JPH0526419A - Radiant tube burner - Google Patents

Abstract

PURPOSE:To improve a combustion efficiency and a heat transfer efficiency of a radiant tube burner and make a uniform temperature distribution at a heat transfer surface. CONSTITUTION:Mixture gas premixed with gas fuel and primary air is supplied into an inner tube 6 inserted into an outer tube 2 with the first spacer 7 being applied in it. A combustion tube 8 having a burner nozzle 15 installed therein is inserted with the second clearance 9 being set. Heat-resistant particle group 17 sealed into the outer tube 2 are blown up by a combustion gas flow flowed out of a lower end in the combustion tube 8 and circulated and flowed under their dispersed condition within the first clearance 7 and the second clearance 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiant tube burner applied as a heat source for an atmosphere heat treatment furnace, a metal melting furnace and the like.

[0002]

2. Description of the Related Art As a conventional technique, for example, Japanese Patent Laid-Open No. 63-6 is available.
There is a publication 5217. This publication discloses a tube burner in which a heat-resistant particle group contained in an outer tube is vertically moved by combustion gas.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to further improve combustion efficiency and heat transfer efficiency and make the temperature distribution on the heat transfer surface more uniform in a radiant tube burner using a heat resistant particle group as a heating medium. It is what

In the radiant tube burner of the present invention, gas fuel and primary air are premixed in an inner tube which is inserted into a vertically-arranged bottomed cylindrical outer tube with a first gap. A combustion tube, into which a burner nozzle to which mixed gas is supplied, is inserted, is inserted through a second gap, and is blown up into the outer tube by a flow of combustion gas flowing from a lower end of the combustion tube. A heat-resistant particle group that circulates and flows in the first gap and the second gap is enclosed.

[0005]

The mixed gas in which the gas fuel and the primary air are premixed is supplied into the combustion tube inserted through the inner tube inserted through the outer tube with the first gap and the inner tube inserted through the second tube with the second gap. And then burned, the heat-resistant particle group enclosed in the outer tube is blown up by the combustion gas flow flowing out from the lower end in the combustion tube, so that the inside of the first gap and the inside of the second gap. Are repeatedly circulated and flowed in a diffused state.

[0006]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, a state in which each particle diffuses a particle group heated by the combustion gas during combustion of the air-fuel mixture over the entire first and second gaps It is possible to make the temperature distribution on the heat transfer surface of the outer tube uniform by circulating and flowing the heat to uniformly heat the entire inside of the outer tube. Further, since the mixed gas in which the gas fuel and the primary air are premixed is supplied to the burner nozzle and burned, the mixed state of the gas fuel and the air is made uniform, the ignitability is improved, and the stable combustion state is continued. In addition, the carbon monoxide concentration can be reduced, and the stable combustion range can be expanded.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the present invention will be described with reference to the drawings. In the radiant tube burner B, a disc-shaped flange 1 that is fastened to a mounting surface such as a furnace wall is vertically inserted by being inserted through the center of the flange 1 and is a bottomed cylinder made of stainless steel or ceramic material. The outer tube 2 formed in a shape is fixed.

The inner wall surface of the bottom of the outer tube 2 is formed in a hemispherical shape, while the opening at the upper end of the outer tube 2 is closed by a cover plate 3 and a discharge port 4 opened near the upper end of the outer tube 2. An exhaust gas pipe 5 is connected to the.

Inside the outer tube 2, there is a first inner tube 6 which is formed of a stainless material or a ceramic material in a cylindrical shape and has a length shorter than the length of the outer tube 2.
Is inserted concentrically with a gap 7 between the inner tube 6 and a funnel-shaped taper portion 6a having an inner diameter and an outer diameter gradually increasing in the vicinity of the upper end thereof.
Around the tapered portion 6a, there is formed a throat portion 7a whose cross-sectional area gradually decreases upward.

A combustion tube formed in the inner tube 6 in a cylindrical shape of a stainless material or a ceramic material and having a length longer than the length of the outer tube 6, and being inserted near the upper end of the outer tube 2. 8 is inserted through a second gap 9, and a divergent tapered portion 8 having an inner diameter and an outer diameter gradually increasing downward near the lower end of the combustion tube 8.
a is formed, and a first communication port 10 that communicates the inside of the combustion tube 8 and the first gap 7 is formed between the lower end edge of the tapered portion 8a and the inner wall surface of the lower end of the outer tube 2. A second communication port 11 that connects the first gap 7 and the second gap 9 is formed between the tapered portion 8a and the lower end edge of the inner tube 6.

An anti-scattering net 18 is installed in the upper portion of the outer tube 2 and has a large number of meshes for allowing gas to flow therethrough, the outer peripheral edge of which is gripped by the flange 1 and which covers the gaps 7 and 9 above. ing.

An inflow port 19 for allowing secondary air to flow into the combustion tube 8 is opened near the upper end of the combustion tube 8, and a secondary air supply pipe line 20 is connected to the inflow port 19.

A gas pipe 12 connected to a gas supply line 13 for supplying a mixed gas in which gas fuel and primary air are premixed is inserted at an upper portion of the combustion tube 8 with a gap therebetween. The ignition plug 14 is inserted through the central portion.

A gas pipe 1 is provided in the upper part of the combustion tube 8.
A burner nozzle 15 connected to the tip of 2 is inserted, and a secondary air flow passage 16 for supplying secondary air to the tip of the burner nozzle 15 is formed between the combustion tube 8 and the gas pipe 12.

When the secondary air is sent to burn the mixed gas, the combustion gas flows out from the lower end of the combustion tube 8 through the first communication port 10 at a high flow velocity and flows in the first gap 7. The first gap 7 is reversed and flows upward in a reverse direction.
At the throat portion 7a, the inside of the throat portion 7a ascends and flows through the outlet 4 while the flow velocity is increased.

A first communication port 10 is provided in the outer tube 2.
A heat-resistant particle group 17 such as alumina particles capable of rising due to the flow of the combustion gas flowing out from is enclosed. At the time of combustion of the mixed gas, the particle group 17 accumulated in a dense state near the bottom of the outer tube 2 is blown up by the combustion gas flow flowing out from the lower end of the combustion tube 8 and burned in the first gap 7 in a diffused state. The gas flows upward together with the gas, flows from the upper end in the first gap 7 to the upper end in the second gap 9, and falls and flows in the second gap 9 by its own weight to flow in the second gap 9
It flows from the lower end inside to the lower end inside the first gap 7 through the second communication port 11 again, and repeatedly circulates and flows between the first gap 7 and the second gap 9.

Next, the operation and effect of the embodiment having the above-mentioned structure will be described. In this example, a mixed gas obtained by premixing gas fuel and primary air is introduced into the inner tube 6 inserted with a first gap 7 in the outer tube 2 having a bottomed cylindrical shape installed vertically. The combustion tube 8 in which the burner nozzle 15 to be supplied is inserted through the second gap 9 and is blown up into the outer tube 2 by the combustion gas flow flowing out from the lower end of the combustion tube 8. A heat-resistant particle group 17 circulating and flowing in the gap 7 and the second gap 9 is enclosed.

Therefore, the particle group 17 heated by the combustion gas during the combustion of the air-fuel mixture is circulated and flowed in a state in which each particle is diffused throughout the first and second gaps 7 and 9, and the outer tube 2 is It is possible to uniformly heat the entire inside and uniformize the temperature distribution on the heat transfer surface of the outer tube 2.

Further, since the mixed gas in which the gas fuel and the primary air are premixed is supplied to the burner nozzle 15 and burned, the mixed state of the gas fuel and the air is made uniform, the ignitability is improved, and stable combustion is achieved. The state can be continued, the carbon monoxide concentration can be reduced, and the stable combustion range can be expanded.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a radiant tube burner showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

 2 Outer tube 6 Inner tube 7 First gap 8 Combustion tube 9 Second gap 15 Burner nozzle 17 Particle group

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Yamada 507-2, Takaracho, Tokai City, Aichi Prefecture Toho Gas Co., Ltd.

Claims (1)

Claims: 1. A gas fuel and a primary air are premixed in an inner tube which is inserted into a vertically-arranged bottomed cylindrical outer tube with a first gap. The combustion tube in which the burner nozzle to which the mixed gas is supplied is inserted through the second gap, and is blown into the outer tube by the flow of combustion gas flowing out from the lower end of the combustion tube. A radiant tube burner in which a heat-resistant particle group circulating and flowing in the first gap and the second gap is enclosed.