JP2573197Y2 - 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 having a porous member constituting a combustion surface on the front surface, and in particular, to perform high load combustion by penetrating a large number of through holes in the porous member. A surface-burning burner suitable for:

[0002]

2. Description of the Related Art Conventionally, for example, a flat porous member made of ceramic, for example, having front and back communicating pores, and a mixed gas chamber provided behind the porous member are provided. A surface combustion burner is known, in which a mixed gas composed of fuel gas and combustion air reaches a front surface thereof while diffusing through a porous member, and is ignited and burned near the front surface. ing. This type of surface combustion burner heats a porous member to make it glow and emits most of the energy as radiant heat. In addition, the thermal conductivity of a porous member such as ceramic is usually small and the combustion temperature of the surface is small. Even if is considerably increased, the temperature of the back side does not rise so much,
As a safer burner with high thermal efficiency that can prevent the occurrence of flashback, it is used not only in household combustion equipment but also in a wide range of fields.

[0003] Such a surface combustion burner having a combustion surface made of a porous member has less of a problem of occurrence of flashback as compared with a structure in which a large number of through holes are provided in a non-permeable ceramic plate. However, since the mixed gas passes through the small pores of the porous member over substantially the entire surface at the same speed, when high-load combustion is performed, the ejection speed of the mixed gas passing through the pores increases, and a flame is generated. There is a problem that it is easy to fly by discontinuous lifting.

Therefore, in order to stably perform high-load combustion in such a surface combustion burner, the mixed gas chambers provided behind the planar porous member correspond to the central portion and the peripheral portion of the combustion surface, respectively. Partition the interior so that
By supplying the mixed gas with different air ratios and flow rates, the combustion state at the front of the porous member is made different between the center and the periphery, and the height of the center is increased by stable combustion at the periphery. It has been proposed to assist load lean combustion to stabilize overall combustion.

More specifically, such a surface combustion burner will be described with reference to FIGS. 1 and 2. A circular planar porous member 1 is provided on the front side of a cylindrical casing 2.
Is mounted via a heat-resistant packing or the like. A cylindrical partition wall 3 is provided inside the cylindrical casing 2 concentrically with the casing 2, and the rear side thereof is a back plate 4. It is closed by

As a result, in the interior of the cylindrical casing 2, a central mixed gas chamber 5, which is a closed space, is formed by the partition wall 3, the central portion 11 of the planar porous member 1, and the back plate 4. The peripheral mixed gas chamber 6, which is another closed space, is formed by the casing 2, the peripheral portion 12 of the planar porous member 1, and the back plate 4 so as to surround the outer peripheral portion of the central mixed gas chamber 5.

[0007] Mixed gas supply pipes 71 and 72 branched from one cylindrical pipe 7 communicating with a supply source of combustion air are fixed to a central portion of the back plate 4 and the casing 2 by appropriate means. Mixed gas supply pipe 71,
Reference numeral 72 designates a flow regulating valve 9 for combustion air at its upstream portion.
1 and 92 are provided respectively. Further, on the side wall of each of the mixed gas supply pipes 71 and 72, a fuel gas inlet 7 is provided downstream of the combustion air flow control valves 91 and 92.
The fuel gas inlets 73 and 74 are branched from one cylindrical pipe 8 communicating with the fuel gas supply device, and each of the fuel gas inlets 73 and 74 is opened.
Fuel gas supply pipes 81 and 82 having fuel gas flow control valves 93 and 94 are connected to upstream portions of the fuel gas supply pipes 3 and 74, respectively.

When such a surface combustion burner is to be burned, the respective mixed gas supply valves are adjusted by appropriately adjusting the flow control valves 91 and 92 of the combustion air and the flow control valves 93 and 94 of the fuel gas. Since mixed gases having different air ratios can be respectively sent from the pipes 71 and 72 to the central mixed gas chamber 5 and the peripheral mixed gas chamber 6 at different flow rates, the mixed gas having a high air ratio is supplied to the central mixed gas chamber 5. By supplying a large amount of gas, high-load lean combustion is performed at the corresponding central portion 11 of the planar porous member 1 while the peripheral mixed gas chamber 6 has an air ratio and amount suitable for stable combustion. By supplying the mixed gas, stable combustion is performed in the peripheral portion 12 of the planar porous member 1 corresponding thereto, and high load lean combustion in the central portion 11 can be stabilized by stable combustion in the peripheral portion 12.

Furthermore, conventionally, in a surface combustion burner in which a front surface of a porous member having a large number of pores communicating with each other is used as a combustion surface, the porous member has a uniform hole shape having a diameter of 0.05 to 5.0 mm. By penetrating a large number of through holes substantially perpendicularly to the combustion surface of the porous member at intervals of 2 to 3 mm, the mixed gas is ejected to the surface of the porous member through the through holes,
There is also known a technique in which high load combustion is enabled by burning a large amount of gas by performing main combustion (Japanese Utility Model Application Laid-Open No.
-63524).

[0010] In this case, since a large amount of mixed gas is ejected to the surface of the porous member through the through holes by penetrating a large number of through holes in the porous member, in the case of high load combustion, the gas passes through the pores. The jet velocity of the mixed gas does not become so large that the flame is lifted by discontinuous lifting and blows away.The long flame caused by the combustion of the mixed gas injected from the through-hole portion and the mixed gas passing through the pores of the porous member in between , A stable continuous flame is formed.

[0011]

[Problems to be solved by the invention] By the way, FIG.
And the combustion state at the front surface of the porous member is different between the central portion and the peripheral portion as described with reference to FIG. 2, and the high-load lean combustion at the central portion is assisted by stable combustion at the peripheral portion. Also in the burner, when performing high-load lean combustion, the stable combustion range is 80% when the air ratio is 1.2.
It was about 00 kW / m ² or the limit.

In order to stably perform the combustion itself in the high-load lean combustion region over a wider combustion load range, a technique has been proposed in which a large number of through holes are provided in the high-load lean combustion region of the porous member. However, the diameters of the conventional through-holes are all the same, and if the diameter of the through-holes is made smaller, when the combustion load is further increased, the mixed gas from the through-holes is reduced. If the jet flow velocity becomes large on the whole, causing a blow-off phenomenon, the combustion becomes unstable, and if the diameter of the through hole is made large,
When the combustion load is reduced, the concentration of the mixed gas in the through-holes becomes excessive, and the surface combustion temperature in the through-hole portion and the pore portion therebetween is likely to be non-uniform. However, the combustion load range in which stable combustion can be performed cannot be so widened.

In the surface combustion burner having a porous member constituting a combustion surface on the front surface, in order to widen the combustion load range, the cross-sectional area of the through-hole provided on the combustion surface side is set to the cross-sectional area at the center. Larger than the one described in
(Japanese Patent Application Laid-Open No. Sho 80-80417) and those in which the average pore diameter of the portion forming the combustion surface of the porous member is larger than the average pore diameter of the portion facing the mixed gas inlet side.
And a mixed gas passing through a through-hole provided through and a mixed gas passing through a pore of a porous member are supplied from different supply sources while changing the air ratio. No. 61-106728) have been proposed in the past, but none of them has a complicated configuration itself and can not be applied to any surface combustion burner.

An object of the present invention is to solve the above-mentioned disadvantages of the conventional surface combustion burner. More specifically, the present invention has a plurality of through-holes penetrating a porous member constituting a combustion surface on the front surface. By making the holes have a fixed pattern consisting of several types of through holes with different diameters, the jet flow velocity of the mixed gas is partially changed on the combustion surface, and the combustion load changes in several stages. In each case, any part on the combustion surface is assumed to have a relatively stable flame zone, and the relatively stable flame zone stabilizes the surrounding unstable combustion part, so that a wide area is obtained. An object of the present invention is to stably perform high-load lean combustion in a combustion load range, thereby suppressing generation of nitrogen oxides.

[0015]

Means for Solving the Problems In order to solve the above-mentioned problems and achieve the object, the present invention basically comprises a porous member having a large number of pores communicating with each other on the front and back, and a rear portion of the porous member. A mixed gas chamber provided in the mixed gas chamber, wherein the mixed gas supplied to the mixed gas chamber is passed through the front surface of the porous member, and the mixed gas is burned using the front surface as a combustion surface. The mixed gas chamber is divided into two parts, a central part and a peripheral part, so that mixed gas in different states can be separately supplied to the mixed gas chamber. The combustion surface on the front surface of the porous member is the mixed gas chamber. Is divided into a stable combustion region in the peripheral portion and a high-load lean combustion region in the central portion, and the high-load lean combustion region in the central portion of the porous member has a diameter larger than the pores of the porous member. A large number of through holes having Hole, characterized in that it consists of several through holes having different diameters.

[0016]

The combustion of the surface combustion burner of the present invention is performed as follows. That is, the mixed gas in which the fuel gas and the combustion air are mixed is pumped into the mixed gas chamber, passes through the porous member, reaches the surface thereof, is ignited, and burns. Since the gas passes through the porous member through each of several types of through holes having different diameters from the pores of the porous member, the jet flow velocity of the mixed gas on the surface of the porous member depends on the number of stages depending on each part of the surface. It will be in a changed state. Therefore, even if the combustion load changes, any portion on the combustion surface has a relatively stable flame region each time, and the stable flame region stabilizes the unstable combustion portion around it. It will be.

[0017]

Hereinafter, the present invention will be described in more detail based on the description of the embodiments. The surface combustion burner in each of the following embodiments has the same configuration as that shown in FIGS. 1 and 2 except for the configuration of the planar porous member 1. Detailed description is omitted.

FIGS. 3 and 4 show the structure of the planar porous member 1 in each embodiment of the present invention, and are applied to the surface burning burner as shown in FIGS. You. That is, the planar porous member 1 is formed by accumulating thin glass fibers in a nonwoven fabric shape, and has a large number of pores of about 100 μm. This planar porous member 1
Covers both the high-load lean combustion region of the central portion 11 corresponding to the central mixed gas chamber 5 of the surface combustion burner and the stable combustion region of the peripheral portion 12 corresponding to the peripheral mixed gas chamber 6. , In the high-load lean-burn region of the central part 11
A plurality of through-holes 13 whose diameter is larger than the pores of the porous member are formed substantially perpendicularly to the surface thereof, and the plurality of through-holes 13 are formed of several types of through-holes having different diameters. It is arranged by. Basically, the arrangement of several types of through-holes having different diameters may be random, but it is a preferred embodiment that they are patterned with predetermined regularity.

First, in the embodiment shown in FIG. 3, three kinds of through holes 13A having different diameters are formed in the central portion 11 of the circular flat porous member 1 which is a high-load lean burn region.
(D1.0-P2.5), 13B (D3.0-P5.
0) and 13C (D5.0-P7.5) are arranged in the order of ABCA from the center of the porous member toward the outer periphery, and the diameter of the through-hole 13 is stepwise. The through holes are provided in a changing pattern (D is the diameter of the through hole, and P is the average distance between the centers of the through holes).

Next, in the other embodiment shown in FIG. 4, similarly, in the central portion 11 of the circular flat porous member 1 which is a high-load lean burn region, two kinds of through holes 13D having different diameters are formed. D1-P5) and 13E (D5-P10)
The small-diameter through-holes 13D are scattered around the large-diameter through-holes 13E in a pattern. Regarding the stable combustion limit of each surface combustion burner having the flat plate porous member 1 in which the through-hole is penetrated in each pattern, similarly to the above-mentioned respective embodiments, the stable combustion region in the peripheral portion and the height located inside the stable combustion region are determined. An experiment was conducted in comparison with a surface combustion burner having a load-lean combustion region and having a flat plate porous member having through holes (D1.0-P2.5) of uniform size penetrated in the high-load lean-burn region. The results are as shown in FIG. 5 (note that the pattern shown in FIG. 3 is described as hole pattern 1 and the pattern shown in FIG. 4 is described as hole pattern 2). It can be seen that the surface combustion burner according to the present invention has a clearly improved stable combustion limit as compared with the conventional one.

[0021]

[0022]

The surface combustion burner according to the present invention has a simple structure in which several types of through-holes having different diameters are pierced through a porous member in accordance with a fixed pattern, so that it can be used on a combustion surface in a high-load lean burn region. The jet velocity of the mixed gas can be partially changed. As a result, even when the combustion load changes, any part of the combustion surface can form a stable combustion region, and the stable combustion region stabilizes the surrounding unstable combustion portion. Can be done. This makes it possible to stably perform high-load lean combustion in a wide combustion load range, and to suppress generation of nitrogen oxides.

[Brief description of the drawings]

FIG. 1 is a perspective view of one embodiment of a surface combustion burner to which the present invention is applied.

FIG. 2 is a sectional view of the surface combustion burner shown in FIG. 1;

FIG. 3 is a front view of the porous member according to the embodiment of the present invention;

FIG. 4 is a front view of a porous member according to another embodiment of the present invention.

FIG. 5 is a comparison graph of the stable combustion limit between each embodiment of the present invention and a conventional example.

[Explanation of symbols]

 1-porous member 5-mixed gas chamber (central part) 6-mixed gas chamber (peripheral part) 11-porous member central part (high-load lean burn area) 12-porous member peripheral part (stable combustion area) 13 -Through hole

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-3407 (JP, A) JP-A-63-17309 (JP, A) JP-A-52-37236 (JP, A) 134221 (JP, U) JP-A 63-134220 (JP, U) JP-A 63-134222 (JP, U) JP-A 42-15733 (JP, Y1) (58) Fields surveyed (Int. ⁶ , DB name) F23D 14/00-14/18 F23D 14/26-14/84

Claims (3)

(57) [Scope of request for utility model registration] A porous member having a large number of fine pores communicating with each other, and a mixed gas chamber provided behind the porous member. In the surface combustion burner, in which the mixed gas is burned by passing the mixture to the front surface of the member and burning the mixed gas with the front surface as a combustion surface, the mixed gas chamber is provided with a central portion so that mixed gas in different states can be separately supplied thereto. The combustion surface in front of the porous member is divided into a stable combustion region in a peripheral portion of the mixed gas chamber and a high-load lean combustion region in a central portion of the mixed gas chamber. A large number of through holes having a diameter larger than the pores of the porous member are provided in the high-load lean burn region in the central portion of the porous member, and the large number of through holes have several types having different diameters. Surface burner characterized by comprising through holes . 2. The method according to claim 1, wherein the plurality of through-holes penetrating through the porous member have a pattern in which the diameter is gradually changed from the center of the porous member toward the outer periphery. The surface combustion burner according to claim 1. 3. The method according to claim 1, wherein the large number of through holes provided through the porous member are patterns in which small diameter through holes are arranged around large diameter through holes. Surface burning burner.