Apparatus for removal of pollution from gas stream

Abstract

An improved thermal oxidizer ( 10 ) comprising a combustion chamber ( 62 ), a refractory coated mixing device ( 14 ) within a plenum ( 12 ), a burner ( 26 ) mounted outside the oxidizer ( 10 ) for ready access, and temperature sensing and control equipment ( 86 ). The oxidizer ( 10 ) uses the mixing device ( 14 ) to induce a static pressure drop between the burner ( 26 ) and the oxidizer inlet ( 16 ), and a flow passage conveys preheated gas from the plenum ( 12 ) to the burner ( 26 ). A bend in the combustion chamber ( 92 ) provides for recirculation of combustion gases for more efficient burning. The burner ( 26 ) can be a commercially available unit that can accommodate inlet temperatures of up to 1200° F., allowing efficient operation of the thermal oxidizer ( 10 ).

I claim:  
     
         1 . A thermal oxidizer for removing combustible substances from an oxygen-bearing gas stream comprising: 
 a combustion chamber containing at least one bend, whereby turbulence within the combustion chamber is improved, and whereby the flow direction of combustion gases is reversed and said combustion gases are efficiently removed from said combustion chamber and directed to a heat exchange means;    a mixing device located within a plenum so the axis of said mixing device is approximately perpendicular to the direction of gas flow into said plenum, said mixing device located at the entrance to said combustion chamber and said mixing device disposed axially with said combustion chamber, said mixing device containing a plurality of holes allowing flow of gas into said combustion chamber, whereby a static pressure difference between said plenum and said combustion chamber is created;    a burner assembly discharging into said mixing device, said burner assembly located external to the thermal oxidizer and disposed axially to said mixing device and said combustion chamber, whereby ready access to the burner assembly and its components is allowed;    a flow passage from said plenum to the air inlet of said burner, whereby said air inlet is supplied with oxygen-bearing gas from said plenum;    a combustion chamber gas temperature sensing means; and    a control means to vary the fuel flow to said burner, whereby a desired operating temperature in the combustion chamber is achieved and maintained.    
     
     
         2 . The thermal oxidizer of  claim 1 , wherein said mixing device comprises: 
 a metal duct, protected by a refractory lining, with a metal plate on one end that is also protected by a refractory lining;    a plurality of holes located in the sides of said duct, allowing the flow of gas through the wall of the duct, with at least one pair of said holes sized to form gas jets that meet near the centerline of said mixing device; and    means to protect the refractory lining from erosion, thermal stresses and cracking, whereby the operational life of the refractory is extended and consistent operation of the thermal oxidizer is maintained.    
     
     
         3 . A thermal oxidizer comprising: 
 a combustion chamber with means for changing the direction of flow of combustion chamber gases, whereby said gases are directed toward the inlet of said oxidizer;    a mixing device located within the inlet of said oxidizer, disposed axially to the inlet of said combustion chamber, with a plurality of holes located in the walls of said mixing device, whereby a difference in static pressure between said oxidizer inlet and said combustion chamber is created to induce the flow of gas to a burner and induce gas jets which enhance turbulence and mixing within said thermal oxidizer;    burner located external to the thermal oxidizer and disposed axially to said mixing device and the inlet of said combustion chamber;    a gas flow passage from the oxidizer inlet to the burner air inlet;    gas temperature sensing means; and    a control means to control the flow of fuel to said burner, whereby a desired operating temperature in the combustion chamber is achieved and maintained.