JPH0144898Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention completely prevents backfire,
This invention relates to a flat burner for gas combustion that has good durability and can perform high-temperature combustion for a long period of time.

BACKGROUND ART In recent years, a burning wall as shown in FIGS. 2a and 2b has been known as a combustion device for all kinds of heating furnaces, instead of a burner.

Burning wall is also known as luminous wall, and luminous wall furnace was first developed in America as a gas combustion method.
As shown in Fig. 2 a and b, fuel gas G and combustion air A are mixed, the mixed gas is blown into the breathable refractory 1, and the mixture is combusted within the refractory 1, so that the furnace inner wall surface (bright flame surface) is maintained at the maximum temperature, and the object to be heated in the furnace is heated by radiation heat transfer from the burning wall surface and convection heat transfer of the combustion gas.

Means to solve the invention In this case, the conventional burning wall surface is 1000
If kept at a high temperature of ℃ or higher, the wall heat conduction and the in-wall combustion zone will move to the back, and if left as is, it will reach air mixture chamber 2, causing a backfire, which is a fatal flaw and will damage the device itself. .

Therefore, the practical range of bright flame surface temperature of conventional burning walls remains at around 800 to 1000℃.
It has never been used in high-temperature industrial furnaces of 1200°C or higher.

In the conventional burning wall, as shown in the temperature distribution inside the bright flame wall shown in Figure 3, the temperature difference T at about 10 mm from the bright flame surface (inner surface of the furnace) is as much as 500 to 600°C, which occurs inside the burning wall. This resulted in large internal strains, lowering the structure and strength of the breathable refractory, and resulting in significant shortcomings in durability.

For this reason, the current situation is that the burning wall method is not employed at all in the fields of the steel industry, ceramic industry, and other high-temperature industries.

Means for Solving the Problems It is an object of the present invention to provide a flat burner for gas combustion that solves the above-mentioned drawbacks, completely prevents backup fire, has good durability, and is capable of continuously performing high-temperature combustion for a long period of time.

A specific example of the present invention will be explained based on the drawings.
In FIG. 1, an air mixture chamber 12 is provided on the back surface 16 of the refractory layer 11 through which a large number of thin tubes 13 are embedded and penetrated, and a shielding plate 1 is placed inside the air mixture chamber 12.
Install 4. A recessed portion 34 is provided around the opening of the thin tube 13 on the inner surface 18 of the furnace of the refractory layer 11 . The cross-sectional shape of the concave portion 34 may be circular, oval, quadrangular, polygonal, or the like. There is an advantage that the radiant heat of the flame 35 is easily transmitted to the furnace inner surface 18 of the refractory layer 11.

The fuel gas G supplied to the air mixture chamber 12 of the gas combustion flat burner configured in this way
The dynamic pressure of the mixed gas, which is a mixture of combustion air A and combustion air A, is blocked by the shielding plate 14, suppressed, and uniformly dispersed. Then, the mixed gas detours to the gap between the air mixture chamber 12 and the shielding plate 14, reaches the air mixture chamber 12 on the refractory layer 11 side, is embedded in the refractory layer 11, and penetrates the refractory layer 11. The water is uniformly supplied to a large number of thin tubes 13 in the vicinity. The mixed gas ejected onto the inner surface of the furnace burns in the form of a large number of extremely thin flames 35. Then, the furnace inner surface 18 side of the refractory layer 11 is heated red-hot, and the heat is radiated into the furnace.

The pore diameter of the capillary tube 13 is determined so that the discharge speed of the mixed gas can be maintained (adjusted) higher than the combustion propagation speed of the mixed gas. At this time, the mixed gas is uniformly supplied to the thin tube 13, making it easy to determine the hole diameter.

Even if the temperature on the furnace inner surface 17 side of the capillary tube 13 and the furnace inner surface 18 side of the refractory layer 11 becomes higher than the ignition temperature of the mixed gas, the back surface 15 side of the capillary tube 13 and the back surface 16 side of the refractory layer 11 will not reach the mixed gas. There is no risk of backfire as the water is cooled down. Furthermore, the gap between the inner peripheral surface of the air mixture chamber 12 and the shielding plate 14 is
It is made smaller than the cross-sectional area of the introduction pipe 19 that introduces the mixed gas into the mixed gas chamber 12 to further improve safety against backup fire.

The hole diameter of the thin tube 13 is preferably 1 to 10 mm; if it is less than 1 mm, the combustion power will be too small; if it exceeds 10 mm, it will be the same as a conventional single tube burner, but the risk of backfire will increase, and the back pressure of the mixed gas supply will be kept high. Therefore, the supply amount is limited to large quantities.

The cross-sectional shape of the thin tube 13 is circular, oval, square,
It can be any polygonal shape, but it is generally circular,
Use metal (SUS, heat-resistant metal, etc.) or ceramic (Si ₃ N ₄ , SiC, Al ₂ O _3, etc.). The refractory layer 11 is made of an Al ₂ O ₃ -SiO ₂ based refractory product or refractory brick, an insulating castable, an insulating brick, a ceramic fiber sheet, or an Si ₃ N ₄ refractory or SiC based refractory that has good radiation when red-hot. Refractories can be used. For this reason, the refractory layer 11 made of breakable materials or refractory bricks has a denser structure and higher strength than the breathable refractories used for burning walls, and can withstand rapid heating and cooling temperature cycles. is good. Ceramic fiber sheets also suddenly heat up.
Good durability against cooling temperature cycles.

An example of the arrangement of the refractory layer 11 is as follows; an Al ₂ O ₃ -SiO ₂ castable or refractory brick 22 is placed on the furnace inner surface 18 side, and a heat insulating castable, heat insulating brick or ceramic fiber sheet 23 is placed on the back side 16.

Si ₃ N ₄ refractory or SiC refractory on the inner surface 18 side of the furnace, insulation castable, insulation brick or ceramic fiber sheet 2 on the back side 16
3.

Next, a specific example of the present invention will be shown.

Flat burner specifications for gas combustion Combustion gas: LPG (combustion propagation velocity (temperature 50℃)
0.55m/sec) Supply amount: LPG 3Nm ³ /H, Air 73.5Nm ³ /H back pressure
360mmAq Plane burner area: 400mm x 400mm = 0.16m ² Refractory layer thickness: Al ₂ O ₃ −SiO ₂ castable 50
mm, insulation castable 20mm Number of capillary tubes: 360 Tube material: SUS Capillary dimensions: Inner diameter 2mmφ Gas flow velocity in capillaries: 14.7 m/sec Shielding plate dimensions: 396mm x 396mm Shielding plate material: SS 41 Furnace inner surface temperature: 1300℃ (recess dimension Diameter 5mmφ, depth 5mm) Back temperature: 41℃ Mixed gas supply amount 60Nm ³ /N ~ under the above conditions
Stable high-temperature combustion was achieved in the range of 240Nm ³ /N.

Effects of the invention According to the invention as described above, there are the following effects.

(1) Backfire can be completely prevented, durability is good, and high-temperature combustion can be carried out continuously for a long period of time.

(2) If the refractory layer is made by pouring castable refractories, large-sized ones can be made.

(3) The required heating conditions can be easily designed by changing the size of the tubes and the density of the distribution.

(4) Si ₃ N ₄ refractory bricks with good radioactivity or
SiC-based refractory bricks can be used, increasing efficiency and saving energy.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view showing an embodiment of the gas combustion flat burner of the present invention, and FIG. 2 is a schematic cross-sectional view of a conventional burning wall, where a is a general type and b is a modified type. FIG. 3 is a graph showing the temperature distribution within the luminous flame wall of a burning wall with a conventional structure. In the figure, 11... refractory layer, 12... air mixture chamber, 13... thin tube, 14... shielding plate, 16...
...Refractory layer back, 18...Furnace inner surface, 22...Castable or refractory brick, 23...Insulating material, 3
4...Concave portion.

Claims (1)

[Scope of utility model registration request] An air mixture chamber 12 is provided on the back surface 16 of the refractory layer 11 in which a large number of thin tubes 13 are embedded and penetrated, and a concave portion 34 is formed around the opening of the thin tubes 13 on the inner surface 18 of the furnace. shielding plate 1
4 is attached, and the refractory layer 11 has a castable or refractory brick 22 on the inner surface 18 side of the furnace, and a heat insulating material 23 on the rear surface 16 side.