Also known as:
A refinery is a plant that is comprised of a number of different processing units. Each of these plays a role in the overall process of converting crude oil into finished petroleum products. A typical refinery will have a dozen or more of these processing units. These fall into four broad categories:
Separation units - Some process units separate a hydrocarbon mixture into its components through distillation or extraction. The most common separation units are atmospheric distillation and vacuum distillation.
Conversion units - Conversion units take individual hydrocarbon streams and convert them to other hydrocarbons by changing their size and chemical structure. Examples are the coker, FCC and alkylation unit.
Treating units - A number of process improve a hydrocarbon stream by removing impurities and changing some chemical properties, but without changing the refinery's product yield. Good examples of this are the hydrotreaters
Supporting process units - This includes utilities and and other non-hydrocarbon processing units.
A typical large, complex refinery will have dozens of different process units. Some of the more common ones are:
Acid gas recovery (AGU, Amine unit) - removal of acid gases (CO2 and H2S) from refinery gas through amine absorption
Alkylation - Catalytic process for combining a light olefin (butylene and/or propylene) with isobutane to produce a high-octane gasoline blend stock (alkylate).
Alkylate splitter - fractionation unit that separates product alkylate from by-product LPG and excess iso-butane (which is recycled back to the alkylation feed)
ARDS (Atmospheric resid desulfurization) - catalytic process that removes sulfur from fuel oil or RCC feed by injecting hydrogen
Aromatics extraction (BTX) - Solvent extraction unit used to separate aromatics (benzene, toluene, xylenes) out of reformate. Part of the aromatics plant.
Atmospheric distillation (crude unit) - Distillation process for fractionating crude oil.
Benzene column - Distillation process for separating benzene from other aromatics (part of BTX complex)
C3 splitter - fractionation process that seprates propane from propylene
C4 isomerization - Catalytic process that converts n-butane to isobutane, typically to produce feed stock for alkyation
C5/C6 isomerization (Penex) - Catalytic process that converts C5 and C6 naphtha to higher octane branched chain isomers
Calciner - Thermal process that removes volatile hydrocarbons from petroleum coke
Coking - Thermal process that converts vacuum resid to lighter fractions and produces petroleum coke as a byproduct
Cumene production - catalytic process that converts benzene and propylene to cumene using an acid catalyst
Cyclohexane production - catalytic proces that converts benzene to cyclohexane through hydrogenation
DeButanizer - fractionation unit (distillation)that separates butane (and lighter components) from heavier components (pentane and heavier). Usually part of the gas plant, downstream from the deEthanizer
DeEthanizer - fractionation unit (using absorption) that separates ethane (and and residual methane) from propane and heavier. Usually part of the gas plant
Deheptanizer - fractionation unit (distillation) that separates isobutane from normal butane and heavier components. Usually part of the gas plant
DeIsobutanizer - fractionation unit (distillation)that separates isobutane from normal butane. Usually part of the gas plant
DeIsopentanizer - fractionation unit (distillation)that separates isopentane from normal pentane. Usually part of the gas plant
DePentanizer - fractionation unit (distillation)that separates pentanes from heavier components (C6 +).
DePropanizer - fractionation unit (distillation)that separates propane (and and residual methane) from butanes. Usually Usually part of the gas plant, downstream from the debutanizer
Desalter - - Extracts liquid salts from crude using water (as a solvent)
Distillate hydrotreater - Catalytic treating unit for diesel, removing sulfur and saturating double bonds
Dimersol (Dimer)- catalytic process that converts a light olefin (propylene or butylene) into a gasoline blendstock by combining two identical olefins with each other (dimerization) using an acid catalyst
ETBE - catalytic process that converts ethanol and isobutylene to a gasoline blendstock through esterification
Ethylbenzene - catalytic process that produces ethylbenzene by combining benzene and ethylene. A key step in the production of styrene.
FCC (Catalytic cracking unit) - Catalytic process used to convert VGO to lighter fractions
FCC gasoline hydrotreater - Catalytic hydrotreater for FCC gasoline, removing sulfur with minimal octane loss
Flare gas recovery - a unit that captures and treats waste gases in the flare system to recover valuable hydrocarbons
Hydrocracker - Catalytic process that converts heavy gasoils to low-sulfur middle distillates and lighter fractions by cracking while injecting hydtogen
Hydrodealkylation (HDA) - a process (typically catalytic to reduce reaction temperature) that converts toluene to benzene and methane through removal of an alkyl group and replacement with hydrogen.
Hydrogen production - Catalytic process that converts methane (and ater) to hydrogen (and byproduct CO2)
Hydrogen purification - Process for separating and concentrating hydrogen from a gas stream
Kerosene hydrotreater - Catalytic treater for kerosene, removing sulfur and raising smoke point
Merox - a mulit step process (extraction and catalytic oxidation) that removes mercaptans from LPG, naphtha, or kerosene
MTBE - catalytic process that converts methanol and isobutylene to a gasoline blendstock through esterification
Naphtha hydrotreater - Catalytic treater for naphtha, removing sulfur to produce feed for reformer and C5/C6 isomerization
Naphtha splitter - Distillation process to separate light naphtha (C5/C6) from heavy naphtha
Paraxylene unit - a separation unit that extracts paraxylene from a mixed xylene stream
Polymerization - catalytic process that converts a light olefins (propylene or butylene) into a gasoline blendstock by combining two olefins with each other (poymerization) using an acid catalyst
Reformate splitter - Distillation process to separate light and heavy fractions of reformate. Typically part of the BTX plant
Reformer - Catalytic process to convert heavy naphtha to an aromatics-rich naphtha (reformate) for gasoline blending or aromatics production (benzene, xylene)
Resid hydrocracker - Catalytic unit used to convert vacuum resid to low-sulfur, lighter fractions
SDA (Solvent deasphalting) - a separation process that extracts asphalt from a resid stream using a light paraffinic solvent such as propane or pentane. The other product is de-asphalted oil (DAO), similar to VGO.
Sulfur recovery unit (SRU or Claus) - a multistep process (partial combustion, catalytic reaction) to convert H2S gas to elemental sulfur
Tail gas recovery (TGU) - a multi-sep process for recovery residiual sulfur compounds in gas from the SRU (SO2 and COS) and converting back to H2S for recyle to the SRU
TAME - catalytic process (etherification) that produces the gasoline blendstock TAME by combining isoamylene (from the FCC) with methanol
Toluene disproportionation (TDP) - catalytic process (transalkylation) that converts toluene into a mixture of benzene and xylenes
Thermal cracker - thermal process (non catalytic) that converts VGO into lighter, cracked fractions. Similar to an FCC, but less effective.
Vacuum distillation - Distillation process to separate atmospheric bottoms into VGO and vacuum resid
VGO hydrotreater - Catalytic hydrotreater to reduce sulfur of VGO used as FCC feed stock
Visbreaking - Thermal process from reducing viscosity of vacuum resid