GB420506A - Method of and means for obtaining inorganic acid gases from gaseous mixtures - Google Patents

Abstract

<PICT:0420506/III/1> Inorganic acid gases, such as carbon dioxide, sulphur dioxide and sulphuretted hydrogen, are separated from gaseous mixtures by absorption in a substantially anhydrous undiluted difficulty volatilizable organic amine (other than a pure aromatic amine or a heterocyclic amine possessing similar properties), the acid gas being subsequently driven off with the aid of a vapour of an organic solvent which is insoluble in water and which forms with water an azeotropic heterogeneous vapour mixture. Suitable amines include the amino-alcohols such as mono-, di-, or tri-ethanolamine, mono-propanolamine (aminoisopropyl alcohol) or phenylethanalamine, their homologues such as ethyl diethanolamine and the morpholine bases obtained from multiamine alcohols by dehydration, such as oxyethylmorpholine and its homologues. The organic solvents referred to are benzol and its homologues, benzene, and halogenized hydrocarbons such as carbon tetrachloride and chloroform alone or in admixture; a mixture of benzol and carbon tetrachloride is particularly referred to. The vapour of the organic solvent removes from the amine base any water it absorbs from the treated gases, in addition to the acidic gases. A carbon dioxide containing gas enters an absorption tower 1 through a port 2 and passes up the tower in counter current to a stream of anhydrous amine alcohol, the carbon dioxide free gas passing away through a pipe 4. The base, containing carbon dioxide, is pumped by a pump 7 through a preheater 8 into an extracting column 10 at a temperature of about 60 DEG C. The base descends the column in counter current to benzol vapour entering p through a pipe 12, is heated by a coil 15 to 140 DEG C. to remove traces of benzol and is pumped by a pump 16 through the preheater 8 and a cooler 17 to re-enter the tower 1 via a pipe 3. The benzol vapour containing carbon dioxide and water vapour passes through a pipe 13 to a cooler 14 which condenses the benzol and water. This liquid mixture passes to a separator 18 while the pure carbon dioxide flows away through a pipe 22. The layer of benzol passes from the separator through a pipe 20 to an evaporator 21 for the production of further benzol vapour for the tower 10. The towers 1 and 10 may contain either column apparatus or coke or like fillings. Specification 344,786 is referred to.