Common refinery process units

A typical large, complex refinery will have dozens of different process units.  Some of the more common ones are:

• Acid gas removal - 

• Alkylation - Catalytic process for combining light olefins (butylene and/or propylene) with isobutane to produce a high octane gasoline blend stock (alkylate).

• Alkylate splitter - 

• ARDS (Atmospheric resid desulfurization) - catalytic hydrotreating unit used to remove sulfur from fuel oil or RCC feed

• Aromatics extraction - Solvent extraction unit used to separate aromatics (benzene, toluene, xylenes) out of reformate.  Part of the aromatics plant.

• Asphalt plant - 

• Atmospheric distillation - Distillation process for fractionating crude oil. 

• Benzene column - Distillation process for separating benzene from other aromatics

• C3 splitter - 

• C4 isomerization - Catalytic process for converting n-butane to isobutane, typically to produce feed stock for alkyation

• C5/C6 isomerization - Catalytic process for converting straight chain C5/C6 naphtha to higher octane branched chain isomers

• Calciner - Thermal process for removing volatile hydrocarbons from petroleum coke

• Coking - Thermal process for converting vacuum resid to lighter fractions

• Cumene production

• Cyclohexane production

• DeButanizer

• DeEthanizer

• Deheptanizer

• DeHexanizer

• DeIsobutanizer

• DeIsoheptanizer

• DeIsohexanizer

• DeIsopentanizer

• DePentanizer

• DePropanizer

• 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

• ETBE

• Ethylbenzene

• FCC (Catalytic cracking unit) - used to convert VGO to lighter fractions

• FCC gasoline hydrotreater - Catalytic hydrotreater for FCC gasoline, removing sulfur with minimal octane loss

• Flare gas recovery

• Hydrocracker - Catalytic process for converting heavy gasoils to low-sulfur middle distillates and lighter fractions 

• Hydrodealkylation (HDA) - 

• Hydrogen production - Catalytic process for converting methane to hydrogen

• Hydrogen purification - Process for separating hydrogen from a gas stream

• IsoOctene

• Kerosene hydrotreater - Catalytic treater for kerosene, removing sulfur and raising smoke point

• MTBE

• 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

• Othoxylene rerun column - 

• Paraxylene unit - 

• Polymerization - 

• Reformate splitter - Distillation process to separate light and heavy fractions of reformate

• 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) - 

• Solvent fractionation

• Sulfur recovery unit (SRU) - 

• Tail gas recovery (TGU) - 

• TAME - 

• Toluene disproportionation (TDP) -  

• Thermal cracker - 

• Toluene column - 

• 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

• Xylene isomerization - 

• Xylene rerun column - 

• Xylene splitter -