JP2001021118A - LOW NOx RADIANT TUBE BURNER - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low NOx radiant tube burner with a very simple structure and inexpensiveness by structuring a primary combustion chamber and a secondary air flowing route by inserting a fireproof dividing board inside the radiant tube burner. SOLUTION: A fireproof dividing board 6 is inserted inside a radiant tube 1 on the front of a fuel supplying part 5 for a burner and a combustion air supplying part 4. A first space and a second space are divided and structured by the fireproof dividing board 6, the first space 7 comprises a first combustion chamber by being arranged so that fuel from the fuel supplying part 5 is supplied to the first space 7 and the second space 8 comprises a secondary air flowing route.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low NOx radiant tube burner.

[0002]

2. Description of the Related Art A radiant tube burner is provided at the end of a thin tube having a diameter of about 3 to 8 inches, which burns in the tube and heats an object to be heated by heat radiation from the outer surface of the tube. is called. One of the burner's low NOx methods is a multi-stage combustion method in which air is supplied stepwise. FIG. 9 shows an example of the structure of a burner that is currently in practical use as a result of applying this method. As shown in the figure, this burner has a cylindrical primary combustion chamber b disposed coaxially with a radiant tube a, in which fuel and primary air are mixed to perform primary combustion. Thereafter, secondary air flowing outside the primary combustion chamber reacts with combustion products in the primary combustion chamber to perform secondary combustion.

[0003] In the above-described burner, as a method of holding the cylindrical primary combustion chamber coaxially at the center of the radiant tube, the following method is used. a. As shown in FIG. 9, the primary combustion chamber is
Or a method of being fixedly integrated with the burner body d and supported by a cantilever b. The primary combustion chamber is configured separately from the fuel supply section and the like, and the primary combustion chamber is supported by providing a protruding support e as shown in FIG. 10 or a semi-circular support as shown in FIG. Method of providing and supporting a large support f such as a piece c. A method combining the above a and b, in which the primary combustion chamber is fixedly integrated with the fuel supply unit or the burner main body and supported by a cantilever, and a support such as a protrusion is provided at the tip end side.

On the other hand, in the above-described burners, the primary combustion chamber is exposed to high temperatures, and it is an issue how to suppress the influence. At high temperatures, metals are thermally deformed. Ceramic or the like is used.

[0005]

However, each of the above-mentioned conventional techniques has the following disadvantages. (1) First, according to the method a, it is difficult to fix the metal fuel supply unit and the burner main body to the ceramic primary combustion chamber, and the structure becomes complicated. Also, the burner length becomes longer,
And since it is necessary to insert the primary combustion part fixed to the burner into the radiant tube, it is difficult to attach and remove the burner to the radiant tube,
In this case, the ceramic primary combustion chamber may be damaged by some mechanical impact. (2) In the method (b), when the support area of the projection-shaped support is small, the damage is easily caused, and the damage causes misalignment. On the other hand, when the support area is increased by increasing the support, the flow of the secondary air is affected by the support, and the surface temperature distribution of the radiant tube deteriorates. (3) In the method c, both disadvantages (1) and (2) occur. Further, the following disadvantages are common to the conventional methods. (4) If you create a complex part with ceramic,
This leads to higher costs. (5) Primary / secondary air volume (primary / secondary air passage area)
Is difficult to change. In particular, the sectional area of the primary combustion chamber cannot be changed unless parts are replaced, and fine adjustment of combustion cannot be performed unless spare parts are prepared. An object of the present invention is to solve such a problem.

[0006]

According to the present invention, a refractory partition is inserted into a radiant tube in front of a fuel supply section and a combustion air supply section of a burner. First and second spaces are defined by plates, and the first space is arranged to supply fuel from a fuel supply unit to the first space to form a primary combustion chamber. Low NOx configured as air flow path
We propose a radiant tube burner.

According to the present invention, a tubular body made of a refractory heat insulating material is provided on the inner wall of a radiant tube in front of a fuel supply section and a combustion air supply section of a burner, and a refractory partition plate is inserted into the tubular body. The first, which is divided by a refractory partition
A second space is formed, and the first space is arranged so as to supply the fuel from the fuel supply unit to form a primary combustion chamber, and the second space is formed as a secondary air flow path.
We propose an Ox radiant tube burner.

According to the present invention, a refractory partition is inserted into a radiant tube in front of a fuel supply section and a combustion air supply section of a burner, and first and second spaces defined by the refractory partition are formed. The first space is configured to supply the fuel from the fuel supply unit to the first space and configured as a primary combustion chamber, and the second space is configured as a secondary air flow path,
We propose a low NOx radiant tube burner in which a notched tubular body of refractory heat insulating material is installed on the inner wall of the radiant tube on the primary combustion chamber side.

According to the present invention, in each of the above-described configurations, it is proposed that the refractory partition plate be provided with a communication hole communicating the first and second spaces defined by the refractory partition plate.

According to the present invention, since the primary combustion chamber and the secondary air flow path are formed by inserting the refractory partition plate into the radiant tube, a very simple and inexpensive burner can be provided.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings. 1A and 1B show a radiant tube burner according to a first embodiment of the present invention, wherein FIG. 1A is a longitudinal sectional view, and FIG. 1B is a sectional view taken along line A-AA of FIG. In FIG. 1, reference numeral 1 denotes a radiant tube, 2 denotes a furnace wall made of a heat insulating material or the like, and the right side of the furnace wall 2 in the drawing is a heating chamber in the furnace.
The left side is the outside of the furnace. Reference numeral 3 indicates a portion of the radiant tube 1 corresponding to the inside of the furnace wall. At the end of the radiant tube 1 located outside the furnace, a combustion air supply pipe 4 and a fuel gas supply pipe 5 are provided. In the present invention, a space inside the radiant tube 1 is defined by inserting a refractory partition plate 6 made of fine ceramic or the like into the corresponding portion 3 in the furnace wall of the radiant tube 1,
The first space 7 on the upper side of the refractory partition plate 6 and the second space 8 on the lower side are configured. The width W of the refractory partition plate 6 is configured to be smaller than the inner diameter of the radiant tube 1, so that the upper first space 7 is configured to be larger than the lower second space 8. As shown in FIG.
Is configured to eject fuel gas toward the axial center of the radiant tube 1, and the refractory partition plate 6 is located below the fuel gas supply pipe 5. The first space 7 is provided above the first space 7.

In the above configuration, the combustion air is supplied from the combustion air supply pipe 4 to both the first space 7 and the second space 8, and the fuel gas is supplied from the fuel gas supply pipe 5 to the first space. 7 is supplied. Therefore, in the first space 7, the fuel gas and the combustion air are mixed to perform the primary combustion, while a part of the combustion air flows through the second space 8 and flows out from the downstream end to the first space 7. And is mixed with the combustion products in the space 7 and is subjected to secondary combustion. From this, the first space 7
Functions as a primary combustion chamber, and the second space 8 functions as a secondary air flow path to perform two-stage combustion. This operation corresponds to the case where the communication hole 9 shown in FIG. 1 is not provided, and if the communication hole 9 is provided at an appropriate position of the refractory partition plate 6, the second space 8 A portion of the combustion air flowing through the first space 7 flows through the communication hole 9 into the first space 7 and is provided for combustion. Therefore, three or more stages of combustion air including the combustion air flowing out from the downstream end portion are included. Multi-stage combustion can be performed.

The ratio of the cross-sectional area of the first space 7 as the primary combustion chamber to the cross-sectional area of the second space 8 as the secondary air flow path is determined by the width of the refractory partition plate 6 as shown in FIG. Can be changed and adjusted. That is, in FIG. 2, the value of the above ratio can be increased by narrowing the width W of the upper refractory partition plate 6 to a width W ′ (W> W ′). That is, when changing the size of the primary combustion chamber to a direction in which the size of the primary combustion chamber is enlarged, the width W is changed to W ′ by removing the refractory partition plate 6 and shaving the edge.
And then reinsert it into the radiant tube 1. Of course, if the refractory partition plate 6 is prepared and replaced, the size of the primary combustion chamber can be reduced.

Since the refractory partition plate 6 is inserted into the radiant tube 1 to divide a space, its shape is appropriate. For example, the refractory partition plate 6b shown in FIG. 3 has a circular arc cross section. The width of the refractory partition plate 6b is configured to be slightly smaller than the inner diameter of the radiant tube 1, and is inserted so that the upper side is concave. In this case, as in FIG.
A large first space 7 is formed above the refractory partition plate 6a, and a small second space 8 is formed below the refractory partition plate 6a. Next, FIG. 4 shows a refractory partition plate 6a having an arc cross section similar to that of FIG. In this case, contrary to FIG. 3, a large first space 7 is formed below the refractory partition plate 6a, and a small second space 8 is formed above the refractory partition plate 6a. Next, the refractory partition plate 6b shown in FIG. 5 has an angled cross section. In this case, as in FIG. 4, a first space 7 is formed below the refractory partition plate 6a, and a second space 8 is formed above the refractory partition plate 6a. It is configured. Next, a refractory partition plate 6c shown in FIG. 6 is configured such that a convex piece is integrally formed on the lower side of the flat plate of FIG. 1 to form a T-shaped cross section.
Similarly, a large first space 7 is formed above the refractory partition plate 6c, and a small second space 8 is formed below the refractory partition plate 6c. As for the refractory partition plates 6a, 6b, 6c of the above-mentioned respective shapes, the first space 7 as the primary combustion chamber and the second space as the secondary air flow path are formed by adjusting the width as described with reference to FIG. The ratio of the space 8 can be adjusted.

Next, FIG. 7 shows a second embodiment of the radiant tube burner of the present invention, in which (a) is a longitudinal sectional view, and (b) is a sectional view taken along the line B-BB of (a). is there. In this embodiment, a tubular body 10 made of a refractory and heat-insulating material is inserted into the corresponding portion 3 in the furnace wall of the radiant tube 1, and a refractory partition plate 6 is inserted into the tubular body 10 as in the first embodiment. The space inside the radiant tube 1 is thereby partitioned, and the first space 7 above the refractory partition plate 6 and the second space 8 below the refractory partition plate 6.
And is composed. Also in this configuration, the first space 7 functions as a primary combustion chamber, and the second space 8 functions as a secondary air flow path.
Therefore, the same components are denoted by the same reference numerals, and redundant description will be omitted. In the second embodiment, since the tubular body 10 made of the refractory heat insulating material is installed inside the corresponding portion 3 inside the furnace wall of the radiant tube 1, the inside of the furnace wall of the radiant tube 1 due to the heat generated in the primary combustion. Overheating of the corresponding part 3 can be prevented. Since the tubular body 10 made of the refractory heat insulating material prevents overheating of the corresponding portion 3 in the furnace wall of the radiant tube 1 due to the primary combustion in this manner, the tubular body 10 on the side of the second space 8 functioning as a secondary air flow path. It is not always necessary for the inner wall of the radiant tube 1. Therefore, in the embodiment shown in FIG. 8, a refractory partition plate 6 is provided on the corresponding portion 3 in the furnace wall of the radiant tube 1.
Is inserted to form a space inside the radiant tube 1 to form a first space 7 on the upper side of the refractory partition plate 6 and a second space 8 on the lower side, and the first space 7 is a primary combustion chamber. The second space 8 is arranged so as to function as a secondary air flow path while functioning as a chamber, and a cut-out cylindrical body 11 made of a fire-resistant heat insulating material is installed on the inner wall of the radiant tube 1 on the first space 7 side. is there. In this configuration, the second space 8 functioning as a secondary air flow path is not transferred to the inner wall of the radiant tube 1 due to the cooling effect of the combustion air flowing therethrough, so that overheating is prevented.

[0016]

As described above, the present invention has the following effects. a. Since the primary combustion chamber and the secondary air flow path are configured by inserting a refractory partition plate into the radiant tube, a very simple and inexpensive low-NOx radiant tube burner can be provided. b. By changing the shape and width of the refractory partition, the amount of primary / secondary air (cross-sectional area of the primary combustion chamber / cross-sectional area of the secondary air passage) can be easily changed. It is possible. c. In particular, changes to the direction to increase the size of the primary combustion chamber can be easily changed by reducing the width of the refractory partition, and there is no need to procure refractory partition of different width as additional parts. In addition, it is unnecessary to prepare spare parts and the like.

[Brief description of the drawings]

FIG. 1 shows a radiant tube burner according to a first embodiment of the present invention, in which (a) is a longitudinal sectional view and (b) is a sectional view taken along line A-AA of (a).

FIG. 2 is an explanatory view of a section taken along the line A-AA in FIG. 1 (a) for explaining an operation of changing the size of the primary combustion chamber in a direction to increase the size.

FIG. 3 shows another embodiment of a refractory partition plate.
It is sectional drawing of the location similar to the A-AA line sectional location of (a).

FIG. 4 shows still another embodiment of the refractory partition plate.
It is sectional drawing of the location similar to the A-AA line sectional location of (a).

FIG. 5 shows still another embodiment of the refractory partition plate.
It is sectional drawing of the location similar to the A-AA line sectional location of (a).

FIG. 6 shows still another embodiment of the refractory partition plate.
It is sectional drawing of the location similar to the A-AA line sectional location of (a).

FIGS. 7A and 7B show a radiant tube burner according to a second embodiment of the present invention, wherein FIG. 7A is a longitudinal sectional view, and FIG. 7B is a sectional view taken along line B-BB of FIG.

8 shows another embodiment of the shape of the refractory heat insulating material, and is a cross-sectional view similar to the cross-section taken along the line B-BB of FIG. 7 (a).

9 shows an example of a conventional radiant tube burner that performs two-stage combustion, where (a) is a longitudinal sectional view and (b) is a sectional view taken along line C-CC of (a).

FIGS. 10A and 10B show an example of a method of coaxially supporting a primary combustion chamber in a radiant tube. FIG. 10A is a longitudinal sectional view, and FIG. 10B is a sectional view taken along line D-DD of FIG.

11A and 11B show another example of a method of coaxially supporting a primary combustion chamber in a radiant tube, wherein FIG. 11A is a longitudinal sectional view, and FIG. 11B is a sectional view taken along line E-EE of FIG. .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Radiant tube 2 Furnace wall 3 Correspondence in furnace wall 4 Combustion air supply pipe 5 Fuel gas supply pipe 6 Fireproof partition (flat plate) 6a Fireproof partition (arc section) 6b Fireproof partition (angle cross section) 6c Fireproof partition (T-shaped cross section) 7 First space (Primary combustion chamber) 8 Second space (Secondary air flow path) 9 Communication hole 10 Fireproof heat-insulating material cylinder 11 Fireproof heat-insulating material notched cylinder

Claims (4)

[Claims] 1. A fireproof partition plate is inserted into a radiant tube in front of a fuel supply section and a combustion air supply section of a burner to form first and second spaces defined by the fireproof partition plate. A low NOx radiant tube burner, wherein a first space is configured to supply fuel from a fuel supply unit to a first space, and the second space is configured as a secondary air flow path. 2. A fireproof heat insulating material cylinder is installed on an inner wall of a radiant tube in front of a fuel supply unit and a combustion air supply unit of a burner, and a fireproof partition plate is inserted into the cylinder.
First and second spaces are defined by the refractory partition plate, and are arranged so as to supply fuel from the fuel supply unit to the first space to constitute a primary combustion chamber. NOx radiant tube burner characterized by having a secondary air flow path 3. A refractory partition is inserted into a radiant tube in front of a fuel supply section and a combustion air supply section of a burner to form first and second spaces defined by the refractory partition. The first space is configured to supply the fuel from the fuel supply unit to the first space and configured as a primary combustion chamber, and the second space is configured as a secondary air flow path, and an inner wall of a radiant tube on the side of the primary combustion chamber is formed. Low NOx radiant tube burner characterized by having a notched tubular body made of fire-resistant insulation material 4. The refractory partition plate according to claim 1, further comprising a communication hole communicating with the first and second spaces defined by the refractory partition plate. Low NOx radiant tube burner described