JP2002349807A - Single end type radiant tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that since an inner tube is formed in a straight pipe including an opening part with an equal diameter in the direction of its length, combustion exhaust gas does not flow out from distribution holes and substantially flows out from the opening part at an end part so that the end side of an outer tube is partially heated to produce a high temperature range and the uniform temperature distribution of the outer tube cannot be obtained in a conventional single end type radiant tube device in which the inner tube is concentrically disposed in the outer tube with an end closed, the inner tube has the end opened and the distribution holes provided on an outer periphery and an exhaust part is provided in the rear end side of the outer tube and a burner part is provided in the rear end side of the inner tube. SOLUTION: In the single end type radiant tube device, a passage throttle means for throttling a passage is provided in the downstream side of the distribution holes 3 in the inner tube 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-end type radiant tube apparatus which is often used for performing various types of heat treatment in a furnace.

[0002]

2. Description of the Related Art A single-end type radiant tube device includes: a. Can indirectly heat the processed material,
b. High combustion efficiency, c. It is often used for performing various atmospheric heat treatments in a furnace because it can be easily attached to a furnace.

FIGS. 4 and 5 show a conventional example of a single-ended radiant tube device. FIG. 4 is an overall explanatory diagram, and FIG. 5 is an enlarged explanatory diagram showing only the distal end side. This single-end type radiant tube device a has an inner tube c concentrically installed inside an outer tube b having a closed end,
The inner pipe c has an opening at the front end and a dispersion hole d provided as necessary, and an exhaust portion e at the rear end side of the outer tube b and a burner portion f at the rear end side of the inner pipe c. The rear end of the outer tube b is attached to and supported by the furnace wall g. Reference numeral h denotes an air introduction part, reference numeral i denotes a fuel gas supply pipe provided concentrically in an inner pipe c, and j denotes a flame holding part.

In the above configuration, the high-temperature combustion exhaust gas generated by burning in the inner tube c in the burner portion f flows in the inner tube c toward the distal end side, and the outer tube b extends from the opening k at the distal end.
And then flows through the gap between the outer tube b and the inner tube c in the rear end direction to heat the outer tube b and indirectly heat the processed material in the furnace. e through a flue (not shown). At this time, a part of the combustion exhaust gas in the inner pipe c flows through the dispersion hole d into the gap between the inner pipe c and the outer pipe b.

[0005] In general, when performing various heat treatments, it is important that the temperature of the processed material be uniform. Therefore, even in the single-end type radiant tube device, as the performance thereof, it is required that the temperature distribution of the outer tube is more uniform.

Therefore, in the above-described conventional example, a dispersion hole is provided in the inner tube, and a portion of the combustion exhaust gas in the inner tube is caused to flow out through the dispersion hole into a gap between the inner tube and the outer tube. And the temperature distribution of the outer tube is made uniform.

[0007]

However, in the conventional single-end type radiant tube device, the inner tube has a straight tube shape including the opening and having the same diameter in the length direction. Few. For this reason, the amount of combustion exhaust gas proportional to the area does not always flow out through the dispersion hole (indicated by a broken arrow in FIG. 5), and most of the combustion exhaust gas does not flow out of the dispersion hole but flows out of the tip. It may flow out of the opening.

For this reason, the distal end side of the outer tube near the opening of the inner tube is locally heated to generate a high temperature range as shown in FIG. 5, and a uniform temperature distribution of the outer tube cannot be obtained.
Therefore, an object of the present invention is to solve such a problem.

[0009]

In order to solve the above-mentioned problems, according to the present invention, an inner tube is provided concentrically inside an outer tube having a closed end, and the inner tube has an opening at the end and an outer periphery. In a single-end type radiant tube device having a configuration in which a dispersion hole is provided, an exhaust portion on the rear end side of the outer tube, and a burner portion on the rear end side of the inner tube, the inner tube is downstream of the dispersion hole. In addition, a flow path restricting means for restricting the flow path is constituted.

In the above construction, in the present invention, the flow path restricting means can be formed by narrowing the tip of the inner pipe. At this time, the flow path restricting means is formed by tapering the tip of the inner pipe. can do.

Further, in the present invention, the flow path restricting means may be constituted by providing a restrictor plate having a hole upstream of the tip of the inner pipe and downstream of the dispersion hole.

In the present invention, as an example, it is preferable that the cross-sectional area of the flow channel portion narrowed by the flow channel throttle means is set to 15 to 30% of the cross-sectional area of the flow channel portion which is not narrowed.

According to the present invention, since the inner pipe narrows the flow path downstream of the dispersion hole by the flow path narrowing means, the pressure loss on the upstream side of the narrowed flow path portion increases. .
For this reason, a part of the high-temperature combustion exhaust gas in the inner pipe on the upstream side of the flow path can be reliably discharged to the gap between the inner pipe and the outer pipe through the dispersion hole due to the internal pressure.

In this manner, local heating of the distal end side of the outer tube can be prevented, and the temperature distribution of the outer tube can be made uniform.

The flow path restricting means may be formed at the tip of the inner tube, or may be formed at an appropriate position on the downstream side of the dispersion hole.

The distribution of the amount of the combustion exhaust gas flowing out from the opening of the inner pipe and the amount of the combustion exhaust gas flowing out of the dispersion hole is determined by taking into account the arrangement of the dispersion holes and the sectional area thereof, and the like. The temperature distribution in the direction can be appropriately set so as to be uniform, and at this time, the ratio of the cross-sectional area of the flow path portion narrowed by the flow path narrowing means to the cross-sectional area of the flow path portion not narrowed is also a dispersion hole. The temperature distribution in the length direction of the outer tube can be appropriately set in consideration of the arrangement of the components, the cross-sectional area thereof, and the like.

For example, when the length of the outer tube, the arrangement of the dispersion holes, the cross-sectional area, and the like are standard, the cross-sectional area of the flow path portion narrowed by the flow path narrowing means is reduced by the cross-sectional area of the flow path portion not narrowed. 15 ~
By setting to 30%, the temperature distribution of the outer tube can be made uniform.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. That is, FIGS. 1 to 3 show first to fourth embodiments of the single-end type radiant tube device according to the present invention.
FIGS. 5A and 5B show a third embodiment.
Similarly to the above, only the distal end side of the single-end type radiant tube device is enlarged and shown.

As shown in these figures, the single-end type radiant tube device according to the present invention comprises an inner tube 2 concentrically installed inside an outer tube 1 having a closed end.
Has a configuration in which a tip is opened and a dispersion hole 3 is provided on the outer periphery. The opening of the inner tube 2 is designated by reference numeral 4. Although not shown, an exhaust portion is provided on the rear end side of the outer tube 1 and a burner portion is provided on the rear end side of the inner tube. The configurations of the exhaust portion and the burner portion are appropriate. .

Therefore, first, in the first embodiment shown in FIG. 1, the opening 4 at the tip of the inner tube 2 is formed in a diaphragm plate 5 provided at the tip of the inner tube 2. The sectional area is configured to be smaller than the sectional area of the inner tube 2. Therefore, the throttle plate 5 provided with the opening 4 is a flow path narrowing means for narrowing the flow path of the inner pipe 2. In FIG. 1, the cross-sectional area of the opening 4 is drawn as about 22% of the cross-sectional area of the inner tube 2.

In the second embodiment shown in FIG.
The opening 4 at the distal end of the inner tube 2 is formed by narrowing the inner tube 2 into a tapered shape, so that the cross-sectional area of the opening 4 is smaller than the cross-sectional area of the inner tube 2. Therefore, the tapered portion forming the opening 4 is a flow path narrowing means for narrowing the flow path of the inner tube 2. In FIG. 2, the sectional area of the opening 4 is drawn as about 30% of the sectional area of the inner tube 2.

Next, in the third embodiment shown in FIG. 3, a diaphragm plate 7 provided with a hole 6 is provided not on the tip of the inner tube 2 but on the upstream side thereof and downstream of the dispersion hole 3. The cross-sectional area of the hole 6 is smaller than the cross-sectional area of the inner tube 2. Therefore, the hole 6 provided in the throttle plate 7 is a flow path narrowing means for narrowing the flow path of the inner pipe 2. In FIG. 3, the cross-sectional area of the hole 6 is drawn as about 18% of the cross-sectional area of the inner tube 2.

In the above configuration, the high-temperature combustion exhaust gas generated at the burner portion on the rear end side of the inner pipe 2 flows to the front end side in the inner pipe 2 as shown by arrows in the figure, and In the third embodiment, the inner pipe is narrowed at the opening 4 and flows out to the distal end side of the outer pipe 1. In the third embodiment, after the flow path is narrowed by the hole 6 of the throttle plate 7, the inner pipe is 2 flows out to the distal end side of the outer tube 1 from the opening 4 at the distal end.

In this way, the flow of the combustion exhaust gas is
Alternatively, since the pressure is reduced in the hole 6, the pressure loss on the upstream side increases. Due to the internal pressure, a part of the combustion exhaust gas in the inner pipe 2 flows out through the dispersion hole 3 into the gap between the outer pipe 1 and merges with the combustion exhaust gas flowing out from the opening 4 to form the outer pipe 1 The gas flows through the gap between the inner pipe 2 and the inner pipe 2 toward the rear end side and is discharged through the exhaust part.

As described above, all or most of the high-temperature combustion exhaust gas flowing from the rear end side to the front end side of the inner pipe 2 does not flow out from the opening 4 at the front end of the inner pipe 2, but a part thereof is dispersed. 3
As a result, it is possible to prevent the distal end side of the outer tube 1 from being extremely heated locally, so that the temperature distribution in the longitudinal direction of the outer tube 1 can be made uniform.

As described above, the distribution of the amount of the combustion exhaust gas flowing out from the opening 4 of the inner pipe 2 and the amount of the combustion exhaust gas flowing out of the dispersion hole 3 are determined in consideration of the arrangement of the dispersion holes 3 and the sectional area thereof. Then, the temperature distribution in the longitudinal direction of the outer tube 1 can be appropriately set so as to be uniform. The ratio of the cross-sectional areas of the portions can be appropriately set in consideration of the arrangement of the dispersion holes 3 and the cross-sectional area thereof so that the temperature distribution in the longitudinal direction of the outer tube 1 is uniform.

For example, when the length of the outer tube, the arrangement of the dispersion holes, the cross-sectional area, and the like are standard, the cross-sectional area of the flow path portion narrowed by the flow-path restricting means is reduced to the cross-sectional area of the non-restricted flow path portion. Of 15
By setting it to ３０30%, the temperature distribution of the outer tube could be made uniform.

[0028]

As described above, the single-end type radiant tube device according to the present invention has the following effects. a. It is possible to prevent the distal end side of the outer tube from being locally heated to generate a high temperature range, and to make the temperature distribution of the outer tube uniform. b. Therefore, the temperature distribution in the furnace in which the single-end type radiant tube device of the present invention is installed can be made uniform. c. By preventing local heating of the outer tube, the life of the outer tube can be extended.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a first embodiment of a single-ended radiant tube device according to the present invention.

FIG. 2 is a longitudinal sectional view showing a main part of a second embodiment of the single-ended radiant tube device according to the present invention.

FIG. 3 is a longitudinal sectional view of a main part showing a third embodiment of the single-ended radiant tube device according to the present invention.

FIG. 4 is a longitudinal sectional view showing the entire configuration of a conventional single-ended radiant tube device.

FIG. 5 is an enlarged vertical sectional view of a main part of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer pipe 2 Inner pipe 3 Dispersion hole 4 Opening 5 Aperture plate 6 Hole 7 Aperture plate

Claims (5)

[Claims] An inner tube is concentrically installed inside an outer tube having a closed end, and the inner tube has a configuration in which a distal end is opened and a dispersion hole is provided on an outer periphery. In the single-end type radiant tube device having an exhaust portion and a burner portion on the rear end side of the inner tube, the inner tube has a flow path restricting means configured to restrict a flow path downstream of the dispersion hole. Single-end type radiant tube device 2. The single-ended radiant tube device according to claim 1, wherein the flow path restricting means is formed at a tip of the inner tube. 3. The single-end type radiant tube device according to claim 2, wherein a flow path restricting means is formed by narrowing a tip end of the inner pipe into a tapered shape. 4. The single channel device according to claim 1, wherein the flow path restricting means is provided with a restrictor plate provided with a hole upstream of the distal end of the inner pipe and downstream of the dispersion hole. End type radiant tube device 5. The method according to claim 1, wherein a cross-sectional area of the flow path portion narrowed by the flow path narrowing means is set to 15 to 30% of a cross-sectional area of the flow path portion not narrowed. Single-ended radiant tube device