Flare stack with perforated flame holder

Abstract

A flare stack burner includes a fuel stack housing in which a fuel nozzle and a perforated flame holder are positioned. The fuel nozzle is configured to emit a fuel stream toward the flame holder.

What is claimed is: 
     
         1 . A device, comprising:
 a housing including an inlet configured to be coupled to a waste fuel supply as part of a flare stack, and an outlet configured to release products of combustion to the atmosphere;   a perforated flame holder positioned inside the housing and having a first face, a second face lying opposite the first face, and a plurality of perforations extending through the perforated flame holder between the first and second faces; and   a nozzle configured to receive a flow of fuel from the inlet, and to emit a fuel stream toward the first face of the perforated flame holder.   
     
     
         2 . The device of  claim 1 , wherein the housing is configured to be freestanding, supported only by a coupling at the inlet. 
     
     
         3 . The device of  claim 1 , wherein the housing is configured to be coupled to the flare stack and to be supported thereby. 
     
     
         4 . The device of  claim 1 , wherein the nozzle is coupled to receive the flow of fuel via a fuel line extending through the inlet into the housing. 
     
     
         5 . The device of  claim 1 , wherein the nozzle is one of a plurality of nozzles, each configured to receive a flow of fuel from the inlet, and to emit a fuel stream toward a respective portion of the first face of the perforated flame holder. 
     
     
         6 . The device of  claim 5 , wherein each of the plurality of nozzles is coupled to receive the respective flow of fuel via a common fuel line extending through the inlet into the housing. 
     
     
         7 . The device of  claim 6 , further comprising a plurality of fuel valves operatively coupled between the common fuel line and a respective one of the plurality of nozzles and configured to independently control operation of the respective nozzle. 
     
     
         8 . The device of  claim 1 , further comprising:
 a start-up burner positioned within the housing; and   a retrofit burner positioned within the housing, the retrofit burner including the perforated flame holder and the nozzle.   
     
     
         9 . The device of  claim 8 , wherein the start-up burner includes a plurality of burner nozzles arranged in an array within the housing. 
     
     
         10 . The device of  claim 9 , wherein the nozzle is one of a plurality of nozzles of the retrofit burner, interleaved among the array of burner nozzles of the start-up burner. 
     
     
         11 . The device of  claim 10 , wherein the start-up burner is a fin-tube burner, and wherein the plurality of nozzles of the retrofit burner is interleaved among fin plates of the fin-tube burner. 
     
     
         12 . The device of  claim 8 , wherein the start-up burner is configured to support a flame between the start-up burner and the perforated flame holder of the retrofit burner. 
     
     
         13 . The device of  claim 1 , wherein the nozzle includes an aperture having a size that is variable. 
     
     
         14 . The device of  claim 13 , wherein the nozzle is configured to regulate a velocity of the fuel stream. 
     
     
         15 . The device of  claim 13 , further comprising an actuator operatively coupled to the nozzle and configured to control the size of the aperture. 
     
     
         16 . The device of  claim 13 , wherein the nozzle includes a nozzle outlet and a control element, the control element being positioned to occlude some portion of the nozzle outlet, and wherein movement of the control element varies a degree to which the nozzle outlet is occluded by the control element. 
     
     
         17 . A method, comprising:
 outputting a waste gas and supplemental fuel sufficient to raise a heating value of the waste gas plus supplemental fuel to about  100  BTU per cubic foot or less toward a perforated flame holder; and   combusting the waste gas and supplemental fuel substantially within a plurality of perforations extending through the perforated flame holder.   
     
     
         18 . The method of  claim 17 , wherein the combusting waste gas comprises emitting a fuel stream that includes the waste gas from a nozzle positioned within a flare stack and toward the perforated flame holder. 
     
     
         19 . The method of  claim 18 , further comprising, prior to performing the combusting waste gas substantially within a plurality of perforations extending through the perforated flame holder, preheating the perforated flame holder by operating a start-up burner positioned within the flare stack. 
     
     
         20 . The method of  claim 19 , comprising, after performing the preheating the flame holder:
 shutting off a flow of fuel to the start-up burner; and   introducing a flow of fuel to the nozzle.   
     
     
         21 . The method of  claim 18 , wherein the emitting a fuel stream from the nozzle positioned within the flare stack is comprised by emitting a fuel stream from each of a plurality of nozzles positioned within the flare stack, each toward a respective portion of the perforated flame holder. 
     
     
         22 . The method of  claim 21 , wherein the emitting a fuel stream from each of the plurality of nozzles positioned within the flare stack comprises selecting a number of the plurality of nozzles based upon a volume of waste gas to be combusted. 
     
     
         23 . The method of  claim 22 , wherein the selecting a number of the plurality of nozzles based upon the volume of waste gas to be combusted comprises varying the number of the plurality of nozzles in response to changes in the volume of waste gas. 
     
     
         24 . The method of  claim 18 , comprising varying an aperture size of the nozzle in response to changes in a volume of waste gas to be combusted. 
     
     
         25 . The method of  claim 24 , wherein the varying an aperture size of the nozzle comprises varying a degree of occlusion of an outlet of the nozzle. 
     
     
         26 . The method of  claim 17 , wherein the perforated flame holder is positioned within a flare stack; and
 further comprising venting products of the combustion to the atmosphere.