2 What is Crude Oil & Crude Oil Refining? Crude oil, also known as black gold, is a thick, dark brown or greenish flammable liquid, which is found in the upper strata of some regions of the Earth's crustIt is a complex mixture of various hydrocarbons, (mainly, alkanes), along with trances of other chemicals and compounds (e.g. Sulphur)When extracted from underground, it ranges in density from very light to very heavy and in color, from yellow to blackCrude oil can be categorized as either "sweet crude" (where the sulphur content less than 0.5%) or "sour crude," (where the sulphur content is at least 2.5%)Crude oil must undergo several separation processes so that its components can be obtained and used as fuels or converted to more valuable productsThe process of transforming crude oil into finished petroleum products (that the market demands) is called crude oil refiningAn Oil Refinery
3 Distillation of Crude Oil We can separate the components of crude oil by taking advantage of the differences in their boiling points. This is done by simply heating up crude oil, allowing it to vaporize, and then letting the vapor to condense at different levels of the distillation tower (depending on their boiling points). This process is called fractional distillation and the products of the fractional distillation of crude oil is called fractionsA fraction from crude oil can be categorized into two categories:Refined Product: A crude oil fraction which contains a lot of individual hydrocarbons (e.g. gasoline, asphalt, waxes, and lubricants)Petrochemical Product: A crude oil fraction which contain one or two specific hydrocarbons of high purity (e.g. benzene, toluene, and ethylene).
4 AT THE BOTTOM OF THE DISTILLATION COLUMN Crude Oil RefiningAT THE TOP OF THE DISTILLATION COLUMNAT THE BOTTOM OF THE DISTILLATION COLUMNShort carbon chainsLong carbon chainsLight moleculesHeavy moleculesLow boiling pointsHigh boiling pointsGases & very runny liquidsThick, viscous liquidsVery volatileLow volatilityLight colourDark colourHighly flammableNot very flammable
5 Fractions of Crude Oil & Their Properties NameNumber of Carbon AtomsBoiling Point (°C)UsesRefinery Gas3 or 4below 30Bottled Gas (propane or butane).Gasoline7 to 9100 to 150Fuel for car engines.Naphtha6 to 1170 to 200Solvents and used in gasoline.Kerosene (paraffin)11 to 18200 to 300Fuel for aircraft and stoves.Diesel OilFuel for road vehicles and trains.Lubricating Oil18 to 25300 to 400Lubricant for engines and machines.Fuel Oil20 to 27350 to 450Fuel for ships and heating.Greases and Wax25 to 30400 to 500Lubricants and candles.Bitumenabove 35above 500Road surface and roofing.
6 Chemical ProcessingThe fractions from crude oil are liable to undergo chemical processing to alter its structure and thus its propertiesThe sort of chemical processing employed depends largely on the market demandExamples of chemical processes are as the following:Cracking: the process obtaining relatively simple and small hydrocarbon molecules from the breaking down of large, heavier and more complex hydrocarbon molecules.Coking: the process of breaking down bitumen into its fractions (done by a Coker)Alkylation: A process where the structure of a hydrocarbon molecule in one fraction is altered to produce another hydrocarbon molecule with another structure. In alkylation, compounds with a low molecular weight, such as propylene and butylene, are mixed in the presence of a catalyst such as hydrofluoric acid or sulfuric acidUnification: a process where two or more hydrocarbons are combined to produce a larger one. The major unification process is called catalytic reforming and occurs in the presence of a catalyst (platinum, platinum-rhenium mix) to combine low weight naphtha into aromatics
7 Treatment ProcessesChemical sweetening, acid treating, clay contacting, caustic washing, hydro treating, drying, solvent extraction, and solvent dewaxing. Sweetening compounds and acids desulphurize crude oil before processing and treat products during and after processing.Clay TreatingUse clay to soak up and remove unwanted components in petroleumDilute the oil with solvent and freeze the oilDuring the freezing process, wax will be solidify leaving only the pure oil in liquid phaseAcid treatingUsing concentrated sulphuric acid to convert sludge from the oilExpensiveSO2 TreatingUsing a very toxic recyclable solvent to remove the worst components in oil
8 Treatment: The Finishing Touch Impurities such as organic compounds containing sulphur, nitrogen, oxygen, water, dissolved metals and inorganic salts must be removed from the distillated and chemically processed fractionsTreating is typically done by passing the fractions through the following:a column of sulphuric acid - removes unsaturated hydrocarbons (hydrocarbons with carbon-carbon double-bonds), nitrogen compounds, oxygen compounds and residual solids (tars, asphalt)an absorption column filled with drying agents to dehydrate the fractionsulphur treatment and hydrogen-sulphide scrubbers to remove sulphur and sulphur compoundsToday, a major portion of refining involves blending, purifying, fine-tuning and improving products to meet specific requirementsExample: Refinery workers carefully blend together a variety of hydrocarbons to make petrol. Moreover to distinguish the various grades of fuel, technicians add performance additives and dyes. At the end of the production of petrol, the petrol contains more than 200 hydrocarbons and additives
10 Why Upgrade An Oil Refinery? Oil refining releases carbon dioxide into the atmosphereResponse to changing market demands for certain productsGovernment regulationsClean Air Act Amendments of 1990 (CAAA90)Changing consumer demand for better and different productsDecrease the number of non-hydrocarbons, impurities, and other constituentsPotential physical, mechanical, chemical, and health hazards are recognized in air
11 Accomplishment of Oil Refinery Upgrading The emissions of pollutants from oil refining decreased significantly over the past decade due to the new technology implemented into the oil refining techniques
12 Solvent-Refining Process Uses chemicals (fairly safe recyclable solvent) to dissolve one part of the oil from anotherRemoves heavy materials and wax (undesirable component by extraction)
13 ReferencesHow Stuff Works How Oil Refining Works?. [Online].UTS Energy Corporation Glossary. [Online]Products of Oil. [Online]Alan G. Lucas Modern Petroleum Technology Volume 2. New York: John Wiley & Sons Inc.Douglas M. Ruthren Encyclopaedia of Separation Technology Volume 2. New York: John Wiley & Sons Inc.