JPH0219366B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas burner in which a combustion plate is provided with a large number of gas ejection holes of different diameters, one large and one small.

[Conventional technology]

A gas burner that forcibly supplies a premixed mixture of fuel gas and combustion air and burns it under high load in a combustion chamber is very likely to generate resonance noise. This resonance occurs because the combustion flame vibrates at a specific frequency due to a pressure change when the mixture of fuel gas and combustion air is injected into the combustion chamber and a volume change due to combustion. That is, one resonance system is constituted by a fuel gas supply system, combustibility (including the combustion method), and a gas burner including a combustion exhaust stack. In particular, the source of the vibration is thought to be in the combustion section, that is, the combustion plate.

Therefore, as a technology to suppress the generation of resonance sound,
There is a gas burner in which a large number of gas ejection holes with different hole diameters are arranged on a combustion plate to avoid creating unique excitation conditions for each ejection hole (Special Publication No. 57).
-41648).

[Problem to be solved by the invention]

However, the air-fuel mixture flowing into the gas nozzle always has turbulence. Therefore, if a large-diameter gas nozzle hole and a small-diameter gas nozzle hole are drilled with the same diameter in the combustion plate, the large-diameter gas nozzle hole is extremely vulnerable to turbulence in the air-fuel mixture. Since the combustion flame always vibrates due to fluctuations in the flow rate of the air-fuel mixture in the gas supply system, resonance noise is particularly likely to occur during times when combustion is unstable, such as during ignition.

An object of the present invention is to provide a gas burner that can suppress vibrations of a combustion flame at a specific frequency, can also suppress the generation of resonance noise during times when combustion is unstable, such as during ignition, and can perform stable combustion.

[Means to solve the problem]

In order to achieve the above object, the present invention penetrates the front and back sides of a ceramic combustion plate to form a large number of small-diameter and large-diameter gas injection holes, and the large-diameter gas injection holes are inserted into the plate from the back side. A structure is adopted in which the thickness is made equal in diameter up to a predetermined position, and a large equal diameter part or a tapered part in which the pore diameter increases is formed between the predetermined position and the surface of the combustion plate.

[Action and effect of the invention]

With the above configuration, the gas burner of the present invention has the following functions and effects.

(1) A large number of small-diameter and large-diameter gas ejection holes are drilled through the front and back of the ceramic combustion plate. For this reason, by utilizing the unique excitation conditions of each gas nozzle and preventing them from interfering with each other to create a unified excitation condition, when the mixture of combustion gas and combustion air is ejected into the combustion chamber, Vibration of the combustion flame at a specific frequency due to pressure changes and volume changes due to combustion is suppressed.

(2) The large-diameter gas ejection holes have the same diameter from the back side to a predetermined position in the plate thickness, and from this predetermined position to the surface of the combustion plate, the large diameter part or the hole diameter increases. It forms a part. For this reason, the jetting speed of the air-fuel mixture is suddenly or gradually decelerated in the large-diameter portion or the tapered portion, which reliably prevents combustion flame lift, and prevents fluctuations and turbulence in the flow rate of the air-fuel mixture, as well as when jetting out. It has properties that are resistant to changes in pressure and volume due to combustion, and can suppress the generation of resonance noise during times when combustion is unstable, such as during ignition.

(3) Gas nozzles that are not large in diameter have the same diameter and are thin, so
Shows very good combustion (no lift or red-hot burning plates).

〔Example〕

The present invention will be explained based on embodiments shown in the drawings.

1 (forced air instantaneous gas water heater) to FIG. 3 show a first embodiment of the gas burner of the present invention.

The instantaneous gas water heater 1 houses a rectangular ceramic combustion plate 11, a blower 14, and a heat exchanger 15a inside, and forms a combustion case 16 whose interior is a combustion chamber 15 and an outside air inlet 17a. The main body case 17, a gas supply pipe 18, and an exhaust pipe 19 are provided.

As shown in FIGS. 2 and 3, the combustion plate 11 has a thickness of 13.2 mm in this embodiment, and has a large diameter gas injection hole 12 and a small diameter gas injection hole 13 with different hole diameters on the surface 11a. A large number of holes are formed alternately and regularly through the back surface 11b.

The gas ejection holes 12 are located on the surface 1 of the combustion plate 11.
A spout 12a is formed in 1a, and a small diameter part (l1=8 mm in this example) 12b, which is an equal diameter part, and a large diameter part (l1 in this example) that is coaxial with the small diameter part 12b.
2=5.2mm) has 12d.

The small diameter portion 12b is formed so that the hole diameter between 11 and 11 from the back surface 11b to the front surface 11a is larger than the gas ejection hole 13 and has the same diameter (in this embodiment, φ1: 1.90 mm).

The large diameter portion 12d forms a step 12c at the connecting portion with the small diameter portion 12b, and the step 12c is connected to the small diameter portion 12b.
The diameter of the hole from 2c to the spout 12a is the same, and the diameter is larger than that of the small diameter part 12b (in this embodiment, φ2;
2.40mm).

The gas ejection holes 13 are located on the surface 1 of the combustion plate 11.
A jet nozzle 13a is formed in 1a, and the hole diameter from the back surface 11b to the front surface 11a is smaller than that of the gas jet hole 12 and the same diameter (in this embodiment, φ3: 1.32 mm).

The operation of this embodiment will be explained.

A mixture in which fuel gas and combustion air are premixed is forcibly supplied into a combustion case 16 of an instantaneous gas water heater 1.

Here, the air-fuel mixture that flows into the gas injection holes 12 and 13 is always turbulent due to the pressure change when it is ejected and the volume change due to combustion. It is extremely sensitive to air turbulence, and resonates especially when combustion is unstable, such as during ignition.

In order to prevent the generation of this resonance sound, in the gas ejection hole 12 of the present invention, the flow velocity of the air-fuel mixture is reduced by the large diameter portion 12d. In addition, in order to obtain a sufficient deceleration effect, the length l2 of the large diameter portion 12d and the length l2 of the small diameter portion 12b are
The value of the ratio to the diameter φ1 (l2/φ1=5mm/1.9mm)
It is desirable that the value is 2 or more. Also, φ1 and φ3
and φ1=1.7mm~2.5mm and φ3=1.1mm~ respectively.
1.9mm (always φ1>φ3) is desirable.

For this reason, since the air-fuel mixture has different opening areas of the ejection ports 12a and 13a of the gas ejection holes 12 and 13, the ejection speed and pressure loss of the air-fuel mixture are also different.
Therefore, each combustion flame oscillates at various frequencies. Therefore, by making use of the unique excitation conditions of the gas nozzles 12 and 13 and preventing them from interfering with each other to create a unified excitation state, when the mixture of fuel gas and combustion air is ejected, Vibration of the combustion flame at a specific frequency due to pressure changes and volume changes due to combustion is suppressed.

In addition, since the gas jet hole 12 suddenly expands at the step 12c between the small diameter part 12b and the large diameter part 12d, the jetting speed of the air-fuel mixture is rapidly reduced in the large diameter part 12d, and at the jet port 12a. It can reliably prevent lift of the combustion flame, and is resistant to fluctuations and turbulence in the flow rate of the air-fuel mixture, as well as changes in pressure when ejected and changes in volume due to combustion, making combustion unstable during ignition. It is possible to suppress the generation of resonance sounds at certain times.

Since the gas ejection holes 13 are small-diameter gas ejection holes, they are effective in imparting very good ignition performance to the gas burner and holding the combustion flame on the surface 11a of the combustion plate 11.

That is, the gas burner of the present invention can always perform stable and good combustion from ignition to extinguishment by the two types of gas ejection holes 12 and 13 having different diameters.

FIG. 4 shows a second embodiment of the invention.

The combustion plate 31 of the gas burner of this embodiment is as follows:
A large number of gas ejection holes 32 and 33 of different diameters are regularly and alternately bored.

The gas ejection hole 32 has a small diameter portion 32b, a small diameter portion 32
It has a tapered portion 32c formed with the hole diameter tapered from b toward the spout 32a.

In this example, φ4; 1.90mm, φ5; 2.40mm, l3
= 8.0mm, l4 = 5.2mm.

That is, in the gas jet hole 32, the small diameter portion 32b
Since there is no step between the air-fuel mixture and the tapered portion 32c, and the air-fuel mixture is smoothly continuous, the jetting speed of the air-fuel mixture is gradually reduced.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view showing an instantaneous gas water heater to which the first embodiment of the gas burner of the present invention is applied;
The figure is a front view of the combustion plate according to the first embodiment of the gas burner of the present invention, and FIG. 3 is a sectional view of the combustion plate according to the first embodiment of the gas burner of the present invention.
FIG. 4 is a sectional view of a combustion plate according to a second embodiment of the gas burner of the present invention. In the figure 1... Instantaneous gas water heater, 11, 31... Combustion plate, 11a... Front surface, 11b... Back surface, 12,
32...Gas outlet (large diameter gas outlet), 12d
...Large diameter part (equal diameter large part), 13, 33...Gas ejection hole (small diameter gas ejection hole), 32c...Tapered part (tapered part) l1, l3...From the back side to a predetermined position of the plate thickness distance.

Claims (1)

[Scope of Claims] 1. A large number of small-diameter and large-diameter gas injection holes are formed through the front and back sides of a ceramic combustion plate, and the large-diameter gas injection holes extend from the back side to a predetermined position in the thickness of the plate. A gas burner characterized in that the holes are of equal diameter, and a large portion of equal diameter or a tapered portion of increasing hole diameter is formed between the predetermined position and the surface of the combustion plate.