JPH0596724U - Surface burning burner - Google Patents

Abstract

(57) [Summary] [Purpose] In a surface combustion burner, by stabilizing the unstable combustion part around it by its relatively stable flame region, stable high-load lean combustion is achieved in a wide combustion load range. And suppress the generation of nitrogen oxides. [Structure] A porous member having a large number of pores and a mixed gas chamber provided behind the porous member are provided, and the mixed gas sent to the mixed gas chamber is passed through the front surface of the porous member. In a surface combustion burner in which a mixed gas is combusted with the front surface thereof as a combustion surface, at least two or more kinds of penetrating the porous member 1 are formed substantially perpendicular to the surface and have a diameter larger than the pores of the porous member. A large number of holes 13A, 13B, 13C are provided through.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a surface combustion burner having a porous member forming a combustion surface on the front surface, and particularly to a surface combustion burner suitable for performing high load combustion by penetrating a large number of through holes in the porous member. Regarding burners.

[0002]

[Prior Art]

 Conventionally, a planar porous member made of, for example, ceramic having pores communicating with the front and back and a mixed gas chamber provided behind the porous member, and a fuel gas fed to the mixed gas chamber, A surface combustion burner is known in which a mixed gas including combustion air passes through a porous member, diffuses, reaches the front surface thereof, and is ignited and burned in the vicinity of the front surface. This type of surface combustion burner heats and incandescently heats the porous member, and releases most of the energy as radiant heat, and the thermal conductivity of a porous member such as a ceramic is usually small, and Since the backside temperature does not rise much even if the combustion temperature is raised considerably, it is used as a safe burner with high thermal efficiency that can prevent the occurrence of flashback, and is used in a wide range of fields, not limited to household combustion equipment. ..

A surface combustion burner having a combustion surface made of such a porous member is less likely to cause a flashback as compared with a ceramic plate having no air permeability and a large number of through holes. However, since the mixed gas passes through the small pores of the porous member almost all over at the same speed, when high-load combustion is performed, the jet speed of the mixed gas passing through the pores increases. However, there is a problem that the flame is discontinuously lifted and easily blown off.

Therefore, in order to stably perform high-load combustion in such a surface-combustion burner, the mixed gas chambers provided behind the flat porous member correspond to the central portion and the peripheral portion of the combustion surface, respectively. As described above, the inside of the porous member is partitioned, and the mixed gas is fed to each in a state where the air ratio and the flow rate are different, so that the combustion state at the front surface of the porous member is different between the central portion and the peripheral portion, It has been proposed that stable combustion in the peripheral area assists high-load lean combustion in the central area to stabilize the overall combustion.

The surface combustion burner will be described in more detail with reference to FIGS. 1 and 2. In the front side of the cylindrical casing 2, a circular planar porous member 1 is provided with heat-resistant packing or the like. A cylindrical partition wall 3 is provided inside the cylindrical casing 2 concentrically with the casing 2, and its rear side is closed by a back plate 4.

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

Mixed gas supply pipes 71 and 72 branched from one cylindrical pipe 7 leading to a supply source of combustion air are fixed to the central portion of the back plate 4 and the casing 2 by appropriate means. The mixed gas supply pipes 71 and 72 are provided with combustion air flow rate adjusting valves 91 and 92, respectively, at their upstream portions. Further, fuel gas inlets 73 and 74 are opened on the side walls of the mixed gas supply pipes 71 and 72, respectively, on the downstream side of the flow rate adjusting valves 91 and 92 of the combustion air, respectively. Each of the fuel gas inlets 73 and 74 is branched from one cylindrical pipe 8 leading to the fuel gas supply device, and the flow rate of the fuel gas is adjusted upstream of the respective fuel gas inlets 73 and 74. Fuel gas supply pipes 81 and 82 having valves 93 and 94 are connected to each other.

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

Further, 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 on the front and back sides is a combustion surface, the porous member has a uniform pore shape with a diameter of 0.05 to 5.0 mm. By forming a large number of through holes at a distance of 2 to 3 mm approximately perpendicular to the combustion surface of the porous member, the mixed gas is ejected to the surface of the porous member through the through holes, and main combustion is performed to generate a large amount of gas. There is also known a technique of making it possible to perform high-load combustion by burning (see Japanese Utility Model Publication No. 62-63524).

Regarding this, by providing a large number of through-holes in the porous member, a large amount of mixed gas is ejected to the surface of the porous member through the through-holes. The jet speed of the mixed gas that passes through does not increase so much that the flame discontinuously lifts and blows, and the long flame due to the combustion of the mixed gas jetted from the through-hole portion and the passing through the pores of the porous member in between. A stable continuous flame is formed by the short flame generated by the combustion of the mixed gas.

[0011]

[Problems to be solved by the device]

By the way, as described above with reference to FIGS. 1 and 2, the combustion state in the front surface of the porous member is made different between the central portion and the peripheral portion, and stable combustion in the peripheral portion ensures high-load lean combustion in the central portion. Even in the case of the surface combustion burner that assists, the stable combustion range is about 8000 kw / m ² when the air ratio is 1.2 when the high load lean combustion is performed.

[0012] Therefore, in order to stably perform combustion itself in a high load lean burn region over a wider combustion load range, a technique of providing a large number of through holes in the high load lean burn region of a porous member is proposed. However, all of the conventional through-holes have the same diameter, and if the diameter of the through-holes is small, the mixing from the through-holes will increase when the combustion load is further increased. The flow velocity of the gas is increased over the entire surface, which causes a blow-off phenomenon, resulting in unstable combustion. Also, if the diameter of the through hole is large, the penetration of the mixed gas is reduced when the combustion load becomes low. If the concentration in the holes becomes excessively large, unevenness of the surface combustion temperature will easily occur between the through-holes and the pores between them, and in any case, stable combustion can be performed. Load range It cannot be widened.

In addition, in a surface combustion burner having a porous member forming a combustion surface on the front surface, in order to widen the combustion load range, the cross-sectional area of the combustion surface side of the through-holes provided through Or the average pore diameter of the portion forming the combustion surface of the porous member is made larger than the average pore diameter of the portion facing the mixed gas inlet side. (Japanese Patent Application Laid-Open No. 62-80417) or mixed gas passing through the through-holes that are transparently provided and mixed gas passing through the pores of the porous member are supplied from different supply sources by changing the air ratio. The above-mentioned structure (Japanese Utility Model Laid-Open No. 61-106728) and the like have been proposed in the past, but all of them have complicated structures and cannot be applied to any surface combustion burner.

The present invention is intended to eliminate the above-mentioned disadvantages of the conventional surface combustion burner, and more specifically, a large number of porous members that are provided on the front surface of the porous surface to form the combustion surface. By making the through-holes have a certain pattern consisting of several kinds of through-holes with different diameters, the jet velocity of the mixed gas was partially changed on the combustion surface, and the combustion load changed in several steps. However, by making each part of the combustion surface have a relatively stable flame area in each case, and stabilizing the unstable combustion part around it by the relatively stable flame area, The purpose is to stably perform high-load lean combustion in a wide combustion load range and thus suppress the generation of nitrogen oxides.

[0015]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems and to 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 mixed gas chamber provided behind the porous member. In the surface combustion burner, the mixed gas sent to the mixed gas chamber is passed through the front surface of the porous member to burn the mixed gas with the front surface as a combustion surface. On the other hand, a large number of through-holes each having a diameter larger than the pores of the porous member are formed substantially vertically, and the large number of through-holes are composed of several kinds of through-holes having different diameters.

[0016]

[Action]

 Combustion of the surface combustion burner of the present invention is performed as follows. That is, the mixed gas of the fuel gas and the combustion air is pumped into the mixed gas chamber, passes through the porous material, reaches its surface, and is ignited and burned. Since the mixed gas passes through the porous member through each of the pores of the porous member and several kinds of through holes having different diameters, the jetting velocity of the mixed gas on the surface of the porous member depends on the number of steps depending on each part of the surface. It will be in a changed state. Therefore, even if the combustion load changes, any part of the combustion surface will have a relatively stable flame area, and that stable flame area will stabilize the unstable combustion area around it. Will be changed.

[0017]

【Example】

 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 examples has the same structure as that shown in FIGS. 1 and 2 except for the structure of the flat porous member 1, and therefore the same reference numerals are used for the same. Detailed description is omitted.

FIGS. 3 and 4 each show the configuration of the planar porous member 1 in each embodiment of the present invention, which is applied to the surface combustion burner as shown in FIGS. 1 and 2. It That is, the flat porous member 1 is made by accumulating thin glass fibers in a non-woven fabric, and has a large number of pores of about 100 μm. This planar porous member 1 has both a high-load lean combustion region in the central portion 11 corresponding to the central mixed gas chamber 5 of the surface combustion burner and a stable combustion region in the peripheral portion 12 corresponding to the peripheral mixed gas chamber 6. A large number of through-holes 13 are provided in the high-load lean-burn region of the central portion 11 of the region, which are substantially perpendicular to the surface of the region and whose diameter is larger than the pores of the porous member. In addition, the plurality of through holes 13 are arranged by several kinds of through holes having different diameters. Basically, the arrangement of several kinds of through holes having different diameters may be random, but it is a preferred embodiment that they are patterned with a predetermined regularity.

First, in the embodiment shown in FIG. 3, three kinds of through holes 13 A (D 1 having different diameters are provided in the central portion 11 of the circular flat plate porous member 1 which is the high load lean combustion region. .0-P2.5), 13B (D3.0-P5.0), and 13C (D5.0-P7.5) are referred to as A-B-C-A from the center of the porous member toward the outer peripheral portion. The through holes 13 are arranged in order, and the through holes 13 are transparently arranged in a pattern in which the diameter of the through holes 13 is changed stepwise (where D is the diameter of the through holes, and P is the average distance between the centers of the through holes). Is).

Next, regarding another embodiment shown in FIG. 4, similarly, in the central portion 11 which is the high load lean burn region of the circular flat plate porous member 1, two kinds of through holes 1 having different diameters are provided. 3D (D1-P5) and 13E (D5-P10) are transparently provided in a pattern in which small-diameter through holes 13D are scattered around a large-diameter through-hole 13E. Regarding the stable combustion limit of each surface combustion burner having the flat plate porous member 1 having the through holes penetratingly arranged in each pattern, the stable combustion limit of the peripheral portion and the inside thereof are the same as in the above embodiments. And a surface combustion burner having a flat plate porous member having through holes (D1.0-P2.5) of uniform size formed in the high load lean burn region. I did an experiment. The results are as shown in FIG. 5 (wherein 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 an improved stable combustion limit as compared with the conventional one.

Although the present invention has been described above based on the respective embodiments, the present invention is not limited to these embodiments, and for example, the surface combustion bar excluding the configuration of the flat porous member 1 is used. Regarding the structure of the core, not only the structure shown in FIGS. 1 and 2, but also other structures such as a structure without the partition wall 3 are applicable, and a pattern of through holes is also applicable. In other words, the point is that the through holes have a diameter larger than that of the pores of the porous member, and it is sufficient that two or more kinds of through holes having different diameters are scattered almost uniformly on the combustion surface. The patterns are not limited to the patterns shown in FIGS. 3 and 4, and various types of patterns may exist.

[0022]

[Effect of the device]

 The surface combustion burner according to the present invention has a simple structure in which several kinds of through-holes having different diameters are formed through a porous member in a fixed pattern. Can be partially changed. As a result, even if the combustion load changes, any part of the combustion surface can form a stable combustion zone, and the stable combustion zone stabilizes the surrounding unstable combustion zone. Can be This makes it possible to stably perform high-load lean combustion in a wide combustion load range, and to suppress the generation of nitrogen oxides.

[Brief description of drawings]

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

2 is a cross-sectional view of the surface combustion burner shown in FIG.

FIG. 3 is a front view of a porous member according to an 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 comparative graph of the stable combustion limit between each example of the present invention and the conventional example.

[Explanation of symbols]

 1-Porous member 5-Mixed gas chamber (central part) 6-Mixed gas chamber (peripheral part) 11-Central part of porous member (high-load lean combustion region) 12-Peripheral member peripheral part (stable combustion region) 13 -Through hole

Claims (4)

[Scope of utility model registration request] 1. A porous member having a large number of pores communicating with the front and back and a mixed gas chamber provided behind the porous member, wherein the mixed gas sent to the mixed gas chamber is porous. In the surface-combustion burner, which passes through the front surface of the member and burns the mixed gas with the front surface as a combustion surface, the porous member is
A large number of through holes having a diameter larger than that of the pores of the porous member are provided so as to be substantially perpendicular to the surface, and the large number of through holes are formed from several kinds of through holes having different diameters. A surface-burning burner characterized by 2. The mixed gas chamber is divided into two chambers, a central portion and a peripheral portion, so that the mixed gas in different states can be separately supplied to the mixed gas chambers. The combustion surface of the front surface of the porous member is divided into a stable combustion region in the peripheral portion and a high-load lean combustion region in the central portion, and the large number of through holes are transparently provided in the high-load lean combustion region in the central portion. The surface combustion burner according to claim 1, wherein 3. The plurality of through-holes provided through the porous member are patterns in which the diameter is changed stepwise from the center of the porous member toward the outer peripheral portion. The surface combustion burner according to claim 1. 4. The plurality of through-holes that are transparently provided in the porous member have a pattern in which a small-diameter through-hole is arranged around a large-diameter through-hole. The surface combustion burner described in 1.