JP2002039514A - Low-noise gas burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce burning noise of gas burners used for, such gas appliances as water heater, bath boiler and boiler for home use or office use. SOLUTION: A gas burner 10 is provided with burner ports 13A comprising a plurality of column form hollow structures, arranged vertically on the upper surface of a mixing chamber 16A and the form of the horizontal cross section of the burner port 13A is such that the length of circumference of the burner port at the horizontal cross section is 1.15 Lo or less, where the area of the burner port at the horizontal cross section is S and the length of the circumference of a circle having the area of the S is Lo.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas burner having a plurality of column-shaped cavities running vertically on the upper surface of a mixing chamber as a flame outlet.
The present invention relates to a gas burner used for gas appliances such as bath kettles and boilers.

[0002]

2. Description of the Related Art Premixed combustion is an effective combustion method for achieving low NOx in gas burners used for gas appliances such as domestic and commercial water heaters and bath kettles. However, premixed combustion has a narrower flame stability range than Bunsen combustion, and various measures have been taken for gas burners using premixed combustion in practical combustors, resulting in a complicated combustor structure. Has become. This tendency is particularly large in the case of lean premixed combustion.

It is also known that combustion noise has a correlation with turbulence energy ("Effect of flow velocity fluctuation on combustion noise", Kagiya, Hase, 33rd Combustion Symposium Preprints, p. 183). In the premixed lean combustion, by mixing a large amount of air with the fuel gas in advance, the flow rate of the jet from the burner flame increases, which tends to disturb the premixed airflow of the fuel gas and air. In the mixed lean combustion, the combustion noise of the burner flame tends to increase.

As a gas burner which solves these inconveniences, there has been proposed a gas burner having a plurality of vertically extending column-shaped cavities as a flame outlet on the upper surface of a mixing chamber (for example, JP-A-6-109218). Gazette). In this type of gas burner, flame blow-off is less likely to occur, combustion is stabilized, and the flow of premixed gas is rectified in a column-shaped space running vertically, so it is compared with a gas burner with a flat opening as a flame opening Thus, the combustion noise is reduced to some extent. As another embodiment, a low-noise type burner in which a wall surface (flame holding plate) is provided near a flame to suppress turbulence of the flame has been proposed (see Japanese Patent Application Laid-Open No. 1-277105). In this burner, it can also be expected that the combustion noise is suppressed by the flame holding plate.

[0005]

A burner having a flame opening in which the premixed gas passes through the vertically extending columnar space is rectified in the columnar space as described above. Thereby, combustion noise can be suppressed to some extent. However, it is necessary to increase the length of the column-shaped space in order to perform sufficient rectification, and if it is increased, the pressure loss at the burner increases. For this reason, it is necessary to increase the size of the fan and increase the number of rotations of the fan, and as a result, the noise of the entire device increases due to the increase in the fan noise. Therefore, taking the measures against combustion noise in the above-described embodiment is not always an effective means. Further, an increase in the length of the columnar void means an increase in the size of the burner, which is not preferable from this viewpoint. The aspect in which the wall surface (flame holding plate) is provided near the flame has the drawback that the burner structure becomes complicated and the cost increases because the number of combustor parts increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-noise gas burner which can be used without increasing equipment noise by reducing pressure loss while greatly reducing combustion noise. Another object of the present invention is to provide a low-noise gas burner which is small in size and simple in structure and can be manufactured at low cost.

[0007]

The present inventors have conducted a number of experiments to solve the above-mentioned problems, and have found that, in the case of a gas burner having the same horizontal cross-sectional area, the area around the burner flame outlet is reduced. There is a correlation between the length and the combustion noise, and the shorter the circumference, the lower the combustion noise. The circle has the shortest perimeter when the area is the same, and a large combustion noise reduction effect was obtained when the horizontal cross-sectional shape of the flame outlet was a circle, but the perimeter ratio to the circle was within a certain range. As a result, the present inventors have also experienced that even if the horizontal cross-sectional shape is other than a circle, a significant combustion noise reduction effect can be obtained as compared with the conventional one. In addition, it has been found that the required noise reduction can be achieved even if the length of the column-shaped cavity running in the vertical direction in the conventional low-noise burner is significantly reduced.

The present invention is based on the knowledge obtained from the above experiments, and the low-noise gas burner according to the present invention basically has a plurality of column-shaped cavities running vertically in the upper surface of the mixing chamber. In a gas burner having a port, when the area of a horizontal section of each flame port is S and the peripheral length of a circle having the area S is Lo, the peripheral length of the flame port on the horizontal plane is 1.15 Lo. It is characterized by having the following shape.

Provided that the above conditions are satisfied, the shape of each flame outlet in a horizontal section is arbitrary, and may be a circle, a regular polygon,
Examples include a rectangle, an ellipse, and an oval. In the case of a circle, the greatest combustion noise reduction effect is obtained. The manufacturing form of the gas burner as a whole is arbitrary, but a plurality of recesses are formed by bending a plurality of recesses in the vertical direction like a gas burner used for gas appliances such as a conventional household or business water heater or bath kettle. The form of the burner formed by arranging a suitable number of the metal plates in parallel is a preferable form because the manufacture is easy and the cost is low.

The low-noise gas burner according to the present invention achieves low noise in both Bunsen combustion and premix combustion. Premixed combustion, especially lean premixed combustion, is likely to be accompanied by loud combustion noise, and premixed lean combustion that achieves low NOx in gas appliances such as domestic and commercial water heaters and bathtubs should be adopted. Considering that this is an important issue, the present invention is a particularly preferable embodiment in a gas burner for premixed combustion, particularly lean premixed combustion.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the results of experiments performed by the present inventors. First, the correlation between the perimeter (mm) and the turbulence energy W was determined while keeping the flame opening area constant. As shown in Table 1,
When the vertical and horizontal dimensions of the rectangular flame outlet were changed while keeping the flame mouth area constant (72 mm ² ), as shown in FIG. 1, as the perimeter became shorter, the energy W of the turbulence on the flame outlet decreased. The energy W of turbulence is minimized when the perimeter of the burner flame is the shortest (when the aspect ratio is minimum)
Met. Further, with the same flame area, the turbulent energy W was minimum when the flame was circular.

[0012]

[Table 1]

The combustion noise was measured by using a burner having a plurality of flame openings, and using a burner having the same total area of the flame openings and changing the vertical and horizontal dimensions of the rectangular flame openings. As described above, a result was obtained in which the combustion noise became smaller as the perimeter at one flame outlet was shorter. Further, FIG. 3 shows the horizontal axis replaced by the ratio of the perimeter L of the flame at each measurement burner to the perimeter Lo when the flame is assumed to be a circle. As can be seen from FIGS. 2 and 3, when the flame opening area is determined in advance, to reduce the combustion noise in the gas burner, as predicted from the relationship between the turbulent energy and the combustion noise, it is preferable to reduce the combustion nozzle shape. It is most desirable that the shape of the flame port in the horizontal cross section is circular because its perimeter affects the combustion noise. For example, even if the flame port cross section is non-circular such as a rectangle, the L / Lo value If the value is smaller than a certain value, the intended purpose can be sufficiently achieved.

The arrows a, b, and c in FIG. 3 indicate the L / Lo values of the burner flame outlet in a burner of a currently marketed water heater, and are approximately 1.38 (arrow a). It is about 1.19 (arrow b) and about 1.176 (arrow c). The combustion noise of the burner itself in these water heaters is unknown, but the equipment noise (measured by JIS) is 4
It is about 8 dB. Therefore, in the present invention, the shape of the horizontal cross section of each flame outlet is not limited to a circle, and the peripheral length is 1.15 Lo.
It can be seen that the intended purpose is sufficiently achieved even if the shape (regular polygon, rectangle, ellipse, oval, etc.) is less than (Lo: circumference length in the case of a circle) or less.

FIG. 5 and FIG. 6 show examples in which the knowledge obtained by the above experiment is applied to an actual gas burner.
The gas burner 10 is a gas burner of a type formed by arranging a suitable number of thin metal plates 11 and 12 press-formed into a required shape in parallel, and can be manufactured at low cost by pressing the thin metal plates. It is usually used for gas appliances such as domestic and commercial water heaters and bath kettles. The metal thin plate 11 and the metal thin plate 12 are paired, and a concave portion having a predetermined shape is formed in a mirror-symmetrical manner.
As a result, a single burner plate having a gas-air inflow path, a mixing chamber, a flame port, and the like is formed, and a plurality of the burner plates (five in the illustrated example) are juxtaposed. A gas burner 10 is formed.

In the example of FIG. 5, the metal sheets 11 and 12
In the upper part, there are recesses 13, 14 having a substantially semicircular shape in a horizontal cross section and having a required length in the vertical direction, and a recess for a mixing chamber which integrally communicates the lower ends of the recesses 13, 14. 1
6 and 17 (17 is not shown), and recesses 18 and 19 for a gas air inflow passage are formed,
12 are integrated, a gas-air inflow passage recess 18A having an opening 18B on the side, a gas-air mixing chamber 16A connected to the gas-air inflow passage recess 18A, And a plurality of flame holes 13A as column-shaped cavities running in the vertical direction, the horizontal cross-sections of which are formed by the recesses 13 and 14 having a length of a circle. Five gas burners 10 are arranged side by side.

The gas burner 10 shown in FIG. 6 uses a pair of thin metal plates 11 and 12 having recesses 15 and 16 having a substantially U-shaped horizontal cross-sectional shape formed in the upper part. Except that it is formed, it is the same as that shown in FIG. In this gas burner, the recesses 15 and 16 having a required length in the vertical direction and having a substantially U-shaped horizontal cross section form a plurality of column-shaped cavities running in the vertical direction having a substantially square horizontal cross section. 1 flame outlet
5A is provided on the upper surface of the mixing chamber.

The gas burner 10 shown in FIGS. 5 and 6 has a plurality of column-shaped cavities running vertically in the upper surface of the mixing chamber 16A as flame ports 13A and 15A.
A and 15A have a circular cross section (FIG. 5) or a square (FIG. 6) in a horizontal section. That is, the flame outlet 13A,
Assuming that the cross-sectional area of 15A is constant S, the circumference is the shortest circle (FIG. 5) or the square having the aspect ratio of 1 (FIG. 6). Thus, the horizontal cross-sectional area of the flame outlet is the same (S),
Combustion noise generated at the time of combustion is surely reduced as compared with a gas burner whose horizontal cross-sectional shape is an ellipse, an ellipse, or a rectangle having an aspect ratio of 1 or more.

Further, since the flame opening is a column-shaped space running in the vertical direction, the mixture is rectified by the passage of the premixed gas, thereby reducing the combustion noise. As described above, the required reduction is achieved by the horizontal cross-sectional shape of the flame outlet, so that even if the flame outlet has a length shorter than the length of the column-shaped space running in the vertical direction in the conventional gas burner, the combustion noise of the gas burner as a whole will be reduced. The required reduction rate can be achieved, and as a result, it is possible to manufacture the gas burner 10 with small pressure loss and reduced size.

The above-described reduction of the combustion noise similarly occurs in both Bunsen combustion and lean premix combustion. However, a large amount of combustion noise is usually generated in the lean premixed combustion. Therefore, in the gas burner 10 shown in FIGS. 5 and 6, the fuel gas is mixed so that a premixed gas of fuel gas and air is formed in the mixing chamber 16A. By supplying and burning air, a high practical effect is brought about.

As shown in FIG. 3, the L / L of the burner flame outlet of a burner in a currently marketed water heater is shown.
The o-values are about 1.38 (arrow a), about 1.19 (arrow b), and about 1.176 (arrow c), and the appliance noise in these water heaters is about 48 dB. Therefore, the gas burner used in such a water heater has a circumference of 1.1.
By substituting the gas burner according to the present invention having a flame opening shape of not more than about 5Lo (Lo: circumference length in a circle), it can be expected that combustion noise and appliance noise can be suppressed to lower levels.

FIG. 4 shows an example of the horizontal cross-sectional shape of the flame outlet according to the present invention. 4a and 4b show the above-mentioned square and circle shapes. Further, it can be easily predicted that the intended purpose can be achieved even with a regular polygon such as a regular hexagon or regular octagon as shown in FIGS. It is also effective to add an R to the corner as shown in FIG. 4E. Further, as shown in FIG. 4f, a vertical partition plate 20 for dividing the columnar cavity into a plurality of sections may be provided in the columnar cavity forming the flame outlet, and even if the pressure loss is somewhat increased, A high combustion noise reduction rate is achieved. Further, when the horizontal cross section is a rectangular flame port, the aspect ratio 1 provides the highest combustion noise reduction rate. However, even in the case of a rectangular flame port having an aspect ratio of 2 or less, preferably 1.5 or less, the conventional method can be used. Thus, a gas burner with reduced combustion noise can be obtained more reliably.

[0023]

According to the present invention, the pressure loss is small while the combustion noise is greatly reduced, and the structure is small and the structure is simple.
A low-noise gas burner that can be manufactured at low cost is obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing a correlation between a burner flame circumference and turbulent energy.

FIG. 2 is a graph showing a correlation between a burner flame circumference and a combustion noise level.

FIG. 3 is a graph showing a correlation between a ratio of a circumference of a burner flame opening to a circumference of a circle and a combustion noise level.

FIG. 4 is a conceptual diagram showing some embodiments of a burner flame outlet.

FIG. 5 is a perspective view showing one embodiment of a low-noise gas burner according to the present invention.

FIG. 6 is a perspective view showing another embodiment of the low-noise gas burner according to the present invention.

[Explanation of symbols]

Reference numeral 10: gas burner, 11, 12: thin metal plate, 13, 14
... a plurality of vertical recesses formed in a thin metal plate, 13A ...
Flame mouth as a column-shaped space running in the vertical direction (horizontal cross section is circular), 16A: mixing chamber, 18A: gas air flow

Continuation of the front page (72) Inventor Yasushi Yasui F-term (reference) 3-20, 1-5-20, Kaigan, Minato-ku, Tokyo 3G017 AA07 AA08 AB02 AB07 AB09 AB10 AC01 AD11 3K065 TA07 TA15 TB02 TC01 TC02 TD05

Claims (7)

[Claims] 1. A gas burner having a plurality of vertically extending column-shaped cavities on the upper surface of a mixing chamber as a flame outlet, wherein an area in a horizontal cross section of each flame opening is S, and a circle whose area is S is provided. A low-noise gas burner characterized in that, when the peripheral length of the gas outlet is Lo, the peripheral length of the flame outlet in a horizontal section is 1.15 Lo or less. 2. The low-noise gas burner according to claim 1, wherein a shape of each of the flame outlets in a horizontal section is a circle or a regular polygon. 3. The low-noise gas burner according to claim 2, wherein the shape of each flame outlet in a horizontal section is rectangular. 4. The low-noise gas burner according to claim 2, wherein a shape of each of the flame outlets in a horizontal section is an ellipse or an oval. 5. The gas burner is formed by arranging an appropriate number of metal plates having portions formed by bending and forming a plurality of recesses in a vertical direction, and the column-shaped vacancy as the flame port is adjacent to the metal plate. The low-noise gas burner according to any one of claims 1 to 4, wherein the recess is formed between the metal plates. 6. The low-noise gas burner according to claim 1, wherein the column-shaped cavity is provided with a vertical partition plate for dividing the column-shaped cavity into a plurality of sections. 7. The low-noise gas burner according to claim 1, wherein a pre-mixture of fuel gas and air is formed in the mixing chamber.