Exhaust gas reactor

Abstract

An exhaust gas reactor is disclosed which utilizes microwave energy to create a plasma whereby chemical reactions are promoted. Such reactions serve to reduce pollutant emission. The processor has a microwave-resonant cavity ( 6 ) formed either in an exhaust passage of a combustion chamber or in the combustion chamber itself, the cavity receiving in either case exhaust gases released by combustion in the chamber. Subjection of the exhaust gases to microwaves causes them to form a plasma in which chemical reactions take place.

1 - 23 . (canceled)  
   
   
       24 . An exhaust gas reactor comprising a microwave source, a microwave-resonant reactor chamber having an electrically conductive boundary, and means for coupling microwaves from the source into the reactor chamber, wherein the reactor chamber is formed as or communicates with a combustion chamber, the reactor chamber receiving in either case exhaust gases released by combustion in the combustion chamber and communicating with an outlet through which the exhaust gases pass to reach the atmosphere, the exhaust gases being consequently subject to microwave energy and being thereby converted, in an interaction zone of the processor, into a plasma whereby chemical reactions in the exhaust gas are promoted.  
   
   
       25 . An exhaust gas reactor as claimed in  claim 24  wherein the reactor chamber is defined by a metal reactor chamber wall.  
   
   
       26 . An exhaust gas reactor as claimed in  claim 24  wherein the combustion chamber is part of a combustion engine.  
   
   
       27 . An exhaust gas reactor as claimed in  claim 24  wherein the reactor chamber forms part of an internal combustion engine's exhaust manifold.  
   
   
       28 . An exhaust gas reactor as claimed in  claim 24  wherein the reactor chamber is formed by a cylinder of an internal combustion engine.  
   
   
       29 . An exhaust gas reactor as claimed in  claim 24  wherein the microwave source comprises a magnetron.  
   
   
       30 . An exhaust gas reactor as claimed in  claim 24  wherein the means for coupling microwaves from the source into the reactor chamber comprises an antenna in the reactor chamber.  
   
   
       31 . An exhaust gas reactor as claimed in  claim 24  wherein the means for coupling microwaves into the reactor chamber comprises a hollow, conductive walled waveguide communicating with the chamber.  
   
   
       32 . An exhaust gas reactor as claimed in  claim 24  comprising means for locally intensifying electrical field in the reactor chamber thereby promoting striking of a plasma discharge in the cavity.  
   
   
       33 . An exhaust gas reactor as claimed in  claim 32  wherein the means for locally intensifying electric field comprise an electrically conductive projection in the chamber.  
   
   
       34 . An exhaust gas reactor as claimed in  claim 24  wherein the microwave source comprises a modulator providing time varying microwave power.  
   
   
       35 . An exhaust gas reactor as claimed in  claim 34  wherein the microwave power is pulsed.  
   
   
       36 . An exhaust gas reactor as claimed in  claim 34  wherein the duty cycle of the time variation in microwave power is adjustable to vary average microwave power.  
   
   
       37 . An exhaust gas reactor as claimed in  claim 36  wherein the duty cycle is variable by an electronic controller receiving inputs from an associated internal combustion engine, the electronic controller serving to vary the duty cycle in dependence upon engine operating parameters.  
   
   
       38 . An exhaust gas reactor as claimed in  claim 24  in which the reactor chamber is formed by an electrically conductive wall.  
   
   
       39 . An exhaust gas reactor as claimed in  claim 24  further comprising a filter adapted and arranged to filter particulate material from the exhaust gases.  
   
   
       40 . An exhaust gas reactor as claimed in  claim 39  wherein the filter is positioned such as to be exposed to heating by the plasma.  
   
   
       41 . An exhaust gas reactor as claimed in  claim 40  wherein the filter comprises a wire mesh.  
   
   
       42 . An exhaust gas reactor as claimed in  claim 24  comprising a second chamber communicating with the outlet from the reactor chamber, the content of the second chamber being dielectrically heatable by means of microwaves.  
   
   
       43 . An exhaust gas reactor as claimed in  claim 42  wherein the second chamber contains a filter.  
   
   
       44 . An exhaust gas reactor as claimed in  claim 42  comprising means for varying the levels of microwave energy supplied to the reactor chamber and to the second chamber in operation.  
   
   
       45 . A method of processing exhaust gases comprising receiving the exhaust gases in a microwave-resonant reactor chamber having an electrically conductive boundary, out of which the exhaust gases subsequently pass to reach the atmosphere, and coupling microwaves into the reactor chamber thereby to convert the exhaust gases, in an interaction zone, into a plasma and so to promote chemical reactions in the exhaust gas.  
   
   
       46 . A method as claimed in  claim 45  comprising coupling the microwaves into the exhaust gases through a hollow conductive waveguide.