Catalytic gas heater screen system

Abstract

A system for oxidation of carbon monoxide produced from gas log sets used in a vent free mode in a wood burning fireplace or fireplace insert. In the system a vent chamber is placed in the top of the combustion chamber. The vent chamber has three sides, a ceiling and a floor the front of the chamber being open and venting outside of the firebox. The vent chamber is positioned in the top of the fireplace combustion chamber. The floor of the vent chamber has a hole cut into it and a low shape profile, low pressure drop catalytic screen placed in the hole so that the exhaust can pass through the catalyst into the chamber and then vent to the room. A curtain may be placed below the chamber vent and in front of the catalyst to act as a baffle or dam to restrict the flow of rising hot exhaust and redirecting it through the catalyst.

The invention claimed is:  
     
         1 . A system to provide for oxidation of carbon monoxide produced from gas log sets used in a vent free mode in a wood burning fireplace or fireplace insert comprising a vent chamber positioned at the top of a combustion chamber, said vent chamber having three sides, a top, a floor having an opening therein for gaseous communication with said combustion chamber, an open front to vent outside of the combustion chamber having a mouth, a catalytic structure is positioned in the opening in a frame so that a portion of exhaust from burning within the combustion chamber passes through the catalytic structure into the vent chamber.  
     
     
         2 . The system according  claim 1  wherein the catalytic structure comprises at least one screen.  
     
     
         3 . The system according to  claim 2  wherein the screen has more than 30% open area.  
     
     
         4 . The system according to  claim 3  wherein the screen has more than 6 meshes per square inch to less than 600 meshes per square inch and open area in the range of 35 to 75%.  
     
     
         5 . The system according to  claim 2  wherein catalytic structure comprises more than one screen.  
     
     
         6 . The system according to  claim 2  wherein said screen is coated with a high surface area ceramic chosen from aluminum oxide, cerium oxide, titanium oxide, zirconium oxide or mixtures thereof and a catalytic component of platinum, palladium, cobalt or mixtures thereof.  
     
     
         7 . The system according to  claim 2  wherein said screen is coated with a catalytic coating is composed of a high surface area oxide coating and a noble metal catalytic component.  
     
     
         8 . The system according to  claim 7  wherein the noble metal comprises Pt.  
     
     
         9  The system according to  claim 1  wherein said curtain extends below said frame across said mouth.  
     
     
         10 . The system according to  claim 9  wherein said curtain is porous.  
     
     
         11 . The system according to  claim 9  wherein said curtain is non porous.  
     
     
         12 . The system according to  claim 10  or  11  wherein said curtain is metallic.