Method for purifying amine gas sweetening systems by addition of co2

Abstract

A method for removing dissolved solids or sludge from amine absorbing solutions for acidic gas in gas sweetening systems is provided comprising contacting a stream of regenerated absorbing solution with CO 2 such that the sludge forms a precipitate and removing the precipitate from the absorbing solution. The stream of absorbing solution may then be returned to a regenerator for removal of CO 2 or returned to the gas sweetening system with the regenerated absorbing solution.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. In a gas sweetening system which acid gas is removed from gas by an acid gas absorbing solution comprising amine, a process for removing sludge, formed as a reaction product of said absorbing solution and elemental sulfur, from said absorbing solution comprising: (a) contacting a stream generated absorbing solution with CO 2  such that said sludge forms a precipitate; and   (b) removing precipitate from said stream of absorbing solution.   
     
     
       2. A process in accordance with claim 1 wherein said absorbing solution comprises a sterically hindered amine and a solvent. 
     
     
       3. A process in accordance with claim 2 wherein said absorbing solution comprises 2-piperidine ethanol and sulfolane. 
     
     
       4. A process in accordance with claim 3 wherein said absorbing solution further comprises water. 
     
     
       5. A process in accordance with claim 1 wherein said regenerated stream of absorbing solution comprises from about 0.001 to about 10 percent of said absorbing solution in said gas sweetening system. 
     
     
       6. A process in accordance with claim 1 wherein said stream of regenerated absorbing solution comprises from about 0.001 to about 1 percent of said absorbing solution in said gas sweetening system. 
     
     
       7. A process in accordance with claim 1 wherein said stream of regenerated absorbing solution is contacted with CO 2  in a gas/liquid contactor. 
     
     
       8. A process in accordance with claim 1 wherein said stream of regenerated absorbing solution is diluted with water after contacting with CO 2  to enhance removal of said precipitate. 
     
     
       9. A process in accordance with claim 1 wherein said precipitate is removed by filtration. 
     
     
       10. A process in accordance with claim 9 wherein said filtration is carried out with in-line cartridge filters. 
     
     
       11. A process in accordance with claim 1 wherein said precipitate is removed by centrifugation. 
     
     
       12. A process in accordance with claim 1 wherein said stream of absorbing solution is further returned to a regenerator for removal of CO 2 . 
     
     
       13. A process in accordance with claim 1 wherein said stream of absorbing solution is further returned to said gas sweetening system with the regenerated absorbing solution. 
     
     
       14. In a gas sweetening system wherein CO 2  and H 2  S are removed from gas by an absorbing solution comprising a sterically hindered amine and a solvent, a process for removing sludge from said absorbing solution comprising: (a) contacting a stream of regenerated absorbing solution, wherein said stream comprises from about 0.001 to about 10 percent of said absorbing solution in said gas sweetening system, with CO 2  such that said sludge forms a precipitate; and   (b) removing said precipitate from said stream of absorbing solution.   
     
     
       15. In a gas sweetening system wherein CO 2  and H 2  S are removed from gas by an amine absorbing solution comprising 2-piperidine ethanol, sulfolane and water, a process for removing sludge from said absorbing solution comprising: (a) contacting a stream of regenerated absorbing solution, wherein said stream comprises from about 0.001 to about 1 percent of said absorbing solution in said gas sweetening system, with CO 2  such that said sludge forms a precipitate;   (b) diluting said stream of absorbing solution with water; and   (c) removing said precipitate from said stream of absorbing solution by filtration.