WO2008004734A1

WO2008004734A1 - Flame structure of gas burner

Info

Publication number: WO2008004734A1
Application number: PCT/KR2006/005867
Authority: WO
Inventors: Eun Seong Cho; Seung Beom Cho
Original assignee: Kyung Dong Navien Co Ltd
Current assignee: Kyung Dong Navien Co Ltd
Priority date: 2006-07-07
Filing date: 2006-12-29
Publication date: 2008-01-10
Anticipated expiration: 2009-01-07
Also published as: JP5200016B2; KR100778716B1; JP2010501818A; EP2041490A1; CN101495806A; US20090291402A1; CN101495806B; EP2041490A4

Abstract

The present invention is directed to a fire hole part structure of a gas burner, which is constructed to be manufactured at a low cost, can improve flame stability, and can prevent incomplete combustion due to the length of flame. The structure is provided to a premixing ignition burner, which is installed to apply heat to a heat exchanger of a boiler, and includes fire hole pieces (20) which are installed parallel to one another in mounting openings (13) of a burner body (11), and each of which is defined with fire holes (23) at regular intervals. An upper wall (21) of at least one of the fire hole pieces (20) is bent or curved to extend in at least two directions, and the fire holes (23) are defined through respective surface portions of the upper wall (21), which extend in different directions, to face different directions.

Description

Description FLAME STRUCTURE OF GAS BURNER

Technical Field

[1] The present invention relates to a fire hole part structure of a gas burner, which can improve flame stability through impingement injection of flame through fire holes and can reduce the generation of incomplete combustion products. Background Art

[2] As a gas burner for a boiler or a water heating system, a Bunsen burner was used in the past, but a premixing ignition type burner is being mainly used these days since it can reduce the generation of pollutants and decrease the size of a combustion chamber.

[3] The premixing ignition type burner has a fire hole part which has defined therein a plurality of fire holes for injecting the premixture of fuel gas and air to thereby produce flame. A conventional fire hole part has a structure in which fire holes are defined through a single plate member comprising a flat plate or a cylindrical plate. The conventional fire hole part structure has problems in that the combustion surface thereof is likely to be distorted or the shape of the fire holes is likely to be changed due to deformation by thermal stress, whereby incomplete combustion or backfiring can be caused.

[4] In order to overcome these problems, a fire hole part structure, which employs a metal fiber mat formed by weaving metal fiber, or a ceramic plate formed by sintering ceramic, has been disclosed in the art. However, this structure incurs substantial material costs, and the manufacturing procedure is complicated, so that the manufacturing costs are increased. Also, because the configuration of a premixer is complex, pressure loss increases, the flame is unstable, and noise occurs. Further, the fire hole part structure suffers from defects due to the characteristics of the material thereof. For example, in the case of the metal fiber mat, since it has a certain degree of softness, the combustion surface and fire holes are likely to be distorted due to deformation by the application of force upon assembly and due to drooping after installation. In the case of the sintered ceramic plate, as condensed water drips from the h eat exchanger, arranged above the ceramic plate, the fire hole part can be adversely affected.

[5] FIG. 1 illustrates another conventional fire hole part structure for a gas burner, which is formed at a reduced cost using a metal plate and can solve the problems caused by deformation due to thermal stress.

[6] In the illustrated conventional fire hole part, a plurality of fire hole pieces 120 is installed in a parallel arrangement in mounting openings 110 which are defined in the upper end of a burner body 100. Each fire hole piece 120 is bent so as to define an elongate channel which substantially has the sectional shape of a U rotated 180° so that it opens downward. A plurality of fire holes 121 is defined at regular intervals through the upper surface of each fire hole piece 120. Both ends of each fire hole piece 120 are fastened to the burner body 100 by fastening covers 123 and bolts.

[7] Due to the fact that the fire hole part structure is constituted by the fire hole pieces

120, which are separately formed using metal plates, the manufacturing cost can be reduced. Further, since the respective separate fire hole pieces 120 are individually fastened, deformation of the entire fire hole part due to thermal stress can be decreased. Also, by changing the number of fire hole pieces 120 for ease of mounting, the heating capacity of a burner can be easily adjusted. Disclosure of Invention Technical Problem

[8] However, the flame of a premixing ignition burner has narrow limits of inflammability, unlike the diffusion flame of a Bunsen burner. In the case of an ideal premixture combustion type flame, which is produced through the combustion of, for example, LNG, which contains methane as a main constituent thereof, flames are not produced at an excess air factor of 1.6 or greater. In actual fact, since fuel and air are not ideally mixed in the premixing ignition burner, flame can be produced even at an excess air factor of 1.7, but in this case, the flame lifts off the burner and becomes unstable.

[9] Therefore, in the conventional fire hole part structure of a gas burner, in which flame is produced through the fire holes 121 defined on the flat upper surfaces of the fire hole pieces 120, since flame stabilizing means is not provided, the flame is likely to be unstable due to lifting. Also, as the load of the premixture, such as the flow amount or the flow rate, is increased, the length of the flame is also increased, and the flame is likely to come into direct contact with the heat exchanger arranged above the burner. In this case, as the temperature of the flame decreases, incomplete combustion can occur, generating a substantial amount of pollutants such as carbon monoxide, etc. Technical Solution

[10] Accordingly, an object of the present invention is to provide a fire hole part structure of a gas burner, which is constructed to be manufactured at a low cost, can improve flame stability, and can prevent incomplete combustion attributable to the length of flame.

Advantageous Effects

[11] Thanks to the features of the present invention, due to the fact that impingement injection of flame between adjoining fire hole pieces is made possible through the fire holes, which are defined in at least two directions inclined relative to a vertical direction, a flame holding characteristic can be improved, and excellent flame stability can be maintained even in combustion under a high load. Also, because the vertical length of the flame is decreased, incomplete combustion due to contact between the heat exchanger and flame can be prevented, the size of the burner can be reduced, and the combustion load can be increased.

[12] Moreover, by changing the shape or the arrangement of the fire hole pieces depending upon the desired performance or conditions, it is possible to provide a burner which can accomplish or further improve the above-described effects.

[13] Furthermore, by increasing the deformation strength of the fire hole piece through bending or curving the upper wall of the fire hole piece, even when a fire hole part is constructed such that the fire hole pieces are integrally connected with one another to constitute a single plate, deformation due to thermal stress can be reduced, and it is possible to provide a fire hole part structure having improved durability. Brief Description of the Drawings

[14] FIG. 1 is a perspective view illustrating a conventional fire hole part structure of a gas burner;

[15] FIG. 2 is a perspective view illustrating a fire hole part structure of a gas burner in accordance with a first embodiment of the present invention;

[16] FIG. 3 is cross-sectional view illustrating the main portion of the fire hole part stru cture shown in FIG. 2;

[17] FIG. 4 is a perspective view illustrating a fire hole part structure of a gas burner in accordance with a second embodiment of the present invention;

[18] FIG. 5 is a perspective view illustrating a fire hole part structure of a gas burner in accordance with a third embodiment of the present invention;

[19] FIG. 6 is a perspective view illustrating a fire hole part structure of a gas burner in accordance with a fourth embodiment of the present invention;

[20] FIG. 7 is a perspective view illustrating a fire hole part structure of a gas burner in accordance with a fifth embodiment of the present invention;

[21] FIG. 8 is a perspective view illustrating a fire hole part structure of a gas burner in accordance with a sixth embodiment of the present invention; and

[22] FIG. 9 is a perspective view illustrating a fire hole part structure of a gas burner in accordance with a seventh embodiment of the present invention. Best Mode for Carrying Out the Invention

[23] According to the present invention, there is provided a fire hole part structure provided to a premixing ignition burner which is installed to apply heat to the heat exchanger of a boiler, and including a plurality of fire hole pieces which are installed parallel to one another in mounting openings of a burner body and each of which is defined with a number of fire holes at regular intervals, wherein an upper wall of at least one of the fire hole pieces is bent or curved to extend in at least two directions, and the fire holes are defined through respective surface portions of the upper wall, which extend in different directions, to face different directions. Mode for the Invention

[24] The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description. Hereafter, a preferred embodiment of the present invention will be described with reference to the attached drawings.

[25] FIG. 2 is a perspective view illustrating a fire hole part structure of a gas burner in accordance with a first embodiment of the present invention, and FIG. 3 is cross- sectional view illustrating the main portion of the fire hole part structure shown in FIG. 2.

[26] Referring to FIGs. 2 and 3, in a fire hole part structure for a gas burner in accordance with a first embodiment of the present invention, fire hole pieces 20 are installed parallel to and adjacent to one another in a plurality of mounting openings 13 which are defined in the upper portion of a burner body 11.

[27] The burner body 11 is a conventional one. While not shown in the drawings, a manifold, in which fuel gas and air are mixed with each other, is coupled to the lower portion of the burner body 11. A gas supply pipe for supplying fuel and a blower for supplying air are coupled to the manifold. Since the burner body 11 has a conventional configuration, detailed description thereof will be omitted herein.

[28] A plurality of premixture accommodating spaces 14, which are separated by partition walls 12, is defined in the burner body 11 according to the capacity of the gas burner. Each premixture accommodating space 14 is opened upward, and the upper end thereof defines the mounting opening 13.

[29] Each fire hole piece 20 has an upper wall 21 which is bent along the center portion thereof in the lengthwise direction thereof, and defines a channel which is opened downward. The upper wall 21 is bent to have a wedge-shaped section which projects upward. The plurality of fire holes 23 is defined through surface portions which are divided by a bending line 24 in a manner such that the discharge directions of premixture through the fire holes 23 are inclined with respect to the vertical direction. Preferably, the fire holes 23 defined in both sides of the bending line 24 are arranged to be staggered with each other.

[30] Fastening holes 16 are defined in the burner body 11 adjacent to both lengthwise ends of the mounting openings 13. Support lips 27 to be received in the fastening holes 16 are formed on both lengthwise ends of the fire hole pieces 20. As fastening plates 15 are locked to the burner body 11 by bolts 17 in such a way as to press the support lips 27, the fire hole pieces 20 are fastened to the burner body 11. A plurality of grooves 25 is defined in the sidewalls of the fire hole pieces 20 to prevent distortion of the fire hole pieces 20 due to thermal stress and to promote cooling of the fire hole pieces 20.

[31] As described above, in the fire hole part structure according to the present invention, the upper wall 21 of each fire hole piece 20 is bent such that two inclined surface portions extending in different directions are formed, and the fire holes 23 are defined through the two inclined surface portions. Therefore, as shown in FIG. 3, the injection direction of the flame created through each fire hole 23 is inclined with respect to the vertical direction, and the two flames injected through the two facing fire holes 23 of adjoining fire hole pieces 20 interfere with each other, by which flame stabilizing means is formed.

[32] Accordingly, in the case of the fire hole pieces 20 according to the present invention, flame stability is improved compared to the conventional fire hole pieces formed of flat plates. Therefore, even when the air ratio of the flame or the load of a premixer is increased, flame lifting and resultant flame instability do not occur. Also, since the vertical length of the flame is shortened, the generation of incomplete combustion products, such as carbon monoxide, etc., which may be caused when the flame comes into direct contact with a heat exchanger, can be avoided. As a consequence, by adopting the fire hole part structure according to the present invention, the height of the combustion chamber of the burner can be decreased, and the thermal load per unit area can be increased, whereby high load combustion can be effected using a burner structure having a reduced size. Moreover, assuming that the width of the fire hole piece 20 and the interval between the fire holes 23 are the same, the length of the fire hole 23 is decreased by about half, and the number of fire holes 23 is doubled, whereby the above-described effects can be further improved.

[33] Moreover, due to the fact that the surface portions of the fire hole piece 20, which are bent along the bending line 24, are located at staggered positions, even when the fire holes 23 are densely defined through the fire hole pieces 20 to thus have a narrow interval, the flames created through adjoining fire holes 23 do not needlessly interfere or combine with each other. Therefore, it is possible to realize a burner structure which permits high load combustion and the combustion intensity of which can be adjusted. Also, for the same reason, while not shown in the drawings, it is possible for the facing fire holes 23 of two adjoining fire hole pieces 20 to be defined to be staggered with respect to each other.

[34] Meanwhile, although, in this embodiment, the fire hole piece 20 was illustrated as being bent to have a wedge-shaped section that projects upward, it is to be readily understood that the present invention is not limited to this concrete example. Therefore, the upper wall 21 of the fire hole piece 20 can be bent or curved to have various sections so that the fire holes 23 defined through the fire hole pieces 20 face at least two different directions. For example, as shown in FIG. 8, the upper wall 21 of the fire hole piece 20 can be bent downward toward the inside of the burner body 11 in a manner such that the upper surface of each fire hole piece 20 has a wedge-shaped section, similar to the above-described embodiment, but the bending line 24 is depressed downward, unlike the above-described embodiment.

[35] Also, in addition to the wedge-shaped section, as shown in FIG. 4, the upper wall

21 of each fire hole piece 20 can be curved upward in a manner such that the upper surface of each fire hole piece 20 has an arc-shaped section. The plurality of fire holes 23 is defined at two or more positions on the upper surface thereof to face directions which are inclined with respect to the vertical direction. Even in this sectional shape, similar to the wedge-shaped section described just above, the upper wall 21 can be curved downward toward the inside of the burner housing 11, as shown in FIG. 9.

[36] As the case may be, the fire hole pieces 20 may not have the same sectional shape.

For example, as shown in FIG. 5, fire hole pieces 20a each having a flat upper surface, similar to the conventional fire hole piece 120 and three-dimensional fire hole pieces 20, each having an upper wall 21 which is bent or curved, as described above, can be alternately arranged with each other. That is to say, differently shaped fire hole pieces 20 and 20a can be alternately arranged with each other. In the case where the fire hole pieces 20 and 20a are arranged as shown in FIG. 5, since both side portions of the flame, which is created through the flat type fire hole piece 20a, interfere with the flames which are created through two adjoining three-dimensional fire hole pieces 20, the flame holding characteristic and flame stability, as described above, can be improved, and impingement angle and the interval of flame can be easily adjusted within a wide range.

[37] Further, as shown in FIG. 5, in the case of the fire hole pieces 20b which are positioned on both side ends of the burner body 11, in order to avoid flame instability and incomplete combustion, which may occur due to direct contact of the flame with the burner body 11, it is preferred that only one surface portion of the two surface portions of the fire hole piece 20b which faces adjacent fire hole piece 20 or 20a be defined with the fire holes 23, and that the other surface portion of the two surface portions of the fire hole piece 20b, which faces the wall of the burner body 11, not be defined with the fire holes 23.

[38] In another embodiment of the fire hole pieces 20, which are positioned on both side ends of the burner body 11, as shown in FIG. 6, each fire hole piece 20 can be configured in a manner such that the surface portion, which faces the center of the fire hole part, is formed as an inclined surface 28, the surface portion, which faces away from the center of the fire hole part, is formed as a vertical surface 29 to be brought into contact with the wall of the burner body 11, and the fire holes 23 are defined only through the inclined surface 28.

[39] Further, although it was illustrated in the above-described embodiments that the respective fire hole pieces 20 are formed of individually separated plate members, as the case may be, as shown in FIG. 7, a single plate member can be bent so that the plurality of fire hole pieces 20 can be integrally connected with one another. Even in this case, since the upper surfaces 21 of the respective fire hole pieces 20 are bent or curved, the deformation strength of the fire hole part structure can be improved. Also, because a plurality of grooves 25 is defined in the sidewalls of the integrated fire hole pieces 20 to disperse thermal stress, even though the respective fire hole pieces 20 are not separated from one another, deformation due to thermal stress is decreased compared to the conventional fire hole part structure formed of the flat plates. Industrial Applicability

[40] The present invention can provide a fire hole part structure of a gas burner, which is constructed to be manufactured at low cost, can improve flame stability, and can prevent incomplete combustion due to the length of a flame.

Claims

[1] A fire hole part structure provided to a premixing ignition burner which is installed to apply heat to a heat exchanger of a boiler, and including a plurality of fire hole pieces (20) which are installed parallel to one another in mounting openings (13) of a burner body (11), and each of which has defined therein a number (plurality?) of fire holes (23) at regular intervals, wherein an upper wall (21) of at least one of the fire hole pieces (20) is bent or curved to extend in at least two directions, and the fire holes (23) are defined through respective surface portions of the upper wall (21), which extend in different directions, to face different directions.

[2] The fire hole part structure according to claim 1, wherein the upper wall (21) of the fire hole piece (20) has a wedge-shaped or an arc-shaped section which is concave or convex.

[3] The fire hole part structure according to claim 1 or 2, wherein, among the fire hole pieces (20), fire hole pieces (20b), which are installed in outermost mounting openings (13) of the burner body (11), are defined with the fire holes (23) only on respective surface portions thereof that face adjoining fire hole pieces (20).

[4] The fire hole part structure according to claim 1 or 2, wherein the fire holes (23) defined through the surface portions of each fire hole piece (20), which extend in different directions, are arranged to be staggered relative to each other.

[5] The fire hole part structure according to claim 1 or 2, wherein the fire hole part structure is formed by bending a single plate so that the fire hole pieces (20) are integrally connected with one another.