High Temperature Fuel Cell System and Method of Operating the Same

Abstract

A high temperature fuel cell stack system, such as a solid oxide fuel cell system, with an improved balance of plant efficiency includes a thermally integrated reformer, combustor and the fuel cell stack.

1 . A method of operating a solid oxide fuel cell system, comprising:
 operating the fuel cell system in a start-up mode by:
 providing a hydrocarbon fuel and air into a catalytic partial oxidation reactor; 
 generating hydrogen in the catalytic partial oxidation reactor; 
 providing the generated hydrogen into a solid oxide fuel cell stack; and 
 stopping the generation of hydrogen in the catalytic partial oxidation reactor once the fuel cell stack reaches a predetermined operating temperature; and 
   operating the fuel cell system in a steady state operating mode to generate electricity after the fuel cell stack reaches a predetermined operating temperature.   
     
     
         2 . The method of  claim 1 , wherein the predetermined operating temperature is a temperature at which oxidation of anode electrodes of solid oxide fuel cells in the solid oxide fuel cell stack is avoided. 
     
     
         3 . The method of  claim 1 , further comprising heating the catalytic partial oxidation reactor during the start-up mode. 
     
     
         4 . The method of  claim 1 , further comprising mixing the hydrocarbon fuel and air and providing the mixed hydrocarbon fuel and air into the catalytic partial oxidation reactor. 
     
     
         5 . The method of  claim 1 , wherein the hydrocarbon fuel comprises methane or methane containing natural gas. 
     
     
         6 . The method of  claim 1 , wherein the generated hydrogen is provided in the start-up mode from the catalytic partial oxidation reactor into the solid oxide fuel cell stack through a reformer. 
     
     
         7 . The method of  claim 6 , wherein the generated hydrogen is provided in the start-up mode from the solid oxide fuel cell stack into a fuel heat exchanger. 
     
     
         8 . The method of  claim 7 , wherein the generated hydrogen is provided in the start-up mode from the fuel heat exchanger into a combustor. 
     
     
         9 . The method of  claim 1 , wherein the step of stopping the generation of hydrogen in the catalytic partial oxidation reactor comprises stopping operation of the catalytic partial oxidation reactor. 
     
     
         10 . The method of  claim 1 , wherein operating the fuel cell system in a steady state operating mode comprises:
 providing the hydrocarbon fuel and water vapor into a reformer;   reforming the hydrocarbon fuel in the reformer to form a hydrogen containing reaction product; and   providing the reaction product and air into the solid oxide fuel cell stack during the steady state operating mode of the stack.   
     
     
         11 . The method of  claim 10 , wherein operating the fuel cell system in a steady state operating mode further comprises:
 providing the hydrocarbon fuel into a fuel heat exchanger;   providing the hydrocarbon fuel from the fuel exchanger into the reformer;   providing the air into an air heat exchanger; and   providing the air from the air heat exchanger into the solid oxide fuel cell stack.   
     
     
         12 . The method of  claim 11 , wherein operating the fuel cell system in a steady state operating mode further comprises:
 providing an anode exhaust from the solid oxide fuel cell stack into the fuel heat exchanger to heat the hydrocarbon fuel;   providing at least a portion of the anode exhaust from the fuel heat exchanger into a combustor;   providing a cathode exhaust from the solid oxide fuel cell stack into the combustor; and   providing a combustor exhaust into the air heat exchanger to heat the air.   
     
     
         13 . The method of  claim 1 , wherein operating the fuel cell system in a start-up mode further comprises:
 providing the generated hydrogen from the catalytic partial oxidation reactor a reformer;   providing the generated hydrogen from the reformer into the solid oxide fuel cell stack;   providing the generated hydrogen from the solid oxide fuel cell stack into a fuel heat exchanger; and   providing the generated hydrogen from the fuel heat exchanger into a combustor.   
     
     
         14 . The method of  claim 13 , wherein operating the fuel cell system in a steady state operating mode comprises:
 providing the hydrocarbon fuel into a fuel heat exchanger;   providing the hydrocarbon fuel from the fuel exchanger into the reformer;   providing water vapor into the reformer;   reforming the hydrocarbon fuel in the reformer to form a hydrogen containing reaction product;   providing the reaction product into the solid oxide fuel cell stack;   providing the air into an air heat exchanger;   providing the air from the air heat exchanger into the solid oxide fuel cell stack;   providing an anode exhaust from the solid oxide fuel cell stack into the fuel heat exchanger to heat the hydrocarbon fuel;   providing at least a portion of the anode exhaust from the fuel heat exchanger into a combustor;   providing a cathode exhaust from the solid oxide fuel cell stack into the combustor; and   providing a combustor exhaust into the air heat exchanger to heat the air.