Burner assembly
A burner assembly including a housing having an air inlet and a burner end, a motor, and an impeller mounted in the housing. The impeller is in fluid communication with the air inlet, in mechanical communication with the motor, and adapted to direct air from the air inlet towards the burner end of the housing. The burner assembly also includes at least one pre-mix gas injection nozzle mounted in the housing. Each of the at least one pre-mix gas injection nozzle has at least one orifice adapted to direct gaseous fuel into the housing. The burner assembly further includes a spin vane comprising at least one spin vane blade. The spin vane is mounted in the burner end of the housing and adapted to direct the flow of air in the burner end. The burner assembly still further includes an igniter mounted in the burner end of the housing. The igniter is adapted to ignite the air and fuel mixture in the burner end of the housing to produce a main flame.
This application is a continuation-in-part of U.S. patent application Ser. No. 10/957,252 filed on Oct. 1, 2004 and entitled “Burner Assembly” which relates back to Provisional Patent Application Ser. No. 60/508,138 filed on Oct. 3, 2003 and entitled “Burner Assembly.”
FIELD OF THE INVENTIONThis invention relates generally to an improved burner assembly, and more particularly, to an improved burner assembly for heating and drying aggregate materials used in connection with the production of hot mix asphalt.
BACKGROUND AND DESCRIPTION OF THE PRIOR ARTIt is known to use a burner assembly to heat and dry aggregate materials used in connection with the production of hot mix asphalt. See, e.g., U.S. Pat. No. 5,700,143, No. 5,511,970, No. 4,559,009 and No. 4,298,337. However, conventional burner assemblies suffer from several disadvantages. For example, conventional burner assemblies are incapable of producing a flame configuration satisfactory for asphalt production in a variety of different-sized combustion chambers. As a result, burner assemblies typically include adjustable spin vanes or spin racks to accommodate different-sized combustion chambers. For example, U.S. Pat. No. 6,488,496 of Feese et al. describes a compact combination burner with an adjustable spin rack. Adjustable spin vanes, however, increase the cost of manufacture and maintenance, and the amount of labor required to operate the burner. In addition, conventional burner assemblies experience excessive temperatures in the area of the burner flame, resulting in damage to components in the area of the burner flame. Further, in conventional burner assemblies, the components in the area of the burner flame are exposed to debris produced in the combustion chamber.
It would be desirable, therefore, if an apparatus could be provided that would selectively fire on gaseous fuel, liquid fuel, or both gaseous and liquid fuel. It would also be desirable if such an apparatus could be provided that would fire on gaseous and/or liquid fuels without physically altering the components of the apparatus, changing the firing rate of the apparatus, or shutting down the apparatus. It would be further desirable if such apparatus could be provided that would fire on oil or liquid propane without changing the atomizing nozzle. It would be still further desirable if such an apparatus could be provided that would supply natural gas or propane around the atomizing nozzle for use as pilot fuel. In addition, it would be desirable is such an apparatus could be provided that would produce a stable flame configuration having a short flame length and a narrow flame diameter adapted for use on a wide variety of different-sized combustion chambers. It would also be desirable if such an apparatus could be provided that would more completely and uniformly mix fuel and air in order to obtain more rapid combustion and improve combustion intensity, thereby reducing the combustion space required in the asphalt drum and lowering carbon monoxide (CO) emissions in the combustion space. It would be still further desirable if such an apparatus could be provided that would achieve reduced emissions of the oxides of nitrogen (NOx). In addition, it would be desirable if such an apparatus could be provided that would be capable of firing on low excess air pre-mix gas. It would also be desirable if such an apparatus could be provided that would produce a stabilizing gas base flame. It would be further desirable if such an apparatus could be provided that would reduce the temperature of the dryer drum breech plate where the burner is mounted. It would be still further desirable if such an apparatus could be provided that would eliminate the need to adjust spin vanes to achieve a desired flame configuration. It would also be desirable if such an apparatus could be provided that would be less complicated and expensive to manufacture, operate and maintain than conventional burners. It would be further desirable if such an apparatus could be provided that would reduce the temperatures in the area of the burner flame and the resulting damage to components in the area of the burner flame. It would be still further desirable if such an apparatus could be provided that would reduce the exposure to debris produced in the combustion chamber experienced by components in the area of the burner flame.
ADVANTAGES OF THE PREFERRED EMBODIMENTS OF THE INVENTIONAccordingly, it is an advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus capable of selectively firing on gaseous fuel, liquid fuel, or both gaseous and liquid fuel. It is also an advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus capable of firing on gaseous and/or liquid fuels without physically altering the components of the apparatus, changing the firing rate of the apparatus, or shutting down the apparatus. It is a further advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus adapted to fire on oil or liquid propane without changing the atomizing nozzle. It is another advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus that is capable of supplying natural gas or propane to the atomizing nozzle for use as pilot fuel. It is also an advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus for producing a stable main flame configuration that has a short flame length and a narrow flame diameter. It is also an advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus for producing a main flame configuration that is adapted for use on a wide variety of different-sized combustion chambers having different-sized combustion spaces. It is another advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus that more rapidly, completely, and uniformly mixes fuel and air, thereby providing a more rapid combustion, improving combustion intensity, reducing the combustion space required in the asphalt drum, and reducing CO emissions in the combustion space. It is yet another advantage of the preferred embodiments of the invention described and claimed herein to reduce NOx emissions. It is a further advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus having the capability of firing on low excess air pre-mix gas. It is a still further advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus for producing a stabilizing gas base flame. It is still another advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus that reduces the temperature of the dryer drum breech plate. It is a further advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus that eliminates the need for adjustable spin vanes in order to achieve a desired flame configuration. It is another advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus having improved aerodynamics which reduce energy consumption and body pressure and produce a more free flowing burner assembly. It is still another advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus which produces reduced noise levels during operation. It is yet another advantage of the preferred embodiments of the invention described and claimed herein to provide an apparatus that is less complicated and expensive to manufacture, operate and maintain than conventional burner assemblies. It is yet another advantage of the preferred embodiments of the invention to provide an apparatus that reduces the temperatures in the area of the burner flame and the resulting damage to components in the area of the burner flame. It is also an advantage of the preferred embodiments of the invention to provide an apparatus that reduces the exposure to debris produced in the combustion chamber experienced by components in the area of the burner flame.
Additional advantages of the preferred embodiments of the invention will become apparent from an examination of the drawings and the ensuing description.
EXPLANATION OF TECHNICAL TERMSAs used herein, the term “mounted about the periphery of the housing” means that the at least one pre-mix gas injection nozzle is mounted within the interior of the housing of the burner assembly such that the nozzles do not extend to center of housing. More particularly, the term “mounted about the periphery of the housing” means that the at least one pre-mix gas injection nozzle is mounted within the interior of the housing of the burner assembly such that the nozzles leave an open area in the center of the housing through which the primary air tube, the pilot assembly and the like may pass unimpeded.
As used herein, the term “centrally located in the housing” means that the pilot assembly is located and arranged in the housing of the burner assembly such that it passes through the open area in the center of the housing produced by the arrangement of the pre-mix gas injection nozzles.
SUMMARY OF THE INVENTIONThe invention claimed herein comprises a burner assembly including a housing having an air inlet and a burner end, a motor, and an impeller mounted in the housing. The impeller is in fluid communication with the air inlet, in mechanical communication with the motor, and adapted to direct air from the air inlet towards the burner end of the housing. The burner assembly also includes at least one pre-mix gas injection nozzle mounted in the housing. Each of the at least one pre-mix gas injection nozzle has at least one orifice adapted to direct gaseous fuel into the housing. The burner assembly further includes a spin vane comprising at least one spin vane blade. The spin vane is mounted in the burner end of the housing and adapted to direct the flow of air in the burner end. The burner assembly still further includes an igniter mounted in the burner end of the housing. The igniter is adapted to ignite the air and fuel mixture in the burner end of the housing to produce a main flame.
In a preferred embodiment, a liquid fuel system is provided in the burner assembly. In this preferred embodiment, an primary air tube is mounted within the housing. The primary air tube has an inlet end located downstream of the impeller and an outlet end located adjacent to the burner end. Also in this preferred embodiment, an atomizing nozzle is mounted on the outlet end of the primary air tube, a liquid fuel supply tube is mounted within the primary air tube so as to convey liquid fuel to the atomizing nozzle, a compressed atomizing air supply tube is mounted within the primary air tube so as to convey compressed air to the atomizing nozzle, and a ring is mounted around the periphery of the outlet end of the primary air tube. Also in a preferred embodiment of the burner assembly of the invention, a converging focusing cone and a diverging conical discharge section are mounted to the burner end, and a stabilizing gas base flame and a centrally-located pilot are provided in the burner end of the burner assembly. In another preferred embodiment of the invention, the burner assembly includes an isolation shroud at the burner end.
In order to facilitate an understanding of the invention, the preferred embodiments of the invention are illustrated in the drawings, and a detailed description thereof follows. It is not intended, however, that the invention be limited to the particular embodiments described or to use in connection with the apparatus illustrated herein. Various modifications and alternative embodiments such as would ordinarily occur to one skilled in the art to which the invention relates are also contemplated and included within the scope of the invention described herein.
The presently preferred embodiments of the invention are illustrated in the accompanying drawings, in which like reference numerals represent like parts throughout, and in which:
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However, it is contemplated within the scope of the invention that the spin vane may be adjustable. It is further contemplated within the scope of the invention that the spin vane may be mounted in the burner assembly at any suitable location and the spin vane blades may be of any suitable configuration, angle, number and/or spacing adapted to contribute to the swirling flow of air and the stability of the flame produced in the burner end. While
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In operation, the several advantages of the burner assembly of the invention are achieved. For example, the preferred burner assembly is capable of selectively firing on gaseous fuel, liquid fuel, or both gaseous and liquid fuel. The preferred burner assembly is capable of firing on gaseous and/or liquid fuels without physically altering the components of the apparatus, changing the firing rate of the apparatus, or shutting down the apparatus. The preferred burner assembly is adapted to fire on oil or liquid propane without changing the atomizing nozzle. The preferred burner assembly is capable of supplying natural gas or propane to the atomizing nozzle for use as pilot fuel.
In addition, the preferred burner assembly produces a short, narrow and stable main flame configuration. The improved main flame configuration reduces the amount of combustion space required to heat and dry aggregate materials for the production of hot mix asphalt. The improved main flame configuration is adapted for use on a wide variety of different-sized combustion chambers having different-sized combustion spaces.
Further, the spacing and configuration of the spin vane, the ring, and the pre-mix gas injection nozzles in the preferred embodiment of the invention results in a more complete and uniform mixture of combustion air, gaseous fuel and/or liquid fuel. The spin vane may be fixed because adjustment of the flame configuration is not required, even when using the burner assembly with a variety of different-sized dryer drums. As a result, costly and complicated adjustable spin vanes may be eliminated. In addition, the converging focusing cone section reduces the temperature of the dryer drum breech plate.
Still further, the configuration and arrangement of the preferred burner assembly provides improved aerodynamics. The configuration and arrangement of the preferred burner assembly more rapidly, completely, and uniformly mixes fuel and air, thereby providing a more rapid combustion, improving combustion intensity, reducing the combustion space required in the asphalt drum, and reducing CO emissions in the combustion space. The improved aerodynamics of the preferred burner assembly results in reduced energy consumption and body pressure. In addition, the improved aerodynamics of the preferred burner assembly produces a more free flowing burner assembly. Still further, the preferred burner assembly results in reduced noise levels during operation and reduced NOx emissions.
Additionally, the preferred burner assembly is capable of firing on low excess air pre-mix gas. The preferred burner assembly produces a stabilizing gas base flame. The preferred burner assembly is also less complicated and expensive to manufacture, operate and maintain than conventional burner assemblies.
Finally, the preferred burner assembly reduces the temperatures in the area of the burner flame and the resulting damage to components in the area of the burner flame. The preferred burner assembly also reduces the exposure to debris produced in the combustion chamber experienced by components in the area of the burner flame. Although this description contains many specifics, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments thereof, as well as the best mode contemplated by the inventors of carrying out the invention. The invention, as described herein, is susceptible to various modifications and adaptations, as would be understood and appreciated by a person having ordinary skill in the art to which the invention relates.
Claims
1. A burner assembly comprising:
- (a) a housing having an air inlet and a burner end having an opening;
- (b) a motor;
- (c) an impeller mounted in the housing, said impeller being in fluid communication with the air inlet, in mechanical communication with the motor and adapted to direct air from the air inlet towards the burner end of the housing;
- (d) at least one pre-mix gas injection nozzle mounted in the housing, each of said at least one pre-mix gas injection nozzle having at least one orifice adapted to direct gaseous fuel into the housing;
- (e) a spin vane comprising at least one spin vane blade, said spin vane being mounted in the burner end of the housing and adapted to direct the flow of air in the burner end; and,
- (f) an igniter mounted in the burner end of the housing, said igniter being adapted to ignite the air and fuel mixture in the burner end of the housing to produce a main flame.
2. The burner assembly of claim 1 wherein the motor is a variable speed motor.
3. The burner assembly of claim 1 wherein the at least one pre-mix gas injection nozzle is mounted about the periphery of the housing.
4. The burner assembly of claim 1 wherein each of the at least one orifice in the at least one pre-mix gas injection nozzle has a diameter of no more than about 0.125 inches.
5. The burner assembly of claim 1 wherein the spin vane is fixedly mounted in the burner end.
6. The burner assembly of claim 1 wherein each of the at least one spin vane blade of the spin vane is tapered.
7. The burner assembly of claim 1 wherein each of the at least one spin vane blade of the spin vane has a non-planar cross-sectional shape.
8. The burner assembly of claim 1, further including:
- (g) an air deflector mounted in the housing, said air deflector being adapted to direct air flow from the impeller to the burner end.
9. The burner assembly of claim 1, further including:
- (h) a transition section located downstream of the impeller and adapted to direct air flow from the impeller to the burner end.
10. The burner assembly of claim 1, further including:
- (i) a seal skirt mounted adjacent to the burner end, said seal skirt being adapted to prevent air from entering a dryer drum.
11. The burner assembly of claim 1, further including:
- (j) a heat shield mounted adjacent to the burner end, said heat shield being adapted to be attached to a rotating dryer drum and prevent air from entering said dryer drum.
12. The burner assembly of claim 1, further including:
- (k) at least one screen mounted in the housing of the burner assembly downstream from the impeller.
13. The burner assembly of claim 12 wherein the at least one screen mounted in the housing of the burner assembly downstream from the impeller includes a straightening screen adapted to produce a uniform air flow velocity in the burner assembly and a mixing screen adapted to produce a uniform air flow velocity in the burner assembly and mix combustion air and fuel in the burner assembly.
14. The burner assembly of claim 1, further including:
- (l) a pre-mix cone located downstream from the impeller and adapted to direct air flow from the impeller to the burner end.
15. The burner assembly of claim 14 wherein the pre-mix cone has an included angle of approximately 15°.
16. The burner assembly of claim 1, further including:
- (m) a converging focusing cone located in the burner end, said converging focusing cone being adapted to accelerate the velocity of air flow in the burner end.
17. The burner assembly of claim 16 wherein the converging focusing cone is removably mounted to the burner assembly.
18. The burner assembly of claim 1, further including:
- (n) a diverging conical discharge section located in the burner end.
19. The burner assembly of claim 18 wherein the diverging conical discharge section includes at least one expansion and contraction crease.
20. The burner assembly of claim 1, further including:
- (o) an primary air tube mounted within the housing, said primary air tube having an inlet end and an outlet end, said inlet end being located downstream of the impeller and said outlet end being located in the burner end;
- (p) an atomizing nozzle located at the outlet end of the primary air tube;
- (q) a liquid fuel supply tube mounted within the primary air tube, said liquid fuel supply tube being adapted to convey liquid fuel to the atomizing nozzle;
- (r) a swirl plate mounted around the periphery of the outlet end of the primary air tube;
- (s) a compressed atomizing air supply tube mounted within the primary air tube, said compressed atomizing air supply tube being adapted to convey compressed air to the atomizing nozzle.
21. The burner assembly of claim 20 wherein the burner assembly is adapted to selectively fire on gaseous fuel, liquid fuel or both gaseous fuel and liquid fuel.
22. The burner assembly of claim 20 wherein the liquid fuel supply tube is adapted to convey gaseous fuel to produce a stabilizing gas base flame in the burner end.
23. The burner assembly of claim 20 wherein the swirl plate mounted around the periphery of the outlet end of the primary air tube is a slotted ring or a flapped ring.
24. The burner assembly of claim 20, further including:
- (t) a pilot assembly mounted at the burner end, said pilot assembly being adapted to produce a pilot flame.
25. The burner assembly of claim 24 wherein the pilot assembly is centrally located in the housing of the burner assembly and surrounds at least a portion of the atomizing nozzle.
26. The burner assembly of claim 1 further including an isolation shroud at the burner end.
27. The burner assembly of claim 26 wherein the isolation shroud is removably attached to the burner end.
28. The burner assembly of claim 26 wherein the isolation shroud is attached to the burner end by at least one suspension spoke.
29. The burner assembly of claim 26 wherein the isolation shroud surrounds and partially encloses the burner nose.
30. The burner assembly of claim 26 wherein the isolation shroud is adapted to be purged with a fluid.
Type: Application
Filed: Jul 3, 2007
Publication Date: Nov 13, 2008
Inventors: Malcolm Swanson (Chickamauga, GA), Michael Swanson (Chickamauga, GA), Andrew Hobbs (Sheffield), Russell Fountain (East Ridge, TN), Kelly Knight (Ringgold, GA), Eric Wattenbarger (Flat Rock, AL)
Application Number: 11/824,930
International Classification: F23Q 2/00 (20060101);