Refinery Overview We will see Crude and its characteristics Typical Refinery Configuration Major refinery Process 1.Distillation (CDU/VDU) 2.Alkylation 3.Merox 4.FCC ( For gas oils) 5.Catalytic Cracking (Naphtha) 6.Hydro treating and Cracking 7.Delayed Coking 8.Sulphur Block unit (Sulphur, Sour water stripper, Amine regeneration units) Questions ??? ELEMENTAL COMPOSITION(%)RANGES FOR CRUDE 3 Carbon 83.9-86.8 Hydrogen 11.0-14.0 Sulphur 0.06-8.0 Nitrogen 0.02-1.7 Oxygen 0.08-1.8 Metals 00-0.14 Mainly vanadium and Nickel (Iron, magnesium ,Aluminum , Copper, Silver in traces) PRINCIPAL TYPES OF HYDROCARBON PRESENT Composition of Crude oil Paraffins: Straight chain compounds. Lighter ones are gas, heavier molecules are liquid (oil) and solid (wax). • Naphthenes: consist of carbon rings, with or without side chains; saturated with hydrogen; Naphthenes are chemically stable. Lighter Naphthenes are liquids but heavier ones could be solid. • Aromatics: compounds having a ring of 6 carbon atoms-Bz structure they are relatively unstable. 4 Paraffins 5 Naphthenes 6 Aromatics 7 Classification of Crude oil Gravity as basis API Gravity = 141.5 - 131.5 Sp. Gravity API Gravity is higher for lighter crude and lower for heavier crude. Lighter Crude API>350 e.g, Mumbai High crude 400API Medium Crude API between 250 &340 e,g, Arabian crude: 340API Heavy Crude API<240 API e.g Venezuelan crude 150API DIFFERENCE BETWEEN PARAFFINC & NAPTHENIC BASE Paraffinic SP.gravity of crude Low Yield of gasoline High Octane no.(St. run) Low Sulphur content Low Smoke pt. Kerosene High Cetane value HSD High Pour point of HSD High Napthenic High Low High High Low Low Low 9 • Processing Schemes vs. type of Crude oil Refinery processing scheme and product yields depend on type of crude in terms of chemicals nature and gravity. Typically: • Paraffinic crudes are good for straight run fuel production e.g diesel. • Light crude yields more gasoline. • Medium crude good for diesel production. • Heavy crudes give better bitumen 10 • Naphthenic crude good for Lubricating oil. Flow scheme of a modern refinery 11 Reactions Resulting in Corrosion MgCl2 + H2O Mg(OH)2 +2HCL MgCl2 + H2 S MgS +2HCl Fe + 2HCl FeCl2 +H2 FeCl2 + H2S FeS + 2HCl Fe + H2S FeS + H2 HCl attacks heater tubes, trays, lining, OVHD condenser Corrosion controlled by neutralizing amine injection and filming amines as inhibitors DESALTED CRUDE TRANSFORME R DESALTER LDT PDI CRUDE AT 120 - 140 DEG C PROCESS WATER 100-120 DEG C LDCV Water – Crude Emulsion Distillation of Crude Oil Atmospheric Distillation Column • Typical 40 to 50 actual trays • No. of trays from bottom 4 to 6 bottom stripping 4 to 6 flash zone/heavy gas oil 4 to 6 heavy gas oil/light gas oil 4 to 6 light gasoil/kerosene 4 to 8 kerosene/heavy naphtha 4 to 8 heavy naphtha/light naphtha 2 to 3 pump arounds each • Top temperature: 80 to 100 above water dew point (120 0 to 1300C typical) Flash zone below cracking temperature: 385 0C typical Crude Distillation • • • • • Pump around Typically at product draw tray return 2 to 3 trays above 60 to 800c temperature drop Stripping steam Bottom: 18 to 24 kg /std m3 of RCO Side strippers: 12 to 18 kg /std m3 of stripped product Typical Op. Condns. of Crude Column Crude Type Op. Parameters REF. DRUM Pr., Kg/cm2(a) temp., deg. C COL. TOP Pr., Kg/cm2(a) temp., deg. C FL. ZONE Pr., Kg/cm2(a) temp., deg. C O/F % COT temp., deg. C 30 deg. API 40 deg. API 3.0 45 3.5 103 3.9 384 4 to 6 387 3.1 45 3.6 114 4.0 362 4 to 6 364.5 Vacuum Distillation DRY Top pressure mmHg a Flash zone pressure mmHg a Heater outlet temp.0C Column dia Steam Nil 8 24 395 DAMP 25 42 405 Highest Int Int Highest 420 Least 75 95 WET Economics normally in favor of damp vacuum COLUMN INTERNALS Crude Distillation Column 22 23 Vacuum Distillation Column Alkylation Alkylation combines low-molecular-weight olefins (primarily a mixture of propylene and butylene) with isobutene in the presence of a catalyst, either sulfuric acid or hydrofluoric acid. The product is called alkylate and is composed of a mixture of high-octane, branched-chain paraffinic hydrocarbons. Alkylate is a premium blending stock because it has exceptional antiknock properties and is clean burning. The octane number of the alkylate depends mainly upon the kind of olefins used and upon operating conditions. 24 Merox Process Mercapton extactibility into NaOH solution Mercapton CH3SH C2H5SH nC3H7SH nC4H9SH tC4H9SH nC6H13SH nC9H7SH - % extracted 99.7 98.7 93.0 78.1 21.0 13.7 0.7 Chemistry RSH + NaOH ↔ NaSR + H2O 4NaSR + O2 + 2 H2O → 4RSH + O2 → (1) (2) 4NaOH + 2RSSR 2RSSR + 2 H2O (3) Reaction (1) is reverssible and favourable in forward directions, For Low molecular weight mercaptans. Low temperature. High Caustic concentration. operating conditions Equipments Temperature ( 0C) 45 45 Pressure (Kg/cm2g) 19.5 18 17.5 3.5-5.5 3 Caustic prewash column 1st stage CFC caustic wash contactor 2nd stage CFC caustic 48 wash contactor Oxidizer Tower CFC solvent wash contactor 52 52 CATALYTIC REFORMING CATALYTIC REFORMING IS AN IMPORTANT PROCESS PETROLEUM REFINING AND PETROCHEMICALS INDUSTRIES. IN VALUE ADDITION TO STRAIGHT RUN NAPHTHA AND HAS SIGNIFICANT INFLUENCE ON OVERALL ECONOMICS OF THE INDUSTRY CATALYTIC REFORMING PROCESS BASICALLY CONVERTS PARAFFINS AND NAPHTHENES TO HIGH OCTANE AROMATIC COMPONENTS AND THEREBY PRODUCES HIGH OCTANE MOTOR GASOLINE BLENDING STOCK RICH CONCENTRATES OF AROMATICS VIZ. BENZENE, TOLUENE AND XYLENES (BTX) H2 REQUIRED IN REFINERY FOR HYDROTREATING / HYDROCRACKING, THUS MAKING MORE ECONOMIC VIABLE PROCESS LPG –AN ANOTHER VALUE ADDED PRODUCT. SCHEMATIC OF THE CCR PLATFORMING PROCESS DEHYDROCYCLISATION OF PARAFFINS CH2 CH2 CH2 1 CH2 CH2 CH2 + H2 CH3 CH2 CH2 CH3 CH2 CH2 C7 H14 CYCLISATION CH2 CH3 C7 H16 (O.N. = 0) 3 DEHYDRO- H2C H2C H2C 2 CH2 CH2 CH2 3H2 + TOLUENE (O.N. = 120) GENATION METHYL CYCLEOHEXANE Fluid Catalytic Cracking Oil is cracked in the presence of a finely divided catalyst, which is maintained in an aerated or fluidized state by the oil vapours. The fluid cracker consists of a catalyst section and a fractionating section that operate together as an integrated processing unit. The catalyst section contains the reactor and regenerator, which, with the standpipe and riser, form the catalyst circulation unit. The fluid catalyst is continuously circulated between the reactor and the regenerator using air, oil vapors, and steam as the conveying media. Preheated feed is mixed with hot, regenerated catalyst in the riser and combined with a recycle stream, vapourized, and raised to reactor temperature (485-540°C) by the hot catalyst. As the mixture travels up the riser, the charge is cracked at 0.7-2 bar. In modern FCC units, all cracking takes place in the riser and the "reactor" merely serves as a holding vessel for the cyclones. Cracked product is then charged to a fractionating column where it is separated into fractions, and some of the heavy oil is recycled to the riser. 32 The basic process of catalytic cracking Hydrocarbon feed is brought into intimate contact with hot catalyst The feed is vaporized and “cracked” and leaves behind “coke” The vapors and catalyst are separated The vapors flow into a separation section The coke-laden catalyst is brought into contact with air The coke “burns” and leaves behind hot “regenerated” catalyst The hot catalyst is brought into intimate contact with hydrocarbon feed and the cycle continues….. Fluid Catalytic Cracking 34 Process flow diagram - HCU M/U H2 KA003A/B/C 3600 RECYCLE H2 C/170 Kg/Cm2 RGC HHPS. Gas 1.482 T/H LPG 3.874T/H VV13 CC-05 CC-06 KA002A VGO/CGO VV-1 VV-2 RB-01 157 kg/cm2 VV-4 CLPS off gas To H2 UNIT 35 kg/cm2 VV-6 VV10 LT. NAPH. @14.57T/H 1.1kg/cm2 154 M3/Hr FF-01 GN001 R.H2 3870 C/170Kg/cm2 CHPS CLPS HY. NAPH. @0.558T/H RB-02 2200C VV-3 VV-5 CC-01 380 SKO 71.131T/H HSD 48.894T/H HHPS 4100C RB-03 FF-02 4130C 568KW 2nd STAGE PRT HLPS FF-3 141 m3/Hr Process Chemistry Desulfurization R R CH SH + H2 Denitrification RCH2CH2CH2NH2 + H2 R CH 2 R + H2S RCH2CH2CH3 + NH3 In the reactors, sulfur and nitrogen are removed from the feedstock. In general, the carbon skeleton of the feed molecule is not altered by heteroatom removal; however, the boiling point of the molecule decreases by 27-54 ° C for sulfur compounds and up to 104°C for nitrogen compounds. Olefin saturation RCH2CH=CH2 + H2 Hydrocracking RCH2CH2CH2CH3 + H2 RCH2CH2CH3 RCH3 + CH3CH2CH3 Hydrodemetallization (HDM) Fig. 5 Reaction mechanism for HDM Hydrodesulfurization (HDS) Fig. 6 Postulated mechanism for Hydrodesulfurization Fig. 7 Typical Desulfurization reactions Hydrodenitrification (HDN) Fig. 8 Postulated mechanism for Hydrodenitrification Fig. 9 Typical Denitrification reactions Typical Heteroatoms Types of sulphur compounds Mercaptans Aliphatic Sulfide Disulphide Thiophenes S C C C S R-SH R-S-R R-S-S-R C C S C C Benzo-thiophene C Nitrogen compounds Pyrrole HN Indoles NH Carbazoles NH Pyridine, quinolines & acridines N N N Oxygen compounds Furan, Carboxylic acids & phenols OH Aromatics Benzene, Tetralin & biphenyl Naphthalenes and anthracenes H2 Consumption & Heat Release Reaction Desulphurization Denitrification Olefin Saturation Aromatic Saturation • Hydrogen Consumption 3 mol H 2 per mol of Sulfur 5 mol H 2 per mol of Nitrogen 1 mol H 2 per mol of C=C 3 mol H 2 per mol of ring Saturated. BTU/SCF 60 65-75 130-160 70-85 Heat Release “Thumb Rule” : 130 BTU/SCF for Olefin Saturation. 60 BTU/SCF for every thing else. Typical Classes Of Molecule in Hydroprocessing Paraffins Iso-paraffins Olefins (mono) Olefins (di) Naphthenes Aromatic (mono) Aromatic (di) Aromatic (poly) Poor Pour,Cloud, Octane ; Good Cetane Good Octane Good Octane (comes from FCC & Coker). Foul Hydroprocessing equipment and catalyst. Poor Octane, Acceptable Cetane Good Octane (Large amount in FCC Product) Good Octane, Poor Cetane. Foul Hydroprocessing Catalyst Order Of Reaction Demetalization (Metals Removal From Feed) Olefin Saturation (Destroy Double Bond With H 2) Desulfurization (Sulfur Removal From Feed) S + H 2 H 2S Denitrification (Nitrogen Removal From Feed) N + H2 NH3 Aromatics Saturation Cracking (Lower Boiling Point C12 C 8 + C4 H2 EASY HARD DCU FLOW DIAGRAM EA-06 P-1.75Kg/cm 2 T-115oC 445oC, 2.5 kg/cm 2 BFW STEAM GEN SS CC-02 OFF GAS # 43 VV-02 # 37 # 35 425oC 183oC SOUR WATER #29 # 27 CC-03 KERO-I CC-01 RB-01 RB-02 GO CR #25 251oC 293oC CC-04 KERO-II FF-01 GO HGO RFO SWITCH VALVE HGO CR # 20 VV-01 341oC Slop 502 oC 320oC PREHEAT Hot VR Cold VR OPERATING CONDITIONS • HEATER OUTLET TEMPERATURE, oC 480 – 510 • COKE DRUM TEMPERATURE, oC 440 – 465 • COKE DRUM PRESSURE, Kg/cm2 1–5 • RECYCLE RATIO, VOL/VOL%OF FEED 10 – 100 • CYCLE TIME 24 hrs INTRODUCTION To VISBREAKING The atmospheric or vacuum residual oils are very viscous and have high pour points. It is difficult to pump them as fuel oil. Therefore, they must be blended with relatively high value distillates to meet the finished product viscosity specification. Visbreaking, a thermal conversion process has been found to be a good process which reduces the viscosity and pour point of processed residues. To meet the fuel oil specifications, a small quantity of diluents or cutter stock (Light Gas Oil) may be required. Visbreaking also produces a small amount of light gases and gasoline. VISBREAKING A mild liquid phase thermal conversion process to reduce viscosity and pour point of residues (coke formation avoided) for producing lower viscosity product suitable to use as stable fuel oil. Products include: • VISBROKEN GASES (UP TO C4-) • VISBROKEN NAPHTHA (UP TO 150 oC) • VISBROKEN FUEL OIL (150 oC+) OPTIONS FOR REFINERS Production of visbroken gas oil to be used as diesel Production of visbroken vacuum gas oil to be used as feed stock for FCC operation Production of visbroken vacuum residues to be used as refinery fuel oil TYPICAL COMBINATION CRACKING UNIT Main Fractionator Gas Feed Visbreaker Heater Gasoline Gas Oil Vacuum Recycle Heater Vac.Fractionator Residue Operating conditions: Visbreaking temp. - at the heating coil outlet range from 450 - 500 °C, depending on the design of the unit and the nature of the feed stock. Pressure - may vary between 4 and 20 bars, but higher pressure is often preferred, since this gives greater control over residence time by minimizing vaporization. Residence Time – Temperature and residence are interchangeable within certain limits AN OVERVIEW OF SRB SRB ARU ATU SWS SRU H2S RICH GAS NH3 RICH GAS TAIL GAS inci S.W.EXDCU FUEL GAS FLUE GAS (<10ppmH2S) S.W.ex HCU SWS SOUR GAS 90*C STRIPPED WATER (< 50 ppm H2S )SWEET FUEL GAS ( <1.0 %H2S ) ACID GAS 40*C CONDENSAT B / D E SWS WWTP SRU LIQ. SULFUR SOUR FUEL GAS Ex DCU RICH AMINE L P ABS H P ABS SOUR FUEL GAS Ex HCU GSU LEAN AMINE 45*C ( <10% H2S) ARU SOUR WATER Claus Process H2S CatalyticConverter Converter Catalytic LP Steam S liquid O2 200 - 3500C (340 - 6600F) Sulphur Condenser Further Treatment 130 - 2000C (270 - 3900F) S Yields in the range of 80 – 90% 3 H2S + 3/2 O2 3/x Sx + 3H2O 1/18/2013 55 Modified-Claus Process H2S Reaction Furnace HP steam 925-12500C O2 Wasteheat exchanger Catalytic converter (1700-23000F) 170-3500C (340-6600F) LP steam S liquid Sulphur condenser 130-2000C (270-3900F) Further treatment 1/18/2013 56 CLAUS PROCESS THE CONVENTIONAL CLAUS PROCESS WAS DELOVEPED C. F. CLAUS. THE PROCESS WAS LATER MODIFIED BY I. E. FRABEN THE PRESENT PROCESS CONSISTS OF A THERMAL STAGE FOLLOWED BY TWO OR THREE CATALYTIC RECTOR STAGES. THE THERMAL STAGE CONSISTS OF REACTION FURNACE, WASTE HEAT BOILER AND CONDENSER. IN THIS STAGE, H2S IS OXIDISED BY COMBUSTION AIR TO SO2 ACCORDING TO THE REACTION. 3H2S +3/2O2 2H2S + SO2 +H2O EACH CATALYTIC STAGE CONSISTS OF FEED HEATER, CATALYIST BED AND SULPHUR CONDENSER. CHEMICAL THERMODYNAMIC EQUILIBRIUM IS ESTABLISHED IN EACH BED ACCORDING TO THE CLAUS REACTION 2H2S + SO2 3/n Sn + 2H 2O FOR MAXIMUM SULPHUR RECOVERY, IT IS IMPORTANT TO MAINTAIN H2S : SO2 MOLE RATIO OF 2:1. DEPENDING UPON THE H 2S CONCENTRATION IN THE FEED. REACTION FURNACE MAIN REACTIONS H2S + SO2 S + H2O 2H2S + SO2 2H20 + 3S 2NH3 + O2 3H2O + N2 SIDE REACTIONS CH4 + 2O2 CO2 + 2H2O CO2 + H2S COS + H2O COS + H2S CS2 + H2O 2H2S + HEAT 2H2 + S2 N2 WPC 1001 SOUR WATER STRIPPER WPC 1101 WPC 1102 FLAR E H2S RICH GAS SRU-VV02 S/D SDV 1007 S T R I P P E R WF C 1002 I EE-04 WLC 1106 CBD WLC 1102 EE-05 II WTC 1107 WPC1201 WFC 1105 WTC 1205 EA-02 PA 02 WFF C 1102 SM WTC 1103 EA-01 PA-04 WFC 1202 FLAR E INCI . SRU-VV02 WFC 1203 TO EE01 SDV S.W, ex GSU1004 C W FM COOLER EE001 S.W.ex DCU SW WLC 1004 S.W. TANK WFC 1101 PA 005 S T R I P P E R WFFC 1201 SL S.W. ex HCU SW EE 03A/B WLC 1201 PA 001 STD.W. COOLE R TO DCU/ETP EE 002 PA 003 SOUR WATER NITRGEN AND SULPHUR COMPOUNDS IN CRUDE OILS REFINING PROCESSES H2S + NH3 AMINE TREATING (-H2S) NH3 WATER WASH WATER CONTAINING NH3 WITH SMALL AMOUNTS OF H 2S SOUR WATER COMPOSITION NH3 100 – 5000ppmw H2S 100 – 10000ppmw CH, PHENOL, HCS, CO2, COOH, S-, M+ ADVERSELY AFFECTS BOILOGICAL LIFE. TREATED BEFORE DISCHARGING How much do we use? 63 Imagine a lake 10 miles long, 9 miles wide and 60 feet deep. Fill that lake with oil. That would be about as much oil as the entire world uses in one year. The United States would use about 1/4 of it. THANK YOU 1/18/2013 64 IOCL MATHURA REFINERY LPG N NAP H2 Plant ST RUN NAPH MS MSQP CRU DHDS NAPH DIESEL NAPH LHT NAPH HVY NAPH KERO DIESEL FCC TCO REFORM FCC LT GASO C HVY NAPH ATF KERO S L D OHCU DHDT DIESEL U AGO V AR LPG VGO VR D U FCCU VBU VB NAPHTHA LIQ FUEL VR BBU BITUMEN VB TAR RELIANCE JAMNAGAR REFINERY COMPLEX Sat Gas Concn Sat LPG C3/C4 MEROX Naphtha LPG Normal Butane Recovery N- Butane Light Kerosene Kero MEROX Heavy kerosene Diesel HAGO FCCU Unsat gas conc. LPG MEROX H2 Propylene Recovery Unstabilised Naphtha C5 - C10 CRUDE C D U DHDT H2 PLANT Gasoline to Storage ATM Residue V D U Gasoline MEROX C5 -C6 NC 6 / BN LPG Vacuum Resid LIGHT NAPH HDT Coke to PP Delayed Coker VGO HDT HEAVY NAPH HDT Diesel Source K J Pai, L &T Source K J Pai, L &T Source K J Pai, L &T 3-D Model View Fig. 3 Construction status - Refinery Fig. 4 HCU / DHT Overall Progress:92.8% 71 Overview of Reliability Concerns for Hydroprocessing Plants Richmond Isomax Fire 1989 Brittle Fracture Brittle Fracture Richmond steam generator brittle fracture during hydrotest TANKAGE AREA Essar Oil Refinery, Vadinar Reaction section Riser (reactor) Maintains the feed and the catalyst in close contact as a well-dispersed mixture while avoiding backmixing Designed to minimise catalyst sticking to the walls Reaction section Riser Termination Device Designed to eliminate post-riser cracking thermal / secondary Stripping zone Designed to keep hydrocarbons out of the regenerator Reactor internals Vapors to fractionator Secondary cyclones Riser Termination device Stripper baffles Catalyst to regen