Coal gas

Coal gas

Overview
Coal gas is a flammable gaseous fuel made by the destructive distillation
Destructive distillation
Destructive distillation is the chemical process involving the decomposition of feedstock by heating to a high temperature; the term generally applies to processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents,...

 of coal
Coal
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 anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

 containing a variety of calorific gases including hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

, methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

 and volatile hydrocarbons together with small quantities of non-calorific gases such as carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 and nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

. It was the primary source of gaseous fuel both the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 until the widespread adoption of natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

 during the 1940s and 1950s in the US, and the late 1960s and 1970s in the UK.
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Encyclopedia
Coal gas is a flammable gaseous fuel made by the destructive distillation
Destructive distillation
Destructive distillation is the chemical process involving the decomposition of feedstock by heating to a high temperature; the term generally applies to processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents,...

 of coal
Coal
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 anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

 containing a variety of calorific gases including hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

, methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

 and volatile hydrocarbons together with small quantities of non-calorific gases such as carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 and nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

. It was the primary source of gaseous fuel both the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 until the widespread adoption of natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

 during the 1940s and 1950s in the US, and the late 1960s and 1970s in the UK. It was used for lighting, cooking and heating and was often supplied to households via a municipally-owned piped distribution system.

Originally created as a by-product of the coking process, its use developed during the 19th and early 20th centuries tracking the industrial revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

 and urbanization
Urbanization
Urbanization, urbanisation or urban drift is the physical growth of urban areas as a result of global change. The United Nations projected that half of the world's population would live in urban areas at the end of 2008....

. Byproducts from the production process included coal tar
Coal tar
Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...

s and ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 which were important chemical feedstock for the dye and chemical industry
Chemical industry
The chemical industry comprises the companies that produce industrial chemicals. Central to the modern world economy, it converts raw materials into more than 70,000 different products.-Products:...

 with a wide range of artificial dye
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

 colours being made from coal gas and coal tar. Facilities where the gas was produced was often known as a 'Manufactured Gas Plant' or 'MGP'.

Discovery of large reserves of natural gas in the North Sea of the British coast during the early 1960s led to the expensive conversion or replacement of most of the nation's gas cookers and gas heaters, with the exception of Northern Ireland, from the late 1960s onwards.

The production process is distinct, both physically and chemically, from that used to create a range of gaseous fuels known variously as 'manufactured gas', 'syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

', 'hygas', 'Dowson gas' and 'producer gas
Producer gas
-USA:Producer Gas is a generic term referring to:* Wood gas: produced in a gasifier to power cars with ordinary internal combustion engines.* Town gas: manufactured gas, originally produced from coal, for sale to consumers and municipalities....

'. These gases are made by partial combustion of a wide variety of feed stocks in some mixture of air, oxygen or steam, to reduce the latter to hydrogen and carbon dioxide although some destructive distillation
Destructive distillation
Destructive distillation is the chemical process involving the decomposition of feedstock by heating to a high temperature; the term generally applies to processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents,...

 may also occur.

Manufacturing processes



Manufactured gas can be made by two processes: carbonization
Carbonization
Carbonization or carbonisation is the term for the conversion of an organic substance into carbon or a carbon-containing residue through pyrolysis or destructive distillation. It is often used in organic chemistry with reference to the generation of coal gas and coal tar from raw coal...

 or gasification
Gasification
Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...

. Carbonization refers to the devolatilization of an organic feedstock to yield gas and char
Char
Char is the solid material that remains after light gases and tar coal tar have been driven out or released from a carbonaceous material during the initial stage of combustion, which is known as carbonization, charring, devolatilization or pyrolysis.Further stages of efficient combustion are...

. Gasification is the process of subjecting a feedstock to chemical reactions that produce gas.

The first process used was the carbonization and partial pyrolysis
Pyrolysis
Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...

 of coal
Coal
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 anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

. The off gases liberated in the high-temperature carbonization (coking) of coal in coke ovens were collected, scrubbed and used as fuel. Depending on the goal of the plant, the desired product was either a high quality coke
Coke (fuel)
Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

 for metallurgical
Metallurgy
Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. It is also the technology of metals: the way in which science is applied to their practical use...

 use, with the gas being a side product or the production of a high quality gas with coke being the side product. Coke plants are typically associated with metallurgical facilities such as smelters
Smelting
Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction from iron ore, and copper extraction and other base metals from their ores...

, and blast furnace
Blast furnace
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron.In a blast furnace, fuel and ore and flux are continuously supplied through the top of the furnace, while air is blown into the bottom of the chamber, so that the chemical reactions...

s, while gas works typically served urban area
Urban area
An urban area is characterized by higher population density and vast human features in comparison to areas surrounding it. Urban areas may be cities, towns or conurbations, but the term is not commonly extended to rural settlements such as villages and hamlets.Urban areas are created and further...

s.

A facility used to manufacture coal gas, carburetted water gas
Water gas
Water gas is a synthesis gas, containing carbon monoxide and hydrogen. It is a useful product but requires careful handling because of the risk of carbon monoxide poisoning. The gas is made by passing steam over a red-hot hydrocarbon fuel such as coke:...

 (CWG), and oil gas is today generally referred to as a manufactured gas plant (MGP).

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
Soot
Soot is a general term that refers to impure carbon particles resulting from the incomplete combustion of a hydrocarbon. It is more properly restricted to the product of the gas-phase combustion process but is commonly extended to include the residual pyrolyzed fuel particles such as cenospheres,...

-forming hydrocarbons (“illuminants”) dissolved in it. These hydrocarbons gave the gas flame its characteristic bright yellow color. Gas works would typically use oily bituminous coals as feedstock. 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
Metallurgy
Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. It is also the technology of metals: the way in which science is applied to their practical use...

 processes. Coal or coke oven gas typically had a calorific value between 10 and 20 MJ
Joule
The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...

/m³ (250-550 Btu/ft3 (std)); with values around 20 MJ/m³ (550 Btu/ft3 (std)) being typical.

The advent of electric lighting forced utilities to search for other markets for manufactured gas. MGPs that once produced gas almost exclusively for lighting shifted their efforts towards supplying gas primarily for heating and cooking, and even refrigeration
Refrigeration
Refrigeration is a process in which work is done to move heat from one location to another. This work is traditionally done by mechanical work, but can also be done by magnetism, laser or other means...

 and cooling.

Gas for industrial use



Fuel gas for industrial use was made using producer gas technology. Producer gas is made by blowing air through an incandescent fuel bed (commonly coke
Coke (fuel)
Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

 or coal
Coal
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 anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

) in a gas producer. The reaction of fuel with insufficient air for total combustion produces carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

 (CO); this reaction is exothermic and self sustaining. It was discovered that adding steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...

 to the input air of a gas producer would increase the calorific value of the fuel gas by enriching it with CO and hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 (H2) produced by water gas reactions. Producer gas has a very low calorific value of 3.7 to 5.6 MJ/m³ (100-150 Btu/ft3 (std)); because the calorific gases CO/H2 are diluted with lots of inert nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

 (from air) and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 (CO2) (from combustion)

(Exothermic: Producer gas Reaction)

(Endothermic: Water gas
Water gas
Water gas is a synthesis gas, containing carbon monoxide and hydrogen. It is a useful product but requires careful handling because of the risk of carbon monoxide poisoning. The gas is made by passing steam over a red-hot hydrocarbon fuel such as coke:...

 Reaction)

(Endothermic)

(Exothermic: Water gas shift reaction
Water gas shift reaction
The water-gas shift reaction is a chemical reaction in which carbon monoxide reacts with water vapor to form carbon dioxide and hydrogen:The water-gas shift reaction is an important industrial reaction. It is often used in conjunction with steam reforming of methane or other hydrocarbons, which is...

)

The problem of nitrogen dilution was overcome by the blue water gas (BWG) process, developed in the 1850s by Sir William Siemens
Carl Wilhelm Siemens
Carl Wilhelm Siemens was a German born engineer who for most of his life worked in Britain and later became a British subject.-Biography:...

. The incandescent fuel bed would be alternately blasted with air followed by steam. The air reactions during the blow cycle are exothermic, heating up the bed, while the steam reactions during the make cycle, are endothermic and cool down the bed. The products from the air cycle contain non-calorific nitrogen and are exhausted out the stack while the products of the steam cycle are kept as blue water gas. This gas is composed almost entirely of CO and H2, and burns with a pale blue flame similar to natural gas. BWG has a calorific value of 11 MJ/m³ (300 Btu/ft3 (std)).

Because blue water gas lacked illuminants, it would not burn with a luminous flame in a simple fishtail gas jet as existed prior to the invention of the Welsbach mantle
Gas mantle
An incandescent gas mantle, gas mantle, or Welsbach mantle is a device for generating bright white light when heated by a flame. The name refers to its original heat source, existing gas lights, which filled the streets of Europe and North America in the late 19th century, mantle referring to the...

 in the 1890s. Various attempts were made to enrich BWG with illuminants from gas oil in the 1860s. Gas oil (an early form of gasoline) was the flammable waste product from kerosene
Kerosene
Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...

 refining, made from the lightest and most volatile fractions (tops) of crude oil.
In 1875 Thaddeus S. C. Lowe invented the carburetted water gas process. This process revolutionized the manufactured gas industry and was the standard technology until the end of manufactured gas era. A CWG generating set consisted of three elements; a producer (generator), carburettor and a super heater connected in series with gas pipes and valves.

During a make run, steam would be passed through the generator to make blue water gas. From the generator the hot water gas would pass into the top of the carburetor where light petroleum oils would be injected into the gas stream. The light oils would be thermocracked as they came in contact with the white hot checkerwork fire brick
Fire brick
A fire brick, firebrick, or refractory brick is a block of refractory ceramic material used in lining furnaces, kilns, fireboxes, and fireplaces. A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency...

s inside the carburettor. The hot enriched gas would then flow into the superheater, where the gas would be further cracked by more hot fire bricks.

War and Post-War Britain


The post-war house building programme put gas at a disadvantage. Whereas electricity had long developed a national distribution grid, which enabled supplies to reach even small new housing developments, gas was still distributed only locally. Many new housing estates were beyond the reach of the gas main and the stringent Treasury
HM Treasury
HM Treasury, in full Her Majesty's Treasury, informally The Treasury, is the United Kingdom government department responsible for developing and executing the British government's public finance policy and economic policy...

 rules about return on investment
Return on investment
Return on investment is one way of considering profits in relation to capital invested. Return on assets , return on net assets , return on capital and return on invested capital are similar measures with variations on how “investment” is defined.Marketing not only influences net profits but also...

 made extension of mains uneconomic. Electricity made inroads into the home heating market with underfloor heating
Underfloor heating
Underfloor heating and cooling is a form of central heating and cooling which achieves indoor climate control for thermal comfort using conduction, radiation and convection...

 and night storage heaters using cheap off-peak electricity supplies.

By the 1960s, manufactured gas, compared with its main rival in the energy market, electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

, was considered "nasty, smelly, dirty and dangerous" (to quote market research of the time) and seemed doomed to lose market share still further, except for cooking where its controllability gave it marked advantages over both electricity and solid fuel. The development of more efficient gas fires assisted gas to resist competition in the market for room heating. Concurrently a new market for whole house central heating
Central heating
A central heating system provides warmth to the whole interior of a building from one point to multiple rooms. When combined with other systems in order to control the building climate, the whole system may be a HVAC system.Central heating differs from local heating in that the heat generation...

 by hot water was being developed by the oil industry and the gas industry followed suit. Gas warm air heating found a market niche in new local authority housing where low installation costs gave it an advantage. These developments, the realignment of managerial thinking away from commercial management
Management
Management in all business and organizational activities is the act of getting people together to accomplish desired goals and objectives using available resources efficiently and effectively...

 (selling what the industry produced) to marketing
Marketing
Marketing is the process used to determine what products or services may be of interest to customers, and the strategy to use in sales, communications and business development. It generates the strategy that underlies sales techniques, business communication, and business developments...

 management (meeting the needs and desires of customers) and the lifting of an early moratorium preventing nationalised industries from using television advertising, saved the gas industry for long enough to provide a viable market for what was to come.

Change over to natural gas


In 1959 the British Gas Council demonstrated that liquid natural gas (LNG) could be transported safely, efficiently and economically over long distances by sea. The 'Methane Pioneer' shipped a consignment of LNG from Lake Charles, Louisiana
Lake Charles, Louisiana
Lake Charles is the fifth-largest incorporated city in the U.S. state of Louisiana, located on Lake Charles, Prien Lake, and the Calcasieu River. Located in Calcasieu Parish, a major cultural, industrial, and educational center in the southwest region of the state, and one of the most important in...

, USA, to a new LNG terminal on Canvey Island
Canvey Island
Canvey Island is a civil parish and reclaimed island in the Thames estuary in England. It is separated from the mainland of south Essex by a network of creeks...

 and customers there were converted to use the new fuel. A 320 miles (515 km) long high-pressure trunk pipeline was built from London to Leeds.

The slow death of the town gas industry in the UK was signalled by the discovery of natural gas, by the ill-fated BP drilling rig Sea Gem
Sea Gem
The Sea Gem was the first British offshore oil rig, and the first British offshore rig disaster when in 1965, the rig's legs collapsed, killing 13 of the crew.-Background:...

on 17 September 1965 some forty miles off Grimsby
Grimsby
Grimsby is a seaport on the Humber Estuary in Lincolnshire, England. It has been the administrative centre of the unitary authority area of North East Lincolnshire since 1996...

, over 8000 feet (2,438.4 m) below the sea bed. Subsequently the North Sea was found to have many rich gas fields on both sides of the median line which defined which nations should have rights over the reserves.

The Fuel Policy White Paper
White paper
A white paper is an authoritative report or guide that helps solve a problem. White papers are used to educate readers and help people make decisions, and are often requested and used in politics, policy, business, and technical fields. In commercial use, the term has also come to refer to...

 of 1967 (Cmd. 3438) pointed the industry in the direction of building up the use of natural gas speedily to 'enable the country to benefit as soon as possible from the advantages of this new indigenous energy source'. As a result, there was a 'rush to gas' for use in peak load electricity generation and in low grade uses in industry. The effects on the coal industry were very significant; not only did coal lose its market for town gas production, it came to be displaced from much of the bulk energy market also.

The exploitation of the North Sea gas reserves
North Sea oil
North Sea oil is a mixture of hydrocarbons, comprising liquid oil and natural gas, produced from oil reservoirs beneath the North Sea.In the oil industry, the term "North Sea" often includes areas such as the Norwegian Sea and the area known as "West of Shetland", "the Atlantic Frontier" or "the...

, entailing landing gas at Easington
Easington, East Riding of Yorkshire
Easington is a small village and civil parish in the East Riding of Yorkshire, England in the area known as Holderness. It is situated between the Humber estuary and the North Sea at the south-eastern corner of the county at the end of the B1445 road from Patrington.The civil parish is formed by...

, Bacton
Bacton, Norfolk
Bacton is a village and civil parish in Norfolk, England. It is on the Norfolk coast, some 20 km south-east of Cromer, 40 km north-west of Great Yarmouth and 30 km north of Norwich. Besides the village of Bacton, the parish includes the nearby settlements of Bacton Green, Broomholm,...

 and St Fergus made viable the building of a national distribution grid, of over 3000 miles (4,828 km), consisting of two parallel and interconnected pipelines running the length of the country. All gas equipment in the whole of the UK (but not Northern Ireland) was converted (by the fitting of different-sized burner jets to give the correct gas/air mixture) from burning town gas to burn natural gas (mainly methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

) over the period from 1967 to 1977 at a cost of about £100 million including the writing off of redundant town gas manufacturing plants. All the gas-using equipment of almost 13 million domestic, 400 thousand commercial, and 60 thousand industrial customers, was converted. Many dangerous appliances were discovered in this exercise and were taken out of service. The British town gas industry died in 1987 when operations ceased at the last town gas manufacturing plants in Northern Ireland. (Belfast, Portadown and Carrickfergus) Carrickfergus gas works is now a restored gas works museum. The Portadown site has been cleared and is now the subject of a long term experiment into the use of bacteria for the purpose of cleaning up contaminated industrial land. As well as requiring little processing before use, natural gas is non-toxic; the carbon monoxide (CO) in town gas made it extremely poisonous, accidental poisoning and suicide by gas being commonplace. Poisoning from natural gas appliances is only due to incomplete combustion, which creates CO, and flue leaks to living accommodation. As with town gas, a small amount of foul-smelling substance (mercaptan) is added to the gas to indicate to the user that there is a leak or an unlit burner, the gas having no odour of its own.

The organisation of the British gas industry adapted to these changes, first, by the Gas Act 1965 by empowering the Gas Council to acquire and supply gas to the twelve area Boards. Then, the Gas Act 1972 formed the British Gas Corporation as a single commercial entity, embracing all the twelve Area Gas Boards, allowing them to acquire, distribute and market gas and gas appliances to industrial commercial and domestic customers throughout the UK. In 1986, British Gas
British Gas plc
British Gas plc was formerly the monopoly gas supplier and is a private sector in the United Kingdom.- History :In the early 1900s the gas market in the United Kingdom was mainly run by county councils and small private firms...

 was privatised and dismembered and the Government no longer has any direct control over it. The most recent demergers are described at http://www.britishgas.co.uk/

During the era of North Sea gas
North Sea oil
North Sea oil is a mixture of hydrocarbons, comprising liquid oil and natural gas, produced from oil reservoirs beneath the North Sea.In the oil industry, the term "North Sea" often includes areas such as the Norwegian Sea and the area known as "West of Shetland", "the Atlantic Frontier" or "the...

, many of the original cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

 gas pipes
Piping
Within industry, piping is a system of pipes used to convey fluids from one location to another. The engineering discipline of piping design studies the efficient transport of fluid....

 installed in towns and cities for town gas were replaced by plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

.

As reported in the DTI Energy Review 'Our Energy Challenge' January 2006 North Sea gas resources have been depleted at a faster rate than had been anticipated and gas supplies for the UK are being sought from remote sources, a strategy made possible by developments in the technologies of pipelaying that enable the transmission of gas over land and under sea across and between continents. Natural gas is now a world commodity
Commodity
In economics, a commodity is the generic term for any marketable item produced to satisfy wants or needs. Economic commodities comprise goods and services....

. Such sources of supply are exposed to all the risks of any import. There are still substantial coal reserves in the UK and this fact prompts the thought that at some time in the future, coal gas may once again be used as a reliable indigenous source of energy.

Gas production in Germany


In many ways, Germany took the lead in coal gas research and carbon chemistry.
With the labours of Hofmann, the whole German chemical industry emerged.
Using the coal gas waste as feedstock, researchers developed new processes and synthesized
natural organic compounds such as vitamin C and aspirin.

The German economy relied on coal gas during the Second World War as petroleum shortages forced
Nazi Germany to develop the Fischer-Tropsch synthesis to produce synthetic fuel for aircraft and tanks.

Development of Pacific coast oil gas process



The Pacific coast process has significant problems with lampblack. 20 to 30 lb/1000 ft³ (300 to 500 g/m³) of oily soot can be created during combustion. Major pollution problems led to the passage of early state-level environmental legislation.

Layout of a typical gas plant

  • 1880s Coal gasification plant.

  • 1910 CWG plant


Issues in gas processing

  • Tar aerosols (tar extractors, condensers/scrubbers, Electrostatic precipitators in 1912)
  • Light oil vapors (oil washing)
  • Naphthalene
    Naphthalene
    Naphthalene is an organic compound with formula . It is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings...

     (oil/tar washing)
  • Ammonia
    Ammonia
    Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

     gas (scrubbers)
  • Hydrogen sulfide
    Hydrogen sulfide
    Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...

     gas (purifier boxes)
  • Hydrogen cyanide gas (purifier)

WWI-interwar era developments

  • Loss of high-quality gas oil (used as motor fuel) and feed coke (diverted for steelmaking) leads to massive tar problems. CWG tar is less valuable than coal gasification tar as a feed stock. Tar-water emulsions are uneconomical to process due to unsellable water and lower quality by products.
CWG tar is full of lighter PAH's, good for making pitch, but poor in chemical precursors.
  • Various "back-run" procedures for CWG generation lower fuel consumption and help deal with issues from the use of bitumious coal in CWG sets.
  • Development of high-pressure pipeline welding encourages the creation of large municipal gas plants and the consolidation of the MG industry. Sets the stage for rise natural gas
    Natural gas
    Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

    .
  • Electric lighting replaces gaslight. MG industry peak is sometime in mid 1920s.
  • 1936 or so. Development of Lurgi gasifier. Germans continue work on gasification/synfuels due to oil shortages.

  • The Public Utility Holding Company Act of 1935
    Public Utility Holding Company Act of 1935
    The Public Utility Holding Company Act of 1935 , , also known as the Wheeler-Rayburn Act, was a law that was passed by the United States Congress to facilitate regulation of electric utilities, by either limiting their operations to a single state, and thus subjecting them to effective state...

    , in the USA, forces break up of integrated coke and gas companies in the United States.
  • Fischer-Tropsch process for synthesis of liquid fuels from / gas.
  • Haber-Bosch ammonia process
    Haber process
    The Haber process, also called the Haber–Bosch process, is the nitrogen fixation reaction of nitrogen gas and hydrogen gas, over an enriched iron or ruthenium catalyst, which is used to industrially produce ammonia....

     creates a large demand for industrial hydrogen.

Post WWII: the decline of manufactured gas

  • Development of natural gas industry. NG is 37 MJ/m³
  • Petrochemicals kill much of the value coal tar as a source of chemical feed stocks. (BTX, Phenols, Pitch)
  • Decline in creosote
    Creosote
    Creosote is the portion of chemical products obtained by the distillation of a tar that remains heavier than water, notably useful for its anti-septic and preservative properties...

     use for wood preserving.
  • Direct coal
    Coal
    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 anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

    /natural gas
    Natural gas
    Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

     injection reduces demand for metallurgical coke. 25 to 40% less coke is needed in blast furnaces.
  • BOF and EAF processes obsolete cupola furnace
    Cupola furnace
    A Cupola or Cupola furnace is a melting device used in foundries that can be used to melt cast iron, ni-resist iron and some bronzes. The cupola can be made almost any practical size. The size of a cupola is expressed in diameters and can range from . The overall shape is cylindrical and the...

    s. Reduce need for coke in recycling steel scrap. Less need for fresh steel/iron.
  • Cast iron
    Cast iron
    Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

     & steel
    Steel
    Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

     are replaced with aluminum and plastics.
  • Pthalic anhydride production shifts from catalytic oxidation of naphthalene to o-xylol process.

Post WWII positive developments

  • Catalytic upgrading of gas by use of hydrogen to react with tarry vapors in the gas
  • The decline of coke making in the US leads to a coal tar crisis since coal tar pitch is vital for the production of carbon electrodes for EAF/Aluminum. US now has to import CT from china
  • Development of process to make methanol via hydrogenation of CO/H2 mixtures.
  • Mobil M-gas process for making gasoline from methanol
  • SASOL
    Sasol
    Sasol Ltd. is a South African company involved in mining, energy, chemicals and synfuels. In particular, they produce petrol and diesel profitably from coal and natural gas using Fischer-Tropsch process...

     coal process plant in South Africa.
  • Direct hydrogenation of coal into liquid and gaseous fuels

Terminology in the UK


In British usage
British English
British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...

, coal gas specifically means gas made by the destructive distillation
Destructive distillation
Destructive distillation is the chemical process involving the decomposition of feedstock by heating to a high temperature; the term generally applies to processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents,...

 of coal. The term is not applied to other coal-derived gases, such as water gas
Water gas
Water gas is a synthesis gas, containing carbon monoxide and hydrogen. It is a useful product but requires careful handling because of the risk of carbon monoxide poisoning. The gas is made by passing steam over a red-hot hydrocarbon fuel such as coke:...

, producer gas
Producer gas
-USA:Producer Gas is a generic term referring to:* Wood gas: produced in a gasifier to power cars with ordinary internal combustion engines.* Town gas: manufactured gas, originally produced from coal, for sale to consumers and municipalities....

 and syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

. United States usage
American English
American English is a set of dialects of the English language used mostly in the United States. Approximately two-thirds of the world's native speakers of English live in the United States....

 may be different.

Coal gas was introduced in the UK in the 1790s as an illuminating gas by the Scottish
Scottish people
The Scottish people , or Scots, are a nation and ethnic group native to Scotland. Historically they emerged from an amalgamation of the Picts and Gaels, incorporating neighbouring Britons to the south as well as invading Germanic peoples such as the Anglo-Saxons and the Norse.In modern use,...

 inventor William Murdoch
William Murdoch
William Murdoch was a Scottish engineer and long-term inventor.Murdoch was employed by the firm of Boulton and Watt and worked for them in Cornwall, as a steam engine erector for ten years, spending most of the rest of his life in Birmingham, England.He was the inventor of the oscillating steam...

 and became very widely used for lighting, cooking, heating and powering gas engine
Gas engine
A gas engine means an engine running on a gas, such as coal gas, producer gas biogas, landfill gas, or natural gas. In the UK, the term is unambiguous...

s.

Manufacture


Coal was heated in a retort
Retort
In a chemistry laboratory, a retort is a glassware device used for distillation or dry distillation of substances. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated...

 and the crude gas was passed through a condenser
Condenser (heat transfer)
In systems involving heat transfer, a condenser is a device or unit used to condense a substance from its gaseous to its liquid state, typically by cooling it. In so doing, the latent heat is given up by the substance, and will transfer to the condenser coolant...

 to remove tar and a scrubber
Scrubber
Scrubber systems are a diverse group of air pollution control devices that can be used to remove some particulates and/or gases from industrial exhaust streams. Traditionally, the term "scrubber" has referred to pollution control devices that use liquid to wash unwanted pollutants from a gas stream...

 to remove other impurities. The residue remaining in the retort was coke.

Composition


The composition of coal gas varied according to the type of coal and the temperature of carbonisation. Typical figures were:
  • hydrogen
    Hydrogen
    Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

     50%
  • methane
    Methane
    Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

     35%
  • carbon monoxide
    Carbon monoxide
    Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

     10%
  • ethylene
    Ethylene
    Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...

     5%


In a plain burner, only the ethylene produced a luminous flame but the light output could be greatly increased by using a gas mantle
Gas mantle
An incandescent gas mantle, gas mantle, or Welsbach mantle is a device for generating bright white light when heated by a flame. The name refers to its original heat source, existing gas lights, which filled the streets of Europe and North America in the late 19th century, mantle referring to the...

.

By-products


The by-products of coal gas manufacture included coke
Coke (fuel)
Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

, coal tar
Coal tar
Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...

, sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 and ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 and these were all useful products.
Dyes, medicines such as sulfa drugs, saccharine and sugar free soda drink, and dozens of organic compounds are made from coal gas.

Coke


Coke
Coke (fuel)
Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

 is used as a smokeless fuel and for the manufacture of water gas
Water gas
Water gas is a synthesis gas, containing carbon monoxide and hydrogen. It is a useful product but requires careful handling because of the risk of carbon monoxide poisoning. The gas is made by passing steam over a red-hot hydrocarbon fuel such as coke:...

 and producer gas
Producer gas
-USA:Producer Gas is a generic term referring to:* Wood gas: produced in a gasifier to power cars with ordinary internal combustion engines.* Town gas: manufactured gas, originally produced from coal, for sale to consumers and municipalities....

.

Coal tar


Coal tar
Coal tar
Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...

 was subjected to fractional distillation
Fractional distillation
Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. It is a special type of distillation...

 to recover various products, including
  • tar
    Tar
    Tar is modified pitch produced primarily from the wood and roots of pine by destructive distillation under pyrolysis. Production and trade in tar was a major contributor in the economies of Northern Europe and Colonial America. Its main use was in preserving wooden vessels against rot. The largest...

    , for roads
  • benzole
    Benzole
    In the United Kingdom, the word benzole means a coal-tar product, consisting mainly of benzene and toluene. It was formerly mixed with petrol and sold as a motor fuel under trade names including "National Benzole Mixture" and "Regent Benzole Mixture"....

    , a motor fuel
  • creosote
    Creosote
    Creosote is the portion of chemical products obtained by the distillation of a tar that remains heavier than water, notably useful for its anti-septic and preservative properties...

    , a wood preservative
  • phenol
    Phenol
    Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...

    , used in the manufacture of plastic
    Plastic
    A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

    s
  • cresol
    Cresol
    Cresols are organic compounds which are methylphenols. They are a widely occurring natural and manufactured group of aromatic organic compounds which are categorized as phenols . Depending on the temperature, cresols can be solid or liquid because they have melting points not far from room...

    s, disinfectants

Structure of the industry


Coal gas was initially manufactured by independent companies but many of these later became municipal services
Municipal services
Municipal services or city services refer to basic services that residents of a city expect the city government to provide in exchange for the taxes which citizens pay. Basic city services may include sanitation , water, streets, schools, food inspection fire department, police, ambulance, and...

. Both the private and the municipal companies were nationalised
Nationalization
Nationalisation, also spelled nationalization, is the process of taking an industry or assets into government ownership by a national government or state. Nationalization usually refers to private assets, but may also mean assets owned by lower levels of government, such as municipalities, being...

 under The Gas Act 1948 and further re-structuring took place under The Gas Act 1972. For further details see British Gas plc
British Gas plc
British Gas plc was formerly the monopoly gas supplier and is a private sector in the United Kingdom.- History :In the early 1900s the gas market in the United Kingdom was mainly run by county councils and small private firms...

.

Coal gas is no longer made in the UK. It was replaced first by gas made from oil and later by natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

 from the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

.

See also

  • Environmental remediation
  • Gas lighting
    Gas lighting
    Gas lighting is production of artificial light from combustion of a gaseous fuel, including hydrogen, methane, carbon monoxide, propane, butane, acetylene, ethylene, or natural gas. Before electricity became sufficiently widespread and economical to allow for general public use, gas was the most...

  • Gas Works Park
    Gas Works Park
    Gas Works Park in Seattle, Washington is a 19.1 acre public park on the site of the former Seattle Gas Light Company gasification plant, located on the north shore of Lake Union at the south end of the Wallingford neighborhood. Gas Works park contains remnants of the sole remaining coal...

  • Gasification
    Gasification
    Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...

  • gasifier
  • History of manufactured gas
    History of manufactured gas
    The history of manufactured gas, important for lighting, heating, and cooking purposes throughout most of the nineteenth century and the first half of the 20th century, began with the development of analytical and pneumatic chemistry in the eighteenth century...

  • Illuminating gas
  • Natural gas
    Natural gas
    Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

  • pyrolysis
    Pyrolysis
    Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...

  • Syngas
    Syngas
    Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

  • Wood gas
    Wood gas
    Wood gas is a syngas fuel which can be used as a fuel for furnaces, stoves and vehicles in place of petrol, diesel or other fuels. During the production process biomass or other carbon-containing materials is gasified within the oxygen-limited environment of a wood gas generator to produce hydrogen...

  • Gasometer
    Gasometer
    A gas holder is a large container where natural gas or town gas is stored near atmospheric pressure at ambient temperatures. The volume of the container follows the quantity of stored gas, with pressure coming from the weight of a movable cap...


Sources

  • Everard, Stirling (1949). The History of the Gas Light and Coke Company 1812-1949. London: Ernest Benn Limited. (Reprinted 1992, London: A&C Black (Publishers) Limited for the London Gas Museum. ISBN 0-7136-3664-5).