Click on each item listed below to have its definition and/or the process diagram
Solution Resources
Refinery Process Diagram
General Process Diagram
Quick info
► Place the cursor over areas of the diagram to see more general info.
► Click on a box to see the technical profile for this area.
Separation Units: No two refineries are alike. Each refinery's uniqueness is formed by geographic location, crude availability, market demand and environmental regulations it must meet.
Sulfur Removal Units: Hydrotreating for the removal of sulfur and nitrogen is a very common process in the modern refinery.
With rare exceptions, intermediate products contain sulfur levels that exceed product specifications or catalyst limitations.
Conversion Units: A critical function of petroleum refining is the ability to match the yield from crude oil distillation with product demand from the marketplace.
Upgrading Units: Once the refined product slate has been cracked to match marketplace demand, the intermediate products must be processed to meet product specifications when blended.
Product Blending: Refined products are typically the result of blending several component streams or blend stocks.
Intermediate product qualities are measured and appropriate volumes are mixed into finished product storage using either batch operations or "in-line" blending methods.
Intermediate product qualities are measured and appropriate volumes are mixed into finished product storage using either batch operations or "in-line" blending methods.
Support Units: There are several processes that are not directly involved in the processing of hydrocarbons or form part of intermediate products yet play a critical supporting role.
Without them a petroleum refinery would not be able to exist.
Without them a petroleum refinery would not be able to exist.
The Gas Plant: Light ends are hydrocarbons boiling at the lowest temperatures including methane, ethane, propane, butanes, and pentanes, which contain from one to five carbon atoms. Light ends are fractionated in distillation towers and treated with amine contacting to remove hydrogen sulfide. The most abundant source of lights ends is cracking operations.
HDS Hydrocracker Sour Water
Sour Water Stripper: Stripping steam and wash water in various refining operations is condensed and removed from overhead condensate accumulators or product separators.
This water contains impurities most notably sulfur compounds and ammonia.
Hydrogen sulfide and ammonia is removed in the sour water stripper.
This water contains impurities most notably sulfur compounds and ammonia.
Hydrogen sulfide and ammonia is removed in the sour water stripper.
HDS Hydrocracker Sour Gas
Acid Gas Removal: Gases from various refining processes contain hydrogen sulfide.
Most hydrogen sulfide in a refinery is formed as a result of conversion processes such as hydrotreating, hydrocracking, cracking and coking operations.
It is common to remove this hydrogen sulfide and convert it to elemental sulfur.
Most hydrogen sulfide in a refinery is formed as a result of conversion processes such as hydrotreating, hydrocracking, cracking and coking operations.
It is common to remove this hydrogen sulfide and convert it to elemental sulfur.
Sulfur Recovery: The sulfur recovery process used in most refineries is a "Claus Unit".
In general, the Claus Unit involves combusting one-third of the hydrogen sulfide (H2S) into SO2 and, and then reacting the SO2 with the remaining H2S in the presence of cobalt-molybdenum catalyst to form elemental sulfur.
In general, the Claus Unit involves combusting one-third of the hydrogen sulfide (H2S) into SO2 and, and then reacting the SO2 with the remaining H2S in the presence of cobalt-molybdenum catalyst to form elemental sulfur.
Caustic Scrubbing: Once hydrogen sulfide has been removed from liquefied petroleum gases (LPG), mercaptan sulfur, remaining hydrogen sulfide, CO2, odor, HCL and other impurities can be removed using a caustic wash prior to further processing or sale.
The resulting spent caustic solution may be processed in a wet air oxidation (WAO) unit prior to release.
The resulting spent caustic solution may be processed in a wet air oxidation (WAO) unit prior to release.
Merox™ Treatment: Merox™ is a UOP process to sweeten products by extracting and/or converting mercaptan sulfur to less objectionable disulfides.
It is often used to treat products such as liquefied petroleum gases, naphtha, gasoline, kerosene, jet fuel and heating oils.
It is often used to treat products such as liquefied petroleum gases, naphtha, gasoline, kerosene, jet fuel and heating oils.
Crude Oil Storage: In almost all cases, crude oils have no inherent value without petroleum refining processes to convert them into marketable products.
Crude oil is a complex mixture of hydrocarbons that also contains sulfur, nitrogen, heavy metals and salts. Most of these contaminants must be removed in part or total during the refining process. The hydrocarbons that make up crude oil have boiling points from less than 60˚F to greater than 1200˚F (60-650˚C).
Desalter: All crude oil contains salt, predominantly chlorides.
Chloride salts can combine with water to form hydrochloric acid in atmospheric distillation unit overhead systems causing significant equipment damage and processing upsets.
Chlorides and other salts will also deposit on heat exchanger surfaces reducing energy efficiency and increasing equipment repairs and cleaning.
Chloride salts can combine with water to form hydrochloric acid in atmospheric distillation unit overhead systems causing significant equipment damage and processing upsets.
Chlorides and other salts will also deposit on heat exchanger surfaces reducing energy efficiency and increasing equipment repairs and cleaning.
Atmosheric Distillation Unit: Initial crude oil separation is accomplished by creating a temperature and pressure profile across a tower to enable different composition throughout the tower.
Naptha HDS: Most catalytic reforming catalysts contain platinum as the active material. Sulfur and nitrogen compounds will deactivate the catalyst and must be removed prior to catalytic reforming. The Naphtha HDS unit uses a cobalt-molybdenum catalyst to remove sulfur by converting it to hydrogen sulfide that is removed with unreacted hydrogen.
Kerosene HDS: Hydrotreating is a catalytic process to stabilize products and remove objectionable elements like sulfur, nitrogen and aromatics by reacting them with hydrogen.
Cobalt-molybdenum catalysts are used for desulphurization. When nitrogen removal is required in addition to sulfur, nickel-molybdenum catalysts are used.
In some instances, aromatics saturation is pursued during the hydrotreating process in order to improve diesel fuel performance.
Cobalt-molybdenum catalysts are used for desulphurization. When nitrogen removal is required in addition to sulfur, nickel-molybdenum catalysts are used.
In some instances, aromatics saturation is pursued during the hydrotreating process in order to improve diesel fuel performance.
Diesel HDS: Hydrotreating is a catalytic process to stabilize products and remove objectionable elements like sulfur, nitrogen and aromatics by reacting them with hydrogen.
Cobalt-molybdenum catalysts are used for desulphurization. When nitrogen removal is required in addition to sulfur, nickel-molybdenum catalysts are used.
In some instances, aromatics saturation is pursued during the hydrotreating process in order to improve diesel fuel performance.
Cobalt-molybdenum catalysts are used for desulphurization. When nitrogen removal is required in addition to sulfur, nickel-molybdenum catalysts are used.
In some instances, aromatics saturation is pursued during the hydrotreating process in order to improve diesel fuel performance.
Gas Oil HDS: Hydrotreating is a catalytic process to stabilize products and remove objectionable elements, particularly sulfur and nitrogen, by reacting them with hydrogen prior to feed to the FCC Unit.
Most hydrotreating reactions take place between 600-800˚F (315-425˚C) and at relatively high pressures up to 2000 psi (138 bar) depending on the level of reaction severity needed to meet product specification and the composition of the feedstock.
Most hydrotreating reactions take place between 600-800˚F (315-425˚C) and at relatively high pressures up to 2000 psi (138 bar) depending on the level of reaction severity needed to meet product specification and the composition of the feedstock.
Catalytic Reforming: Gasoline has a number of specifications that must be satisfied to provide high performance for today's motor vehicles.
Octane, however, is the most widely recognized specification. The octane number is generally reported as the average of Research Octane Number (RON) and Motor Octane Number (MON), (R+M)/2.
MON is the more severe test, so for a given fuel RON is always higher than MON.
Octane, however, is the most widely recognized specification. The octane number is generally reported as the average of Research Octane Number (RON) and Motor Octane Number (MON), (R+M)/2.
MON is the more severe test, so for a given fuel RON is always higher than MON.
Isomerization: Catalytic reforming has little effect on Light Straight Run gasoline (LSR), which is material in the C5 - 165˚F (74˚C) boiling range. This fraction is removed from reformer feed. Its octane number may be significantly improved by converting normal paraffins into their isomers in the Isom Unit.
Alkylation: Alkylation is a refining process that provides an economic outlet for very light olefins produced at the FCC and Coker. Alkylation is the opposite of cracking. The process takes small molecules and combines them into larger molecules with high octane and low vapor pressure characteristics.
Cat Gas HDS: Hydrotreating is a catalytic process to stabilize products and remove objectionable elements, particularly sulfur, by reacting them with hydrogen.
When the process is applied specifically for sulfur removal it is generally called hydrodesulfurization (HDS).
The HDS unit uses a cobalt-molybdenum catalyst to remove sulfur by converting it to hydrogen sulfide that is removed with unreacted hydrogen.
When the process is applied specifically for sulfur removal it is generally called hydrodesulfurization (HDS).
The HDS unit uses a cobalt-molybdenum catalyst to remove sulfur by converting it to hydrogen sulfide that is removed with unreacted hydrogen.
Fluid Catalytic Cracker (FCC): The FCC is considered by many as the heart of a modern petroleum refinery.
FCC is the tool refiners use to correct the imbalance between the market demand for lighter petroleum products and crude oil distillation that produces an excess of heavy, high boiling range products.
The FCC unit converts heavy gas oil into gasoline and diesel.
FCC is the tool refiners use to correct the imbalance between the market demand for lighter petroleum products and crude oil distillation that produces an excess of heavy, high boiling range products.
The FCC unit converts heavy gas oil into gasoline and diesel.
Hydrocracker: The Hydrocracker is similar to the FCC in that it is a catalytic process that cracks long chain gas oil molecules into smaller molecules that boil in the gasoline, jet fuel and diesel fuel range.
The fundamental difference is that cracking reactions take place in an extremely hydrogen rich atmosphere.
Two reactions occur. First carbon bonds are broken followed by attachment of hydrogen. Hydrocracker products are sulfur free and saturated.
Coker / Visbreaker: Coking and visbreaking are both thermal decomposition processes.
Coking is predominant in the United States while Visbreaking is mostly applied in Europe.
Coking is predominant in the United States while Visbreaking is mostly applied in Europe.
With the exception of the coking process, formation of coke in a petroleum refinery is undesirable because coke fouls equipment and reduces catalyst activity.
However, in the coking process, coke is intentionally produced as a byproduct of vacuum resid conversion from low value fuel and asphalt into higher value products.
Gasoline: Petroleum refineries produce a variety of components that are then used to blend refined products.
Product blending is a critical source of flexibility and profitability for refining operations.
Of great interest is the economic blending of gasoline.
Vaccum Distillation Units: Atmospheric resid is further fractionated in a Vacuum Distillation tower.
Products that exist as a liquid at atmospheric pressure will boil at a lower temperature when pressure is significantly reduced. Absolute operating pressure in a Vacuum Tower can be reduced to 20 mm of mercury or less (atmospheric pressure is 760 mm Hg).
In addition, superheated steam is injected with the feed and in the tower bottom to reduce hydrocarbon partial pressure to 10 mm of mercury or less.