PETROLEUM REFINING OPERATIONS.
A.
INTRODUCTION. Petroleum refining begins with the distillation, or
fractionation, of crude oils into separate hydrocarbon groups. The resultant
products are directly related to the characteristics of the crude processed.
Most distillation products are further converted into more usable products by
changing the size and structure of the hydrocarbon molecules through cracking,
reforming, and other conversion processes as discussed in this chapter. These
converted products are then subjected to various treatment and separation
processes such as extraction, hydrotreating, and sweetening to remove
undesirable constituents and improve product quality. Integrated refineries
incorporate fractionation, conversion, treatment, and blending operations and
may also include petrochemical processing.
B.
REFINING OPERATIONS. Petroleum refining processes and operations can be separated
into five basic areas:
1.
Fractionation (distillation) is the separation of crude oil in atmospheric and
vacuum distillation towers into groups of hydrocarbon compounds of differing
boiling-point ranges called "fractions" or "cuts."
2.
Conversion processes change the size and/or structure of hydrocarbon
molecules. These processes include:
§ Decomposition (dividing) by thermal and
catalytic cracking;
§ Unification (combining) through alkylation and
polymerization; and
§ Alteration (rearranging) with isomerization and
catalytic reforming.
3.
Treatment processes are intended to prepare hydrocarbon streams for
additional processing and to prepare finished products. Treatment may include
the removal or separation of aromatics and naphthenes as well as impurities and
undesirable contaminants. Treatment may involve chemical or physical separation
such as dissolving, absorption, or precipitation using a variety and
combination of processes including desalting, drying, hydrodesulfurizing,
solvent refining, sweetening, solvent extraction, and solvent dewaxing.
4.
Formulating and Blending is the process of mixing and combining
hydrocarbon fractions, additives, and other components to produce finished
products with specific performance properties.
5. Other Refining Operations include: light-ends
recovery; sour-water stripping; solid waste and wastewater treatment;
process-water treatment and cooling; storage and handling; product movement;
hydrogen production; acid and tail-gas treatment; and sulfur recovery. Auxiliary operations and facilities include: steam and power generation; process and fire water systems; flares and relief systems; furnaces and heaters; pumps and valves; supply of steam, air, nitrogen, and other plant gases; alarms and sensors; noise and pollution controls; sampling, testing, and inspecting; and laboratory, control room, maintenance, and administrative facilities.
OVERVIEW OF PETROLEUM REFINING PROCESSES
Process name
|
Action
|
Method
|
Purpose
|
Feedstock(s)
|
Product(s)
|
FRACTIONATION PROCESSES
|
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Atmospheric distillation
|
Separation
|
Thermal
|
Separate fractions
|
Desalted crude oil
|
Gas, gas oil, distillate, residual
|
Vacuum distillation
|
Separation
|
Thermal
|
Separate w/o cracking
|
Atmospheric tower residual
|
Gas oil, lube stock, residual
|
CONVERSION PROCESSED--DECOMPOSITION
|
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Catalytic cracking
|
Alteration
|
Catalytic
|
Upgrade gasoline
|
Gas oil, coke distillate
|
Gasoline, petrochemical feedstock
|
Coking
|
Polymerize
|
Thermal
|
Convert vacuum residuals
|
Gas oil, coke distillate
|
Gasoline, petrochemical feedstock
|
Hydro-cracking
|
Hydrogenate
|
Catalytic
|
Convert to lighter HC's
|
Gas oil, cracked oil, residual
|
Lighter, higher-quality products
|
*Hydrogen steam reforming
|
Decompose
|
Thermal/ catalytic
|
Produce hydrogen
|
Desulfurized gas, O2, steam
|
Hydrogen, CO, CO2
|
*Steam cracking
|
Decompose
|
Thermal
|
Crack large molecules
|
Atm tower hvy fuel/ distillate
|
Cracked naphtha, coke, residual
|
Visbreaking
|
Decompose
|
Thermal
|
reduce viscosity
|
Atmospheric tower residual
|
Distillate, tar
|
CONVERSION PROCESSES--UNIFICATION
|
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Alkylation
|
Combining
|
Catalytic
|
Unite olefins & isoparaffins
|
Tower isobutane/ cracker olefin
|
Iso-octane (alkylate)
|
Grease compounding
|
Combining
|
Thermal
|
Combine soaps & oils
|
Lube oil, fatty acid, alky metal
|
Lubricating grease
|
Polymerizing
|
Polymerize
|
Catalytic
|
Unite 2 or more olefins
|
Cracker olefins
|
High-octane naphtha, petrochemical stocks
|
CONVERSION PROCESSES--ALTERATION OR REARRANGEMENT
|
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Catalytic reforming
|
Alteration/
dehydration |
Catalytic
|
Upgrade low-octane naphtha
|
Coker/ hydro-cracker naphtha
|
High oct. Reformate/ aromatic
|
Isomerization
|
Rearrange
|
Catalytic
|
Convert straight chain to branch
|
Butane, pentane, hexane
|
Isobutane/ pentane/ hexane
|
TREATMENT PROCESSES
|
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*Amine treating
|
Treatment
|
Absorption
|
Remove acidic contaminants
|
Sour gas, HCs w/CO2 & H2S
|
Acid free gases & liquid HCs
|
Desalting
|
Dehydration
|
Absorption
|
Remove contaminants
|
Crude oil
|
Desalted crude oil
|
Drying & sweetening
|
Treatment
|
Abspt/ therm
|
Remove H2O & sulfur cmpds
|
Liq Hcs, LPG, alky feedstk
|
Sweet & dry hydrocarbons
|
*Furfural extraction
|
Solvent extr.
|
Absorption
|
Upgrade mid distillate & lubes
|
Cycle oils & lube feed-stocks
|
High quality diesel & lube oil
|
Hydrodesulfurization
|
Treatment
|
Catalytic
|
Remove sulfur, contaminants
|
High-sulfur residual/ gas oil
|
Desulfurized olefins
|
Hydrotreating
|
Hydrogenation
|
Catalytic
|
Remove impurities, saturate HC's
|
Residuals, cracked HC's
|
Cracker feed, distillate, lube
|
*Phenol extraction
|
Solvent extr.
|
Abspt/ therm
|
Improve visc. index, color
|
Lube oil base stocks
|
High quality lube oils
|
Solvent deasphalting
|
Treatment
|
Absorption
|
Remove asphalt
|
Vac. tower residual, propane
|
Heavy lube oil, asphalt
|
Solvent dewaxing
|
Treatment
|
Cool/ filter
|
Remove wax from lube stocks
|
Vac. tower lube oils
|
Dewaxed lube basestock
|
Solvent extraction
|
Solvent extr.
|
Abspt/ precip.
|
Separate unsat. oils
|
Gas oil, reformate, distillate
|
High-octane gasoline
|
Sweetening
|
Treatment
|
Catalytic
|
Remv H2S, convert mercaptan
|
Untreated distillate/gasoline
|
High-quality distillate/gasoline
|