Process for the catalytic NOx reduction of a thermal engine, and device for said purpose

Abstract

In a process for the catalytic NO x reduction in oxygen-containing exhaust gases of a thermal engine in one or several reduction catalytic converters, hydrocarbons of the fuel of the thermal engine are used in the reduction catalytic converter(s). In order to avoid toxic or dangerous substances and gases, respectively, during said NO x reduction, the process is characterized by the use of a gas mixture as a reducing agent for the reduction catalytic converter(s), which gas mixture is produced in a controlled manner from the fuel of the thermal engine in a catalytic reformer and/or in a fuel cell.

1 . A process for catalytic NO x  reduction in oxygen-containing exhaust gases of a thermal engine in one or several reduction catalytic converters, comprising using hydrocarbons of the fuel of the thermal engine in the reduction catalytic converter(s), and using a gas mixture as a reducing agent for the reduction catalytic converter(s), and producing the gas mixture in a controlled manner in a fuel cell from fuel of the thermal engine.  
   
   
       2 . A process according to  claim 1 , further comprising producing the gas mixture in a controlled manner from the fuel of the thermal engine in a catalytic reformer and in a fuel cell.  
   
   
       3 . A process according to  claim 2 , further comprising supplying the gas mixture produced in the catalytic reformer to the fuel cell for further processing.  
   
   
       4 . A process according to  claim 2 , further comprising supplying a portion of the gas mixture produced in the catalytic reformer to the fuel cell and mixing a portion with the gas mixture processed in the fuel cell and using it as a reducing agent.  
   
   
       5 . A process according to  claim 2 , wherein the catalytic reformer operates in accordance with catalytically supported partial oxidation.  
   
   
       6 . A process according to  claim 2 , wherein the reformer is an Auto-Thermal Reactor (ATR).  
   
   
       7 . A process according to  claim 1 , wherein the fuel cell is a solid oxide fuel cell (SOFC=Solid Oxide Fuel Cell).  
   
   
       8 . A process according to  claim 1 , wherein the fuel cell is a molten carbonate fuel cell (MCFC=Molten Carbonate Fuel Cell).  
   
   
       9 . A process according to  claim 7 , further comprising converting the fuel of the thermal engine directly in the fuel cell as an internal reformation and using the anode exhaust gas as a reducing agent.  
   
   
       10 . A process according to  claim 1 , further comprising converting nitrogen oxides in a catalyst containing noble metals at temperatures of between 90 and 200° C. in the converters.  
   
   
       11 . A process according to  claim 1 , further comprising converting in an SCR (Selective Catalytic Reduction) catalytic converter in a temperature range of from 350 to 600° C. in the converters.  
   
   
       12 . A process according to  claim 1 , further comprising converting in two of the catalytic converters connected one after the other in series, wherein the converters comprise an SCR catalytic converter and a low-temperature noble metal catalyst, wherein each of the catalytic converters finds a flue gas temperature which is most suitable for it, and each converter is supplied with the reducing agent stream independently of the other one.  
   
   
       13 . A process according to  claim 1 , wherein the thermal engine is a gas turbine for mobile use, the method further comprising injecting the reducing agent into the turbine, wherein the turbine includes parts selected from the group consisting of moving blades, guide blades and inner casing parts and the selected parts are shaped as catalytic surfaces.  
   
   
       14 . A process according to  claim 1 , wherein the gas turbine is for stationary use, and the reducing agent is injected into the turbine, wherein turbine includes parts selected from the group consisting of moving blades, guide blades and inner casing parts and the selected parts are shaped as catalytic surfaces and the process further comprising converting by an SCR catalytic converter in a flue gas stream downstream of the turbine.  
   
   
       15 . A process according to  claim 1 , wherein the gas turbine is for mobile use as a turboprop engine in an airplane propulsion system, and that the reducing agent is injected into the turbine, wherein turbine includes parts selected from the group consisting of moving blades, guide blades and inner casing parts and the selected parts are shaped as catalytic surfaces and the process further comprising converting by an SCR catalytic converter in a flue gas stream downstream of turbine.  
   
   
       16 . A process according to  claim 1 , further comprising achieving a cooling effect in the turbo set via an endothermic oxidation-reduction reaction.  
   
   
       17 . A process according to  claim 13 , wherein the fuel cell produces electrical power and the process further comprising using the electrical power of the fuel cell for electric heating of the catalytic converters.  
   
   
       18 . A device for catalytic Nox reduction in oxygen-containing exhaust gases of a thermal engine, comprising at least one reduction catalytic converter provided in an exhaust pipe of a thermal engine, a reducing-agent feed line running into the reduction catalytic converter, a fuel cell into which a fuel pipe runs and operable to supply fuel from a fuel tank into the thermal engine and the reducing-agent feed line originates from the fuel cell.  
   
   
       19 . The device according to  claim 18 , further comprising a reformer and the fuel cell are provided in series.  
   
   
       20 . A device according to  claim 18 , further comprising a metering valve in the reducing agent pipe, which the metering valve being actuated via a metering control system which is linked to an electronic engine management.  
   
   
       21 . A device according to  claim 19 , further comprising for ensuring the optimum operating temperature of the catalytic converter, at least one of the reduction catalytic converter the reformer and the fuel cell is thermally integrated in a casing via heat exchangers, or heat-conducting connections or structural integration.  
   
   
       22 . A device according to  claim 18 , wherein the catalytic converter is a noble metal catalyst.  
   
   
       23 . A device according to  claim 18 , wherein the converters include a high-temperature catalytic converter and a low-temperature catalytic converter connected in series, and each of the catalytic converters is flow-connected to at least one of the reformers and the fuel cell via a metering valve.  
   
   
       24 . A device according to  claim 19 , further comprising mixing valves for mixing the reducing agents from the reformer and the fuel cell.  
   
   
       25 . A device according to  claim 18 , further comprising an electronic control means operable for supplying the mass flow of the reduction gas mixture individually for each catalytic converter, the electronic controlling means comprising a solenoid valve and a controlling device for pulse-width control.  
   
   
       26 . A device according to  claim 19 , further comprising a desulfurization system arranged upstream of at least one of the reformers and the fuel cell.  
   
   
       27 . A device according to  claim 19 , further comprising a desulfurization system arranged in series in front of the branching of the fuel for at least one of the reformers and the fuel cell.  
   
   
       28 . A device according to  claim 19 , wherein the reformer is an Auto-Thermal Reformer (ATR) operating according to the catalytically supported partial oxidation.  
   
   
       29 . A device according to  claim 18 , wherein the fuel cell is a solid oxide fuel cell (SOFC) ( 9   a ) or a molten carbonate fuel cell (MCFC) ( 9   b ).