Three sources of raw materials are important for the industry: oil, gas and coal.
Oil.
Oil is a dark, oily liquid, insoluble in water, which contains branched and unbranched alkanes, cycloalkanes. The composition depends on the field.
Oil is the main material for the production of organic compounds by dry distillation (pyrolysis, carbonization). The main products are aromatic hydrocarbons and their derivatives. Mainly dyes, synthetic fats and oils are obtained.
With the growing importance of oil, methods of chemical processing have improved. Currently, about 90% of synthetic organic compounds are obtained from petroleum and its derivatives.
Laboratory and industrial methods of oil production.
There are a number of significant differences between laboratory and industrial methods of oil production, namely:
- price (in the laboratory, small quantities of reagents are used, when, as in industry, large volumes are needed. Therefore, expensive and rare compounds can be used in the laboratory, and in industry you need to get by at the lowest cost. Or the use of harmful toxic substances in the laboratory is quite acceptable due to the presence of fume hoods , then on an industrial scale it is extremely dangerous.);
- warmly. In industry, the supply of heat is very expensive for reactions carried out at moderately high and normal temperatures, when, as for a laboratory, such syntheses are easy to carry out;
- the purity of the mixture. In the laboratory, they usually work with pure substances, while in industry, mainly with mixtures;
- circulation of substances. If in industry it is possible to separate mixtures by various chemical processes (distillation, filtration, continuous processes), then for the laboratory it is unprofitable. In industry, there is a cyclical nature of processes, when an unreacted substance can be reintroduced into the cycle of the processing process, but in a laboratory this is done with great difficulty.
Oil refining.
In industry, fractional distillation of "crude oil" is used, as a result of which the latter is divided into several fractions that have different boiling points:
Gasoline fraction consists of petroleum ether and extraction gasoline. The composition of the fraction varies from C 6 - C 9. The entire fraction is a weighty oil product, because serves as fuel for internal combustion engines.
Kerosene (C 9 -C 16) it is used in heating devices and is also a fuel for aircraft and turbine engines.
Gas oil (diesel) serves as fuel for diesel engines.
Lubricating oils (C 20 - C 50) used as lubricants.
Fuel oil (residue) - used as a fuel, it is distilled, resulting in a high-boiling hydrocarbon fraction.
Chemical transformations of hydrocarbons contained in oil.
The importance of fuel in the modern world is growing significantly. It is for this reason that the most optimal way to obtain gasoline from high-boiling fractions has been found - cracking - heating higher alkanes without access to air, as a result of which decomposition into lower and higher hydrocarbons occurs:
If cracking proceeds without the use of a catalyst, then it is called thermal. If the catalyst is used SiO 2 or Al 2 O 3 then it is catalytic cracking. The products of such processes are ethane and propene, which have become important raw materials for industry.
To improve the quality of gasoline, reforming and alkylation are carried out.
Reforming (isomerization) - a process in which unbranched alkanes, when heated with a catalyst, are converted into more branched alkanes with a higher octane number. For instance,
Alkylation - a process in which a mixture of alkanes and alkenes is converted into branched compounds with a high octane number, when using an acid as a catalyst:
Natural gas.
Natural gas is a set of gases, the composition of which depends on the field. Basically, it is a mixture of methane, ethane and propane, but small amounts of nitrogen, higher alkanes, carbon, helium (rarely) can still be found.
Natural gas is an industrial fuel, the most important compound is synthesis gas (mixture of carbon monoxide and hydrogen):
It can be obtained by the action of incandescent coke with water vapor; the compound obtained in this process is called water gas:
It is from carbon monoxide and hydrogen that methanol is obtained:
The reaction takes place under pressure in the presence of catalysts.
Coal.
Bituminous coal serves as a raw material for the production of aromatic hydrocarbons. The process can be schematically represented as follows:
Toluene can be obtained in a similar way.
Dry distillation at high temperatures produces a mixture of solid, liquid and gaseous products.
Gas-phase product is an coke oven gas, the main component of which is hydrogen and methane.
Liquid product represents tar, from which a large amount of phenol, cresol, naphthalene, thiophene, anthracene is isolated.
Solid product is an coke.
Reflections about what awaits us in the future and before did not give rest to scientists. Today, everyone is talking about this topic: from government leaders to schoolchildren. Global warming, melting of age-old ice, demographic problems, human cloning, modern and future means of communication and transportation, people's dependence on energy resources ... And yet one of the most popular topics today is the issue of alternative fuels.
Fuel of the future - an alternative to natural resources
Natural fuels are currently our main source of energy. Hydrocarbons are burned to break down molecular bonds and release their energy. The high consumption of fossil fuels results in significant environmental pollution when they are burned.
We live in the 21st century, this is a time of new technologies, and many scientists believe that the time has come to create an alternative fuel of the future that can replace traditional fuels and eliminate our dependence on it. Over the past 150 years, the use of hydrocarbons has increased the amount of carbon dioxide in the atmosphere by 25%. Burning hydrocarbons also leads to other types of pollution such as smog, acid rain and air pollution. This type of pollution not only harms the environment, animal and human health, but also leads to wars, as fossil fuels are not renewable resources and will eventually run out. At the moment, it is important to find new solutions and establish alternative fuel sources for the future.
While some scientists are solving the issue of increasing the oil recovery factor of productive formations, while others are looking for ways to obtain gaseous fuel from oil shale, others have come to the conclusion that the need for fuel can be satisfied by the usual old-fashioned method. We are talking about "solid petroleum products", natural fuel - wood. The idea of \u200b\u200b"as old as the world" was taken up by specialists from Stanford University in the USA, and scientists from the University of Georgia joined them. Of course, special fast-growing varieties of trees such as alder or plane trees are needed, which yield up to 40 tons of wood per hectare per year.
Platanus - Platanus - a powerful tree with a dense spreading crown and thick trunk - the ancestor of the vast family of plane trees. There are about 10 species of plane trees in all. The height of the plane tree reaches 60m, and the circumference of the trunk is up to 18m! The trunk of the sycamore is even cylindrical, the bark is greenish-gray, flaking. The leaves of the sycamore are palmate-lobed, with elongated petioles.
After cutting down plane trees, foliage remains on the ground, which can be used for natural fertilization. Plane wood is crushed in crushers and fed into the furnace of power plants. The 125 km2 plane tree plantation site can provide energy to a city with a population of 80 thousand people. On the felled areas, in 2-4 years, new sycamore trees will grow from the shoots, suitable for fuel. Scientists have calculated that if 3% of the territory of Russia and Ukraine is allocated for "energy plantations of plane trees" for growing natural fuel, then the countries could fully satisfy their fuel needs at the expense of firewood.
The main advantage of using "grown fossil fuels", as opposed to "fossil fuels" (coal, natural gas and oil), is that as it grows, the sycamore energy forest absorbs carbon dioxide, which is later released when it burns. This means that when plane trees are burned, the same amount of CO2 is emitted into the atmosphere, which was absorbed by the plane tree during its growth. By burning fossil fuels, we increase the content of CO2 in the atmosphere, and this is the main reason for global warming.
The new fuel holds promise as a valuable renewable energy source and will become more important in the future. Already today, for example, Europe's largest plane tree power plant is located in Simmering (Austria). Its capacity is 66 MW, with an annual consumption of 190 thousand tons of sycamore grown here within a radius of 100 km. And in Germany, the capacity of energy forests reaches 20 million cubic meters of wood per year.
New fuels
American supporters of the “wood-burning” of household heat power engineering are echoed by their colleagues from Europe In Belgium, for example, in 1988 the newspaper “Saar” published an article where it called wood the natural fuel of the future, as an alternative to the use of petroleum products. For the same purposes, it is proposed to use waste paper. There, stores already sell a manual press for making briquettes from waste paper, which is not inferior in caloric value to brown coal.
You can also buy special economical furnaces that work on the principle of a gas generator, the design of which prevents heat from escaping through the chimney. Firewood and waste paper briquettes burn very slowly in this oven: bundle - in 8 hours. In this case, the firewood burns completely, there is no release of ash and soot into the atmosphere. Heating the premises with such stoves is very beneficial, because a kilogram of firewood with a comparable calorific value costs 10 times less than a liter of liquid fuel, for storage of which special fuel containers are also required.
Another group of American scientists was attracted by fast-growing brown algae. Marine plantations are proposed to be processed into methane gas using bacteria. It is also possible to obtain oil-like substances by heating. According to calculations, a natural farm in the ocean with a plantation area of \u200b\u200b40 thousand hectares will be able to supply energy in the future to a city with a population of 50 thousand people. Scientists from France suggest using unicellular algae as an alternative fuel. It turns out that these microscopic organisms release hydrocarbons in the course of their life. By growing algae in special containers and supplying them with carbon dioxide and mineral salts, you can regularly "harvest hydrocarbons" and get natural fuel.
Natural natural "gas stations" are found in the tropics of South America, the Philippines. Some types of vines and tropical trees contain natural fuel - "diesel fuel", which does not even need to be distilled. Alternative fuel from vines burns well in car engines, giving less toxic exhaust than gasoline Suitable for the production of fuel and palm oil, from which it is relatively easy to obtain "diesel fuel".
But for now this is all in the realm of science fiction. A more realistic project is to obtain synthetic fuel from charcoal. A fairly simple method developed by US scientists. The coal is crushed, treated with a solvent, and hydrogen is added to the resulting mixture. From a ton of coal, almost 650 liters of synthetic fuel are obtained, from which synthetic gasoline can be produced.
US scientists are seriously engaged in underground gasification of coal seams. By the pyrolysis method, 40% of methane gas, 45% of coke and 3% of liquid fuel are obtained from it. Experts have developed a completely unexpected way to get the fuel of the future ... from garbage. Magnetic and non-magnetic metals are preliminarily extracted from human waste, which are then sent to be melted down. The new technology for recycling glass waste makes it possible to obtain glass from fragments that is cheaper and of higher quality than the initial raw materials. Waste residues are processed into coke, methane gas and liquid fuel. "Garbage" petroleum products were tested on pilot plants - they burn perfectly. From a ton of garbage in this way they "extract" from 6 to 20 dollars. 1976 - 1977 in San Diego, a special waste recycling plant went into operation.
However, a similar problem is being successfully addressed in the UK. A garbage processing unit has been developed and is currently operating here, in which, under the influence of high temperatures during the combustion of blown oxygen from garbage (plastic packaging and bottles, food waste, scraps of newspaper, rags, etc.), synthetic oil products and methane gas with hydrogen are obtained ... Liquid synthetic fuels and gas are supposed to be stored in tanks and used partly for diesel operation and partly for melting broken glass from which building blocks can be obtained. In the future, it is planned to process waste in old blast furnaces. This will give high productivity, saving time and money for the construction of new incineration plants. As experiments have shown, the remaining slag will also be used - it is suitable for replacing gravel when performing concrete work.
And here are two more ways to get synthetic gasoline. French engineer A. Rothlisberger obtained alternative gasoline from dry corn stalks. The author argues that the new fuel of the future with an octane number of 98 can be extracted from straw, sawdust, vegetable tops and other waste containing cellulose fibers. Under pressure from government agencies, the inventor classified the technology for the synthesis of new fuel, but it is known that the quality of new gasoline largely depends on complex stabilizing additives introduced into alcohols and isopropynyl ethers obtained from cellulose. New alternative fuel does not detonate, burns without smoke and odors. It can be mixed in any proportion with regular gasoline. At the same time, in the future, design changes in the engines are not required. France intends to eventually bring the production of new gasoline to 20 million tons per year.
Another inventor of artificial gasoline lives in Switzerland. The starting material is wood chips, corn husks, plastic bags. But the trouble is, "gasoline of the future" smells like moonshine. The inventor has to pay 8% tax as for the production of alcoholic beverages. Nevertheless, 1 liter of artificial "gasoline of the future" costs 2 times cheaper than the present one, and the car works as good as new.
The inventions of the inventors are not limited only to artificial gasoline; they offer original methods of producing hydrocarbon gas for domestic purposes. One of which is developed in Germany. The garbage dump in the suburban town of Schwerborn is a new source of alternative energy for the future. When filling the landfill, a network of gas wells and pipelines was laid under it. It turns out that 1 kg of garbage gives up to 200 liters of gas, of which 100 liters is methane. So far, 40 m3 of gas is "extracted" at the landfill per hour.
The new fuel heats production facilities. It is planned to build a heating plant using an alternative fuel for heating the village. According to calculations, the cost of obtaining an alternative fuel will pay off in 3.5 years.
The second way is even more unexpected. The proposal was made by the authorities of Ottapalam in Kerala (India). The recipe for the new fuel is as follows: The well is filled with cow dung and hermetically closed. The gas generated during fermentation is led through connected pipes to gas stoves in houses. Such a biogas plant fully satisfies a family's need for bioenergy for home use. Today, 53 models of biogas systems have been developed and applied in India. They are effectively used by about 3.5 million families. The country's government actively supports the expansion of biogas plants. Already, this is saving about 1.2 billion rupees a year.
Solar energy is the technology of the future
At the beginning of this article, we mentioned various new energy technologies. Photovoltaic systems (or solar cells) are another “technology of the future” already in use today.
Many people now use solar panels as the main or backup source of electricity for homes and office buildings. If you have been to the sea recently, you may have noticed that solar energy is also used in navigation buoys. They have long been "adopted" by the military: during Operation Desert Storm, field radios were equipped with lightweight ECD solar panels.
In the future, the use of solar panels will only grow. Recently, ECD, in collaboration with Texaco, proposed solar technology to power oil production equipment in a 200-hectare oil field in Bakersfield, California. Previously, to produce three barrels of oil, one was burned in a steam generator. The use of solar energy will not only reduce the consumption of irreplaceable resources, but also reduce harmful emissions and noise.
Fossil fuels are oil, bituminous coal, oil shale, natural gas and its hydrates, peat and other combustible minerals and substances from the caustobiolith group, used mainly as fuel, extracted underground or by open pit mining. Fossil fuels are formed from the fossilized remains of dead plants by decomposition under anaerobic conditions under the influence of heat and pressure in the earth's crust over millions of years. Coal and peat are fuels formed as animal and plant remains accumulate and decompose. Fossil fuels are a non-renewable natural resource as they have been accumulating for millions of years. According to the Energy Information Administration, in 2007 the primary energy sources used were oil - 36.0%, coal - 27.4%, natural gas - 23.0%, in total the share of fossil fuels accounted for 86.4% of all sources (fossil and non-fossil) of consumed primary energy in the world. It should be noted that the composition of non-fossil energy sources includes: hydroelectric power plants - 6.3%, nuclear - 8.5%, and others (geothermal, solar, tidal, wind energy, wood burning and waste) in the amount of 0.9%.
Oil (Greek ναφθα, or through Tur. Neft, from Persian oil; goes back to Akkad.napatum - to flare up, ignite) is a natural oily flammable liquid, consisting of a complex mixture of hydrocarbons and some other organic compounds. The color of the oil is red-brown, sometimes almost black, although sometimes there is also a weakly colored yellow-green and even colorless oil; has a specific smell, is common in sedimentary rocks of the Earth. Oil has been known to mankind since ancient times. However, today oil is one of the most important minerals for mankind.
Coal is a type of fossil fuel formed from parts of ancient plants underground without oxygen. The international name for carbon comes from lat. carbō (coal). Coal was the first fossil fuel used by humans. He allowed the industrial revolution to take place, which in turn contributed to the development of the coal industry by providing it with more modern technology. Coal, like oil and gas, is an organic matter that has been slowly decomposed by biological and geological processes. The basis of coal formation is plant residues. Depending on the degree of conversion and the specific amount of carbon in coal, four types are distinguished:
brown coals (lignites); coal; anthracites; graphites.
In Western countries, there is a slightly different classification - lignites, subbituminous coals, bituminous coals, anthracites and graphites, respectively.
Oil shale is a mineral from the group of solid caustobiolites, which, during dry distillation, gives a significant amount of resin (close in composition to oil). Shales were mainly formed 450 million years ago at the bottom of the sea from plant and animal remains. Oil shale consists of the predominant mineral (calcite, dolomite, hydromica, montmorillonite, kaolinite, feldspars, quartz, pyrite and others) and organic parts (kerogen), the latter makes up 10-30% of the mass of the rock and only in shale of the highest quality reaches 50-70%. The organic part is the bio- and geochemically transformed substance of the simplest algae, which retained the cellular structure (thallomoalginite) or lost it (colloalginite); altered remains of higher plants (vitrinite, fusenite, lipoidinite) are present in the organic part as an impurity.
Natural gas is a mixture of gases formed in the bowels of the earth during the anaerobic decomposition of organic substances. Refers to minerals. Natural gas in reservoir conditions (conditions of occurrence in the earth's interior) is in a gaseous state - in the form of separate accumulations (gas deposits) or in the form of a gas cap of oil and gas fields, or in a dissolved state in oil or water. Under standard conditions (101.325 kPa and 20 ° C), natural gas is only gaseous. Also, natural gas can be in a crystalline state in the form of natural gas hydrates.
Gas hydrates (also hydrates of natural gases or clathrates) are crystalline compounds formed under certain thermobaric conditions from water and gas. The name "clathrates" (from Latin clathratus - "to plant in a cage") was given by Powell in 1948. Gas hydrates are classified as non-stoichiometric compounds, that is, compounds of variable composition.
Shale gas is a natural gas produced from oil shale and consists mainly of methane.
Peat (German Torf) is a combustible mineral; formed by the accumulation of plant remains that have undergone incomplete decomposition in swamp conditions. Contains 50-60% carbon. Heat of combustion (maximum) - 24 MJ / kg. It is used in an integrated manner as fuel, fertilizer, heat-insulating material, and so on. The bog is characterized by the deposition of incompletely decomposed organic matter on the soil surface, which later turns into peat. A layer of peat in swamps is at least 30 cm (if less, then these are swampy lands).
Fossil fuels contain a high percentage of carbon and include fossil coal, oil and natural gas. In turn, oil, gas, and fossil coal were formed from the deposits of once living organisms under the influence of high temperature, pressure and anaerobic decomposition of dead organisms buried under the layer of sedimentary rocks. The age of organisms, depending on the type of fossil fuel, is usually millions of years, and sometimes exceeds 650 million years. More than 80% of the oil and gas that is currently in use formed in layers that formed in the Mesozoic and Tertiary periods between 180 and 30 million years ago from marine microorganisms that accumulated as sedimentary rocks on the seabed.
The main constituents of oil and gas were formed at a time when organic residues were not yet completely oxidized, and carbon, hydrocarbons and similar components were present in small quantities. Sedimentary rocks covered the remains of these substances. Temperature and pressure increased and liquid hydrocarbon accumulated in the rock cavities.
There is an alternative hypothesis regarding the origin of oil and natural gas, which attempts to explain the formation of some anomalous oil deposits.
Oil production is a sub-branch of the oil industry, a branch of the economy engaged in the extraction of a natural mineral - oil. Excavations on the banks of the Euphrates established the existence of an oil field for 6,000-4,000 years BC. It was used as a fuel, and petroleum bitumen was used in construction and road construction. Oil was also known in ancient Egypt, where it was used to embalm the dead. Despite the fact that, starting from the 18th century, there were separate attempts to refine oil, nevertheless, until the second half of the 19th century, it was used mainly in natural form. However, oil attracted close attention to itself only after it was proved in Russia by the factory practice of the Dubinin brothers (since 1823), and in America by the chemist B. Silliman (1855) that kerosene can be isolated from it - a lighting oil similar to photogen, which at that time became widespread and was produced from some types of coal and shale. This was facilitated by a new method of oil production developed in the middle of the 19th century using boreholes instead of wells (mines). The first (exploration) oil well was drilled industrially on the Apsheron Peninsula in 1847, the first production well was drilled on the river. Kudako in the Kuban in 1864. In the USA, the first well was drilled in 1859. When developing oil fields, fresh water is pumped into the reservoir (to maintain pressure in the reservoir), including in a mixture with associated petroleum gas (water-gas stimulation) or various chemicals to increase oil recovery and combat water cut in producing wells. Due to the fact that oil reserves on land are being depleted, further improvement of the technology of the extractive sub-branch of the oil industry has made it possible to start developing oil fields on the continental shelf using oil platforms.
For the extraction of coal from great depths, mines have long been used by mankind. The deepest mines in the Russian Federation produce coal from a depth of just over 1,200 meters. Along with coal, coal-bearing deposits contain many types of geo-resources of consumer value. These include host rocks as raw materials for the construction industry, groundwater, coal bed methane, rare and trace elements, including valuable metals and their compounds. The use of jets as a destruction tool in the executive bodies of shearers and roadheaders is of particular interest. At the same time, there is a constant growth in the development of technology and technology for the destruction of coal, rocks by high-speed jets of continuous, pulsating and impulsive action.
Coal gasification - modern gas generators have a capacity for solid fuel transformation from 60,000 m³ / h to 80,000 m³ / h. Gasification technology is developing towards increasing productivity (up to 200,000 m³ / h) and increasing efficiency (up to 90%) by increasing the temperature and pressure of this technological process (up to +2,000 ° C and 10 MPa, respectively). Experiments were carried out on underground gasification of coals, the extraction of which is economically unprofitable for various reasons.
- 165.93 KbNatural sources of hydrocarbons
Oil, gas and coal
11.11.2011
MOU PSH # 1
Otinova Valentina Andreevna 10 (4) cells
1. Oil
a) Physical properties:
fractional distillation
b) Chemical properties:
cracking, thermal, catalytic cracking
c) Receiving
d) Application
2. Gas
a) Receiving
b) Application
3. Bituminous coal
a) Bituminous coal, coking
b) Application
Conclusion
Oil
Physical properties
Oil is an oily flammable liquid with a specific
odor, usually brown with a greenish or other tinge,
sometimes almost black, very rarely colorless.
The main property of oil, which has brought them worldwide fame for exceptional
energy carriers, is their ability to emit significant
quantity of heat. Oil and its derivatives have the highest among all
types of fuels by heat of combustion. Heat of combustion of oil - 41 MJ / kg, gasoline
- 42 MJ / kg. An important indicator for oil is the boiling point,
which depends on the structure of the hydrocarbons included in the oil and
ranges from 50 to 550 ° C.
Oil, like any liquid, boils at a certain temperature and
turns into a gaseous state. Various oil components are transferred to
gaseous state at different temperatures. So, the boiling point
methane –161.5 ° С, ethane –88 ° С, butane 0.5 ° С, pentane 36.1 ° С. Light oils
boil at 50–100 ° С, heavy ones - at temperatures above 100 ° С.
Oil can be divided into its components, for this it is purified from mechanical impurities or subjected to so-called fractional distillation.
Fractional distillation - a physical method for separating a mixture of components with different boiling points.
Distillation is carried out in special installations - rectification columns, in which the cycle of condensation and evaporation of liquid substances contained in oil is repeated.
Scheme of an industrial plant for continuous distillation of oil
The distillation column receives oil heated in a tubular furnace to a temperature of 320-350 ° C. The distillation column has horizontal baffles with holes - the so-called trays, on which the oil fraction condenses.
In the process of rectification, oil is divided into the following fractions:
- Distillation gases- a mixture of low molecular weight hydrocarbons (propane, butane)
- Gasoline fraction(gasoline) hydrocarbons from C 5 H 12 - C 11 H 24
- Naphtha fraction -hydrocarbons from C 8 H 18 - C 14 H 30
- Kerosene fraction- hydrocarbons from C 12 H 26 - C 18 H 38
- Diesel fuel- hydrocarbons from C 13 H 28 - C 19 H 36
Oil distillation residue - fuel oil -contains hydrocarbons with the number of carbon atoms from 18 to 50. By distillation under reduced pressure from fuel oil, diesel oil (C 18 H 28 - C 25 H 52), lubricating oils (C 28 H 58 - C 38 H 78), petrolatum and paraffin are obtained - low-melting mixtures of solid hydrocarbons. Solid residue of fuel oil distillation - tar and products of its processing - bitumen and asphalt used for the manufacture of road surfaces.
Chemical properties
Oil is mainly composed of carbon - 79.5 - 87.5% and hydrogen -
11.0 - 14.5% of the oil mass. In addition to them, oils contain three more
element - sulfur, oxygen and nitrogen. Their total number is usually 0.5
- eight %. The following elements are found in insignificant concentrations in oils:
vanadium, nickel, iron, aluminum, copper, magnesium, barium, strontium, manganese,
chromium, cobalt, molybdenum, boron, arsenic, potassium, etc. Their total content is not
exceeds 0.02 - 0.03% by weight of oil. The specified elements form
organic and inorganic compounds that make up oil.
Oxygen and nitrogen are found in oils only in a bound state. Sulfur can
meet in a free state or be a part of hydrogen sulfide.
As a result, the resulting oil rectification products are subjected to chemical processing, including a number of complex processes. One of them - cracking petroleum products.
Cracking - thermal decomposition of petroleum products, leading to the formation of hydrocarbons with fewer carbon atoms in the molecule.
There are several types of cracking: thermal cracking, catalytic cracking, high pressure cracking, reductive cracking.
Thermal cracking
- splitting of hydrocarbon molecules with a long carbon chain into shorter ones under the action of high temperature (470-550 ° С). Alkanes decompose due to the breaking of C – C bonds (stronger C – H bonds are retained at this temperature) and alkanes and alkenes with a smaller number of carbon atoms are formed.
For instance:
C 6 H 14 C 2 H 6 + C 4 H 8
In general, this process can be expressed by the diagram:
C n H 2n + 2 C n-k H 2 (n-k) +2 + C k H 2k
In conventional thermal cracking, many low molecular weight gaseous hydrocarbons are formed, which are used as feedstock for the production of alcohols, carboxylic acids, and high molecular weight compounds (polyethylene).
Catalytic cracking occurs in the presence of catalysts, which are used as natural aluminosilicates of the composition nAl 2 O 3 * mSiO 2 at a temperature of 500 ° C. Cracking with catalysts results in hydrocarbons having a branched or closed chain of carbon atoms in the molecule.
Cracking of petroleum products proceeds at high temperatures, therefore, carbon deposits (soot) are often formed, contaminating the surface of the catalyst, which sharply reduces its activity. Removal of carbon deposits - its regeneration is the main condition for the practical implementation of catalytic cracking. The simplest way to regenerate the catalyst is to burn it, during which the carbon is oxidized with atmospheric oxygen.
Catalytic cracking is a heterogeneous process involving solid (catalyst) and gaseous (hydrocarbon vapors) substances. Heterogeneous reactions (gas - solid) proceed faster with an increase in the surface area of \u200b\u200bthe solid. Therefore, the catalyst is crushed, and its regeneration and cracking of hydrocarbons are carried out in a "fluidized bed", familiar to you from the production of sulfuric acid.
The raw material for cracking, for example, gas oil, enters the reactor (diagram). The lower part of the reactor has a smaller diameter, so the vapor flow rate of the feed is very high. The gas moving at high speed captures the catalyst particles and carries them to the upper part of the reactor, where, due to the increase in its diameter, the flow rate decreases. Under the action of gravity, the catalyst particles fall into the lower, narrower part of the reactor, from where they are again carried upward. Thus, each grain of the catalyst is in constant motion and is washed from all sides by a gaseous reagent.
Scheme of a fluidized bed catalytic cracking unit
Some catalyst grains fall into the outer, wider part of the reactor and, meeting the resistance of the gas flow, descend to the lower part, where they are picked up by the gas flow and carried away into the regenerator. The use of cracking catalysts makes it possible to somewhat increase the reaction rate, decrease its temperature, and improve the quality of cracking products.
The resulting hydrocarbons of the gasoline fraction are generally linear, leading to a low detonation resistance the resulting gasoline.
Receiving
The oil field contains large accumulations of associated petroleum gas, which collects above the oil in the earth's crust and partially dissolves in it under the pressure of the overlying rocks. Associated petroleum gas, like oil, is a valuable natural source of hydrocarbons. Associated petroleum gas is much poorer than oil in composition. Associated petroleum gas is richer in composition than natural gas in various hydrocarbons. Dividing them into fractions, you get:
- Gas gasoline(pentane and hexane);
- Propane - butane mixture(propane and butane);
- Dry gas(methane and ethane).
Application
Gasoline is used as a fuel for internal combustion engines and also as an additive to motor fuel to facilitate engine starting in winter conditions. Propane-butane mixture is used as household fuel and for filling lighters. Dry gas is widely used as a fuel. Petroleum gas is used as a raw material for chemical production. Hydrogen, acetylene, unsaturated and aromatic hydrocarbons and their derivatives are obtained from alkanes entering the composition of associated petroleum gas. Gaseous hydrocarbons can form independent accumulations - natural gas fields.
Natural gas
Natural gas - a mixture of gaseous saturated hydrocarbons with a low molecular weight. The main component of gas is methane, the share of which, depending on the field, ranges from 75 to 99% by volume. Natural gas also includes ethane, propane, butane, isobutane, nitrogen and carbon dioxide.
Receiving
Natural gas deposits are located in porous rocks formed as a result of tectonic shifts. The layers covering these rocks do not allow gas to pass through. The composition of natural gas differs significantly from one field to another. Therefore, before use, natural gas must be treated to remove unnecessary components, such as sulphurous acid salt, water, etc. Processing is usually carried out at the mining site. At the same time, the removal of sulfur compounds is especially difficult, since toxic sulfur dioxide (SO 2) is released during their combustion.
Application
Natural gas is used as a fuel and as a raw material for the production of various organic and inorganic substances. Hydrogen, acetylene and methyl alcohol, formaldehyde and formic acid are obtained from methane. Natural gas is used as a fuel in power plants, in boiler systems for water heating of residential buildings and industrial buildings, in blast-furnace and open-hearth production. The value of natural gas as a fuel also lies in the fact that it is an environmentally friendly mineral fuel. When burned, much less harmful substances are formed compared to other types of fuel. Therefore, natural gas is one of the main sources of energy in human activity.
In the chemical industry, natural gas is used as a raw material for the production of various organic substances, for example, plastics, rubber, alcohol, organic acids. It was the use of natural gas that helped synthesize many chemicals that do not exist in nature, such as polyethylene.
Coal
Coal - sedimentary rock, which is a product of deep decomposition of plant remains (tree ferns, horsetails and lymphoids, as well as the first gymnosperms). Bituminous coal is composed of organic and inorganic substances such as water, ammonia, hydrogen sulfide and carbon - coal.
Coking - method of processing coal, calcining without air access. At a temperature of about 1000 ° C, as a result of coking, the following are formed:
Short description
Oil is an oily flammable liquid with a specific
odor, usually brown with a greenish or other tinge,
sometimes almost black, very rarely colorless.
Natural and associated petroleum gases.
Natural gas is a mixture of gases, the main component of which is methane, the rest is the share of ethane, propane, butane, and a small amount of impurities - nitrogen, carbon monoxide (IV), hydrogen sulfide and water vapor. 90% of it is consumed as fuel, the remaining 10% is used as a raw material for the chemical industry: the production of hydrogen, ethylene, acetylene, soot, various plastics, medicines, etc.
Associated petroleum gas is also natural gas, but it occurs together with oil - it is above the oil or dissolved in it under pressure. Associated gas contains 30-50% methane, the rest is its homologues: ethane, propane, butane and other hydrocarbons. In addition, it contains the same impurities as in natural gas.
Three fractions of associated gas:
Gas gasoline; it is added to gasoline to improve engine starting;
Propane-butane mixture; used as household fuel;
Dry gas; are used to obtain acithelene, hydrogen, ethylene and other substances, from which rubbers, plastics, alcohols, organic acids, etc. are produced.
Oil.
Oil is a yellow or light brown to black oily liquid with a characteristic odor. It is lighter than water and practically insoluble in it. Oil is a mixture of about 150 hydrocarbons mixed with other substances, so it does not have a specific boiling point.
90% of the oil produced is used as feedstock for the production of various types of fuels and lubricants. At the same time, oil is a valuable raw material for the chemical industry.
I call crude oil extracted from the bowels of the earth. Crude oil is not used, it is processed. Crude oil is purified from gases, water and mechanical impurities, and then subjected to fractional distillation.
Distillation is the process of separating mixtures into individual components, or fractions, based on the difference in their boiling points.
When distilling oil, several fractions of oil products are isolated:
The gas fraction (tboil \u003d 40 ° C) contains normal and branched alkanes CH4 - C4H10;
Gasoline fraction (tboil \u003d 40 - 200 ° C) contains hydrocarbons C 5 H 12 - C 11 H 24; during repeated distillation, light oil products are released from the mixture, boiling in lower temperature ranges: petroleum ether, aviation and motor gasoline;
The naphtha fraction (heavy gasoline, bp \u003d 150 - 250 ° C), contains hydrocarbons of the composition C 8 H 18 - C 14 H 30, is used as fuel for tractors, diesel locomotives, trucks;
The kerosene fraction (tboil \u003d 180 - 300 ° C) includes hydrocarbons of the composition C 12 H 26 - C 18 H 38; it is used as fuel for jet aircraft, missiles;
Gas oil (bp \u003d 270 - 350 ° C) is used as diesel fuel and is cracked on a large scale.
After distillation of fractions, a dark viscous liquid remains - fuel oil. Diesel oils, petroleum jelly, paraffin are isolated from fuel oil. The residue from the distillation of fuel oil is tar, it is used in the production of materials for road construction.
Secondary oil refining is based on chemical processes:
Cracking is the splitting of large hydrocarbon molecules into smaller ones. Distinguish between thermal and catalytic cracking, which is more common today.
Reforming (aromatization) is the transformation of alkanes and cycloalkanes into aromatic compounds. This process is carried out by heating gasoline at elevated pressure in the presence of a catalyst. Reforming is used to obtain aromatic hydrocarbons from gasoline fractions.
Pyrolysis of petroleum products is carried out by heating petroleum products to a temperature of 650 - 800 ° C, the main reaction products are unsaturated gaseous and aromatic hydrocarbons.
Oil is a raw material for the production of not only fuel, but also many organic substances.
Coal.
Bituminous coal is also a source of energy and a valuable chemical raw material. The composition of coal contains mainly organic substances, as well as water, minerals, which form ash when burned.
One of the types of coal processing is coking - a process of heating coal to a temperature of 1000 ° C without air access. Coal coking is carried out in coke ovens. Coke is made up of almost pure carbon. It is used as a reducing agent in the blast furnace production of cast iron in metallurgical plants.
Volatiles during condensation coal tar (contains many different organic substances, most of them are aromatic), ammonia water (contains ammonia, ammonium salts) and coke oven gas (contains ammonia, benzene, hydrogen, methane, carbon monoxide (II), ethylene , nitrogen and other substances).