JP2702027B2 - Surface burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface combustion burner, and more particularly, to preventing a so-called lift phenomenon of a flame caused by entrainment of air from around the burner.
The present invention relates to a surface combustion burner that enables high-load combustion in a burner plane.

[0002]

2. Description of the Related Art Conventionally, a flat porous member made of ceramic, for example, having front and back communicating pores sufficient for diffusion of a combustion gas mixture has been provided. Surface burners are known in which the mixture reaches the front surface of the planar porous member while diffusing, and is ignited and burned near the front surface. This type of surface combustion burner heats a planar porous member to glow,
Most of the energy is emitted as radiant heat, and the thermal conductivity of porous members such as ceramics is usually small, and even if the combustion temperature on the front surface is considerably increased, the temperature on the back surface does not rise so much. It is used not only in household combustion equipment but also in a wide range of fields as a safe burner that can prevent the generation of heat and has high thermal efficiency.

A typical configuration of a surface combustion burner will be described with reference to FIG. 4. In the surface combustion burner 10 shown in FIG. 2, a square or circular planar porous member 11 is
It is mounted on the front side of a cylindrical casing 13 via a heat-resistant packing 12. The front end of the casing 13 is bent inwardly in an L-shaped cross section to form a flange 14. The flange 14 covers the vicinity of the peripheral edge of the porous member 11 with a fixed width, thereby locking the porous member 11. Then, the positioning in the forward direction is performed.

[0004] The porous material 11 is usually a sintered body of a long fiber made of an alloy such as iron, chromium, silicon, aluminum, yttrium and the like, and has heat resistance of 1200 ° C or more. A packing having high heat resistance like a ceramic fiber sheet is similarly used. Inside the casing 13, there is a combustion gas distribution means 20 for diffusing the combustion gas mixture and uniformly distributing it on the back surface of the planar porous member 11. The combustion gas distribution means 20 is made of the same material as the casing 13, and includes a baffle plate 21 positioned parallel to the planar porous member 11 and an annular member 22 fixed to an outer peripheral portion of the baffle plate 21 by appropriate means. Has become. The annular member 22 includes
It has a U-shaped cross-sectional shape as shown in FIG.
A circulation path 26 is formed therein, and a plurality of openings 24 and 25 are formed in the inner peripheral wall portion 23 at the front and rear sides with the baffle plate 21 interposed therebetween. Annular member 22
Has the same outer peripheral shape as the inner peripheral wall portion of the casing 13 and is pressed into the casing 13 from the rear, pressing the rear surface of the planar porous member 11 against the front surface thereof against the casing flange 14. We support in state to do.

The combustion gas distribution means 20 includes a casing 13
Is supported by a back plate 30 having the same shape as that of the inner peripheral wall portion. The outer peripheral edge of the back plate 30 forms a bent portion 31, and the front end of the bent portion 31 and the rear end of the casing 13 are weld-stopped 35 over the entire circumference. Further, a cylindrical tube 32 is fixed to a central portion of the back plate 30 by an appropriate means, and the cylindrical tube 32 is connected to a combustion gas supply source via an appropriate piping means (not shown).

Accordingly, the casing 13, the planar porous member 11, and the back plate 30 form a mixed gas chamber 40, which is a closed space, and the mixed gas chamber 40 has an annular shape that constitutes the combustion gas distribution means 20. Member 22 and casing 13
, The front mixed gas chamber 41 defined by the planar porous member 11 and the baffle plate 21, and the rear mixed gas chamber 42 defined by the baffle plate 21 and the back plate 30. It is divided into and.

The combustion of the surface combustion burner is performed as follows. A combustion gas mixture from a suitable gas source is pressed into the rear mixed gas chamber 42 from the cylindrical member 32. The press-fitted combustion gas mixture collides with the baffle plate 21 and changes its flow direction, enters into the circulation path 26 through an opening 25 provided in the inner peripheral wall portion 23 of the annular member 22, and changes direction again there. Flows into the front mixed gas chamber 41. During that time, the combustion gas and air are thoroughly mixed and homogenized. The homogenized combustion gas mixture passes through the continuous pores from the back surface of the planar porous member 11 to the front surface, and reaches the front surface of the porous member 11 excluding the portion covered by the flange 14 of the casing 13 described above. It is ignited and burns. By the combustion, the front surface of the planar porous member 11 becomes incandescent and emits radiant heat.

[0008]

The surface combustion burner as described above is extremely effective from the viewpoint of effective use of heat and safety. However, when attempting to perform high-load lean combustion by increasing the air ratio, a flame lift phenomenon occurs and the combustion becomes unstable.Therefore, high-load combustion beyond a certain limit cannot be performed, and the combustion load naturally falls within the combustion load range. Restrictions were imposed. Further, when the high-load operation to the extent permitted, normally the range from becoming a relatively No occurrence of _x easy, improved environmental surfaces has been required along with the improvement of combustion load.

An object of the present invention is to solve the above-mentioned disadvantages of the conventional surface combustion burner, to enable high-load lean combustion in a stable state, thereby performing stable combustion in a wide combustion load range. lies in obtaining a surface combustion burner that can, still another object is low No _x
An object of the present invention is to provide a compact surface-burning burner capable of burning.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have intensively studied the lift phenomenon. As a result, the lift phenomenon in the planar combustion burner does not occur uniformly over the entire combustion surface, but occurs early and frequently on the outer peripheral edge of the combustion surface, and the lift generated on this peripheral edge He perceived that the phenomena affected the combustion flame more inside and contributed to the lift. This is presumably due to the phenomenon that the flame causes the entrainment of the surrounding air at the outer peripheral edge of the combustion surface, thereby causing a further lift phenomenon.

The present invention has been made on the basis of the above analysis, and includes a porous member forming a combustion surface on the front surface, a casing extending rearward from a rear surface near the outer periphery of the porous member, and a porous member. Combustion chamber having a mixed gas chamber formed of a quality member and a casing, and an opening for supplying a combustion gas mixture to the mixed gas chamber, wherein the mixed gas chamber is located at a central portion by a partition wall. Disclosed is a surface combustion burner, which is divided into a mixed gas chamber and a second mixed gas chamber located on the outer periphery thereof, and each of the mixed gas chambers is provided with an opening for supplying a combustion gas mixture. .

[0012] The porous member may be configured such that a porosity of a portion facing the first mixed gas chamber is higher than a porosity of a portion facing the second mixed gas chamber. Thereby, higher load combustion can be performed in a state where the occurrence of a lift is prevented. It is also effective to form a large number of through holes in a portion of the porous member facing the first mixed gas chamber.

As the material for the casing, the porous member and the like constituting the burner according to the present invention, the material used for the conventional burner can be used as it is.

[0014]

When the surface combustion burner of the present invention is used, combustion gas mixtures having different air ratios are supplied to the first mixed gas chamber and the second mixed gas chamber. For example, the first mixed gas chamber facing the central portion of the porous body contains an excess air-fuel mixture (for example, an air ratio of 1.3
From about 2.0), and at the same time, the second mixed gas chamber, which is located so as to surround the outer periphery of the first mixed gas chamber, has a structure in which the porous member is incandescent or the flame becomes a lean blue flame. Supply a mixture (for example, an air ratio of about 1.0 to 1.2).

As a result, red and blue flame combustion occurs in the peripheral portion of the porous member to maintain a stable combustion state, while high load lean blue flame combustion is performed in the inner portion. At that time, despite the high-load lean combustion, the peripheral portion of the flame continues to be burned by the stable flame, so that the air is completely trapped in the high-load lean-burn portion from that portion. As a result, it is possible to maintain a high-load lean-burn flame in a stable state, that is, in a state where the lift phenomenon does not occur, for a long period of time. In other words, stable combustion can be performed in a wide combustion load range.

As a result, No._xGreatly reduces the occurrence of
And with the same combustion area compared to conventional ones
Because it is possible to obtain a large combustion load,
It is also possible to make the whole compact. FIG.
Is a conventional flat combustion burner of the type shown in FIG.
Using the same combustion gas mixture as a planar combustion burner
Lift of both burners when actually performing a combustion experiment
The limit line is shown (Note that the air ratio depends on the number of burners used.
This is a value measured at the center of the porous member). From the figure,
Akira's plane burner burns at similar air ratios
Combustion conditions up to higher combustion load conditions
It can be seen that can be maintained. The bag used in this experiment was
The voids in the porous body attached to the cavity are substantially evenly distributed.
The porosity was 96% and the surface area was 13%.
2cm^TwoIn the case of "only porous body", all
Supply a combustion gas mixture with an air ratio of 1.3 to 2.0 to the surface area,
In the case of "according to the present invention", about 95 cm in the center^Two Against
Combustion gas mixture with the same air ratio as in "porous body only"
Supply, about 37cm around^TwoLower air for
This is the result of an experiment conducted by supplying a combustion gas mixture having a ratio of 1: 1.
You.

[0017]

Hereinafter, the present invention will be described in more detail based on the description of one embodiment. FIG. 1 shows a sectional view of one embodiment of a surface combustion burner 1 according to the present invention. In this surface combustion burner 1, the casing 2 has a bottomed cylindrical shape with the front open, and a first cylindrical pipe 4 is provided at an appropriate location on the bottom 3 and an appropriate location is provided on the cylindrical peripheral wall. Has a second
Are fixed by appropriate means, respectively, and the cylindrical pipes 4 and 5 are connected to a combustion gas supply source via pipe means described later.

The open front end of the casing 2 forms an enlarged diameter portion 6 having a constant depth.
Is provided with a plurality of openings 7,7. In the casing 2, a cylindrical partition 8 having a smaller diameter is fixed to the bottom 3 of the casing 2 by a suitable means. The partition 8 has the same height as the lower end of the enlarged diameter portion 6 of the casing 2.

A porous member 11 is fed into the enlarged diameter portion 6 of the casing 2 and is integrally attached to the casing 2 via bolts and nuts by a holding member 50 having an opening in the periphery. Although not particularly shown, a heat insulating packing may be interposed between the porous member 11 and the pressing plate 50. In the case of the planar combustion burner having such a configuration, FIG.
Unlike conventional burners as shown in
A first mixed gas chamber defined by the bottom 3 of the casing 2, the inner wall of the partition 8, and the porous member 11, and the bottom 3 of the casing 2 and the outer wall of the partition 8 located on the outer periphery thereof And the inner wall of the cylindrical peripheral wall of the casing 2 and the porous member 1
It is divided into a second gaseous mixture chamber partitioned by 1, the mixed
The gas chambers are independent of each other. Accordingly, the combustion gas mixture flowing from the cylindrical tube 4 passes through the central portion of the porous member from the first mixed gas chamber and burns on the surface thereof, and the combustion gas mixture flowing from the cylindrical tube 5 becomes the second gas mixture. The gas passes through the peripheral portion of the porous member from the mixed gas chamber and burns on the surface thereof. In the combustion process, the respective gas mixtures hardly mix.

FIG. 2 shows an embodiment of a piping system using the surface combustion burner according to the present invention. Gas pipe a connected to a suitable combustion gas supply source (not shown) is bifurcated, one is connected to the first cylindrical tube 4 communicating with the first mixed gas chamber through a flow control valve v ₁ and the other is connected to the second cylindrical tube 5 which communicates with the second gas mixture chamber via a flow control valve v ₂ as well. Further, bifurcated similarly air pipe b which is connected to an air supply source appropriately, not shown, one connected to the first cylindrical tube 4 communicating with the first mixed gas chamber through a flow control valve va ₁ and the other is connected to the second cylindrical tube 5 which communicates with the second gas mixture chamber via a flow regulating valve va ₂ as well.

When the surface combustion burner of the present invention is used by using the piping system having the above-described structure, the gas pipe a and the air pipe b are supplied from an appropriate supply source according to the use environment of the burner.
The combustion gas and air supplied to the flow regulating valve v _1, v _2,
By appropriately adjusting va ₁ and va ₂ , different air ratios are simultaneously supplied to the first and second mixed gas chambers.
Accordingly, as described above, by setting the air ratio of the combustion gas mixture supplied to the first mixed gas chamber to a value higher than the air ratio of the combustion gas mixture supplied to the second mixed gas chamber. , Preferably by setting the former air ratio to about 1.3 and the latter air ratio as 1.1 to perform combustion,
Compared with the conventional, it is possible to perform a long time a high load lean combustion under conditions generate less of No _x.

The above description is merely one embodiment of the present invention, and there are many other modifications. The overall shape of the casing is not limited to a cylindrical shape, but may be a square shape or an elliptical shape, and the partition partitioning the first and second mixed gas chambers may have any shape.
Also, the volume ratio of the first and second mixed gas chambers, or the first
And the surface area ratio of the porous member facing the second mixed gas chamber,
The optimum ratio can be experimentally determined according to the use environment of the burner without being limited to the above ratio.

Although not shown, the porosity of the portion of the porous member facing the first mixed gas chamber is set to be higher than the porosity of the portion facing the second mixed gas chamber. In that case, high load combustion and low pressure loss effects can be obtained. Further, a large number of through-holes may be formed in the portion of the porous member facing the first mixed gas chamber, and in this case, high load combustion and low pressure loss can be obtained.

[0024]

Since the surface combustion burner of the present invention has the above-mentioned structure, a combustion gas mixture having a different air ratio is supplied to the central portion and the peripheral portion of the porous member which is the combustion surface. it becomes possible, by appropriately selecting the respective air ratio, compared with the conventional, it is possible to perform a long time a high load lean combustion under conditions generate less of No _x.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of a surface combustion burner according to the present invention.

FIG. 2 is an explanatory view showing one embodiment of a piping means for supplying a combustion gas mixture.

FIG. 3 is a graph showing a comparison when a lift occurs.

FIG. 4 is a cross-sectional view of a conventional surface combustion burner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Surface combustion burner, 2 ... Casing, 3 ... Bottom part of casing, 4 ... Cylindrical tube, 8 ... Partition wall, 11 ... Porous material,

Claims (3)

(57) [Claims] 1. A porous member constituting a combustion surface on a front surface;
A casing extending rearward from the rear surface near the outer periphery of the porous member, a mixed gas chamber formed by the porous member and the casing, and an opening for supplying a combustion gas mixture to the mixed gas chamber. The mixed gas chamber is divided into a first mixed gas chamber located at a central portion by a partition wall and a second mixed gas chamber located at an outer periphery thereof, and a combustion gas mixture is supplied to each mixed gas chamber. Surface burners, characterized in that openings are provided for each of the burners. 2. The porous member is configured such that a porosity of a portion facing the first mixed gas chamber is higher than a porosity of a portion facing the second mixed gas chamber. The surface combustion burner according to claim 1, characterized in that: 3. The surface combustion burner according to claim 2, wherein a number of through holes are formed in a portion of said porous member facing said first mixed gas chamber.