Improvements in or relating to purifying gases by treatment with copper ammonia solutions

摘要

Spent ammoniacal cuprous solutions, obtained in purifying gas mixtures containing hydrogen from carbon dioxide, carbon monoxide and oxygen, are regenerated by subjecting them to a preliminary heating under pressure, e.g. at temperatures of 40--70 DEG C. and then to a further heating at atmospheric pressure, and at a higher temperature to expel the absorbed carbon oxides, the time of heating in the first step being such that the reducing effect of the carbon monoxide compensates for the oxidizing effect of the oxygen and returns the ratio of cuprous to cupric copper in the solution to its original predetermined value. The ratio of cuprous to cupric copper after regeneration is preferably 14 : 2 by weight. Gases prepared by the catalytic reaction of water gas with steam and containing nitrogen, hydrogen, carbon monoxide and carbon dioxide enter a scrubber 10 by a conduit 12 where scrubbing with water under pressure removes most of the carbon dioxide but introduces a small amount of oxygen. The resulting gas leaving the scrubber by a pipe 22 is further compressed by a device 24 and is scrubbed in a tower 26 by a cold ammoniacal cuprous solution, the purified gas leaving through a conduit 31. The spent solution leaves through a valve 34 and is discharged into one or other of identical tanks 36, 38 heated by steam coils. The solution remains for the time necessary for effecting the reduction. The pressure is controlled by means of valves 111 in the conduits 109, while, if necessary, additional carbon monoxide may be supplied by means of the conduits 110. After reduction the solution passes through conduits 50 and 70, down a tower 72 and through steam heated tubes 78. During the rapid passage of the solution through the tower 72 and tubes 78, carbon monoxide and dioxide are driven off and pass away through the exit 73 and ammonia they contain being re-absorbed by the cooler solution at the top of the tower. The tubes 78 may be heated to 70--80 DEG C. The regenerated solution passing away through a conduit 90 is cooled in a cooler 92 and pumped by a pump 98, if desired through a further cooler 102, to the top of the tower 26 for re-use. If desired a portion of the spent solution may byepass the vessels 36, 38 by means of a conduit 52, that portion passing into the vessels being subjected to a relatively strong deoxidation.