Natural draft low swirl burner

Abstract

A new design for a low swirl burner is disclosed in which natural draft rather than a motorized pump is used to move a fuel-air mixture through the burner. This new design enables the burn off of gas at refineries in an environment where electric motors cannot be used because of the potential for sparks, which could trigger explosions. Additional modifications to the burner, including the introduction of flue gas to the burner allows for the reduction of NOx gas to meet current emission control targets, without the need for further post combustion emission control systems.

We claim: 
     
         1 . A natural draft Low Swirl Burner (LSB) including an air entrainment system driven by one or more jets of fuel, wherein the fuel is introduced in such a way as to create a well-mixed fuel-air blend and establish a flow pattern having the appropriate swirl number for the low swirl burner into which it is introduced. 
     
     
         2 . The natural draft Low Swirl Burner of  claim 1  wherein the appropriate swirl number is obtained using a suitable mechanical swirler. 
     
     
         3 . The natural draft Low Swirl Burner of  claim 1  wherein the appropriate swirl number is obtained by incorporating one or more fuel jets oriented axially and radially in such manner as to establish a suitable swirl pattern. 
     
     
         4 . The natural draft Low Swirl Burner of  claim 1  further including a venturi at the LSB inlet, whereby when a jet of fuel is directed into the venturi and a flow of air induced and mixed with the fuel. 
     
     
         5 . The natural draft Low Swirl Burner of  claim 4  wherein re-circulated flue gas is injected into the venturi of the LSB to mix with air and fuel.