Configurations and methods for gasification plants

Abstract

A syngas treatment plant has a decarbonization section and a desulfurization section that use the same solvent to remove various acid gases. Contemplated methods and plants are highly effective in removal of CO2, recycle sulfurous contaminants to extinction. Minimal loss of H2 while maximizing H2S concentration in a Claus plant feed during regeneration of the solvent is achieved by stripping the solvent with both treated syngas and a flash vapor of the desulfurization section.

What is claimed is: 
     
         1 . A method of operating a syngas treatment plant, comprising:
 providing a syngas and a CO2-loaded lean solvent from a CO2 absorber to an H2S absorber to so produce in the H2S absorber a CO2-loaded rich solvent and a desulfurized syngas;   stripping CO2 and H2 from the CO2-loaded rich solvent in a first stripper using a treated syngas as a first stripping gas and using a flash vapor as a second stripping gas to thereby produce a stripped rich solvent and a CO2/H2-rich recycle gas;   flashing the stripped rich solvent to thereby produce the flash vapor;   further stripping the stripped rich solvent in a second stripper to thereby regenerate a lean solvent for use in the CO2 absorber and to thereby produce a concentrated acid gas; and   feeding the desulfurized syngas into the CO2 absorber to thereby produce the treated syngas and the CO2-loaded rich solvent.   
     
     
         2 . The method of  claim 1  further comprising a step regenerating a portion of the CO2-loaded lean solvent in a plurality of flash steps, and using refrigeration content from the flash steps for refrigeration in the CO2 absorber. 
     
     
         3 . The method of  claim 2  wherein at least one of the plurality of flash steps produces a flash gas, further comprising a step of recycling the flash gas to the CO2 absorber. 
     
     
         4 . The method of  claim 1  further comprising a step of feeding the concentrated acid gas into a Claus plant and combining a Claus plant tail gas after hydrogenation with the syngas. 
     
     
         5 . The method of  claim 1  further comprising a step of separating water from the CO2/H2-rich recycle gas and feeding the water to the second stripper as a reflux stream. 
     
     
         6 . The method of  claim 1  further comprising a step of hydrolyzing COS in the CO2/H2-rich recycle gas using a COS hydrolysis reactor. 
     
     
         7 . The method of  claim 1  wherein the syngas is a shifted syngas. 
     
     
         8 . The method of  claim 1  wherein the CO2/H2-rich recycle gas is recycled to the H2S absorber. 
     
     
         9 . A method of operating a syngas treatment plant comprising a decarbonization section and a desulfurization section, the method comprising:
 regenerating a portion of a CO2-loaded lean solvent in the decarbonization section in a plurality of flash steps and using refrigeration content from the flash steps for refrigeration of a CO2 absorber while absorbing CO2 from a desulfurized gas in the CO2 absorber to thereby produce a treated syngas and a CO2-loaded lean solvent from a lean solvent;   providing a syngas and the CO2-loaded lean solvent from the decarbonization section to an H2S absorber in the desulfurization section to thereby produce a CO2-loaded rich solvent and the desulfurized gas;   stripping CO2 and COS from the CO2-loaded rich solvent in a first stripper using a treated feed gas as a first stripping gas to thereby produce a stripped rich solvent and a CO2/COS-containing overhead product;   feeding the CO2/COS-containing overhead product into a COS hydrolysis reactor to hydrolyze COS and produce a recycle gas for combination with the syngas; and   further stripping the stripped rich solvent in a second stripper to thereby regenerate the lean solvent and to thereby produce a concentrated acid gas.   
     
     
         10 . The method of  claim 9  further comprising a step of subjecting the syngas to a shift reaction prior to providing the syngas to the H2S absorber. 
     
     
         11 . The method of  claim 9  further comprising a step of combining the recycle gas with the syngas. 
     
     
         12 . The method of  claim 9  further comprising a step of feeding the concentrated acid gas into a Claus plant and combining a Claus plant tail gas after hydrogenation with the syngas. 
     
     
         13 . The method of  claim 9  wherein the concentrated acid gas has an H2S content of at least 35 mol % and wherein the treated syngas has a CO2 content of equal or less than 2 mol %. 
     
     
         14 . A syngas treatment plant, comprising:
 an H2S absorber that is configured to receive a syngas and a CO2-loaded lean solvent and that is further configured to produce a CO2-loaded rich solvent and a desulfurized syngas;   a first stripper fluidly coupled to the H2S absorber to receive the CO2-loaded rich solvent and configured to allow use of a treated syngas as a first stripping gas and of a flash vapor as a second stripping gas to thereby allow production of a stripped rich solvent and a CO2/H2-rich recycle gas;   a first flash vessel fluidly coupled to the first stripper and configured to receive and flash the stripped rich solvent to thereby allow production of the flash vapor;   a second stripper fluidly coupled to the first flash vessel and configured to receive and further strip the stripped rich solvent to thereby allow generation of a lean solvent and a concentrated acid gas; and   a CO2 absorber fluidly coupled to the H2S absorber and configured to receive the desulfurized syngas, and further configured to allow production of the treated syngas from the desulfurized syngas with use of the lean solvent to thereby allow production of the CO2-loaded rich solvent.   
     
     
         15 . The syngas treatment plant of  claim 14  further comprising a plurality of flash drums coupled to the CO2 absorber and configured to allow regeneration of a portion of the CO2-loaded lean solvent in a plurality of flash steps, and a heat exchanger coupled to the CO2 absorber and configured to allow use of refrigeration content from the portion of the CO2-loaded lean solvent for refrigeration in the CO2 absorber. 
     
     
         16 . The syngas treatment plant of  claim 15  wherein at least one of the plurality of flash drums is configured to allow production of a flash gas, and a conduit that fluidly couples the at least one of the plurality of flash drums to the CO2 absorber to so allow for recycling of the flash gas to the CO2 absorber. 
     
     
         17 . The syngas treatment plant of  claim 14  further comprising a shift reactor fluidly coupled to the H2S absorber and configured to provide shifted syngas to the H2S absorber. 
     
     
         18 . The syngas treatment plant of  claim 14  further comprising a Claus plant and a Claus plant tail gas unit configured to receive the concentrated acid gas and to produce a treated tail gas, and further comprising a conduit that allow combination of the treated tail gas with the syngas. 
     
     
         19 . The syngas treatment plant of  claim 14  further comprising separator fluidly coupled to the first stripper and configured to allow separation of water from the CO2/H2-rich recycle gas, and further comprising a conduit that is configured to allow feeding of the water to the second stripper as a reflux stream. 
     
     
         20 . The syngas treatment plant of  claim 14  further comprising a COS hydrolysis reactor that is fluidly coupled to the first stripper and that is configured to allow for hydrolysis of COS in the CO2/H2-rich recycle gas.