GB711208A - Improvements in or relating to the pyrolysis and/or cracking of organic substances - Google Patents

Abstract

Pyrolysis and/or cracking of substantially saturated hydrocarbons (e.g. methane and ethane) to acetylene is carried out by feeding the saturated hydrocarbon together with air or oxygen into the combustion chamber of an internal combustion gas turbine system, heating the mixture to initiate the conversion, and rapidly cooling the reacting mixture by expansion in the turbine in order to prevent undesired conversion of the acetylene; the amount of saturated hydrocarbon employed is far in excess of that required for complete combustion relative to the oxygen present. An inert gas, e.g. carbon dioxide or nitrogen, or a volatile liquid, may be introduced into the gas stream to lower the temperature or reduce the partial pressure of the reacting gases; the gases issuing from turbine may be cooled by a spray of water or of a selective solvent such as acetone. Modifying agents, e.g. ethylene dibromide, or combustion promoters, e.g. ethyl nitrate or nitrite, may be introduced at any point of the system. Combustion may be stopped at a desired point by a porous flame trap coated, for example, with potassium chloride. Further quantities of hydrocarbon and oxygen may be fed into the turbine system at a point beyond the initial feed point; alternatively the hydrocarbon with or without oxygen may be fed into a combusted or partially combusted fuel-oxygen mixture. Combustion may take place at the interface between a stream of hydrocarbon and a parallel stream of oxygen-containing gas. The turbine parts may be cooled by "sweat cooling" as described in Specification 619,634, [Group XXVI], using, for example, the hydrocarbon to be converted as the fluid. Low pressures may be maintained in the system by connecting the outlet to an exhauster driven by the turbine or by providing for supersonic flow between the combustion chamber and the turbine by means of specially designed ducts.ALSO:Pyrolysis and/or cracking of substantially saturated hydrocarbons (e.g. methane and ethane) to unsaturated hydrocarbons (e.g. acetylene and ethylene) is carried out by feeding the saturated hydrocarbon together with air or oxygen into the combustion chamber of an internal combustion gas turbine system, heating the mixture to initiate the conversion, and rapidly cooling the reacting mixture by expansion in the turbine in order to prevent undesired conversion of the unsaturated hydrocarbons; the amount of saturated hydrocarbon employed is far in excess of that required for complete combustion relative to the oxygen present. An inert gas, e.g. carbon dioxide or nitrogen, or a volatile liquid, may be introduced into the gas stream to lower the temperature or reduce the partial pressure of the reacting gases; the gases issuing from the turbine may be cooled by a spray of water or, when acetylene is produced of a selective solvent such as acetone. Modifying agents, e.g. ethylene dibromide, or combustion promoters, e.g. ethyl nitrate or nitrite, may be introduced at any point of the system. Combustion may be stopped at a desired point by a porous flame trap coated for example with potassium chloride. Further quantities of hydrocarbon and oxygen may be fed into the turbine system at a point beyond the initial feed point; alternatively the hydrocarbon with or without oxygen may be fed into a combusted or partially combusted fuel-oxygen mixture. Combustion may take place at the interface between a stream of hydrocarbon and a parallel stream of oxygen-containing gas. The turbine parts may be cooled by "sweat cooling" as described in Specification 619,634, [Group XXVI], using, for example, the hydrocarbon to be converted as the fluid. Low pressures may be maintained in the system by connecting the outlet to an exhauster driven by a turbine, or by providing for supersonic flow between the combustion chamber and the turbine by means of specially designed ducts. Reference is also made to the formation of aromatic compounds from natural gas and oil.