JP2006220314A - Flat gas burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat gas burner capable of reducing combustion noise and also reducing pressure loss at a burner port portion. <P>SOLUTION: In this flat gas burner having the burner port portion 3a on its upper end portion, a burner main body 1 composed of a pair of side plates 1a is provided with a lower mixing pipe portion, a distribution pipe portion 6 connected with the mixing pipe portion and longitudinally extending at an upper side of the mixing pipe portion, and a throttle portion 7 positioned between the distribution pipe portion 6 and the burner port portion 3 and narrowed in its width, and a straightening member 9 having four or more straightening plates 9a laterally arranged in parallel with each other, is mounted on the burner port portion 3. Lower end positions of the straightening plates 9a, 9a laterally adjacent to each other, have difference of elevation. One prescribed straightening plate 9a having a lowest lower end, is mounted on a position just above the throttle portion 7, and the larger a lateral distance from this straightening plate 9a, of the straightening plate 9a is, the higher a position of its lower end is determined. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flat gas burner used as a heat source for a hot water supply heat source machine or the like.

  In a heat source machine, in general, a plurality of flat gas burners having an elongated flame opening at the upper end thereof are arranged in parallel in a combustion casing forcibly supplying combustion air by a combustion fan. This type of flat gas burner is conventionally configured as follows. That is, a lower mixing tube portion and a mixing tube portion are formed on a burner body composed of a pair of side plates facing each other in the transverse direction, with the long direction of the flame mouth portion being the longitudinal direction and the short direction of the flame mouth portion being the lateral direction A distribution pipe part extending in the front-rear direction on the upper side of the mixing pipe part, and a throttle part having a narrower width between the distribution pipe part and the flame mouth part are formed. A rectifying member having a plurality of rectifying plates arranged side by side is mounted (see, for example, Patent Document 1).

  The rectifying member is provided to rectify the air-fuel mixture and eject it from the flame opening. Here, when the flat gas burner is disposed in the combustion casing forcibly supplying the combustion air by the combustion fan, turbulent flow is likely to occur due to the influence of the primary air forcibly flowing into the mixing tube portion. Therefore, in order to rectify the flow of the air-fuel mixture, the number of rectifying plates constituting the rectifying member needs to be four or more.

  By the way, the throttle part is formed in order to equalize the flow distribution in the front-rear direction of the air-fuel mixture supplied from the distribution pipe part to the flame mouth part, but the dynamic pressure is large at the lateral center of the throttle part. The flow rate also increases. An air-fuel mixture that has a large dynamic pressure and a large flow rate flows out from the central portion of the lateral width of the throttle portion between the rectifying plates positioned on the inner side in the lateral direction of the rectifying member. Therefore, the air-fuel mixture flowing in between the current plates located on the inner side in the lateral direction is jetted and burned above the flame opening without being sufficiently rectified, so that the stability of the flame is deteriorated and combustion noise is easily generated. Therefore, in the one described in Patent Document 1, rectification is performed by increasing the vertical length of the flame channel defined between a plurality of rectifying plates located on the inner side in the lateral direction among the rectifying plates constituting the rectifying member. In order to enhance the effect, the positions of the lower ends of the plurality of rectifying plates on the inner side in the horizontal direction are set lower than the positions of the lower ends of the rectifying plates on the outer side. For example, as shown in FIG. 4, when the rectifying member 9 is composed of five rectifying plates 9a, the positions of the lower ends of the three rectifying plates 9a located on the inner side in the lateral direction are both lowered, The position of the lower end of the current plate 9a is aligned.

However, in this way, when the positions of the lower ends of the plurality of rectifying plates 9a located on the inner side in the horizontal direction are aligned, the airflow between the inner rectifying plates 9a and 9a out of the air-fuel mixture flowing out from the lateral width central portion of the throttle portion 7 is increased. Due to the air-fuel mixture that could not enter the flame mouth channel, a vortex was generated near the lower ends of the rectifying plates 9a, 9a on both sides of the flame channel, and the inlet at the lower end of the flame channel was blocked from both sides by the vortex. It will come off. As a result, the rectifying action of the air-fuel mixture by the rectifying plate 9a is adversely affected by the vortex and the combustion noise cannot be sufficiently reduced. Further, the passage resistance of the air-fuel mixture flowing in the flame channel between the inner rectifying plates 9a and 9a is increased due to the influence of the vortex, and the inner rectifying plates 9a all extend downward, so The portion of the passage that guides the air-fuel mixture from the portion 7 to the laterally rectifying plate 9a is narrowed, and the passage resistance at this portion is also increased. As a result, the pressure loss at the flame port 3 becomes large, and in order to eject a required amount of air-fuel mixture from the flame port 3, it is necessary to increase the capacity of the combustion fan, which increases the cost.
JP-A-8-135929

  This invention makes it the subject to provide the flat burner which reduced the combustion noise and was able to also reduce the pressure loss in a flame opening part in view of the above point.

  In order to solve the above-mentioned problems, the present invention is a flat gas burner having an elongate-shaped flame opening portion opened at the upper end, the longitudinal direction of the flame opening portion being the longitudinal direction, and the short direction of the flame opening portion. Is a burner body composed of a pair of side plates facing each other in the transverse direction, a lower mixing tube portion, a distribution tube portion that is continuous with the mixing tube portion and extends in the front-rear direction above the mixing tube portion; A narrowing portion having a narrower width between the distribution pipe portion and the flame opening portion, and a flow straightening member having four or more flow straightening plates arranged side by side in the flame opening portion. , The height difference is given to the position of the lower end of the rectifying plate adjacent in the horizontal direction, and the predetermined one rectifying plate having the lowest position of the lower end is arranged immediately above the throttle part, and the horizontal direction from this rectifying plate A rectifying plate having a larger distance is characterized in that the position of its lower end is higher.

  According to the present invention, the air-fuel mixture from the throttle portion is smoothly distributed in the lateral direction by the predetermined rectifying plate located immediately above the throttle portion, and the dynamic pressure flowing out from the central width of the throttle portion is large and the flow rate is large. The flow of the air-fuel mixture is also spread laterally, and the flow becomes gentle. Since the position of the lower end of the rectifying plate increases as the distance from the predetermined rectifying plate increases in the lateral direction, the area of the portion serving as a passage for the air-fuel mixture distributed in the horizontal direction is ensured, and the flame between the respective rectifying plates is secured. The air-fuel mixture flows smoothly into the mouth channel. As a result, the pressure loss at the flame port is reduced, and the required amount of air-fuel mixture can be ejected from the flame port without increasing the ability of the combustion fan to supply primary air to the mixing tube of the burner body. .

  Further, since the air-fuel mixture smoothly flows into the flame channel between the current plates, the generation of vortex near the lower end of the current plate is suppressed. However, a mixture of a large dynamic pressure flowing out from the central portion of the width of the throttle portion and a large flow rate hits the lower end of the predetermined rectifying plate located immediately above the throttle portion, so that some eddy current is generated in the vicinity thereof. However, since the position of the lower end of the rectifying plate adjacent to the predetermined rectifying plate is higher than the position of the lower end of the predetermined rectifying plate, the lower end of the flame channel between the predetermined rectifying plate and the rectifying plate adjacent thereto is located. The inlet portion is not blocked by the vortex, and the air-fuel mixture flows smoothly into the flame opening channel. As a result, the rectifying action of the air-fuel mixture by each rectifying plate is exhibited without being adversely affected by the eddy current, the flame is stabilized, and the combustion noise is reduced.

  By the way, it is also possible to form the constricted part by shifting one side in the lateral direction, and the position of the lower end of the rectifying plate can be increased in order from one outermost rectifying plate in the lateral direction to the other outermost rectifying plate in the horizontal direction. It is. However, in this case, the burner body has an asymmetric shape with respect to the center of the lateral width, and the production becomes troublesome. Therefore, it is desirable that the narrowed portion is formed so that the center of the width thereof coincides with the center of the width of the burner body. In this case, if the number of rectifying plates constituting the rectifying member is an even number of 4 or more, the two inner rectifying plates are arranged on both sides of the horizontal width center of the burner body. According to the present invention, one of the two rectifying plates is used as the predetermined rectifying plate, and the position of the lower end thereof is the lowest. However, this can ensure symmetry with respect to the horizontal width center of the burner body. This makes it difficult to equalize the lateral distribution of the amount of air-fuel mixture ejected from the flame port. On the other hand, if the number of the rectifying plates constituting the rectifying member is an odd number of 5 or more, the rectifying plates arranged at the center in the horizontal direction coincide with the horizontal width center of the burner body. Accordingly, by making the position of the lower end of the current plate the lowest, it is possible to ensure symmetry with respect to the width center of the burner body.

  FIG. 1 shows a lean combustion type flat gas burner used as a heat source of a hot water supply heat source machine. Although not shown, the heat source device includes a combustion casing that forcibly supplies combustion air by a combustion fan, and a plurality of flat gas burners are arranged in parallel in the combustion casing.

  The flat gas burner shown in FIG. 1 includes a burner body 1 and a burner cap 2 that covers the upper part of the burner body 1. At the upper end of the burner body 1 is formed an elongated flame opening 3 that opens upward, and the burner cap 2 forms slit-like sleeve flame openings 4 located on both sides of the flame opening 3. Has been. Then, an air-fuel mixture having a leaner fuel ratio than the stoichiometric air-fuel ratio (air-rich air-fuel mixture) is ejected from the flame port 3, and an air-fuel mixture having a higher fuel ratio than the stoichiometric air-fuel ratio (gas-rich air-fuel mixture) is The generation of NOx can be reduced by ejecting from 4 and performing so-called light and dark combustion.

  Hereinafter, the configuration of the flat gas burner will be described with the longitudinal direction of the flame port 3 as the front-rear direction and the short direction of the flame port 3 as the horizontal direction. As shown in FIGS. 2 and 3, the burner body 1 is composed of a pair of side plates 1a and 1a facing each other in the lateral direction. The both side plates 1a and 1a are formed of a single continuous plate, and the burner body 1 is formed by folding this plate into a palm-joined state at a fold line that becomes the lower edge of the burner body 1. Then, by pressing each side plate 1 a, the burner body 1 is connected to the flame port 3 at the upper end, the lower mixing tube 5, and the mixing tube 5, and extends in the front-rear direction above the mixing tube 5. An existing distribution pipe part 6 and a narrowed part 7 having a narrower lateral width between the distribution pipe part 6 and the flame port part 3 are formed.

  The mixing tube portion 5 extends forward from an opening end 5 a located at the lower rear edge of the burner body 1, and its front end portion is bent upward and communicates with the distribution tube portion 6. In addition, at the rear part of the burner main body 1, a mixing pipe part 8 for a sleeve fire is formed between the mixing pipe part 5 and the distribution pipe part 6. The mixing tube portion 8 terminates slightly forward from the opening end 8a located at the rear edge of the burner body 1, and a plurality of vent holes 8b are formed on the side surface of the front portion. Both the mixing pipe portions 5 and 8 are supplied with fuel gas from different gas nozzles (not shown) facing the open ends 5a and 8a, and also supplied with air (primary air) from the combustion fan. The fuel gas and the primary air are mixed in each of the mixing pipe portions 5 and 8, and an air-fuel mixture is generated. Here, the opening end 5a of the mixing tube portion 5 is formed to be relatively large. Therefore, in the mixing tube portion 5, an inflow amount of primary air increases and an air-rich mixture is generated. On the other hand, the opening end 8a of the sleeve-fired mixing pipe portion 8 is formed to be relatively small. Therefore, in the mixing pipe portion 8, the amount of inflow of primary air is reduced and a gas-rich mixture is generated.

  The burner cap 2 is composed of a pair of side plates 2a, 2a that are placed on the outside of the pair of side plates 1a, 1a of the burner body 1, and a plurality of bridge portions 2b that connect the side plates 2a, 2a at their upper edges. Yes. Then, between the side plate 1a of the burner body 1 and the side plate 2a of the burner cap 2, the sleeve flame outlet 4 at the upper end and the mixing tube portion 8 for the sleeve fire are disposed outside the burner body 1 through the vent hole 8b. A passage for guiding the flowing air-fuel mixture to the sleeve flame opening 4 is formed. The side plate 2a of the burner cap 2 is in contact with the outer surface of the intermediate portion in the front-rear direction of the distribution pipe portion 6 of the burner body 1, and a recess 2c that distributes the flow of the air-fuel mixture from the vent hole 8a in the front-rear direction. A plurality of longitudinally recessed portions 2d are formed in contact with the outer surface of the flame mouth portion 3 of the burner body 1 and partition the sleeve flame mouth portion 4 into a plurality of front and rear areas.

  A rectifying member 9 is mounted in the flame opening 3 of the burner body 1. As clearly shown in FIG. 3, the rectifying member 9 has five rectifying plates 9 a arranged side by side in the lateral direction, and a narrow flame opening channel is defined between the rectifying plates 9 a and 9 a. . These baffle plates 9a overlap with each other without crevice at a plurality of crushing portions 9b at the front and back of the rectifying plate 9a, and the flame channel is divided into a plurality of front and rear areas. Note that the bridge portion 2b of the burner cap 2 is located immediately above the crushed portion 9b. Further, a narrowed portion 3a is formed in the flame port portion 3 of the burner body 1 so as to be positioned at an intermediate portion in the vertical direction and sandwich the rectifying member 9 from both lateral sides. Thus, a blind gap 3b is defined between the portion of the side plate 1a on the upper side of the narrowed portion 3a and the outermost rectifying plate 9a of the rectifying member 9 so that no air-fuel mixture flows.

  The air-fuel mixture generated in the mixing tube portion 5 of the burner body 1 flows to the flame mouth portion 3 through the distribution tube portion 6 and the throttle portion 7, and passes through the flame mouth channel between the rectifying plates 9a and 9a. It spouts above the mouth 3 and burns. The lateral width of the throttle portion 7 gradually increases from the front portion near the downstream end of the mixing pipe portion 5 toward the rear, and the flow rate distribution in the front-rear direction of the air-fuel mixture flowing into the flame port portion 3 is equalized. By the way, the narrowed portion 7 can be formed by being offset to one side in the horizontal direction of the burner main body 1, but in this case, the burner main body 1 has an asymmetric shape with respect to the center of the horizontal width, and the production becomes troublesome. Therefore, in the present embodiment, the narrowed portion 7 is formed so that the center of the width thereof coincides with the center of the width of the burner body 1.

  In this case, of the five rectifying plates 9 a of the rectifying member 9, one rectifying plate 9 a disposed at the center in the horizontal direction is positioned directly above the center of the lateral width of the aperture portion 7. And in this embodiment, the position of the lower end of this center baffle plate 9a is made the lowest, and the position of the lower end becomes high, so that the baffle plate 9a with the large lateral distance from this baffle plate 9a is large. Accordingly, as a matter of course, a height difference is given to the position of the lower end of the current plate 9a, 9a adjacent in the lateral direction.

  When the position of the lower end of each rectifying plate 9a is set in this way, the air-fuel mixture from the restricting portion 7 is smoothly distributed in the lateral direction by the central rectifying plate 9a located immediately above the restricting portion 7, and the restricting portion 7 The flow of the air-fuel mixture with a large dynamic pressure flowing out from the central portion of the lateral width is widened in the lateral direction, and the flow becomes gentle. Since the position of the lower end of the rectifying plate 9a is increased as the distance from the central rectifying plate 9a is increased in the lateral direction, the area of the portion serving as the passage of the air-fuel mixture distributed in the lateral direction is ensured, and each rectifying plate 9a is secured. , 9a smoothly flows into the flame channel. As a result, the pressure loss in the flame port 3 is reduced, and a required amount of air-fuel mixture can be ejected from the flame port 3 without increasing the capacity of the combustion fan.

  Further, since the air-fuel mixture smoothly flows into the flame channel between the current plates 9a and 9a, the generation of vortex near the lower end of the current plate 9a is suppressed. However, since the air pressure flowing from the central portion of the width of the narrowed portion 7 is large and the air-fuel mixture with a large flow rate hits the lower end of the central rectifying plate 9a, some eddy current is generated in the vicinity thereof. However, since the position of the lower end of the rectifying plate 9a adjacent to the central rectifying plate 9a is higher than the position of the lower end of the central rectifying plate 9a, the flame port between the central rectifying plate 9a and the rectifying plate 9a adjacent thereto. The inlet at the lower end of the flow path is not blocked by the vortex, and the air-fuel mixture flows smoothly into the flame opening flow path. As a result, the rectifying action of the air-fuel mixture by each rectifying plate 9a is exhibited without being adversely affected by the vortex flow, the flame is stabilized, and the combustion noise is reduced.

  A flat gas burner (the present invention burner) in which the dimensions of L1 to L4 in FIG. 3 are L1 = 10 mm, L2 = 7.6 mm, L3 = 3.8 mm, and L4 = 20.3 mm, and L1 to L4 in FIG. When the combustion test was performed using the burner of the comparative example shown in FIG. 4 in which the dimensions of the parts corresponding to these parts were the same as those of the burner of the present invention, and the combustion noise was measured, the result shown in FIG. 5 was obtained. The comparative example burner is obtained by lowering the positions of the lower ends of the three inner rectifying plates 9 a among the five rectifying plates 9 a constituting the rectifying member 9. In the burner of the present invention, the length of the rectifying plate 9a is 19 mm for the central rectifying plate 9a, 17mm for the outer rectifying plate 9a, and 15mm for the outermost rectifying plate 9a. Then, the three inner current plates 9a are 19 mm, and the outermost current plate 9a is 17 mm. In addition, the combustion test was performed by setting one burner on a testing machine and burning it in an open atmosphere. An air-fuel mixture with a fuel gas amount (heating value conversion flow rate) of 1900 kcal / h and an excess air ratio of 1.4 is supplied to the flame port 3, and a combustion gas amount of 800 kcal / h is supplied to the sleeve flame port 4. h, an air-fuel mixture with an excess air ratio of 0.5 was supplied.

  FIG. 5 shows the sound pressure level of combustion noise in each band through a band-pass filter defined in the 1/3 octave standard. The a line is the combustion noise of the burner of the present invention, and the b line is a comparative burner. Is the combustion noise. Further, the all-pass (total sound pressure when not passing through the band-pass filter) was measured and found to be 47.9 dB for the burner of the present invention and 48.8 dB for the comparative burner. Therefore, it can be seen that the combustion noise is smaller in the burner of the present invention.

  As described above, the embodiment has been described in which the throttle portion 7 is formed such that the center of the width thereof coincides with the center of the width of the burner body 1 and the number of the rectifying plates 9a constituting the rectifying member 9 is five. The number of 9a may be an odd number of 7 or more. In this case as well, the position of the lower end of one current plate arranged at the center in the horizontal direction is made the lowest. Further, the number of the rectifying plates 9a can be an even number of 4 or more. However, when the narrowed portion 7 is formed so that the center of its width coincides with the center of the width of the burner body 1, if the number of the rectifying plates 9 a is an even number of 4 or more, both sides of the center of the width of the burner body 1 are provided. Since the two inner current plates are arranged, it is necessary to make the position of the lower end of one of the two current plates the lowest. As a result, the symmetry about the center of the width of the burner body 1 cannot be ensured, and it becomes difficult to equalize the lateral distribution of the amount of air-fuel mixture ejected from the flame opening 3. Therefore, when the narrowed portion 7 is formed so that the center of the width thereof coincides with the center of the width of the burner body 1, it is desirable that the number of the rectifying plates 9a is an odd number of 5 or more.

  Moreover, although the flat burner of the said embodiment is a concentration combustion type burner provided with the burner cap 2, this invention is applicable similarly to the flat burner which does not have the burner cap 2, and is not a concentration combustion type.

The perspective view which shows the flat gas burner of embodiment of this invention. The perspective view of the state which removed the burner cap of the flat gas burner of FIG. Sectional drawing cut | disconnected by the III-III line | wire of FIG. Sectional drawing corresponding to FIG. 3 of the gas burner of a comparative example. The graph which shows the measurement result of combustion noise.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Burner main body, 1a ... Side plate, 3 ... Flame opening part, 5 ... Mixing pipe part, 6 ... Distribution pipe part, 7 ... Restriction part, 9 ... Rectification member, 9a ... Rectification board.

Claims (2)

A flat gas burner having an elongated flame opening at the upper end that opens upward, with the long direction of the flame opening being the front-rear direction and the short direction of the flame opening being the horizontal direction, A burner body composed of side plates, a lower mixing pipe section, a distribution pipe section connected to the mixing pipe section and extending in the front-rear direction on the upper side of the mixing pipe section, and between the distribution pipe section and the flame outlet section A narrowed throttle part is formed, and a rectifying member having four or more rectifying plates arranged side by side in the lateral direction is mounted in the flame opening part.
A difference in height is added to the position of the lower end of the current plate adjacent in the horizontal direction, and a predetermined single current plate having the lowest position of the lower end is disposed immediately above the throttle portion, and the horizontal distance from this current plate is A flat gas burner characterized in that the position of the lower end of the larger rectifying plate is higher.   The throttle portion is formed such that the center of the width of the throttle portion coincides with the center of the width of the burner body, and the rectifying member has an odd number of five or more rectifying plates, and among these rectifying plates, The flat gas burner according to claim 1, wherein the position of the lower end of the current plate arranged in the center in the horizontal direction is the lowest.

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