Burners and components for use in burners

Abstract

A high excess air burner includes a housing including a generally tubular body enclosing an air chamber, a nozzle located in the air chamber and spaced radially inwardly of the generally tubular body, a fuel inlet configured to supply a variable volumetric flow rate of fuel, an air inlet configured to supply air to the air chamber, a first combustion cavity having a first inlet opening communicating with the fuel inlet for receiving the variable volumetric flow rate of fuel, a second combustion cavity having a second inlet opening communicating with the first combustion cavity for receiving the first fuel-air mixture, and a third combustion cavity having a third inlet opening communicating with the second combustion cavity for receiving the second fuel-air mixture. The burner including one or more components (e.g., nozzle, rear cover) to improve flame characteristics, such as flame stability or consistency, and/or one or more components or features to improve flame detection capability.

1 . A high excess air burner, comprising:
 a generally tubular body enclosing an air chamber;   a nozzle located in the air chamber and spaced radially inwardly of the generally tubular body, the nozzle having first and second combustion cavities;   a fuel inlet configured to supply a variable volumetric flow rate of fuel; and   an air inlet configured to supply air to the air chamber;   wherein the first combustion cavity has a first inlet opening communicating with the fuel inlet for receiving the variable volumetric flow rate of fuel, the first combustion cavity having first combustion air inlets communicating with the air chamber so that fuel is mixed with combustion air to form a first fuel-air mixture in the first combustion cavity;   wherein the second combustion cavity has a second inlet opening communicating with the first combustion cavity for receiving the first fuel-air mixture, the second combustion cavity having a sidewall that converges radially inwardly in a downstream direction, and the second combustion cavity having second combustion air inlets communicating with the air chamber so that the first fuel-air mixture is mixed with additional combustion air to form a second fuel-air mixture in the second combustion cavity, wherein the second combustion air inlets extend through a side wall of the nozzle at an oblique angle to a central longitudinal axis of the nozzle, and wherein an outer surface of the nozzle at a radially-outermost end of each of the second combustion air inlets is perpendicular to central axes of the second combustion air inlets.   
     
     
         2 . The high excess air burner of  claim 1  wherein each of the first combustion air inlets has the same diameter. 
     
     
         3 . The high excess air burner of  claim 1  wherein a largest one of the first combustion air inlets has a first diameter and a smallest one of the first combustion air inlets has a second diameter, wherein the first diameter is at least two times the second diameter. 
     
     
         4 . The high excess air burner of  claim 1  wherein a largest one of the first combustion air inlets has a first diameter and a smallest one of the first combustion air inlets has a second diameter, wherein the first diameter is four times the second diameter. 
     
     
         5 . The high excess air burner of  claim 1  wherein each of the second combustion air inlets has the same diameter. 
     
     
         6 . The high excess air burner of  claim 1  wherein a largest one of the second combustion air inlets has a first diameter and a smallest one of the second combustion air inlets has a second diameter, wherein the first diameter is at least two times the second diameter. 
     
     
         7 . The high excess air burner of  claim 1  wherein a largest one of the second combustion air inlets has a first diameter and a smallest one of the second combustion air inlets has a second diameter, wherein the first diameter is four times the second diameter. 
     
     
         8 . The high excess air burner of  claim 1  wherein the oblique angle at which the second combustion air inlets extend is greater than 20 degrees and less than 25 degrees. 
     
     
         9 . The high excess air burner of  claim 1  wherein the outer surface of the nozzle has a generally stepped cylindrical shape. 
     
     
         10 . The high excess air burner of  claim 1  wherein an upstream end of a portion of the outer surface of the nozzle that surrounds the second combustion cavity includes a circumferential ridge and the second combustion air inlets extend through the circumferential ridge. 
     
     
         11 . The high excess air burner of  claim 1  wherein a flow of air between an inner surface of the generally tubular body and the nozzle flowing in a direction parallel to the central longitudinal axis of the nozzle is impeded by projecting portions of the outer surface of the nozzle located in an intermediate portion of the nozzle between opposing ends of the nozzle. 
     
     
         12 . A high excess air burner, comprising:
 a generally tubular body enclosing an air chamber;   a nozzle located in the air chamber and spaced radially inwardly of the generally tubular body;   a fuel inlet configured to supply a variable volumetric flow rate of fuel;   an air inlet configured to supply air to the air chamber;   a first combustion cavity having a first inlet opening communicating with the fuel inlet for receiving the variable volumetric flow rate of fuel, the first combustion cavity having first combustion air inlets communicating with the air chamber so that fuel is mixed with combustion air to form a first fuel-air mixture in the first combustion cavity;   a second combustion cavity having a second inlet opening communicating with the first combustion cavity for receiving the first fuel-air mixture, the second combustion cavity having a sidewall that converges radially inwardly in a downstream direction, and the second combustion cavity having second combustion air inlets communicating with the air chamber so that the first fuel-air mixture is mixed with additional combustion air to form a second fuel-air mixture in the second combustion cavity; and   a third combustion cavity having a third inlet opening communicating with the second combustion cavity for receiving the second fuel-air mixture, the third combustion cavity having third combustion air inlets communicating with the air chamber so that the second fuel-air mixture is mixed with supplemental combustion air to form a third fuel-air mixture in the third combustion cavity, wherein the third combustion air inlets extend through a side wall of the nozzle at an oblique angle to a central longitudinal axis of the nozzle, and wherein an outer surface of the nozzle at a radially-outermost end of each of the third combustion air inlets is perpendicular to central axes of the third combustion air inlets.   
     
     
         13 . The high excess air burner of  claim 12  wherein the oblique angle is greater than 40 degrees and less than 50 degrees. 
     
     
         14 . The high excess air burner of  claim 13  wherein the second combustion air inlets extend through the side wall of the nozzle at a shallow angle to the central longitudinal axis of the nozzle, and wherein an outer surface of the nozzle at a radially-outermost end of each of the second combustion air inlets is perpendicular to central axes of the second combustion air inlets. 
     
     
         15 . The high excess air burner of  claim 14  wherein the shallow angle is less than the oblique angle. 
     
     
         16 . The high excess air burner of  claim 15  wherein the shallow angle is greater than 20 degrees and less than 25 degrees. 
     
     
         17 . The high excess air burner of  claim 12  wherein the outer surface of the nozzle has a generally stepped cylindrical shape. 
     
     
         18 . The high excess air burner of  claim 17  wherein an upstream portion of the outer surface of the nozzle that surrounds the second combustion cavity has a smaller diameter than a downstream portion of the outer surface of the nozzle that surrounds the third combustion cavity. 
     
     
         19 . The high excess air burner of  claim 12  wherein an upstream end of a portion of the outer surface of the nozzle that surrounds the third combustion cavity includes a circumferential ridge and the third combustion air inlets extend through the circumferential ridge. 
     
     
         20 . The high excess air burner of  claim 12 , wherein a flow of air between an inner surface of the generally tubular body and the nozzle flowing in a direction parallel to the central longitudinal axis of the nozzle is impeded by projecting portions of the outer surface of the nozzle located in an intermediate portion of the nozzle between opposing ends of the nozzle. 
     
     
         21 . A high excess air burner, comprising:
 a housing including a generally tubular body enclosing an air chamber, and including an air inlet with an air inlet axis oriented perpendicular to a longitudinal axis of the high excess air burner;   a nozzle located in the air chamber and spaced radially inwardly of the generally tubular body;   a rear cover coupled to the generally tubular body and to the nozzle, where the rear cover encloses an upstream end of the air chamber, and wherein the rear cover is configured to be coupled to the housing in incremental rotational orientations;   a fuel inlet configured to supply a variable volumetric flow rate of fuel;   an air inlet configured to supply air to the air chamber;   a first combustion cavity provided within the rear cover, the first combustion cavity having a first inlet opening communicating with the fuel inlet for receiving the variable volumetric flow rate of fuel, the first combustion cavity having first combustion air inlets communicating with the air chamber so that fuel is mixed with combustion air to form a first fuel-air mixture in the first combustion cavity, and wherein the first combustion air inlets extend at oblique angles to the air inlet axis of the air inlet of the housing; and   at least a second combustion cavity having a second inlet opening communicating with the first combustion cavity for receiving the first fuel-air mixture, and the second combustion cavity having second combustion air inlets communicating with the air chamber so that the first fuel-air mixture is mixed with additional combustion air to form a second fuel-air mixture in the second combustion cavity.   
     
     
         22 . The high excess air burner of  claim 21  wherein the oblique angles are greater than 40 degrees and less than 50 degrees. 
     
     
         23 . The high excess air burner of  claim 21  wherein central longitudinal axes of the first combustion air inlets are not coincident with one another, are offset from one another, and are parallel to one another. 
     
     
         24 . The high excess air burner of  claim 21  wherein the rear cover is configured to be coupled to the housing in incremental rotational orientations of ninety degrees, and wherein, irrespective of the incremental rotational orientation of the rear cover, the first combustion air inlets extend at oblique angles to the air inlet axis of the air inlet of the housing. 
     
     
         25 . The high excess air burner of  claim 21 , wherein the rear cover includes an igniter passage for receiving a spark plug or igniter and a flame sensor passage for receiving a flame sensor, wherein the igniter passage and the flame sensor passage are arranged along a reference axis that extends perpendicular to and intersects a central longitudinal axis of the first combustion cavity, and wherein the first combustion air inlets extend at oblique angles to the reference axis. 
     
     
         26 . A burner, comprising:
 a nozzle;   a fuel inlet configured to supply a fuel;   an air inlet configured to supply air;   a flame sensor passage for receiving a flame sensor; and   an ultraviolet-limiting device positioned or provided in the flame sensor passage, the ultraviolet-limiting device having surface features that reduce interference with measurements made by the flame sensor by absorbing or redirecting a portion of ultraviolet light entering the flame sensor passage.   
     
     
         27 . The high excess air burner of  claim 26  wherein the surface features of the ultraviolet-limiting device are threads. 
     
     
         28 . The high excess air burner of  claim 26  wherein the surface features of the ultraviolet-limiting device are grooves. 
     
     
         29 . The high excess air burner of  claim 26  wherein the surface features of the ultraviolet-limiting device are steps. 
     
     
         30 . The high excess air burner of  claim 26  wherein the surface features of the ultraviolet-limiting device are coated by an ultraviolet-reflective material. 
     
     
         31 . The high excess air burner of  claim 26  wherein the surface features of the ultraviolet-limiting device are coated by an ultraviolet-absorbent material. 
     
     
         32 . The high excess air burner of  claim 26  wherein the surface features of the ultraviolet-limiting device are configured such that ultraviolet light traveling parallel or generally parallel to a longitudinal axis of the ultraviolet-limiting device continue uninterrupted through the flame sensor passage toward the flame sensor, and such that a substantial portion of ultraviolet light traveling obliquely to the longitudinal axis of the ultraviolet-limiting device is absorbed or redirected out of the flame sensor passage away from the flame sensor. 
     
     
         33 . The high excess air burner of  claim 26  wherein the ultraviolet-limiting device is provided in the form of a component that is removeably insertable in the flame sensor passage.