JPH0616283Y2 - Combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a combustor having a structure in which a combustion air is forcibly supplied by a fan, and in particular, a gas combustor improved to reduce combustion noise. It is about.

[Conventional technology]

FIGS. 5 and 6 show a conventional example of this type of gas combustor, and FIG. 5 is a perspective view in which the vicinity of a gas burner is broken and drawn.
FIG. 6 is a sectional view.

A plurality of gas burners 3 are arranged in the burner case 1, and a large number of flame holes 3a are arranged in the longitudinal direction thereof. 2 is a burner mounting plate fixed to the burner case 1. The gas burner 3 is fixed by inserting the tip portion in the longitudinal direction thereof into the burner mounting plate.

Combustion air is supplied from below the burner case 1 by a fan (not shown), and the inside of the burner case 1 is ventilated upward.

In order to install the gas burner 3 in the burner case 1,
The cross-sectional shape of the burner case near the gas burner mounting portion is
The upstream side (lower side in the figure) of the stepped portion 1a shown in the figure is larger than the downstream side (upper side).

[Problems to be solved by the device]

As shown in FIG. 6, the gas fuel mixed with the primary air is jetted upward from the flame holes 3a of the gas burner 3 and burned,
Secondary air is provided to form flame 9.

In recent years, combustion appliances have been downsized due to the development of high-load combustion technology, but with this, there has been a problem that combustion noise increases.

Of the combustion noises, those caused by the flame lift phenomenon have been dealt with by providing a flame holding mechanism, but effective prevention techniques have been developed for the combustion noises caused by the turbulence of the secondary air flow described below. Absent.

In FIG. 6, the secondary air flows from the lower side to the upper side, and a part of the secondary air flows as shown by an arrow a in the burner case stepped portion 1.
In addition, the other part hits the burner mounting plate 2 as shown by the arrow b to change the flow direction and locally generate a turbulent flow.

The secondary air flow described above can be expected to flow between the burner case 1 and the flame 9 to cool the burner case 1, but it is not desirable to generate turbulence as described above. The reason is that the combustion state of the flame located near the turbulent flow becomes unstable and combustion noise is generated.

The present invention has been made in view of the above circumstances, and provides a gas combustor having a simple structure capable of preventing turbulence of a secondary air flow and stabilizing a flame, and contributes to reduction of combustion noise. To aim.

[Means for Solving the Problems]

The basic principle of the present invention, which was created to achieve the above-mentioned object, is that the secondary air flow can be diverted near the gas burner by an obstacle as shown by arrows a and b in FIG. It is something that should not be done.

Based on the above-mentioned principle, 2
In order to bring the secondary air flow into the rectifying state, the combustion apparatus of the present invention causes the burner mounting plate supporting the longitudinal end of the gas burner to serve as the secondary air flow rectifying plate.
The burner mounting plates are arranged on the downstream side (narrow side of the flow passage cross section) of the stepped portion of the burner case so that the gas flow passage near the gas burner does not sharply narrow toward the downstream side. Keep it constant.

Here, in the vicinity of the gas burner, the turbulence of the secondary air flow is flame 9
Area that may affect the shape of the.

[Action]

The gas burner mounting portion of the burner case 1 has a large cross-sectional shape for accommodating the gas burner, and therefore, the stepped portion 1a is formed on the downstream side of the gas burner mounting portion to narrow the cross-sectional shape. According to the above configuration, the burner mounting plate arranged in alignment with a portion having a smaller cross-sectional shape on the downstream side of the stepped portion 1a limits the outer peripheral shape of the gas flow passage cross section, and the outer periphery of the flow passage cross section near the gas burner. Keep the shape constant.

This eliminates the risk that the secondary air flow will hit the stepped portion 1a of the burner case and disturb the flow.

Even if the secondary air flow collides with the upstream end of the burner mounting plate and disturbs the flow, the upstream end of the burner mounting plate is not located near the gas burner, which adversely affects the flame. Absent.

In this way, the secondary air flow is rectified in the vicinity of the gas burner and the flame shape of the gas burner is stabilized, so combustion noise is reduced.

〔Example〕

FIG. 1 is a sectional view showing an embodiment of the combustion apparatus of the present invention.

A stepped portion 1a is formed in the burner case 1, and a gas burner 3 is provided slightly upstream of the stepped portion (downward in the drawing).

A fan 6 is provided below the burner case 1 to forcibly supply combustion air.

The supplied combustion air passes through the pressure equalizing plate 10 and flows upward in the burner case 1.

The fuel gas is supplied from the gas nozzle 5, mixed with the primary air, ejected from the gas burner 3 into the secondary air stream, and burns to form a flame 9.

The high-temperature combustion product gas generated by the combustion heats water in the heat exchanger 7 and is discharged into the atmosphere through the exhaust pipe 8.

FIG. 2 shows a perspective view of the burner case 1 in the vicinity of the stepped portion 1a cut away, and FIG.
Shown in the figure. In FIG. 3, the horizontal direction of the paper surface is the longitudinal direction of the gas burner 3, and a large number of flames 9 are formed side by side in this direction.

The downstream side of the burner case stepped portion 1a is a small diameter portion 1b having a narrow cross-sectional shape, and the upstream side is a large diameter portion 1c having a large cross-sectional shape.

The burner mounting plate 2'of this example is aligned with the small diameter portion 1b of the burner case (specifically, the small diameter portion is aligned with an imaginary surface extending to the upstream side) and fixed to the large diameter portion 1c.

Since the upper end (downstream end) of the burner mounting plate 2'of this example is separated from the stepped portion 1a, the guide plate 4 is used to supplement this.
Is provided. The guide plates 4 are arranged along the virtual surface (extension surface of the small diameter portion 1b) and fixed to the large diameter portion 1c.

When implementing the present invention, the guide plate 4 may not be provided if the burner mounting plate 2'is configured to contact the stepped portion 1a.

FIG. 3 is a diagram corresponding to FIG. 6 in the conventional example. In FIG. 6, the outer circumference of the flow path of the gas that flows upward in the burner case 1 is sharply narrowed at the stepped portion 1a.

On the other hand, in FIG. 3 (this example), the outer periphery of the flow path of the upwardly flowing gas sharply narrows at the lower end of the burner mounting plate 2 ′ and becomes constant in the vicinity of the gas burner 3. .

For this reason, a part of the secondary air that has flown upward collides with the upstream end (lower end in the figure) of the burner mounting plate 2'and changes its direction as indicated by arrow d, but this part is separated from the gas burner 3. Therefore, it does not affect the flame 9.

Then, in the vicinity of the gas burner 3, the secondary air flow flows in a rectified state in parallel with the jet direction of the combustion gas as indicated by arrows c, c ′, c ″. Therefore, the combustion state of the flame 9 is stabilized. ,
Combustion noise is reduced.

When the combustion noise of the above-described conventional combustor (Figs. 5 and 6) was actually measured, it was 53 decibels (A scale), in contrast to this example under the same conditions (Figs. 1 to 3). The combustion noise shown in the figure) was 48 decibels (A scale), and a remarkable improvement effect was confirmed. The frequency analysis result is shown in FIG.

Especially, a remarkable reduction is recognized in the frequency band of 100 Hz to 300 Hz.

[Effect of device]

As described above, the burner case having the stepped portion in which the cross-sectional shape of the gas flow channel sharply narrows toward the downstream side, the gas burner installed on the upstream side of the stepped portion, and the burner case including the gas burner are provided. The present invention is applied to a combustion device including a burner mounting plate that is fixed to the burner case and a fan that supplies combustion air into the burner case, and the burner mounting plate is provided on the downstream side of the burner case stepped portion. Aligned and arranged,
If the outer peripheral shape of the cross section of the gas flow path in the vicinity of the gas burner is made uniform, turbulence of the secondary air flow can be prevented with a simple structure, flames can be stabilized, and combustion noise can be reduced.

[Brief description of drawings]

1 to 3 show one embodiment of the combustion apparatus of the present invention, FIG. 1 is a schematic cross-sectional view, and FIG. 2 is a perspective view of the vicinity of a gas burner cut away. FIG. 4 is a cross-sectional view of the vicinity of a gas burner. FIG. 4 is a chart showing the combustion noise by frequency analysis in order to explain the effect of the above embodiment. FIG. 5 is a perspective view in which the vicinity of the gas burner in the combustor of the conventional example is cut away and drawn, and FIG. 6 is a cross-sectional view near the gas burner of the conventional example. 1 ... Burner case, 1a ... Step part of burner case,
2, 2 '... Burner mounting plate, 3 ... Gas burner, 4 ...
Guide plate, 5 ... gas nozzle, 6 ... fan, 7 ... heat exchanger, 8 ... exhaust stack, 9 ... flame.

Claims (1)

[Scope of utility model registration request] 1. A burner case having a disconnecting portion in which the cross-sectional shape of a gas flow channel narrows sharply toward the downstream side, a gas burner installed upstream of the stepped portion, and a gas burner with respect to the burner case. In a fuel device comprising a burner mounting plate for fixing and a fan for supplying combustion air into the burner case, the gas burner has a large number of flame holes arranged in a longitudinal direction thereof, The burner mounting plate is fixed to the inner surface of the burner case so as to face the longitudinal direction of the gas burner, and the burner mounting plate has a cross-sectional shape aligned downstream of the stepped portion of the burner case. A combustion device which is arranged so that the outer peripheral shape of the cross section of the gas flow path does not sharply narrow toward the downstream side in the vicinity of the gas burner.