Ultra low emissions firetube boiler burner

Abstract

According to an embodiment, a fired heater includes a fuel and combustion air source configured to output fuel and combustion air into a combustion volume, the combustion volume including a combustion volume wall defining a lateral extent separate from an exterior volume. According to an embodiment, the fired heater includes a boiler heater and the combustion volume wall comprises a combustion pipe defining a lateral extent of the combustion volume, the combustion pipe being disposed to separate the combustion volume from a water and steam volume. The fired heater includes a mixing tube aligned to receive the fuel and combustion air from the fuel and combustion air source. The mixing tube may be separated from the combustion volume wall by a separation volume. The fired heater includes a bluff body flame holder aligned to receive a fuel and combustion air mixture from an outlet end of the mixing tube. The bluff body flame holder may be configured to hold a combustion reaction for heating a combustion volume wall. The combustion volume wall may include a combustion pipe. The combustion pipe may be configured to heat the water in the water and steam volume.

1 . A combustion system, comprising:
 a frame configured to be suspended from an inner surface of a combustion volume wall;   one or more refractory bluff bodies supported by the frame;   a pilot burner configured to selectively support a pilot flame for heating the one or more refractory bluff bodies; and   a secondary fuel source configured to supply secondary fuel to a combustion reaction held by the one or more refractory bluff bodies.   
     
     
         2 . The combustion system of  claim 1 , wherein the secondary fuel source is actuatable to supply the secondary fuel when the pilot burner is selected to not support the pilot flame. 
     
     
         3 . The combustion system of  claim 1 , wherein the one or more refractory bluff bodies comprise substantially combustion air-impervious solid ceramic tiles configured to prevent combustion from occurring within the ceramic tiles. 
     
     
         4 . The combustion system of  claim 1 , wherein at least a portion of the one or more refractory bluff bodies include one or more perforated flame holders. 
     
     
         5 . The combustion system of  claim 4 , wherein the perforated flame holder is a reticulated ceramic perforated flame holder. 
     
     
         6 . The combustion system of  claim 1 , wherein the frame includes a latch configured to compress the frame against the inner surface of the combustion volume wall;
 wherein the latch includes:   a moveable coupling supported at a first end of the frame;   a bushing coupled to the moveable coupling;   a lever rotatably engaged with the bushing; and   a boss supported at a second end of the frame and rotatably engaged with the lever.   
     
     
         7 . The combustion system of  claim 6 , wherein the geometry of the latch provides an over-center stable coupling of ends of the frame while in a compressed state. 
     
     
         8 . The combustion system of  claim 1 , wherein the frame is at least partly formed from at least one of: high temperature steel; stainless steel; a ceramic;
 silicon carbide; and zirconia.   
     
     
         9 . The combustion system of  claim 1 , wherein the combustion pipe is characterized by a cross sectional area; and
 wherein the frame and the one or more refractory bluff bodies subtend less than the entire cross-sectional area.   
     
     
         10 . The combustion system of  claim 1 , wherein the frame and the one or more refractory bluff bodies supported by the frame include a plurality of frames supporting respective pluralities of bluff body tiles, each frame being disposed at a different respective distance from the pilot burner of the fuel and combustion air source. 
     
     
         11 . The combustion system of  claim 1 , further comprising a mixing tube aligned to receive the secondary fuel and combustion air from a fuel and combustion air source, the mixing tube being separated from the combustion volume wall by a separation volume. 
     
     
         12 . The combustion system of  claim 11 , wherein the combustion volume wall comprises a combustion pipe in a boiler;
 wherein the refractory bluff bodies are aligned to receive a secondary fuel and combustion air mixture from the outlet end of the mixing tube, the refractory bluff bodies being configured to hold a combustion reaction for heating the combustion pipe, wherein the combustion pipe is configured to heat water in a water and steam volume.   
     
     
         13 . The combustion system of  claim 11 , wherein the fuel and combustion air source includes:
 a fuel riser extending to a tip;   a primary combustion air plenum configured to supply primary combustion air and including a wall disposed around the fuel riser and defining a primary combustion air plenum chamber; and   a variable swirler disposed to controllably cause the primary combustion air to swirl at either of two or more different rotational velocities at at least a location corresponding to the tip of the fuel riser.   
     
     
         14 . The combustion system of  claim 13 , wherein the fuel and combustion air source is operable to, in a first mode, support a pilot flame extending from an end of the primary combustion air plenum proximal to the fuel riser tip, or, in a second mode, without supporting the pilot flame, supply combustion air to a bluff body flame holder. 
     
     
         15 . The combustion system of  claim 13 , wherein a secondary fuel source includes one or more secondary fuel nozzles disposed away from an output end of the primary combustion air plenum. 
     
     
         16 . The combustion system of  claim 13 , wherein the fuel and combustion air source includes a secondary combustion air plenum configured to output secondary combustion air independently from an output of the primary combustion air. 
     
     
         17 . The combustion system of  claim 13 , wherein the wall of the primary combustion air plenum forms a tapered region at an outlet end of the primary combustion air plenum near the tip of the fuel riser. 
     
     
         18 . A fuel and air source for a burner, comprising:
 a fuel riser extending to a tip;   a primary combustion air plenum including a wall disposed around the fuel riser and defining a primary combustion air plenum chamber; and   a variable swirler disposed to controllably cause primary combustion air to swirl at either of two or more different rotational velocities at at least a location corresponding to the tip of the fuel riser.   
     
     
         19 . The fuel and air source for a burner of  claim 18 , wherein the wall of the primary combustion air plenum forms a tapered region at an outlet end of the primary combustion air plenum near the tip of the fuel riser. 
     
     
         20 . The fuel and air source fora burner of  claim 18 , wherein the fuel riser provides a fuel orifice at the tip. 
     
     
         21 . The fuel and air source for a burner of  claim 18 , wherein the fuel riser provides a fuel orifice at a primary fuel output location disposed between a base of the fuel riser and the tip of the fuel riser. 
     
     
         22 . The fuel and air source fora burner of  claim 18 , further comprising a lobe mixer disposed proximate the tip of the fuel riser. 
     
     
         23 . The fuel and air source for a burner of  claim 22 , wherein the lobe mixer is coupled to an end of the primary combustion air plenum. 
     
     
         24 . The fuel and air source for a burner of  claim 18 , wherein the variable swirler includes:
 a plurality of actuatable fixed location blades that are collectively rotatable to at least two different angles.   
     
     
         25 . The fuel and air source for a burner of  claim 18 , wherein the variable swirler includes an air duct forming a tangential primary combustion air damper. 
     
     
         26 . The fuel and air source for a burner of  claim 18 , wherein the variable swirler is disposed within the wall of the primary combustion air plenum, radial to the fuel riser. 
     
     
         27 . The fuel and air source for a burner of  claim 18 , further comprising:
 one or more secondary fuel nozzles disposed away from the output end of the primary combustion air plenum.   
     
     
         28 . The fuel and air source fora burner of  claim 18 , further comprising:
 a secondary combustion air plenum configured to output secondary combustion air independently from the output of the primary combustion air.   
     
     
         29 . The fuel and air source fora burner of  claim 18 , further comprising:
 a bell mouth disposed to receive air and fuel from an air and fuel source and an educted flue gas flow;   a mixing tube operatively coupled to the bell mouth, the mixing tube being operable to intermittently mix the air and the fuel, and receive heat from an intermittently supported flame; and   a flame holder disposed to intermittently receive heat from the flame and receive the fuel and air flow, and to respectively increase in temperature and hold a second flame.   
     
     
         30 . The fuel and air source for a burner of  claim 29 , wherein the flame holder includes at least one bluff body flame holder. 
     
     
         31 . A method of operating a boiler heater, comprising:
 outputting fuel and combustion air from a fuel and combustion air source into a combustion pipe defining a lateral extent of a combustion volume, the combustion pipe being disposed to separate the combustion volume from a water and steam volume;   receiving, from the fuel and combustion air source, the fuel and the combustion air in a mixing tube aligned to receive the fuel and the combustion air from the fuel and combustion air source, the mixing tube being separated from the combustion pipe by a separation volume;   receiving, in a bluff body flame holder, a mixture of the fuel and the combustion air from an outlet end of the mixing tube;   holding a combustion reaction of the fuel and the combustion air with the bluff body flame holder;   heating the combustion pipe with the combustion reaction; and   heating water in the water and steam volume with the combustion pipe.   
     
     
         32 . A method of operating a combustion system, comprising:
 suspending a frame from an inner surface of a combustion pipe;   supporting one or more refractory bluff bodies with the frame;   selectively supporting a pilot flame with a pilot burner;   heating the one or more refractory bluff bodies with the pilot flame when the pilot flame is present;   supplying secondary fuel to the one or more refractory bluff bodies with a secondary fuel source; and   holding a combustion reaction of the secondary fuel and combustion air with the one or more refractory bluff bodies.   
     
     
         33 . A method of operating a fuel and air source for a burner, comprising:
 outputting a primary fuel from a fuel riser extending to a tip;   providing primary combustion air to a primary combustion air plenum chamber defined by a wall of the primary combustion air plenum disposed around the fuel riser and defining the primary combustion air plenum chamber; and   swirling, with a variable swirler, the primary combustion air at either of two or more different rotational velocities at at least a location corresponding to the tip of the fuel riser.   
     
     
         34 . The method of  claim 33 , wherein the wall of the primary combustion air plenum forms a tapered region at an outlet end of the primary combustion air plenum near the tip of the fuel riser.