JP7609658B2 - Combustion equipment - Google Patents

Description

The present invention relates to a combustion device that includes a combustion housing, in which multiple burners, each of which has a flame port at the top end for ejecting an air-fuel mixture and is elongated in the front-to-rear direction, are arranged side by side with gaps in the horizontal direction in the combustion chamber, and secondary air is supplied from below into the gaps between each burner.

Conventionally, in this type of combustion device, a fire-transfer plate that prevents the secondary air from rising is generally placed in the gap between each burner, near the upper end of the front-to-rear portion that coincides with one of the front and rear ends of the flame port formation area of each burner (see Patent Document 1). When a fire-transfer plate is placed, secondary air has difficulty flowing directly above the fire-transfer plate, so that a part of the mixture ejected from the flame port of one horizontally adjacent burner and a part of the mixture ejected from the flame port of the other burner remain directly above the fire-transfer plate, facilitating the transfer of fire from one burner to the other burner.

However, if the clearance between the outer surface of the burner and the side edge of the flame-transfer plate becomes wide due to an error in the width of the burner or the flame-transfer plate, secondary air will flow upward through the clearance and blow away the air-fuel mixture that is stagnating directly above the flame-transfer plate, resulting in a deterioration in flame-transfer performance.

Japanese Patent Application Publication No. 5-280715

In view of the above, the present invention aims to provide a combustion device that can reliably prevent deterioration of flame-transfer performance.

In order to solve the above problems, the present invention provides a combustion device that includes a combustion housing, in which multiple burners that are longitudinal in the front-rear direction and have a flame port at the top end that ejects the air-fuel mixture are arranged side by side with gaps in the horizontal direction in the combustion chamber, and secondary air is supplied to the gaps between each burner from below. In the gaps between each burner, a fire-stop plate that prevents the secondary air from rising is placed near the upper end of the front-rear portion that matches one of the front and rear ends of the flame port formation area of each burner, and is characterized in that a bulge is provided on the outer surface of the burner at a front-rear position that matches the fire-stop plate and on a portion located above the fire-stop plate, which bulges outward in the horizontal direction more than the portion of the outer surface of the burner adjacent to that portion in the front-rear direction.

According to the present invention, even if the clearance between the outer surface of the burner and the side edge of the fire-transfer plate becomes somewhat wider due to an error in the width of the burner or the fire-transfer plate, the bulging portion imparts a large lateral component to the flow of secondary air that flows through the clearance toward the upper part of the fire-transfer plate, and the upward momentum of the secondary air is weakened. Therefore, the air-fuel mixture that remains directly above the fire-transfer plate can be effectively prevented from being blown away by the secondary air. Furthermore, in the part that matches the fire-transfer plate, the bulging portion narrows the gap between the flame port of one burner and the flame port of the other burner that are adjacent in the horizontal direction, making it easier for fire to transfer between these flame ports. This, combined with the fact that the blowing away of the air-fuel mixture that remains directly above the fire-transfer plate by the secondary air can be effectively prevented, ensures that the fire-transfer performance is prevented from deteriorating. In addition, since the part of the outer surface of the burner adjacent to the bulging portion in the front-rear direction does not bulge outward in the horizontal direction, sufficient secondary air is supplied to the air-fuel mixture that ejects from the flame port, and the combustibility does not deteriorate.

1 is a perspective view of a combustion device according to an embodiment of the present invention; FIG. 2 is a cross-sectional side view taken along line II-II in FIG. FIG. 3 is a cross-sectional plan view taken along line III-III in FIG. 2 . FIG. 4 is an enlarged cross-sectional view of a main portion taken along line IV-IV in FIG. FIG. 2 is a perspective view of a burner provided in the combustion device according to the embodiment. 6 is a cross-sectional view of the burner taken along line VI-VI in FIG. 5 . FIG. 4 is a perspective view of a burner retainer plate provided in a combustion housing of the combustion device according to the embodiment.

Referring to Figures 1 to 3, the combustion device according to the embodiment of the present invention comprises a combustion housing 1, a plurality of burners 2 (six in this embodiment) arranged side by side in the lower part of the combustion housing 1 with horizontal gaps between them, which are elongated in the front-rear direction, a gas manifold 3 that supplies fuel gas to the burners 2, and a heat exchanger 4 that is arranged in the upper part of the combustion housing 1 and is heated by the combustion gas from the burners 2. An upstream water supply pipe 41 and a downstream hot water outlet pipe 42 are connected to the heat exchanger 4. A valve unit 5 that controls the supply of fuel gas is connected to the gas manifold 3.

Referring to Figures 5 and 6, the burner 2 is provided with a burner body 21 having a pair of side plates 21a, 21a facing each other in the lateral direction, and a burner cap 22 having a pair of side plates 22a, 22a covering the burner body 21 from both lateral sides. At the upper end of the burner 2, a main flame port 23a located between the upper ends of the side plates 21a, 21a of the burner body 21 and a sleeve flame port 23b defined between the upper ends of each side plate 21a of the burner body 21 and the upper ends of each side plate 22a of the burner cap 22 are provided as flame ports 23 for ejecting the mixture. Note that the main flame ports 23a are formed in a plurality at intervals in the front-rear direction on the upper plate portion 21b connecting the upper ends of the side plates 21a, 21a of the burner body 21.

The burner body 21 is provided with a lower mixing tube section 24 that extends rearward from an inlet 24a at the front end, and a main mixture passage 25 that extends upward while widening in the front-to-rear direction from the rear end of the mixing tube section 24. The mixture of fuel gas and primary air flowing in from the inlet 24a is guided to the main flame port 23a via the mixing tube section 24 and the main mixture passage 25.

Between each side plate 21a of the burner body 21 and each side plate 22a of the burner cap 22, a sleeve fire mixture passage 26 connected to the sleeve fire nozzle 23b is provided. In addition, each side plate 21a of the burner body 21 is located above the overlapping portion of the lower part of each side plate 22a of the burner cap 22, and a plurality of vent holes 26a are formed at intervals in the front-rear direction to connect the main mixture passage 25 and the sleeve fire mixture passage 26. The mixture diverted from the main mixture passage 25 through these vent holes 26a is supplied to the sleeve fire nozzle 23b through the sleeve fire mixture passage 26, and the sleeve fire formed on the sleeve fire nozzle 23b maintains the main flame formed on the main flame nozzle 23a.

In addition, grooves 27 are formed in each side plate 22a of the burner cap 22, positioned above the vents 26a and recessed laterally inward. This allows the mixture flowing from the vents 26a into the sleeve fire mixture passage 26 to be distributed in the front-rear direction below the grooves 27, ensuring uniformity in the front-rear distribution of the mixture ejected from the sleeve fire port 23b. The burner cap 22 has bridges 22b that connect the upper ends of both side plates 22a, 22a at multiple points in the front and rear.

The combustion housing 1 is composed of a front side plate 11 that covers the front portion of the combustion housing 1 located above the gas manifold 3, side plates 12, 12 on both sides in the lateral direction, a rear side plate 13, and a bottom plate 14. In addition, heat shields 15, 16, 17 are provided so as to face the inner surfaces of the front, lateral, and rear side plates 11, 12, 13. Furthermore, an electrode part 7 having an ignition electrode 71 for igniting the burner 2 and a flame rod 72 for flame detection of the burner 2 is attached to the front side plate 11.

Also, on the inside of the rear side plate 13, a burner pressing plate 18 shown in FIG. 7 is arranged, which has a pressing piece portion 181 at its lower end that engages with a recessed portion 28 formed in the lower rear edge of the burner body 21. In order to position each burner 2, the pressing piece portion 181 has a number of slit-shaped notches 182 formed corresponding to the number of burners 2 into which the rear edge portion of the burner body 21 recessed forward by the recessed portion 28 is inserted.

The front part of the bottom plate 14 is formed with an upright plate section 141 that rises upward at the rear position of the gas manifold 3, and an upper plate section 142 that bends forward from the upper end of the upright plate section 141 and reaches the front side plate 11. The upright plate section 141 has an opening 143 that faces the inlet 24a of each burner 2. In addition, a ventilation adjustment plate 6 is arranged on the front side of the upright plate section 141. The ventilation adjustment plate 6 has a plurality of openings 61 that face the inlet 24a of each burner 2 and through which fuel gas and primary air pass, corresponding to the plurality of burners 2. The ventilation adjustment plate 6 is fixed to the upright plate section 141 with a screw 62 at the upper end of its horizontal center section.

The bottom plate 14 has multiple upward recesses 144 that sandwich the lower edge of each burner 2 from both sides in the lateral direction, and also has multiple small holes 145 formed therein. In addition, a second upright plate portion 146 that rises along the inner surface of the front side plate 11 is formed at the front end of the upper plate portion 142. The upper end of the second upright plate portion 146 has multiple bent claw portions 147 that are inserted into the gap between the front ends of adjacent burners 2, 2 to position the front ends of the burners 2 in the lateral direction.

An exhaust fan 8 is connected to the upper end of the combustion box 1 via an exhaust hood 81. A fan motor 82 is attached to the exhaust fan 8. The combustion gas that has passed through the heat exchanger 4 is sucked into the exhaust fan 8, and the combustion gas is discharged to the outside through an exhaust pipe (not shown) connected to the outlet 83 of the exhaust fan 8. In addition, combustion air is supplied to each burner 2 by the suction force of the exhaust fan 8. That is, air sucked from the inlet 24a through each opening 61 of the ventilation adjustment plate 6 and each opening 143 of the upright plate portion 141 is supplied to each burner 2 as primary air for combustion, and air sucked from the small hole 145 is supplied to the gap between each burner 2, 2 from below as secondary air for combustion.

When combustion starts, it is necessary to transfer the flame from the burner 2 facing the ignition electrode 71 to the other burner 2. Therefore, a flame transfer plate 19 that prevents the secondary air from rising is provided in the gap between each burner 2, 2, located near the upper end of the front-rear direction part that coincides with the rear end of the flame port forming area of each burner 2. This makes it difficult for secondary air to flow directly above the flame transfer plate 19, so that when the flame transfers, part of the mixture ejected from the flame port 23 of one adjacent burner 2 and part of the mixture ejected from the flame port 23 of the other burner 2 remain directly above the flame transfer plate 19, facilitating the flame transfer from one burner 2 to the other burner 2.

As shown in Figure 4, the side edge of the fire-transfer plate 19 is inserted into the groove 27 formed in the vertical position that matches the fire-transfer plate 19 of each side plate 22a of the burner cap 22, which is the outer surface of the burner 2. With this, even if the clearance between the side of the groove 27 and the side edge of the fire-transfer plate 19 becomes somewhat wider due to an error in the width of the burner 2 or the fire-transfer plate 19, the flow path of the secondary air that runs from below to above the fire-transfer plate 19 through the clearance bends laterally within the groove 27, so that the air flow resistance increases and the flow rate of the secondary air flowing above the fire-transfer plate 19 does not increase significantly.

The front end of the flame-transfer plate 19 is provided with a tongue portion 19a that extends diagonally downward and forward. The reason for providing the tongue portion 19a is as follows. Near the front end of the flame-transfer plate 19, a vortex occurs in the flow of secondary air going upward. When this vortex reaches the upper end of the burner 2, the vortex adversely affects the combustibility of the burner 2. When the tongue portion 19a is provided, a vortex occurs in the flow of secondary air going upward near the front end of the tongue portion 19a. Therefore, the position where the vortex occurs is shifted downward, making it difficult for the vortex to reach the upper end of the burner 2, and it is possible to prevent the vortex from deteriorating the combustibility of the burner 2. In addition, in order to extend the tongue portion 19a below the groove portion 27, the width of the tongue portion 19a is narrower than the main body of the flame-transfer plate 19 whose side edge is inserted into the groove portion 27.

However, the depth of the groove 27 recessed laterally inward cannot be made too deep to prevent the airflow resistance of the secondary air mixture passage 26 from becoming excessive. Therefore, it is difficult to sufficiently increase the airflow resistance of the secondary air within the groove 27.

Therefore, in this embodiment, a bulge 29 is provided on each side plate 22a of the burner cap 22, which is the outer surface of the burner 2, at a front-rear position that matches the fire-transfer plate 19 and above the groove 27, i.e., on the part located above the fire-transfer plate 19, which bulges outward in the lateral direction from the part of the outer surface of the burner adjacent to the front-rear direction of the said part. This provides a large lateral component to the flow of secondary air above the fire-transfer plate 19 by the bulge 29, thereby weakening the upward momentum of the secondary air. Therefore, even if the flow resistance of the secondary air in the groove 27 cannot be sufficiently increased, it is possible to effectively prevent the mixed gas remaining directly above the fire-transfer plate 19 from being blown away by the secondary air. Furthermore, in the area that meets the flame transfer plate 19, the gap between the sleeve flame nozzle 23b of one burner 2 and the sleeve flame nozzle 23b of the other burner 2 that are adjacent in the horizontal direction is narrowed by the bulge 29, making it easier for flame to transfer between these sleeve flame nozzles 23b, 23b. This, combined with the fact that the secondary air can effectively suppress the blowing away of the air-fuel mixture that remains directly above the flame transfer plate 19, reliably prevents deterioration of flame transfer performance.

In addition, since the portion of the outer surface of the burner adjacent to the bulging portion 29 in the front-rear direction does not bulge outward in the lateral direction, sufficient secondary air is supplied to the mixture gas ejected from the flame port 23, and the combustibility is not deteriorated. In addition, in this embodiment, as shown in FIG. 7, the flame transfer plate 19 is integrally formed at the upper end of the burner pressing plate 18. This allows the number of parts to be reduced and costs to be reduced. Furthermore, in this embodiment, a pair of bulging portions 29 are formed symmetrically in the front-rear direction on each side plate 22a of the burner cap 22. As a result, even if the burner cap 22 is attached to the burner body 21 in the front-rear direction inverted, the bulging portion 29 will be present in the front-rear direction portion that matches the flame transfer plate 19. Therefore, the burner cap 22 can be attached to the burner body 21 without worrying about the front-rear direction, and the assembly workability of the burner cap 22 is improved.

Although the embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited thereto. For example, the above embodiment applies the present invention to a combustion device in which secondary air is supplied from below to the gaps between each burner 2, 2 by the suction force of the exhaust fan 8, but the present invention can also be applied to a combustion device in which an air supply chamber to which air is supplied from a fan is provided below the bottom plate 14 of the combustion housing 1, and secondary air is supplied from below to the gaps between each burner 2, 2 through the air supply chamber.

It is also possible for the burner 2 not to have a burner cap 22. In this case, a bulge that bulges outward laterally from the part of the burner outer surface adjacent to the part in the front-rear direction of the side plate 21a of the burner body 21, which is the outer surface of the burner 2, can be provided at a front-rear position that matches the fire transfer plate 19 and is located above the fire transfer plate 19. Furthermore, it is also possible to place the fire transfer plate 19 in the gap between each burner 2, 2, near the upper end of the front-rear portion that matches the front end of the flame port formation area of each burner 2.

1...combustion box, 19...fire transfer plate, 2...burner, 23...flame mouth, 29...bulge.

Claims (1)

A combustion device comprising a combustion housing, in which a plurality of burners each having a flame port at an upper end for ejecting an air-fuel mixture and elongated in the front-rear direction are arranged side by side with gaps in the lateral direction, and secondary air is supplied from below into the gaps between each burner,
In the case where a flame-transfer plate is disposed in the gap between each burner near the upper end of the front-rear direction portion that coincides with one of the front and rear ends of the flame port forming region of each burner, and prevents the secondary air from rising,
A combustion device characterized in that a bulging portion is provided on the outer surface of a burner at a front-to-rear position that coincides with a flame-transfer plate and is located above the flame-transfer plate, the bulging portion bulging outward laterally more than the portion of the outer surface of the burner adjacent to the front-to-rear position of the burner.

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