Fuel cell power generation system

Abstract

A stable and high reliability fuel cell electricity-generating device capable of generating electricity even in the case of sudden drop of load power. A fuel cell generating electric power from a fuel and an oxidizer, a fuel processor producing fuel to be supplied into the fuel cell from an electricity-generating material, a combustion device combusting a residual fuel gas unconsumed in the fuel cell to raise the temperature of the fuel processor, and an electric power generation instructing means of determining the electric power generated by the fuel cell, wherein when the electric power generation instructing means decreases the electric power generated by the fuel cell depending on the decrease of load power to be supplied, the rate at which the generated electric power is decreased is made different depending on the change of the temperature of the fuel processor.

1 . A fuel cell electricity-generating device comprising: 
 a fuel cell generating electric power from a fuel and an oxidizer,    a fuel processor producing the fuel to be supplied into said fuel cell from an electricity-generating material,    a combustion device combusting a residual fuel gas unconsumed in said fuel cell to raise the temperature of said fuel processor, and    an electric power generation instructing means of determining the electric power generated by said fuel cell,    wherein when said electric power generation instructing means decreases the electric power generated by said fuel cell depending on the decrease of load power to be supplied, the rate at which the generated electric power is decreased is made different depending on the change of the temperature of the fuel processor.    
     
     
         2 . The fuel cell electricity-generating device as described in  claim 1 , wherein the generated electric power is decreased at a rate with a predetermined upper-limit while the temperature of said fuel processor is rising but at unlimited rate while the temperature of said fuel processor is not rising.  
     
     
         3 . A fuel cell electricity-generating device comprising: 
 a fuel cell generating electric power from a fuel and an oxidizer,    a fuel processor of producing a fuel to be supplied into said fuel cell from an electricity-generating material,    a combustion device combusting a residual fuel gas unconsumed in said fuel cell to raise the temperature of said fuel processor, and    an electric power generation instructing means of determining the electric power generated by said fuel cell,    wherein when said electric power generation instructing means decreases the electric power generated by said fuel cell depending on the decrease of load power to be supplied, the rate at which the generated electric power is decreased is made different depending on the temperature of the fuel processor.    
     
     
         4 . The fuel cell electricity-generating device according to  claim 3  wherein a first power limitation mode preventing the decrease of generated electric power is executed when the temperature of said fuel processor is not lower than a first threshold value and the rate at which the generated electric power is decreased is not limited when the temperature of said fuel processor is not higher than a second threshold value which is lower than the first threshold value.  
     
     
         5 . The fuel cell electricity-generating device according to  claim 4  wherein said first power limitation mode is released when said electric power generation instructing means maintains or begins to raise the electric power generated by said fuel cell.  
     
     
         6 . The fuel cell electricity-generating device according to  claim 3  wherein a second power limitation mode of decreasing the generated electric power at a rate with a predetermined upper limit is executed when the temperature of said fuel processor is not lower than a third threshold value, and the rate at which the generated electric power is decreased is not limited when the temperature of said fuel processor is not higher than a fourth threshold value which is lower than the third threshold value.  
     
     
         7 . The fuel cell electricity-generating device according to  claim 6  wherein said second power limitation mode is released when said electric power generation instructing means maintains or begins to raise the electric power generated by said fuel cell.  
     
     
         8 . The fuel cell electricity-generating device according to  claim 3  wherein a first power limitation mode of preventing the decrease of generated electric power is executed when the temperature of said fuel processor is not lower than the first threshold value, a second power limitation mode of decreasing the generated electric power at a rate with a predetermined upper limit is executed when the temperature of said fuel processor is not higher than the second threshold value, which is lower than said first threshold value and the rate at which the generated electric power is decreased is not limited when the temperature of said fuel processor is not higher than the fourth threshold value which is lower than the second threshold value.  
     
     
         9 . The fuel cell electricity-generating device according to  claim 8  wherein both of said first and second power limitation modes are released when said electric power generation instructing means maintains or begins to raise the electric power generated by said fuel cell.  
     
     
         10 . A fuel cell electricity-generating method of generating electricity using a fuel cell comprising the steps of: 
 generating electric power in said fuel cell from a fuel and an oxidizer,    producing in a fuel processor a fuel to be supplied into said fuel cell from an electricity-generating material,    combusting a residual fuel gas unconsumed in said fuel cell to raise the temperature of said fuel processor, and    determining in an electric power generation instructing means the electric power generated by said fuel cell,    wherein there is provided a step of making the rate at which the generated electric power is decreased different depending on the change of the temperature of the fuel processor when said electric power generation instructing means decreases the electric power generated by said fuel cell depending on the decrease of load power to be supplied.    
     
     
         11 . A fuel cell electricity-generating method of generating electricity using a fuel cell comprising the steps of: 
 generating electric power in said fuel cell from a fuel and an oxidizer,    producing in a fuel processor a fuel to be supplied into said fuel cell from an electricity-generating material,    combusting a residual fuel gas unconsumed in said fuel cell to raise the temperature of said fuel processor, and    determining in an electric power generation instructing means the electric power generated by said fuel cell,    wherein there is provided a step of making the rate at which the generated electric power is decreased different depending on the temperature of the fuel processor when said electric power generation instructing means decreases the electric power generated by said fuel cell depending on the decrease of load power to be supplied.