Self-Concentrating Absorbent for Acid Gas Separation

Abstract

A process and systems for efficiently deacidizing a gaseous mixture is described. The process and systems utilize a self-concentrating absorbent that absorbs an acid gas at reduced overall energy costs for the deacidizing operation.

1 . A system for deacidizing a gaseous mixture comprising an acid gas, comprising:
 an absorption unit adapted to allow contact between the gaseous mixture and an absorbent comprising an amine dissolved in a solvent at a first concentration, wherein the absorbent absorbs the acid gas to form a concentrated-amine phase, wherein the concentrated-amine phase is mechanically separable from the remaining of the absorbent, and the concentrated-amine phase comprises a concentrated amine at a concentration higher than the first concentration and an absorbed acid gas, wherein the concentrated amine comprises the amine or the amine having a chemical modification, and the absorbed acid gas comprises the acid gas or the acid gas having a chemical modification   a separation unit adapted to allow separation of the concentrated-amine phase from the remaining of the absorbent; and   a regeneration unit adapted to allow regeneration of the concentrated-amine phase, so as to obtain the acid gas and the concentrated amine.   
     
     
         2 . The system of  claim 1 , wherein the separation unit is placed in a position lower than the absorption unit, so that after the absorbent absorbs the acid gas to form a gas-rich absorbent, the gas-rich absorbent moves downward from the absorption unit to the separation unit by gravity. 
     
     
         3 . The system of  claim 2 , wherein the absorption unit, the separation unit and the regeneration unit are placed in a single tower, wherein the separation unit is placed in a position lower than the absorption unit and the regeneration unit is placed in a position lower than the separation unit, so that after the absorbent absorbs the acid gas, the gas-rich absorbent moves downward from the absorption unit to the separation unit by gravity, and after the step of separation, the concentrated-amine phase moves downward from the separation unit to the regeneration unit by gravity. 
     
     
         4 . The system of  claim 1 , wherein the regeneration unit is placed in a position lower than the separation unit, so that after the step of separation, the concentrated-amine phase moves downward from the separation unit to the regeneration unit by gravity. 
     
     
         5 . A system for deacidizing a gaseous mixture comprising an acid gas, comprising:
 an absorption unit adapted to allow contact between the gaseous mixture and an absorbent comprising an agent dissolved in a solvent at a first concentration,
 wherein the agent is selected from the group consisting of amino-acid salts, amides, alkaline salts, alkaline-earth salts, ammonium salts, ureas, alkaline metal phosphates, carbonates, borates, acid phosphites, phosphites, phosphonite, phosphinate, phosphonate, acid phosphates, pyrophosphites, bicarbonates, metaborates, diborates, tetraborates, pentaborates, and combinations thereof; 
 wherein the absorbent absorbs the acid gas to form a concentrated-agent phase, the concentrated-agent phase is mechanically separable from the remaining of the absorbent, and the concentrated-agent phase comprises a concentrated agent at a concentration higher than the first concentration and an absorbed acid gas, 
 wherein the concentrated agent comprises the agent or the agent having a chemical modification, and the absorbed acid gas comprises the acid gas or the acid gas having a chemical modification; 
   a separation unit adapted to allow separation of the concentrated-agent phase from the remaining of the absorbent; and   a regeneration unit adapted to allow regeneration of the concentrated-agent phase, so as to obtain the acid gas and the concentrated agent.   
     
     
         6 . The system of  claim 5 , wherein the solvent comprises water, an aqueous solution containing one or more salts selected from alkaline salts, ammonium salts, alkanolamine salts, alkaline-earth salts, phosphates, acid phosphites, phosphites, phosphonite, phosphinate, phosphonate, acid phosphates, pyrophosphites, carbonates, bicarbonates, borates, metaborates, diborates, tetraborates, or pentaborates.