GB1063517A - Methods and composition for the purification of gases - Google Patents

Abstract

A composition suitable for removing CO2 and H2S from a gas mixture, comprises an aqueous solution of a major proportion of potassium carbonate or borate or a mixture thereof activated by a minor proportion of ethylene polyamines, alkanolamines, alkanolamine borates or mixtures thereof. Gas mixture containing CO2 and H2S enters absorber 1 at 7 and passes up packed absorption zone 3 against a lean aqueous potassium carbonate solution entering by line 11, through chimney tray 8 to packed absorption zone 4 against a lean aqueous monoethanolamine (MEA) solution entering by line 18 and leaves the absorber at 9. Rich K2CO3 solution leaves the absorber by line 12 passing to regenerator 2 where it is contacted with steam in zone 6 and collects above chimney tray 14 being returned to absorber 1 by way of pump 10. Rich MEA solution is withdrawn from absorber 1 at 8 by line 19, passing through exchanger 20 to regeneration zone 5 where it is contacted with steam before being returned to the absorber by way of heat exchanger 20, pump 16 and cooler 17. The steam for regeneration which may be either introduced at the bottom of regenerator 2 or made by boiling the aqueous amine solution at 23, leaves the regenerator by <PICT:1063517/C1/1> line 25 together with CO2 and any H2S present and is condensed at 26 any MEA present in the condensate being returned to regenerator 2 by line 29. An alkali metal vanadate, vanadite or arsenite may be added to the solution as a corrosion inhibitor. Tetra-ethylenepentamine is used in one example whilst a list of suitable amines is given. It is stated to be known to use As2O3, selenons or tellurons acids, protides and amino acids as activators for potassium carbonate scrubbing solutions.