PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES

**Definition:** This place covers:

Processes or apparatus for production of fuel gases by carburetting air or other gases without pyrolysis, including controlling supply of air or liquid, temperature, humidity and other parameters.

Processes or apparatus for production of combustible gases containing carbon monoxide (including producer gas, wood gas, town gas, synthesis gas (syngas), manufactured gas and water gas) from solid carbonaceous materials. This includes fixed-bed gasification of lump fuel, gasification of granular or pulverulent fuels in suspension, gasification using molten salts or metals, carburetting by pyrolysis of carbonaceous material in the fuel bed and carburetting by pyrolysis of carbonaceous material in a carburettor.

**Limiting references (this place does not cover):** - Destructive distillation processes -> C10B - Underground gasification of minerals -> E21B43/295

**Glossary:** - Carburetting: Carburetting air or gas generally comprises passing it in contact with liquid fuel and thereby mixing the air/gas and fuel. This often involves lowering the air pressure e.g. in a venturi. - Destructive distillation: The process of pyrolysis conducted in a distillation apparatus to allow the volatile products to be collected. An example is tar making from pinewood slices (which are rich in terpenes), which are heated in an airless container causing the material to decompose, leaving charcoal and turpentine as by-products. - Gasification: Gasification is somewhat similar to pyrolysis and confusion between these terms is common. Gasification is a partial oxidation process that converts materials such as coal, biomass or plastic waste into a gaseous mixture of carbon monoxide and hydrogen (also known as synthesis gas) by reacting the raw material at high temperatures with controlled amounts of oxygen and/or steam. See also the entry for pyrolysis. - Producer gas: A gas mixture containing carbon monoxide (CO), hydrogen (H 2 ), carbon dioxide (CO 2 ) and nitrogen (N 2 ). In the USA, producer gas is a generic term referring to wood gas, town gas, synthesis gas, syngas or raw gas. In the UK, producer gas, also known as suction gas, means a fuel gas made from coke or other carbonaceous material. Air is passed over the red-hot fuel and carbon monoxide is produced in an exothermic reaction which reads 2C + O 2 → 2CO. The nitrogen in the air remains unchanged and dilutes the gas, so it has a low calorific value. The gas may be used to power gas turbines which are suited to fuels of low calorific value. - Pyrolysis: The chemical decomposition of organic materials by heating in the absence of oxygen or any other reagents, except possibly steam. Pyrolysis is somewhat endothermic and the products can be gases, liquids (e.g. light crude oil from depolymerisation of organic waste) and/or solids (e.g. coke and volatiles produced by coking coal). See also the entry for gasification. - Synthesis gas (syngas): A gas mixture that contains varying amounts of carbon monoxide (CO) and hydrogen (H 2 ) generated by the gasification of a carbon-containing material to a gaseous product with a heating value (but less than half the energy density of natural gas). When used as a fuel, it is produced by gasification of coal or municipal waste by the following reactions: C + O 2 → CO 2 ; CO 2 + C → 2CO; C + H 2 O → CO + H 2 . The name comes from the gas's use as an intermediate in creating synthetic natural gas (SNG) and in producing ammonia or methanol. - Town gas: Also known as coal gas, and contains hydrogen (H 2 ), carbon monoxide (CO), carbon dioxide (CO 2 ), methane (CH 4 ), nitrogen (N 2 ) and volatile hydrocarbons. It is made by blowing air and steam over an incandescent fuel bed, usually of coke or coal. The words "coal gas" could also be used to mean gas made by the destructive distillation of coal. The gas was used inter alia for lighting before the advent of electric lighting, and for heating and cooking before natural gas became widely available. - Water-gas: A mixture of carbon monoxide (CO) and hydrogen (H 2 ) produced by passing steam over red-hot coke using the endothermic reaction C + H 2 O → CO + H 2 . This product had a lower calorific value than coal gas so the gas was often passed through a heated retort into which oil was sprayed; the resulting mixed gas was called carburetted water gas. - Wood gas: The product of thermal gasification of biomass (e.g. coal, wood chips, sawdust, charcoal) in a gasifier or wood gas generator. It is the result of a high temperature reaction (> 700 degrees C) where carbon reacts with steam or a limited amount of air producing carbon monoxide (CO), carbon dioxide (CO 2 ), hydrogen (H 2 ) and methane (CH 4 ). It can be filtered, purified or scrubbed and used to power internal combustion engines, gas turbines, Stirling engines or fuel cells.