Coal and Petroleum PDF

Coal and Petroleum "n our everyday lite, we use a large number of materials for our basic needs. Some of these materials are found in nature whereas others are man-made. Air, water, soil, sunlight, coal,...

Coal and Petroleum "n our everyday lite, we use a large number of materials for our basic needs. Some of these materials are found in nature whereas others are man-made. Air, water, soil, sunlight, coal, petroleum, natural gas and minerals are obtained from nature, so they are called natural resources.On the other hand, plastics, synthetic fibres, paints, drugS, explosives, etc., are all man-made materials. Inexhaustible and Exhaustible Natural Resources Anything in the environment 'which can be used' is called a 'resource'. All the natural resources can be classified into two main groups : () Inexhaustible natural resources, and (i) Exhaustible natural resources. The term 'inexhaustible' means something 'which cannot be used up completely'. Those natural resources which are present in unlimited quantity in nature and are not likely to be exhausted by human activities are called inexhaustible natural resources. The examples of inexhaustible natural resources are: Sunlight, Air and Water. There is a never ending supply of inexhaustible resources in nature. The inexhaustible resources can be used again and again. They last forever. The term 'exhaustible' means 'something which can be used up completely' (so that nothing is left behind). Those resources which are present in a limited quantity in nature and can be exhausted by human activities, are called exhaustible natural resources. The examples of exhaustible natural resources are :Coal, Petroleum, Natural gas, Minerals, Forests and Wildlife, etc. The exhaustible natural resources do not last forever. In this Chapter we will study some exhaustible sources of energy like coal, petroleum and natural gas. Coal, petroleum and natural gas are also called non-renewable sources of energy. This is because when allthe coal, petroleum and natural gas present under the earth will get used up (or exhausted), no more should know the supply of these fuels will be available in the near future. Before we go further, we meaning of the term 'fossil'. Fossils are the remains of the pre-historicplants or animals, buried under the earth millions of years ago. 81 gla 82 AWARI NESS SO ENO FOR FIGHIHIASS FOSSIL FUELS The natural fucls formed from the remains of living organisms buried under the earth long, \ong ago, are called fossilfuels Coal, petroleum and natural gas are fossil fuels. Coal,petroleum and atn gas are called fossil fuels because they were formed by the decomposition of the remains of pre-hinate plants and animals (fossils) buried under the earth long, long ago. Fossil fuels are exhaustible storic resoures because one all the fossil fuels are used up, they will be gone forever. How Fossil Fuels were Formed Fossil fuels were formed from the dead remains of living organisms (plants and animals) buris under the carth millions of years ago. This happened as follows :The plants and animals which died millions of years ago, were gradually buried deep in the earth and got covered with sediments like m and sand, away fronm the reach of air. In the absence of air, the chemical effects of heat, pressure a bacteria, converted the buried remains of plants and animals into fossil fuels like coal, petroleum and natural gas. Please note that the buried remains of large land plants were converted into coal whereas the of tiny marine plants and animals were converted into petroleum and natural gas. COAL Coal is a hard, black combustible mineral that consists mainly of carbon (see Figure 1).Coal is found in deep coal mines under the surface of the earth. In India, coal is found mainly in Bihar, West Bengal, Orissa and Madhva Pradesh. Coal is found in abundance in our country and it is the most important source of energy in our country. How Coal was Formed Coal was formed by the decomposition of large land plants and trees buried under the earth about 300 million years ago. This happened as follows: About 300 million years ago, the earth had dense forests in low lying wet land areas. Due to natural processes like earthquakes, volcanoes Figure 1. Coal. and floods, etc., these forests were buried under the surface of earth. As more soil deposited over them, they were compressed. The temperature also rose as they sank dee deeper. Due to high pressure and high temperature inside the earth, and in the absence of air, the buried forest plants and trees was slowly converted into coal. The slow process by which the deadp buried deep under the earth have become coal is called carbonisation. Since coal was formed from te remains of plants, therefore, coal is called a fossil fuel. Coal is a Source of Energy Coal is mainly carbon. When heated in air, coal burns and produces mainly carbon dioxide gas. Alot of heat energy is also produced during the burning of coal. This can be written as : Carbon Oxygen Carbon dioxide + Heat (Coal) (From air) Coal is important because it can be used as asource of heat energy as such (just by burning it), or it can be converted into other forms of energy such as coal gas, coke or electricity. The real source of energy of coal is the solar energy (or sun's energy). This is because the plants and trees which decomposed to form coal grew on the earth by absorbing sunlight energy during the process of photosynthesis. Uses of Coal (i) Coal is used as a fuel in homes and industry. (i)Coal is used as a fuel at Thermal Power Plants for generating electricity. (ii)Coal is used to make coal gas which is an important industrial fuel.  COAL AND PETROLEUM 83 coke. (ip) Coal is used to make () Earlier, coal was used as afuel to make 'steam' to run steam engines of trains. (ri) Coal was also used as a source of organic chemicals. Products of Coal When coal is heated strongly in closed retorts in the absence of air, a number of useful products are obtained. The various useful products obtained by processing thecoal by heating in the absence of air are: () Coal gas, (ii) Coal tar, and (ii) Coke. Coal gas,coal tar and coke are called products of coal. Please note that these products are obtained Lo coaiis heated in the absence of air. This is because ifcoal is heated in the presence of air, then coal rns to produce mainly carbon dioxide gas and noother useful products are obtained. The strong heating teoal in the absence of air is called destructive distillation of coal. We will now describe the various products of coal in somewhat detail. Coal Gas of air Coal gas is a gaseous fuel which is obtained by the strong heating of coal in the absence hydrogen, with during the processing of coal to get coke. Coal gas is mainly a mixture of methane and heat, due to which coal gas some carbon monoxide. All the gases present in coal gas can burn to produce industries (which are situated is an excellent fuel (having high calorificvalue). Coal gas is used as a fuel in light. So, in the near the coal processing plants). When coal gas burns, it also produces a good amount ofgas was used for past, coal gas has also been used for lighting purposes (or illumination purposes). Coal street lighting in New York street lighting for the first time in London in the year 1810. It was used for than light. around 1820. These days, however, Coal gas is used as a source of heat rather Coal Tar Coal tar is a thick, black liquid having an unpleasant smell which is is obtained by heating coal in the absence of air (see Figure 2). Coal tar 200 carbon not a single compound. Coal tar is a mixture of about (or compounds (or organic compounds). The useful carbon compounds benzene, toluene, organic compounds) present in coal tar include naphthalene, anthracene, phernol and aniline. Thus, the naphthalene balls obtained used to repel moths and other insects (in stored clothes, etc.) are from coal tar. The various compounds present in coal tar are separated by products) the process of fractional distillation. The compounds (or obtained from coal tar are used as starting materials for manufacturing a For large number of substances used in everyday life and industry. Figure 2. Coal tar. example, the products of coal tar are used to make synthetic fibres, drugs (medicines), plastics, synthetic dyes, perfumes, paints, varnishes, pesticides, photographic materials, roofing materials and explosives, etc. Coal tar has been traditionally used for metalling the roads. These days, however, bitumen (a petroleum product) is being used increasingly for metalling the road surfaces (in place of coal tar). Coke Coke is a tough and porous black solid substance (see Figure 3). Coke is prepared by heating coal in the absence of air. When coal is heated in the absernce of air, then coal gas and coal tar are eliminated, and coke is left behind as a black residue. Thus, coal minus volatile constituents Figure 3. Coke. is coke. Coke is an almost pure form of carbon. It is 98 per cent carbon.  Coke is mainlyof used manufacture steel. Cokeis also used as afucl. Coke is a better fuel than coal because it produCes more heat on burning than an equal amount of coal. Moreover, coke burns without producing any smoke smoke on burning. whereas coal produces a lot of PETROLEUM Petroleum is a dark coloured, thick crude oil found deep below the ground in certain areas. lt has an unpleasant odour. The name 'petroleum' means 'rock oil (petra = rock ; oleum = oil). It is called of earth trapped in rocks. petroleum because it is found under the crust Petroleum is a complex Petroleum is not asingle chemical compound. hydrocarbons (Hydrocarbons are mixture of compounds known as two elements : carbon and compounds which are made up of only Petroleum is a natural hvdrogen). Petroleum is insoluble in water. are dug in certain areas of resource obtained from deep oil wells which fossil fuel. Please note that the earth. Just like coal, petroleum is also a oil'. or 'mineral petroleum is also called 'crude oil' Formed How Petroleum was the remains of Petroleunm (oil) was formed by the decomposition of years millions of ago, It is tiny plants and animals buried under the sea animals which believed that millions of years ago, the tiny plants and bottom of sea and sank to the lived in the sea, died. Their dead bodies pressure, heat. were soon covered with mud and sand. Due to high remains of tiny dead action of bacteria, and in the absence of air, the into petroleum. The plants and animals were slowly converted Figure 4. Petroleum (Crud petroleum thus formed got trapped between two layers of impervious deposit. rocks (non-porous rocks), forming an oil Petroleum Occurrence and Extraction of Petroleunm occurs deep under the surtace of earth between two layers of impervious rocks (see usually found Figure 5). Petroleum is lighter than water, so it floats over water. Petroleum oil deposits areplaces in all the of earth. mixed with water, salt and earth particles (sand, etc.). Petroleum does not occur earth. It is found in only certain areas of the Natural gas occurs above the petroleum oil Drilingrig trapped under the rocks (see Figure 5). Natural gas Petroleum is extracted by drilling holes (called oil wells) in the earth's crust, where the -Earth's crust presence of oil has been predicted by survey. Shale The oil wells are drilled by using 'drilling rigs(A drilling rig is a large structure with equipment Impervious rock for drilling an oil well). When an oil well is Petroleum drilled through the rocks, natural gas comes out Water first with a great pressure and for a time, the Impervious rock crude petroleum oil comes out by itself due to gas pressure. After the gas pressure has Figure 5., Petroleum and natural gas deposits under the surface of earth. subsided, petroleum is pumped out of the oil well. Some wells dug into the earth yield both petroleum and natural gas but some wells yield only natural gas but no oil. Early drilling of oil wells før getting petroleum was done only on land. Later on, oil wells were also drilled under the sea-bed by using new technigques. Thus,some of the oil wells are now drilled under the sea for the extraction of petroleum.  COAL AND PETROLEUM 85 The world's first oil well was drilled in Pennsylvania(USA) in 1859. Eight years later in 1867, oil was struck at Makumin Assam. In India, petroleum (oil) is found in Assam, Gujarat, Mumbai High (off-shore Mumbai area).and near the basins of Godavari and Krishna rivers. The off-shore oil bearing area called Highislocated in high seas at a distance of about 150 kilometres west of Mumbai city. The oil deposits of Mumbai Highare buried at adepth of about 1000 metres below the sea-bed. Aspecial platform of steel has beenerected in the Mumbai High sea to pump out petroleum from under the sea-bed. Refining of Petroieum The crude petroleum oil is a complex mixture of solid, liquid and gaseous hvdrocarbons. It is not very useful to us as such. So, betore petroleum can be used for specific purposes, it has to be ofined(or purified). The process of separating crude petroleum oil into more useful fractions is called refining. The refining of netroleum (or separation of petroleum) into different fractions is hased on the fact that the different fractions of petroleum have different boiling point ranges. The refining of petroleum is carried out in an oil refinery (see Figure 6). The crude petroleum oil extracted from oil wells is taken to the oil refinery' through pipes. In the oil refinery,crude petroleum oil is refined (or separated) into aifferent useful fractions. The separation of petroleum into different fractions is done by the process of 'fractional distillation'. Fractional distillation is a process in which fractions of petroleumn having different boiling point ranges are collected separately. The various useful fractions obtained by the refining of petroleum are : Petroleum gas, Petrol, Kerosene, Diesel, Lubricating oil, Paraffin wax and Bitumen. Figure 6. An oil refinery. The Various Fractions of Petroleum and Their Uses The refining of petroleum gives the fractions (or products) such as petroleum gas, petrol, kerosene, diesel, lubricating oil, paraffin wax and bitumen. The importarnt uses of the various fractions of petroleum are given below. (PETROLEUM GAS.Petroleum gas is used as a fuel in homes and industry. Petroleum gas is used as a fuel as such or in the form of Liquefied Petroleum Gas (LPG). (i2 PETROL.Petrol is used as a fuel in light motor vehicles (such as cars, motorcycles, and scooters, etc.). Petrol is also used as a solvent for drycleaning. (iji) KEROSENE. Kerosene is used as a fuel in wick stoves and pressure stoves to cook food. Kerosene is also used in lanterns for lighting purposes (see Figure 7). A special grade of kerosene oil is used as aviation fuel in jet aeroplanes. (io) DIESEL. Diesel is used as a fuel in heavy motor vehicles (such as buses, trucks, tractors, and diesel train engines). Diesel is also used to run pump sets for irrigation in agriculture and in electric generators (to produce electricity on a small scale). (LUBRICATING OIL. Lubricating oil is used for lubrication in machines and engines (like car engines). Figure 7.Kerosene is used as a fuel in lanterns.  4114RENESS S IENEFOR fIGHTH (ASS (r) FARAFIN WAX. P'araffin wax is used for making candles, vaseline, ointments, wax paper, and (ri) BITUMEN. Bitumen is used for road surfacing. It is also used for water-proofing the roofs of buldings Bitumen is used in making black paints. diesel are also fossil Tlease note that tlhe fuels such as petroleum gas, petrol, kerosene, and bevause thev are obtained from a major fossil fuel called petroleum). fuels The most common fuel used in homes is liquefied petroleum gas pressure (or LPG). The petroleum gas which has been liquefied under is called liquefied petroleum gas. The liquefiedhas petroleum gas (or LPG) consists mainlv of butane (C,H,) (which been liquefied by like "Indane applving pressure). Thus, the domestic gas cylindersdomestic cooking contain mainlv butane (see Figure 8). The gas used for petroleum and it is is called liqucficd petroleum gas because it is obiained from When we turn liqucticd by conpression before filling into the gas cylinders. released, due to which on the knob of the gas cylinder, the pressure is goes into the the highlv volatile LPG is converted into gas. This gasapplied to the burner of LPG stove. When a lighted matchstick is heat. This burner, the gas burns with a blue flame producing a lot of heat is used for cooking food. Liquefied petroleum gas (LPG) is agood Figure &. These gas cylinders contain fuel because of its following advantages : LPG. (i) LPG burms easily. (i) LPGhas a high calorificvalue. Due to this, a given amount of LPG produces a lot of heat (iü) LPG burns with a smokeless flame and/hence does not cause air pollution. (iv) LPGdoes not produce any poisonou gases on burning. (o) LPG does not leave behind any solid residue on burning. We will now discuss natural gas. NATURAL GAS Natural gas consists mainly of methane with small quantities of ethane and propane. In fact, natural gas contains about 95% methane, the remaining being ethane and propane. Natural gas occurs deep under the crust of earth either alone or alongwith ol above the petroleum deposits. Thus, some wells dug into the earth produce only natural gas whereas others produce natural gas as well as petroleum oil. Natural gas formed under the earth by the decomposition of vegetable matter lying under water. This decompositior is carried out by anaerobic bacteria in the absence of air. Just like coal and petroleum, natural gas is also a fossil fuel. India has vast reserves of natural gas. In India, natural gas has been found in Tripura, Rajasthan, Maharashtra, and in Krishna-Godavari delta. When natural gas is compressed by applying pressure, it is calledCompressed Natural Gas (which is written in short form as CNG). In fact, natural gas is stored under high pres_ure as compressed natural gas (or CNG). It becomes easier to store, transport and use natural gas in the form of CNG. Natural gas is called aclean fuel because it burns without producing any smoke and does not cause air pollution. Advantages of Using Natural Gas (or Compressed Natural Gas, CNG) 1. Natural gas (or CNG) is agood fuel because it burns easily and produces alot of heat. Moreover, natural gas burns with a smokeless flame and causes no air pollution. It also does not produge any poisonous gases on burning. Natural gas does not leave behind any solid residue on burning. Natdral gas is, therefore, a clean fuel (as compared to other fossil fuels). 2. Natural gas (or CNG) is acomplete fuel in itself and can be used directly for heating purposes in homes and industry. There is no need to add anything else to it.  COAL AND PETROLEUM 87 2 Agreat advantage of natural gas is that it canforbe supplied ot underground pipes and this eliminates the need additionaltostorage homes and and transport. factories through Such a network a tet of lines for the supplv of natural gas exists in Vadodara (in other places. Gujarat), in some parts of Delhi and a fe Ilses of Natural Gas (or CNG) 1 Natural gas is used as a domestic and industrial fuel. , Natural gas is used as a fuel in Thermal Power Stations for generating electricity. 3. Compressed natural gas (CNG) is being used increasingly as afuel in transport vehicles (like cars, buses, etc.) in place of petrol and diesel. CNG is a good alternative to petrol snddiescl in vehicles because it is a cleaner fuel and does not cause much air pollution. In fact, CNG is being used in many vehicles these days to reduce air pollution in cities. CNG which is used in vehicles is filled in cylinders. These cylinders can be refilled at CNG Filling Stations (see Figure 9). 4. Natural gas is used as a source of hydrogen gas needed to manufacture fertilisers. When natural gas is heated strongly, the methane present in it decomposes to form carbon and hvdrogen. This hydrogen is then used to manufacture fertilisers. Figure 9. CNG being filled in a car at a Filling Station. 5. Natural gas is used as a starting material for the manufacture of a number of chemicals (which are called petrochemicals). PETROCHEMICALS Many useful chemicals (or substances) are obtained from petroleum and natural gas. Those chemicals which are obtained from petroleum and natural gas are called petrochemicals, Some examples of petrochemicals are : methyl alcohol,ethyl alcohol, formaldehyde, acetone, acetic acid,ethylene, benzene, toluene, vinyl chloride and hydrogen. Petrochemicals are very important because they are used to manufacture a wide range of useful materials such as : Detergents, Synthetic fibres (like Polyester, Nylon, Acrylic, etc.), Plastics (such as Polytherne, Polyvinyl chloride, Bakelite, etc.), Synthetic rubber, Drugs, Dyes, Perfumes, Fertilisers, Insecticides and Explosives, etc. Hydrogen gas is obtained as a petrochemical from natural gas. Hydrogen gas obtained from natural gas is used in the manufacture of fertilisers (such as ammonium nitrate and urea). Thus,petroleum is not only a source of fuels but also provides raw materials (in the form of petrochemicals) to manufacture a large number of useful substances. Due to its great commercial importance, petroleum is also called "black gold". Energy Resources of Earth are Limited Most of the energy that we use today comes mainly from the three exhaustible resources of the earth: coal, petroleum and natural gas The amount of coal, petroleum and natural gas present in the earth is limited. The known reserves of coal, petroleum and natural gas will last only for about 100 years. Once the present stock of coal, petroleum and natural gas present in the earth gets exhausted, no new supplies of these fossil fuels will be available tous in the near future (because it takes millions of years to convert the dead organisms into fossil fuels in nature). So, fossil fuels should be used with care and caution, and not wasted at all so that the existing reserves of fossil fuels can be used over as long a period as possible. Moreover, the burning of fossil fuels is a major source of air pollution. The use of fossil fuels is also Iinked to global warming (because they produce a lot of greenhouse gas 'carbon dioxide' on burning). So, the use of lesser fossil fuels willlead to cleaner environment and smaller risk of global warming. From the above discussion we conclude that we should use fossil fuels only when absolutely necessary because :  88 AWARENESS SCIENCE FOR EIGHTH CLASS () it will ensure the availability of fossil fuels for a longer period of time. () it will reduce air pollution and lead to a cleaner environment. () it will reduce the risk of global warming. Please note that the fossil fuels such as coal, petroleum and natural gas cannot be prepared in the fuels i laboratory from dead organisms (dead plants and animals). This is because the formation of fossil a verv. verv slow process and the conditions for their formation cannot be created in the laborator. How to Save Petrol and Diesel Petrol and diesel are the two main fuels which are used for driving vehicles. We should make etrems Research effort to avoid the wastage of these precious fuels. In India, the Petroleum Conservation Association (PCRA) advises people on how to save petrol (or diesel) while driving vehicles. The various as follows : tips for minimising the wastage of petrol and diesel while driving vehicles are (i) Drive the vehicle at a constant and moderate speed as far as pOssible. (ii) Switch off the vehicle sengine at traffic lights or at a place where a person has to wait. fuel. (i1) Ensure correct air pressure in thetyres of the vehicle. Low tyre pressure consumes more (iv) Ensure regular maintenance of the vehicle (including engine tuning). We are now in a position to answer the following questions :