Process for removal of sour gases by scrubbing
AssigneeLinde Aktiengesellschaft
InventorsKarl Baur, Eberhard Lassmann, Heinz Karwat
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Abstract
In the removal of sour gases by scrubbing with an aqueous alkali metal salt solution, e.g. a solution of K.sub.2 CO.sub.3, the circulating scrubbing liquid is gradually contaminated with organic acids, especially formic acid, which in turn ties up K.sup.+ as the formate which is ineffective for scrubbing purposes. To remove the organic acids, at least a partial stream of the circulating scrubbing liquid is subjected to an oxidation step under conditions leading to the oxidation of the salts of the organic acids, thereby liberating the bound alkali metal ions. If the scrubbing liquid contains an oxidizable activator, the latter can be extracted prior to oxidation of the scrubbing liquid and added back subsequent to the oxidation.
Claims18
In a continuous process for removing sour gas comprising H.sub.2 S and/or CO.sub.2 from a gaseous mixture, which process comprises scrubbing the gaseous mixture with an aqueous solution comprising a salt of an alkali metal and a weak inorganic acid as the scrubbing liquid;
- subjecting resultant loaded scrubbing liquid to regeneration by pressure reduction;
- and recycling regenerated scrubbing liquid to the scrubbing stage, the improvement wherein carboxylic acids are introduced with the gaseous mixture in trace amounts and/or are formed during the scrubbing stage, and form salts with alkali metal cations in the scrubbing liquid, and which comprises subjecting a continuous partial stream of the scrubbing liquid to an oxidation step under conditions sufficient to liberate alkali metal cations from the salts of said carboxylic acids contained in the scrubbing liquid to reconstitute the scrubbing liquid with said salt of an alkali metal and a weak inorganic acid.
In a process for removing CO.sub.2 from a gaseous mixture comprising CO and CO.sub.2, which process comprises scrubbing the gaseous mixture with an aqueous solution of potassium carbonate and an activator to improve the absorption capacity of the aqueous solution, said activator being oxidizable;
- subjecting resultant loaded scrubbing liquid to regeneration;
- and recycling regenerated scrubbing liquid to the scrubbing stage, the improvement comprising subjecting at least a partial stream of the scrubbing liquid containing a potassium salt of formic acid, the latter being formed by the reaction of CO and H.sub.2 O in the scrubbing stage, to an oxidation step under conditions sufficient to liberate the potassium cation from the potassium salt of formic acid in order to reconstitute the scrubbing liquid with potassium carbonate.
Dependencies are inferred from the claim text.