GB1443735A - Production of substitute natural gas - Google Patents

Abstract

1443735 Production of methane RALPH M PARSONS CO 24 Aug 1973 [8 Sept 1972] 40290/73 Heading C5E Substitute natural gas is produced by a process in which (i) a supply of high pressure steam from the process is used to liquefy air and prepare a stream of high pressure gaseous oxygen, (ii) an initial gas stream containing hydrogen, oxides of carbon, methane and carbon is produced by reacting a carbonaceous feed with the gaseous oxygen and steam, (iii) carbon is separated from the initial gas stream, (iv) the carbon-free gas is passed through at least one wet methanation reaction zone containing a catalyst comprising 5-35% by weight of metallic Fe, Co or Ni on an alumina and/or silica support, (v) the methanation product is cooled to produce high pressure steam, and (vi) water and any residual carbon dioxide are separated from the gas. The carbonaceous feed can be a distillation residue. Fig. 1A illustrates a process in which, following the removal of carbon, the gas is passed to water gas shift reaction and after the separation of water following the wet methanation the gas is subjected to a dry methanation in which a catalyst containing more than 30% by weight of metallic Fe, Co or Ni is used. Fig. 1B (not shown) illustrates a process similar to that of Fig. 1A but in which a portion of the carbonfree gas is passed through an initial water gas shift reactor followed by a carbon dioxide removal stage. Figs. 1C and 1D (not shown) illustrate processes corresponding to Figs. 1A and 1B except that the partial oxidation reaction is followed by a carburetion stage in which an intermediate hydrocarbon (e.g. naphtha, gasoline, kerosene or gas oil) and high-pressure steam are reacted with the gas stream to produce additional methane, hydrogen and carbon oxides. Fig. IF illustrates a process similar to that of Fig. 1D but in which a portion of the hydrogen stream from the initial water-gas shift reaction is passed into the carburetion stage.