for the writer

Purpose

Oil refinery is one of the industries that has a lot of dangerous actions might happen and make the workers’ life in risk. Working in big industry such as, oil refinery, attract workers and make them blind of thinking about the bad side of these industries. The purpose of report is to make an assessment of the effects on workers who work inside oil refineries, those people who deal with huge complex machines and of course with various types of chemical component inside oil refineries. This report will discuss the history of crude oil, and how the crude oil is transport to the oil refineries. Introduce the variety types of oil refineries and the major of these refineries. It will discuss different ways of processing the crude oil to be useful and will introduce chemical component that is found during processing oil and the risk of facing these chemical component on workers. It will discuss physical injuries and problem might oil refineries face. This report will discuss as well environmental laws that affected this nature. At the end of this report will it with solutions that might be possible to apply.

History of Crude oil ( Petroleum)

Crude oil is a liquid contains of Hydrocarbons (carbon 84 % and hydrogen 14 %) , organic compounds ( sulfur 1 to 3 % , Nitrogen less than 1%, and Oxygen less than 1 %) , small amounts of metal ( usually less than 1 %) ,and less than 1% of salts. As the percent shows that Hydrocarbons consider being the primary component of the crude oil. Crude oil vary in color from tar-black to almost solid ( see figure 1 ).

Organic materials combined with mud and then because of the high-level pressure lead to high temperature in the bottom of the earth, ocean, or lake, these organic materials will form what is called crude oil. Today, most of the extracted crude oil is about prehistoric algae and zooplankton, whose are settled on the bottom of ocean a long time ago. Through this process (digenesis) these organic materials will change the chemical composition first into waxy compounds ( kerogen) and after that to because of the high level of heating will change it into a liquid ( catagenesis).

Before extracting the crude oil from the ground Geologist test a section of land that they think has oil. Satellite imagery, gravity meters, and magnetometers are three of the ways that geologist might use to predict if the there is oil or not at a land.

Drilling is the most common method of extracting crude oil from the ground and it is developed by standard method. First, drilling into the ground in the place where oil is located. When the steady flow identify by certain depth beneath the ground a perforating gun is lowered into the well. This perforating gun has charges, which allow for oil flow through holes in the casing. The tube is run to the hole, which allow oil and gas to flow up the well. The last step is about the placement of the structure, which called the Christmas tree, this allow controlling the flow of oil from the well.

Crude oil transport to the refineries across water and that is by barges and tankers, or across land by pipelines, trucks, and trains.

Table 1: shows prices for the different ways of transporting crude oil to the refineries.

Oil refineries

These are two types of oil refineries.

-Petroleum oil refinery is the place where the worthless conform to worth full, where the crude oil converts into high-octane motor fuel (gasoline), diesel oil, liquefied petroleum gases (LPG), jet aircraft fuel, kerosene, heating fuel oils, lubricating oils, asphalt, and petroleum coke.

- Natural gas processing plant is where convert natural gas into residential, commercial and industrial fuel gas, and also recovers natural gas liquid, ethane, propane, butane, and pentanes.

Processing crude oil in refineries

Figure 1

The main goal of oil refineries is to separate valuable distillates naphtha, kerosene, diesel, and atmospheric gas oil from crude oil. The final result of the processing has totally different characteristics than the crude oil. Before processing workers make sure to remove the substances that might damage engine or other machinery. Figure 1 illustrates the process of oil refineries. The first and most common way is fractions way, which separate things into various groups of hydrocarbons that boil between two specified boiling points.

There are two steps of distillation are performed Atmospheric and Vacuum. First, Atmospheric distillation is about heating up the crude oil to about 350° to 400° Celsius and let it vaporize and then condense the vapor and that is in fractioning tower. The vaporized oil rises up the tower through a series of sieves trays. As result heavier hydrocarbons fall more quickly and settle on the lower layers and lighter hydrocarbons will be on the upper trays because it remain as vapor longer. Methane, ethane, propane, and butane are light gasses, which pass out the top of the column. Petrol is going to be located on the top trays. Kerosene and gas oil are in the middle. Fuel oils is located at the bottom.

Vacuum distillation is the second step of the fractions way. This step is to recover additional heavy distillates from this residue. This step is going to be piped to a second distillation and this process is going to be done under vacuum. Then , through Solvent extraction the heavier distillates recovered by vacuum distillation can be converted into

Lubricating oils. It is about washing the heavy distillate with a liquid that cause the non-lubricating oil component to precipitate from it. Figure 1 shows the different temperatures for some products.

Figure:1

Reforming is about using heat, pressure, and catalyst (most of the time platinum) to allow chemical reactions and that upgrade naphthas into high-octane petrol and petrochemical feedstock. Naphthas are just hydrocarbons contains of many paraffins and naphthenes. Through this process a portion of compounds is going to be converted to isoparaffins and aromatics, and these are used to blend higher-octane petrol. So, the result of this process is paraffins are going to be converted to isoparaffins and naphthenes. Then Naphthenes are going to be converted to aromatics.

Then, cracking step is containing of four steps catalytic cracking, Fluid catalytic cracking, thermal cracking, and hedrocracking. First, through cracking process, the heavier hydrocarbon molecules (high boiling point oil) are going to be breaking into lighter product, such as, petrol and diesel. By catalytic cracking, Heavy hydrocarbons fractions obtained from vacuum distillation is going to be converted to mixture of more useful products, like, light fuel oil, and this process is going to be done under controlled pressure, heat about 450° to 500° C, and in the presence of a catalyst that is a substance which promotes the reaction without itself being chemically changed. Second, Fluid catalytic cracking uses a catalyst in the form of a very powder and that flows like a liquid when agitated by steam, air or vapor. Feedstock get the process meets a stream of very hot catalyst and vaporizes. Then vapors have the catalyst fluidized like it passes into the reactor, which the cracking takes place and where it is fluidized by the hydrocarbon vapor. Then catalyst passes to stream stripping section, where most of the volatile hydrocarbons are removed. After that, it is going to be passes to a regenerator vessel where it is fluidized by a mixture of air and the products of combustion which are produced as the coke on the catalyst is burnt off. Then, the catalyst flows back to the reactor. The catalyst most of the time is about mixture of aluminum oxide and silica. Third, Thermal cracking is about breaking down the residue from vacuum distillation. Through thermal cracking step, the lighter elements are going to be produced. By alkylation or polymerization, cracked gases are going to be converted to petrol blending components. Naphtha is upgraded to high quality petrol by reforming, and gas oil can be used as diesel fuel or can be converted to petrol by hydrocracking.

Alkylation is chemical bonding of these light molecules with isobutene to form larger branched-chain molecules (isoparaffins), which make high-octane petrol. Alkylation is responsible of producing Olefins such as propylene and butylene. Mixing Olefins and isobutuane with an acid and cooled is going to react and form alkylate, plus some normal butane, isobutane and propane. The liquid that is resulting from the reaction is neutralized and separated in series of distillation columns. Isobutane is recycled as feed and butane and propane sold as liquid petroleum gas (LPG).

Isomerization is chemical rearrangement of straight-chain hydrocarbons (paraffins), and it can be used to improve petrol quality by converting these hydrocarbons to higher-octane isomers. This is important to create extra isobutene feed for alkylation and to improve the octane of straight run pentanes and hexanes.

Polymerisatio is completed under pressure and temperature, aver an acidic catalyst, light unsaturated hydrocarbon molecules react and combine with each other to form larger hydrocarbon molecules.

Hydrotreating and sulphur plants

Damage the equipment can be happened as the fractions travel through the refinery processing units. It affects as well the catalysts and the quality of the products. There are legal limits on the contents of some impurities in products, such as, sulphur. Hydrotreating is a way used to remove the contaminants from intermediate or final products. Through this way the entering feedstock is mixed with hydrogen and heated to 300 - 380oC. Oil is mixed with hydrogen then enters a reactor loaded with catalyst which leads to many reactions:

· hydrogen combines with sulphur to form hydrogen sulphide (H2S)

· nitrogen compounds are converted to ammonia

· any metals contained in the oil are deposited on the catalyst

· some of the olefins, aromatics or naphthenes become saturated with hydrogen to become paraffins and some cracking takes place, causing the creation of some methane, ethane, propane and butanes.

Sulphur recovery plants

The hydrogen sulphide is a toxic gas that created from hydrotreating process, and this gas needs to be treated. This process is involves two steps:

-Removing hydrogen sulphide gas from the hydrogen stream.

- Conversing hydrogen sulphide to elemental sulphur, a non-toxic and useful chemical.

When the gas cools, its component compress back into many liquids. Light liquid is one type of the liquids, such as, kerosene and naptha, and a heavy liquid is the other type, such as, lubricants and waxes.

The new way is using chemical processing which called conversion. Through this way the long chains can be broken to shorter one, like, diesel fuel can be turned to gasoline.

As mentioned before that the main component of the crude oil is hydrocarbons. The three main classes of hydrocarbons in crude oil are Paraffin, Aromatics, and napthenes or Cycloalkanes.