Hydrogen generator and fuel cell system using the same

Abstract

The hydrogen generator includes: a reformer 101 having a reforming catalyst configured to cause a source material and water to react with each other to generate a hydrogen-rich reformed gas; a reformer heater 104 configured to heat the reformer; a carbon monoxide reducing portion 111,121 having a carbon monoxide reducing catalyst configured to reduce carbon monoxide contained in the reformed gas; a carbon monoxide reduction heater 112,123 configured to heat at least one of the carbon monoxide reducing portion, the carbon monoxide reducing catalyst and the reformed gas passing through the carbon monoxide reducing portion; and a controller 200 capable of control such that the carbon monoxide reduction heater is caused to operate in a stop operation period.

1 . A hydrogen generator comprising: 
 a reformer having a reforming catalyst configured to cause a source material and water to react with each other to generate a hydrogen-rich reformed gas;    a reformer heater configured to heat said reformer;    a carbon monoxide reducing portion having a carbon monoxide reducing catalyst configured to reduce carbon monoxide contained in the reformed gas;    a carbon monoxide reduction heater configured to heat at least one of said carbon monoxide reducing portion, the carbon monoxide reducing catalyst and the reformed gas passing through said carbon monoxide reducing portion; and    a controller configured to perform control such that said carbon monoxide reduction heater is caused to operate in a stop operation period in a manner that a temperature of said carbon monoxide reducing portion is kept higher than a first predetermined temperature which fails to allow steam present within said carbon monoxide reducing portion to condense.    
     
     
         2 . The hydrogen generator according to  claim 1 , wherein 
 said carbon monoxide reducing portion comprises at least one of a shifter and a carbon monoxide removing portion,    said carbon monoxide reduction heater comprises at least one of a shifter heater and a carbon monoxide removing portion heater,    said shifter has a carbon monoxide reducing catalyst comprising a shift reaction catalyst, and    said carbon monoxide removing portion has a carbon monoxide reducing catalyst comprising at least one of a selective oxidization catalyst and a methanation catalyst.    
     
     
         3 . The hydrogen generator according to  claim 1 , further comprising: 
 a carbon monoxide reducing portion temperature sensor configured to detect a temperature of said carbon monoxide reducing portion, wherein    said controller is configured to perform control such that said carbon monoxide reduction heater is caused to operate in the stop operation period for at least a time period during which the temperature of said carbon monoxide reducing portion is not higher than the first predetermined temperature.    
     
     
         4 . The hydrogen generator according to  claim 1 , wherein said controller is configured to perform control such that said carbon monoxide reduction heater is caused to operate in response to a stop instruction to initiate a stop operation in the stop operation period.  
     
     
         5 . The hydrogen generator according to  claim 4 , wherein said controller is configured to perform control such that said carbon monoxide reduction heater is caused to stop operating after lapse of a predetermined time period from issuance of the stop instruction in the stop operation period.  
     
     
         6 . The hydrogen generator according to  claim 1 , further comprising: 
 a reformer temperature sensor configured to detect a temperature of said reformer, wherein    said controller is configured to perform a control process in the stop operation period, the control process including: stopping supply of the source material and supply of water; causing said carbon monoxide reduction heater to operate; supplying the source material to purge an interior of the hydrogen generator when the temperature detected by said reformer temperature sensor becomes a temperature which fails to allow carbon to be deposited on the reforming catalyst; and stopping the supply of the source material and the operation of said carbon monoxide reduction heater.    
     
     
         7 . The hydrogen generator according to  claim 1 , further comprising: 
 a first purge gas supply portion configured to supply a first purge gas;    a second purge gas supply portion configured to supply a second purge gas; and    a reformer temperature sensor configured to detect a temperature of said reformer, wherein    said controller is configured to perform control in the stop operation period such that:    when the temperature detected by said reformer temperature sensor is lower than a second predetermined temperature, said second purge gas supply portion is caused to operate until said hydrogen generator becomes fully filled with the second purge gas, and    when the temperature detected by said reformer temperature sensor is not lower than the second predetermined temperature, said first purge gas supply portion is caused to operate until the temperature detected by said reformer temperature sensor becomes lower than the second predetermined temperature and then said second purge gas supply portion is caused to operate until said hydrogen generator becomes fully filled with the second purge gas.    
     
     
         8 . The hydrogen generator according to  claim 7 , wherein 
 the first purge gas is steam,    the second purge gas is air, and    the second predetermined temperature is a temperature which fails to allow the reforming catalyst to be oxidized.    
     
     
         9 . The hydrogen generator according to  claim 7 , wherein 
 the first purge gas is steam,    the second purge gas is the source material, and    the second predetermined temperature is a temperature which fails to allow carbon to be deposited on the reforming catalyst.    
     
     
         10 . The hydrogen generator according to  claim 7 , wherein the first purge gas is one of a combustion exhaust gas and an inert gas.  
     
     
         11 . A fuel cell system comprising: 
 a hydrogen generator including: 
 a reformer having a reforming catalyst configured to cause a source material and water to react with each other to generate a hydrogen-rich reformed gas;  
 a reformer heater configured to heat said reformer;  
 a carbon monoxide reducing portion having a carbon monoxide reducing catalyst configured to reduce carbon monoxide contained in the reformed gas;  
 a carbon monoxide reduction heater configured to heat at least one of said carbon monoxide reducing portion, the carbon monoxide reducing catalyst and the reformed gas passing through said carbon monoxide reducing portion; and  
 a controller configured to perform control such that said carbon monoxide reduction heater is caused to operate in a stop operation period in a manner that a temperature of said carbon monoxide reducing portion is kept higher than a first predetermined temperature which fails to allow steam present within said carbon monoxide reducing portion to condense; and  
   a fuel cell configured to generate electric power using hydrogen generated by said hydrogen generator.