JPH0225614A - Surface combustion burner - Google Patents

Abstract

PURPOSE:To increase a turn-down ratio as well as a combustion load and to restrict combustion noise by a method wherein a flame port is arranged toward a direction along a flat combustion surface, a combustion secondary air supplying passage is formed at a rear part of a wall forming a combustion surface and discharging ports are arranged at both sides of mixture gas injecting passages from the flame port. CONSTITUTION:Mixture gas is ignited, a flame is formed at a flame port 3. Hot gas including an unburnt component flows along a combustion surface 2a, a combustion secondary air from an electric fan 8 is dispersed and mixed with hot gas from a discharging port 11 so as to ignite the unburnt component in the hot gas and a flame F is formed while being adhered to a combustion surface 2a. In case of a low input condition, the flame F is formed at a part near the flame port 3 of the combustion surface 2a and in turn in case of a high input, the flame F is formed over an entire combustion surface 2a and the combustion surface 2a may act as an apparent flame port, resulting in that a variation of a heating calorie per a flame port area is restricted low, a maximum heating calorie and a turn-down ratio are increased, and combustion noise can be restricted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface combustion burner having a flat combustion surface facing upward or downward so that it can be placed close to a heated object.

[Conventional technology]

Conventionally, as shown in FIG. 7, an upwardly or downwardly facing flat combustion surface (21a) is formed by a porous wall (21) such as a wire mesh or porous ceramic, and the porous wall (21)
An air-fuel mixed gas supply pipe (23) is connected to the back space (22) of the combustion surface (
21a) side, and surface combustion was performed using an all-primary air method.

[Problem to be solved by the invention]

However, when attempting to perform high-load combustion, the amount of mixed gas passing through the porous wall (21) is large due to the all-primary air method, and the jetting speed of the mixed gas towards the combustion surface (21a) is reduced. As the flame increases, the flame lifts, and the combustion load cannot actually be increased very much.

Also, when trying to reduce the input, the combustion surface (2
As the jetting speed of the mixed gas to the 1&) side becomes smaller,
Since it is an all-primary air system, flashback occurs and the input cannot actually be made very small, so the turndown ratio is relatively small.

Furthermore, since the change in the flame caused by adjusting the input is not very large, it is difficult to adjust the input, and it is easy to extinguish the fire unexpectedly, especially when the input is made extremely small.

Furthermore, since it is an all-primary air system, combustion noise increases, especially when the combustion load is increased.

In short, depending on the application, it is insufficient in terms of high-load combustion and turndown ratio, and there is also room for improvement in terms of operability and combustion noise suppression.

An object of the present invention is to provide a high-performance surface combustion burner that can significantly increase the combustion load and turndown ratio, easily perform input adjustment, and sufficiently suppress combustion noise. .

[Means to solve the problem]

The characteristic means of the present invention is to provide a flame port that spouts a mixed gas of gas fuel and primary air for combustion in a direction along a flat combustion surface upward or downward, and to supply secondary air for combustion from an electric fan. A secondary air supply path is formed at the back of the wall forming the combustion surface, and a discharge port of the secondary air supply path is connected to the combustion surface forming wall, and a mixed gas ejection path from the flame port is connected to the combustion surface forming wall. The reason is that they are arranged on both sides and are formed continuously or intermittently along the mixed gas ejection path, and their functions and effects are as follows.

[For production]

In other words, as shown in FIGS. 3 and 4, for example, when the mixed gas ejected from the flame port (3) is combusted in the direction along the flat combustion surface (2a), a flame is generated at the flame port (3). formed,
The high-temperature gas containing unburned components flows laterally along the combustion surface forming wall (2), and the secondary combustion air from the discharge ports (11) arranged on both sides of the mixed gas jetting path flows into the high-temperature gas. The unburned content in the high-temperature gas is diffused and mixed into the combustion surface (2a) of the wall (2).
) forms a flame (F) and burns.

When the input is low, the flame (F) is formed only in the area close to the flame outlet (3) as shown in Figure 3, and as the input increases, the tip of the flame (F) moves closer to the flame outlet (3). When the input is high, the flame (F
) is formed up to the outer periphery of the wall (2).

In short, although it is a surface combustion burner, it is configured to use a combustion method that is completely different from the conventional all-primary air method, in other words, it is configured to burn using primary combustion air and secondary combustion air. Item 2)
As will be explained in detail in section 1, it is possible to increase the combustion load and turndown ratio, as well as to easily adjust the input and suppress combustion noise.

(b) The amount of primary combustion air included in the mixed gas ejected from the flame nozzle is much smaller than in the all-primary air method (for example, about 175), so the amount of mixed gas ejected from the flame nozzle is sufficiently reduced. Moreover, even if the flame nozzle is made quite large, the mixed gas is ejected in the direction along the combustion surface and burns on the surface, so a good surface combustion condition can be maintained. By sufficiently slowing down the mixed gas injection speed, it is possible to maintain good surface combustion without flame lift, and it is possible to achieve a significant increase in combustion load.

(rl) The mixed gas ejected from the flame nozzle does not contain enough primary combustion air to completely burn the gas fuel, so by reducing the input, the mixed gas ejection speed from the flame nozzle is limited to just the flame nozzle. Even if the flame is reduced to the extent that a flame is formed, flashback does not occur, and stable combustion can be achieved with a sufficiently small input. In other words, that and the above (a)
The downdown ratio can be greatly increased by increasing the combustion load.

(c) When the input is changed, the flame formation range changes greatly in the direction along the combustion surface, so the input can be easily adjusted as desired while watching the flame.

(D) As the input increases, the area of the part of the combustion surface where flames are formed increases, and the amount of heat generated per unit area of the combustion surface can be kept small regardless of the input, so combustion noise can be sufficiently reduced. It can be suppressed.

〔Effect of the invention〕

As a result, we have provided a surface combustion burner with extremely high maximum calorific value, which can handle extremely wide fluctuations in heating load, which can easily adjust calorific value, and which produces less combustion noise. Now you can.

〔Example〕

Next, an example will be shown with reference to FIGS. 1 to 4.

The circular upward opening of the casing (1) is covered with a circular flat combustion surface forming wall (2), and an upwardly facing flat combustion surface (
2a) is formed by a wall (2).

A burner hole forming member (4) formed by arranging a large number of burner ports (3) in an annular manner toward the center of the wall (2) facing outward is attached to the wall (2).
2) The air-fuel mixer (5) is connected to the inside of the flame port forming member (4), and the mixed gas of the gas fuel and the primary air for combustion is applied to the combustion surface (2a). The flame ports (3) are arranged so as to emit flames in a radial direction along the direction.

A gas fuel supply pipe (6) with a flow rate control valve (V) is connected to the nozzle (5a) of the air-fuel mixer (5), and a secondary air supply path (7) formed at the back of the wall (2) is connected to the nozzle (5a) of the air-fuel mixer (5). ) electric fan (8)
are connected by an air supply path (9), and the air-fuel mixer (5) and the air supply path (9) are connected by a primary air supply port (10). In other words, the gas fuel from the supply pipe (6) and the primary combustion air from the electric fan (8) are premixed in the air-fuel mixer (5), and the mixed gas is supplied to the flame port (3). It is configured.

A large number of discharge ports (11) of the secondary air supply path (7) are formed in the shape of slits and are arranged radially on the combustion surface forming wall (2), and a number of discharge ports (11) are provided in the combustion surface forming wall (2). They are disposed close to both sides of each mixed gas jetting path and extending along the mixed gas jetting path. A porous dispersion device (12) such as a punched metal is provided inside the secondary air passage (7) so that the secondary air for combustion can be evenly supplied to the discharge port (11). Projections (13) arranged on both sides and extending over the entire length of the discharge port (11) are provided on the combustion surface forming wall (2) so as to protrude toward the combustion surface (2a).

In other words, the mixed gas ejected from the flame port (3) is combusted to form a flame at the flame port (3), the high temperature gas containing unburned content is made to flow along the combustion surface (2a), and the electric The combustion secondary air from the fan (8) is diffused and mixed with the high temperature gas from the discharge port (11), the unburned content in the high temperature gas is combusted, and the flame (F ).

When the input is low, a flame (F) is formed in the part of the combustion surface (2a) near the flame port (3) as shown in Figure 3, and as the input increases, the flame (F) becomes more combustible. The flame (F) extends to the outer periphery of the surface (2a), and when the input power is high, a flame (F) is formed over the entire or almost the entire combustion surface (2a) as shown in FIG. The apparent area of the upper burner area increases or decreases in direct proportion to the input, and regardless of wide fluctuations in input, the apparent area of the upper burner area decreases. In addition to increasing the maximum calorific value and turndown ratio and suppressing combustion noise, input adjustment can be easily performed with large changes in the flame formation range.

In addition, high-temperature gas from the flame port (3) flows along the combustion surface (2a) while being rectified by the protrusions (13), and secondary combustion air from the discharge port (11) flows protrusively. Article (13)
The high-temperature gas is ejected in a rectified state, and secondary air is gently mixed with the high-temperature gas, thereby further reducing combustion noise.

Tertiary air holes (14) are formed on the outer circumferential side of the wall (2) in positions corresponding to the discharge ports (11) for secondary air, and tertiary air for combustion is mixed in from the tertiary air holes (14). By,
The flame (F) is restrained from extending to the outside of the wall (2).

[Another example]

Next, another embodiment will be described.

The primary mixing configuration for supplying a mixed gas of gas fuel and primary air for combustion to the flame port (3) can be changed as appropriate.

The shape of the combustion surface forming wall (2) can be changed as appropriate,
For example, as shown in FIG. 5(a), the combustion surface (2a) is formed by an inclined surface that becomes higher as the distance from the flame port (3) increases, or as shown in FIG. 5(b), the combustion surface (2a) 3) The combustion surface (2a) may be formed with a curved surface whose rate of rise increases as the distance from It's okay,
In short, it is sufficient if a flat combustion surface (2a) is formed. The direction of the combustion surface (2a) may be downward or slightly inclined.

The number, arrangement, and shape of the flame ports (3) can be changed as appropriate. For example, as shown in Figure 6 (a), the flame ports (3) can be placed on the combustion surface (
2a) may be arranged so that the mixed gas is ejected toward the center of the combustion surface (2a), and as shown in FIG. ) may be arranged so that the mixed gas is ejected to the left and right.As shown in Figure 6 (c), the mixed gas may be placed in the center of the combustion surface (2a) with the flame port (3) on one end side of the combustion surface (2a). It may be arranged so that the flame is ejected to the other end side, and as shown in FIG.
A) may be arranged at both ends so that the mixed gas is ejected toward the center. However, when using a surface combustion burner as a stove, as in the above embodiment, a large number of flame ports (3)
are arranged in an annular shape facing outward toward the center of the round combustion surface forming wall (2) facing upward, so that the flame formation range can be selected in accordance with the size of the object to be heated, such as tin. This is desirable.

The secondary air discharge ports (11) may be disposed intermittently along the mixed gas jetting path. When the discharge ports (11) are arranged radially and the flame port (3) is arranged in the center as in the above-mentioned embodiment, the discharge ports (11) are loosely meandering on the outer end side where the interval between them is large. The actual discharge port (11)
If the interval is made small, sufficient secondary air mixing can be achieved even at the front end of the flame (F) at high input, and combustion efficiency can be improved. Moreover, the protrusions (13) on both sides of the discharge port (11)
) may be omitted.

The specific configuration of the surface combustion burner can be modified as appropriate.

The gas fuel used may be city gas, natural gas, propane gas, or any other fuel.

Note that although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structures and methods shown in the accompanying drawings.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a sectional view, FIG. 2 is a top view, and FIGS. 3 and 4 are explanatory diagrams of combustion states. 5 and 6 show different embodiments of the present invention, and FIGS. 5(a) and 5(b) are sectional views of main parts,
Figure 6 (a) or 2) is a top view. FIG. 7 is a sectional view of a conventional example. (2)...Wall body for forming combustion surface, (2a)...
... combustion surface, (3) ... flame mouth, (7) ...
... Secondary air supply path, (8) ... Electric fan, (11) ... Secondary air discharge port.

Claims (1)

[Claims] 1. A surface combustion burner having a flat combustion surface (2a) facing upward or downward, which directs a mixed gas of gas fuel and primary air for combustion in a direction along the combustion surface (2a). A secondary air supply path (7) is provided with a flame outlet (3) that blows out and supplies secondary air for combustion from an electric fan (8) to the wall (2) forming the combustion surface (2a). The discharge port (11) of the secondary air supply path (7) is arranged in the combustion surface forming wall (2) on both sides of the mixed gas jetting path from the flame port (3). and a surface combustion burner that is formed continuously or intermittently along the mixed gas ejection path. 2. The combustion surface forming wall (2) is formed in a round shape and faces upward, and a large number of the flame ports (3) are arranged toward the center of the round combustion surface forming wall (2) and facing outward. The surface combustion burner according to claim 1, wherein the secondary air supply outlet (11) is arranged radially.