The present disclosure is directed generally to high intensity gas-fired infrared emitters, and more specifically, to high intensity gas-fired infrared emitters including a flame arrestor and a cellular combustion member to provide improved conversion efficiency.
Gas-fired radiant emitters are used, for example, for drying coating, controlling moisture profiles, processing industrial building equipment, curing, and other applications that require a large amount of heat to be transferred to a load in a very short amount of time. Typically, many emitters are positioned side-by-side to extend across an industrial automated machine or production line.
Unfortunately, a lot of time is required to maintain a large number of emitters positioned side-by-side. Moreover, conventional gas-fired radiant emitters produce carbon monoxide (CO) emissions at 100 ppm and nitrogen oxide (NOx) emissions at 30 ppm, both referenced to 3% O2 in dry flue products, which are undesirable. It is advantageous to improve the overall conversion efficiency of gas-fired radiant emitters.
The present disclosure is directed generally to high intensity gas-fired infrared emitters including a flame arrestor and a cellular combustion member to provide improved conversion efficiency. The disclosed embodiments provide advantages over conventional emitters by making the device less prone to instances of backfire during operation. Additionally, the disclosed embodiments minimize energy loss through components of the emitter near the external surface which transfers heat. The combination of a flame arrestor and cellular surface panel allows for a high surface area with minimal losses, resulting in improved conversion efficiency.
Generally, in one aspect, a high intensity gas-fired infrared emitter is provided. The high intensity gas-fired infrared emitter includes (i) a frame having a plurality of side walls, an open bottom, and an open top; (ii) a flame arrestor mounted inside the frame and including a bottom, a top surface having a recess, and a plurality of apertures extending from the bottom to the recessed top surface; and (iii) a cellular surface panel formed of a plurality of cells and mounted inside the recess of the flame arrestor such that the plurality of apertures of the flame arrestor form pathways which extend into the cellular surface panel.
According to an embodiment, each of the plurality of cells of the cellular surface panel comprises a geometry to form a restricted path for products of combustion.
According to an embodiment, the cellular surface panel comprises at least two consecutively connected solid porous bodies.
According to an embodiment, at least two consecutively connected solid porous bodies have different sizes.
According to an embodiment, the emitter further includes a body mounted within the frame and a resilient element configured to retain the flame arrestor, the cellular surface panel and the body within the frame.
According to an embodiment, the body supports a deflector plate positioned dimensionally offset relative to the body.
According to an embodiment, an offset is arranged between the flame arrestor and the body mounted within the frame to increase a volume of a chamber formed therein.
According to an embodiment, the flame arrestor is made of a lightweight ceramic fiber material composed principally of aluminum oxide and silicon dioxide.
According to an embodiment, the emitter further includes a fire check assembly coupled to the body to stop gas flow to the cellular surface panel in a failure event.
Generally, in another aspect, a high intensity gas-fired infrared emitter is provided. The high intensity gas-fired infrared emitter includes (i) a frame having at least one side wall, an open bottom, and an open top; (ii) a flame arrestor mounted inside the frame and including a bottom, a top surface having a recess, and a plurality of apertures extending from the bottom to the recessed top surface; (iii) a cellular surface panel mounted inside the recess of the flame arrestor such that the plurality of apertures of the flame arrestor form pathways which extend into the cellular surface panel; and (iv) a fire check assembly coupled with the emitter. The assembly includes a solder joint positioned proximate a gas outlet, and a plunger rod fixed to the solder joint and in a compressed state via a resilient member. The solder joint is configured to break when exposed to a flame causing the plunger rod to be displaced to close a gas inlet.
According to an embodiment, the resilient member is a spring urging the plunger rod towards the gas inlet.
According to an embodiment, the cellular surface panel comprises at least two consecutively connected solid porous bodies.
According to an embodiment, the flame arrestor is made of a lightweight ceramic fiber material composed principally of aluminum oxide and silicon dioxide.
According to an embodiment, the cellular surface panel is formed from silicon carbide (Si—SiC).
Generally, in a further aspect, a method of operating a high intensity gas-fired infrared emitter is provided. The emitter includes a frame, a flame arrestor mounted inside the frame, and a cellular surface panel mounted inside the flame arrestor. The method of operating includes the steps of (i) introducing a combustible mixture into the high intensity gas-fired infrared emitter through an inlet manifold; (ii) dispersing the combustible mixture into a cavity; (iii) forcing, by a deflector plate, the combustible mixture to fill a chamber, (iv) forming a pressure tight seal within the chamber; (v) passing the combustible mixture through apertures within the flame arrestor to maintain a low air-gas temperature prior to combustion; and (vi) igniting the mixture to heat cells of the cellular surface panel.
According to an embodiment, the chamber is formed by at least one gasket, the flame arrestor, a cast iron body, the frame, and at least one resilient member.
It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein.
The foregoing will be apparent from the following more particular description of example embodiments of the present disclosure, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present disclosure.
A description of example embodiments of the invention follows. Although the gas-fired infrared emitter assembly shown in the figures is shown in an upward orientation, the gas-fired infrared emitter is typically operated in the downward orientation. Thus, the description of the assembly shown in the figures is not intended to be limited to a particular orientation. The terms “top” and “bottom” as used herein describe elements of the assembly based on the upward orientation of the assembly shown in the figures. In other words, for example, the “open bottom side 4A” also represents “an open top side” when the assembly is rotated 180 degrees in use.
Referring to
To retain the cellular surface panel in place within the flame arrestor 9, extensions 7 are included either integrally or otherwise within frame 1. Extensions 7 extend from horizontal edges 3 in a direction away from side walls 2. Extensions 7 can be made of any suitable metal, for example, stainless steel. In an example embodiment, two extensions 7 are arranged on each of the longer sides of a rectangular frame 1. Additional or fewer extensions are contemplated. Any suitable sizes and shapes of extensions are contemplated. In an example embodiment, the horizontal edges 3 include indentations such that the non-indented portions retain the cellular surface panel in place within the flame arrestor 9. The slots 5 within the frame 1 are arranged to receive resilient elements 6 on each side of the emitter. Resilient elements 6 can be springs or any suitable alternative.
In an example embodiment, metallic components are formed inside each of the four corners of the frame 1. Such metallic components can be formed from a high temperature metal, such as, stainless steel, or any suitable alternative. The metallic corner components can be sized such that at least 0.5 inches of metallic material, for example, extends in length and width directions, normal to the open horizontal face 4B. The corner components can be fixed into position mechanically via a weld or any suitable alternative along with additional compression force produced by resilient elements 6.
A rectangular gasket 8 is arranged inside the outer edge of frame 1 and within the boundary of the horizontal edges 3. The rectangular gasket 8 can be made from high temperature ceramic paper or any suitable alternative. Coincident to the bottom side of paper gasket 8 is a flame arrestor 9, formed of high temperature ceramic fiber insulation or any suitable alternative.
Referring to
The flame arrestor 9 may be formed of a lightweight ceramic fiber material suitable for 3000 F and composed principally of aluminum oxide (Al2O3) and silicon dioxide (SiO2). In an example embodiment, the suitable material is composed of approximately 78 percent aluminum oxide (Al2O3) and/or 22 percent silicon dioxide (SiO2) and/or a density of 25 lb/ft3. The flame arrestor 9 also may exhibit continuous use up to 2950 degrees Fahrenheit (or 3000 degrees Fahrenheit), thermal conductivity of 1.25 Btu/(hr)(ft2)(° F./in), and 2.3 percent shrinkage at 2500 degrees Fahrenheit. The high temperature range, high compressive strength, and minimal shrinkage allow the material to be processed with 400-800 holes, for example, without any surface cracking ensuring long emitter life. The insulation properties of the flame arrestor 9 effectively hold an air/gas mixture temperature on the bottom side of the flame arrestor 9 (where an air/gas mixture enters the emitter) approximately 2300 degrees Fahrenheit lower than a main combustion zone on the opposite side. The flame arrestor 9 effectively insulates the frame 1 from the cellular surface panel 10, thus minimizing losses and increasing conversion efficiency of the emitter.
The cellular surface panel 10 may have a profile that substantially corresponds in shape and size to the flame arrestor recess 42 and to the top opening 4B of the frame 1.
Referring back to
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Once the air-gas mixture exits the fire check assembly 18, the air-gas mixture is introduced into the infrared emitter through the casting inlet manifold 17 where it expands into the annular casting manifold before dispersing into the cavity 19, formed from the general convex envelope of the cast iron body 12. Once the air/gas mixture reaches the cavity 19, it encounters the deflector plate 15, which forces the air-gas mixture to fill the chamber 13 through the offset gap 16 (around all sides of the casting body 12), ensuring equal distribution and uniform emitter surface temperature profile.
The ceramic paper gasket 8A, graphite gasket 11, flame arrestor 9, casting body 12, frame 1, and resilient elements 6 not only allow the formation of chamber 13, but can also create a pressure tight seal. The gasket combination 8A and 11 can create an increased offset between the flame arrestor 9 and the casting body 12, increasing the volume of chamber 13 and dwell time of the air/gas mixture, further improving distribution effectiveness. The casting body 12, frame 1, and resilient elements 6 may be configured such that when in the assembled position, resilient elements 6 exert a homogeneous compressive force on the casting body 12, which compresses gaskets 8A and 11 and the flame arrestor 9 against the horizontal edges 3 of the frame 1. The composition of gasket 11 is such that the gasket spreads when compressed to fill any small voids that may be present between the casting body 12, frame 1, and flame arrestor 9. Additional sealing characteristics are achieved as the temperature of the graphite gasket 11 is increased beyond room temperature.
Once the reactants have reached the chamber 13, the mixture is forced to pass through apertures 44 in the flame arrestor 9. In an example embodiment, apertures 44 are annular nozzles. The flow path travel distance through each aperture in the flame arrestor 9 is such that there is enough material to insulate the air-gas mixture in the chamber 13 from the combustion zone temperatures on the recess 42, maintaining a low air-gas premix temperature inside of the emitter (prior to combustion), which is vital in reducing the occurrence of backfire during normal operation of the emitter. The flame arrestor 9 also insulates the metallic vertical side walls 2 of the frame 1 from the cellular surface panel 10. This effect minimizes energy loss through parts of the emitter near the external surface 4B (the surface of the emitter that is meant to transfer heat). The material composition of the flame arrestor 9 can both ensure proper function through the insulation of the chamber 13 and minimize losses through the frame 1.
As the gas mixture enters the inlet of each aperture 44, the fluid velocity increases, creating well defined fluid streams that extend into the interconnected truncated cubes of the cellular surface panel 10. An external ignition source may ignite the mixture and each of the apertures 44 can form very well defined flames that reach the top of the surface 47 of the cellular surface panel (shown in
In an event that the emitter is operated outside the specified operating range and/or in an event or string of events that leads to failure (e.g., backfire into the chamber 13), solder joint 63 of the frame 61 and the plunger rod 65 are positioned to cause quick failure of the joint 63. Failure of the joint 63 releases the compression force caused by resilient element 67 resting in a compressed position against cross member 66. Movement of resilient element 67 from a compressed state to an uncompressed state releases the compression force, moving plunger 62 into a coincident position with counter-bore 59. The length of resilient element 67 is such that the opposite side of resilient element 67 remains in contact with cross member 66 causing enough of a compression force on plunger 62 to shut off the air/gas flow into the emitter.
While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. For example, the cells 48 of the cellular surface panel 10 can be formed of any particular solid porous body geometry. The cellular surface panel 10 can be formed of any number of consecutively connected solid porous body geometries, can have any number of layers, and can be held in place using additional structural support extending from horizontal edges 3 of the frame 1. The flame arrestor 9 can have a recess 42 of any depth and wall thickness to accommodate the dimensional boundaries that define the cellular surface panel 10, can have any number of apertures, not necessarily round, in any pattern, and the apertures may contain larger recessed holes for increased retention aperture surface area.
While several inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, and/or methods, if such features, systems, articles, materials, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/306,214, filed on Mar. 10, 2016 and entitled “High Intensity Gas Fired Infrared Emitter”, the entire disclosure of which is incorporated herein by reference.
Number | Date | Country | |
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62306214 | Mar 2016 | US |