Producer gas is fuel gas that is manufactured from material such as coal, as opposed to natural gas. It can be produced from various fuels by partial combustion with air, usually modified by injection of water or steam to maintain a constant temperature and obtain a higher heat content gas by enrichment of air gas with hydrogen. In this respect it is similar to other types of "manufactured" gas, such as coal gas, coke oven gas, water gas and carburetted water gas. Producer gas was used primarily as an industrial fuel for iron and steel manufacturing, such as firing coke ovens and blast furnaces, cement and ceramic kilns, or for mechanical power through gas engines. It was characteristically low in heating value but cheap to make, so that large amounts could be made and burned.
In the USA, producer gas may also be referred to by other names based on the fuel used for production such as wood gas. In the UK, producer gas is generally referred to as suction gas. The term suction refers to the way the air was drawn into the gas generator by an internal combustion engine.
Wood gas is produced in a gasifier and used to fire kilns, but the gas generated contains distillates that require scrubbing for use in other applications. Depending on the fuel, a variety of contaminants are produced that will condense out as the gas cools. When producer gas is used to power cars and boats or distributed to remote locations it is necessary to scrub the gas to remove the materials that can condense and clog carburettors and gas lines. Anthracite and coke are preferred for automotive use because they produce the smallest amount of contamination, allowing smaller, lighter scrubbers to be used.
Producer gas is generally made from coke, or other carbonaceous material such as anthracite. Air is passed over the red-hot carbonaceous fuel and carbon monoxide is produced. The reaction is exothermic and proceeds as follows:
Formation of producer gas from air and carbon:
Reactions between steam and carbon:
Reaction between steam and carbon monoxide:
The average composition of ordinary producer gas according to Latta was: CO2: 5.8%; O2: 1.3%; CO: 19.8%; H2: 15.1%; CH4: 1.3%; N2: 56.7%; B.T.U. gross per cu.ft 136  The concentration of carbon monoxide in the "ideal" producer gas was considered to be 34.7% carbon monoxide (carbonic oxide) and 65.3% nitrogen. After "scrubbing", to remove tar, the gas may be used to power gas turbines (which are well-suited to fuels of low calorific value), spark ignited engines (where 100% petrol fuel replacement is possible) or diesel internal combustion engines (where 15% to 40% of the original diesel fuel requirement is still used to ignite the gas ). During World War II in Britain, plants were built in the form of trailers for towing behind commercial vehicles, especially buses, to supply gas as a replacement for petrol (gasoline) fuel. A range of about 80 miles for every charge of anthracite was achieved.
In old movies and stories, when describing suicide by "turning on the gas" and leaving an oven door open without lighting the flame, the reference was to coal gas or town gas. As this gas contained a significant amount of carbon monoxide it was quite toxic. Most town gas was also odorized, if it did not have its own odor. Modern 'natural gas' used in homes is far less toxic, and has a mercaptan added to it for odor for identifying leaks.
Various names are used for producer gas, air gas and water gas generally depending on the fuel source, process or end use including:
Other similar fuel gasses
Uses and Advantages of Producer Gas:
American producer gas practice and industrial gas engineering.
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