Patent GB-232986-A (GB)
Title: Improved process for the separation of the several components of a gaseous mixture of any kind
IPC: F25J3/04
Filed: 1925-04-27
Abstract: 232,986. Patart, G. L. E. April 26, 1924, [Convention date]. Separating gaseous mixtures by liquefaction.-Rectifying columns used for the separation of constituents of a gaseous mixture, for example a mixture containing hydrogen and hydrocarbons &c., are combined with a rectifying column in which liquid nitrogen is obtained from air on the upper plates by a condenser, the liquid nitrogen being used as the rectifying liquid for the mixtures under treatment. The gas under treatment, for example coal gas purified and in some cases hydrogenated by catalysis, is compressed, cooled in a heat exchanger 3, and passed through a rectifying column 6 fitted with a condenser 7, from the top of which a mixture of hydrogen and nitrogen issues through a pipe 8, and the heat exchanger 3. The liquid nitrogen is supplied to the column at the point 12 by a valved siphon tube from air rectification column 25. Air for this column is compressed by a compressor 16, water cooled, and further cooled in heat exchangers 18-20 traversed by the separated nitrogen, oxygen and argon, and passed through valves to a common supply pipe 23 for the column, which is fitted with superposed condensers 26, 27, and from one of the upper plates of which liquid nitrogen is withdrawn for the column 6. An outlet 28 above the condensers allows the escape of helium and other uncondensed gases, including some nitrogen which may be added to the mixture discharged from the column 6. The cooling of the upper part of the column 25 is effected by a methane refrigerating apparatus. Methan is withdrawn from a tank 31 by a compressor 32, and after water cooling in a cooler 33 flows in part through a heat exchanger 34 cooled by methane and by evaporating liquid ethylene obtained from a previous cycle. The inflowing methane is completely liquefied, and is expanded thrugh a valve 35 and passes into the lower condenser 26 of the air column. The vaporized methane from the condenser passes out through the pipe 37 and through the first and last sections of the exchanger 34 back to the compressor inlet; the intermediate section of the exchanger 34 is cooled by ethylene. The liquids forming in the column 6 are discharged through a valve 40 into a double rectifying column 42, 47. Entering the upper section, they are evaporated by tubes with closed ends heated by the gases in the lower section; nitrogen passes away through the condenser 63, liquid carbon monoxide flows down from the upper plates, and the methane and ethylene pass through a pipe 44 into the lower section, where they are rectified. The nitrogen and carbon monoxide return through a pipe 48 into the upper section; methane is discharged from the upper plates; and ethylene collecting at the bottom is discharged through a pipe 56 into the cooling device 118 of the ethylene refrigerating circuit, comprising a tank 115, compressor 116, cooler, and heat exchanger, by which the methane is liquefied. The escaping carbon monoxide is expanded through a valve 59, cools compressed methane in an exchanger 60, and passes off through a valve 62, whence it may be returned to be hydrogenated or be used for combustion. That part of the methane in the water cooler 33 which is not used in the condenser 26 passes through a pipe 97 from which branch pipes are led to heat the bottoms of the rectifying columns; these branch pipes are connected with a return pipe 98 to which the remainder of the methane is also conveyed after passing through the carbon monoxide exchanger 60. An ammonia circuit, comprising a compressor 125, cooler 126, tank 123, and expansion valve 127, liquefies the ethylene. Liquid rich in argon is withdrawn from the column 25 through a pipe 83 into a rectifying column 84 from which nitrogen passes off through the condenser 76, argon is withdrawn in the liquid state at the point 85, and oxygen is withdrawn at the bottom. Liquid nitrogen is withdrawn under pressure from the column 25 at the point 66, and is passed through the condensers 7, 63, 76, finally passing off through a pipe 80 to the heat exchanger 18 for the air to be liquefied and to an outlet valve 96.