Hydrogen-containing gas producing system and exhaust gas purifying system using same

Abstract

A hydrogen-containing gas producing system of an onboard type, for producing hydrogen-containing gas to be used for purification of exhaust gas of an internal combustion engine. The hydrogen-containing system comprises a fuel supply source for supplying fuel as a raw material of the hydrogen-containing gas. A carrier gas supply source is provided for supplying a carrier gas for carrying the fuel. A device is provided for vaporizing the fuel so as to form a vaporized fuel serving as a reaction gas. The fuel vaporizing device is connected to the fuel supply source and the carrier gas supply source. Additionally, a reforming section is connected to the fuel vaporizing device, for reforming the reaction gas so as to produce the hydrogen-containing gas.

What is claimed is:  
     
         1 . A hydrogen-containing gas producing system of an onboard type, for producing hydrogen-containing gas to be used for purification of exhaust gas of an internal combustion engine, said hydrogen-containing system comprising: 
 a fuel supply source for supplying fuel as a raw material of the hydrogen-containing gas;    a carrier gas supply source for supplying a carrier gas for carrying the fuel;    a device for vaporizing the fuel so as to form a vaporized fuel serving as a reaction gas, -said fuel vaporizing device being connected to said fuel supply source and said carrier gas supply source; and    a reforming section connected to said fuel vaporizing device, for reforming the reaction gas so as to produce the hydrogen-containing gas.    
     
     
         2 . A hydrogen-containing gas producing system as claimed in  claim 1 , wherein the hydrogen-containing gas contains carbon monoxide in an amount of not more than 100 ppm.  
     
     
         3 . A hydrogen-containing gas producing system as claimed in  claim 1 , wherein said fuel supply source is adapted to supply liquid fuel serving as the raw material of the hydrogen-containing gas, said fuel vaporizing device is a gas mixer which is arranged to vaporize the liquid fuel under action of the carrier gas so as to form the vaporized fuel serving as the reaction gas.  
     
     
         4 . A hydrogen-containing gas producing system as claimed in  claim 1 , wherein said reforming section includes a fuel reforming catalyst containing rhodium.  
     
     
         5 . A hydrogen-containing gas producing system as claimed in  claim 1 , further comprising a hydrogen-containing gas storing device for storing the hydrogen-containing gas from said reforming section.  
     
     
         6 . A hydrogen-containing gas producing system as claimed in  claim 1 , wherein said fuel supply source also serves as a fuel supply source for supplying fuel to the internal combustion engine.  
     
     
         7 . A hydrogen-containing gas producing system as claimed in  claim 3 , wherein said reforming section is adapted to produce the hydrogen-containing gas at a reaction temperature of the reaction gas, ranging from 260 to 340° C. and under a condition represented by the following formula:  
       an oxygen concentration in the reaction gas≦an average carbon number of hydrocarbons in the liquid fuel×a concentration of the liquid fuel in the reaction gas×½.  
     
     
         8 . A hydrogen-containing gas producing system as claimed in  claim 3 , wherein the liquid fuel is light oil.  
     
     
         9 . A hydrogen-containing gas producing system as claimed in  claim 3 , wherein the liquid fuel has hydrocarbons whose number of carbon atoms is not smaller than 9.  
     
     
         10 . A hydrogen-containing gas producing system as claimed in  claim 1 , wherein the fuel has hydrocarbons which are separated and extracted from a liquid fuel, each of the hydrocarbons has a number of carbon atoms, not smaller than 9.  
     
     
         11 . An exhaust gas purifying system for an internal combustion engine, comprising: 
 a hydrogen-containing gas producing system of an onboard type, for producing hydrogen-containing gas to be used for purification of exhaust gas of an internal combustion engine, said hydrogen-containing system including a fuel supply source for supplying fuel as a raw material of the hydrogen-containing gas, a carrier gas supply source for supplying a carrier gas for carrying the fuel, a device for vaporizing the fuel so as to form a vaporized fuel as a reaction gas, said fuel vaporizing device being connected to said fuel supply source and said carrier gas supply source, and a reforming section connected to said fuel vaporizing device, for reforming the reaction gas so as to produce the hydrogen-containing gas, said reforming section being connected to a part of an exhaust gas passageway of the internal combustion engine so as to introduce the hydrogen-containing gas into exhaust gas; and    a NOx adsorbing and reducing catalyst disposed in the exhaust gas passageway downstream of said part, said NOx adsorbing and reducing catalyst being adapted to adsorb nitrogen oxides in exhaust gas in a condition that exhaust gas is in a lean region, and to reduce nitrogen oxides in exhaust gas in a condition that exhaust gas is within a range including a stochiometric region and a rich region, wherein the hydrogen-containing gas from said reforming section of said hydrogen-containing gas is supplied into the exhaust gas passageway at said part which is upstream of said NOx adsorbing and reducing catalyst, at a low temperature range in which a temperature of exhaust gas at a position immediately upstream of said NOx adsorbing and reducing catalyst is not higher than 250° C., and in the condition that exhaust gas is within the range including the stoichiometric region and the rich region.    
     
     
         12 . An exhaust gas purifying system as claimed in  claim 11 , further comprising a three-way catalyst disposed in the exhaust gas passageway upstream of said part to which a supply inlet for the hydrogen-containing gas is located.  
     
     
         13 . A hydrogen-containing gas producing system of an onboard type, for producing hydrogen-containing gas to be used for purification of exhaust gas of an internal combustion engine, said hydrogen-containing system comprising: 
 a fuel supply source for supplying fuel as a raw material of the hydrogen-containing gas;    a carrier gas supply source for supplying a carrier gas for carrying the fuel;    means for vaporizing the fuel so as to form a vaporized fuel serving as a reaction gas, said fuel vaporizing means receiving the fuel from said fuel supply source and the carrier gas from said carrier gas supply source; and    a reforming section connected to said fuel vaporizing device, for reforming the reaction gas so as to produce the hydrogen-containing gas.    
     
     
         14 . An exhaust gas purifying system for an internal combustion engine mounted on an automotive vehicle, comprising: 
 a catalyst for reducing nitrogen oxides in exhaust gas of the engine, disposed in an exhaust gas passageway of the engine and mounted on the vehicle, said catalyst containing at least one of platinum and palladium; and    a hydrogen-containing gas producing system for producing hydrogen-containing gas, mounted on the vehicle, said hydrogen-containing system including a fuel supply source for supplying fuel as a raw material of the hydrogen-containing gas, a carrier gas supply source for supplying a carrier gas for carrying the fuel, a device for vaporizing the fuel so as to form a vaporized fuel as a reaction gas, said fuel vaporizing device being connected to said fuel supply source and said carrier gas supply source, and a reforming section connected to said fuel vaporizing device, for reforming the reaction gas so as to produce the hydrogen-containing gas, said reforming section being connected to a part of the exhaust gas passageway upstream of said catalyst so that the hydrogen-containing gas is supplied to said catalyst.