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Cruel oil, another word is petroleum, is unprocessed oil, the thing which comes from the ground. Crude oil is a fossil fuel and was produced from decaying plants or animals living millions years ago in seas in nature, mostly in sea beds (EnergyAPI. 2009). Crude oils have different colour, ranging from clear to tar black. It has various viscosity as well, from water to almost solid. It is a very useful pioneer for many various substances as they have hydrocarbons. They are molecules that consist of carbon and hydrogen and come from different length and structure, straight chains, branch chains or rings.
The issue with crude oil is it contains hundreds of various types of hydrocarbons gathered together (Earth Science from Mourland School. 2009). Different kinds of hydrocarbons have to be separated to make something useful, which is very important to our daily life. Oil refining is an easy way to achieve it.
Crude oil is very important to our daily life, list of following products are produced. "
" (Freudenrich,C. 2009)
The crude oil industry consists of the global processes and marketing crude oil products. The greatest volume products in crude oil industry are fuel oil and petrol. Crude oil is the pioneer for many chemical products, such as solvents, fertilizers, pharmaceuticals, plastics and pesticides (Earth Science from Mourland School. 2009).
The petroleum industry is basically divided into three major constitutents: Upstream, midstream and downstream (Petroleum Association of Canada. 2010). Midstream operations are included in the category of the downstream.
The upstream sector is referred to as exploration and production sector. The processes are in looking for underground or underwater oil and gas fields and drilling exploratory wells. Also, at the same time, operate the wells that recover to redirect the crude oil or raw natural gas to the surface.
Processing, storing, marketing and transporting crude oil, natural gas and a variety of natural gas liquids such as ethane, butane and propane are known as the midstream sector.
Downstream refers to the supply of oil products from their production at refineries to their final consumption by users, which includes marketing, customer service and strategic planning for the sale and delivery of finished products (Petroleum Association of Canada. 2010). Those products are included. For example, liquified petroleum gas (LPG), gasoline or petrol, jet fuel, diesel oil,heating oil, lubricants, natural gas, propane, etc.
(Downstream Oil, 2010)
Crude oil is transferred through pipeline from upstream operations and is changed into some functional forms such as gasoline, diesel, jet fuel and even antifreeze and propane during the process of oil refineries (Downstream Oil, 2010).
The duties in the downstream sector include process hazard analysts, plant operators, maintenance supervisors, tax accountants, contracts managers and instrument engineers.
The Refining Process:
A barrel of crude oil is made up of a mixture of hydrocarbon. Useful substances are separated by oil refining. Generally, chemists make use of the following steps:
First, the mixture of two or more liquid substances with different boiling temperature is heated to a high temperature (Freudenrich,C. 2009).The process is done with high pressure stream to about 600Â°C.Then the mixture is boiled and vapour formed as most substances go into vapour phase. After that, the vapour goes into the lowest part of the long fractional distillation column which is filled with plates (Freudenrich,C. 2009). Many holes are in the plates so vapour is allowed to pass through. Also, the contact time between the vapour and liquids in column are increased in plates. It helps to receive liquids that form at different heights in the column. The difference of temperature across the column as a result. The cooler is at the top, hotter at the bottom. The vapour goes up in the column and is cooled when it rises through the plates in the column. The substance in the vapour will condense to develop a liquid when it arrives at a height which the temperature of the column is as same as its boiling temperature. The substance which has lower boiling point will condense in higher point, whereas the substance with higher boiling point will condense in lower column. Then, the plates collect the different liquid fractions. The gathered liquid fractions may pass to condensers which can further cool them and then go to the storage tanks, or else go to additional parts for further chemical processing.
Three ways, which are cracking, unification, and alteration are provided to change one fraction into another (Earth Science from Mourland School. 2009).
For cracking, it is the breaking of large hydrocarbons into smaller ones. There are a number of types, including thermal, steam, visbreaking and coking (Freudenrich,C. 2009).
Thermal means heating heavy hydrocarbons at high temperatures and high pressure (if necessary) until they break (Earth Science from Mourland School. 2009). For steam, it means high temperature (816Â°C) steaming, which is operated to break ethane, butane and naptha into ethylene and benzene (Freudenrich,C. 2009). In the case of visbreaking, heat residual from the distillation tower (482Â°C), then cooled with gas oil and quickly burnt in a distillation tower. This process can lower the viscosity of heavy oils and give out tar.
For coking, heat the residual from the distillation tower. The temperature must be higher than 482Â°C so it cracks into weighty oil, gasoline and naphtha (Freudenrich,C. 2009). When the process has been finished, a weighty, nearly pure carbon residue, which is the coke, is left behind. Coke will be cleaned by the cokers and sold.
In order to accelerate the cracking reaction, catalysts are operated, which consist of aluminum, bauxite, hydrosilicate, silica-alumina and zeolite (Freudenrich,C. 2009).
Catalytic cracking includes fluid catalytic cracking and hydrocracking. The former one is a hot, fluid catalyst (538Â°C) breaks heavy gas oil into diesel oils and gasoline (Freudenrich,C. 2009). Hydrocracking is as like as fluid catalytic cracking. Nevertheless, it uses a different catalyst, which is lower in temperatures, higher in pressure, and hydrogen gas is used. It obtains weighty oil and cracks it into gasoline and kerosene.
After different hydrocarbons are cracked into smaller ones, the products use different fractional distillation column to take apart them (Earth Science from Mourland School. 2009).
Catalytic reforming (Freudenrich,C. 2009)
For Unification, it is the combination of smaller hydrobons to make larger pieces (Freudenrich,C. 2009).
The main unification process which known as catalytic reforming use catalyst to combine light naphtha into aromatics, that are operated to create chemicals and blend gasoline (Freudenrich,C. 2009). Hydrogen gas is a crucial by-product of this reaction and it is used for hydrocracking or sold.
Alkylation (Freudenrich,C. 2009)
Alteration is the rearrangement of different pieces of hydrocarbons to make other hydrocarbons.
It is made by a process called alkylation (Freudenrich,C. 2009). Low molecular weight compounds, for example, propylene, is combined in the presence of a catalyst like sulfuric acid. Alkylation which is the product is high octane hydrocarbons. This can be operated in gasoline blends to lower the possibility of knocking.
Treating and Blending the Fractions:
Impurities need to be removed by treating with distillated and chemically processed fractions. For instances, organic compounds containing nitrogen, oxygen, sulphur, water, dissolved metals and inorganic salts (Earth Science from Mourland School, 2009). The treating process is regularly operated by passing the fractions through a column of sulphuric acid. Sulphuric acid is used to take away unsaturated hydrocarbons, nitrogen compounds, oxygen compounds and residual solid, such as tars and asphalt (Freudenrich,C. 2009). Another one is an absorption column filled with dehydrating agents which is to remove water. The last one is sulphur treatment and hydrogen-sulphide scrubbers to remove sulphur and sulphur compounds.
After the treating process, they are cooled and blended to produce different products. For example, gasoline and kerosene of different grades, jet fuel, diesel fuel, heating oil and chemicals of different grades so as to make plastics and other polymers (Freudenrich,C. 2009).
For marketing, the goal is to inform customers that a product exists in which will improve the quality of their living standard. This is not difficult in the United States, which is the crude oil's largest market. In 2004 alone, more than seven million cars were sold. Gasoline is the way to power cars and with high car sales, marketing executives at oil companies do not have any problem in selling their products. For example, BP Amoco which is a world leader in petroleum production stated that their sales are over $274 billion in 2006 (Downstream Oil, 2010).
To synthesize crude oil into applicable products, it must first be processed. The refining process for crude oil follows a controlled process.
Fractions distillation is a traditional and general method to separate things into a variety of components through their different boiling point. Heat the crude oil and it will vaporize and finally condense the vapour.
Chemical processing is the latest technique to make fractions to others by a process called conversion. It can break long chains into short chains. This can let a refinery change diesel fuel into gasoline depending on the need of gasoline. To take away impurities, fractions must be treated by refineries. It combines different fractions, no matter processed or unprocessed, into mixtures to create preferred products, such as different mixtures of chains, which can produce gasoline with various octane ratings.