ABSORPTION OF SO{11 {11 FROM A DILUTE GAS AND DESORPTION AT A HIGHER CONCENTRATION IN A STRIPPING GAS AT SUB-ATMOSPHERIC PRESSURE

摘要

SO2 is absorbed from a gas, such as, for example, a stack gas from a power plant burning high sulfur fuel, to form a water solution of SO2, the absorption being at a pressure approximating one atmosphere. From the water solution the SO2 is desorbed in a stripper with a fixed gas at a ratio to SO2 not 10/1. Such gases are air or a reducing gas, such as methane. Stripping is at sub-atmospheric pressures and both absorber and stripper are in multiple stages, such as two, with interconnection in which stripper and absorber are paired, stripped liquid in the first stage of the stripper being used as the absorbing liquid in the first stage of the absorber and, similarly, for the second or other stages. The paired multiple-stage absorber and stripper operation permits operating reliably with smaller amounts of stripping gas, for example, in the case of a reducing gas such as methane, without a substantial excess over that theoretically required for producing sulfur from the SO2. The reduced amounts of stripping gas permit producing higher concentrations of stripped SO2. If desired, the stripping gas can be expanded from ambient to the sub-atmospheric pressure at which it is used in expanders and can produce at least part of the power required for compressing the stripped gas back to ambient pressures.