Overview ___________________________________05 Haldia Refinery Product____________________________07 Fuel Oil Block____________________________________09 DHDS Block_____________________________________18 Once Through Hydrocracker Unit Block ______________ 39 Lube Oil Block ___________________________________49 Oil Movement and Storage Block_____________________69 Conclusion ______________________________________71
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ACKNOWLEDGEMENTS We would like to express our heartfelt gratitude to the Training and Placement cell of Bundelkhand Institute of Engineering and Technology, Jhansi and Indian oil corporation Ltd, Haldia management for providing us with the opportunity to undertake our in plant Industrial Training in one of the most technically advanced and reputed refinery in India. We would like to personally thank: Mrs Mohua Basu, Mr Amal Bikas Das, Mr Sandeep Lahiri, Mr Shantanu Kumar Sarkar, Mr K.C.Mukherjee, Mr P.K. Mandal, Mr A. Mukherjee, Mr Lallan Kumar Paul, Mr D.P. Chakraborty And all the members of I.O.C.L. of Haldia refinery for making our training successfully. We would also like to thank all our respected and dear friends without whom guidance and help it would not have been possible for us to be successful in our training. Date: June 30, 2014. Place: I.O.C.L. Haldia.
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PERSONS TO WHOM REPORTED
Referred to : Shri. Shantanu Kumar Sarkar (CPNM):Shri S. Lahiri (CPNM):-
NAME OF AREA I/C
SIGNATURE OF AREA I/C
Fuel Oil Block: Shri A. Mukherjee(SPNM)/Shri S. Choudhury(PNM )
Diesel Hydro De Sulphurisation Unit: Shri P. Adhikary (PNM)/Shri P.K Mandal(DPNM) Once through Hydro Cracker Unit: Shri K.C Mukherjee (SPNM) Lube Oil Block: Shri L.K Paul (PNM) Oil Movement & Storage Block: Shri D.P. Chakraborty(PNM)
Signature A. B. Das SO (MS, T&D)
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PREFACE This report is based on the project dissertation in I.O.C.L. Haldia I.O.C.L is one of the most advanced plant in India for oil refining. I.O.C.L has been using American, Japanese & Russian technology. The raw material that is used in plant is also imported from Arabian countries, transported by ship. Haldia refinery was initially lube oil based refinery. Total production capacity of plant is 7.6 MMTPA. This report is organised with various types of pressure, temperature, flow & Level measuring instruments & also D.C.S & P.L.C. This report is in a sequence of unit overview process instruments, D.C.S & P.L.C. IOCL is the only Indian company, which is prestigious list of Fortune 500. IOCL stared its journey way back in 1959 Indian oil company Ltd. It became Indian Oil Corporation limited in 1964. There are 7 refining running under IOCL and another one is under commissioning at Paradip. The seven refineries are as follows: 1. 2. 3. 4. 5. 6. 7.
AOD, Digboi Guwahati Haldia Mathura Barauni Vadodara Panipat
Uniqueness of Haldia Refinery: 1. One of the India’s three lube oil refineries producing high grade lube base feed stocks. 2. Incorporating 70% indigenous equipments for the first time in India. 3. India’s only refinery producing Bright stock -a lube oil base stock for making lube oil which is used in heavy duty equipment. 4. First Indian refinery to receive ISO-9002 certificate.
PLANT OVERVIEW The refinery manufactures fuel products & HVI grade lube oil base stocks.
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The refinery has the following units:
FOB(Fuel oil block)
LOB(Lube oil block)
DHDS(Diesel hydro desulphurization unit)
OHCU(Once through hydrocracker unit)
OM & S(Oil movement and storage)
TPS(Thermal power station)
Workshop
Quality control and Laboratory
ETP(Effluent treatment plant)
MIS(Management information system)
Training centre
IMA(Indian oil management academy at Township)
FOB compromises of following units:-
1. 2. 3. 4.
Crude Distillation unit(CDU-1,CDU-2) NAHDT Catalytic reforming unit(CRU) Kerosene Hydro Desulphurization unit(KHDS)
LOB comprises of the following units:-
1. 2. 3. 4. 5. 6. 7. 8.
Vacuum Distillation Unit(VDU) Propane De Asphalting Unit(PDU) Furfural Extraction Unit(FEU) Solvent De Waxing Unit (SDU) Lube Hydro Finishing Unit(LHFU) Bitumen Treating Unit(BTU) Vis Breaker Unit((VBU) Micro Crystal Wax(MCW)
9. Nitro Methyl Pyrolidyne(NPM) DHDS comprises of following main units:1. 2. 3. 4.
Hydro generation unit DHDS Sulphur Recovery unit(SRU) Amine Regeneration Unit(ARU)
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5. RFCCU(Regeneration fluidised Catalytic Cracking Unit) 6. MSQL(Motor Spirit Quality Up gradation) OHCU comprises of following Unit:-
1. Hydro Cracker 2. Hydrogen Generation Unit 3. Nitrogen generation Unit OM &S is subdivided into following sections for operating convenience:-
1. 2. 3. 4. 5. 6. 7. 8.
Crude tanker unloading Crude tank farm LPG storage LPG bottling plant Tank wagon loading Tank truck loading Bitumen filling station drum and pack Solvent tank firm
HALDIA REFINERY PRODUCTS
1. 2. 3. 4. 5. 6. 7. 8.
Liquefied petroleum Gas(LPG) Straight run naphtha(SRN) Motor spirit(MS) Bitumen Superior Kerosene oil Aviation Turbine Fuel(ATF) Russian Turbine Fuel(RTF) Mineral Turpentine oil(MTO)
9. High speed diesel(HSD) 10. Jute Batching Oil (JBO) 11. Light Neutral Lube oil base stock (LN-LOBS) 12. Bright Neutral Lube oil base stock (BN-LOBS) 13. Fuel gas 14. Slack wax inters neutral (IN-SW) 15. Slack wax Bright neutral (BN-SW)
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16. Carbon block feed stock (CBFS) 17. IOC process oil
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FUEL OIL BLOCK CRUDE DISTILLATION UNIT
INTRODUCTION:The crude distillation unit at Haldia Refinery was designed for processing of 2.5 MMTPA of Agajhari crude with a processing rate of 7500 MT per day considering 8000 on stream hrs. per Annum. The unit was debottlenecked in Dec’84 to 2.75 MMTPA by minor modifications. After that trays and column internals replacement was undertaken in May’88 with the help of M/S EIL to suit the column to process 3.16 MMTPA. Subsequently a prefractionator column was installed in May’96. With the addition of the prefractionator the capacity of CDU has increased to 10500 MT/Day of upper Zakum or Arab mix crude which is equivalent to 3.5 MMTPA considering 8000 stream hours per year. Crude distillation (Unit No 11) includes
Pre fractionator section
Topping section
Naphtha Stabilizer
Naphtha Redistillation
Gas plant (Unit No 12) includes
De-ethaniser
Amine washing of LPG
Depropaniser
Amine Absorption & Regeneration unit (unit no.15)
Fuel Gas Amine Absorption system
Amine(DEA) Regeneration
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PRINCIPLE OF OPERATION
Crude oil is heated to 120 1300C in the first set of pre heat exchanger before feeding to the Desalter.Crude is desalted to the extent of 95% in the Desalter. Crude is there after heated to approximately 180-200 C in the second set of heat exchangers and pretopped in the Prefractionator column to get overhead gasoline from the top(IBP-140) and pretopped crude from the bottom of the column. Again crude is heated to 260-265 C in the third set of exchangers and 350-360 in the furnace. The crude oil is then fractionated in the atmospheric distillation column (11C01) to obtain the following streams. Refining of overhead (IBP-140C cut)
a) IBP-140 C cut is fractionated in stabilization column into two products.
Very low boiling hydrocarbon portion upto BUTANE/BUTENE is obtained from overhead and routed to gas plant.
C5-140 cut is obtained from bottom and routed to Naphtha Redistillation column. b) Gas plant stabilizer overhead product is first distilled in De-ethaniser for
separation of ethane. 12C01 overhead stream, rich in ethane, is sent to fuel gas system of refining. De-ethaniser bottom is Amine washed in column 12C02 for removal of H 2S and then routed to Merox(unit-13) for mercaptan removal. Crudes presently being processed contain low H 2S in LPG range and Amine washing is not required. Hence the column 12C02 is by-passed. c) Merox Treatment: LPG from Gas plant is caustic washed and then sent to LPG extractor (13C01) where it comes in counter current contact with Merox catalyst dispersed in caustic solution. Mercaptan free raffinate LPG, after caustic separation is sent to LPG storage. d) Propane production: A part of Merox treated LPG is fractionated in Depropaniser column of gas plant to produce PROPANE of around 8-10 MT/Day depending on its requirement at Propane deasphalting unit in Lube oil block. e) Spiliting of C5-140 C cut: In Naphtha Redistillation column C5-140 C portion is fractionated into C5-90 and 90 to 140 C cut, i.e light naphtha and heavy naphtha. f) Kerosene/ ATF/ MTO/ RTF g) Gas oil
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CATALYTIC REFORMING UNIT INTRODUCTION The operating manual describes all necessary procedures for the start-up, stable& safe operation and shut down of the CRU (Catalytic Reforming Unit). The unit was built by M/S Technip using a process licensed jointly by Indian Institute of Petroleum, India and Institute Francias du petrole, France for processing 196 TMT of Naphtha with a stream factor of 8200 hours. In August-Sept 2005 a major revamp was carried out, with process licensed by M/S Axens of France, to increase capacity, enhance product quality. In June-May 12 M & I was carried out with the complete replacement of catalyst with UOP platforming catalyst to meet Euro-IV requirements. This manual has been made in pretext of CRU’12 catalyst replacement. The purpose of the catalytic reforming unit is to improve octane number of hydro treated gasoline, producing a total reformate cut(min.RONC 97) with minimum guaranteed yield of 84.4 wt% (SOR) and 83.3 wt% at EOR with reformate of 0.60 kg/cm2 RVP and hydrogen rich gas. The unit capacity after 2005 revamp was 216 MT/Yr, with an on stream factor of 800 hours. In the revamp, the first old axial reactor has been removed and a new radial reactor has been put on service as third reactor. Also, the second old interheater has been removed and a new heater put on service as a first interheater.
BATTERY LIMIT AREA:
PROCESS DESCRIPTION:
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Preheat section: Naphtha distillate from storage tank is fed by pump to magnetic filter, where the metallic particles are removed. The foreign material present in the feed are separated out and fouling in the preheat exchanger is reduced. Then it is mixed with H2 , make up gas from reforming unit and recycle gas discharge by compressor and is heated to about 360 0c in a preheat exchanger(packinox Exchanger) In the shell side where it is heated by hot reactor effluent.
Furnance and Reaction Sections Completely vaporised naphtha and gases, after passing through the first furnance is heated to the reaction temperature , enter at the top of the first down flow peactor. Operating pressure = 27.3 kg/cm2g Operating temperature =5120 C The reactor is filled with a bimettalic platinum –rhenium catalyst support on very high purity alumina. When the feed come in contact with catalyst reforming reaction take place .due to endothermicity of reaction, the temperature of reactant decreases. The effluent from the first reactor is therefore, reheated in a second furnance to make up the loss of heat in the first reactor. Operating condition for the second reactor: Operating pressure =26.3kg/cm2 Operating temperature = 512 0C Reheated effluent is then passed through the second reactor containing platinum – rhenium catalyst where further reforming reactions take place.Effluent from the second reactor is again reheated in furnace and passed through reactor containing the catalyst to complete the reforming reactions for obtaining the product with desired octane number.
Reactor effluent cooling system The effluent from reactor is cooled and partially condensed in a series of exchangers as follows. In the tube side of exchanger to preheat feed and to reboil stripper bottoms
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In the packinnox exchanger to preheat feed In shell side of the water cooler
The effluent thereafter is sent to the separator drum.
Separator Drum and recycled Gas section The reactor effluent is split into gaseous and liquid phases in separator drum.
The liquid phase is sent to stripper column Apart of gaseous phase is recycled as recycle gas within CRU Another part is sent to make up to Naptha Pretreatment section
Remaining to KHDS section The hydrogen rich gas from the separator drum is recycled by means of the centrifugal compressor. Part of the compressed gas is mixed with the preheated naptha as described earlier.
Stabilizer section The liquid from the separator drum is fed to the stabilizer . The liquid is reheated in the shell side of the exchangers with the stabilizer bottom product on the tube side and the enters the stablizer . A part of the stabilizer bottom product is reboiled in thermosyphon type exchanger. The stabilizer overhead vapours are cooled and partially condensed by condenser and are collected in the overhead horizontal reflux drum. The stabilizer bottom part is passed through exchangers and cooler before it is sent to storage and feed to reformer splitter. The top product from the stabilizer is sent to reflux drum where the gas stream is separated from the top of the drum and sent to fuel gas or M.S.Q.U unit . Apart of the liquid is pumped back into the stripper while the other consist of LPG to rundown.
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KERO HYDRO DE SULPHURISATION UNIT (KHDS) INTRODUCTION:
This describes all the necessary procedures for the start-up, operation and shut down of 577,500 TPA Kerosene Hydro Desulphurisation Unit. Installation of mounted APH with FD fans and replacement of existing natural draft burners with forced draft low NOx and low excess air burners in KHDS furnace has not only increased the overall efficiency of the furnace but also net savings in terms of capital cost by removing FO consumption in the furnace. This unit was built by TECHNIP and it uses a process licence jointly developed by Indian Institute of Petroleum and Institute Francis Du Petrole, France.
UNIT CAPACITY: The Kero Hydro De Sulphurisation unit is designed for 577,500 tons per year capacity with 8200 on stream hours.
PROCESS DESCRIPTION: FEED AND GAS PRE HEATING SECTION Raw Kerosene/MTO/ATF feed from the storage is taken to the unit through 23 FCV 01 by a pump 23 P OI A/B. The feed is subsequently mixed with recycle gas available from discharge of the compressor 23 K 01 A/B/K-101A which is taken as make up hydrogen to its suction ex CRU/DHDS. Both, liquid feed and gas streams are heated in heat exchangers 23 E 02 D C B A in the shell side while the hot reactor effluent passes through the tube side.
Hot mixture of liquid and gas from 23 E 02 D C B A is taken to the furnace 23 F 01. FURNACE AND REACTOR SECTION Pre heated Kerosene/MTO/ATF/RTF and recycle gas mixture is brought to the reaction temperature in the furnace 23 F 01. The furnace is installed with a top mounted APH with FD fans 23FD01 A/B were replaced with natural draft burners forced draft low NOx and low excess air burners. The modification in furnace was done in the view of savings in FO
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consumption. This Furnace is provided with two passes both in the radiation and convection sections. Symmetrical arrangement of inlet, outlet and coils of the furnace helps in equivalent distribution of the stream in both the passes. Nevertheless, two hand valves on the pass entrance can be used to regulate the flow distribution by matching the outlet process temperatures and skin point temperatures. EFFLUENT COOLING SECTION
The effluent from the reactor is cooled and partially condensed in a series of heat exchangers as follows:
In the tube side of 23 E 01, the recovered heat is utilised to reboil the stripper column 23-C-01 bottom material. In the tube side of 23 E 02 A B C D the recovered heat is utilised to preheat the feed and hydrogen. In the shell side of cooler 23 E 03 A B, the waterbeing the coolant. Finally the effluent is sent to the separator drum 23 B 01. SEPARATOR DRUM, MAKE UP AND RECYCLE GASES SECTION
The reactor effluent splits into 2 phases in the separator drum 23 B 01:
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The liquid phase is sent to the stripper column 23 C 01 through bottom level control valve. Top vapour is partially recycled by compressor 23 K01 A/B, K101 and rest is sent to lube oil Hydro finishing Unit/ Vaporizer through 23B01 pressure control valve. The liquid level in the separator drum is controlled by a regulator 23 LC 05. In addition, it is provided with a high level alarm and compressor cut off device, 23 LAHCO 04, to prevent any liquid flow to recycle compressor. At the top of the separator, a wire mesh sieve is provided to stop liquid entrainment along with gases. The pressure in the high pressure section is controlled by a controller which allows the excess vapour phase to hydro finishing unit.
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The separator drum is connected to an ejector to create vacuum in the unit during start-up& shut down. The recycle gas along with the makeup gas is compressed by parallel reciprocating compressors. The make-up hydrogen gas from CRU/DHDS comes to the suction of recycle gas compressors through a knock out pot. STRIPPING SECTION
The liquid from the separator drum is pre heated in the exchangers 23 E 04 A/B and fed into the stripper column 23 C 01. This stream passes through the lube side and recovers heat from the treated product through the shell side. The column consists of:
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17 ballast trays, type “two pass” below the feed point and 8 ballast trays, type “single pass” above the feed point.
A part of the stripper bottom is reboiled in the heat exchangers 23 E 01 on the shell side recovering heat from the reactor. RECOMPRESSING SECTION
The gas from the reflux drum, 23 B 02 goes via 23 B 02A to first stage of the three parallel reciprocating compressors. A high level alarm is provided in 23 B 02A. In case 23 K 02 A/B in line: The first stage discharge gas upon cooling in the water cooler is mixed with the gaseous stream ex LOB/U-11 PF column/U-16 PF column before sending to the knock out drum 23 B 04. Off gas stream of U-37(LOB) can be diverted directly to 15CO2 bypassing U-23 using the jump over at battery limit. The condensed hydrocarbons from the drum are sent to stripper column regulated by the high level controller 23 LC 14. This drum is provided with the high level alarm 23 LAH 13. The vapour from the knock out drum are compressed in the second stage of the compressors cooled in a water cooler 23 E 08 sent to the knock out drum 23 B 05. The vapours
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separated from the liquid hydrocarbon are sent to the fuel gas or amine unit. CHEMICAL INJECTION
CORROSION INHIBITOR DOSING OF ADDITIVES IN ATF RUN.
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DHDS BLOCK DHDS block comprises of following main units:1. 2. 3. 4.
DHDS RFCCU ARU SRU
5. MSQU
DIESEL HYDRO DESULPHURISATION UNIT Purpose:
To reduce the sulfur content of the sour diesel and to produce sweet diesel with sulfur content of less than 0.25/0.05 % by wt. Sulfur removal:
Feed stocks to the union fining .Unit contain simple mercaptanes, sulfides anddisulfides are easily converted to H2S. Feed stocks containing hetero atomic,aromatic molecules are preceded by initial ring opening and then sulfur removalfollowed by saturation of the resulting olefins. Nitrogen removal:
De-nitrogenation is generally more difficult than desulphurization. The de-nitrogenation of pyridine proceeds by aromatic ring saturation hydrogynolysis andfinally de-nitrogenation. Oxygen removal:
Organically combined oxygen is removed by hydrogenation of the carbon hydroxyl bond forming water and the corresponding hydrocarbon .Olefin saturation: Olefin saturation reaction proceeds vary rapidly and have high heat of reaction. Aromatic saturation:
Aromatic saturation reaction is the most difficult and exothermic.
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Metal Removal:
Metals are retained on the catalyst surface by a combination of adsorption and chemical reaction. Removal of metal normally occurs from the top of the catalyst bed and the catalyst has a certain maximum tolerance for retaining metals. Metal contained in the crude oil are usually nickel and vanadium. Iron is found concentrated at the top of the catalyst bed as iron sulfide, which is corrosive. Na, Ca and Mg are present due to the contact of the bed with salted water or additives. Improper use of additives, to protect the fractionator overhead systems from corrosion or to control foaming, accounts for the presence of P and Si. Lead may also deposit on the hydro treating catalyst bed from reprocessing leaded Gasoline through the crude unit. The total metal retention capacity of the catalyst system can be increased by using a guard reactor or guard bed of catalyst specially designed for demetallisation. Halide removal:
Organic halides such as chlorides and bromides are decomposed in the reactor.The inorganic ammonium halides sides, which are produced when the reactoreffluent is cooled, are dissolved binjecting water into the reactor effluent or removed with a stripper off gas.
Process Description: The DHDS unit is based on the diesel union fining process of UOP and iscomprised of four main section The feed section Reactor circuit section Separator or compressor section Fraction section
Feed Section
The feed stocks consisting of mainly straight run gas oils and lightcycle oil from FCCU from Storage first passes through feed filters and feedexchangers heated by stripper bottom’s material before entering a
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combinedfeed coalescer and surge drum. The feed surge drum provides surge volume to even out the fluctuationsin the feed entering the unit .This surge volume allows the feed to the unit tobe kept as constant as possible which maximize the catalyst life length. Feedfrom the feed surge drum enters the feed pumps where its pressure is raised to allow the feed to enter the reactor circuit. Feed from the feed pump is combined with the recycle gas flow .Combined feed passes through cold and hot combined heat exchangers where it is heated by reactor effluent material .Then the feed is sent to the charge heater where it enters the reactor circuit sector section. Reactor circuit section
Combined feed from the feed section is heated to reaction temperature in the charge heater. Then the feed and recycle gas are proceeded in reactor 1and 2 which contain catalyst chosen for its ability to absorb metal in the field and to provide the proper level of desulphurization required to meet a specified diesel product property. The reactor 1 has two beds with one intermediate quench point.Quench is required due to the heat of the reaction and the need to limit the temperature rise to maintain the proper catalyst cycle length for the chosen space velocity The reactor 2 is a single bed reactor. To monitor the operation of the reactors bed, thermocouples are providing at regular intervals. Reactor effluent material is cooled in the hot combined feed exchanger .Water is injected into this stream before it enter the separator condenser. After cooling to the appropriate temperature, this is separated in the separator into vapor and liquid hydrocarbons phases to decant the sour water phase. The vapor from the separator is cooled in recycle gas cooler before entering the scrubber KO drum. The purpose of the recycle gas exchanger is to decrease the due point of the recycle gas so as to greatly lessen the possibility of condensing hydrocarbons material in the recycle gas scrubber, such HCs condensation contributes to the foaming of the amine.
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Process Flow Diagram:
REGENERATION FLUIDISED CATALYTIC CRACKING UNIT Introduction:
Indian Oil corporation limited (IOCL), Haldia Refinery has set up a 700,000 metric tons per annum capacity Fluid catalytic cracking unit(FCCU) at Haldia,West Bengal. The new plant mainly consist of reactors, regenerators, main fractionators, product recovery section including amine treating facilities Cracking reaction cracks down the long chain higher molecular weight hydrocarbon into the lighter molecular weight hydrocarbon .In course of cracking reaction, coke is also produced which remains on the catalyst particles and rapidly reduces its surface activity. In order to maintain the catalyst activity at a useful level, it is necessary to regenerate the catalyst by burning off the
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deposited coke.To achieve this , the catalyst continuously flows from reactor to regenerator, where coke is burnt off in the presence of oxygen.
Cracking Processes:
Cracking is a phenomenon by which large oil molecules are decomposed into lower boiling molecules. At the same time certain of these molecules, which are reactive, combine with one another to give even larger molecules than those present in the srcinal stock.In modern refining industries there are three basic processes for the conversion of heavy oil into useful products namely thermal cracking, fluidised catalytic cracking and hydrocracking. Process Description
Process Chemistry Theory:
Cracking process uses high temperature to convert heavy hydrocarbons into more valuable lighter products. This can be done either by thermal cracking or catalytic cracking. Catalytic cracking process has almost superimposed thermal cracking because of inherent advantage of low temperature and pressure. Catalytic cracking produces higher octane gasoline, a more valuable cracked gas and less of undesirable heavy residual products. Theory of catalytic cracking is based on carbonium ion formation and subsequent hydrogen transfer reaction.
Brief Process Description:
Fluidised cracking unit consists of the following sections: 1. 2. 3. 4. 5.
Feed preheat section Reactor/Regenerator section Flue gas section Catalyst Handling section Main fractionators section
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6. Product recovery section 7. Amine treating section Feed Preheat SectionCold feed from FCCU feed tank and hot feed from process units are combined and received feed surge drum, cold feed enters feed surge drum on level control and hot feed enters surge drum on flow control. A water boot on the drum allows for manual draining of any water, which may accumulate during start up upset conditions.The feed drum pressure floats on the main fractionator by means of a balanceline which ties into the fractionators below the LCO draw chimney tray.
AMINE REGENERATION UNIT Introduction:
Indian Oil Corporation Ltd. (IOCL) Haldia Refinery has Diesel Hydro De Sulphurisation Unit (DHDS) for meeting the H 2S removal application for 2000 AD. To meet the requirement a new Amine Regeneration Unit (ARU 26) is installed. The function of the unit is to supply lean amine to and regenerate rich amine from various users located in the DHDS unit. The ARU consists of 4 sections the rich amine section, the amine regeneration section, the lean amine section and the amine storage section. The acid gas from the ARU overhead is routed to the SRU and the lean amine to the DHDS unit Rich amine from Catalytic DE waxing unit shall be routed to ARU to meet this enhanced load minor revamp is done. Design Basis: Unit Capacity:
Design Capacity- The design capacity of the ARU is 118526 kg/hr. Increased load due to CDWU is 20176 kg/hr.
Turn down Capacity- The turndown capacity of the ARU is 50%. On Stream Factor- The on stream factor per year is 8000 hours.
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Product
Temperature OC Pressure
kg/cm2g
Lean Amine to DHDS
Acid Gas
43.3
40
12.5
1.0
PROCESS DESCRIPTION: Battery Limit Conditions-
Feedstock
Rich Amine Ex DHDS
Temperature OC
50.4
Pressure Kg/cm2g
2.04
Feed Characteristics:-
Rich Amine ex DHDS unit and CDW unit (Kmol/hr)
DHDS Unit
H2O DEA H2S H0.175 2 CH0.029 4 C7H 0.044 6 C3H 0.009 8 C4H 0015 10 C4
Total */
4837.20 276.37 90.210 ---0.005 0.064 0.011 0.025 0019
5203.96
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CDW Unit
806.20 46.03 14.79
0.004
876.05
Brief Process Description:
For simplicity, only the chemistry involved in H2S removal is discussed. Hydrogen Sulphide, H2S or HSH, is a weak acid and ionizes in water to form Hydrogen ions and sulphide ions: H2S + H2O→ H3O+ + HSSince it is a fairly weak acid, only a fraction of the H2S will ionize. Similar ionization will occur for the other acidic compounds present. Di-EthanolAmine (DEA) is a secondary amine. The overall reaction occurring in the DEA process can be represented by the following equation: (HOCH2CH2)2NH+H2S → (HOCH2CH2)2NH2++HS-. Detailed Process Description
Rich Amine Section- the Rich Amine System receives the collected rich amine from the amine absorbers, located in the Diesel Union fining Unit. Sources include the Recycle Gas Scrubber, located in the reactor section
and the stripper Gas Amine Absorber and located in the fractionation section of the Diesel Union fining Unit. Rich amine from the Recycle Gas Scrubber and Stripper Gas Amine Absorber is combined outside battery limit and sent directly to Rich Amine Flash Drum 26-V-01.
Amine Regeneration Section- The Rich Amine flash drum 26-V-01 separates any entrained liquid or gaseous hydrocarbon from the rich amine. Liquid hydrocarbon is separated into a reservoir in 26-V-01 and will be periodically pumped to a slop oil system by slop oil pump 26-P05 A/B. Hydrocarbon vapour separated in 26-V-01, which also contains some H2S is scrubbed with a small lean amine slipstream in the stack portion of the drum. The stacked portion consists of Carbon Raschig Ring random packing to provide intimate contact between the flash gas and the lean amine. The sweetened flash gas flows through back pressure control valve PV-6203 to the acid gas relief header. The drum operates at the pressure of 1.93 kg/cm2g. Rich amine now flows from the bottom of 26-V-01 to Rich amine pump 26-P-01 A/B and then through the tube side of rich lean amine exchanger 28-E-02 A/B. In 26-E-02 A/B the rich amine is heated while the lean
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amine from the bottom of amine stripper 26-C-01 is cooled. The heated rich amine flows through the control valve LV-6202(used to control the level in 26-V-01) and into 26-C-01. Stripper 26-C-01 strips nearly all of the H2S from the rich amine, thus regenerated it to lean amine. The stripper contains 23 valve trays with which 20 trays in the stripping section and 3 trays in the wash section. Stripping steam is generated in the Amine Stripper Reboilers 26-E-03 A/B by vaporising a portion of the water in the column bottoms (lean amine). A small amount of live stripping stream is also injected into one the re-boiler return lines (14-P26-6511) in order to water balance the entire amine system. The stripping stream flows up through the column, helping to evolve H 2S from the rich amine and heating the solvent to boiling point. Reboilers 26-E-03 A/B use de superheated MP stream as the heating medium. The re boiler heating rate is controlled by low selector FY-6502B of steam flow controller FIC-6502 and pressure controller PIC-6507. The absolute maximum temperature of the de superheated steam is 160OC in order to prevent amine degradation Condensate from the re-boilers condensate return system is used as the water source to de-superheat the reboilers heating steam. Condensate from 26-E-03 A/B flows to condensate Drum 26-V-04.Whatever is not used for de superheating water or as makeup water to the Diesel Union fining Unit is pumped to the condensate header with condensate pump 26-P-04 A/B under level control(LIC-6601). Acid gas from the top of 26-C-01, containsH2S, some light hydrocarbons and water vapours is cooled to drop the temperature (Condensing most of the water) to minimise the water loss in the overhead in this overhead steam. The gas is first cooled in Amine Stripper Condenser 26-AC-06 and then further cooled in Amine Stripper Trim Cooler 26-E-04. The two phase stream flows to Amine stripper Receiver 26-V-02 where the water is separated from the remaining acid gas steam. The water from 26-V-02 is pumped via Amine stripper Reflux pump 26-P-03 A/B as reflux back to the top tray of 26-C-01. The acid gas from the top of 26-V-02 is normally to the SRU. At shut down of the SRU or if the SRU is not in operation acid gas is sent to the acid gas relief header through pressure control valve PV-6505B. Theacid gas pressure is controlled with pressure control valve PV-6505 via a split ring configuration at a pressure of 1.77 kg/cm2g. The bottom of 26-C-01 is used as a surge volume for lean amine to a temperature (43.3OC), which can be used by the amine scrubber and
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absorbs in the Diesel Union fining Unit. The outlet temperature of 26-E01 is kept from getting too low by temperature controller TIC-6402. This acts on the lean amine by pass around the trim cooler. The lean amine then flows to the filtration system, which filters approx. 10% slipstream of lean amine through a sense of three filters.
Lean Amine Section- Some lean Amine is used inside the amine unit battery limits as a wash for the Rich Amine flash Drum stack them is also
a start-up line, which allows lean amine to be re-circulated through the regeneration section only, flowing back to 26-V-01. The remainder of the lean amine then leaves the Amine unit and serves the absorbers in the DHDS Unit. These absorbers include: the Recycle Gas Scrubber located in the Reactor section and the Stripper Gas Amine Absorber located in the Reactor Section and the Stripper Gas Amine Absorber located in the Fractionating Section. The Reactor section scrubber operates at a significantly higher pressure than the other absorber, so a booster pump is required to supply the lean amine at a sufficient pressure for the Recycle Gas Scrubber. This pump is located in the Diesel union fining Unit.
Amine Storage Section- High purity amine (99 wt.% DEA) is to
supplied to ARU 26 in bulk quantity (for s/u) and in drums. The Amine Melt Tank 26-V-07 is used to empty drums and to melt the amine. The melted DEA or the DEA in bulk quantity is transferred to Amine Storage Tank 26-T-01 via Amine Transfer Pump 26-P-07 A/B and is diluted to a 25 wt.% solution in water with cold condensate from the refinery as water source. This pump can also be used to mix the contents of 26-T-01 through a recirculation line with a jet mixer located inside the tank. The 25 wt% DEA Solution in water is periodically pumped (via 26-P-07 A/B) to the regeneration section to replenish the amine supply. The amine can be pumped to the suction of Lean Amine Pump 26-P-02 A/B and the suction of Rich Amine Pump 26-P-01 A/B. Addition of amine will result in an increase in the level of Amine Stripper 26-C-01. Amine storage Tank 26-T-01 is also used to old the entire inventory of the Regeneration Section, when it needs to be shutdown. The pump out line is on the lean amine stream just downstream of the Lean Amine Coolers. The cooled lean amine is transferred over to 26-T-01 via 26-P-02 A/B and can be replaced using 26-P-07 A/B when the train is ready to be re-inventoried.
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SULPHUR REGENERATION UNIT Introduction:
The sulphur recovery unit-28/83 of haldia refinery consists of a single train to recover sulphur from acid gases from amine regeneration unit(UNIT-26) and sour water stripper off gases ex refinery sour water stripper(UNIT-29).This unit based on claus recovery concept.It is consisting of one thermal reactor and four catalytic converters for recovery of sulphur from above streams.The equipments in the unit shall be divided into three main sections, namely the thermal reactor section ,claus section and tail gas incineration section.The sulphur recovery section shall include knock out drums for various inlet streams,a main burner,a main combustion chamber,a waste heat boiler, sulphur condenser,catalytic converter-1,catalytic converter-2,catalytic converter-3,and super claus catalytic converter,a sulphur pit to storage liquid sulphur,sulphur pumps,pit ejector etc.The tail gas incineration section includes thermal incinerator burner and vent stack for disposing of the flue gas from incinerator containing sulphur dioxide.Flue gases produced by incinerating the tail gases shall be vented through stack to disperse the sulphur dioxide.Stack is designed for two trains each of 60TPD sulphur capacity.A minimum stack height of 50m is provided.Sulphur recovered in the process is stored in the pit and is pumped to a yard where sulphur lumps are produced by quenching the ,molten sulphur using service water. Sulphur Recovery Rate:
The unit is capable of a sulphur recovery rate of 99 wt% based on operation of the unit at a capacity and acid gas composition corresponding to one of the cases as defined. Unit Capacity: Design Capacity
The unit consists of one SRU with a sulphur production capacity of 60 metric tons/day.
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Turndown Capacity-
The turndown of the unit is 30% on the normal feed gas rate. On-stream Factor per year is 8000 years. Design Feed Chsrscterstics
The feed stock of the SRU is a mixture of the” acid gas ex ARU” and the “Acid gas ex SWS”,the unit should be capable of converting 99% wt of the hydrogen sulphide contained in the feed streams to sulphur in all the following cases.
Case-1, design case
water hydrogen sulphide ammonia hydrogen methane ethane prpopane butane pentane carbondioxide
acid gas ex-ARU (kg/h) 64.10 2658.80 0.30
acid gas ex-SWS (kg/h) 34.10 58.82 16.49 -
total feed (kg/h) 98.20 2717.62 16.49 0.30
3.38 1.36 0.32 1.27 1.71 -
-
3.38 1.36 0.32 1.27 1.71 -
2731.24
109.41
2840.65
Total
Design Product Characteristics
The product sulphur will meet the following specification after degassing
State : liquid sulphur
Colour: bright yellow(as solid state)
Purity: min 99.9wt% on dry basis
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Hydrogen sulphide content: 10ppm weight max.
Process Summary:
The sulphur recovery process applied in design,which is known as the SUPERCLAUS process, is based upon the partial combustion of hydrogen sulphide (H2S) with a ratio controlled flow of air, which is maintained automatically in a correct quantity to accomplish the complete oxidation of all hydrocarbons of 0.5-0.7vol% at the selective oxidation reactor(SUPERCLAUS reactor). In the conventional claus process the air to acid gas ratio is mainted to produce an H 2 S/SO2 ratio of exactly 2/1 in the burner effluent gases.This is known to be the optimum ratio of H 2 S/SO2 for the claus reaction.In this process the air to acid gas ratio is adjusted to achieve an H 2 S/SO2 ratio of greater than 2/1 in the burner effluent. In the other words , the front end combustion is operated on H 2 S/SO2 ratio control H2S-SO2 analyzer AT-0801 is provided on effluent gas stream from the 4 th sulphur condenser to measure the H 2S concentration and to control the trim air to the main burner to achieve the desired H2S concentration at this point in the process.From an overview standpoint, the control philosophy may be summarized as :
If the H2S concentration entering the SUPERCLAUS stage is too high , more air is added to the main burner to create more SO 2 .
If the H2S concentration entering the superclaus stage is too low, less air is added to the main burner.
Process Description:
H2S + 3/2 O2 -> SO2 +H2O +heat The major part of residual H2S combines with SO2 to form sulphur, according to the equilibrium reaction 2H2S +SO2 < -> 3/2 S2 +2H2O - heat By this reaction , known as the claus reaction,sulphur is formed in vapourphase in main burner and combustion chamber .The primary
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function of the waste heat boiler is to remove themajor portion of heat generated in the main burner. The secondary function of the waste heat boiler is to utilize the above mentioned heat to produce MHP steam. The process gas from the waste heat boiler is passed into the 1 st sulphur condenser,where the formed sulphur is removed from the gas. The process gas leaving the sulphur condenser still contains a considerable concentration H2S and SO2, there for the essential function of the following equipment is to convert these components to sulphur. In the 1st ,2 nd and 3 rd reactor stages the H2S and SO2 react again to form sulphur, but this time at low temperatures. In the superclaus stage the remaining H 2S is selectively oxidized to sulphur.For this reason it is essential that the combustion in main burner is such that down stream the 3 rd reactor stage the amount of H 2S in the range of 0.5-0.7 vol% and that the SO2 concentration is as low as possible. Before entering the 1st reactor, the process gas flow is heated by indirect steam reheat to obtain the optimum temperature for high conversion of H2S and SO2 to elemental sulphur and simultaneously a high conversion of COS and CS2 to H2S and CO2. In the 1st reactor the H2S and SO2 react again until equilibrium is reached. 2H2S+ SO2 <->3/8 S 8 +2H2O+heat The effluent gas from the 1 st reactor passes to the 2 nd sulphur condenser. The process gas flow is routed to the 2 nd sulphur reheater , then passed to the 2nd reactorwhere equilibrium is established.The sulphur is condensed rd
in the 3 sulphur condenser. The process gas from the 3 rd sulphur condenser is routed to the 3 rd steam reheater ,then passed to the 3 rd reactor where equilibrium is established.The sulphur is condensed in 4th sulphur condenser.
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SUPERCLAUS SECTION
The process gas from the 4 th sulphur condenser is routed to the 4 th steam reheater, then passed to the reactor.Before it enters the reactor a controlled amount of air is added.Proper mixing isobtained in in a static mixer .In the reactor H2S reacts with oxygen to sulphur according to the reaction.The sulphur is condensed in 5 th sulphur condenser.The sulphur coalesce is installed downstream of the last sulphur condenserto separate entrained sulphur mist.The sulphur condensed and separated in the condensers and coalesce is drained via the sulphur locks and sulphur coller in the sulphur pit.
SULPHUR STRIPPING PROCESS The produced sulphur contains H2S,partly dissolved and partly present in form of polysulphides.The function of this process is to enchance the decomposition of polysulphides and to strip the H 2S from sulphur simultaneously the greater part of H 2S is oxidized to sulphur.This is done by bubbling air through the sulphur. The air decreases the partial pressure of the H2S and causes agitation and circulation of sulphur.In this way the H2S content is reduced from approximately 350 to less than 10 ppm wt.
PROCESS FLOW DIAGRAM:
32
MOTOR SPIRIT QUALITY UPGRADATION UNIT(MSQU)
INTRODUCTION:
Process Chemistry Overview:
Thermodynamics and kinetics- For any chemical reaction, the thermodynamics dictates the possibility of its occurrence and the amount of products and unconverted reactants. In fact, some reactions are 100% completed i.e. all the reactants are converted into products. Other are in equilibrium i.e. part of the reactants are only converted. The amount of products and reactants at equilibrium depends upon the operating conditions and is dictated by the thermodynamics. Note that the thermodynamics does not mention the time required to reach the equilibrium or the full completion of a reaction. Kinetics dictates the rate of a chemical reaction (i.e. the amount of feed that disappear in say, one second). Kinetics (rate of reaction) is dependent upon operating conditions but can also be widely modified through the
use of properly selected catalyst. In other words thermodynamics dictates the ultimate equilibrium composition assuming the time is infinite. Kinetics enables the prediction of the composition after a finite time. Since time is always limited, when reactions are concurrent, kinetics is generally predominant. A catalyst generally consist of a support (earth oxide, alumina, silica, magnesia) on which finely divided metal(s) is/are deposited. The metal is always responsible for the catalytic action. Very often the support has also a catalyst action related to its chemical nature.
Catalyst activity, selectivity, stabilityThe main characteristics of a catalyst other than its physical and mechanical properties are: The activity which is the catalyst ability to increase the rate of the reactions involved. It is measured by the temperature at which the catalyst ability I increased the rate of the reactions involved. It is measured by the temperature at which the catalyst must be
33
operated to produce a product on specification, for a given feed, all other operating conditions being equal. The selectivity expresses the catalyst ability to favour desirable reaction rather than others. The stability characteristics the change with time of the catalyst performance (i.e. activity, selectivity) when operating conditions and feed are stable. It is chiefly the polymers or coke deposit where affects stability, because it decreases the metal contact area. Traces of metal in the feed also adversely affect stability.
Chemical Reaction- The purpose of the Naphtha Hydro treatment unit is to protect the isomerisation catalyst by eliminating or reducing to an acceptable level the impurities present in the naphtha stream. Impurities such as sulphur, nitrogen, water, halogens, di-olefins, olefins, mercury, arsenic and other metals are detrimental to catalytic activity. The treatment process is achieved by passing the naphtha over a bimetallic catalytic bed in an adiabatic reactor in the presence of hydrogen. There are principally two fundamental reactions occurring: -Hydro refining
-Hydrogenation Hydro refining: This refers to the replacement of the contaminant molecule with hydrogen. Major hydro refining reactions include desulphurisation, denitrification and de- oxygenation. These are explained in sections that follow. a) Desulphurisation: Sulphides, disulphides and mercaptans react readily to produce the corresponding saturated or aromatic compound releasing H2S. RSR’ + 2H2 RH+R’H+H2S RSSR’+3H2RH+ R’H+2H2S RSH+ H2 RH+ H2S Sulphur combined in an aromatic structure like thiophene is more difficult to react. b) Denitrification: This reaction occurs at a slower rate than desulphurisation. Here nitrogen is released to form ammonia.
34
R-NH2 + H2 R-H + NH3 c) De- Oxygenation Similar to denitrification, de- oxygenation reactions are much more difficult than desulphurisation. Oxygenated contaminants are not significant problem in virgin naphtha but more prevalent in cracked and synthetic naphthas. In the de- oxygenation reactions, the CO bond is broken and the corresponding saturated aliphatic or aromatic is formed together with water.
+ H2
Phenol
OH
+ H2O
Benzene
Hydrogenation- Hydrogenation or olefin saturation is the addition of hydrogen to an unsaturated hydrocarbon to produce a saturated product. Olefinic hydrocarbons are not normally present in straight run naphthas but can be found in high concentrations in cracked naphthas. The olefin saturation reaction is highly exothermic and proceeds relatively easily and quickly (in top section of the catalyst bed). CH3-CH2-CH=CH-CH CH3-CH2-CH2-CH2-CH3
CH3-CH2-CH2-CH2-CH=CH2 CH3-CH2-CH2-CH2-CH2-CH2-CH3 Olefins at temperature involved in reforming process (about 500 oC) result in coke deposits on the reforming catalyst and hence must be hydrogenated to avoid coke deposition on catalyst. Olefins hydrogenation reactions are exothermic. Heat of reaction is around 30 Kcal/mol. Minimal hydrogenation of aromatics occurs, estimated at less than one per cent. This is a consequence of high selectivity of the AXENS bimetallic catalyst.
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Catalyst characteristicsThere are two catalysts used in the Hydro treatment unit: HR-945(1st bed of the reactor) for Olefins hydrogenation and the HR-448 (2nd bed of the reactor) for the desulphurisation and the denitrification. The main features of all the hydro treating catalysts are: High purity alumina support having a strong resistance to attrition. High stability and selectivity towards the desirable hydro treating
reactions.
Ease of regenerability.
The association of the above qualities gives the following advantages: Efficient hydro treating. Minimal yield loss. Long catalyst life.
Catalyst mechanism: Reaction mechanisms in catalyst naphtha hydro treating are known only for a few reactants and results are not easily generalised. As desulphurisation is the predominant reaction taking place, using thiophene as a model reactant, studies have shown that the first reaction of thiophene is the C-S bond cleavage to form 1,3 butadiene, rather than hydrogenation of the C=C bond. e.g. + 2H2 CH=CH-CH=CH2 + H2S
s Thiophene
Butadiene
The subsequent reaction is then: CH=CH-CH=CH2+2H2 CH3-CH2-CH2-CH3
Process flow description: The following process description includes following sections: -Naphtha splitter -NHDT (Naphtha Hydro treatment) -Reformer splitter
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Naphtha Splitter The straight run naphtha enters the unit at the battery limit conditions (4.0 kg/cm2 g and 40 OC) and is directed to SR naphtha surge drum 85-B-01 is maintained under a pressure of 1.5 kg/cm2g by blanketing with fuel gas using split range pressure controller. The fuel gas blanketing is provided in the surge drum 85-B-01 to maintain constant pressure 1.5 kg/cm 2g in the surge drum is order to avoid ingress of air and formation of explosive mixture. The fuel is admitted to PIC- 0103 when pressures in the surge drum falls below the set point. When the pressure in the surge drum exceeds the set point PIC-0130 releases the pressure to flare header. The naphtha is pumped under flow control FIC-0105 by naphtha splitter feed pump 85-P-01 A/B. One pump is working and other is standby. The stand by pump shall be started manually. The naphtha splitter feed pump 85-P-01 A/B is provided with minimum flow by pass line through flow controller. When the process flow becomes less than pump minimum flow requirement on minimum flow by pass line will open to maintain pump minimum flow. The pump minimum flow by pass line is connected to surge drum 85-B-01 SR naphtha feed inlet line. The naphtha splitter feed is heated by hot naphtha splitter bottoms from 85-P-04 A/B in naphtha splitter feed/effluent exchanger 85-E-01 A/B and enters the naphtha splitter column 85-C-01 on tray #26 at 94 OC. The liquid hydrocarbon is pumped by the naphtha splitter reflux pump and split into 3 parts: 1> One part is sent to the column as reflux under flow control FIC-0101 cascaded with temperature control on tray #37 of splitter column. 2> A part is sent as light naphtha to NHDT unit under flow control FIC0203(slave) that is cascaded with the level controllerLIC0201(Master) in the SR Naphtha surge drum. 3> Rest is mixed under flow control that is cascaded with level controller in the naphtha splitter reflux drum with heart cut and sent to the storage as excess naphtha. A side cut (heart cut) is withdrawn on tray #31 under level control. It is pumped by 85-P-02 A/B (1 working+1 standby) under flow control, mixed with a part of light naphtha and cooled and sent to storage as Excess naphtha. 85-P-03 A/B is provided with minimum flow bypass line.
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The NHDT unit is designed to process light naphtha combined with FCC gasoline heart cut. However, a slip stream of naphtha heart cut may be injected in the light naphtha as NHDT feed. The quantity of naphtha heart cut shall be limited to 30% of the total naphtha fed to the NHDT unit. Heavy naphtha from the naphtha splitter bottom is pumped by 85-P-04 A/B (1 working + 1 standby), cooled by 85-E-01 A/B and 85-E- 04. Then it is sent under flow control with level reset to catalytic reforming unit via storage. Further, the whole process is divided into different sections namely:
Reaction Section
Stripper section
Reformate splitter
Catalyst in- situ regeneration operation.
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ONCE THROUGH HYDROCRACKER UNIT OHCU comprises of three units 1. Hydro cracker 2. Hydrogen Generation unit 3. Nitrogen generation unit
Hydrocracker Feed: Straight run gas oil, Vacuum gas oils, Cycle oils, Coker Gas oils, thermally cracked stocks, Solvent de asphalted residual oils, straight run naphtha, cracked naphtha. Product: Liquefied petroleum gas (LPG), Motor gasoline, Reformer feeds, Aviation turbine fuel, Diesel fuels, heating oils, Solvent and thinners, Lube oil, FCC feed
: Hydro cracking processes involved two types of catalyst 1 Hydro pre treatment catalyst 2 Hydro cracking catalysts 1. Hydro treating (Pre treat) Catalyst The main objective of pretreat catalyst is to remove organic nitrogen from the hydro cracker feed allowing (i) Better performance of second stage hydro cracking catalyst, and (ii) The initiation of the sequence of hydro cracking reactions by saturation of aromatic compounds Pre treat catalyst must have adequate activity to achieve above objectives within the operating limits of the hydrogen partial pressure, temperature and LHSV. 2. Hydro cracking Catalyst: Hydro cracking catalyst is a bi-functional catalyst and has a cracking function and hydrogenation dehydrogenation function. The former is provided by an acidic support whereas the latter is imparted by metals. Acid sites (Crystalline zeolite, amorphous silica alumina, mixture of crystalline zeolite and amorphous oxides) provide
39
cracking activity. Metals [Noble metal (Pd, Pt) or non- noble metal sulphides (Mo, Wo or Co, Ni)] provide hydrogenation dehydrogenation activity. These metals catalyze the hydrogenation of feed stocks making them more reactive for cracking and hetero-atom removal as well reducing the coke rate Zeolite based hydro cracking catalysts have following advantages of greater acidity resulting in greater cracking activity; better thermal/hydrothermal stability; better naphtha selectivity; better resistance to nitrogen and sulphur compounds; low coke forming tendency, and easy regenerability. The unit consists of the following sections: 1. 2. 3. 4. 5. 6.
Furnace First stage Reactor section Second stage Reactor section High pressure separator Fractionation Section Light Ends Recovery section
Effect of Operating Parameters
Various operating parameters affecting hydro cracking are Reaction temperature, Hydrogen partial pressure, Hourly feed velocity of the feed, Hydrogen recycle ratio Temperature increase in temperature accelerates cracking reaction on acid sites and displaces the equilibrium of hydrogenation reactions towards dehydrogenation. Too high temperature limits the hydro cracking of aromatic structure .The pressure influences significantly the equilibrium of dehydrogenation-hydrogenation reactions that takes place on the metallic sites. The increase in pressure for a given molar ratio H2/feed corresponds to increase in the partial pressure of hydrogen, will produce an increase the conversion of the aromatic structures to saturated products which will improve the quality of jet fuel, diesel fuel and oil with very high viscosity index.
40
Effect of Feedstock:
A higher content of aromatic hydrocarbons requires higher pressure and higher hydrogen/feed ratio, the lowest possible temperature and a higher hydrogen consumption of hydrogen and the severity of the process Effects of Feed Impurities:
Hydrogen sulphide, nitrogen compounds and aromatic molecules present in the feed affect the hydro cracking reactions. Increase in nitrogen result in lower conversion. Ammonia inhibits the hydro cracking catalyst activity, requiring higher operating temperatures. Polymeric compounds have substantial inhibiting and poisoning effects. Poly nuclear aromatics present in small amount in the residue deactivate the catalyst.
41
Process Flow Diagram:
42
Hydrogen generation Unit
Purpose-
To cater the refinery hydrogen demand in order to produce low sulphur& high quality products from hydro treater and hydro cracking Introduction: - Hydrogen generation unit was commissioned with a capacity 10,000 metric tonnes per annum of 99.99% pure hydrogen that subsequently increased to 150000 MTPY with a revamp in may 2003. Feed is mixture of naphtha & FCC gasoline in ratio of 80:20 by wt .feed impurities are unsaturated hydrocarbon sulphur& chlorine. Chemical reaction
Basic reaction RSH + H2
RH + H2S
RCl + H2
RH+ HCl
R=R + H 2
R-R
Process description:-it consist of following main process step
1. Pre-desulphurization :- Unsaturated component as well as high amount of organic sulphur is removed from feed by catalytic conversion which is separated from naphtha by distillation R1SS2 + 3H2 R1H + R2H + 2H2S COS + H2 CO + H2S 2. Final desulphurization: - In this further catalytic hydrogenation of the residual organic sulphur followed by adsorption of the hydrogen sulphide on selective adsorbent bed. ZnO bed and CoMox catalyst are used for the removal of the sulphur and chlorine compound RCl + H2 RH + HCl
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3. Pre- reforming:- In this the feed is reacted in presence of steam to give a mixture of methane, carbon dioxide and hydrogen over a nickel bed catalyst CnHm + n H2O
CO + (m+n) H2
CO2 + 4H2 CH4 + 2H2O CO + H2O CO2 + H2 4. Reformer :- In order to achieve high yield of hydrogen from the feed stock after pre reforming methane is converted in reformer which operate at high temperature 5. Shift conversion: - the process gas leaving the reforming section contains carbon monoxide which is converted into CO 2 and hydrogen. The reactor is operated at lowest possible temperature in order to recover the heat and the hydrogen generation from the feed stock. there are two temperature at which reactor are operating high temperature shift and low temperature shift CO + H2O CO2 + H2 6. Pressure swing adsorption :- PSA technology is used to remove impurities form reformer gas this is achieved by molecular sieve which adsorb the contaminant and allow the hydrogen to pass Simplified flow sheet
PREDESULPHURIZATION VAPORIZATION DESULPHURIZATION
PREREFORMER & REFORMER
DUAL STEAM
CONVECTION SECTION
SYSTEM PRESSURE SWING ADSORPTION HEAT RECOVERY AND COOLING
HIGH TEMP. & LOW TEMP. SHIFT CONVERSION
44
PROCESS FLOW DIAGRAM:
Nitrogen Generation Unit
Properties of Nitrogen:
Nitrogen is a diatomic gas which constitutes 78% of the earth atmosphere. Its atomic weight is 14 Physical Properties: Colourless, Odourless, and Tasteless Chemical Properties: 1.Density (at 0 °C and 1 atm): 1.251 g/l 2. Dew Point :: -172 °C
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3. Melting Point: -210 0C 4. Boiling Point : -195.8 0C Properties of Oxygen:
Oxygen is a diatomic gas which constitutes about 21% of the earth’s atmosphere. It is most commonly found in its diatomic form which is molecular oxygen (O2) and the triplet state known as Ozone (O 3) which is a highly active compound. Its atomic wt is 16. Physical Properties: Colourless , Odourless, Tasteless Chemical Properties: 1. Density (at 0 °C and 1 atm) :: 1.432 g/l 2. Dew Point ::
-165 °C 0
3. Melting Point :: -218.4 C 0
4. Boiling Point :: -183.0 C
Raw materials
1- Air Process description:
It consists of following section-Air Compression Section, Refrigeration Section, Pre-Purification Section, Cold Box, and Storage Tanks. Air compression section:-The Air compressors receive air through Air Suction Filter and then pressurized dust and oil free air is discharged to the Refrigeration Section. This Section consists of a 3-stage Compressors Refrigeration Section:-Air enters the Refrigeration section DX Chiller where it is cooled down to a temperature of about 8 to 12 deg C.Refrigerant Used-1,1,1,2 tetra fluoro ethane(R134A).Vaporized R134A returns to the REFRIGERATION COMPRESSOR and is discharged to the CONDENSORS where it is cooled down by cooling water. The
46
liquid R134A is then routed to vapouriser 96-E-14 after exchanging heat with gaseous R134A and partial vaporisation through where it again cools the air by gaining latent heat of vaporisation from the air. Pre-Purification Section:-AIR has been cooled to 8-12 oC at 8.7 kg/cm2, thus a part of Saturated Water is condensed. To separate this moisture air is sent to the Moisture Separator. Then the air is sent to one of the two ADSORBERS . Here moisture traces and CO2 are removed through Activated alumina and Molecular sieve beds respectively. These Adsorbers adsorb impurities at a temperature of about 10 oC and are regenerated at a temperature of around 130 to 180 oC. Thus they are Temperature Swing Adsorbers .The heating for the regeneration is done using an electric REGENERATION HEATER .After having passed through the adsorbers the AIR is the directed to the COLD BOX through FILTERS
Cold box section:-The Cold Box process can be divided into 3 parts: Cooling down and liquefaction of air-: Air enters exchanger and is cooled in counter current flow to outgoing pure N2, waste air coming from column. The air flows out at partly liquid state and enters the lower part of column. Fractionating the air by distillation-: The air coming from exchanger enters the bottom of column below the bed of trays at -165.8 deg C. The vaporizer ensures the cooling down by its Rich Liquid bath and performs condensation of the rising vapour. N2 which is in gaseous state is received from the column top and O2 rich liquid is received from the column bottom. This liquid is further used for the exchange of Cold energy with incoming dry air. Productions of the Column and Vaporizer:-From the top of the Column the pure gaseous Nitrogen is available at about 10 oC after having exchanged heat in counter flow to treated air in exchanger. At the top of the vaporizer 96-E-03 the Waste Air flows out at about 5.58 kg/sq. cm, 171.23 deg C. This Waste Air is utilized expansion turbine, which provides the necessary refrigeration for the plant by expanding the waste air. At the outlet of the exchanger, a part of this Waste Air at about 13 oC and 1.2 kg/sq cm is utilized to regenerate the adsorbent beds of Absorbers. From the liquid receiver at the upper part of the Column a part
47
of the pure Liquid Nitrogen can be drawn off as product. If purity of Nitrogen is more than 3 ppm (vol.) oxygen, the gaseous Nitrogen product is vented off.
Nitrogen Storage: A small portion of the reflux to Column C-01 is sent to Tank T-01 A/B as liquid N 2 storage. In case of Plant Shutdown, and header pressure down, LN (Liquid N 2) is passed to vaporizers (96-E04A/B) which vaporizes LN to Gaseous state and supply to header. These tanks are vacuum insulated so as to prevent the LN from vaporizing inside the tanks. Process Flow Diagram:
48
LUBE OIL BLOCK Lube Oil Block comprises of the following units:
Vacuum Distillation Unit-I (U-31)
Propane De-Asphalting Unit (U-32)
Furfural Extraction Unit (U-33)
Solvent Dewaxing Unit (U-34)
Lube Hydrofinishing Unit (U-35)
Bitumen Blowing Unit (U-36) [now scrapped, as it is made a part of PDA, U-36 R/D manifold] Vis-breaking Unit (U-37)
NMP Extraction Unit (U-38) Wax Hydrofinishing Unit (U-39)
Catalytic IsoDewaxing Unit (U-84) The typical lube oil base stock processing circuit is shown below for Haldia Refinery.
Lube Processing circuit in Haldia Refinery KV, Flash Point
Gas
n o ti la
Crude Oil
Naphtha VGO Kero Diesel
VR
PourPoint
Waxy Raffinates
Vacuum Distillates
n tio la ilt is d m u u c a V
til is d ic r e h p s o m t A
RCO
VI,CCR
n tio c a r t x E t n e v l o S
DAO Propane De-Asphalting
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Colour & Stability
De-waxed oils r o g n i x a w e D t n e v l o S
g n i x a w e D c ti y l ta a C
Lube Base Oils
g in h is n fi o r d y H
150N 500N HN 150BS
I mpor tant Prope r ti es of L ube Oil The major properties for any LOBS are as follows: 1. Ki nematic V iscosity (kV) It dictates the reducing power of the frictional resistance between
two moving parts due to the presence of the lube oil. 2. Vi scosity I ndex (VI ) It
defines the rate of change of kinematic viscosity with temperature, thus governing high temperature applications viz. inside engines or compressor crankcases etc.
3. F lash Poin t It indicates the highest application temperature at which the oil
would work without getting deteriorated. [also this is an indicator of vaporization loss] 4. Pour Poin t It indicates the lowest temperature at which the oil would remain in
liquid state, thereby maintaining its fluidity intact, as because very low temperatures may be encountered in land of caprice climate (e.g. at Leh etc.). 5. Colour Lube Oil Base Stock should be water-like in appearance, the colour
that is seen in most of the marketed lube oils are due to the additives that are added in LOBS. This colour is imparted mainly due to unsaturated/aromatics leftover in the finished LOBS. 6. Oxi dation S tabili ty Oxidation stability is required so as to reduce any chance of
polymerization (due to contact with oxygen at some elevated temperature. This happens due to the presence of unsaturated.
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LOBS
VI
(as per API)
SULPHER
SATURATES
%
%
GROUP I
80-120
>0.03
<90
GROUP II
80-120
<0.03
>90
GROUP III
>120
<0.03
>90
Vacuum Distillation Unit Purpose:-To distil the RCO under vacuum for producing vacuum distillates for preparing feedstock for LOBS manufacturing. Diesel and VR are by products and residue respectively.
Feed
RCO (Reduced Crude Oil) Ex FOB - CDU Bottoms Gas Oil/ Diesel
Products
Spindle Oil Light Oil Inter Oil Heavy Oil Vacuum Residue (VR) or Short Residue (SR)
Unit Capacity Distillation Parameters
250m3/hr, with Arab Mix /Upper Zakum RCO
Pressure
70 mmHg Absolute
Temperature
360-400 C
Licensor/ Technology
IPIP (Romania)
Process Description:-
RCO is preheated in a series of heat exchangers (pre-heat exchanger train) by exchanging heat with the high temperature product streams and then passed through two numbers of fired heaters
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(furnaces) to achieve temperature of ~400 C. This heated stream is flashed in a vacuum distillation column operating with top pressure of 70 mmHg (Abs). Gas oil reflux is given at the top. Also an internal pump around below the Light Oil draw tray helps to remove heat from the column. Products like SO, LO, IO and HO are drawn from different draw nozzles from the column. Each product is stripped with stripping steam in their respective stripper columns to remove the lighter components and thereby increases the flash pints of the products. All these products are cooled in the feed preheat exchangers followed by water or tempered water coolers. VR is drawn from the bottom of the column and is routed to tanks after exchanging heat with the feed stream followed by steam boilers and tempered water coolers. Advantages:-
As the boiling points reduce with decrease in pressure, RCO need not be raised to very high temperature for further distillation. At high cracking phenomena shall get promoted leading to coke formation in pipe lines, columns, vessels etc. Coke deposition is strictly undesired as it leads to blockage/ clogging of pipes and restricts flow leading to unwanted unit interruptions. Vacuum distillation helps to avoid such occurrence. • • • • • • • • •
RCO feed temp : 90-115 deg C Preheat Temp : 285 deg C Coil Outlet Temp : 400 deg C Vac Tower Flash Zone Pr . 120-130 mm Hg at 400 deg C Vac Tower top Pressure 70 mm Hg (Abs) Vac Tower Top Temp : 80 deg C Stripping Steam : 6.5 -10 Mt/hr Product Draw off temp: 232 , 245, 333 & 370 for SO,LO, IO & HO Bottom Quench : 5 m3/hr
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Propane de Asphalting unit Purpose:-
To recover the valuable oil left in the Vacuum Residue from VDU bottoms. Around 25-30 % oil is left in the VR/ SR which can’t be recovered in the VDU. The recovered oil called DAO (De-asphalted Oil) is a very good feed stock for high viscosity LOBS manufacturing. Feed
VR (Vacuum Residue) from VDU bottoms
Products
DAO (De-asphalted Oil) Asphalt
Unit Capacity
800000 MT/Yr
DAO is recovered by means of Extraction process with liquid propane as a solvent. Propane dissolves the oil and rejects the Methodology asphalts. Propane has a reverse solubility for asphalt and thus DAO quality improves with increase in extraction temperature. Pressure
38 Kg/ Cm2(g)
Temperature 60-80 C Propane to 6 to 12 Feed Ratio Licensor/ M.W. Kellog Technology Co. USA Technology
Process description:-
VR feed is diluted with propane solvent and sent to extractor columns C 01A/B/C and C 110. Solvent propane is also fed to the extractor where counter current mass transfer takes place. Propane dissolves the oil part and comes out from the top as DAO Mix (contains around 80% propane) while the asphalt being heavy is withdrawn from the bottom as Asphalt Mix. Propane is recovered both from DAO Mix and Asphalt Mix and re-circulated in the unit again. ROSE (Residual Oil Super Critical Extraction) technology has been used to recover the propane from the DAO Mix phase where DAO Mix Phase is taken to its critical temperature and pressure conditions. The propane at this state is just below its boiling point and gets separated from DAO in a pure form in liquid state.
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Advantages:-
Recovery of high value DAO which can be upgraded to high viscosity LOBS- BN (Bright Neutral) and BP (Bright Pale) grades. BN processing also gives wax in SDU which is further upgraded to high valve Micro Crystalline Wax product in WHFU (U 39). Operating variables:-
Temperature: Rise in extraction temperature rejects more asphalt andRatio: thus DAO quality improves but DAO yield decreases. Propane to Feed Increase in ratio increase yield but degrades the quality.
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E 119
M/U Pum ps
Steam
D A
3 2
s p m u P U / M
Steam H Heater
32
Air fin Cool er
x M O A D
Pro pan e Bull ets E 121 A/B
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To Unit 3 2 E 114 A/B/ C/D
Furfural extraction unit Purpose:-
To remove the aromatic hydrocarbons from the Vacuum Distillates (SO, LO, IO, HO) and DAO for improving Viscosity Index (VI) of the products. Feed Products
Vacuum Distillates (SO, LO, IO, HO) and DAO Raffinates of SO, LO, IO, HO and DAO Extracts of SO, LO, Io, HO and DAO
Unit Capacity
Methodology
515000 MT/ Annum Separation process is Extraction with a solvent named Furfural. The solvent has high affinity for aromatics and dissolves them thereby creating two phases- Raffinate Mix Phase (Lean in aromatics) and Extract Mix Phase (rich in aromatics). Solvent is recovered from both the streams and re-circulated back to the unit after proper drying (removal of water). Raffinate and Extract products are routed to their respective cooling in the preheat exchangers followed bytanks water after coolers.
Pressure
1-2 Kg/ Cm2(g)
Temperature
Top 95-130 C, Bottom 45-80 C
Solvent Ratio
1.2 to 2
to Feed
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Licensor/ Technology
IPIP (Romania)
Process description:-
De-aerated Feed and solvent are fed to an extractor column in a counter current direction where mass transfer takes place. Solvent is in continuous phase while the feed is in the distributed phase. The raffinate mix and extract mix are heated in their respective furnaces and flashed in their respective recovery circuit columns. The flashed vapours are condensed and collected in a solvent dryer column to remove water. The dry solvent is re-circulated back and Raffinate/ Extract products are routed to their respective storage tanks. Operating variables:-
Temperature: Rise in extraction temperature rejects more asphalt and thus DAO quality improves but yield decreases. Propane to Feed Ratio: Increase in ratio increase DAO yield but degrades the quality.
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Solvent De Waxing unit Purpose:-
To separate the wax from the Raffinates obtained from Aromatic Extraction Units (FEU & NMPEU) to lower the pour point of the products. Feed
Raffinates of (SO, LO, IO, HO) and DAO
Products
De-waxed oils of SO, LO, IO, HO and DAO Slack wax of SO, LO, IO, HO and DAO
Unit Capacity
290000 MT/ Annum Extraction and crystallization to achieve de-waxing with the addition of SDA (for BN feed only) followed by filtration & Solvent Recovery Solvent: MEK & Toluene in equal proportions. Toluene is oil
Methodology
solvent & MEK is anti wax solvent. Crystallization is done by chilling using Ammonia as a refrigerant. Vapor ammonia is again compressed and condensed for recirculation
Licensor/ Technology
IPIP (Romania)
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Process description:-
The feed after dilution with the solvent is chilled in a series of Double pipe exchangers (exchanges heat with filtrate) followed by Ammonia chillers. The chilled blend is then filtered in several Rotary Drum Filters where in the wax crystals get separated from the oil phase. The two phase (Lube Mix and Wax Mix phase created by filtration is routed to their respective solvent recovery (by distillation) circuits. Recovered solvent is re-circulated into the system. De-waxed Oil and slack wax are routed to their respective storage tanks. Advantages:-
The process helps to separate the wax components from the raffinates obtained from extraction units. The slack wax obtained as by product during BN feed (DAO) is a suitable feedstock for producing a very high value product called Micro Crystalline Wax (MCW). Operating variables:-
Rotary Filters Dilution Rate Chiller outlet temperatures Vacuum in
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Hydro finishing unit Purpose :-
To improve the colour and the colour stability of lube base stocks Feed
De-Waxed Oils from SDU
Products
Finished LOBS
Unit Capacity
200000 MT / Annum
Process:-
The process is a mild hydro treating one, using a catalyst in presence of Hydrogen at high temperature and pressure. Removes contaminants Sulfur Nitrogen Unsaturates At high hydrogen partial pressure and in presence of the catalyst, Sulfur & Nitrogen in the feed get converted to Hydrogen sulfide and Ammonia respectively. Also unsaturates get saturated resulting in stable products Parameter’s name
Operating range
Reactor’s outlet temperature
220-340 deg C
Furnace COT
210-330 deg C
Reactor dP
0.5-1.5 kg/cm2g (max. 3.5 kg/cm2g)
System pressure
55-60 kg/cm2g
flow/purity Make up H2
400-450 kg/h
Licensor/ Technology
IFP (France)
Process description:-
Feed mixed with hydrogen is passed through preheat exchangers followed by a furnace to reach the desired temperature level. This stream is fed to a reactor. Reactor outlet after cooling is separated
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from the vapors. The liquid part is tripped off of lighter components in a vacuum column. Product from the column bottom is sent to storage. The vapor part after purification is re-circulated back using the recycle compressors. Advantages :-
Production of API Group I LOBS of various grades Operating variables: Reactor temperature System pressure Hydrogen circulation Rate
Vis-breaker unit Purpose:-
To convert the high viscosity feed stock like VR/Asphalt to low viscosity products like VB Tar/ Furnace Oil.
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Feed
Vacuum Residue/ Asphlat/ Heavy Extracts
Products
VB Tar/ FO VB Gas oil, VB Gasolene and Fuel Gas
Unit Capacity
491000 MT/ Annum
Process:-
A mild thermal cracking process, A common process wherein long chain hydrocarbon molecules in heavy feed stocks are broken into small molecules having low viscosity, thereby leading to a viscosity reduction of feed stock.Feed stock is heated to relatively lower temperature (435445 Deg C) in a furnace and partly cracked VB charge is hold in a Soaker Drum for longer residence times (25-30 min) to achieve the required conversion. Process description:The feed after passing through a series of preheat exchanges is fed to a furnace to raise the temperature to around 440 C. This stream is passed through a soaker vessel where a residence time of around 30
minutes is given. The soaker is operated at a pressure of around 10 Kg/ Cm2g. The soaker outlet is fractionated in a column where different products are separated to produce on spec Furnace Oil/ VB Tar. Advantages:-
Up gradation f low value feed stocks to valuable distillates and VB Tar Operating variables:Furnace coil outlet temperature Soaker pressure Residence time Operating parameters:Furnace outlet temperature: 440 – 443oC Back pressure: 10 – 12 kg/ cm2 g. Residence Time: 1200-1800 Second
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NM extraction unit(NMEU)
Purpose:To remove the aromatic hydrocarbons from the Vacuum Distillates (SO, LO, IO, HO) and DAO for improving Viscosity Index (VI) of the products. Feed
Vacuum Distillates (IO, HO) and DAO
Products
Raffinates of IO, HO and DAO Extracts of IO, HO and DAO
Unit Capacity
350000 MT/ Annum Separation process is Extraction with a solvent named NMP (n-Methyl Pyrollidone). The solvent has high affinity for aromatics and dissolves them thereby creating two phases- Raffinate Mix Phase (Lean in aromatics) and Extract Mix Phase (rich in aromatics). Solvent is recovered from both the streams and re-circulated back to the unit after proper drying (removal of water). Raffinate and Extract products are routed to their respective tanks after
Methodology
Pressure
cooling in the preheat exchangers followed by water coolers. 1-2 Kg/ Cm2(g)
Temperature
Top 70-95 C, Bottom 60-85 C
Solvent to Feed Ratio
1.2 to 2
Licensor/ Technology
IIP/ EIL
63
Process description:-
De-aerated Feed and solvent are fed to an extractor column in a counter current direction where mass transfer takes place. Solvent is in continuous phase while the feed is in the distributed phase. The raffinate mix and extract mix are heated in their respective furnaces and flashed in their respective recovery circuit columns. The flashed vapors are condensed and collected in a solvent dryer column to remove water. The dry solvent is re-circulated back and Raffinate/ Extract products are routed to their respective storage tanks . Operating variables:Temperature: Rise in extraction temperature rejects more asphalt and thus DAO quality improves but yield decreases. Propane to Feed Ratio: Increase in ratio increase DAO yield but degrades the quality.
Wax hydro finishing unit Purpose: -
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To improve the colour and the colour stability of De-oiled wax obtained from SDU. Feed
De-oil wax from SDU
Products
Micro Crystalline wax
Unit Capacity
15000 MT / Annum The process is a mild hydro treating one, using a catalyst in presence of Hydrogen at high temperature and pressure. Removes contaminants Sulfur Nitrogen Unsaturates At high hydrogen partial pressure and in presence of the catalyst, Sulfur & Nitrogen in the feed get converted to Hydrogen sulfide and Ammonia respectively. Also unsaturates get saturated resulting in stable products
Process
Sl. No. 1
Parameter Make up H2 flow
Operating Range 400-500 kg/h
2 3
System pressure F-01 COT
80-130 kg/cm g ~300-330 deg C
Licensor/ Technology
IFP (France)
Process description:-
Feed mixed with hydrogen is passed through preheat exchangers followed by a furnace to reach the desired temperature level. This stream is fed to a reactor. Reactor outlet after cooling is separated from the vapours. The liquid part is tripped off of lighter components in a vacuum column. Product from the column bottom is sent to storage. The vapour part is purged to Sour fuel gas header. Advantages:-
Production of high value Micro Crystalline Wax Operating variables:-
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Reactor temperature ,System pressure, Hydrogen circulation rate.
Catalytic Iso De Waxing unit Purpose:-
Catalytic De-Waxing unit has the objective of producing superior grade Group II LOBS. Feed
Raffinates of (SO, LO, IO, HO) and DAO
Products De-waxed oils of SO, LO, IO, HO and DAO Heavy Distillates, Light distillate and Unstabilized Naphtha Unit Capacity
200000 MT/ Annum of De-waxed Oil
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Conversion of Wax component in Raffinate feed to Non- waxy components Process is isomerisation of the N-Paraffins to Iso-Paraffins N Paraffins - Waxy Nature Iso- Paraffins - Non Waxy Nature Feed is purified in a Hydrotreament Reactor and then de-waxed in the De-waxing reactor followed by a Hydro-finishing reactor. Vacuum fractionation of the De-waxed, Hydro-finished product for on grade dewaxed oil products.
Methodology
Licensor/ Technology
Operating Variables
Exxon Mobile (USA) System pressure Reactors Temperature Space velocity in the Reactors Hydrogen Circulation Rate
Parameter Make up H2 flow System pressure R-01 WART R-02 WART R-03 WART to H2HC flow ratio
Operating Range 3500-5500 Nm /h 112.5 kg/cm g
320-365 deg C 320-365 deg C 225-260 deg C 500-650 Nm /m liquid feed
Process Description: -
Feed after preheating is elevated to high temperature in a furnace and fed to the HDT reactor. The sweetened feed is stripped off H2S + NH3 in a stripper with pure hydrogen gas and fed to the dewaxing reactor after elevating to a designated temperature in a furnace after pre-heating. The de-waxing reactor outlet is then fed to a hydrofinishing reactor. Vapours after separation in a high pressure separator is recycled back to the system. The liquid part from the stripper is fractionated in stages to remove the lighter components for achieving desired specifications. Vapours from Hydrogen stripper are sweetened in an amine wash followed by a water wash column and the sweet gas is recycled in to the system. Advantages :Production of Group II LOBS with increased yield.
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OIL MOVEMENT & STORAGE BLOCK Imported crude, brought by tankers, stored in Refinery's storage tanks is processed successively in different units and finished petroleum products are obtained, which are despatched for marketing by tankers, barges, wagons, trucks, pipeline, drums, cylinders etc.
The process is a continuous one and the Oil Movement and Storage Division (OM&S) of the production department plays an important role in maintaining smooth, continuous operation of the Refinery. The broad functions of OM&S are listed as follows :o
Receipt and storage (a) Crude oil from tankers (b) Intermediate and Finished products from process units.
o
Preparation and supply of feed to various units.
o
Blending of products. & certification of products.
o
Despatch of certified products.
o
Supply of Internal fuel oil to all Furnaces.
o
Unloading, storing and supplying various solvents and chemicals to units.
o
Recovery of steam condensate.
o
Accounting of petroleum products and observing necessary customs and excise formalities.
o
Effluent Treatment.
OM&S IS SUBDIVIDED INTO FOLLOWING AREAS FOR OPERATIONAL CONVENIENCE
Crude tanker unloading.
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Crude tank farm including MCO Tank Farm.
LPG storage area.
LPG Bottling plant & Bulk Truck Loading.
El, E2, E3 tank farms .
E4,E6 Tank farms.
Fl, F2, F7 Tank Farms.
F3 tank farm.
Tank wagon loading.
Tank Truck loading.
700 tank farm
750 tank farm and condensate recovery station.
800 tank farm.
850 tank f arm.
900 tank farm.
950 tank farm.
Bitumen cooling unit.
Bitumen drums filling station and Bulk despatch .
Bitumen Emulsion
Micro-crystalline Wax Palletizing unit .
Solvent tank farm.
Effluent treatment plant.
Accounting.
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CONCLUSION From CDU and VDU, We get to know how physical separation different products occur and various process equipments and unit operations. From DHDS, KHDS & SRU, we get wide knowledge of sulphur recovery which is much important for environmental aspects. Today LPG & Gasoline are important for automobile and domestic purpose, but from CDU, we get less amount of LPG and Gasoline than our requirement. So, the RFCCU supplies the additional LPG and Gasoline requirement. Haldia refinery is only refinery which also takes an important role for lube oil production and separation of aromatics wax and asphalt from lube oil is very much important. Although we could not get enough time to go through all the processes under operation plant, the training helped us to deepen our knowledge regarding the application of mass transfer, heat transfer, fluid mechanics and thermodynamics which are the basics of chemical engineering.
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