GB1448562A - Process for the production of methane containing gases - Google Patents

Abstract

1448562 High methane content gas BRITISH GAS CORP 5 Dec 1973 [18 Dec 1972] 58368/72 Heading C5E A gas containing a high proportion, e.g. more than 85% by volume calculated on a dry CO 2 -free basis, of methane is produced by (i) producing a gas containing a substantial proportion of methane by the low temperature catalytic gasification, in a first catalytic reaction zone of a mixture of steam and the vapour of a predominantly paraffinic hydrocarbon feedstock having a final boiling point of not more than 350‹ C.; (ii) increasing the proportion of hydrogen in the gas mixture produced in stage (i) by passing at least a part of the gas mixture into a second catalytic reforming zone in which the mixture reacts in the presence of a steam reforming catalyst to convert a proportion of the methane contained therein to hydrogen and carbon oxides; (iii) mixing the gas mixture produced in stage (ii) with a further supply of predominantly paraffinic hydrocarbon feedstock and, optionally, steam; and (iv) passing the mixture formed in stage (iii) into a third catalytic hydrogasification zone wherein the constitutents of the mixture react to increase the proportion of methane in the mixture. The catalytic reactions may be carried out at 5 to above 100 atmospheres, e.g. at the transmission pressure of the final gas. The catalyst beds may be static or fluidized beds. The feedstock and steam for the first zone may be preheated to between 400‹ and 500‹ C. 5 to 10% by wt. of the total feedstock supplied to the first and third catalytic stages may be employed for the first stage reactor and all the first stage offgases is subjected to reforming in the second stage with additional steam being supplied prior to the second stage reforming reaction; or 15 to 35% by wt. of the total feedstock supplied to the first and third catalytic stages may be employed for the first stage reaction and only a part of the first stage off-gases is subjected to reforming, the non-reformed part being subjected to the third stage reaction, in admixture with the reformed part, fresh steam and the remainder of the feedstock. The inlet temperature of the gas mixture to the third stage reactor may be from 300‹ to 400‹ C. and the outlet end of the third stage reactor may be cooled to between 200‹ to 250‹ C. The gases from the third stage reactor may be subjected to methanation. The methane-containing product gas may be subjected to carbon dioxide removal.