Abstract: A method of controlling temperature during a pyrolysis reaction wherein the predominant pyrolysis reactions are endothermic. A fuel and oxidizer are combusted in a combustion zone to produce a hot gas stream at a superatmospheric pressure. The hot gas stream is then passed through a converging-diverging nozzle to accelerate the hot gas stream to a velocity of at least about mach 2. The reactant to be pyrolyzed is injected into the supersonic hot gas stream to produce a reaction mixture flowing at supersonic velocity and initiate the endothermic pyrolysis reactions. Substantially immediately thereafter the velocity of the reaction mixture is reduced over a predetermined reaction time to convert the kinetic energy of the reaction mixture to thermal energy in an amount sufficient to substantially offset the endothermic reactions taking place while maintaining supersonic flow. At the end of the predetermined reaction time the velocity of the reaction mixture is reduced to subsonic flow and the reaction quenched.

Abstract: A process wherein coal is reacted with a hot gas stream to produce acetylene. The process comprises the sequential steps of reacting a fuel, oxygen and steam under controlled conditions of temperature to produce a hot gas stream principally comprising hydrogen, carbon monoxide and steam along with minor amounts of carbon dioxide, and essentially free of O, OH and O.sub.2. The hot gas stream is accelerated to a high velocity and impinged upon a stream of particulate bituminous or subbituminous coal and thereafter the mixture of hot gas and coal is decelerated to a velocity of from about 150 to 300 feet per second. The amounts of the streams of particulate coal and hot gas are controlled to produce in the reaction zone a pressure in the range of from about 10 to 100 psia and a temperature of from about 1800.degree. to 3000.degree. F.