Catalytic combustor and fuel cell system

Abstract

A catalytic combustor is provided with a housing supplied with mixed gas including exhaust fuel gas from a fuel electrode of a fuel cell and exhaust oxidizer gas from an oxidizer electrode of the fuel cell, and a catalyst combusting the mixed gas. At an area upstream of the catalyst, an inner periphery surface of the housing has a continuous shape, and at least one of the exhaust fuel gas and the exhaust oxidizer gas is supplied to the housing in a way to generate swirl flow in the mixed gas so as to swirl along the inner peripheral surface. Such a catalytic combustor is applied to a fuel cell system provided with a fuel cell having a fuel electrode and an oxidizer electrode.

What is claimed is:  
     
         1 . A catalytic combustor comprising: 
 a housing supplied with mixed gas including exhaust fuel gas from a fuel electrode of a fuel cell and exhaust oxidizer gas from an oxidizer electrode of the fuel cell; and    a catalyst combusting the mixed gas,    wherein at an area upstream of the catalyst, an inner periphery surface of the housing has a continuous shape, and at least one of the exhaust fuel gas and the exhaust oxidizer gas is supplied to the housing in a way to generate swirl flow in the mixed gas so as to swirl along the inner peripheral surface.    
     
     
         2 . The catalytic combustor according to  claim 1 , wherein the inner peripheral surface is a cylindrical surface.  
     
     
         3 . The catalytic combustor according to  claim 1 , wherein supplying at least one of the exhaust fuel gas and the exhaust oxidizer gas into the housing while causing swirl flow to occur therein allows the swirl flow to occur in the mixed gas.  
     
     
         4 . The catalytic combustor according to  claim 3 , wherein an exhaust fuel supply port supplying the exhaust fuel gas to the housing is placed in opposition to the catalyst and disposed along a central axis of the inner peripheral surface of the housing.  
     
     
         5 . The catalytic combustor according to  claim 4 , wherein the exhaust fuel supply port causes the swirl flow in the exhaust fuel gas.  
     
     
         6 . The catalytic combustor according to  claim 3 , wherein an exhaust oxidizer supply port supplying the exhaust oxidizer gas to the housing includes a portion connected to the inner peripheral surface of the housing in a tangential direction thereof.  
     
     
         7 . The catalytic combustor according to  claim 6 , wherein the exhaust oxidizer supply port causes swirl flow to occur in the exhaust oxidizer gas.  
     
     
         8 . The catalytic combustor according to  claim 3 , wherein an exhaust fuel supply port supplying the exhaust fuel gas to the housing is disposed in an exhaust oxidizer supply port supplying the exhaust oxidizer gas to the housing so as to allow the exhaust fuel gas to be supplied in a direction as same as that of the exhaust oxidizer gas.  
     
     
         9 . The catalytic combustor according to  claim 1 , wherein the inner peripheral surface of the housing includes an annular protrusion that protrudes inward from the inner peripheral surface at an area upstream of the catalyst.  
     
     
         10 . A fuel cell system comprising: 
 a fuel cell having a fuel electrode and an oxidizer electrode; and    a catalytic combustor provided with: 
 a housing supplied with mixed gas including exhaust fuel gas from a fuel electrode of a fuel cell and exhaust oxidizer gas from an oxidizer electrode of the fuel cell; and  
 a catalyst combusting the mixed gas,  
   wherein at an area upstream of the catalyst, an inner periphery surface of the housing has a continuous shape, and at least one of the exhaust fuel gas and the exhaust oxidizer gas is supplied to the housing in a way to generate swirl flow in the mixed gas so as to swirl along the inner peripheral surface.    
     
     
         11 . The fuel cell system according to  claim 10 , further comprising: 
 a recirculation passage supplying the exhaust fuel gas from the fuel electrode to the fuel electrode;    an exhaust fuel gas supply passage supplying the exhaust fuel gas from a midcourse of the recirculation passage to the catalytic combustor; and    a valve disposed in the recirculation passage and operative to be opened to supply the exhaust fuel gas to the catalytic combustor.    
     
     
         12 . The fuel cell system according to  claim 10 , wherein the inner peripheral surface is a cylindrical surface.  
     
     
         13 . The fuel cell system according to  claim 10 , wherein supplying at least one of the exhaust fuel gas and the exhaust oxidizer gas into the housing while causing swirl flow to occur therein allows the swirl flow to occur in the mixed gas.  
     
     
         14 . The fuel cell system according to  claim 13 , wherein an exhaust fuel supply port supplying the exhaust fuel gas to the housing is placed in opposition to the catalyst and disposed along a central axis of the inner peripheral surface of the housing.  
     
     
         15 . The fuel cell system according to  claim 14 , wherein the exhaust fuel supply port causes the swirl flow in the exhaust fuel gas.  
     
     
         16 . The fuel cell system according to  claim 13 , wherein an exhaust oxidizer supply port supplying the exhaust oxidizer gas to the housing includes a portion connected to the inner peripheral surface of the housing in a tangential direction thereof.  
     
     
         17 . The fuel cell system according to  claim 16 , wherein the exhaust oxidizer supply port causes swirl flow to occur in the exhaust oxidizer gas.  
     
     
         18 . The fuel cell system according to  claim 13 , wherein an exhaust fuel supply port supplying the exhaust fuel gas to the housing is disposed in an exhaust oxidizer supply port supplying the exhaust oxidizer gas to the housing so as to allow the exhaust fuel gas to be supplied in a direction as same as that of the exhaust oxidizer gas.  
     
     
         19 . The fuel cell system according to  claim 10 , wherein the inner peripheral surface of the housing includes an annular protrusion that protrudes inward from the inner peripheral surface at an area upstream of the catalyst.  
     
     
         20 . A method of supplying gas to a catalytic combustor provided with a housing supplied with mixed gas including exhaust fuel gas from a fuel electrode of a fuel cell and exhaust oxidizer gas from an oxidizer electrode of the fuel cell, and a catalyst combusting the mixed gas, wherein at an area upstream of the catalyst, an inner periphery surface of the housing has a continuous shape, the method comprising: 
 supplying at least one of the exhaust fuel gas and the exhaust oxidizer gas to the housing so as to generate swirl flow to occur in the mixed gas so as to swirl along the inner peripheral surface.