1.
Coal
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Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon, along with quantities of other elements, chiefly hydrogen, sulfur, oxygen. A fossil fuel, coal forms when plant matter is converted into peat, which in turn is converted into lignite, then sub-bituminous coal, after that bituminous coal. This involves biological and geological processes that take place over time, throughout history, coal has been used as an energy resource, primarily burned for the production of electricity and heat, and is also used for industrial purposes, such as refining metals. Coal is the largest source of energy for the generation of electricity worldwide, the extraction of coal, its use in energy production and its byproducts are all associated with environmental and health effects including climate change. Coal is extracted from the ground by coal mining, since 1983, the worlds top coal producer has been China. In 2015 China produced 3,747 million tonnes of coal –47. 7% of 7,861 million tonnes world coal production, in 2015 other large producers were United States, India, European Union and Australia. The word originally took the col in Old English, from Proto-Germanic *kula. In Old Turkic languages, kül is ash, cinders, öčür is quench, the compound charcoal in Turkic is öčür kül, literally quenched ashes, cinders, coals with elided anlaut ö- and inflection affixes -ülmüş. At various times in the geologic past, the Earth had dense forests in low-lying wetland areas, due to natural processes such as flooding, these forests were buried underneath soil. As more and more soil deposited over them, they were compressed, the temperature also rose as they sank deeper and deeper. As the process continued the plant matter was protected from biodegradation and oxidation and this trapped the carbon in immense peat bogs that were eventually covered and deeply buried by sediments. Under high pressure and high temperature, dead vegetation was slowly converted to coal, as coal contains mainly carbon, the conversion of dead vegetation into coal is called carbonization. The wide, shallow seas of the Carboniferous Period provided ideal conditions for coal formation, the exception is the coal gap in the Permian–Triassic extinction event, where coal is rare. Coal is known from Precambrian strata, which predate land plants — this coal is presumed to have originated from residues of algae, in its dehydrated form, peat is a highly effective absorbent for fuel and oil spills on land and water. It is also used as a conditioner for soil to make it able to retain. Lignite, or brown coal, is the lowest rank of coal, jet, a compact form of lignite, is sometimes polished and has been used as an ornamental stone since the Upper Palaeolithic
2.
Coal preparation plant
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The more of this waste material that can be removed from coal, the lower its total ash content, the greater its market value and the lower its transportation costs. The coal delivered from the mine that reports to the preparation plant is called run-of-mine, or ROM. This is the raw material for the CPP, and consists of coal, rocks, middlings, minerals, contamination is usually introduced by the mining process and may include machine parts, used consumables and parts of ground engaging tools. ROM coal can have a large variability of moisture and maximum particle size, Coal needs to be stored at various stages of the preparation process, and conveyed around the CPP facilities. Coal handling is part of the field of bulk material handling. Stockpiles provide surge capacity to various parts of the CPP, ROM coal is delivered with large variations in production rate of tonnes per hour. A ROM stockpile is used to allow the washplant to be fed coal at lower, a simple stockpile is formed by machinery dumping coal into a pile, either from dump trucks, pushed into heaps with bulldozers or from conveyor booms. More controlled stockpiles are formed using stackers to form piles along the length of a conveyor, taller and wider stockpiles reduce the land area required to store a set tonnage of coal. Larger coal stockpiles have a rate of heat loss, leading to a higher risk of spontaneous combustion. Travelling, luffing boom stackers that straddle a feed conveyor are commonly used to create coal stockpiles, tunnel conveyors can be fed by a continuous slot hopper or bunker beneath the stockpile to reclaim material. Front-end loaders and bulldozers can be used to push the coal into feeders, sometimes front-end loaders are the only means of reclaiming coal from the stockpile. This has a low up-front capital cost, but much higher operating costs, high-capacity stockpiles are commonly reclaimed using bucket-wheel reclaimers. These can achieve high rates Sampling of coal is an important part of the process control in the CPP. A grab sample is a sample of the coal at a point in the process stream. A routine sample is taken at a set frequency, either over a period of time or per shipment, Coal sampling consists of several types of sampling devices. A cross cut sampler mimics the stop belt sampling method specified by a standard published by the American Society for Testing. A cross cut sampler mounts directly on top of the conveyor belt, there are several points in the wash plant that many coal operations choose to sample. The raw coal, before it enters the plant, the refuse, to see what the plant missed
3.
Peat
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Peat, also called turf, is an accumulation of partially decayed vegetation or organic matter that is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem is the most efficient carbon sink on the planet because peatland plants capture the CO2 which is released from the peat. Sphagnum moss is one of the most common components in peat, soils that contain mostly peat are known as histosols. Peat forms in wetland conditions, where flooding obstructs flows of oxygen from the atmosphere, Peatlands, particularly bogs, are the most important source of peat. That said, other less common types, including fens, pocosins. Landscapes covered in peat are home to specific kinds of plants including Sphagnum moss, ericaceous shrubs, because organic matter accumulates over thousands of years, peat deposits also provide records of past vegetation and climates stored in plant remains like pollen. This allows humans to reconstruct past environments and study changes in land use. Peat is harvested as an important source of fuel in certain parts of the world, by volume, there are about 4 trillion cubic metres of peat in the world, covering a total of around 2% of the global land area, containing about 8 billion terajoules of energy. Over time, the formation of peat is often the first step in the formation of other fossil fuels such as coal. This is also the commonly used in the peat industry. At 106 g CO2/MJ, the carbon dioxide emission intensity of peat is higher than that of coal and natural gas, lastly, peat fires have been responsible for large public health disasters including the 1997 Southeast Asian haze. Peat forms when plant material does not fully decay in acidic and anaerobic conditions and it is composed mainly of wetland vegetation, principally bog plants including mosses, sedges, and shrubs. As it accumulates, the peat holds water and this slowly creates wetter conditions that allow the area of wetland to expand. Peatland features can include ponds, ridges, and raised bogs, most modern peat bogs formed 12,000 years ago in high latitudes after the glaciers retreated at the end of the last ice age. Peat usually accumulates slowly at the rate of about a millimetre per year, using Carbon-dating, scientists found that Peat in peatlands started forming 360 million years ago based on it currently containing 550 Gt of carbon. Peat material is either fibric, hemic, or sapric, fibric peats are the least decomposed and consist of intact fiber. Hemic peats are partially decomposed and sapric are the most decomposed, Phragmites peat is one composed of reed grass, Phragmites australis, and other grasses. It is denser than other types of peat
4.
Lignite
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Lignite, often referred to as brown coal, is a soft brown combustible sedimentary rock formed from naturally compressed peat. It is considered the lowest rank of coal due to its low heat content. It has a carbon content around 60–70 percent and it is mined all around the world and is used almost exclusively as a fuel for steam-electric power generation, but is also mined for its germanium content in China. The energy content of lignite ranges from 10 to 20 MJ/kg on a moist, the energy content of lignite consumed in the United States averages 15 MJ/kg, on the as-received basis. The energy content of lignite consumed in Victoria, Australia, averages 8.4 MJ/kg, lignite has a high content of volatile matter which makes it easier to convert into gas and liquid petroleum products than higher-ranking coals. Unfortunately, its moisture content and susceptibility to spontaneous combustion can cause problems in transportation. However, removing the moisture increases the cost of the final lignite fuel, because of its low energy density and typically high moisture content, brown coal is inefficient to transport and is not traded extensively on the world market compared with higher coal grades. It is often burned in power stations near the mines, such as in Australias Latrobe Valley, the operation of traditional brown-coal plants, particularly in combination with strip mining, can be politically contentious due to environmental concerns. An environmentally beneficial use of lignite can be found in its use in cultivation and distribution of biological control microbes that suppress plant disease causing microbes, lignite begins as an accumulation of partially decayed plant material, or peat. Burial by other sediments results in increasing temperature, depending on the geothermal gradient and tectonic setting. This causes compaction of the material and loss of some of the water and this process, called coalification, concentrates the carbon content, and thus the heat content, of the material. Deeper burial and the passage of time result in expulsion of moisture and volatile matter, eventually transforming the material into higher rank coals such as bituminous. Lignite deposits are younger than higher-ranked coals, with the majority of them having formed during the Tertiary period. The Latrobe Valley in the state of Victoria, Australia, contains estimated reserves of some 65 billion tonnes of brown coal, the deposit is equivalent to 25 percent of known world reserves. The coal seams are up to 100 metres thick, with coal seams often giving virtually continuous brown coal thickness of up to 230 metres. Seams are covered by little overburden. Lignite can be separated into two types, the first is xyloid lignite or fossil wood and the second form is the compact lignite or perfect lignite. Although xyloid lignite may sometimes have the tenacity and the appearance of ordinary wood and it is reducible to a fine powder by trituration, and if submitted to the action of a weak solution of potash, it yields a considerable quantity of humic acid
5.
Anthracite
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Anthracite is a hard, compact variety of coal that has a submetallic luster. It has the highest carbon content, the fewest impurities, Anthracite is the most metamorphosed type of coal, in which the carbon content is between 92. 1% and 98%. The term is applied to varieties of coal which do not give off tarry or other hydrocarbon vapours when heated below their point of ignition. Anthracite ignites with difficulty and burns with a short, blue, Anthracite is categorized into standard grade, which is used mainly in power generation, and high grade and ultra high grade, the principal uses of which are in the metallurgy sector. Anthracite accounts for about 1% of global reserves, and is mined in only a few countries around the world. China accounts for the majority of production, other producers are Russia, Ukraine, North Korea, South Africa, Vietnam, the UK, Australia, Canada. Total production in 2010 was 670 million tons, Anthracite derives from the Greek anthrakítēs, literally coal-like. Other terms which refer to anthracite are black coal, hard coal, stone coal, dark coal, coffee coal, blind coal, Kilkenny coal, crow coal or craw coal, markets to distinguish it from its competitors. Culm has different meanings in British and American English, england, culm is the imperfect anthracite of north Devon and Cornwall, which was used as a pigment. The term is used to refer to the rock strata whose deposits are found in both Britain and in the Rhenish hill countries. Lastly, it may refer to coal exported from Britain during the 19th century, america, culm refers to the waste or slack from anthracite mining, mostly dust and small pieces not suitable for use in home furnaces. Anthracite is similar in appearance to the jet and is sometimes used as a jet imitation. Anthracite differs from ordinary bituminous coal by its hardness, its higher relative density of 1. 3–1.4, and luster. It contains a percentage of fixed carbon and a low percentage of volatile matter. It is also free from included soft or fibrous notches and does not soil the fingers when rubbed, anthracitization is the transformation of bituminous coal into anthracite. The moisture content of fresh-mined anthracite generally is less than 15 percent, the heat content of anthracite ranges from 22 to 28 million Btu per short ton on a moist, mineral-matter-free basis. The heat content of coal consumed in the United States averages 25 million Btu/ton, on the as-received basis. Since the 1980s, anthracite refuse or mine waste has been used for power generation in a form of recycling
6.
Graphite
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Graphite, archaically referred to as plumbago, is a crystalline form of carbon, a semimetal, a native element mineral, and one of the allotropes of carbon. Graphite is the most stable form of carbon under standard conditions, therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds. Highly ordered pyrolytic graphite or more correctly highly oriented pyrolytic graphite refers to graphite with a spread between the graphite sheets of less than 1°. The name graphite fiber is sometimes used to refer to carbon fibers or carbon fiber-reinforced polymer. Graphite occurs in rocks as a result of the reduction of sedimentary carbon compounds during metamorphism. It also occurs in rocks and in meteorites. Minerals associated with graphite include quartz, calcite, micas and tourmaline, in meteorites it occurs with troilite and silicate minerals. Small graphitic crystals in meteoritic iron are called cliftonite, Graphite is not mined in the United States, but U. S. production of synthetic graphite in 2010 was 134 kt valued at $1.07 billion. Graphite has a layered, planar structure, the individual layers are called graphene. In each layer, the atoms are arranged in a honeycomb lattice with separation of 0.142 nm. Atoms in the plane are bonded covalently, with three of the four potential bonding sites satisfied. The fourth electron is free to migrate in the plane, making graphite electrically conductive, however, it does not conduct in a direction at right angles to the plane. Bonding between layers is via weak van der Waals bonds, which allows layers of graphite to be easily separated, the two known forms of graphite, alpha and beta, have very similar physical properties, except for that the graphene layers stack slightly differently. The alpha graphite may be flat or buckled. The alpha form can be converted to the form through mechanical treatment. The acoustic and thermal properties of graphite are highly anisotropic, since phonons propagate quickly along the tightly-bound planes, graphites high thermal stability and electrical and thermal conductivity facilitate its widespread use as electrodes and refractories in high temperature material processing applications. However, in oxygen containing atmospheres graphite readily oxidizes to form CO2 at temperatures of 700 °C, Graphite is an electric conductor, consequently, useful in such applications as arc lamp electrodes. It can conduct electricity due to the vast electron delocalization within the carbon layers and these valence electrons are free to move, so are able to conduct electricity
7.
Coke (fuel)
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Coke is a fuel with few impurities and a high carbon content, usually made from coal. It is the carbonaceous material derived from destructive distillation of low-ash. Cokes made from coal are grey, hard, and porous, while coke can be formed naturally, the commonly used form is man-made. The form known as coke, or pet coke, is derived from oil refinery coker units or other cracking processes. Coke is used in preparation of producer gas which is a mixture of carbon monoxide, producer gas is produced by passing air over red-hot coke. Coke is also used to water gas. Historical sources dating to the 4th century describe the production of coke in ancient China, the Chinese first used coke for heating and cooking no later than the ninth century. By the first decades of the century, Chinese ironworkers in the Yellow River valley began to fuel their furnaces with coke. In 1589 a patent was granted to Thomas Proctor and William Peterson for making iron and steel and melting lead with earth-coal, sea-coal, turf, the patent contains a distinct allusion to the preparation of coal by cooking. In 1590 a patent was granted to the Dean of York to purify pit-coal, in 1620 a patent was granted to a company composed of William St. John, Robert Follensbee and other knights, mentioning the use of coke in smelting ores and manufacturing metals. In 1627 a patent was granted to Sir John Hacket and Octavius de Strada for a method of rendering sea-coal and pit-coal as useful as charcoal for burning in houses, without offense by smell or smoke. In 1603 Hugh Plat suggested that coal might be charred in an analogous to the way charcoal is produced from wood. In 1709 Abraham Darby I established a coke-fired blast furnace to produce cast iron, cokes superior crushing strength allowed blast furnaces to become taller and larger. The ensuing availability of iron was one of the factors leading to the Industrial Revolution. Before this time, iron-making used large quantities of charcoal, produced by burning wood, in the late 18th century, brick beehive ovens were developed, which allowed more control over the burning process. In 1768 John Wilkinson built a more practical oven for converting coal into coke, with greater skill in the firing, covering and quenching of the heaps, yields were increased from about 33 per cent to 65 per cent by the middle of the 19th century. The Scottish iron industry expanded rapidly in the second quarter of the 19th century. In 1802 a battery of beehives was set up near Sheffield, by 1870, there were 14,000 beehive ovens in operation on the West Durham coalfields, capable of producing 4.2 million tons of coke
8.
Coal mining
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Coal mining is the process of extracting coal from the ground. Coal is valued for its content, and, since the 1880s, has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore, in the United Kingdom and South Africa a coal mine and its structures are a colliery, a coal mine a pit, the above-ground structures the pit head. In Australia, colliery generally refers to a coal mine. In the United States colliery has been used to describe a coal mine operation, Coal mining has had many developments over the recent years, from the early days of men tunnelling, digging and manually extracting the coal on carts, to large open cut and long wall mines. Mining at this scale requires the use of draglines, trucks, conveyors, hydraulic jacks, small-scale mining of surface deposits dates back thousands of years. For example, in Roman Britain, the Romans were exploiting most of the major coalfields by the late 2nd century AD. The Industrial Revolution, which began in Britain in the 18th century and later spread to continental Europe, international trade expanded rapidly when coal-fed steam engines were built for the railways and steamships. Until the late nineteenth century coal was mined using a pick and shovel. Coal-cutting machines were introduced in the 1880s, by 1912, surface mining was conducted with steam shovels designed for coal mining. The most economical method of extraction from coal seams depends on the depth and quality of the seams. Coal mining processes are differentiated by whether they operate on the surface or underground, many coals extracted from both surface and underground mines require washing in a coal preparation plant. Surface mining and deep underground mining are the two methods of mining. Coal that occurs at depths of 180 to 300 ft are usually deep mined, for example, some western U. S. coal that occur at depths in excess of 200 ft are mined by the open pit methods, due to thickness of the seam 60–90 feet. Coals occurring below 300 ft are usually deep mined, However, there are open pit mining operations working on coal seams up to 1000–1500 feet below ground level, for instance Tagebau Hambach in Germany. When coal seams are near the surface, it may be economical to extract the coal using open cut mining methods, open cast coal mining recovers a greater proportion of the coal deposit than underground methods, as more of the coal seams in the strata may be exploited. In this mining method, explosives are first used in order to break through the surface or overburden, the overburden is then removed by draglines or by shovel and truck. Once the coal seam is exposed, it is drilled, fractured, the coal is then loaded onto large trucks or conveyors for transport to either the coal preparation plant or directly to where it will be used
9.
History of coal mining
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The history of coal mining goes back thousands of years. It became important in the Industrial Revolution of the 19th and 20th centuries, Coal mining continues as an important economic activity today. Compared to wood fuels, coal yields a higher amount of energy per mass, though it was used historically as a domestic fuel, coal is now used mostly in industry, especially in smelting and alloy production as well as electricity generation. Coal remains an important energy source because of its low cost and abundance compared to other fuels, Coal is also mined today on a large scale by open pit methods wherever the coal strata strike the surface or are relatively shallow. Britain developed the techniques of underground coal mining from the late 18th century onward, with further progress being driven by 19th century. However, oil and its associated fuels began to be used as alternatives from the 1860s onward, by 2010, coal produced over a fourth of the worlds energy, and by 2050 it is expected to produce about a third. Since 1890, coal mining has also been a political and social issue, early coal extraction was small-scale, the coal lying either on the surface, or very close to it. Typical methods for extraction included drift mining and bell pits, as well as drift mines, small scale shaft mining was used. Both of these techniques however left considerable amount of coal behind. Archeological evidence in China indicates surface mining of coal and household usage after approximately 3490 BC and they are found in Liguria. and in Elis as one approaches Olympia by the mountain road, and they are used by those who work in metals. The earliest known use of coal in the Americas was by the Aztecs who used coal for fuel, in Roman Britain, the Romans were exploiting all major coalfields by the late 2nd century AD. While much of its use remained local, a lively trade developed along the North Sea coast supplying coal to Yorkshire and this also extended to the continental Rhineland, where bituminous coal was already used for the smelting of iron ore. It was used in hypocausts to heat public baths, the baths in military forts, excavation has revealed coal stores at many forts along Hadrians Wall as well as the remains of a smelting industry at forts such as Longovicium nearby. After the Romans left Britain, in AD410, there are no records of coal being used in the country until the end of the 12th century. This commodity, however, was not suitable for use in the type of domestic hearths then in use, as early as 1228, sea coal from the north-east was being taken to London. During the 13th century, the trading of coal increased across Britain and by the end of the century most of the coalfields in England, Scotland and Wales were being worked on a small scale. As the use of coal amongst the artisans became more widespread, it clear that coal smoke was detrimental to health. During the first half of the 14th century coal began to be used for heating in coal producing areas of Britain
10.
Coal-water slurry fuel
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Coal-water slurry fuel is a combustionable mixture of fine coal particles suspended in water. It can be used to power boilers, gas turbines, diesel engines and heating, when coal-water slurry fuel combusts, over ninety-nine percent of its carbon content is consumed. Coal-water slurry fuel is fire-proof and explosion-proof, ash content of less than ten percent is desirable for boilers. For diesel engines, there is no limit, large particle coal-water slurry fuel can be used to produce steam in boilers. Smaller particle coal-water slurry fuel can be used in engines with or without co-fuels. Very small particle coal-water slurry fuel has been trialled in combined cycle gas power plants. Smaller sized particles are more versatile in use but are difficult to produce. Converting coal into a form may simplify the delivery and dispensing of the fuel. It may be a cost-efficient alternative to oil and natural gas, separating non-carbonaceous material before making the slurry may reduce the production of ash to two percent. In the late 1950s, the Soviet Union looked for new methods of using coal sludge for power generation, coal-water slurry fuel was made in a Ball mill which pulverised the coal or coal sludge. This was done near a mine in Belovo, Siberia. The coal-water slurry fuel was transported through a pipeline to Novosibirskaya TEC-5, Novosibirsk, the pipeline had three intermediate pumping stations. The Belovo Novosibirsk project used coal-water slurry fuel in steam boilers at a rate of 1340 tonnes per hour, there was a further project at Belovo Novosibirsk between 1989 and 1993 and development of coal-water slurry fuel technology for district heating stations and power stations. In 2004, a water slurry fuel production plant was opened at Enskiy village. In 2012, the Austrian company, Effective Energy Technology GmbH built facilities for production and combustion of coal-water slurry fuel in Europe, examples of the technology in practice are hydroshock type wet-milling devices and standard water boilers equipped with swirl pre-chamber and coal-water slurry nozzle. Developed by group of companies EET, verkhovna Rada requested China Development Bank credit for the implementation of coal-water slurry fuel technology. Ukteplokom, a state owned entity, commenced operation, Coal dust Pulverized coal-fired boiler Coal slurry NASA Coal fueled diesels for modular power generation Coal fueled diesel emission control
11.
Coal seam fire
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A coal seam fire or mine fire is the underground smouldering of a coal deposit, often in a coal mine. Such fires have economic, social and ecological impacts and they propagate in a creeping fashion along mine shafts and cracks in geologic structures. Because they burn underground, coal fires are extremely difficult and costly to extinguish. There are strong similarities between coal fires and peat fires, across the world, thousands of underground coal fires are burning at any given moment. The problem is most acute in industrializing, coal-rich nations such as China, global coal fire emissions are estimated to cause 40 tons of mercury to enter the atmosphere annually, and to represent three percent of the worlds annual CO2 emissions. Mine fires may begin as a result of an industrial accident, historically, some mine fires were started when bootleg mining was stopped by authorities, usually by blowing the mine up. Of the hundreds of fires in the United States burning today. Some fires along coal seams are natural occurrences, some coals may self-ignite at temperatures as low as 40 °C for brown coal in the right conditions of moisture and grain size. The grain size and structure determine its surface area, kinetics will be limited by availability of reactant, which in this case is carbon exposed to oxygen. Prehistoric clinker outcrops in the American West are the result of coal fires that left a residue that resists erosion better than the matrix, leaving buttes. It is estimated that Australias Burning Mountain, the oldest known coal fire, has burned for 6,000 years, globally, thousands of inextinguishable mine fires are burning, especially in China where poverty, lack of government regulations and runaway development combine to create an environmental disaster. Modern strip mining exposes smoldering coal seams to the air, revitalizing the flames, rural Chinese in coal-bearing regions often dig coal for household use, abandoning the pits when they become unworkably deep, leaving highly combustible coal dust exposed to the air. Using satellite imagery to map Chinas coal fires resulted in the discovery of previously unknown fires. The oldest coal fire in China is in Baijigou and is said to have been burning since the Qing Dynasty, before attempting to extinguish a near-surface coal seam fire, its location and underground extent should be determined as precisely as possible. Besides studying the geographic, geologic and infrastructural context, information can be gained from direct measurements, high resolution optical mapping, thermal imaging and hyperspectral data play a role. Underground coal fires of several hundred to over a thousand degrees Celsius may raise the temperature by only a few degrees. This order of magnitude is similar to the difference between the sunlit and shadowed slopes of a slag heap or sand dune. Infrared detecting equipment is able to track the location as the fire heats the ground on all sides of it
12.
Coal gas
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Coal gas is a flammable gaseous fuel made from coal and supplied to the user via a piped distribution system. Town gas is a general term referring to manufactured gaseous fuels produced for sale to consumers. Town gas was supplied to households via municipally-owned piped distribution systems, originally created as a by-product of the coking process, its use developed during the 19th and early 20th centuries tracking the industrial revolution and urbanization. Facilities where the gas was produced were known as a manufactured gas plant or a gasworks. The production process is distinct, both physically and chemically, from used to create a range of gaseous fuels known variously as manufactured gas, syngas, hygas, Dowson gas. Manufactured gas can be made by two processes, carbonization or gasification, carbonization refers to the devolatilization of an organic feedstock to yield gas and char. Gasification is the process of subjecting a feedstock to chemical reactions that produce gas, the first process used was the carbonization and partial pyrolysis of coal. The off gases liberated in the high-temperature carbonization of coal in coke ovens were collected, scrubbed and used as fuel, Coke plants are typically associated with metallurgical facilities such as smelters, and blast furnaces, while gas works typically served urban areas. A facility used to manufacture coal gas, carburetted water gas, in the early years of MGP operations, the goal of a utility gas works was to produce the greatest amount of illuminating gas. The illuminating power of a gas was related to amount of soot-forming hydrocarbons dissolved in it and these hydrocarbons gave the gas flame its characteristic bright yellow color. Gas works would typically use oily bituminous coals as feedstock and these coals would give off large amounts of volatile hydrocarbons into the coal gas, but would leave behind a crumbly, low-quality coke not suitable for metallurgical processes. Coal or coke oven gas typically had a value between 10 and 20 MJ/m³, with values around 20 MJ/m³ being typical. The advent of electric lighting forced utilities to search for markets for manufactured gas. MGPs that once produced gas almost exclusively for lighting shifted their efforts towards supplying gas primarily for heating and cooking, fuel gas for industrial use was made using producer gas technology. Producer gas is made by blowing air through an incandescent fuel bed in a gas producer, the reaction of fuel with insufficient air for total combustion produces carbon monoxide, this reaction is exothermic and self-sustaining. It was discovered that steam to the input air of a gas producer would increase the calorific value of the fuel gas by enriching it with CO. Producer gas has a very low value of 3.7 to 5. The incandescent fuel bed would be blasted with air followed by steam
