Reducing oxides of nitrogen using reformate generated from engine fuel, water and/or air

Abstract

Inlet air ( 15 ) humidified in an air bubbling (or other) humidifier ( 35 ) that receives water from a tank ( 36 ) is sent to a hydrogen generator ( 27 ) along with vaporized ( 23 ) diesel fuel ( 22 ) to produce hydrogen and carbon monoxide ( 28 ) for either (a) mixing with the mainstream of exhaust ( 18 ) fed to a catalytic converter ( 30 ) or (b) regenerating a pair of NOx adsorption traps ( 38, 39 ), thereby reducing oxides of nitrogen (NOx), to provide system exhaust ( 32 ) which may have less than 0.40 grams/bhp/hr of NOx and 0.28 grams/bhp/hr of non-methane hydrocarbons. In other embodiments, unhumidified air mixed with fuel feeds a homogeneous non-catalytic partial oxidizer ( 27 ) to provide the required hydrogen and carbon monoxide.

I claim:  
     
         1 . A system using reformate for reducing oxides of nitrogen (NOx) in the exhaust of a hydrocarbon-fueled, internal combustion engine which operates with fuel from a source and air from an air inlet and which provides engine exhaust in an exhaust pipe, comprising: 
 reformate means having an inlet and an outlet for providing at its outlet a flow of said reformate including at least hydrogen, said means comprising either (a) a hydrogen generator and a tank of water, said hydrogen generator receiving, at its inlet, air from said air inlet humidified with moisture from said tank and fuel from said source, or (b) a homogeneous non-catalytic partial oxidizer receiving at its inlet fuel from said source and unhumidified air from said air inlet; and    NOx reducing means receiving said engine exhaust and said reformate for reducing the NOx in said engine exhaust to provide system exhaust with diminished NOx.    
     
     
         2 . A system according to  claim 1  wherein said output of said reducing means comprises no more than about 0.4 grams/bhp/hr NOx.  
     
     
         3 . A system according to  claim 1  wherein said output of said reducing means comprises no more than about 0.28 grams/bhp/hr of non-methane hydrocarbons.  
     
     
         4 . A system according to  claim 1  further comprising: 
 a heat exchanger for vaporizing engine fuel before it is added into said mixture.  
 
     
     
         5 . A system according to  claim 1  wherein said reformate means comprises an air bubbler which humidifies air.  
     
     
         6 . A system according to  claim 5  wherein said air bubbler is separate from said tank.  
     
     
         7 . A system according to  claim 5  further comprising: 
 a heat exchanger receiving humidified air out of said air bubbler to heat the humidified air with hot engine exhaust.  
 
     
     
         8 . A system according to  claim 1  wherein said NOx reducing means comprises at least one NOx trap, each NOx trap alternately trapping NOx in said exhaust and being regenerated by said outflow of reformate.  
     
     
         9 . A system according to  claim 1  wherein said NOx reducing means comprises an NOx reducing catalytic converter.  
     
     
         10 . A system according to  claim 1  wherein said hydrogen generator is selected from an auto-thermal reformer, a catalytic partial oxidizer and a homogeneous non-catalytic partial oxidizer.  
     
     
         11 . Apparatus for diminishing oxides of nitrogen (NOx) in the exhaust of a system including a hydrocarbon-fueled engine that provides engine exhaust containing NOx, said apparatus comprising: 
 a tank of water;    means for generating reformate from a mixture of air humidified with moisture derived from said tank of water and engine fuel, to provide a flow of reformate including hydrogen and carbon monoxide; and    means for using the flow of reformate for reducing NOx in said engine exhaust to provide system exhaust with diminished NOx.    
     
     
         12 . A method of diminishing oxides of nitrogen (NOx) in the exhaust of a system including a hydrocarbon-fueled engine that provides engine exhaust containing NOx, said method comprising: 
 generating reformate from a mixture of air humidified by moisture derived from a tank of water and engine fuel, to provide a flow of reformate including hydrogen and carbon monoxide; and    using the flow of reformate for reducing NOx in said engine exhaust to provide system exhaust with diminished NOx.    
     
     
         13 . A method according to  claim 12  wherein: 
 said generating step comprises reforming a mixture containing vaporized fuel.  
 
     
     
         14 . A method according to  claim 13  wherein: 
 said generating step comprises vaporizing fuel by heat exchange with said exhaust.  
 
     
     
         15 . A method according to  claim 12  wherein: 
 said generating step comprises humidifying air in an air bubbling humidifier receiving water from said tank of water.  
 
     
     
         16 . A method according to  claim 12  wherein: 
 said generating step comprises humidifying air in an air bubbling humidifier which serves as said tank for said water.  
 
     
     
         17 . A method according to  claim 12  wherein: 
 said step of reducing NOx comprises applying said exhaust and said flow, contemporaneously, to a NOx reducing catalytic converter.  
 
     
     
         18 . A system according to  claim 12  wherein: 
 said step of reducing NOx comprises alternately applying said engine exhaust and said flow to at least one NOx trap, separately.  
 
     
     
         19 . Apparatus for diminishing oxides of nitrogen (NOx) in the exhaust of a system including a hydrocarbon-fueled engine having an air inlet that provides engine exhaust containing NOx, said apparatus comprising: 
 means including a homogeneous, non-catalytic partial oxidizer (POx) for generating reformate from unhumidified air from said air inlet and engine fuel, to provide a flow of reformate including hydrogen and carbon monoxide; and    means for using the flow of reformate for reducing NOx in said engine exhaust to provide system exhaust with diminished NOx.    
     
     
         20 . A method of diminishing oxides of nitrogen (NOx) in the exhaust of a system including a hydrocarbon-fueled engine having an air inlet that provides engine exhaust containing NOx, said method comprising: 
 generating reformate in a homogeneous, non-catalytic partial oxidizer from unhumidified air from said air inlet and engine fuel, to provide a flow of reformate including hydrogen and carbon monoxide; and    using the flow of reformate for reducing NOx in said engine exhaust to provide system exhaust with diminished NOx.