Method and arrangement for utilizing recirculation for high temperature fuel cell system

Abstract

An arrangement utilizing recirculation for high temperature fuel cell system, each fuel cell including an anode side, a cathode side, and an electrolyte between the anode side and the cathode side, wherein the fuel cell system can perform anode side recirculation flow of reactants. The arrangement can accomplish a recycle ratio of 70% or more for the recirculation flow, feed to the recirculation a feed-in flow, which can include substantially high oxygen content, the feed-in flow being 30% or less of entire flow, perform heat exchanging to provide substantially reduced low temperature conditions in the recirculation flow, perform catalytic partial oxidation in the recirculation flow to produce a substantially high amount of hydrogen for the recirculation flow in fuel cell system start-up or shutdown situations, and exhaust 30% or less of the entire flow from the anode side recirculation.

What is claimed is: 
     
         1 . An arrangement utilizing recirculation for a high temperature fuel cell system, each fuel cell in the fuel cell system having an anode side, a cathode side, and an electrolyte between the anode side and the cathode side, the arrangement comprising:
 means for performing anode side recirculation flow of reactants;   means for accomplishing a recycle ratio of about 70% or more for a recirculation flow volume;   means for feeding to the recirculation flow a feed-in flow, which includes an oxygen content, the feed-in flow being about 30% or less of an entire flow volume;   means for performing heat exchanging to reduce temperature conditions in the recirculation flow;   means for performing catalytic partial oxidation in the recirculation flow to produce an amount of hydrogen for the recirculation flow in fuel cell system start-up or shutdown situations; and   means for exhausting about 30% or less of the entire flow volume from the anode side recirculation, the means for performing anode side recirculation and the means for accomplishing the recycle ratio being arranged to provide an inlet temperature of about 350° C. to 500° C. to the means for performing catalytic partial oxidation, and wherein an outlet temperature of the means for performing catalytic partial oxidation will not exceed about 800° C.   
     
     
         2 . An arrangement utilizing recirculation in accordance with  claim 1 , comprising:
 an anode recycle blower, which serves as means for accomplishing a recycle ratio of about 80% to 94% for the recirculation flow volume to produce a gas compound which contains heat from the oxidation performed by the means for performing catalytic partial oxidation.   
     
     
         3 . An arrangement utilizing recirculation in accordance with  claim 1 , wherein the means for feeding to the recirculation is configured to feed to the recirculation flow a feed-in flow, which includes a lambda-value from about 0.55 to 0.90 indicating a high oxygen content of the feed-in flow. 
     
     
         4 . An arrangement utilizing recirculation in accordance with  claim 1 , wherein the means for performing catalytic partial oxidation in the recirculation flow is configured to produce content percent of 3.5% to 15% of hydrogen for the recirculation flow volume as the amount of hydrogen. 
     
     
         5 . An arrangement utilizing recirculation in accordance with  claim 1 , wherein the means for performing catalytic partial oxidation in the recirculation flow is configured to perform catalytic partial oxidation with a mixed feed-in flow and recirculation flow, so that gases in the anode side of the fuel cell system are thermodynamically outside of coking regions during heating, cooling, or operation of the fuel cell system. 
     
     
         6 . An arrangement utilizing recirculation for a high temperature fuel cell system, each fuel cell in the fuel cell system having an anode side, a cathode side, and an electrolyte between the anode side and the cathode side, the fuel cell system comprising:
 a feedback arrangement for performing anode side recirculation flow of reactants;   an anode recycle blower for accomplishing a recycle ratio of about 70% or more for a recirculation flow volume;   a first pipe arrangement for feeding to the recirculation flow, a feed-in flow having an oxygen content, the feed-in flow being about 30% or less of an entire flow volume;   a heat exchanger for performing heat exchanging to reduce temperature conditions in the recirculation flow;   a reformer for performing catalytic partial oxidation in the recirculation flow to produce an high amount of hydrogen for the recirculation flow in fuel cell system start-up or shutdown situations; and   a second pipe arrangement for exhausting about 30% or less of the entire flow volume from the anode side recirculation, and wherein the feedback arrangement and the anode recycle blower are configured to provide an inlet temperature of about 350° C. to 500° C. to the reformer and an outlet temperature of the reformer which does not exceed about 800° C.   
     
     
         7 . An arrangement utilizing recirculation in accordance with  claim 6 , wherein the anode recycle blower is configured to accomplish a recycle ratio of about 80% to 94% for the recirculation flow volume to produce a gas compound which contains heat from the oxidation performed by the reformer. 
     
     
         8 . An arrangement utilizing recirculation in accordance with  claim 6 , wherein the first pipe arrangement is configured to feed to the recirculation flow a feed-in flow, which includes a lambda-value from about 0.55 to 0.90 indicating the oxygen content of the feed-in flow. 
     
     
         9 . An arrangement utilizing recirculation in accordance with  claim 6 , wherein the reformer in the recirculation flow is configured to produce content percent of 3.5% to 15% of hydrogen for the recirculation flow volume as the amount of hydrogen. 
     
     
         10 . An arrangement utilizing recirculation in accordance with  claim 6 , wherein the reformer is configured to perform catalytic partial oxidation with a mixed feed-in flow and recirculation flow, so that gases in the anode side of the fuel cell system are thermodynamically outside of coking regions during heating, cooling, or operation of the fuel cell system. 
     
     
         11 . A method utilizing recirculation for a high temperature fuel cell system, which method performs anode side recirculation flow of reactants, and accomplishes a recycle ratio about 70% or more for a recirculation flow volume, the method comprising:
 feeding to the recirculation flow volume a feed-in flow, which includes an oxygen content, the feed-in flow being about 30% or less of an entire flow volume;   performing heat exchanging to provide substantially reduced temperature conditions in the recirculation flow;   performing catalytic partial oxidation in the recirculation flow to produce an amount of hydrogen for the recirculation flow in fuel cell system during start-up or shutdown situations; and   exhausting about 30% or less of the entire flow volume from the anode side recirculation, wherein the heat exchanging provides an inlet temperature of about 350° C. to about 500° C. to the catalytic partial oxidation and an outlet temperature which does not exceed about 800° C.   
     
     
         12 . A method in accordance with  claim 11 , comprising:
 accomplishing a recycle ratio of 80%-94% for the recirculation flow volume using an anode recycle blower to produce a gas compound, which contains heat from the catalytic partial oxidation.   
     
     
         13 . A method in accordance with  claim 11 , comprising:
 feeding to the recirculation a feed-in flow, which includes a lambda-value from about 0.55 to 0.90 indicating the high oxygen content of the feed-in flow.   
     
     
         14 . A method in accordance with  claim 11 , comprising:
 performing the catalytic partial oxidation in the recirculation flow to produce a content percent of 3.5%-15% of hydrogen for the recirculation flow volume as a high amount of hydrogen.   
     
     
         15 . A method in accordance with  claim 11 , comprising:
 performing the catalytic partial oxidation with a mixed feed-in flow and recirculation flow, so that gases in an anode side of the fuel cell system are thermodynamically outside of coking regions of fuel cell system during heating, cooling or operation of the fuel cell system.