Furnace including perforated and bluff body flame holder for enhanced stability and turndown

Abstract

A combustion system includes a perforated flame holder and a plurality of bluff body members positioned between the perforated flame holder and a fuel source. The fuel source outputs a fuel stream through gaps between the bluff body members toward the perforated flame holder. The perforated flame holder and the bluff body members collectively hold a combustion reaction supported by the fuel stream.

What is claimed is: 
     
         1 . A combustion system, comprising:
 a perforated flame holder positioned in a furnace volume;   an oxidant source configured to introduce an oxidant into the furnace volume;   a fuel source configured to output a fuel stream including a fuel toward the perforated flame holder; and   a plurality of bluff body members positioned between the fuel source and the perforated flame holder, the bluff body members being separated from each other by gaps selected to allow the fuel stream to pass through the gaps toward the perforated flame holder, the plurality of bluff body members and the perforated flame holder being configured to collectively support a combustion reaction of the fuel and the oxidant within the perforated flame holder.   
     
     
         2 . The combustion system of  claim 1 , wherein the bluff body members and the perforated flame holder are configured to support the combustion reaction within the perforated flame holder and in a space between the bluff body members and the perforated flame holder. 
     
     
         3 . The combustion system of  claim 1 , further comprising a support structure holding the bluff body members. 
     
     
         4 . The combustion system of  claim 3 , wherein the support structure is configured to support the perforated flame holder. 
     
     
         5 . The combustion system of  claim 4 , wherein the plurality of bluff body members includes:
 a first row of bluff body members; and   a second row of bluff body members positioned between the first row of bluff body members and the perforated flame holder.   
     
     
         6 . The combustion system of  claim 5 , wherein the bluff body members of the first row extend in a first direction and the bluff body members of the second row extend in a second direction transverse to the first direction. 
     
     
         7 . The combustion system of  claim 5 , wherein the bluff body members of the first row extend parallel to the bluff body members of the second row. 
     
     
         8 . The combustion system of  claim 7 , wherein the bluff body members of the second row are aligned with the gaps between the bluff body members of the first row. 
     
     
         9 . The combustion system of  claim 7 , wherein the bluff body members of the second row are aligned with the bluff body members of the first row. 
     
     
         10 . The combustion system of  claim 5 , wherein the plurality of bluff body members includes a third row of bluff body members positioned between the second row of bluff body members and the perforated flame holder. 
     
     
         11 . The combustion system of  claim 3 , wherein the support structure includes:
 a plurality of support legs supporting the perforated flame holder and the bluff body members above the fuel source; and   a bracket coupled to one or more of the support legs and configured to hold the bluff body members.   
     
     
         12 . The combustion system of  claim 11 , wherein the bracket includes a plurality of apertures configured to support end portions of the bluff body members. 
     
     
         13 . The combustion system of  claim 11 , wherein the support structure includes a ceramic material. 
     
     
         14 . The combustion system of  claim 13 , wherein the support structure is entirely ceramic. 
     
     
         15 . The combustion system of  claim 1 , wherein the bluff body members have a circular cross-section. 
     
     
         16 . The combustion system of  claim 1 , wherein the bluff body members have an elliptical cross-section. 
     
     
         17 . The combustion system of  claim 1 , wherein the bluff body members have an ovular cross-section. 
     
     
         18 . The combustion system of  claim 1 , wherein characteristics of the fuel stream and the bluff body members are configured to introduce a vortex motion into the fuel stream downstream from the bluff body members. 
     
     
         19 . The combustion system of  claim 1 , wherein characteristics of the fuel stream and the bluff body members are configured to introduce a turbulent wake downstream from the bluff body members. 
     
     
         20 . The combustion system of  claim 1 , wherein the perforated flame holder is a reticulated ceramic perforated flame holder. 
     
     
         21 . The combustion system of  claim 20 , wherein the perforated flame holder includes a plurality of reticulated fibers. 
     
     
         22 . The combustion system of  claim 21 , wherein the perforated flame holder includes zirconia. 
     
     
         23 . The combustion system of  claim 21 , wherein the perforated flame holder includes alumina silicate. 
     
     
         24 . The combustion system of  claim 21 , wherein the perforated flame holder includes silicon carbide. 
     
     
         25 . The combustion system of  claim 21 , wherein the reticulated fibers are formed from extruded mullite. 
     
     
         26 . The combustion system of  claim 21 , wherein the reticulated fibers are formed from cordierite. 
     
     
         27 . The combustion system of  claim 21 , wherein the perforated flame holder is configured to support a combustion reaction of the fuel and the oxidant upstream, downstream, and within the perforated flame holder. 
     
     
         28 . The combustion system of  claim 21 , wherein the perforated flame holder has 3 to 30 pores per linear inch of surface area. 
     
     
         29 . The combustion system of  claim 21 , the perforated flame holder includes a plurality of perforations formed as passages between the reticulated fibers. 
     
     
         30 . The combustion system of  claim 29 , wherein the perforations are branching perforations. 
     
     
         31 . The combustion system of  claim 29 , wherein the perforated flame holder includes:
 an input face proximal to the fuel source; and   an output face distal to the fuel source.   
     
     
         32 . The combustion system of  claim 31 , wherein the perforations extend between the input face and the output face. 
     
     
         33 . The combustion system of  claim 31 , wherein the input face corresponds to an extent of the reticulated fibers proximal to the fuel source. 
     
     
         34 . The combustion system of  claim 33 , wherein the output face corresponds to an extent of the reticulated fibers distal to the fuel source. 
     
     
         35 . The combustion system of  claim 31 , wherein the perforated flame holder is configured to support at least a portion of the combustion reaction within the perforated flame holder between the input face and the output face. 
     
     
         36 . The combustion system of  claim 1 , wherein one or more of the gaps is between 0.25 inch and 3 inches. 
     
     
         37 . The combustion system of  claim 36 , wherein one or more of the gaps is about equal to a thickness of one of the bluff body members. 
     
     
         38 . The combustion system of  claim 37 , wherein the thickness of the one of the bluff body members is about 0.25 inches. 
     
     
         39 . The combustion system of  claim 1 , wherein the fuel source includes a fuel nozzle. 
     
     
         40 . A method, comprising:
 supporting a perforated flame holder in a furnace volume;   supporting a plurality of bluff body members in the furnace volume between the perforated flame holder and a fuel source;   introducing an oxidant into the furnace volume;   passing a fuel stream including a fuel from the fuel source through gaps between the bluff body members towards the perforated flame holder; and   supporting a combustion reaction of the fuel and the oxidant within the perforated flame holder.   
     
     
         41 . The method of  claim 40 , further comprising supporting the combustion reaction of the fuel and the oxidant in a space between the perforated flame holder and the bluff body members. 
     
     
         42 . The method of  claim 40 , further comprising introducing a vortex motion into the fuel stream with the bluff body members. 
     
     
         43 . The method of  claim 40 , further comprising introducing a turbulent motion into the fuel stream with the bluff body members. 
     
     
         44 . The method of  claim 43 , further comprising entraining the oxidant in the fuel stream. 
     
     
         45 . The method of  claim 44 , further comprising enhancing entrainment of the oxidant by introducing a vortex motion into the fuel stream with the bluff body members. 
     
     
         46 . The method of  claim 45 , further comprising enhancing entrainment of the oxidant by introducing a turbulent wake in the fuel stream with the bluff body members. 
     
     
         47 . The method of  claim 40 , wherein the perforated flame holder is a reticulated ceramic perforated flame holder. 
     
     
         48 . The method of  claim 47 , wherein the perforated flame holder includes a plurality of reticulated fibers. 
     
     
         49 . A combustion system, comprising:
 a perforated flame holder positioned in a furnace volume;   an oxidant source configured to introduce an oxidant into the furnace volume;   a fuel source configured to output a fuel stream including a fuel toward the perforated flame holder; and   a plurality of bluff body members positioned between the fuel source and the perforated flame holder and configured to perturb the fuel stream as the fuel stream passes between the bluff body members towards the perforated flame holder, the perforated flame holder being configured to collectively support a combustion reaction of the fuel and the oxidant within the perforated flame holder.   
     
     
         50 . The combustion system of  claim 49 , further comprising a support structure supporting the bluff body members within the furnace volume. 
     
     
         51 . The combustion system of  claim 50 , wherein the support structure supports the perforated flame holder within the furnace volume. 
     
     
         52 . The combustion system of  claim 49 , wherein the bluff body members and the perforated flame holder are configured to support the combustion reaction within the perforated flame holder and in a space between the bluff body members and the perforated flame holder. 
     
     
         53 . The combustion system of  claim 49 , wherein characteristics of the fuel stream and the bluff body members are configured to perturb the fuel stream by introducing a vortex motion into the fuel stream downstream from the bluff body members. 
     
     
         54 . The combustion system of  claim 49 , wherein characteristics of the fuel stream and the bluff body members are configured to perturb the fuel stream by introducing a turbulent wake downstream from the bluff body members.