45489448 Oil Gas Refining Basic

8/3/2019 45489448 Oil Gas Refining Basic

1/114

A Petroleum Prospecting Primer

Click on the numbers in the image below to learn about the tools Chevron uses in the quest for oiland natural gas.

People have used petroleum products for nearly 5,000 years. The Babylonians caulked theirships with asphalt, and the ancient Chinese lit their imperial palaces with natural gas. For theseearly users, finding petroleum was a matter of guesswork and good luck. People simply looked

for oil seeps and hoped the source was nearby.

Today, petroleum prospecting is considerably less random. The goal is to find a convergence ofthe geologic elements necessary to form an oil or gas field. These elements include a source rock(1)to generate hydrocarbons, a porous reservoir rock (2) to hold them and a structural trap (3)toprevent fluids and gas from leaking away. Traps tend to exist in predictable places - for example,along faults (4)andfolds (5)caused by movement of the Earth's crust or near subsurface saltdomes (6).

Finding these subterranean features requires a careful blend of science and art. For example,structural geology involves gathering and interpreting information from above ground to deducewhat lies underground. Geologists (7) obtain this information by examining exposed rocks or,when difficult terrain limits access, by examining images fromsatellites (8)and radar (9).

Subtle changes within the Earth's magnetic and gravitational fields also may signal the presenceof petroleum traps. To measure these changes, geophysicists use sensitive instruments calledgravity meters (10)or trail a magnetometer (11) from a plane in an aerial survey.

Seismic surveying involves sending sound waves underground and measuring how long it takessubsurface rocks to reflect them back to the surface. These waves are made by pounding theearth with a truck-mounted vibrator (12) or by exploding small charges on land or compressedairguns (13)at sea. As the waves are reflected back, they're collected by listening devices called
http://www.chevron.com/products/learning_center/primer/primer01.shtmlhttp://www.chevron.com/products/learning_center/primer/primer01.shtmlhttp://www.chevron.com/products/learning_center/primer/primer01.shtmlhttp://www.chevron.com/products/learning_center/primer/primer02-03.shtmlhttp://www.chevron.com/products/learning_center/primer/primer02-03.shtmlhttp://www.chevron.com/products/learning_center/primer/primer02-03.shtmlhttp://www.chevron.com/products/learning_center/primer/primer04.shtmlhttp://www.chevron.com/products/learning_center/primer/primer04.shtmlhttp://www.chevron.com/products/learning_center/primer/primer05-06.shtmlhttp://www.chevron.com/products/learning_center/primer/primer05-06.shtmlhttp://www.chevron.com/products/learning_center/primer/primer05-06.shtmlhttp://www.chevron.com/products/learning_center/primer/primer05-06.shtmlhttp://www.chevron.com/products/learning_center/primer/primer05-06.shtmlhttp://www.chevron.com/products/learning_center/primer/primer07.shtmlhttp://www.chevron.com/products/learning_center/primer/primer08.shtmlhttp://www.chevron.com/products/learning_center/primer/primer08.shtmlhttp://www.chevron.com/products/learning_center/primer/primer08.shtmlhttp://www.chevron.com/products/learning_center/primer/primer09-11.shtmlhttp://www.chevron.com/products/learning_center/primer/primer09-11.shtmlhttp://www.chevron.com/products/learning_center/primer/primer09-11.shtmlhttp://www.chevron.com/products/learning_center/primer/primer09-11.shtmlhttp://www.chevron.com/products/learning_center/primer/primer12-13.shtmlhttp://www.chevron.com/products/learning_center/primer/primer12-13.shtmlhttp://www.chevron.com/products/learning_center/primer/primer12-13.shtmlhttp://www.chevron.com/products/learning_center/primer/primer12-13.shtmlhttp://www.chevron.com/products/learning_center/primer/primer12-13.shtmlhttp://www.chevron.com/products/learning_center/primer/primer01.shtmlhttp://www.chevron.com/products/learning_center/primer/primer01.shtmlhttp://www.chevron.com/products/learning_center/primer/primer02-03.shtmlhttp://www.chevron.com/products/learning_center/primer/primer02-03.shtmlhttp://www.chevron.com/products/learning_center/primer/primer04.shtmlhttp://www.chevron.com/products/learning_center/primer/primer05-06.shtmlhttp://www.chevron.com/products/learning_center/primer/primer05-06.shtmlhttp://www.chevron.com/products/learning_center/primer/primer05-06.shtmlhttp://www.chevron.com/products/learning_center/primer/primer07.shtmlhttp://www.chevron.com/products/learning_center/primer/primer08.shtmlhttp://www.chevron.com/products/learning_center/primer/primer09-11.shtmlhttp://www.chevron.com/products/learning_center/primer/primer09-11.shtmlhttp://www.chevron.com/products/learning_center/primer/primer09-11.shtmlhttp://www.chevron.com/products/learning_center/primer/primer12-13.shtmlhttp://www.chevron.com/products/learning_center/primer/primer12-13.shtmlhttp://www.chevron.com/products/learning_center/primer/primer12-13.shtml


2/114

geophones (14) and processed by computers. Earth scientists use the data to create three-dimensional models of underground rocks.

Although sight and sound are the senses most frequently used in prospecting, smell also cancome into play. Asniffer (15)is a sort of high-tech "nose" that can detect traces of gaseoushydrocarbons escaping from subsurface accumulations.

Geologic and geophysical clues are enticing, but drilling- both on land (16) and offshore (17) - isthe only way to confirm an oil or gas field's existence. Once a well is drilled, downhole logginginstruments (18)yield data on the types of rock and fluid present.

In the petroleum industry, the average U.S. wildcat well (an exploratory well drilled a mile or morefrom existing production) has a one in 10 chance of striking hydrocarbons. A rank wildcat well,drilled in an unproven, frontier area, stands a one in 40 chance. Thus, although today'sprospectors have better tools than their ancient counterparts, good luck still is a factor in thesearch for petroleum.

What is crude oil?

Step right up. In this bottle is a remedy of wonderful efficacy. Its curative powers arecalculated to remove pain and alleviate human suffering and disease. Distilled 400 feet below theearth's surface, this remarkable liquid is Mother Nature's bounteous gift of healing. It is mypleasure - no, it is my duty - to bring this soothing restorative, this blessed ointment, this modern-day balm of Gilead to the public.

There were few takers of the 19th century elixir that came to be called "snake oil." It was one ofthe less successful uses of petroleum, but not the first to claim healing properties. AncientPersians, 10th century Sumatrans and pre-Columbian Indians all believed that crude oil hadmedicinal benefits. Marco Polo found it used in the Caspian Sea region to treat camels formange, and the first oil exported from Venezuela (in 1539) was intended as a gout treatment forthe Holy Roman Emperor Charles V.

The mysterious oil that sometimes seeped to the earth's surface had other uses as well. InMesopotamia around 4000 B.C., bitumen - a tarry crude - was used as caulking for ships, asetting for jewels and mosaics, and an adhesive to secure weapon handles. Egyptians used it forembalming, and the walls of Babylon and the famed pyramids were held together with it. TheRoman orator Cicero carried a crude-oil lamp. And, in North America, the Senecas and Iroquoisused crude oil for body paint and for ceremonial fires.

Crude oil - as petroleum directly out of the ground is called - is a remarkably varied substance,both in its use and composition. It can be a straw-colored liquid or tar-black solid. Red, green and
http://www.chevron.com/products/learning_center/primer/primer14.shtmlhttp://www.chevron.com/products/learning_center/primer/primer15.shtmlhttp://www.chevron.com/products/learning_center/primer/primer15.shtmlhttp://www.chevron.com/products/learning_center/primer/primer15.shtmlhttp://www.chevron.com/products/learning_center/primer/primer16.shtmlhttp://www.chevron.com/products/learning_center/primer/primer17.shtmlhttp://www.chevron.com/products/learning_center/primer/primer18.shtmlhttp://www.chevron.com/products/learning_center/primer/primer18.shtmlhttp://www.chevron.com/products/learning_center/primer/primer18.shtmlhttp://www.chevron.com/products/learning_center/primer/primer14.shtmlhttp://www.chevron.com/products/learning_center/primer/primer15.shtmlhttp://www.chevron.com/products/learning_center/primer/primer16.shtmlhttp://www.chevron.com/products/learning_center/primer/primer17.shtmlhttp://www.chevron.com/products/learning_center/primer/primer18.shtmlhttp://www.chevron.com/products/learning_center/primer/primer18.shtml


3/114


4/114

boil below atmospheric temperature. Crude oil components used to make gasoline boil in therange of 55 to 400 degrees Fahrenheit. Those used for jet fuel boil in the range of 300 to 550degrees, and those for diesel, at about 700 degrees.

There are three essentials in the creation of a crude oil field:

First, a "source rock" whose geologic history allowed the formation of crude oil. Thisusually is a fine-grained shale rich in organic matter.

Second, migration of the oil from the source rock to a "reservoir rock," usually asandstone or limestone that's thick and porous enough to hold a sizable accumulation ofoil. A reservoir rock that's only a few feet thick may be commercially producible if it's at arelatively shallow depth and near other fields. However, to warrant the cost of producingin more challenging regions (the Arctic North Slope, for example) the reservoir may haveto be several hundred feet thick.

Third, entrapment. The earth is constantly creating irregular geologic structures throughboth sudden and gradual movements - earthquakes, volcanic eruptions and erosioncaused by wind and water. Uplifted rock, for example, can result in domelike structures orarched folds called anticlines. These often serve as receptacles for hydrocarbons. Theprobability of discovering oil is greatest when such structures are formed near a source

rock. In addition, an overlying, impermeable rock must be present to seal themigrating oil in the structure.

The oldest oil-bearing rocks date back more than 600 million years; the youngest, about 1million. However, most oil fields have been found in rocks between 10 million and 270million years old.

Subsurface temperature, which increases with depth, is a critical factor in the creation ofoil. Petroleum hydrocarbons rarely are formed at temperatures less than 150 degreesFahrenheit and generally are carbonized and destroyed at temperatures greater than 500

degrees. Most hydrocarbons are found at "moderate" temperatures ranging from 225 to 350degrees.

It is the particular crude oil's geologic history that is most important in determining itscharacteristics. Some crudes from Louisiana and Nigeria are similar because both were formed insimilar marine deposits. In parts of the Far East, crude oil generally is waxy, black or brown, andlow in sulfur. It is similar to crudes found in central Africa because both were formed fromnonmarine sources. In the Middle East, crude oil is black but less waxy and higher in sulfur.Crude oil from Western Australia can be a light, honey-colored liquid, while that from the NorthSea typically is a waxy, greenish-black liquid. Many kinds of crudes are found in the United Statesbecause there is great variety in the geologic history of its different regions.

Crude oil is a surprisingly abundant commodity. The world has produced some 650 billion barrelsof oil, but another trillion barrels of proved reserves have yet to be produced. An additional 10trillion barrels of oil resources await development, assuming the price of oil someday justifiesproduction. These resources include bitumen, shale oil and oil in existing fields that might be

produced through enhanced recovery methods.

Talk of crude oil oozes with superlatives. Not only was crude oil the basis of the world's firsttrillion-dollar industry, it also is the largest item in the balance of payments and exchangesbetween nations. And it employs most of the world's commercial shipping tonnage.

Crude oil may not be the panacea that snake oil claimed to be. But for 20th century industrializednations, it has proved to be more than good medicine.


5/114

What is a Refinery?

Inside a maze of silver towers and pipes is a fascinating factory that changes hydrocarbonmolecules to make gasoline.

A refinery is a factory. Just as a paper mill turns lumber into legal pads or a glassworks turnssilica into stemware, a refinery takes a raw material--crude oil--and transforms it into gasoline andhundreds of other useful products.

A typical large refinery costs billions of dollars to build and millions more to maintain and upgrade.It runs around the clock 365 days a year, employs between 1,000 and 2,000 people and occupies

as much land as several hundred football fields. It's so big and sprawling, in fact, that workers ridebicycles from one station to another.

Chevron has five gasoline-producing "Factories" in the United States and another in Burnaby,British Columbia. Chevron has refining capacities worldwide of over two million barrels per day.

These world class operations had surprisingly humble origins. In 1876, company pioneers usedwagons and mules to haul two primitive stills to a spot near Pico Canyon, Calif., the site ofCalifornia's first producing oil wells. The stills, each about the size of a garage, were used to heatoil at the prodigious rate of 25 to 40 barrels a day. This "oil boiling" produced kerosene,lubricants, waxes and gasoline--a clear, lightweight liquid that generally was discarded as auseless byproduct. (Read more about Chevron's first refineries in the History section.)

Gasoline's lowly status rose quickly after 1892, when Charles Duryea built the first U.S. gas-powered automobile. From then on, the light stuff from crude oil became the right stuff.

Today, some refineries can turn more than half of every 42-gallon barrel of crude oil into gasoline.That's a remarkable technological improvement from 70 years ago, when only 11 gallons ofgasoline could be produced. How does this transformation take place? Essentially, refiningbreaks crude oil down into its various components, which then are selectively reconfigured intonew products.
http://www.chevron.com/products/learning_center/history/time/1876-1911/Default.asphttp://www.chevron.com/products/learning_center/history/time/1876-1911/Default.asphttp://www.chevron.com/products/learning_center/history/time/1876-1911/Default.asp


6/114

This process takes place inside a maze of hardware that one observer has likened to "ametal spaghetti factory." Employees regulate refinery operations from within highlyautomated control rooms. Because so much activity happens out of sight, refineries aresurprisingly quiet places. The only sound most visitors hear is the constant, low hum ofheavy equipment.

The complexity of this equipment varies from one refinery to the next. In general, themore sophisticated a refinery, the better its ability to upgrade crude oil into high-value products.Whether simple or complex, however, all refineries perform three basic steps: separation,conversion and treatment.

Separation: heavy on the bottom, light on the top

Modern separation--which is not terribly different from the "cooking" methods used at the PicoCanyon stills--involves piping oil through hot furnaces. The resulting liquids and vapors aredischarged intodistillation towers,the tall, narrow columns that give refineries their distinctiveskylines.

Inside the towers, the liquids and vapors separate into components orfractions according toweight and boiling point. The lightest fractions, including gasoline and liquid petroleum gas (LPG),vaporize and rise to the top of the tower, where they condense back to liquids. Medium weightliquids, including kerosene and diesel oil distillates, stay in the middle. Heavier liquids, called gasoils, separate lower down, while the heaviest fractions with the highest boiling points settle at thebottom. These tarlike fractions, called residuum, are literally the "bottom of the barrel."

The fractions now are ready for piping to the next station orplant within the refinery. Somecomponents require relatively little additional processing to become asphalt base or jet fuel.However, most molecules that are destined to become high-value products require much moreprocessing.

Conversion: cracking and rearranging molecules toadd value

This is where refining's fanciest footwork takes place--where fractions from the distillation towersare transformed into streams (intermediate components) that eventually become finishedproducts. This also is where a refinery makes money, because only through conversion can mostlow-value fractions become gasoline.

The most widely used conversion method is called cracking because it uses heat and pressureto "crack" heavy hydrocarbon molecules into lighter ones. A cracking unit consists of one or moretall, thick-walled, bullet-shaped reactors and a network of furnaces, heat exchangers and othervessels.

Fluid catalytic cracking, or "cat cracking," is the basic gasoline-making process. Using intenseheat (about 1,000 degrees Fahrenheit), low pressure and a powdered catalyst (a substance thataccelerates chemical reactions), the cat cracker can convert most relatively heavy fractions intosmaller gasoline molecules.
http://www.chevron.com/products/learning_center/refinery/chart.shtmlhttp://www.chevron.com/products/learning_center/refinery/chart.shtmlhttp://www.chevron.com/products/learning_center/refinery/chart.shtmlhttp://www.chevron.com/products/learning_center/refinery/chart.shtml


7/114

Hydrocracking applies the same principles but uses a different catalyst, slightlylower temperatures, much greater pressure and hydrogen to obtain chemicalreactions. Although not all refineries employ hydrocracking, Chevron is anindustry leader in using this technology to cost-effectively convert medium- toheavyweight gas oils into high-value streams. The company's patentedhydrocracking process, which takes place in the Isocrackerunit, produces mostlygasoline and jet fuel.

Some Chevron refineries also have cokers, which use heat and moderatepressure to turn residuum into lighter products and a hard, coallike substance

that is used as an industrial fuel. Cokers are among the more peculiar-looking refinery structures.They resemble a series of giant drums with metal derricks on top.

Cracking and coking are not the only forms of conversion. Other refinery processes, instead ofsplitting molecules, rearrange them to add value. Alkylation, for example, makes gasolinecomponents by combining some of the gaseous byproducts of cracking. The process, whichessentially is cracking in reverse, takes place in a series of large, horizontal vessels and tall,skinny towers that loom above other refinery structures.

Reforming uses heat, moderate pressure and catalysts to turn naphtha, a light, relatively low-value fraction, into high-octane gasoline components. Chevron's patented reforming process iscalled Rheniforming for the rheniumplatinum catalyst used.

Treatment: the finishing touch

Back when Chevron's founders boiled crude oil to get kerosene, they didn't have to worry aboutcustomer specifications or government standards. Today, however, a major portion of refininginvolves blending, purifying, fine-tuning and otherwise improving products to meet theserequirements.

To make Chevron gasoline, refinery technicians carefully combine a variety of streams from theprocessing units. Among the variables that determine the blend are octane level, vapor pressureratings and special considerations, such as whether the gasoline will be used at high altitudes.Technicians also add Techron, Chevron's patented performance additive, and dyes thatdistinguish the various grades of fuel.

Refining has come a long way since the oil boiling days of Pico Canyon. By the time a gallon ofgasoline is pumped into a car's tank, it contains more than 200 hydrocarbons and additives. Allthat changing of molecules pays off in a product that ensures smooth, high-performance driving.
http://www.chevron.com/products/prodserv/fuels/techrongas/http://www.chevron.com/products/prodserv/fuels/techrongas/http://www.chevron.com/products/prodserv/fuels/techrongas/


8/114

A quick lesson in refinery economics

The ultimate operating variable is, of course, the price of crude oil. Crude oil quality is another keyvariable. Heavy, high-sulfur crudes can cost up to one-third less than lighter, better crudes.However, because high-sulfur crudes require more processing, refineries that buy primarily cheapcrudes incur more fixed expenses for equipment and labor.

Processing high-sulfur crudes also requires greater expenditures for energy. In fact, energyaccounts for roughly half the cost of running a refinery, which is the main reason Chevron hascogeneration plants at most of its facilities. Cogeneration uses gases from refinery processingunits to generate electricity and steam.

Refinery location is yet another variable. The closer a refinery is to both crude oil sources and ahigh demand market, the lower transportation costs are. Chevron's large and modern refinery inPascagoula, Miss., on the other hand, is not as close to major gasoline-buying markets. Thus,Chevron must factor in the added cost of getting Pascagoula's products to market. Nevertheless,the refinery has posted excellent profits, largely because it is well-equipped to run some of theheaviest, cheapest crudes in the world.


9/114

Running a refinery is never simple, and Chevron works hardto keep its facilities safe, flexible and compatible with theenvironment

What is aRefinery?

A Lesson in How to Make Gasoline

An oil refinery is a more than just a complicated maze of steel towers andpipes. It is actually a factory that takes crude oil and turns it into gasolineand hundreds of other products necessary for our modern society tofunction.

A typical refinery these days costs billions of dollars ($$$) to build, andmillions more just to maintain and upgrade. Large refineries are complexoperations that run 365 days a year, employ as many as 2,000 people, andmay occupy as much land as several hundred football fields. Some are so bigand sprawling that workers need to ride bicycles just to get from one part

of the refinery complex to another.

Yet refineries of today had surprisingly humble origins. For example, KernCounty pioneers in the 1860's used mule-drawn wagons to haul a primitivestill to a spot near the modern intersection of Twissleman Road and Highway33 to erect the Buena Vista refinery. This pioneer operation boiled a fewbarrels a day of tarry oil, dipped by hand from shallow shafts thatrepresented Kern County's first oil wells, to produce kerosene for lamps,lubricants for wagon wheels, waxes for candles, and gasoline--a clear,

lightweight liquid that was usually thrown away as a useless byproduct.

The lowly status of gasoline changed dramatically, when Charles Duryea in1892 built the first gas-powered automobile in the United States. Within

just a few short years cars became engrained our society, and the lightstuff from crude oil became the right stuff. Today, refineries turn morethan half of every 42-gallon barrel of crude oil into gasoline. This is a


10/114

remarkable advance from 70 years ago when each barrel of crude yieldedonly 11 gallons of gasoline.

How does this remarkable transformation take place? Actually, there are

three basic steps common to all refining operations, whether big or small,simple or complex. First, the separation process separates crude oil intovarious chemical components. Next, the conversion process goes a stepfurther by breaking these chemicals down into molecules calledhydrocarbons. Lastly, the treatment process combines and transformshydrocarbon molecules, and other chemicals called additives, to create ahost of new products.

Separation: Heavy on thebottom, Light on the top

Separation starts by pumping crudeoil into pipes running through hotfurnaces and heating the oil tovaporize it. The resulting vapors andliquids are discharged into distillationtowers, the tall, narrow columns that

give refineries their distinctiveskylines. The process is basically thesame used at the old Buena Vista stillin the early days of the Kern County oil industry.

Inside the towers, the liquids and vapors separate into components orfractions according to their density and boiling point. The lightest fractions,including gasoline and liquid petroleum gas (LPG), vaporize and rise to the topof the tower, where they condense back to liquids. Medium-weight liquids,

including kerosene and diesel oil, stay in the middle. Heavier liquids, calledgas oils, separate lower down. The heaviest fractions with the highest boilingpoints settle at the bottom. These tar-like fractions, called residuum, areliterally the "bottom of the barrel."

The various fractions are then piped to different stations or plants withinthe refinery. Some fractions require relatively little additional processing to
http://www.sjgs.com/refinery.html#separation%23separationhttp://www.sjgs.com/refinery.html#conversion%23conversionhttp://www.sjgs.com/refinery.html#treatment%23treatmenthttp://www.sjgs.com/distillation.gifhttp://www.sjgs.com/distillation.gifhttp://www.sjgs.com/refinery.html#separation%23separationhttp://www.sjgs.com/refinery.html#conversion%23conversionhttp://www.sjgs.com/refinery.html#treatment%23treatmenthttp://www.sjgs.com/distillation.gifhttp://www.sjgs.com/distillation.gif


11/114


12/114

refinery structures. They resemble a series of giant drums with metalderricks on top.

Cracking and coking are not the only forms of conversion. Other refinery

processes, instead of splitting molecules, rearrange them to add value.Alkylation, for example, makes gasoline components by combining some ofthe gaseous byproducts of cracking. The process, which essentially iscracking in reverse, takes place in a series of large, horizontal vessels andtall, skinny towers that loom above other refinery structures.

Reforming uses heat, moderate pressure, and catalysts to turn naphtha, alight, relatively low-value fraction of the oil, into high-octane gasoline.

Treatment: Adding the finishing touches

Treament is the final step before tanker trucks and railroad cars head outof the refinery to deliver gasoline to our local gas station. Back whenworkers at the Buena Vista refinery boiled crude oil to get kerosene, theydidn't worry about customer specifications or government standards. Todayis diffrerent, and a major part of modern refining involves blending,purifying, fine-tuning and otherwise improving products to meet theserequirements.

To make gasoline, refinery technicians carefully combine a variety ofstreams from the processing units. Among the variables that determine theblend are octane level, vapor pressure ratings, and other specialconsiderations, such as whether the gasoline will be used at high altitudes.Technicians also add patented performance additives, and dyes todistinguish the various grades of fuel.

Refining has come a long way since the days of the Buena Vista refining still.

By the time a gallon of gas is pumped into a car, it contains more than 200hydrocarbons and additives. All that changing of molecules pays off in aproduct that ensures smooth, high-performance driving.


13/114

Contents

[hide]

1 Operation

2 Products of oil refineries

3 Safety and environmental concerns

4 Common process units found in a refinery

5 Specialty end products
http://toggletoc%28%29/http://en.wikipedia.org/wiki/Oil_refinery#Operation%23Operationhttp://en.wikipedia.org/wiki/Oil_refinery#Products_of_oil_refineries%23Products_of_oil_refinerieshttp://en.wikipedia.org/wiki/Oil_refinery#Safety_and_environmental_concerns%23Safety_and_environmental_concernshttp://en.wikipedia.org/wiki/Oil_refinery#Common_process_units_found_in_a_refinery%23Common_process_units_found_in_a_refineryhttp://en.wikipedia.org/wiki/Oil_refinery#Specialty_end_products%23Specialty_end_productshttp://toggletoc%28%29/http://en.wikipedia.org/wiki/Oil_refinery#Operation%23Operationhttp://en.wikipedia.org/wiki/Oil_refinery#Products_of_oil_refineries%23Products_of_oil_refinerieshttp://en.wikipedia.org/wiki/Oil_refinery#Safety_and_environmental_concerns%23Safety_and_environmental_concernshttp://en.wikipedia.org/wiki/Oil_refinery#Common_process_units_found_in_a_refinery%23Common_process_units_found_in_a_refineryhttp://en.wikipedia.org/wiki/Oil_refinery#Specialty_end_products%23Specialty_end_products


14/114

6 Co-plant siting

7 History

8 See also

9 References

10 External links

An oil refinery is an industrialprocessplant wherecrude oil is processed and refinedinto more usefulpetroleum products, such as gasoline, dieselfuel, asphalt base, heating

oil, kerosene, and liquefied petroleum gas.

Contents

[show]

[edit] Operation

Crude oil is separated into fractions by fractional distillation. The fractionating column is

cooler at the top than at the bottom so the vapours can condense more easily whilemoving up the column. The heavier fractions that emerge from the bottom of the

fractionating column are often broken up (cracked) to make more useful products.

Raw oil or unprocessed ("crude") oil is not very useful in the form it comes in out of the

ground. Although "light, sweet" (low viscosity, low sulfur) oil has been used directly as a
http://en.wikipedia.org/wiki/Oil_refinery#Co-plant_siting%23Co-plant_sitinghttp://en.wikipedia.org/wiki/Oil_refinery#History%23Historyhttp://en.wikipedia.org/wiki/Oil_refinery#See_also%23See_alsohttp://en.wikipedia.org/wiki/Oil_refinery#References%23Referenceshttp://en.wikipedia.org/wiki/Oil_refinery#External_links%23External_linkshttp://en.wikipedia.org/wiki/Processhttp://en.wikipedia.org/wiki/Processhttp://en.wikipedia.org/wiki/Crude_oilhttp://en.wikipedia.org/wiki/Crude_oilhttp://en.wikipedia.org/wiki/Petroleum_productshttp://en.wikipedia.org/wiki/Gasolinehttp://en.wikipedia.org/wiki/Dieselhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Kerosenehttp://en.wikipedia.org/wiki/Kerosenehttp://toggletoc%28%29/http://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=1http://en.wikipedia.org/wiki/Fractional_distillationhttp://en.wikipedia.org/wiki/Fractional_distillationhttp://en.wikipedia.org/wiki/Cracking_(chemistry)http://en.wikipedia.org/wiki/Image:Crude_Oil_Distillation.pnghttp://en.wikipedia.org/wiki/Image:Crude_Oil_Distillation.pnghttp://en.wikipedia.org/wiki/Oil_refinery#Co-plant_siting%23Co-plant_sitinghttp://en.wikipedia.org/wiki/Oil_refinery#History%23Historyhttp://en.wikipedia.org/wiki/Oil_refinery#See_also%23See_alsohttp://en.wikipedia.org/wiki/Oil_refinery#References%23Referenceshttp://en.wikipedia.org/wiki/Oil_refinery#External_links%23External_linkshttp://en.wikipedia.org/wiki/Processhttp://en.wikipedia.org/wiki/Crude_oilhttp://en.wikipedia.org/wiki/Petroleum_productshttp://en.wikipedia.org/wiki/Gasolinehttp://en.wikipedia.org/wiki/Dieselhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Kerosenehttp://toggletoc%28%29/http://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=1http://en.wikipedia.org/wiki/Fractional_distillationhttp://en.wikipedia.org/wiki/Cracking_(chemistry)


15/114

burner fuel for steam vessel propulsion, the lighter elements form explosive vapors in the

fuel tanks and so it is quite dangerous, especially so in warships. For this and many other

uses, the oil needs to be separated into parts and refined before use infuels andlubricants, and before some of the byproducts could be used in petrochemical processes

to form materials such asplastics, and foams.Petroleumfossil fuels are used in ship,

automobile andaircraftengines. These differenthydrocarbons have differentboilingpoints, which means they can be separated by distillation. Since the lighter liquid

elements are in great demand for use in internal combustion engines, a modern refinery

will convert heavy hydrocarbons and lighter gaseous elements into these higher valueproducts using complex and energy intensive processes.

Oil can be used in so many various ways because it contains hydrocarbons of varying

molecular masses, forms and lengths such asparaffins,aromatics,naphthenes(or

cycloalkanes), alkenes, dienes, and alkynes. Hydrocarbons are molecules of varyinglength and complexity made of onlyhydrogen and carbonatoms. Their various structures

give them their differing properties and thereby uses. The trick in the oil refinement

process is separating and purifying these.

Once separated and purified of any contaminants and impurities, the fuel or lubricant canbe sold without any further processing. Smaller molecules such as isobutaneand

propylene orbutylenes can be recombined to meet specificoctane requirements of fuels

by processes such as alkylation or less commonly, dimerization. Octane grade of gasolinecan also be improved by catalytic reforming, which strips hydrogen out of hydrocarbons

to produce aromatics, which have much higheroctane ratings. Intermediate products such

as gasoils can even be reprocessed to break a heavy, long-chained oil into a lighter short-

chained one, by various forms ofcrackingsuch as Fluid Catalytic Cracking, ThermalCracking, and Hydrocracking. The final step in gasoline production is the blending of

fuels with different octane ratings, vapor pressures, and other properties to meet productspecifications.

[edit] Products of oil refineries

Asphalt

Diesel fuel

Fuel oils

Gasoline

Kerosene

Liquid petroleum gas (LPG)

Lubricating oils Paraffin wax

Tar

[edit] Safety and environmental concerns
http://en.wikipedia.org/wiki/Warshipshttp://en.wikipedia.org/wiki/Fuelshttp://en.wikipedia.org/wiki/Fuelshttp://en.wikipedia.org/wiki/Lubricantshttp://en.wikipedia.org/wiki/Lubricantshttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Foamhttp://en.wikipedia.org/wiki/Petroleumhttp://en.wikipedia.org/wiki/Petroleumhttp://en.wikipedia.org/wiki/Fossil_fuelshttp://en.wikipedia.org/wiki/Shiphttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Enginehttp://en.wikipedia.org/wiki/Hydrocarbonshttp://en.wikipedia.org/wiki/Hydrocarbonshttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Distillationhttp://en.wikipedia.org/wiki/Hydrocarbonshttp://en.wikipedia.org/wiki/Molecular_masshttp://en.wikipedia.org/wiki/Paraffinhttp://en.wikipedia.org/wiki/Aromatichttp://en.wikipedia.org/wiki/Aromatichttp://en.wikipedia.org/wiki/Aromatichttp://en.wikipedia.org/wiki/Naphthenehttp://en.wikipedia.org/wiki/Naphthenehttp://en.wikipedia.org/wiki/Cycloalkanehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Dienehttp://en.wikipedia.org/wiki/Alkynehttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Isobutanehttp://en.wikipedia.org/wiki/Isobutanehttp://en.wikipedia.org/wiki/Propylenehttp://en.wikipedia.org/wiki/Butylenehttp://en.wikipedia.org/wiki/Octanehttp://en.wikipedia.org/wiki/Octanehttp://en.wikipedia.org/wiki/Alkylationhttp://en.wikipedia.org/wiki/Dimerizationhttp://en.wikipedia.org/wiki/Catalytic_reforminghttp://en.wikipedia.org/wiki/Aromaticshttp://en.wikipedia.org/wiki/Petrol#Octane_ratinghttp://en.wikipedia.org/wiki/Gasoilhttp://en.wikipedia.org/wiki/Cracking_(chemistry)http://en.wikipedia.org/wiki/Cracking_(chemistry)http://en.wikipedia.org/wiki/Vapor_pressurehttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=2http://en.wikipedia.org/wiki/Asphalthttp://en.wikipedia.org/wiki/Dieselhttp://en.wikipedia.org/wiki/Fuel_oilhttp://en.wikipedia.org/wiki/Gasolinehttp://en.wikipedia.org/wiki/Kerosenehttp://en.wikipedia.org/wiki/Liquid_petroleum_gashttp://en.wikipedia.org/wiki/Lubricanthttp://en.wikipedia.org/wiki/Paraffin_waxhttp://en.wikipedia.org/wiki/Tarhttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=3http://en.wikipedia.org/wiki/Warshipshttp://en.wikipedia.org/wiki/Fuelshttp://en.wikipedia.org/wiki/Lubricantshttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Foamhttp://en.wikipedia.org/wiki/Petroleumhttp://en.wikipedia.org/wiki/Fossil_fuelshttp://en.wikipedia.org/wiki/Shiphttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Aircrafthttp://en.wikipedia.org/wiki/Enginehttp://en.wikipedia.org/wiki/Hydrocarbonshttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Boiling_pointhttp://en.wikipedia.org/wiki/Distillationhttp://en.wikipedia.org/wiki/Hydrocarbonshttp://en.wikipedia.org/wiki/Molecular_masshttp://en.wikipedia.org/wiki/Paraffinhttp://en.wikipedia.org/wiki/Aromatichttp://en.wikipedia.org/wiki/Naphthenehttp://en.wikipedia.org/wiki/Cycloalkanehttp://en.wikipedia.org/wiki/Alkenehttp://en.wikipedia.org/wiki/Dienehttp://en.wikipedia.org/wiki/Alkynehttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Isobutanehttp://en.wikipedia.org/wiki/Propylenehttp://en.wikipedia.org/wiki/Butylenehttp://en.wikipedia.org/wiki/Octanehttp://en.wikipedia.org/wiki/Alkylationhttp://en.wikipedia.org/wiki/Dimerizationhttp://en.wikipedia.org/wiki/Catalytic_reforminghttp://en.wikipedia.org/wiki/Aromaticshttp://en.wikipedia.org/wiki/Petrol#Octane_ratinghttp://en.wikipedia.org/wiki/Gasoilhttp://en.wikipedia.org/wiki/Cracking_(chemistry)http://en.wikipedia.org/wiki/Vapor_pressurehttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=2http://en.wikipedia.org/wiki/Asphalthttp://en.wikipedia.org/wiki/Dieselhttp://en.wikipedia.org/wiki/Fuel_oilhttp://en.wikipedia.org/wiki/Gasolinehttp://en.wikipedia.org/wiki/Kerosenehttp://en.wikipedia.org/wiki/Liquid_petroleum_gashttp://en.wikipedia.org/wiki/Lubricanthttp://en.wikipedia.org/wiki/Paraffin_waxhttp://en.wikipedia.org/wiki/Tarhttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=3


16/114

MiRO refinery at Karlsruhe

Oil refineries are typically large sprawlingindustrial complexes with extensivepipingrunning throughout. The refining process releases numerous different chemicals into the

atmosphere; consequently, there are substantial air pollution emissions[1] and a notable

odornormally accompanies the presence of a refinery. Aside from air pollution impactsthere are also wastewater concerns,[2] upset risks of fire and explosion, and both

occupational noise and environmental noise health effects.

The public has demanded that many governments place restrictions on contaminants that

refineries release, and most refineries have installed the equipment needed to complywith the requirements of the pertinent environmental protection regulatory agencies. In

the United States, there is strong pressure to prevent the development of new refineries,

and no major refinery has been built in the country since Marathon'sGaryville facility in

1976. However, many existing refineries have been expanded during that time.Environmental restrictions and pressure to prevent construction of new refineries have

also contributed to rising fuel prices in the United States[citation needed].

Environmental and safety concerns mean that oil refineries are sometimes located somedistance away from major urban areas. Nevertheless, there are many instances where

refinery operations are close to populated areas and pose health risks such as in Tenerife,

Spain [3], which is sited in a densely-populated city center and next to the only two major

evacuation routes in and out of the city. In California'sContra Costa County and SolanoCounty, a shoreline necklace of refineries and associated chemical plants are adjacent to

urban areas in Richmond,Martinez, California,Pacheco,Concord,Pittsburg, Vallejoand

Benicia, with occasional accidental events that require "shelter in place" orders to the

adjacent populations.

[edit] Common process units found in a refinery

DesalterUnit (washes out salt from the crude oil before it goes into the

atmospheric distillation unit)

Atmospheric Distillation Unit (distills crude oil into fractions)
http://en.wikipedia.org/wiki/Karlsruhehttp://en.wikipedia.org/wiki/Industryhttp://en.wikipedia.org/wiki/Industryhttp://en.wikipedia.org/wiki/Pipinghttp://en.wikipedia.org/wiki/Earth's_atmospherehttp://en.wikipedia.org/wiki/Air_pollutionhttp://en.wikipedia.org/wiki/Oil_refinery#_note-0%23_note-0http://en.wikipedia.org/wiki/Odorhttp://en.wikipedia.org/wiki/Oil_refinery#_note-1%23_note-1http://en.wikipedia.org/wiki/Oil_refinery#_note-1%23_note-1http://en.wikipedia.org/w/index.php?title=Occupational_noise&action=edithttp://en.wikipedia.org/wiki/Noise_health_effectshttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Marathon_Petroleum_Companyhttp://en.wikipedia.org/wiki/Garyville%2C_Louisianahttp://en.wikipedia.org/wiki/1976http://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Tenerifehttp://en.wikipedia.org/wiki/Oil_refinery#_note-2%23_note-2http://en.wikipedia.org/wiki/Californiahttp://en.wikipedia.org/wiki/Contra_Costa_Countyhttp://en.wikipedia.org/wiki/Contra_Costa_Countyhttp://en.wikipedia.org/wiki/Solano_Countyhttp://en.wikipedia.org/wiki/Solano_Countyhttp://en.wikipedia.org/wiki/Richmond%2C_Californiahttp://en.wikipedia.org/wiki/Richmond%2C_Californiahttp://en.wikipedia.org/wiki/Martinez%2C_Californiahttp://en.wikipedia.org/wiki/Martinez%2C_Californiahttp://en.wikipedia.org/wiki/Pacheco%2C_Californiahttp://en.wikipedia.org/wiki/Pacheco%2C_Californiahttp://en.wikipedia.org/wiki/Concord%2C_Californiahttp://en.wikipedia.org/wiki/Pittsburg%2C_Californiahttp://en.wikipedia.org/wiki/Pittsburg%2C_Californiahttp://en.wikipedia.org/wiki/Vallejo%2C_Californiahttp://en.wikipedia.org/wiki/Vallejo%2C_Californiahttp://en.wikipedia.org/wiki/Benicia%2C_Californiahttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=4http://en.wikipedia.org/wiki/Desalterhttp://en.wikipedia.org/wiki/Image:MiRO1.jpghttp://en.wikipedia.org/wiki/Image:MiRO1.jpghttp://en.wikipedia.org/wiki/Karlsruhehttp://en.wikipedia.org/wiki/Industryhttp://en.wikipedia.org/wiki/Pipinghttp://en.wikipedia.org/wiki/Earth's_atmospherehttp://en.wikipedia.org/wiki/Air_pollutionhttp://en.wikipedia.org/wiki/Oil_refinery#_note-0%23_note-0http://en.wikipedia.org/wiki/Odorhttp://en.wikipedia.org/wiki/Oil_refinery#_note-1%23_note-1http://en.wikipedia.org/w/index.php?title=Occupational_noise&action=edithttp://en.wikipedia.org/wiki/Noise_health_effectshttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Marathon_Petroleum_Companyhttp://en.wikipedia.org/wiki/Garyville%2C_Louisianahttp://en.wikipedia.org/wiki/1976http://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Tenerifehttp://en.wikipedia.org/wiki/Oil_refinery#_note-2%23_note-2http://en.wikipedia.org/wiki/Californiahttp://en.wikipedia.org/wiki/Contra_Costa_Countyhttp://en.wikipedia.org/wiki/Solano_Countyhttp://en.wikipedia.org/wiki/Solano_Countyhttp://en.wikipedia.org/wiki/Richmond%2C_Californiahttp://en.wikipedia.org/wiki/Martinez%2C_Californiahttp://en.wikipedia.org/wiki/Pacheco%2C_Californiahttp://en.wikipedia.org/wiki/Concord%2C_Californiahttp://en.wikipedia.org/wiki/Pittsburg%2C_Californiahttp://en.wikipedia.org/wiki/Vallejo%2C_Californiahttp://en.wikipedia.org/wiki/Benicia%2C_Californiahttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=4http://en.wikipedia.org/wiki/Desalter


17/114

Vacuum Distillation Unit (further distills residual bottoms after atmospheric

distillation)

Naphtha HydrotreaterUnit (desulfurizes naphtha from atmospheric distillation.Must hydrotreat the naphtha before sending to a Catalytic Reformer Unit.)

Catalytic ReformerUnit (contains catalyst used to convert the naphtha-boiling

range molecules into higher octane reformate (reformer product). The reformatehas higher content of aromatics, olefins, and cyclic hydrocarbons). An important

byproduct of a reformer is hydrogen released during the catalyst reaction. The

hydrogen is used either in the hydrotreaters and hydrocracker.)

Distillate Hydrotreater Unit (desulfurizes distillate (diesel) after atmospheric

distillation)

Fluid Catalytic Cracking (FCC) Unit (upgrades heavier fractions into lighter,

more valuable products) HydrocrackerUnit (upgrades heavier fractions into lighter, more valuable

products)

Coking unit (processes asphalt into gasoline and diesel fuel, leaving coke as a

residual product) Alkylation unit (produces high octane component for gasoline blending)

Dimerization Unit

Isomerization Unit (converts linear molecules to higher octane branched

molecules for blending into gasoline or feed to alkylation units)

Steam reforming Unit (produces hydrogen for the hydrotreaters or hydrocracker)

Liquified gas storage units for propane and similar gaseous fuels at pressuresufficient to maintain in liquid form - these are usually spherical or bullets

(horizontal cylinder with rounded ends).

Storage tanks for crude oil and finished products, usually cylindrical, with somesort of vapor enclosure and surrounded by an earthberm to contain spills

Amine gas treater,Claus unit, and tail gas treatment for processinghydrogen

sulfide from hydrodesulfurization

Utility units such as cooling towers for circulating cooling water, boiler plants for

steam generation, and wastewatercollection and treating systems to make such

water suitable for reuse or for disposal.

[edit] Specialty end products

These will blend various feedstocks, mix appropriate additives, provide short term

storage, and prepare for bulk loading to trucks, barges, product ships, and railcars.

Gaseous fuels such aspropane, stored and shipped in liquid form under pressurein specialized railcars to distributors.

Liquid fuels blending (producing automotive and aviation grades of gasoline,

kerosene, various aviation turbine fuels, and diesel fuels, adding dyes, detergents,

antiknock additives, oxygenates, and anti-fungal compounds as required).Shipped by barge, rail, and tanker ship. May be shipped regionally in dedicated

pipelinesto point consumers, particularly aviation jet fuel to major airports, or
http://en.wikipedia.org/wiki/Vacuum_Distillationhttp://en.wikipedia.org/wiki/Hydrotreaterhttp://en.wikipedia.org/wiki/Catalytic_reforminghttp://en.wikipedia.org/wiki/Reformatehttp://en.wikipedia.org/wiki/Cracking_(chemistry)http://en.wikipedia.org/wiki/Cracking_(chemistry)http://en.wikipedia.org/wiki/Coker_unithttp://en.wikipedia.org/wiki/Alkylationhttp://en.wikipedia.org/wiki/Dimerizationhttp://en.wikipedia.org/wiki/Isomerizationhttp://en.wikipedia.org/wiki/Steam_reforminghttp://en.wikipedia.org/wiki/Bermhttp://en.wikipedia.org/wiki/Amine_gas_treaterhttp://en.wikipedia.org/wiki/Amine_gas_treaterhttp://en.wikipedia.org/wiki/Claus_processhttp://en.wikipedia.org/wiki/Claus_processhttp://en.wikipedia.org/wiki/Hydrogen_sulfidehttp://en.wikipedia.org/wiki/Hydrogen_sulfidehttp://en.wikipedia.org/wiki/Hydrogen_sulfidehttp://en.wikipedia.org/wiki/Hydrodesulfurizationhttp://en.wikipedia.org/wiki/Cooling_towershttp://en.wikipedia.org/wiki/Wastewaterhttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=5http://en.wikipedia.org/wiki/Propanehttp://en.wikipedia.org/wiki/Pipeline_transporthttp://en.wikipedia.org/wiki/Pipeline_transporthttp://en.wikipedia.org/wiki/Vacuum_Distillationhttp://en.wikipedia.org/wiki/Hydrotreaterhttp://en.wikipedia.org/wiki/Catalytic_reforminghttp://en.wikipedia.org/wiki/Reformatehttp://en.wikipedia.org/wiki/Cracking_(chemistry)http://en.wikipedia.org/wiki/Cracking_(chemistry)http://en.wikipedia.org/wiki/Coker_unithttp://en.wikipedia.org/wiki/Alkylationhttp://en.wikipedia.org/wiki/Dimerizationhttp://en.wikipedia.org/wiki/Isomerizationhttp://en.wikipedia.org/wiki/Steam_reforminghttp://en.wikipedia.org/wiki/Bermhttp://en.wikipedia.org/wiki/Amine_gas_treaterhttp://en.wikipedia.org/wiki/Claus_processhttp://en.wikipedia.org/wiki/Hydrogen_sulfidehttp://en.wikipedia.org/wiki/Hydrogen_sulfidehttp://en.wikipedia.org/wiki/Hydrodesulfurizationhttp://en.wikipedia.org/wiki/Cooling_towershttp://en.wikipedia.org/wiki/Wastewaterhttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=5http://en.wikipedia.org/wiki/Propanehttp://en.wikipedia.org/wiki/Pipeline_transport


18/114

piped to distributors in multi-product pipelines using product separators called

pipeline inspection gauges("pigs").

Lubricants (produces light machine oils, motor oils, and greases, adding viscositystabilizers as required), usually shipped in bulk to an offsite packaging plant.

Wax, used in the packaging offrozen foods, among others. May be shipped in

bulk to a site to prepare as packaged blocks. Sulfuric acid finishing and shipping. This is a useful industrial material, usually

prepared and shipped as the acid precursoroleum, a byproduct of sulfur removal

from fuels.

Bulktarshipping for offsite unit packaging for use in tar-and-gravel roofing.

Asphalt unit. Prepares bulk asphalt for shipment.

Petroleum coke, used in specialty carbon products or as solid fuel.

[edit] Co-plant siting

Frequently a chemical plant will be sited adjacent to a refinery, utilizing intermediate

products as feedstocks for the production of specialized materials such asplastics oragrichemicals.

[edit] History

The world's first oil refinery opened at Ploieti, Romania in1856[4]. Several other

refineries were built at that location with investment from United States companies

before being taken over byNazi Germany during World War II. Most of these refineries

were bombarded by the US Air Force in Operation Tidal Wave,August 1, 1943. Sincethen they have been rebuilt, and currently pose somewhat of an environmental concern.

Another early example is Oljen, now preserved as a museum at the UNESCOworld

heritage siteEngelsberg. It started operation in 1875 and is part of the EcomuseumBergslagen.

It is difficult to exactly state which is largest oil refinery in the world. At one time this

was claimed to be Ras Tanura,Saudi Arabia, owned by Saudi Aramco. For most of the

20th century, the largest refinery of the world was that ofAbadan in Iran. This refinerysuffered extensive damage in the IRAN/IRAQ war. The Guinness Book of World

Records now (October 2006) records the BP Amoco refinery in Texas City, USA, as the

refinery with the largest capacity (433,000 barrels/day which is approximately

15,143,482 Imperial Gallon).

Early US refineries processed crude oil to recover the kerosene. Other products (like

gasoline) were considered wastes and were often dumped directly into the nearest river.

The invention of the automobile shifted the demand to gasoline and diesel, which remainthe primary refined products today. Refineries pre-dating the EPA were very toxic to the

environment. Strict legislation has mandated that refineries meet modern air and water

cleanliness standards. In fact, obtaining a permit to build even a modern refinery with
http://en.wikipedia.org/wiki/Pipeline_inspection_gaugehttp://en.wikipedia.org/wiki/Pipeline_inspection_gaugehttp://en.wikipedia.org/wiki/Lubricanthttp://en.wikipedia.org/wiki/Waxhttp://en.wikipedia.org/wiki/Frozen_foodhttp://en.wikipedia.org/wiki/Frozen_foodhttp://en.wikipedia.org/wiki/Sulfuric_acidhttp://en.wikipedia.org/wiki/Oleumhttp://en.wikipedia.org/wiki/Oleumhttp://en.wikipedia.org/wiki/Tarhttp://en.wikipedia.org/wiki/Tarhttp://en.wikipedia.org/wiki/Asphalthttp://en.wikipedia.org/wiki/Petroleum_cokehttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=6http://en.wikipedia.org/wiki/Chemical_planthttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Agrichemicalshttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=7http://en.wikipedia.org/wiki/Ploie%C5%9Ftihttp://en.wikipedia.org/wiki/Romaniahttp://en.wikipedia.org/wiki/1856http://en.wikipedia.org/wiki/1856http://en.wikipedia.org/wiki/Oil_refinery#_note-3%23_note-3http://en.wikipedia.org/wiki/Oil_refinery#_note-3%23_note-3http://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Nazi_Germanyhttp://en.wikipedia.org/wiki/Nazi_Germanyhttp://en.wikipedia.org/wiki/World_War_IIhttp://en.wikipedia.org/wiki/US_Air_Forcehttp://en.wikipedia.org/wiki/Operation_Tidal_Wavehttp://en.wikipedia.org/wiki/Operation_Tidal_Wavehttp://en.wikipedia.org/wiki/August_1http://en.wikipedia.org/wiki/1943http://en.wikipedia.org/w/index.php?title=Olje%C3%B6n&action=edithttp://en.wikipedia.org/wiki/UNESCOhttp://en.wikipedia.org/wiki/UNESCOhttp://en.wikipedia.org/wiki/World_heritage_sitehttp://en.wikipedia.org/wiki/World_heritage_sitehttp://en.wikipedia.org/wiki/World_heritage_sitehttp://en.wikipedia.org/wiki/Engelsberghttp://en.wikipedia.org/wiki/Engelsberghttp://en.wikipedia.org/w/index.php?title=Ecomuseum_Bergslagen&action=edithttp://en.wikipedia.org/w/index.php?title=Ecomuseum_Bergslagen&action=edithttp://en.wikipedia.org/wiki/Ras_Tanurahttp://en.wikipedia.org/wiki/Ras_Tanurahttp://en.wikipedia.org/wiki/Saudi_Arabiahttp://en.wikipedia.org/wiki/Saudi_Arabiahttp://en.wikipedia.org/wiki/Saudi_Aramcohttp://en.wikipedia.org/wiki/Saudi_Aramcohttp://en.wikipedia.org/wiki/Abadanhttp://en.wikipedia.org/wiki/Iranhttp://en.wikipedia.org/wiki/Iranhttp://en.wikipedia.org/wiki/Gallonhttp://en.wikipedia.org/wiki/Kerosenehttp://en.wikipedia.org/wiki/Pipeline_inspection_gaugehttp://en.wikipedia.org/wiki/Lubricanthttp://en.wikipedia.org/wiki/Waxhttp://en.wikipedia.org/wiki/Frozen_foodhttp://en.wikipedia.org/wiki/Sulfuric_acidhttp://en.wikipedia.org/wiki/Oleumhttp://en.wikipedia.org/wiki/Tarhttp://en.wikipedia.org/wiki/Asphalthttp://en.wikipedia.org/wiki/Petroleum_cokehttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=6http://en.wikipedia.org/wiki/Chemical_planthttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Agrichemicalshttp://en.wikipedia.org/w/index.php?title=Oil_refinery&action=edit&section=7http://en.wikipedia.org/wiki/Ploie%C5%9Ftihttp://en.wikipedia.org/wiki/Romaniahttp://en.wikipedia.org/wiki/1856http://en.wikipedia.org/wiki/Oil_refinery#_note-3%23_note-3http://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/Nazi_Germanyhttp://en.wikipedia.org/wiki/World_War_IIhttp://en.wikipedia.org/wiki/US_Air_Forcehttp://en.wikipedia.org/wiki/Operation_Tidal_Wavehttp://en.wikipedia.org/wiki/August_1http://en.wikipedia.org/wiki/1943http://en.wikipedia.org/w/index.php?title=Olje%C3%B6n&action=edithttp://en.wikipedia.org/wiki/UNESCOhttp://en.wikipedia.org/wiki/World_heritage_sitehttp://en.wikipedia.org/wiki/World_heritage_sitehttp://en.wikipedia.org/wiki/Engelsberghttp://en.wikipedia.org/w/index.php?title=Ecomuseum_Bergslagen&action=edithttp://en.wikipedia.org/w/index.php?title=Ecomuseum_Bergslagen&action=edithttp://en.wikipedia.org/wiki/Ras_Tanurahttp://en.wikipedia.org/wiki/Saudi_Arabiahttp://en.wikipedia.org/wiki/Saudi_Aramcohttp://en.wikipedia.org/wiki/Abadanhttp://en.wikipedia.org/wiki/Iranhttp://en.wikipedia.org/wiki/Gallonhttp://en.wikipedia.org/wiki/Kerosene


19/114

minimal impact on the environment (other than CO2 emmissions) is so difficult and

costly that no new refineries have been built in the United States since 1976. As a result,

the US is becoming more and more dependent on the imports of finished gasoline, asopposed to incremental crude oil.

Crude Distillation

Distillation is the first step in the processing of crude oil and it takes place in a tall steeltower called a fractionation column. The inside of the column is divided at intervals by

horizontal trays. The column is kept very hot at the bottom (the column is

insulated) but as different hydrocarbons boil at different

temperatures, the temperature gradually reduces towards thetop, so that each tray is a little cooler than the one below.


20/114

The crude needs to be heated up before entering the fractionation column and this is done

at first in a series of heat exchangers where heat is taken from other process streams

which require cooling before being sent to rundown. Heat is also exchanged againstcondensing streams from the main column. Typically, the crude will be heated up in this

way upto a temperature of 200 - 280 0C, before entering a furnace.

As the raw crude oil arriving contains quite a bit of water and salt, it is normally sent for

salt removing first, in a piece of equipment called a desalter. Upstream the desalter, thecrude is mixed with a water stream, typically about 4 - 6% on feed. Intense mixing takes

place over a mixing valve and (optionally) as static mixer. The desalter, a large liquid full

vessel, uses an electric field to separate the crude from the water droplets. It operates bestat 120 - 150 0C, hence it is conveniently placed somewhere in the middle of the preheat

train.

Part of the salts contained in the crude oil, particularly magnesium chloride, are

hydrolysable at temperatures above 120 0C. Upon hydrolysis, the chlorides get converted

into hydrochloric acid, which will find its way to the distillation column's overhead

where it will corrode the overhead condensers. A good performing desalter can remove

about 90% of the salt in raw crude.

Downstream the desalter, crude is further heated up with heat exchangers, and starts

vaporising, which will increase the system pressure drop. At about 170 -200 0C, the crude

will enter a 'pre-flashvessel', operating at about 2 - 5 barg, where the vapours areseparated from the remaining liquid. Vapours are directly sent to the fractionation

column, and by doing so, the hydraulic load on the remainder of the crude preheat train

and furnace is reduced (smaller piping and pumps).


21/114

Just upstream the preflash vessel, a small caustic stream is mixed with the crude, in order

to neutralise any hydrochloric acid formed by hydrolysis. The sodium chloride formed

will leave the fractionation column via the bottom residue stream. The dosing rate ofcaustic is adjusted based on chloride measurements in the overhead vessel (typically 10 -

20 ppm).

At about 200 - 280 0C the crude enters the furnace where it is heated up further to about

330 -370 0C. The furnace outlet stream is sent directly to the fractionation column. Here,it is separated into a number of fractions, each having a particular boiling range.

At 350 0C, and about 1 barg, most of the fractions in the crude oil vapourise and rise up

the column through perforations in the trays, losing heat as they rise. When each fraction

reaches the tray where the temperature is just below its own boiling point, it condensesand changes back into liquid phase. A continuous liquid phase is flowing by gravity

through 'downcomers' from tray to tray downwards. In this way, the different fractions

are gradually separated from each other on the trays of the fractionation column. The

heaviest fractions condense on the lower trays and the lighter fractions condense on thetrays higher up in the column. At different elevations in the column, with special trays

called draw-off trays, fractions can be drawn out on gravity through pipes, for furtherprocessing in the refinery.

At top of the column, vapours leave through a pipe and are routed to an overhead

condenser, typically cooled by air fin-fans. At the outlet of the overhead condensers, at

temperature about 40 0C, a mixture of gas, and liquid naphtha exists, which is falling intoan overhead accumulator. Gases are routed to a compressor for further recovery of LPG

(C3/C4), while the liquids (gasoline) are pumped to a hydrotreater unit for sulfur

removal.

A fractionation column needs a flow of condensing liquid downwards in order to providea driving force for separation between light and heavy fractions. At the top of the column

this liquid flow is provided by pumping a stream back from the overhead accumulator

into the column. Unfortunately, a lot of the heat provided by the furnace to vaporisehydrocarbons is lost against ambient air in the overhead fin-fan coolers. A clever way of

preventing this heat lost of condensing hydrocarbons is done via the circulating refluxes

of the column. In a circulating reflux, a hot side draw-off from the column is pumpedthrough a series of heat exchangers (against crude for instance), where the stream is

cooled down. The cool stream is sent back into the column at a higher elevation, where it

is been brought in contact with hotter rising vapours. This provides an internal

condensing mechanism inside the column, in a similar way as the top reflux does whichis sent back from the overhead accumulator. The main objective of a circulating reflux

therefore is to recover heat from condensing vapours. A fractionating column will have

several (typically three) of such refluxes, each providing sufficient liquid flow down thecorresponding section of the column. An additional advantage of having circulating

refluxes is that it will reduce the vapour load when going upwards in the column. This

provided the opportunity to have a smaller column diameter for top sections of the tower.Such a reduction in diameter is called a 'swage'.


22/114

The lightest side draw-off from the fractionating column is a fraction called kerosene,

boiling in the range 160 - 280 0C, which falls down through a pipe into a smaller column

called 'side-stripper'. The purpose of the side stripper is to remove very lighthydrocarbons by using steam injection or an external heater called 'reboiler'. The

stripping steam rate, or reboiled duty is controlled such as to meet the flashpoint

specification of the product. Similarly to the atmospheric column, the side stripper hasfractionating trays for providing contact between vapour and liquid. The vapours

produced from the top of the side stripper are routed back via pipe into the fractionating

column.

The second and third (optional) side draw-offs from the main fractionating column aregasoil fractions, boiling in the range 200 - 400 0C, which are ultimately used for blending

the final diesel product. Similar as with the kerosene product, the gasoil fractions (light

and heavy gasoil) are first sent to a side stripper before being routed to further treatingunits.

At the bottom of the fractionation column a heavy, brown/black coloured fraction calledresidue is drawn off. In order to strip all light hydrocarbons from this fraction properly,

the bottom section of the column is equipped with a set of stripping trays, which areoperated by injecting some stripping steam (1 - 3% on bottom product) into the bottom of

the column.

Hydrotreating

The objective of the Hydrotreating prococess is to remove suplur as well as other unwantedcompunds, e.g. unsaturated hydrocarbons, nitrogen from refinery process streams.

Until the end of World War 2, there was little incentive for the oil industry to pay significantattention to improving product quality by hydrogen treatment. However, soon after the war theproduction of high sulphur crudes increased significantly, which gave a more stringent demand onthe product blending flexibility of refineries, and the marketing specifications for the productsbecame tighter, largely due to environmental considerations. Furthermore, the catalyst used inthe Platforming process can only handle sulfur in the very low ppm level, so hydrotreating ofnaphtha became a must. The necessity for hydrotreating of middle distillates (kerosene/gasoil)originates from pressure to reduce sulfur emissions into the environment. Overall, this situation

resulted in an increased necessity for high sulphur removal capability in many refineries.

As catalytic reforming gives hydrogen as a byproduct, it gave additional momentum to thedevelopment of sulphur removal process by hydrogen treatment. In this treatment, the sulphurcompounds are removed by converting them into hydrogen sulphide by reaction with hydrogen inthe presence of a catalyst. This results in high liquid product yields, since only sulphur isremoved. Furthermore, the hydrogen sulphide produced can be easily removed from the productgas stream, for example by an amine wash. In this way, hydrogen sulphide is recovered as a
http://www.cheresources.com/refining3.shtmlhttp://www.cheresources.com/refining2.shtmlhttp://www.cheresources.com/refining3.shtml


23/114

higly concentrated stream and can be furtherconverted into elemental sulphur via the "Claus"process.

Hydrodesulphursiation has been extensively usedcommercially for treating naphtha as feedstock for

catalytic reformers to meet the very stringent sulphuirspecification of less than 1 ppm wt to protect theplatinum catalyst. It has also been widely used forremoval of sulphur compounds from kerosine andgasoils to make them suitable as blendingcomponents. In cases where products are fromcatalytic or thermal crackers, hydrogen treatment isused to improve product quality specifications likecolour, smoke point, cetane index, etc.

For Hydrotreating, two basic processes are applied,the liquid phase (or trickle flow) process for kerosine

and heavier straight-run and cracked distillates up to vacumn gas oil and the vapour phase

process for light straight-run and cracked fractions.

Both processes use the same basic configuration: the feedstock is mixed with hydrogen-richmake up gas and recycle gas. The mixture is heated by heat exchange with reactor effluent andby a furnace and enters a reactor loaded with catalyst. In the reactor, the sulphur amd nitrogencompounds present in the feedstock are converted into hydrogen sulphide and ammoniarespectively. The olefins present are saturated with hydrogen to become di-olefins and part of thearomatics will be hydrogenated. If all aromatics needs to be hydrogenated, a higher pressure isneeded in the reactor compared to the conventional operating mode.

The reactor operates at temperatures in the range of 300-380 0C and at a pressure of 10-20 barfor naphta and kero, as compared with 30-50 bar for gasoil, with excess hydrogen supplied. The

temperature should not exceed 3800

C, as above this temperature cracking reactions can occur,which deteriorates the colour of the final product. The reaction products leave the reactor and,after having been cooled to a low temperature, typically 40-50 0C, enter a liquid/gas separationstage. The hydrogen-rich gas from the high pressure separation is recycled to combine with thefeedstock, and the low pressure off-gas stream rich in hydrogen sulphide is sent to a gas-treatingunit, where hydrogen sulphide is removed. The clean gas is then suitable as fuel for the refineryfurnaces. The liquid stream is the product from hydotreating. It is normally sent to a strippingcolumn where H2S and other undesirable components are removed, and finally, in cases wheresteam is used for stripping, the product is sent to a vacumn drier for removal of water. Somerefiners use a salt dryer in stead of a vacuum drier to remove the water.

The catalyst used is normally cobalt, molybdenum and nickel finely distributed on aluminaextrudates. It slowly becomes choked by coke and must be renewed at regular

intervals (typically 2-3 years). It can be regenerated (by burning off the coke) and reused typicallyonce or twice before the breakdown of the support's porousstructure unacceptably reduces its activity. Catayst regeneration is,nowadays, mainly carried out ex- situ by specialised firms. Othercatalysts have also been developed for applications where denitrification is the predominantreaction required or where high stauration of olefins is necessary.


24/114

A more recent development is the application of Hydrotreating for pretreatment of feedstcok forthe catalytic cracking process. By utilisation of a suitable hydrogenation-promoting catalyst forconversion of aromatics and nitrogen in potential feedstocks, and selection of severe operatingconditions, hydrogen is taken up by the aromatic molecules. The increased hydrogen content ofthe feedstock obtained by this treatment leads to significant conversion advantages insubsequent catalytic cracking, and higher yield of light products can be achieved.

Hydrotreatment can also be used for kerosine smoke point improvement (SPI). It closelyresembles the conventional Hydrotreating Process however an aromatic hydrogenation catalystconsisting of noble metals on a special carrier is used. The reactor operates at pressure range of50-70 bar and temperatures of260-320 0C. To restrict temperature rise due to the highly exothermic aromatics conversionreactions, quench oil is applied between the catalysts beds. The catalyst used is very sensitive totraces of sulphur and nitrogen in the feedstock and therefore pretreatment is normally applied in aconventional hydrotreater before kerosine is introduced into the SPI unit. The main objective ofSmoke Point Improvement is improvement in burning characteristics as the kerosine aromaticsare converted to naphthenes.

Hydrotreatment is also used for production of feedstocks for isomersiation unit from pyrolysis

gasoline (pygas) which is one of the byproducts of steam cracking of hydrocarbon fractions suchas naphtha and gasoil.

A hyrotreater and a hydrodesulphuriser are basically the same process but a hydotreater termedis used for treating kerosene or lighter feedstock, while a hydodesulhuriser mainly refers to gasoiltreating. The hydrotreatment process is used in every major refinery and is therefore also termedas the work horse of the refinery as it is the hydrotreater unit that ensures several significantproduct quality specifications. In most countries the Diesel produced is hydrodesulhurised beforeits sold. Sulphur specifications are getting more and more stringent. In Asia, countries such asThailand, Singapore and Hong Kong already have a 0.05%S specification and largehydrodesulphurisation units are required to meet such specs.

The by-products obtained from HDT/HDS are light ends formed from a small amounts of cracking

and these products are used in the refinery fuelgas pool. The other main by-product is HydrogenSulphide which is oxidized to sulphur and sold to the chemical industry for further processing

In combination with temperature, the pressure level (or rather the partial pressure of hydrogen)generally determines the types of components that can be removed and also determines theworking life of the catalyst. At higher (partial) pressures, the desulphurisation process is 'easier',however, the unit becomes more expensive for instance due to larger compressors and heavierreactors. Also, at higher pressure, the hydrogen consumption of the unit increases, which can bea signficant cost factor for the refinery. The minimum pressure required typically goes up with therequired severity of the unit, i.e. the heavier the feedstock, or the lower levels of sulphur inproduct required.

Platforming

Motor gasoline (Mogas) production starts with the distillation of crude oil. One of the products outof that process is a fraction of low octane gasoline, normally referred to as naphtha, typicallyboiling in the range 100 - 160 0C. Other gasoline fractions are produced as a result of secondaryprocesses like catalytic cracking, isomerisation, alkylation and platforming. Petrol is then
http://www.cheresources.com/refining.shtmlhttp://www.cheresources.com/refining.shtmlhttp://www.cheresources.com/refining.shtml


25/114

produced by blending a variety of these gasoline components of different qualities to meet aseries of product specifications.

One very important property of Mogas is the octane number, which influences "knocking" or"pinking" behaviour in the engine of cars. Traditionally lead compounds have been added topetrol to improve the octane number. Over the past years, in many countries legislation has been

implemented aimed at reducing the emission of lead from exhausts of motor vechiles and this,calls for other means of raising the octane number.

The role of a platformer is to pave the way for this by a process which reforms the molecules inlow octane naphtha to produce a high octane gasoline component. This is achieved by employinga catalyst with platinum as its active compound; hence the name Platformer. For many refinerycatalyst applications, a promoter is used, and in the platforming process, it is a chloride promoterwhich stimulates the 'acidity' of the catalyst and thereby the isomerisation reactions. Often, abimetallic catalyst is used, i.e. in addition to the platinum, a second metal, for instance Rhenium ispresent on the catalyst. The main advantage is a higher stability under reforming conditions. Thedisadvantage is that the catalyst becomes more sensitive towards poisons, process upsets andmore susceptible to non-optimum regenerations.

Chemistry:

The main reactions of platforming process are as follows:

Dehydrogenation of naphthenes, yielding aromatics and hydrogen Dehydro-isomerisation of alkyl cyclopentanes to aromatic and hydrogen Isomerisation of paraffins and aromatics

Dehydrocyclisation of paraffins to aromatics and hydrogen Hydrocracking of paraffins and naphthenes to ligher, saturated paraffins at the expense

of hydrogen

The process literally re-shapes the molecules of the feed in a reaction in the presence of aplatinum catalyst. Normally it is the hydrocarbon in the C6-C10 parafins that get converted toaromatics.


26/114


27/114

shutdown for a typical runlength of 3 - 6 years. After 300 - 400 cycles of reaction/regeneration,the surface area of the catalyst will have dropped to a level (120 - 130 m2/g) that it becomesmore difficult to maintain catalyst activity and at such a time normally the catalyst will be replacedby a fresh batch. The batch of 'spent' catalyst is then sent for platinum reclaim to recover thevaluable precious metals.

For economic reasons, the design capacities of Platformer units vary from 1000 - 4500 t/d;operating pressures can vary over a wide range, units with from 3.5 barg up to 30 barg can befound, whereby the latest generation CCR's are typically at the lower pressure range. A lowerpressure enhances the endothermic reactions, which gives less cracking reactions and thereby ahigher liquid yield. However, at a lower reactor operating pressure, the hydrogen partial pressurewill be lower as well, which favours coke formation. The reason why semi regen platformers willnot operate at a too low pressure, otherwise the cycle length between regenerations becomes toshort. A second disadvantage of operating at a lower pressure is that a larger compressor will berequired to boost the pressure of the hydrogen up to the normal pressure of the hydrogen system(about 20 barg). Typical design reformate octane numbers are in the 95-104 range. The reactortemperature is in a region of 450-530 0C.

At the outlet of the last reactor the product is still well above 400 0C. It is cooled down against

cold feed in massive heat exchanger, either a so called 'Texas Tower' or a Packinox plate-packheat exchanger. The special design of those heat exchangers ensures that minimum heat lossoccurs in order to minimise the fuel consumption of the furnaces. After passing the feed/effluentexchanger, the reaction products are cooled in air/water coolers and routed to a productseparator, where the hydrogen is the main gaseous product. Part of the hydrogen produced isrecycled back (via a compressor) to the feed, in order to maintain a high enough hydrogen partialpressure in the reactors. The remainder of the gases are compressed and brought in contactagain with the liquid from the product separator. This is step is called 'recontacting' and is done inorder to recover as much as possible hydrocarbons from the hydrogen produced. The reactorproduct, now in liquid form, goes on to the platformer stabiliser which removes Liquid PetroleumGas ( LPG) and other gases to leave a liquid high octane gasoline component called platformate,ready for blending into the refinery mogas pool. Summarising, the Platformer unit produces about85% liquid platformate, 10% hydrogen and 5% LPG.

The Continuous Catalytic Reforming unit or better known as CCR Platformer is licensed by UOP,Universal Oil Products, based in USA. More recently, other technology vendors have copied theconcept, one of the main competitors for UOP in this field is IFP from France.

Main Equipment in a CCR Platformer:

A CCR typically contains a feed/effluent heat exchanger (Texas Tower or Packinox), 4 furnaces,4 reactors, a regenerator, overhead recontacting section, net gas compressor, recycle gascompressor and a stabiliser column.

Isomerization

The isomerisation process involves the transformation of one molecular structure into another(isomer) whose component atoms are the same but arranged in a different geometrical structure.Since isomers may differ greatly in physical and chemical properties, isomerisation offers thepossibility of converting less desirable compounds into isomers with desirable properties, inparticular to convert n-paraffins into iso-paraffins, thereby increasing the octane of thehydrocarbon stream. The main fields of application of isomerisation are:

ISOMERISATION of normal butane into isobutane


28/114


29/114

phase and the presence of hydogen. For these reasons, these process are called hydro-isomerisation processes.

The first hydro- isomerisation unit was introduced nin 1953 by UOP, followed in 1965 by the firstBP one, while in 1970 the first Shell hydro-isomerisation (HYSOMER) unit was started up. Atpresent the following hydro-isomerisation processes are commercially available:

UOP BUTAMER for butane isomerisation UOP PENEX for pentane/hexane isomerisation BP C4 isomerisation for butane isomerisation BP C5/C6 isomerisation for pentane/hexane isomerisation SHELL Hysomer for pentane/hexane isomerisation

All these processes takes place in the vapour phase on a fixed bed catalyst containing platinumon a solid carrier.

As an example, the Shell Hysomer process will be briefly described. The liquid feedstock ispentane/hexane from light naphtha. naphtha splitters are widely used to split light naphtha, heavynaphtha and also LPG. The light naphtha (C5/C6) is combined with the recycle gas/ fresh gasmixture. The resultant combined reactor feed is routed to a feed/ effluent heat exchanger, whereit is heated and completely vaporised by the effluent of the reactor. The vapourised combinedreactor feed is further heated to the desired reactor inlet temperature in the reactor charge heater.The hot charge enters the Hysomer reactor at the top and flows downwards through the catalystbed, where a portion of normal and mono- branched paraffins is converted into higher branched(high octane) components. Temperature rise from the heat of reaction release is controlled by acold quench gas injection into the reactor. Reactor effluent is cooled and subsequently separatedin the product separator into two streams: a liquid product (isomerate) and a recycle gas streamreturning to the reactor via the recycle gas compressor.

The catalyst is a dual function catalyst consisting of platinum on a zeolite basis, highly stable andregenerable.

Temperatures and pressure vary in a range of 230 - 285 0C and 13-30 bar, C5/C6 content inproduct relative to that in feed is 97% or better, and octane upgrading ranges between 8 and 10points, depending on feedstock quality. The Hysomer process can be integrated with catalyticreformer, resulting in substantial equipment savings, or with iso-normal separation processeswhich allows for a complete conversion of pentane/hexane mixtures into isoparaffin mixtures. Aninteresting application in this field is the total isomerisation process (TIP) in which theisomerisation is completely integrated with a Union Carbide molecular sieve separation processor the naphtha IsoSiv Process by UOP.

Highlights of TIP

The following are some of the highlights of the TIP process:

A. TIP has been in commercial operation since 1975B. UOP manufacturers both the zeolite isomerisation catalyst and the IsoSiv Grade MolecularSieve adsorbent.C. UOP's zeolite catalyst will tolerate sulfur and/or water upsets, the effects of which are usuallyreversible, either with time or by in situ regeneration (which minimises any down time).D. The expected life of the catalyst and adsorbent is 10 years or more.F. The combination of zeolite isomerisation and IsoSiv molecular separation is possible becauseeach station has similar operating conditions of temperature, pressure and environment. Thiseliminates the need for a second compressor, intermediate stabilisation and the costs associated


30/114

with cooling, purifying and reheating the recylce normal paraffins.G. TIP and IsoSiv separation permits maximum flexibility in changing the C5/C6 ratio andiso/normal ratio of the feed.

Conclusion:

Nowadays many refiners are looking into the isomerisation processes to add potential extra valueand complimentary to the platforming process. Directly both the platforming and isomerisationprocess work hand in hand in several ways. C5 paraffins tend to crack away in the platformer, butgive high upgrading in the isomerisation unit. C6 components convert nicely to benzene in theplatformer, but nowadays the specs on aromatics and benzene are tightening, which makesconversion of these components to C6 isomers preferred. Furthermore, benzene is hydrogenatedin the isomerisation unit. By adjusting the cutpoint between the light and heavy naphtha, i.e. thecutpoint between the feed to the isomerisation feed and the platformer feed, the refiner has theflexibility to control the benzene content of its gasoline pool.

Hydrocracking

Introduction

The need for gasoline of a higher quality than that obtained by catalytic cracking led to thedevelopment of the hydrocracking process. The history of the process goes back to the later1920s when a plant for the commercial hydrogenation of brown coal was commissioned at Leunain Germany. Tungsten sulphide was used as a catalyst in this one-stage unit , in which highreaction pressures, 200-300 bar, were applied. The catalyst displayed a very high hydrogenationactivity: the aromatic feedstock, coal and heavy fractions of oil, containing sulphur, nitrogen andoxygen, was virtually completely converted into paraffins and isoparaffins. The result of the Leunaplant - loss of octane number from aromatic hydrogenation of impurities in the feedstock, notablynitrogen compounds, followed by a hydrocracking step. In 1939, ICI developed the second-stagecatalyst for a plant that contributed largely to Britain's supply of aviation gasoline in the

subsequent years.

During World War II, two stage processes were applied on a limited scale in Germany, Britain andUSA. In Britain, feedstock were creosote from coal tar and gas oil from petroleum. In the USA,Standard Oil of New Jersey operated a plant at Baton Rouge, producing gasoline from aVenezuelan kerosine/light gasoil fraction. Operating conditions in those units were comparable:approximate reaction temperature 400 0C and reaction pressures of 200-300 bar.


31/114

After the war, commercial hydrocracking was stopped because the process was too expensive.Hydocracking research, however, continued intensively. By the end of the 1950s, the process hadbecome economic, for which a number of reasons are identified.

The development of improved catalyst made it possible to operate the process at considerablylower pressure, about 70-150 bar.

This in turn resulted in a reduction in equipment wall thickness, whereas simultaneously,advances were made in mechanical engineering, especially in the field of reactor design and heattransfer. These factors, together with the availability of relativelylow cost hydrogen from steam reforming process, broughthydrocracking back on the refinery scene. The first units of the second generation were built inUSA to meet the demand for conversion of surplus fuel oil in the gasoline-oriented refineries.

Now, hdyrocracking is well established process from many licensors.

Basis for the Choice of Conversion Route

Refiners are continuously faced with trends towards increased conversion, better productqualities and more rapidly changing product patterns. Various processes are available that canmeet the requirements to a greater or lesser degree: coking, visbreaking/thermal cracking,catalytic cracking and hydrocracking.

The type of process applied and the complexity of refineries in various parts of the world aredetermined to a greater extent by the product distribution required. As a consequence, therelatively importance of the above process in traditionally fuel-oil dominated refineries such as


32/114


33/114


34/114

Catalytic Cracking

Introduction

Already in the 30's it was found that when heavy oil fractions are heated over clay type materials,

cracking reactions occur, which lead to significant yields of lighter hydrocarbons. While the searchwas going on for suitable cracking catalysts based on natural clays, some companiesconcentrated their efforts on the development of synthetic catalyst. This resulted in the syntheticamorphous silica-alumina catalyst, which was commonly used until 1960, when it was slightlymodified by incorporation of some crystalline material (zeolite catalyst). When the success of theHoudry fixed bed process was announced in the lat

45489448 Oil Gas Refining Basic

Documents

Transcript of 45489448 Oil Gas Refining Basic