Heat treatment process with oxygen enhancement of air-fuel burners

Abstract

A furnace for treating metal parts includes a treatment atmosphere provided at an interior of the furnace; at least one burner operatively associated with the furnace for heating the treatment atmosphere to a temperature below a melting point of the metal parts; a passageway interconnecting the interior and the at least one burner, the passageway directing at least a portion of the heat treatment atmosphere exhausted from the furnace interior to the at least one burner for combustion; and a source of oxygen in fluid communication with the at least one burner for enriching combustion of the heat treatment atmosphere portion with oxygen at said burner. A related method is also provided.

What is claimed is: 
     
         1 . A furnace for treating metal parts, comprising:
 a treatment atmosphere provided at an interior of the furnace;   at least one burner operatively associated with the furnace for heating the treatment atmosphere to a temperature below a melting point of the metal parts;   a passageway interconnecting the interior and the at least one burner, the passageway directing at least a portion of the heat treatment atmosphere exhausted from the furnace interior to the at least one burner for combustion; and   a source of oxygen in fluid communication with the at least one burner for enriching combustion of the heat treatment atmosphere portion with oxygen at said burner.   
     
     
         2 . The furnace of  claim 1 , wherein the at least one burner comprises a fuel inlet, an air inlet, an exhaust inlet through which the heat treatment atmosphere portion is introduced to said burner, and a gas inlet through which the oxygen from said source of oxygen is introduced into said at least one burner. 
     
     
         3 . The furnace of  claim 2 , wherein the fuel, air, exhaust and gas inlets are separate from each other. 
     
     
         4 . The furnace of  claim 2 , wherein the gas inlet for said oxygen is positioned upstream of the burner from the fuel, air and exhaust inlets. 
     
     
         5 . The furnace of  claim 1 , wherein the at least one burner is selected from the group consisting of at least one indirect fired burner, and at least one direct fired air-fuel burner. 
     
     
         6 . A burner for treating a furnace atmosphere for metal parts, comprising: a first inlet for fuel, a second inlet for air, a third inlet for exhaust from said furnace atmosphere, and a fourth inlet for oxygen, wherein the furnace atmosphere is at a temperature below a melting point of the metal parts. 
     
     
         7 . The burner of  claim 6 , further comprising a housing having an internal space therein and at which the first-fourth inlets are in fluid communication. 
     
     
         8 . A method for treating metal parts in a furnace, comprising:
 providing the metal parts to a treatment atmosphere in the furnace;   heating the treatment atmosphere with at least one burner to a temperature below a melting point of the metal parts;   removing at least a portion of the treatment atmosphere for subsequent combustion at the at least one burner; and   enriching the subsequent combustion with oxygen at the at least one burner.   
     
     
         9 . The method of  claim 8 , further comprising providing fuel and air to said at least one burner for the subsequent combustion. 
     
     
         10 . The method of  claim 8 , wherein said treatment atmosphere is selected from the group consisting of an annealing atmosphere, a hardening atmosphere, a carburizing atmosphere, a brazing atmosphere and a sintering atmosphere. 
     
     
         11 . The method of  claim 8 , wherein the heating is with an indirect-fired burner. 
     
     
         12 . The method of  claim 8 , wherein the enriching comprises mixing the oxygen with the portion of the treatment atmosphere. 
     
     
         13 . The method of  claim 12 , wherein the mixing is at the at least one burner. 
     
     
         14 . The method of  claim 9 , wherein the fuel is selected from the group consisting of natural gas, propane, liquefied petroleum gas (LPG), oil and other fuel blends. 
     
     
         15 . The method of  claim 9 , wherein the providing comprises mixing said oxygen, fuel and air with the treatment atmosphere portion at the at least one burner.