Oil Refining Fundamentals

Refining Means. . .

1.To reduce to a pure state, to remove impurities

2.To improve or perfect

Components such as . . .

• Straight-Chain Hydrocarbons

• Olefins

• Cyclic H/C

• Aromatics (Benzene, toluene, xylenes)

• Mercaptans

• Hydrogen Sulfide (H2S)

• Greases

• Propane

• LPG

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What Is Crude Oil?

• Crude Oil is a liquid mixture of thousands of organic chemicals found underground. It is the result of organic matter decaying over thousands of years; hence the name fossil fuel

• Crude oil is found all over the world and varies tremendously in its density, aromatics, sulfur, and metals content

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Typical Elemental Composition of Typical Elemental Composition of Crude Oil at RefineryCrude Oil at Refinery

• Element Wt%

• Carbon 83-87

• Hydrogen 11-14

• Sulfur 0.5-2.5

• Nitrogen 0.1-0.2

• Oxygen 0.0-0.2

• Metals 0.0-100 ppm

Refining Crude Oil

Why do we need to refine the crude oil?Why can’t we build engines that run on crude oil?

That is why the crude oils must be purified and transformed into products having an almost constant composition, well adapted to their use. These transformations are carried out in refineries.

Let’s learn more about the refining and refineries…

We need to refine the crude oil because• Crude oil is an unstable mixture of several hydrocarbons in

varying quantities according to the density of the products• There is not one type of crude oil but a multitude of different

crudes• Different crudes contain dissolved gases, sulfur or acid products

which are very corrosive for metals

Introduction to Petroleum Refinery

A refinery is a factory. Just as a paper mill turns lumber into paper, a refinery takes crude oil and turns it into gasoline and hundreds of other useful products. A typical refinery costs billions of dollars to build and millions more to maintain A refinery runs twenty-four hours a day, 365 days a year and requires a large number of employees to run. A refinery can occupy as much land as several hundred football fields. Workers ride bicycles to move from place to place inside the complex. 

Typical refinery products are LPG, Gasoline, Kerosene, Diesel, Fuel oil, Lubricating oil, Paraffin wax, Asphalt and Tar

Petroleum is also the raw material for products such as fertilizers, pesticides, plastics and other polymers which are used in the manufacturing of fabrics such as silk.

What does refining actually do?Essentially, refining breaks crude oil down into its various components, which then are selectively reconfigured into new products. All refineries perform four basic steps: a) Separation (Distillation), b) Conversion (Cracking) and c) Reforming d) Blending & Treatment

Crude oil contains many components which differ in boiling points, relative solubility. Moreover crude oil can be categorized under

•Light•Heavy (Asphaltic)•Sweet (Non-sulfurous-less than 1% of sulfur)•Sour (Sulfurous-more than 1% of sulfur))

Crude oil processing consists of two partsPrimary Processing- Output is raw (primary) productsSecondary Processing- Output is commercial products which are used by us

Primary ProcessingCrude Oil Secondary

Processing

Raw Products

CommercialProducts

Separation Conversion

Primary processing involves distillation at atmospheric pressure or under vacuum. Distillation causes separation of breaking up of crude oil into various petrochemicals.

Primary Processing-Separation

Inside the towers, the liquids and vapors separate into components or fractions according to weight 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 weight liquids, including kerosene and diesel oil distillates, stay in the middle. (Heavier liquids, called gas oils, separate lower down, while the heaviest fractions with the highest boiling points settle at the bottom.)

Source- http://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/refinery.html

Distillation is done using two methods; a) Atmospheric distillation b) Vacuum Distillation

Secondary Processing-ConversionPrimary products require further adjustment of chemical composition in order to become suitable for sale or petrochemical processing. This transformation takes place during conversion stage. The most widely used conversion method is called cracking because it uses heat and pressure to "crack" heavy hydrocarbon molecules into lighter ones. A cracking unit consists of one or more tall, thick-walled, bullet-shaped reactors and a network of furnaces, heat exchangers and other vessels.

Conversion is directed towards maximum gasoline production

Cracking is not the only form of conversion. Other refinery processes, instead of splitting molecules, rearrange them to add value. Alkylation’s, for example, makes gasoline components by combining some of the gaseous byproducts of cracking.

The process, which essentially 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. We’ll learn more about these processes

Cracking unit

Source- http://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/refinery.html

Bases of Crude Oil

• Paraffin wax, contain very low amount of asphalt material with high quality lubricating oil, kerosene, used in the packaging of frozen foods, among others. May be shipped in bulk to a site to prepare as packaged blocks.

• Asphalt - it has very high amount of asphaltic material and contain residue of asphaltic material, major products are Gasoline, lubricating oil, kerosene used as a binder for gravel to form asphalt concrete, which is used for paving roads, lots, etc. An asphalt unit prepares bulk asphalt for shipment

• Mixed – it contains both Paraffin and asphalt, all type of petroleum products can be obtained, but yield is lower than others.

Products of Crude Oil• LPGContain carbon atom from C1 to C4, 40 degree Celsius, propane and butane, is used as a fuel and

as an intermediate in manufacturing petrochemicals, heating and cooking.• NaphthaContain carbon atom from C4 to C9, 60 to 100 degree Celsius, A low-octane gasoline product

used as a feedstock by the chemicals industry, as a feedstock for catalytic reforming, and in the production of hydrogen.

• GasolineContain carbon atom from C5 to C10, 40 to 205 degree Celsius, Different gasoline blends are

produced as regular or premium grades in both summer and winter formulations. Additives are often used to enhance performance and provide protection against oxidation and corrosion.

• KerosineContain carbon atom from C10 to C15, 175 to 325 degree Celsius,• Diesel OilContain carbon atom from C14 to C20, 250 to 350 degree Celsius, • Lubricating OilContain carbon atom from C20 to C50, 300 to 370 degree Celsius, • Fuel oilContain carbon atom from C50 to C70, 370 to 600 degree Celsius