JPH0676841B2 - Surface burning burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a surface combustion burner having a two-layer structure formed by joining a combustion resistant material layer and a metal fiber mat layer, and particularly a joining method between both layers. Regarding

[Prior art] Infrared heating device, which is expected to be applied in a wide range of fields such as food cooking, heating, and drying of coated materials, and surface combustion as one of the technologies that uses inexpensive and high-calorie gas fuel as its heat source. There is a burner.

The surface combustion burner efficiently converts the thermal energy of the combustion gas, which is largely carried away by convection in normal combustion, into radiant heat. Air is burned from one side of a permeable plate (hereinafter referred to as burner plate) with air. By supplying a premixed gas fuel and burning it in the surface layer portion on the other side, the surface layer portion itself of the burner plate is heated to cause it to release radiant heat. Therefore, in the surface combustion burner, gas combustion is maintained with the flame closely adhering to the surface of the burner plate or entering the surface layer, and radiant heat is radiated from the flame and the surface layer of the burner plate heated to the red heat state. It

In surface combustion burners, those that use a metal sintered plate or a ceramic sintered plate as the material of the burner plate have already been put to practical use in several fields such as cooking utensils, and metal and ceramic fibers are layered. Those using a sintered fiber mat are also actively studied. These surface-burning burners have the advantage of being able to obtain radiant heat with high efficiency and being capable of stable combustion independent of the external environment such as wind and temperature. The burner plate made of mat (hereinafter referred to as SUS mat) is capable of complexly shaping the surface shape, has good strength, and if a material with high porosity is selected, it has a large area, low pressure loss, high burnup, and high burnup. Since it is possible to easily produce a product having a high output density and is relatively inexpensive, it is expected to be applied to, for example, a heating device in an outdoor work site and baking and drying of automobile coating.

FIG. 3 is a schematic diagram showing an example of a surface combustion burner using a burner plate made of SUS mat, an infrared heater used in an outdoor work site, and a portion including the burner plate is shown in a cross section.

In FIG. 3, the burner plate m is composed of SUS316 long fibers having a diameter of 20 μm and a length of about 50 mm, which are formed into a mat-like shape and then sintered together to form a SUS mat having a thickness of 5 mm. The surface layer portion m1 serves as a gas combustion region and a radiant heat release portion.

Here, the burner body K to which the burner plate m is attached is connected to a gas nozzle GN, a solenoid valve SV, a gas supply system including a cylinder T of fuel gas, and an air supply system including a blower F. Further, a spark electrode S for ignition is provided so as to face the lower end of the burner plate m, and the control device C operates the switch to operate the solenoid valve SV and the blower F, and at the same time as the spark electrode S. A spike-like high voltage is applied between the burner plates m to ignite the gas-air mixture on the surface of the burner plates m. The above-mentioned respective constituent members are fixed in positional relation to each other on a movable base B provided with wheels.

Now, when the switch of the control device C is operated to activate this heating device, the solenoid valve SV is opened to inject and supply the fuel gas from the nozzle GN, and at the same time the blower F is activated to supply the air and the burner. In the main body K, the fuel gas and the air are in a mixed state, flow in the direction of the burner plate m, pass through the burner plate m, and leak out from the surface layer portion m1. On the other hand, a spark is generated between the spark electrode S to which a high voltage is applied and the burner plate m, the air-gas mixture leached in this part is ignited, and the flame is quickly burned on the surface of the burner plate m. Propagate to the whole and combustion operation is started.

Here, in order for this surface combustion burner to perform efficient combustion, it is necessary to strictly control the gas supply amount and the air supply amount. That is, the ratio of the gas supply amount and the air supply amount (mixing ratio) is made substantially equivalent to the stoichiometric ratio of the chemical reaction, and the flow rate of the gas-air mixture passing through the burner plate m is such that the flame leaves the surface of the burner plate m. It is set in the range not to do. As a result, in the surface layer portion m1 of the burner plate m, stable combustion is continued to become a red heat state, and radiant heat in an amount substantially dependent on the temperature of the surface layer portion m1 is radiated.

[Problems to be Solved by the Invention] In a surface combustion burner using a burner plate made of SUS mat, oxidative deterioration of the surface layer of the burner plate, which is in a red heat state, progresses remarkably, and the SUS mat rapidly becomes thin and collapses. The life of the burner plate is short. For example, the life of the burner plate m of the conventional heater does not exceed 100 hours even in normal operation.

FIG. 4 shows a temperature distribution in the thickness direction of the burner plate m when the conventional surface combustion burner is operated normally.

In FIG. 4, the temperature in the surface layer portion m1 of the burner plate m reaches 1200 ° C., which is a severe environment for a SUS mat which should adopt a normal temperature of 800 ° C. or lower. On the other hand, since the SUS mat itself is a material with low thermal conductivity and is constantly cooled by the unburned gas-air mixture passing through it, the temperature drops sharply when it is separated from the surface layer part m1, and within 1 mm it is 800 The temperature is below ℃, which is the temperature that the SUS mat can withstand.

Paying attention to this point, the surface layer portion m1 of the burner plate m is replaced with a combustion resistant material, for example, a mat made of sintered Al ₂ O ₃ fibers. That is, an attempt was made to bond a SUS mat and a heat-resistant material mat into a burner plate having a two-layer structure. But SU
Since the S-fiber and the heat-resistant material fiber have considerably different sintering temperatures, it is difficult to bond the mats by sintering. Attempts have also been made to connect the two layers using heat-resistant screws and nuts, and to join them by using heat-resistant wire rods. However, the holes that penetrate them and the heat-resistant members ensure uniform combustion on the combustion surface. Since the property is lost and the SUS mat deteriorates along the holes and the heat-resistant member, the desired life extension effect of the burner plate cannot be obtained.

An object of the present invention is to provide a surface combustion burner which has a strong bond between the SUS mat layer and the heat-resistant material layer and has a long life in which combustion uniformity on the combustion surface is secured.

[Means for Solving the Problem] A surface combustion burner according to claim (1) of the present invention forms a gas combustion zone, and a first layer made of a mat or cloth made of a flame resistant material, and the first layer. In a surface combustion burner having a surface 2 layer made of a metal fiber mat for supplying gas to the first layer and supporting the first layer, a third layer which is sewn and joined to the first layer and combustion joined to the second layer. Are arranged between the first layer and the second layer.

A surface combustion burner according to claim (2) of the present invention is the surface combustion burner according to claim (1), in which a ceramic cloth is used as the first layer.

[Operation] In the surface combustion burner according to claim (1) of the present invention, premixed air and gas are supplied from the second layer side,
This mixture passes through the second layer, leaches into the first layer, burns in the surface layer portion of the first layer, and heats the surface layer portion into a red hot state. Here, the first layer is made of a flame resistant material such as a ceramic fiber mat, and the second layer is made of
A SUS mat is generally used in consideration of strength and economy.

On the other hand, the first layer and the second layer are sewn and joined to the first layer,
It is firmly joined to the second layer through the third layer which is combustion-bonded. That is, the third layer is made of a material that is easy to sinter with the second layer, for example, the same material. After the first layer and the third layer are sewn and joined, this is sinter-bonded to the second layer, or the third layer. The second layer material is stacked on the layer and sintered to form a mat.

As a result, the second layer and the third layer do not have to be directly exposed to high temperatures due to gas combustion. Further, since there is no hole penetrating the burner plate or a heat resistant member, the air-gas mixture flow rate on the combustion surface and the uniformity of the combustion state are maintained.

Here, in the first layer, various heat resistant materials, that is, ceramic fiber mats and refractory metal fiber mats,
Or woven cloth or pile cloth using the same material is adopted, but the materials of the first layer, the second layer, and the third layer have the same porosity, or It is desirable that steps and sudden changes do not occur. The thread used for suturing is made of a material having combustion resistance, for example, twisted thread of a heat-resistant metal such as Kanthal or a ceramic fiber material, or a single wire material, but a thin thread is preferable from the viewpoint of making the combustion state uniform.

In the surface-combustion burner according to claim (2) of the present invention, the first layer is a ceramic cloth which is easier to handle than ceramic fiber mats and which is less likely to be crushed or collapsed by stitching. The first layer and the third layer can be easily joined by using a sewing machine or the like.

Embodiments of the Invention Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a structure of a burner plate portion of a surface combustion burner according to an embodiment of the present invention, (a) is a front view of the burner plate M,
(B) is sectional drawing which expanded the one part and looked at from the side surface. The surface-combustion burner of this example is the same as the conventional example of the surface-combustion burner, which has a single-layer burner plate m of SUS mat. The first layer is Al ₂ O ₃ cloth 1, and the second and third layers are SUS mat 2 respectively. 3 is a burner plate M having a three-layer structure.

In FIGS. 1 (a) and 1 (b), the Al ₂ O ₃ cloth 1 of the first layer is a non-woven fabric composed of Al ₂ O ₃ long fibers having a diameter of 8 μm and having a thickness of 1 to 2 mm. The three layers of SUS mats 2 and 3 are
SUS316 filaments with a diameter of 20 μm and a length of 50 mm are formed into a mat and sintered together, and each has a thickness of 4 m.
m and 0.5 mm. The porosities of the Al ₂ O ₃ cloth 1 and the SUS mats 2 and ₃ are almost equal and are 90% or more.

This burner plate M is made by stacking an Al ₂ O ₃ cloth 1 having a thickness of 1 to ₂ mm and a SUS mat 3 having a length of 0.5 mm and using a solid wire of Kanthal, which is an alloy of iron, chromium or the like, and an industrial sewing machine. After sewn vertically and horizontally according to a grid-like stitch pattern of about 10 mm square, a 4 mm-thick SUS mat 2 is superposed on the SUS mat 3 and pressed and burned at a high temperature.

FIG. 2 shows the gas mixture ratio of the gas-air mixture (ratio between the actual air supply amount and the stoichiometric ratio equivalent amount) and the interface temperature of each layer of the burner plate M in the surface combustion burner of this example. It is a diagram showing a relationship. Here, the flow velocity of the mixture is 15 cm / sec, and methane CH ₄ is selected as the gas fuel.

As shown in the diagram of Figure 2, the burner plate M by replacing the portion of the gas combustion becomes high red heat in progress on a Al ₂ O ₃ cross, Al ₂ O ₃ with respect to various gas mixing ratio Cross and SUS
800 ℃ or less at the interface of mat 3 and at the interface of SUS mats 2 and 3
The operation will be kept below 600 ° C.

Therefore, the progress of oxidation of SUS mats 2 and 3 is delayed,
The burner plate life, which was about 00 hours, reached 5000 hours even under the maximum load operation, and was found in the burner plate with a two-layer structure in which Al ₂ O ₃ cloth 1 and SUS mat 2 were simply sewn together. No flame was emitted on the stitch pattern on the burning surface during operation, and the uniformity of combustion was improved.

In this embodiment, the SUS mat and the Al ₂ O ₃ cloth are sewn together with the Kanthal wire, but these materials can be selected and combined in various ways in consideration of heat resistance and economy. For example Al
Applications such as replacing ₂ O ₃ cloth with TiO ₂ cloth and replacing Kanthal wire with platinum wire are possible.

EFFECTS OF THE INVENTION In the surface combustion burner according to claim (1) of the present invention, the burner plate surface layer, which is the gas combustion region, is composed of the first layer of the combustion resistant material, so that the burner plate is oxidized and deteriorated. Progress is slow. In addition, the first layer is the second layer through the sewn third layer.
Since the burner plate and the surface combustion burner are easy to manufacture and handle because they are sintered and joined to the layers, combustion unevenness of the combustion surface due to stitching and partial burner plate Oxidative deterioration phenomenon is less likely to occur.
Therefore, the life of the burner plate is extended, the operating rate can be improved, and the operating cost can be reduced.

In addition, since the first and third layers are sewn together, it is possible to freely select materials without considering the difference in sintering temperature or the matching of materials such as affinity as in the case of sintering. is there.

In the surface-combustion burner according to claim (2) of the present invention, since a ceramic cloth that is much easier to handle and cheaper than a mat having a sintered structure is used, the stitching work can be performed easily and efficiently. .

[Brief description of drawings]

FIG. 1 shows a structure of a surface combustion burner according to an embodiment of the present invention, (a) is a plan view and (b) is a partial sectional view. FIG. 2 is a diagram showing the relationship between the operating conditions of the surface combustion burner according to the embodiment of the present invention and the interfacial temperature of each layer of the burner plate. FIG. 3 is for explaining a conventional surface combustion burner, and is a schematic diagram showing the structure of a heating device for outdoor work. FIG. 4 is a diagram showing a temperature distribution in a cross section of a SUS mat of a conventional surface combustion burner. [Explanation of symbols of main parts] 1 ... Al ₂ O ₃ cloth, 2, 3 ... SUS mat, 4 ... Kanthal wire

Claims (2)

[Claims] 1. A first layer comprising a mat or cloth made of a combustion resistant material, which forms a gas combustion zone, and a metal fiber mat which supplies gas to the first layer and supports the first layer. In a surface combustion burner having a second layer, a third layer that is sewn and joined to the first layer and is combustion-bonded to the second layer is arranged between the first layer and the second layer. And a surface burning burner. 2. The surface combustion burner according to claim 1, wherein ceramic cloth is used as the first layer.