Apparatus and method for controlled combustion of gaseous pollutants

Abstract

The present invention relates to systems and methods for controlled combustion of gaseous pollutants while reducing and removing deposition of unwanted reaction products from within the treatment systems. The systems employ a two-stage thermal reactor having an upper thermal reactor including at least one inlet for mixing a gaseous waste stream with oxidants and combustible fuels for thermal combustion within the upper thermal reactor. The upper thermal reactor further includes a double wall structure having an outer exterior wall and an interior porous wall that defines an interior space for holding a fluid and ejecting same, in a pulsating mode, through the interior porous wall into the upper thermal reactor to reduce deposition of the reaction products on the interior of the upper reactor chamber. The two-stage thermal reactor further includes a lower reactor chamber for flowing reaction products formed in the upper thermal reactor through a water vortex that provides a water overflow along the interior of the lower reactor chamber thereby reducing deposition of unwanted products on the interior surface of the lower reactor.

1 . A two-stage reactor for removing pollutants from gaseous streams, the two-stage reactor comprising:
 a) an upper thermal reaction chamber comprising:
 i) an outer exterior wall; 
 ii) an interior porous wall, wherein the interior porous wall defines a central combustion chamber, and wherein the interior porous wall is positioned from the outer exterior wall a sufficient distance to define an interior space; 
 iii) at least one waste gas inlet in fluid communication with the central combustion chamber for introducing a gaseous waste stream therein; 
 iv) thermal means for combusting the gaseous waste stream, thereby forming reaction products; 
 v) means for introducing a fluid under pulsing conditions into the interior space, wherein the interior porous wall provides for transference of the fluid from the interior space into the central combustion chamber at a sufficient force to reduce deposition of reaction products on the interior porous wall; 
   b) a lower reaction chamber comprising:
 i) a gas flow chamber in fluid communication with the central combustion chamber comprising an inlet and outlet for passing the gaseous waste stream and reaction products therethrough; 
 ii) at least one oxidant inlet positioned to introduce an oxidant to the gas stream flow chamber; and 
 iii) a liquid vortex positioned near the inlet of the gas flow chamber, wherein the liquid vortex comprises means for generating a downwardly flowing liquid film on interior surfaces of the gas stream flow chamber thereby reducing deposition and accumulation of particulate solids thereon. 
   
   
   
       2 . The two-stage reactor according to  claim 1 , wherein the interior space positioned between the outer exterior wall and the interior porous wall is an interior annular space. 
   
   
       3 . The two-stage reactor according to  claim 2 , wherein the fluid introduced into the interior annular space is pressurized. 
   
   
       4 . The two-stage reactor according to  claim 1 , wherein the fluid under pulsating conditions is selected from water, air, clean dry air, and clean enriched air. 
   
   
       5 . The two-stage reactor according to  claim 4 , wherein the fluid is water. 
   
   
       6 . The two-stage reactor according to  claim 2 , wherein the fluid is injected into the central combustion chamber under periodic pulsing. 
   
   
       7 . The two-stage reactor according to  claim 1 , wherein the pulsing conditions comprises a pulsation duration of from about 20 ms to 100 ms. 
   
   
       8 . The two-stage reactor according to  claim 1 , further comprising at least one additional gas inlet for introducing a combustible fuel or an oxidant for mixing with the gaseous waste stream. 
   
   
       9 . The two-stage reactor according to  claim 8 , wherein the combustible fuel is oxygen, propane, methane or hydrogen. 
   
   
       10 . The two-stage reactor according to  claim 1 , wherein the liquid vortex comprises:
 (i) a outer shell having a top plate, a central opening in fluid communication with the central combustion chamber;   a conical-shaped baffle within the outer shell having an inner surface and a central opening which is generally aligned with the interior surface of the gas stream flow chamber, the conical-shaped baffle generally concentrically aligned with the inner surface of the outer shell to form a concentric chamber; and   (ii) a liquid inlet arranged to tangentially introduce liquid into the concentric chamber, thereby filling the concentric chamber with liquid to create a swirling motion, causing the liquid to rise and overflow the conical-shaped baffle to form a sheet of fluid on the inner surface of the conical-shaped baffle that flows downwardly onto the interior surface of the gas stream flow chamber.   
   
   
       11 . The two-stage reactor according to  claim 10 , wherein the sheet of fluid on the inner surface of the conical-shaped baffle inhibits contact of an entering gas stream with the interior surface of the gas stream flow chamber thereby resisting deposition of reaction products thereon. 
   
   
       12 . The two-stage reactor according to  claim 1 , wherein the interior porous wall is fabricated of a material comprising sintered ceramic, sintered metal, porous metal material or a porous polymeric material. 
   
   
       13 . The two-stage reactor according to  claim 12 , wherein the interior porous wall comprises pores uniformly distributed in the porous material. 
   
   
       14 . The two-stage reactor according to  claim 1 , wherein the outer exterior wall and the interior porous wall are separated a sufficient distance to provide an annular space and for distributing a pressured gas for passage through the interior porous wall. 
   
   
       15 . The two-stage reactor according to  claim 14 , wherein the interior porous wall comprises a plurality of apertures for passage of a pressurized gas through the interior porous wall into the central combustion chamber. 
   
   
       16 . The two-stage reactor according to  claim 2 , wherein the fluid is compressed to a suitable pressure to facilitate pulsating ejection of the fluid with a force sufficient to reduce particle deposition on the inner surface of the central combustion chamber. 
   
   
       17 . The two-stage reactor according to  claim 16 , wherein the pressure is from about 60 psig to about 100 psig. 
   
   
       18 . The two-stage reactor according to  claim 15 , wherein the plurality of apertures comprises conical shaped protuberances. 
   
   
       19 . An abatement system for controlled combustion of gaseous pollutants in a gaseous waste stream, the system comprising:
 a) an upper thermal reaction chamber comprising:
 i) an outer exterior wall; 
 ii) an interior porous wall, wherein the interior porous wall defines a central combustion chamber and wherein the interior porous wall is positioned from the outer exterior wall a sufficient distance to define an interior annular space; 
 iii) means for introducing a fluid in a pulsating mode to the interior annular space; 
 vi) thermal means for combusting the gaseous waste stream, thereby forming reaction products; 
 v) at least one waste gas inlet for conducting the gaseous waste stream into the upper thermal reactor, the waste gas inlet comprising a conduit terminating with a portion of the conduit within the central combustion chamber wherein the portion of the conduit is located within a tube which projects beyond the end of the conduit to define a chamber within the tube for flame formation, the tube having an open end communicating with the central combustion chamber; 
   b) a lower reaction chamber comprising;
 i) a gas flow chamber in fluid communication with the central combustion chamber; 
 ii) at least one oxidant inlet positioned to introduce an oxidant to the gas stream flow chamber; and 
 iii) a liquid vortex positioned between the central combustion chamber and the gas stream flow chamber, wherein the liquid vortex comprises:
 (1) a outer shell having a top plate, a central opening in fluid communication with the central combustion chamber; 
 (2) a conical-shaped baffle within the outer shell having an inner surface and a central opening which is generally aligned with the interior surface of the gas stream flow chamber, the conical-shaped baffle generally concentrically aligned with the inner surface of the outer shell to form a concentric chamber; and 
 (3) a liquid inlet arranged to tangentially introduce liquid into the concentric chamber, thereby filling the concentric chamber with liquid to create a swirling motion, causing the liquid to rise and overflow the conical-shaped baffle into the gas stream flow chamber to form a sheet of fluid on the inner surface of the conical-shaped baffle that flows downwardly onto the interior surface of the gas stream flow chamber. 
 
   
   
   
       20 . The abatement system of  claim 19 , wherein the interior porous wall provides for transference of the fluid from the interior annular space into the central combustion chamber at a sufficient force to reduce deposition of reaction products on the interior porous wall.