Methods and system for separating carbon dioxide from syngas

Abstract

A system for use in separating carbon dioxide and acid gas from syngas includes a syngas purification circuit that includes at least one adsorption tower coupled in flow communication to a supply of lean solvent. The system further includes a carbon dioxide removal circuit coupled downstream from the syngas purification circuit. The carbon dioxide removal circuit includes at least one component that facilitates the removal of carbon dioxide from the solvent after the solvent has passed through the syngas purification circuit. The carbon dioxide removal circuit also includes at least one compressor, wherein the at least one component and the at least one compressor are operable at substantially similar pressures. In addition, the system includes an acid gas removal circuit that is coupled downstream from the carbon dioxide removal circuit. The acid gas removal circuit includes at least one adsorption tower.

1 . A system for use in separating carbon dioxide and acid gas from syngas comprising:
 a syngas purification circuit comprising at least one adsorption tower coupled in flow communication to a supply of lean solvent;   a carbon dioxide removal circuit coupled downstream from said syngas purification circuit, said carbon dioxide removal circuit comprising at least one component that facilitates the removal of carbon dioxide from the solvent after the solvent has passed through said syngas purification circuit and at least one compressor, wherein the at least one component and the at least one compressor are operable at substantially similar pressures; and   an acid gas removal circuit coupled downstream from said carbon dioxide removal circuit, said acid gas removal circuit comprising at least one adsorption tower.   
     
     
         2 . A system in accordance with  claim 1 , wherein said carbon dioxide removal circuit further comprises a compressor circuit, a rich solvent circuit, and a semi-rich solvent circuit. 
     
     
         3 . A system in accordance with  claim 2 , wherein said compressor circuit comprises a first compressor unit, a second compressor unit, and a third compressor unit coupled together in a serial flow arrangement. 
     
     
         4 . A system in accordance with  claim 3 , wherein said semi-rich solvent circuit comprises a first flash unit, a second flash unit, and a third flash unit coupled together in a serial flow arrangement. 
     
     
         5 . A system in accordance with  claim 4 , wherein said first compressor unit and said first flash unit are operable at substantially similar pressures, said second compressor unit and said second flash unit are operable at substantially similar pressures, and said third compressor unit and said third flash unit are operable at substantially similar pressures. 
     
     
         6 . A system in accordance with  claim 5 , wherein said semi-rich solvent circuit further comprises a heat exchanger configured to:
 increase a temperature of solvent exiting said semi-rich solvent circuit; and to decrease a temperature of solvent channeled from said solvent stripper circuit to said syngas purification circuit.   
     
     
         7 . A system in accordance with  claim 3 , wherein said rich solvent circuit comprises a first flash unit and a second flash unit, wherein said first flash unit and said first compressor unit are operable at substantially similar pressures, and wherein said second flash unit and said second compressor unit are operable at substantially similar pressures. 
     
     
         8 . A system in accordance with  claim 2 , wherein said syngas purification circuit comprises an acid gas absorption tower configured to remove acid gas and carbon dioxide from syngas. 
     
     
         9 . A system in accordance with  claim 8 , wherein said semi-rich solvent circuit comprises a return pump that facilitates supplying lean solvent from said acid gas removal circuit to said acid gas absorption tower. 
     
     
         10 . A system in accordance with  claim 9 , wherein said syngas purification system further comprises a solvent cooler coupled upstream from said acid gas absorption tower, said solvent cooler is configured to reduce a temperature of solvent supplied to said acid gas absorption tower. 
     
     
         11 . A system in accordance with  claim 10 , wherein said solvent cooler facilitates reducing the solvent to a temperature of from about 0° C. to about 100° C. 
     
     
         12 . A system in accordance with  claim 2 , wherein said syngas purification circuit at least one adsorption column comprises a first acid gas absorption tower and a second acid gas absorption tower, said first and second acid gas absorption towers are configured to remove acid gas and carbon dioxide from syngas. 
     
     
         13 . A system in accordance with  claim 12 , wherein said semi-rich solvent circuit comprises a return pump that supplies lean solvent from said acid gas removal circuit to said second acid gas absorption tower. 
     
     
         14 . A system in accordance with  claim 13 , wherein said syngas purification system further comprises a solvent cooler coupled upstream from said second acid gas absorption tower, said solvent cooler configured to reduce a temperature of solvent supplied to said second acid gas absorption tower. 
     
     
         15 . A system in accordance with  claim 14 , wherein said solvent cooler facilitates reducing the solvent to a temperature of from about 0° C. to about 100° C. 
     
     
         16 . A system in accordance with  claim 15 , wherein said syngas purification circuit further comprises a solvent return pump configured to channel the solvent from said second acid gas absorption tower to said first acid gas absorption tower. 
     
     
         17 . A system for use in separating carbon dioxide and acid gas from syngas comprising:
 at least one acid gas absorption tower coupled in flow communication with a supply of lean solvent, said at least one acid gas absorption tower configured to produce a purified stream of syngas;   a solvent circuit coupled downstream from and in flow communication with said at least one acid gas absorption tower, said solvent circuit comprises at least one component that facilitates removing carbon dioxide from the solvent, wherein said at least one component is operable at a first pressure;   a compressor circuit coupled in flow communication with said solvent circuit, said compressor circuit comprises at least one compressor that is operable at a second pressure, wherein the first pressure and second pressure are substantially similar; and   an acid gas removal solvent stripper coupled in flow communication with said solvent circuit and said at least one acid gas absorption tower.   
     
     
         18 . A system in accordance with  claim 17  further comprising a lean solvent cooler coupled upstream from said at least one acid gas absorption tower, said cooler facilitates reducing a temperature of the supply of lean solvent entering said at least one acid gas absorption tower. 
     
     
         19 . A method of assembling a syngas purification system comprising:
 providing at least one acid gas absorption tower;   coupling a lean solvent supply line to the at least one acid gas absorption tower;   coupling a syngas supply line to the at least one acid gas absorption tower, wherein the at least one acid gas absorption tower is configured to produce a purified stream of syngas;   coupling at least one flash unit downstream from said acid gas absorption tower, wherein the at least one flash unit is operable at a first pressure to produce a stream of carbon dioxide;   coupling at least one compressor unit downstream from the at least one flash unit, wherein the at least one compressor unit is operable at a second temperature that is substantially similar to the first pressure; and   coupling an acid gas removal solvent stripper downstream from the at least one flash unit, wherein the acid gas removal solvent stripper is configured to produce a stream of acid gas.   
     
     
         20 . A method in accordance with  claim 19  further comprising coupling a second acid gas absorption tower in flow communication with the first acid gas absorption tower, wherein the second acid gas absorption tower facilitates removing of carbon dioxide and acid gas from a supply of syngas channeled through the syngas supply line.