Carbon capture with molten carbonate electrolysis cell

Abstract

Systems and methods are provided for integration of molten carbonate electrolysis cells in applications for hydrogen production and for operating turbines using oxycombustion. In some aspects, the unusual output flows from an MCEC (or more typically a plurality of MCECs) can be synergistically used in combination with reverse flow reactors and/or partial oxidation units to allow for hydrogen production while also performing carbon capture. In other embodiments, the anode output from an MCEC (or a plurality of MCECs) can be used as the oxygen-containing gas for a combustion turbine or a furnace.

What is claimed is: 
     
         1 . A method for operating a molten carbonate electrolysis cell, comprising:
 passing a cathode input flow comprising
 3.0 vol % or more H 2 O, and 
 3.0 vol % or more of CO 2 , a reformable hydrocarbon, or a combination thereof, into a cathode of a molten carbonate electrolysis cell; 
   providing electric current to the cathode of the molten carbonate electrolysis cell;   operating the molten carbonate electrolysis cell to produce a cathode output flow comprising H 2 , H 2 O, and CO 2 , and an anode output flow comprising CO 2  and O 2 , the H 2 O content of the cathode output flow being lower than the H 2 O content of the cathode input flow;   mixing at least a portion of the anode output flow with fuel; and   reacting the at least a portion of the anode output flow and the fuel under at least one of combustion conditions and partial oxidation conditions to form a reaction effluent.   
     
     
         2 . The method of  claim 1 , wherein the CO 2  content of the cathode output flow is lower than the CO 2  content of the cathode input flow. 
     
     
         3 . The method of  claim 1 , wherein the cathode input flow comprises 3.0 vol % or more of CO 2 . 
     
     
         4 . The method of  claim 1 , wherein the anode output flow comprises 0 vol % to 5.0 vol % of N 2 , or wherein the anode output flow comprises less than 0.1 vol % of N 2 . 
     
     
         5 . The method of  claim 1 , wherein the anode output flow comprises 5.0 vol % or more of O 2 . 
     
     
         6 . The method of  claim 1 , wherein the method further comprises passing a sweep gas into the anode of the molten carbonate electrolysis cell, the sweep gas optionally comprising H 2 O. 
     
     
         7 . The method of  claim 1 , wherein the cathode input flow comprises a reformable hydrocarbon, and wherein operating the molten carbonate electrolysis cell further comprises reforming at least a portion of the reformable hydrocarbon. 
     
     
         8 . The method of  claim 7 , the method further comprising passing an anode input flow into the anode, the anode input flow comprising a second fuel and O 2 , wherein at least a portion of the second fuel and at least a portion of the O 2  in the anode input flow are combusted in the anode. 
     
     
         9 . The method of  claim 8 , wherein the anode input flow comprises at least a portion of the anode output flow. 
     
     
         10 . The method of  claim 8 , wherein the second fuel comprises H 2  separated from the cathode output flow. 
     
     
         11 . The method of  claim 7 , wherein the reformable hydrocarbon comprises methane. 
     
     
         12 . The method of  claim 1 , wherein the at least a portion of the anode output flow and the fuel are reacted under combustion conditions as a regeneration step in a reverse flow reactor to form a regeneration effluent, the reacting under combustion conditions comprising heating one or more surfaces in the reverse flow reactor to a regeneration temperature of 800° C. or more, the one or more surfaces comprising reforming catalyst, the method further comprising:
 passing reformable fuel and steam into the reverse flow reactor; 
 reforming at least a portion of the reformable fuel in the presence of the reforming catalyst to produce a reforming effluent, the one or more surfaces being cooled to a temperature below the regeneration temperature, 
 wherein the cathode input flow comprises at least a portion of the reforming effluent. 
 
     
     
         13 . The method of  claim 12 , wherein the at least a portion of the anode output flow and the fuel are combined with at least a portion of the regeneration effluent prior to the reacting under combustion conditions. 
     
     
         14 . The method of  claim 1 , wherein the at least a portion of the anode output flow and the fuel are reacted under partial oxidation conditions to form a partial oxidation effluent, the method further comprising:
 passing the partial oxidation effluent into a water gas shift stage to form a shifted partial oxidation effluent,   wherein the cathode input flow comprises at least a portion of the shifted partial oxidation effluent.   
     
     
         15 . The method of  claim 1 , wherein the at least a portion of the anode output flow and the fuel are reacted under combustion conditions in a combustion zone of a turbine. 
     
     
         16 . The method of  claim 1 , wherein the at least a portion of the anode output flow and the fuel are reacted under combustion conditions in a furnace. 
     
     
         17 . A method for operating a molten carbonate electrolysis cell, comprising:
 passing a cathode input flow comprising 5.0 vol % or more H 2 , 3.0 vol % or more H 2 O, and 3.0 vol % or more of CO 2 , into a cathode of a molten carbonate electrolysis cell;   providing electric current to the cathode of the molten carbonate electrolysis cell; and   operating the molten carbonate electrolysis cell to produce a cathode output flow comprising H 2 , H 2 O, and CO 2 , and an anode output flow comprising CO 2  and O 2 , the CO 2  content of the cathode output flow being lower than the CO 2  content of the cathode input flow, the H 2 O content of the cathode output flow being lower than the H 2 O content of the cathode input flow.   
     
     
         18 . The method of  claim 17 , wherein the cathode input flow comprises a reforming effluent. 
     
     
         19 . The method of  claim 17 , wherein the cathode input flow comprises 10 vol % or more H 2 . 
     
     
         20 . The method of  claim 17 , wherein the cathode input flow comprises a reformable hydrocarbon, and wherein operating the molten carbonate electrolysis cell further comprises reforming at least a portion of the reformable hydrocarbon. 
     
     
         21 . The method of  claim 17 , wherein at least a portion of the anode output flow and a fuel are reacted under combustion conditions as a regeneration step in a reverse flow reactor to form a regeneration effluent, the reacting under combustion conditions comprising heating one or more surfaces in the reverse flow reactor to a regeneration temperature of 800° C. or more, the one or more surfaces comprising reforming catalyst, the method further comprising:
 passing reformable fuel and steam into the reverse flow reactor; 
 reforming at least a portion of the reformable fuel in the presence of the reforming catalyst to produce a reforming effluent, the one or more surfaces being cooled to a temperature below the regeneration temperature, 
 wherein the cathode input flow comprises at least a portion of the reforming effluent. 
 
     
     
         22 . The method of  claim 17 , wherein at least a portion of the anode output flow and a fuel are reacted under partial oxidation conditions to form a partial oxidation effluent, the method further comprising:
 passing the partial oxidation effluent into a water gas shift stage to form a shifted partial oxidation effluent,   wherein the cathode input flow comprises at least a portion of the shifted partial oxidation effluent.   
     
     
         23 . The method of  claim 17 , wherein at least a portion of the anode output flow and a fuel are reacted under combustion conditions in a combustion zone of a turbine; or wherein at least a portion of the anode output flow and a fuel are reacted under combustion conditions in a furnace.