Process for removing hydrogen sulphide from industrial gases

摘要

The invention relates to a process for removing the hydrogen sulphide from industrial gases having a low oxygen content, in particular having an oxygen content less than 0.1%. The hydrogen sulphide-containing gas is introduced into a scrubbing tower and is there scrubbed by a Stretford scrubbing liquid containing one or more anthraquinone acids and/or salts thereof. The clean gas is conducted out of the scrubbing tower, the Stretford scrubbing liquid is taken off from a scrubbing tower delay tank and fed to an oxidiser. Air is blown into the oxidiser and sulphur is withdrawn from the oxidiser by flotation and fed to sulphur processing, while the Stretford scrubbing liquid is pumped back to the scrubbing tower. In the Stretford scrubbing liquid, thiosulphate is formed during the scrubbing process. In order that interfering losses of the anthraquinone compounds used do not occur and further that thiosulphate destruction is not necessary in the waste water treatment, hydrogen sulphide ions are introduced into the oxidiser from the scrubbing tower. As a result, a thiosulphate level of over 15 grams per litre, preferably in the range from 20 to 200 grams per litre, is maintained in the Stretford scrubbing liquid. Surprisingly, interfering losses of the anthraquinone salt used or of the anthraquinone salts used are avoided in this manner.