JPS6298110A - High load combustion method and device thereof - Google Patents

Abstract

PURPOSE:To enable high load combustion, by constituting arrangement of burner ports, a flame stabilizing mechanism, and a vibration combustion preventing mechanism. CONSTITUTION:A flame-holding wall 3 is formed by a heat resistant material around a burner port surface 1 formed with a plane, and the flame stabilizing wall is formed in a discontinuous state in spots. A number of burner ports 2 are formed in a checkered state in the burner port surface, a pressure uniformizing space is formed at the back of the burner port surface, and a blower 8, feeding premixing gas, is situated in the pressure uniforming space. In which case, the size of the burner port 2 of a burner is set to 1.2-2mm to increase a combustion amount per a unit area of a burner, and a distance between the centres of the adjoining burner ports is set to 3-5mm, so that lift is difficult to occur. A flame-holding wall 3 having a height of 8-15mm is formed around the periphery of a burner surface, and if a distance between the outer periphery, positioned nearmost the flame-holding wall, of the burner port and the flame stabilizing wall is set to 2mm or less, lift of flame can be effectively prevented from occurring. Further, positioning of a flow-straightening plate 5, having an opening 4 with a total area equal to that of the burner port, in a position situated 3-10mm away from a burner port surface bottom part on the the upper stream side of the burner port, enables prevention of the occurrence of vibration combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is used in water heaters and the like. The present invention relates to a so-called high-load combustion method and combustion apparatus for burning a large amount of gas with a short flame using a small burner area.

[Prior art and its problems] In conventional water heaters, etc., the so-called Bunzen burner is mainly used, but since it requires secondary air to complete combustion, it has a relatively large combustion chamber. It cost.

On the other hand, in order to downsize water heaters, it is necessary to shorten the flame, so from this point of view, so-called premix burners, which premix gas and air and burn it, are sometimes used. Ceramics have also been used as burner materials in this case. According to premix combustion, combustion can be completed without secondary air, so the combustion chamber can be made smaller. However, in order to make the combustion chamber even smaller, the amount of combustion per unit area of the burner must be increased, so-called high-load combustion. In this case, flame instability and oscillatory combustion are likely to occur, so special consideration is required. Conventional ceramic premix burners have a relatively small inner diameter of 1
It was equipped with a large number of flame holes on the order of millimeters in diameter, and used a combustion method that caused the surface to become red-hot, similar to those used for radiant stoves. However, when the combustion rate is increased in such a burner, the flame lifts because there is no special flame-holding mechanism, and the red heat of the burner remains even after combustion is stopped when used in a water heater. The residual heat then heats the water remaining in the boiler, causing so-called after-boiling, where superheated water comes out for the next use, which is undesirable, and the burner material is made of expensive materials that can withstand high temperatures. It becomes necessary.

On the other hand, in the conventional ceramic premix burner, the flame formed in each flame hole is not independent, and the flame is formed across a plurality of flame holes, so the flame length is long. Furthermore, it is known that burners with short flames and a large amount of combustion per unit area of the burner tend to cause oscillatory combustion.
Many had no means to prevent this.

[Objective of the present invention] The purpose of the present invention is to solve the above-mentioned problems and provide a combustion method and a combustion device thereof that are capable of high-load combustion without causing burner red heat or oscillating combustion. .

[Configuration of the present invention] The configuration of the present invention is as follows.

1. High-load combustion by supplying premixed gas with a blower to a burner that has a flame holding wall around the flame hole surface and a large number of flame holes on the flame hole surface surrounded by this flame holding wall. Combustion method.

2. A flame-holding wall is formed from a heat-resistant material around the flat flame hole surface, and this flame-holding wall is discontinuous at several places, and the flame hole surface is provided with a large number of flame holes in a checkerboard pattern. and a pressure regulating space is formed on the back side of the flame hole surface,
This high-load combustion device is equipped with a blower that supplies premixed gas to this pressure regulating space.

The present inventors have discovered that certain conditions as described below are necessary when completing the above-mentioned present invention. The main points are as follows.

(1) If the diameter of the flame hole of the burner exceeds approximately 2 mm, flashback may occur in gases with a high combustion rate.
If it is smaller than 1 or 2 mm, the total area of the flame holes becomes too small due to restrictions regarding the distance between the flame holes as will be described later, and the amount of combustion per unit area of the burner cannot be increased.

(2) The distance between the centers of the four flame holes is 3s or more5IIIl
If it is less than 3a+m, the burner surface tends to become red hot, and if it is less than 2m+s, the flame in each flame hole may connect to form a sheet-like flame, and the flame holding performance is extremely poor. decreases to Further, if the distance is 5 mm or more, the mutual stabilizing effect of adjacent flames is reduced, and lift is likely to occur.

(3) Flame lift can be prevented by providing a flame-holding wall with a height of 8 mm or more and 15 em or less around the burner surface. If the height is less than 8 mm, the flame holding ability will be low;
If it is 5 mm or more, the flame-holding wall will become red hot.

(4) The position and arrangement of the flame hole provided closest to the flame-holding wall is extremely important for preventing lift. The distance between the outer periphery of the flame hole closest to the flame-holding wall and the flame-holding wall must be 2n or less, and if it is 2+++ m or more, the flame above the flame hole is likely to lift, and as a result, the flame is extinguished over the entire flame hole surface. I end up.

Further, by arranging the flame holes in a grid pattern and arranging all the flame hole rows adjacent to the flame holding wall at equal distances from the flame holding wall, lift can be effectively prevented.

(5) In order to prevent oscillatory combustion, it is necessary to place the burner at a distance of 3 mm or more and 10 m from the bottom of the burner hole, on the upstream side of the burner hole surface.
It is effective to place a rectifier plate having an opening area comparable to the total area of the eight flame holes at a position below a+. The opening of the current plate may be a large number of flame holes of appropriate size, but if the distance from the bottom of the burner flame hole surface is 3 mm or less, the flames on the flame holes facing the openings on the current plate will be connected to each other. As a result, an independent flame cannot be formed in each flame hole, resulting in a long flame.

On the other hand, in the case of 10 m+s or more, the volume of the space between the baffle plate and the burner flame hole surface becomes large, and the vibration combustion suppressing effect decreases. The total area of the openings on the current plate may be approximately the same as the total area of the flame holes, and a plurality of openings may be installed.

(6) In order to suppress oscillatory combustion and flashback, it is effective to set the thickness of the burner flame hole surface to 8 m11 or more.

[Example] Fig. 1 is a perspective view of a high-load combustion burner used in the present invention, and Fig. 2 is a sectional view taken along the line A-A'. Flame holes 2 of 1.2 mm or more and 2 cm or less are provided in a grid pattern, and the distance between the centers of each flame hole 2 is 3 mm or more and 5 mm or less. The burner flame hole surface 1 is surrounded by a flame holding wall 3 with a height of 8 mm or more and 1 m or less, and the flame hole 2 closest to the flame holding wall 3
The distance between the outer periphery of the flame holding wall 3 and the flame holding wall 3 is set to be 2+a+s or less, and all the flame holes 2 are equidistant from the flame holding wall 3. Comparing this with a flame hole in which all the flame holes are arranged in a staggered manner, the flame hole indicated by 2' in Figure 3 is stable, but the flame hole indicated by 2 is, as a result, more stable than the flame hole 2'. The distance between the flame holes becomes large, making it unstable and reducing the flame holding ability. In other words, the flame formed in the flame hole 2' closest to the flame holding wall 3 is stabilized by the vortex generated between the adjacent flame holes 2' and between the flame hole 2' and the flame holding wall 3. This is caused by a vortex, but if the distance between the flame holes 2' is too large, the vortex generated between the flames in each flame hole 2' will also be excessive, conversely making the base of the flame unstable.

Therefore, when forming independent flames in each flame hole as in the present invention, the distance between each flame hole is 31111 or more and 5a.
+m or less, which is larger than conventional ceramic burners,
In order to prevent the distance between the flame holes near the flame holding wall 3 from becoming too large, it is necessary to arrange them in a grid pattern. A new flame holding hole 2 is added approximately at the center of the flame holding hole 2 with a distance of 2 m between the flame holding wall 3 and the outer periphery of the flame holding hole 2.
By providing it so that it is below m, flame holding ability can be improved.

On the other hand, in the rectifying space 2e formed on the back side of the burner hole surface 2, on the upstream side at a distance of 3a+m or more and 10 mm or less from the burner flame hole surface 2, there is one or more rectifying plates 5 having openings 4. The total area of the opening 4 is approximately the same as the total area of the flame hole 2. The diameter of the opening 4 may be larger than the diameter of the flame hole 2, but even in that case, an independent flame can be formed in each flame hole 2 by separating it from the bottom of the flame hole surface l by 3 mm or more. . FIG. 4 shows the flame shape when the distance between the rectifying plate 5 and the burner flame hole surface 1 is IIIm, and the flames on the flame holes 2 facing the openings 4 of the rectifying plate 5 are connected to each other. This becomes one flame 6, which is longer than the flames 7 that are formed independently. Against this.

When the distance is set to 3■ or more. As shown in FIG. 5, independent flames 7 are formed in each flame hole in the flame holes 2 facing the openings 4 of the current plate 5, and short flame combustion is obtained throughout.

In addition, when the flame hole surface 2 is square, the flame-holding wall 3 is made of independent ceramic on each side, and is designed to butt against each other at each joint to create some play. The purpose of this is to absorb thermal stress due to heat load during high-load combustion, and the burner surface 2
This can prevent damage to the flame-holding wall 3.

In addition, 8 in the figure is a blower for pumping the premixed gas into the rectification space 2a, and as an example, the premixed gas at the stoichiometric air ratio is 600t/ak when the total flame hole area is 18c♂.
It is feeding in.

A metal fitting 9 fixes the flame-holding wall 3, and a heat-resistant gasket 10 is inserted between the flame-holding wall 3, the metal fitting 9, and the burner body 1a for gas sealing.

[Effects of the present invention] The present invention configures the arrangement of the flame holes, the flame holding mechanism, and the vibration combustion prevention mechanism as described above to achieve high-load combustion, so that the following effects can be obtained. can.

(1) Flame holes are formed in a grid pattern to provide thermal interference to the flame, and a flame-holding wall is provided around the area, so even if the amount of combustion per unit area of the burner is increased, lift is unlikely to occur, resulting in stable combustion. is obtained. Also, if the flame holes in the center are in a staggered arrangement,
Stable combustion is obtained by adding a flame holding flame hole near the center of each flame hole with excessive spacing close to the flame holding wall.

(2) An independent flame is generated in each flame hole, resulting in a short flame.

(3) Since the flame hole surface and the flame-holding wall do not become red-hot, ceramic materials with poor heat resistance can be used, and no after-boiling occurs when applied to hot water baths.

(4) Vibration combustion is less likely to occur by providing a rectifying plate and by setting the thickness of the flame hole surface to a certain level or more.

(5) By making the flame stabilizing wall discontinuous, thermal stress can be absorbed and the durability of the burner can be improved.

(6) By forming a rectifying space on the back side of the flame hole surface,
A uniform independent flame can be formed in each flame hole.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a high-load combustion device (gas burner) according to the present invention, Fig. 2 is a sectional view taken along the line A-, Fig. 3 is a comparative plan view showing a part of the flame hole surface, Fig. 4, FIG. 5 is a partial sectional view of the flame hole surface showing the combustion state. ■・・・flame hole surface, 2・・・flame hole,
3... Flame-holding wall, 4... Opening, 5
・・・・・・Rectifier plate, 6.7・・・・・・Flame,
8...Blower, 9...Metal fittings,
10...Heat-resistant packing. Figure 4 Figure 5

Claims (1)

[Claims] 1. Premixed gas is supplied by a blower to a burner in which a flame holding wall is provided around the flame hole surface and a large number of flame holes are provided on the flame hole surface surrounded by this flame holding wall. A high-load combustion method that burns 2. A flame-holding wall is formed from a heat-resistant material around the flat flame hole surface, and this flame-holding wall is discontinuous at several places, and the flame hole surface is provided with a large number of flame holes in a checkerboard pattern. and a pressure regulating space is formed on the back side of the flame hole surface,
This high-load combustion device is equipped with a blower that supplies premixed gas to this pressure regulating space. 3. The high-load combustion device according to claim 2, wherein the flame holes are arranged in a staggered manner.