Coal gas
Town gas or coal gas refers to a since the mid-19th century, widely available fuel, which was mostly produced in urban Directed by coal gasification. It was used for lighting streets and homes and there also for the operation of gas stoves and gas water heaters. Town gas in public gas grid was in Europe in the second half of the 20th century, replaced by natural gas - with stand 2012 There are only sporadically in China powered by town gas gas networks.
Composition
City gas is a gas mixture of different gases, represents the exact composition varies depending on the gas plant and production process, the type of gas purification and of the coal used. For the former gasworks Vienna Simmering the composition of city gas is specified as follows:
- Hydrogen H2 (51%)
- Methane CH4 (21%)
- Nitrogen N2 (15%)
- Carbon monoxide CO (9%)
In addition, various other gases are present in traces, including small amounts of water vapor, and traces of carbon dioxide, CO2, O2 oxygen and hydrocarbons CmHn.
The town gas was - like acetylene - added in very small quantities significantly garlic smelling diphosphine, so avoid leaks could be detected from the fact (see also odorisation ).
In order to increase the calorific value of pure coal gas, town gas at the beginning of the 20th century was also water gas composed primarily of carbon monoxide and hydrogen gas, mixed. After the second world war was started to reduce the toxic Kohlenstoffmonoxidanteil and reinforced admix the city gas natural gas ( methane). Also through these additional admixtures changed depending on the gas and period, the percentage of the individual gases.
Production
Town gas is produced by degassing of coal under exclusion of air in retorts or furnaces. Similarly, the method for generating water gas and producer gas in coke ovens are. Coker gas consists mainly of hydrogen, methane and carbon monoxide.
Town gas is toxic because of the carbon monoxide fraction and is no longer manufactured in Germany. The carbon monoxide content in the town gas led to suicidal abuse ( " opening the throttle valve "). Today, natural gas is a combustible gas technically relatively straightforward for making it a coal gasification for town gas production unnecessary. City gas is, however, still continue to be used in countries with large coal reserves and no significant gas reserves ( eg China) in households.
In West Berlin, the gas supply was only changed in the 1990s from town gas to natural gas. Until then, the town gas from natural gas was produced in a special process. In Vienna and Augsburg ( refer particularly gasworks Augsburg), for example, the transition was made, however, in a long-lasting process, from 1969 until 1978. Case of upgrading, had to be replaced at the respective combustion technology because of different heating value and the different operating pressure, the nozzle and the seals, or the equipment has been replaced with new ones that were designed for natural gas. There was also the problem that seals dried up by the city compared to the gas rather dry natural gas from hemp and these were leaking it.
History
The history begins with the discovery of coal gases in the early days of modern chemistry. The Flemish scientist Johan Baptista van Helmont (1577-1644) discovered a " wild spirit " that emanated from heated wood and coal, and described it in his book " Origins of Medicine" (1609 ) as "gas " (derived from chaos). Similar experiments were performed independently in other regions, such as Johann Becker in Munich ( 1681) and John Clayton in Wigan in England ( 1684). The latter used the " coal spirit " to the salon entertainment. The first functional gas lighting invented William Murdoch (later Murdock ) ( 1754-1839 ), is the reputed to have first heated coal in the kettle the mother to produce coal gas. He explored the processes of production, purification and storage on - first he lit his house in Redruth (1792 ), then the entrance of the police headquarters in Manchester (1797 ), later the factory premises of Boulton and Watt in Birmingham and finally the large spinning mill in Salford in Lancashire in 1805.
Professor Johannes Petrus Minckeleers lit his lecture room at the University of Leuven since 1783, and Lord Dundonald lit his house in Culross in Scotland since 1787, the gas was been transported in sealed tank cars from the local coking plant. In France, Philippe Lebon, the gas lighting in 1799 was patented in 1801 and demonstrated the use of street lighting. Other examples are abundant in France and the United States, the first commercial gas work was however not until 1812 in the Great Peter Street by the London and Westminster Gas Light and Coke Company ( illuminating gas and Kokswerke London - Westminster ), the coal gases through wooden pipes to Westminster Bridge were passed and since New Year's Day 1813 inflamed gas lamps. In the U.S., Rembrandt Peale established with four partners, the Gas Light Company of Baltimore ( coal gas plants Baltimore) on the basis of city gas as was used in Fredonia in upstate New York since 1821 natural gas. The first gas plants in Germany were built in 1825 in Hannover - by 1870 there were already more than 340 gas stations in Germany, the town gas from coal, wood, peat, and other materials won.
The first supply of compressed gas lines was 1807 in London, making thirteen gas lamps were fired at three gas nozzles in glass lamps used to light the Pall Mall in length. This goes back to the inventor and entrepreneur Fredrick Winsor and the locksmith Thomas Sugg who established the pipes and relocated. The next placement in private households was mainly hampered by rights of way that had to be procured with difficulty for the laying of pipes under the road. Without these barriers could provide wide area with illuminating gas William Murdock and his student Samual Clegg.
In the 1850s, the production of water gas was from the gas works then switched, so now instead of coke directly coal could be used as raw material. 1860 showed the BWG- process ( blue water gas, invented in 1850 by Carl Wilhelm Siemens) the use of kerosene gases produced in the refining of gasoline substances for use as illuminating gas. Instead of the usual production process, which resembled those of a coking plant, showed Prof. Thaddeus SC Lowe in 1875 the production of water gas of air. The CWG process was then the normal method for town gas production from the 1880s to about the 1950s - the resulting city gas has a calorific value of about 20 MJ / m³, which corresponds to about half of natural gas ( 37 MJ / m³). With the development of the mantle by Carl Auer von Welsbach in 1885, the light from gas lamps, now with much higher luminosity was also competitive on electric lighting.
The use of illuminating gas had far-reaching social effects. First, it concerned the industrial production, whose works were lit in the middle of the 18th century first, and there a significant extension of working hours in the works enabled to continuous night shifts (especially in the spinning mills in England). In addition, the street lights allowed an extended urban traffic, but also reading books spread as evening employment. Gas works were created in almost every city in the United Kingdom, the illuminated over -pressure gas lines, the cities - with the invention of the gas meter in the late 1880s was city gas then common in private homes and found increasingly other use also because as illuminating gas.
The use of town gas for heating is a result of the use of fuel oil for firing from kettles, which then serve as a central heating residential buildings. Their flames could also be replaced by gas flames. In the period of commercial use of town gas but this was also in constant competition with the electricity, hazardous, easier to handle in comparison as clean and without odor was perceived. Thus, the use of city gas was pushed further and further as the light source and remained mainly for cooking and heating.
The decline of the town gas production is a result of the discovery of natural gas deposits in Europe, especially in the North Sea and Central Europe, the construction of gas pipelines from far -lying deposits, such as from Russia. In Britain, the changeover in 1967 decided on natural gas and finished with state funding until 1977 - it was 13 million households, 400,000 businesses and 60,000 industrial enterprises changed ( including some dangerous constructions discovered and were put out of service ), and ended on September 1, 1977 in the conversion of a gas lighting system in Edinburgh. In West Berlin, the supply has been suspended until the reunification of the city gas reasons. It was not until 1996, the last consumer were converted to natural gas.