GB391532A - Process and apparatus for the thermal decomposition of hydrocarbons - Google Patents

Abstract

In a process for the thermal decomposition of methane or a gas containing it by passage through heated refractory material, whereby carbon, hydrogen and small amounts of hydrocarbons other than methane are produced, the heat of the cracked products is utilized by injecting into the gas stream at one or more points further quantities of the gas to be treated. In the apparatus shown, a vertical <PICT:0391532/III/1> converter 1 filled with refractory material is heated by burners 2 supplied with hydrocarbon fuel by a valved pipe 3 and with air from a blower 7 by a manifold 6. Leading from a lower part of the converter is a stack pipe 8 provided with a valve 9, and from the valved top of the converter is a pipe 17 through which the cracked products are withdrawn. Steam and hydrocarbons are admitted to the stack pipe by valved pipes 10, 12 respectively. Valved pipes 15, 23, 24 are provided to admit further supplies of hydrocarbons to the top of the converter and to the pipe 17. The lower end of the pipe 17 is closed, a pipe 27 leading therefrom into a wash box 20 where the carbon produced is trapped, the gaseous products leaving by a pipe 21. In operation, the valve 14 being closed and the stack valve 9 open, the refractory material is heated by combustion of the hydrocarbons from the pipe 3, the hot gases passing downwards through the converter and up the stack pipe. When the desired temperature is attained, the valve 9 is closed and the hydrocarbon gas to be cracked is injected into the stack by the pipe 12, cracking commencing in the stack and being completed in the converter. Further gas to be cracked by the hot reaction gases may be injected by the pipes 15, 23, 24. After the temperature of the converter has reached the lower limit, the supply of material is cut off, the valve 14 opened and the contents of the converter removed by steam injected by the pipe 10, after which the converter is reheated. An example is given of the treatment of natural gas containing principally methane and ethane in the proportion of 83 to 17; the refractory material is heated to 1100 DEG C. and the gas resulting therefrom contains small amounts of acetylene, ethylene, carbon dioxide and nitrogen, together with 11,6 per cent of carbon monoxide, 72,7 of hydrogen and 12,7 of methane. After treatment with supplementary gas, the main gaseous content is 10 per cent of carbon monoxide, 67,4 of hydrogen and 18,1 of methane.