The present disclosure generally relates to burners, and more particularly, to a burner with a modular flame retention plate system.
Burners which combust gas, such as propane and natural gas, are well known and widely applied. For example, boilers, furnaces, kilns, incinerators, dryers, and food processing equipment all commonly rely upon the heat generated by such combustion for proper operation.
Prior art burner designs have been created to mix a combustible gas with air and provide a spark for the purpose of starting. Extensive attention has been directed to finding proper mixing ratios and to creating apparatus for obtaining such ratios to most efficiently burn the gas while maximizing BTU output.
One known type of burner includes a substantially cylindrical housing provided with an inlet and an outlet. A motor connected to a blower or a fan wheel is typically connected to the inlet to direct air needed for combustion therethrough. A gas supply conduit typically enters the inlet end of the housing as well, and terminates in a gas nozzle short of the housing outlet end. The area of the housing downstream of the nozzle defines a combustion chamber. An ignition source, such as a spark plug or rod, is positioned proximate the gas nozzle and can be energized as needed.
In order to generate a desired airflow through the housing to the combustion chamber to obtain the desired BTU output and flame shape, various flame retention or nozzle plates have been created. Such plates are typically provided transverse to the longitudinal axis of the housing, and are positioned slightly upstream of the nozzle. The plates typically include various aperture designs to direct forced air therethrough. Additionally, the airflow velocity through the housing is typically controlled by a damper. Accordingly, the various aperture designs of the plates in combination with the control of airflow with the damper create desired characteristics in the resulting flame.
The airflow characteristics influence BTU output, flame stability, CO and NOx emissions. BTU output is a measure of the strength of the flame and its resulting heat output, and is a function of, among other things, the amounts of air and gas combined and the ratio at which they are combined. Flame stability relates to the maintainability and controllability of the flame. If the gas/air ratio becomes too rich or too lean, the flame can be lost or can burn inefficiently. CO and NOx emission control is critical in complying with various environmental regulations. If the flame is not suitably confined, shaped, and directed, all three of the foregoing characteristics will be adversely affected.
A burner assembly includes a generally cylindrical burner tube having an end portion defining a combustion chamber. The burner tube supplies combustion air to the combustion chamber. A gas supply conduit disposed inside the burner tube supplies combustion gas to the combustion chamber. The burner assembly further includes a burner head assembly disposed in the burner tube upstream of the combustion chamber. The burner head assembly includes a plurality of name retention plates having a plurality of changeable flame retention plates removably mounted thereto.
A modular flame retention plate system for use in a burner with a combustion chamber includes a base plate disposed upstream of the combustion chamber, at least one intermediate plate mounted on and downstream of the base plate, and a top plate mounted on and downstream of the intermediate plate. Each of the base plate, the intermediate plate, and the top plate includes a plurality of combustion air flow and combustion gas flow apertures.
A method of controlling delivery of combustion air and combustion gas into a combustion chamber of a burner includes providing a plurality of interaction chambers upstream of the combustion chamber. Each interaction chamber is bound by a flame retention base plate, a flame retention intermediate plate, and a flame retention top plate. The intermediate plate is disposed between the base plate and the top plate. The shape of the interaction chamber is generally defined by the flame intermediate plate. The method further includes providing combustion air to each interaction chamber through a plurality of air flow apertures disposed in the base plate, and distributing combustion gas into each of the interaction chambers by a hub and a plurality of spokes of the intermediate plate. The spoke extend outward from the hub. The hub and the spokes receive combustion gas from at least one gas aperture disposed in the base plate. The method also includes delivering combustion air and combustion gas from each interaction chamber into the combustion chamber and through plurality of gas and air flow apertures disposed in the top plate.
While the invention is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined by the appended claims.
Referring now to the drawings and with specific reference to
A combustion chamber 34 is defined by the space downstream of the outlet 32. Air and gas are mixed and ignited in the combustion chamber 34 as will be discussed in further detail herein. The resulting flame (not shown) is directed outwardly through the outlet 32 of the burner tube 26. The outlet 32 can be positioned proximate any suitable receiving conduit, heat exchanger, or chamber such as that provided in a boiler, furnace, heat exchanger, kiln or the like, to perform useful work therein.
A flame rod assembly 40 is positioned downstream of the plate system 52 to detect and ensure the presence of a flame. Such flame rod assemblies 40 are conventional and may operate by providing a flame rod 42, which upon being heated by the flame, directs a suitable signal to a controller 44 of the burner 20. The controller 44 may be in communication with a higher level integrated control system (not shown), which may take advantage of the signal to provide an indication to an operator as to whether a flame is present.
An ignition spark rod assembly 46 is also provided in the combustion chamber 34. The ignition spark rod assembly 46 provides initial ignition such that upon actuation of the motor 24, and flow of gas through the gas supply conduit 28 and the burner head assembly 30, overall ignition of the burner 20 is insured. Ignition and continuous operation of the burner 20 are verified by the flame rod 42 and the controller 44.
Turning now to
The retention plate system 52 is oriented transverse to the longitudinal axis (not shown) of the burner tube 26. Referring now to
The base plate 60, the intermediate plate 62, and the top plate 64 include a plurality of mounting apertures 66, which can be aligned to receive fasteners 68 for secure mounting of the intermediate plate 62 and the top plate 64 to each other and to the base plate 60. As will become apparent in the following, the plate system 52 can include more than one intermediate plate 62, which may be necessary to attain certain desired burn characteristics. Accordingly, as many intermediate plates as desired can be mounted between the base plate 60 and the top plate 64 to achieve desired burn characteristics.
The plate system 52 provides controlled mixing of the combustion air and combustion gas prior to combustion. The plate system 52 further provides controlled delivery of combustion air, combustion gas, and a mixture thereof to the combustion chamber 34 to achieve desired combustion characteristics. Accordingly, the plate system 52 receives combustion air from the burner tube 26 and combustion gas from the gas supply port 50, provides a controlled and desired mixing of the received gases, and controllably delivers combustion air, combustion gas, and/or a mixture thereof to the combustion chamber 34.
Referring to
Referring to
The intermediate plate 62 includes a center portion, which will be referred to in the following as the hub 80, and a plurality of spokes 82 that extend radially outward from the hub 80. When the intermediate plate 62 is mounted on the base plate 60, the hub 80 partially covers the center aperture 70 of the base plate 60. Furthermore, each spoke 82 partially covers the center aperture 70 and extends radially outward from the hub 80. The angular space between each pair of adjacent spokes 82 defines each of the interaction chambers 74. The hub 80 provides controlled radial distribution of the combustion gas from the center aperture 70 of the base plate 60 to each interaction chamber 74. The shape of each spoke 82 can affect the distribution characteristics of combustion gas in each interaction chamber 74. Additionally, the shape of each spoke 82 can affect the mixing characteristics of combustion air and combustion gas in each interaction chamber 74. Accordingly, each spoke 82 can include one or more slots, channels, and/or apertures (not shown) that receive combustion gas from the center aperture 70 and distribute the combustion gas to each interaction chamber 74 with a desired direction, angle, velocity, dispersion pattern, and pressure.
Referring to
The retention plate system 52 can direct combustion gas, combustion air, and/or a mixture thereof to any location in the combustion chamber 34 with any desired direction, angle, velocity, dispersion pattern, and pressure. To only provide combustion gas to the combustion chamber 34, the hub 80 may include a number of apertures (not shown) that align with corresponding apertures (not shown) on the intermediate plate 62 and the top plate 64. Accordingly, combustion gas can be directly provided to the combustion chamber 34 from the center aperture 70 of the base plate 60 through the intermediate plate 62 and the top plate 64. To only provide combustion air to the combustion chamber 34, each spoke 82 can include one or more apertures (not shown) that align with corresponding air flow apertures 72 of the base plate 60 and corresponding apertures on the top plate 64 to direct combustion air to the combustion chamber 34. In effect, the combustion air is routed from the burner tube 26 directly to the combustion chamber 34 without being mixed with any combustion gas.
In some burners with high BTU output, the interaction chambers 74 may need to be larger than an interaction chamber provided by having only one intermediate plate 62. Accordingly, in such burners, more than one intermediate plate 62 can be mounted between the base plate 62 and the top plate 64. Furthermore, as one of ordinary skill in the art will readily appreciate, having more than one intermediate plate 62 provides the opportunity to place dissimilar intermediate plates 62 between the base plate 60 and the top plate 64. Having dissimilar intermediate plates 62 in the plate system 52 provides a wide range of gas and air mixing and delivery thereof to the combustion chamber 34 that may not be possible with having only one intermediate plate 62.
The sizes, locations, and group patterns of various apertures on the base plate 60, the intermediate plate 62, and the top plate 64 can affect the flow rate of combustion air, combustion gas, and a mixture thereof in the interaction chambers 74. Furthermore, the sizes, locations, and patterns of various apertures relative to each other affect delivery of combustion air and combustion gas to the combustion chamber 34. For example, misalignment of corresponding apertures when the intermediate plate 62 and the top plate 64 are mounted on the base plate 60 can affect the direction of flow out of the top plate apertures 90 and into the combustion chamber 34. The sizes of the apertures relative to each other can affect the pressure and velocity of the flow in the combustion chamber 34, while the size of corresponding apertures can further affect the shape of the flow in the combustion chamber 34. For example, an aperture on the top plate 64 that corresponds and communicates with smaller apertures on the intermediate plate 62 and the base plate 60 may provide an expanding flow (i.e., the expansion affecting flow pressure) out of the apertures 90 of the top plate 64. Similarly, an aperture on the top plate 64 that corresponds and communicates with larger apertures on the intermediate plate 62 and the base plate 60 may provide a contracting flow. One of ordinary skill in the art will appreciate from the foregoing that the sizes, locations, and group patterns of the various apertures on the plate system 52 can offer unlimited ways by which the flow characteristics upstream of and in the combustion chamber 34 can be controlled.
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The arc shaped slots 100 and air flow apertures 102 can vary in number, size, and distribution pattern so as to provide a desired air flow characteristic. One function of the air flow apertures 102 is to stabilize the flame that forms in the combustion chamber 34. One of ordinary skill in the art will appreciate that such flame stabilization is directly related to the noise generated by the burning process.
In certain burner applications, it may be necessary to reduce BTU output of the burner by reducing the combustion air flowing into the combustion chamber 34. To reduce the air flowing into the combustion chamber 34, the plate system 52 of the disclosed example also includes a number of optional arc shaped tabs 126 that can be attached to the perimeter portion 124 of the plate system 52. Referring to
In operation, the apertures 90 of the top plate 64 deliver a mixture of combustion air and combustion gas from each interaction chamber 74 into the combustion chamber 34. The ignition spark rod assembly 46 ignites the mixture and a primary flame is formed downstream of each aperture 90. Additionally, the mixture of combustion gas and combustion air entering the combustion chamber 34 from the perimeter regions 124 are ignited by the primary flame to form a secondary flame and more contiguous flame that blankets the discrete flames generated by the apertures 90 of the top plate 64.
One of ordinary skill in the art will appreciate from the foregoing that the plate system 52 provides controlled mixing of the combustion air and the combustion gas and a controlled delivery thereof to the combustion chamber 34. Such controlled mixing and delivery can provide a wide range of BTU outputs for the burner 20, and provide flame stabilization, which reduces burner noise. Furthermore, the plate system 52 is modular, and therefore, highly customizable for use in various types of burners. Additionally, the plate system 52 facilitates controlled mixing and delivery of the combustion air and the combustion gas in a very small cross section of the burner tube 26. Accordingly, burners using the disclosed plate system 52 can have short burner tubes 26, and therefore, can be used in applications where space accommodations for the burner are minimal.
Persons of ordinary skill in the art will appreciate that, although the teachings of the invention have been illustrated in connection with certain embodiments, there is no intent to limit the invention to such embodiments. On the contrary, the intention of this application is to cover all modifications and embodiments fairly falling within the scope of the teachings of the invention.
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Number | Date | Country |
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2224824 | May 1990 | GB |