GB680849A - Improvements in the purification of gases - Google Patents

Abstract

680,849. Regenerating gas-washing liquors. POWER-GAS CORPORATION Ltd. July 13, 1951, [July 13, 1950], No. 17516/50. Class 55 (ii). In the removal, from gaseous mixtures, of carbon monoxide by means of cold ammoniacal solutions of copper salts which solutions are used under pressure and are subsequently regenerated for re-use, the regeneration is effected by admitting the cold liquor at 2 to a "let-down" vessel 1 in which the pressure is reduced substantially to atmospheric pressure, released gases passing through the pipe 3 to a waste-gas scrubber 4 ; passing the liquor through pipes 5, 7 and a heater 6 to a "regenerator scrubber" 8 in which it is heated to release further gas to the scrubber 4 through a pipe 9 ; and from thence through a pipe 10 to a "reduction tank" 11 in which the excess of cupric salt is, by reaction with the carbon monoxide, still present, converted to cuprous salt before passing the liquor through a "regenerator boiler" 15 and an "oxidation tank" 17. The boiler 15 is indirectly heated to about 80‹C. with steam to drive off most of the residual carbon monoxide which, together with some steam, ammonia and carbon dioxide, passes through the pipe 28 to heat the regenerator scrubber 8 in which the steam &c. is largely reabsorbed in the cool liquor. The hot liquor passes from the boiler 15 through a pipe 16 to the "oxidation tank" 17 and is held at a high temperature for sufficient time to convert the last traces of carbon monoxide to carbon dioxide by reaction with the cupric salt still present, hot vapours passing to the scrubber 8 through the pipe 29. The hot liquor is passed by a low-pressure pump 19 through the heat-exchanger 6 and a cooler 22 to a liquid surge and conditioning tank 23 having an outlet pipe 26 leading back to the high pressure pump and the carbon monoxide absorption tower. Ammonia gas and air may be added at 24, 25. The reduction tank 11 is provided with heating-means 12, a weir 13, and a pipe 27 for leading vapours to the scrubber 8. The invention is characterized by means which, if through an excess of carbon dioxide or oxygen (air) in the original gas mixture, the carbon dioxide and oxygen content in the liquor to be regenerated is unduly high, and the reduction of the cupric salt is thus impeded, cold liquor rich in carbon monoxide is admitted directly to the reduction tank 11 and oxidation tank 17. When conditions lead to excessive reduction in the tank 11, the tank may be by-passed wholly or partly. The means comprise branch pipes, on the pipe 5, controlled by valves 30, 31 for regulating direct supply of cold liquor to the tanks 11, 17 respectively, a valve 32 for stopping, more or less, the flow to the scrubber 8, and valves 33, 34 which permit adjustable by-passing of the tank 11.