GB728444A - Improvements in or relating to drying or purifying natural gases or waste gases fromhydrogenating or cracking processes - Google Patents

Abstract

728,444. Purifying gas. GES. FœR LINDE'S EISMASCHINEN AKT.-GES., and LURGI GES. FœR WARMETECHNIK. Dec. 10, 1951 [Dec. 9, 1950], No. 28922/51. Class 55 (2). [Also in Group XIII] Impurities such as hydrogen sulphide, mercaptans carbon dioxide, water vapour and resin formers are removed, together with C 2 - to C 5 - hydrocarbons, from natural gas and the like by cooling the gas under pressure to below 0‹ C., whilst washing it with polar washing agents, preferably methanol, to remove the hydrogen sulphide. &c., and with non-polar washing agents such as C 3 - to C 7 - hydrocarbons to remove the C 2- to C 5 - hydrocarbons. In one form, the process consists in cooling the gas to minus 40‹ C: in contact with a polar solvent such as acetal or the lower ketones or ethers or with aldehydes, aliphatic or aromatic monohydric or polyhydric alcohols, the lower esters of formic and like acids, amines amino alcohols and nitriles and the corresponding aromatic compounds or substances containing aromatic -OH groups, the solvent absorbing the H 2 S &c. and with non-polar solvents such as C 5 - to C 7 - hydrocarbons which dissolve the C 2 - to C 5 - hydrocarbons contained in the gas. To regenerate the' washing agent, it is first separated into its polar and non-polar constituents by stratification and the dissolved gases freed by controlled evaporation, for example as described in Specification 692,804. The gas may be cooled by direct heat exchange with intensively cooled washing agent to which 10 to 50 per cent of water is added when it is desired to prevent absorption of any methane or ethane.