Method and system for producing dry gas

Abstract

A system and method for producing dry gas, such as methane or carbon dioxide, incorporates an electrochemical device that removes water and hydrogen from a mixed gas stream. The electrochemical device uses one electrochemical cell to strip hydrogen and water from the mixed gas stream and a second electrochemical cell, combined with a dry feed stream, to remove any residual water from the mixed stream and produce pure, dry gas.

What is claimed is:  
     
         1 . An electrochemical device for a gas production system, comprising: 
 a first electrochemical cell that receives a mixed gas stream containing at least a desired gas, hydrogen and water, wherein the first electrochemical cell removes at least a portion of the water from the mixed gas stream to form a mixed gas stream having residual water; and    a second electrochemical cell that receives the mixed gas stream and a dry feed stream, wherein the second electrochemical cell removes the residual water from the mixed gas stream and wherein the dry feed stream absorbs the residual water to obtain the desired gas.    
     
     
         2 . The electrochemical device of  claim 1 , wherein the dry feed stream is hydrogen.  
     
     
         3 . The electrochemical device of  claim 1 , wherein the first electrochemical cell removes the hydrogen from the mixed gas stream along with said at least a portion of the water.  
     
     
         4 . The electrochemical device of  claim 1 , wherein the electrochemical device feeds the mixed gas stream on an anode side of the second electrochemical cell and feeds the dry feed stream on a cathode side of the second electrochemical cell.  
     
     
         5 . The electrochemical device of  claim 1 , further comprising a third electrochemical cell that receives the dry feed stream after the dry feed stream has absorbed the residual water from the mixed gas stream, wherein the third electrochemical cell outputs the dry feed stream and the residual water in a metered fashion.  
     
     
         6 . The electrochemical device of  claim 1 , wherein the desired gas is one selected from the group consisting of methane and carbon dioxide.  
     
     
         7 . A methane production system, comprising: 
 an electrolyzer that receives a first stream containing carbon dioxide and water and outputs a second stream containing carbon dioxide and hydrogen;    a Sabatier reactor that receives the second stream from the electrolyzer and outputs a methane stream containing methane, hydrogen and water; and    an electrochemical device comprising 
 a first electrochemical cell that receives the methane stream, wherein the first electrochemical cell removes at least a portion of the water from the methane stream having residual water, and  
 a second electrochemical cell that receives the methane stream and a dry feed stream, wherein the second electrochemical cell removes the residual water from the methane stream and wherein the dry feed stream absorbs the residual water.  
   
     
     
         8 . The methane production system of  claim 7 , wherein the electrochemical device feeds the methane stream on an anode side of the second electrochemical cell and feeds the dry feed stream on a cathode side of the second electrochemical cell.  
     
     
         9 . The methane production system of  claim 7 , further comprising a third electrochemical cell that receives the dry feed stream after the dry feed stream has absorbed the residual water, wherein the third electrochemical cell outputs the dry feed stream and the residual water in a metered fashion to the electrolyzer.  
     
     
         10 . A method for producing a dry desired gas, comprising: 
 obtaining a mixed gas stream containing the desired gas, hydrogen and water;    feeding the mixed gas stream and a dry feed stream into an electrochemical device;    removing the hydrogen and the water from the mixed gas stream via the electrochemical device, wherein the dry feed stream absorbs at least a portion of the water from the mixed gas stream to produce the dry desired gas.    
     
     
         11 . The method of  claim 10 , wherein the electrochemical device comprises a first electrochemical cell and a second electrochemical cell, and wherein the removing step comprises: 
 removing at least a portion of the water from the mixed gas stream via the first electrochemical cell to form a gas stream having residual water;    sending the gas stream having residual water and the dry feed stream to the second electrochemical cell, wherein the dry feed stream absorbs the residual water to produce the dry desired gas.    
     
     
         12 . The method of  claim 10 , further comprising directing the dry feed stream to an electrolyzer after the dry feed stream has absorbed the residual water.