TWI628406B - Radiant tube-type heating device - Google Patents

Abstract

The invention relates to a radiant tube type heating device, comprising: a heat exchanger, which is disposed in a hollow portion on the other end side of a radiant tube and pre-heats the air for combustion with the heat of the exhaust gas, wherein The heat exchanger includes: a ceramic body having a cylindrical shape; an annular flange located in a base end portion of the heat exchanger; and a flow path for heat dissipation of the exhaust gas, which runs along the body The outer peripheral surface is spirally formed; a heat-absorbing flow path for combustion air is spirally formed in the main body; and a return path for preheated air for combustion is formed along the axial direction of the main body In the central part of the main body, the annular flange is sandwiched between a pair of tube end faces opposed to each other via a pair of relatively thick ring pads, the pair of tube end faces are located on the other end side of the radiation tube, And among them, a tubular body having elasticity and heat insulation performance is continuously and coaxially provided with an opening on a base end side of the return path in the heat exchanger.

Description

Radiant tube heating device

The present invention relates to a radiant tube heating device that can perform heating, for example, while maintaining clean air in a heat treatment furnace, and has excellent thermal efficiency and durability.

A heat exchanger for a radiant tube burner has been proposed, which includes a radiant tube that passes through the furnace wall of the annealing furnace and has a side U shape in a side view, and is arranged in the top (upstream) side of the radiant tube Combustion burner (combustion burner) and a heat exchanger arranged in the rear (downstream) side of the radiant tube. The heat exchanger pre-heats the combustion air with the heat contained in the combustion exhaust gas, and the combustion air is supplied to the combustion burner. The heat exchanger includes a heat exchanger main body and a heat exchanger lifting unit located between the heat exchanger main body and the radiant tube on a rear end side. The main system of the heat exchanger is composed of a double metal pipe, which sucks the combustion air from the central side, turns the combustion air in its top part and then sucks it to the outside. The heat exchanger lifting unit is made of a copper-based heat conductor or radiator and has a spiral shape (see, for example, Patent Document 1).

A radiant tube type heating device is also proposed, which includes the similar radiant tube described above, a connecting tube arranged on one end (upstream) side of the radiating tube, and a burner provided in a middle (central) part of the connecting tube. The radiant tube heating device further includes an exhaust gas return pipe connected to the other end (downstream) of the radiant tube and a spiral plate-shaped communication tube surrounding the burner. The air chamber is mixed with a SiC (ceramic) -based spiral heat exchanger for combustion air. The exhaust gas return pipe communicates with the connection pipe, and the heat exchanger is disposed in the connection pipe (refer to, for example, Patent Document 2).

A ceramic (SiC, etc.) spiral heat exchanger used in a radiant tube heating device according to Patent Document 2 has excellent heat resistance and thermal shock resistance. Therefore, as in the case of the heat exchanger for a radiant tube burner according to Patent Document 1, it can be used in a manner arranged in the rear (downstream) side of the radiant tube.

However, for example, in the case of a metal tube-based radiant tube having a side U shape in a side view, the radiant tube comes into contact when a distortion such as a downward sagging in the furnace is caused due to a time-dependent change. Local stress and pressure are applied to a plurality of parts of the SiC-based heat exchanger arranged in the radiant tube. As a result, in some cases, brittle fracture may occur near the flange on the rear end side of the SiC-based heat exchanger.

Patent Document 1: JP-A-2014-92329

Patent Document 2: JP-A-2013-194977

The present invention has been made to solve the above problems. It is an object of the present invention to provide a radiant tube type heating device in which, even in the event of distortion of a metal radiant tube attributable to a time-dependent change or the like, in the other end (downstream) side of the radiant tube The ceramic heat exchanger is not prone to brittle fracture.

To achieve this, the present invention is made based on the following concepts. One of the concepts is to provide a relatively large thickness for the packings used to clamp the flanges on the rear end side of the ceramic heat exchanger from the two tube end faces so that the ceramic heat exchanger is fixed to the radiation The other end (downstream) side in the tube. Another concept is to prevent There are more metal tubes that stop receiving the preheated air for combustion drawn from the central part of the heat exchanger than the flange inserts into the heat exchanger.

The radiant tube heating device (state 1) according to the present invention includes: a radiant tube having a turning portion protruding into a furnace on the top side thereof, and two end portions passing through a furnace body; a combustion spray A burner provided in a central portion of the hollow portion on one end side of the radiant tube and coaxially disposed with the hollow portion; and a heat exchanger provided in the hollow portion on the other end side of the radiant tube The air for combustion is preheated with the heat of the exhaust gas, wherein the heat exchanger comprises: a ceramic body having a cylindrical shape; an annular flange located in a base end portion of the heat exchanger; a A heat dissipation flow path for the exhaust gas is spirally formed along the outer peripheral surface of the main body; a heat absorption flow path for combustion air is spirally formed in the main body; and a preheating flow for combustion A return path of hot air is formed in a central portion of the main body along an axial direction of the main body, wherein the annular flange is sandwiched between a pair of opposite end faces of the tube via a pair of relatively thick annular gaskets , The end of the pair of tubes is located in the radiant tube The other end portion side, and wherein a tubular body having insulation performance and elasticity of the opening portion and the base end of the one side of the return path of the heat exchanger is continuously and coaxially disposed.

The following effects (1) and (2) can be achieved with a radiant tube heating device having the above structure.

(1) In the ceramic heat exchanger, the annular flange at its base end is clamped in the other end of the radiant tube via the pair of relatively thick annular gaskets according to, for example, bolt and nut fastening Between the pair of pipe end faces opposite to each other. Thus, even in the event that a part of the radiant tube in the furnace is distorted (e.g., downward bending attributable to time-dependent changes, etc.), the heat exchanger can easily take to follow the The bent posture, and therefore, the possibility of brittle fracture of the heat exchanger in the vicinity of the flange can be removed or suppressed to a significant extent.

(2) The tubular body having elasticity and heat insulation performance is coaxially connected to the opening portion on the base end side of the return path of the preheated air for combustion in the heat exchanger. None of the metal pipes communicate with the interior of the return path. Therefore, even in the case where the twist of the radiant tube occurs as described above, the heat exchanger can easily and reliably follow the displacement near the flange of the heat exchanger via the tubular body. Therefore, the possibility of brittle fracture can be removed or reliably prevented.

The radiant tube may be a metal tube made of cast steel or the like, and a top end portion thereof may have a side U shape or a side W shape.

The furnace system is, for example, a main furnace wall of a sintering furnace, a heat treatment furnace like an annealing furnace, and the like. It may also be the top of the heat treatment furnace or the like.

The combustion burner burns the mixed gas of the preheated air and a fuel, and emits (emits) an elongated flame from an opening portion at the top end thereof along the axial direction of the hollow portion into the center portion of the radiant tube.

Examples of ceramics constituting the heat exchanger include SiC, WC, B ₄ C, alumina (Al ₂ O ₃ ), aluminum nitride, TiN, and mullite. In view of the excellent thermal conductivity and excellent thermal shock resistance of SiC, SiC is particularly recommended.

Even when complex internal and external shapes are required, The heat exchanger is easily produced using a three-dimensional (3D) printer.

The outer peripheral surface of the main body of the heat exchanger may be in contact with or near the inner wall surface of the hollow portion of the radiant tube.

The main body of the heat exchanger has a top end portion on the turning portion side of the radiant tube, which has, for example, a hemispherical shape. A gas introduction groove communicating with a plurality of flow paths for heat dissipation may be located in that tip portion.

The flow path for heat dissipation and the flow path for heat absorption of the heat exchanger may be any spiral groove or spiral hollow portion (hole).

The dunnage is, for example, a sealing material, in which a plurality of annular insulation materials including paper-based ceramic fibers are stacked.

The present invention also includes the radiant tube heating device (Aspect 2), wherein each of the pair of annular pads has an unloaded thickness of at least 9 mm and has 4mm to 8mm thickness.

According to this configuration, the annular flange of the ceramic heat exchanger is clamped by the annular pad having a thickness of at least 9 mm, which is at least twice as large as a standard annular pad having a thickness of several millimeters (about 2 mm to about 3 mm). , And the thickness when clamping the annular flange is between 4mm and 8mm. Therefore, even in the case where downward twisting of a part of the radiant tube in the furnace occurs as described above, the above-mentioned effect (1) can be reliably ensured.

The present invention also includes the radiant tube heating device (Aspect 3), in which the same plurality of flow paths for heat dissipation and flow paths for heat absorption are spirally and adjacently formed on the outer peripheral surface of the main body and Of the inner peripheral surface, and among them, one of the outer peripheral surfaces of the tubular body is surrounded by a metal sheath having a plurality of claw members protruding from the top surface thereof, and the claw members are respectively locked to a flow for absorbing heat. In the opening on the base end side of the road.

According to this configuration, the base end side of the flow path for heat absorption is allowed to be coaxial with the tubular system and reliably communicate with each other by the sheath. Therefore, even in the case where the twist of the radiant tube occurs as described above, the preheated air for combustion can be reliably supplied to the burner on the end side (effect (3)).

The sheath is obtained, for example, from a thin stainless steel plate that is punched and bent and integrally molded into a cylindrical shape by welding or the like.

The invention also includes the radiant tube heating device (Aspect 4), wherein the tubular system is made of a cylindrical body made of a material containing a binder resin and ceramic powder, or is made of the material and is coaxial with each other A plurality of connected circular members are formed.

According to this configuration, even when the twist of the radiant tube occurs as described above, the base end side of the flow path for heat absorption and the tubular body are reliably communicated with each other. Therefore, the effects (2) and (3) can be reliably ensured.

The tubular body may be a tubular body in which a cylindrical body made of the material containing an adhesive resin and a ceramic powder and a plurality of ring members made of the material are used simultaneously in a coaxial continuous manner.

1‧‧‧ radiant tube heating device

2‧‧‧ radiant tube

2a‧‧‧One end (upstream side)

2b‧‧‧ the other end (downstream side)

2c‧‧‧Turning section

3‧‧‧ Hollow

4‧‧‧ burner

5‧‧‧ end plate

6‧‧‧ exhaust pipe

7‧‧‧Horizontal Division

8‧‧‧ supply pipe

9‧‧‧ bracket

10‧‧‧ Bellows

11‧‧‧Air supply pipe

12‧‧‧L-shaped tube

13, 14‧‧‧ tube end (tube end)

13h, 14h ‧‧‧through hole

15‧‧‧ Branch

16‧‧‧ metal tube

17‧‧‧ Thermal Radiator

18‧‧‧ intermediate shaft

19‧‧‧Heat radiation structure

20‧‧‧ heat exchanger

21‧‧‧ main body

21a‧‧‧Return path

22‧‧‧ tip

23‧‧‧Gas introduction tank

24‧‧‧ flume

24a‧‧‧groove

25‧‧‧ orifice

25a‧‧‧ linear orifice

26‧‧‧ cylindrical tablets

27‧‧‧ flange

28‧‧‧ opening

30‧‧‧ Tubular body

30r‧‧‧Ring

31‧‧‧Hollow

32‧‧‧ sheath

33‧‧‧ Paw Piece

b‧‧‧ bolt

n‧‧‧nut

F‧‧‧ Flame

W‧‧‧furnace wall (furnace body)

P‧‧‧Ring cushion

t1, t2‧‧‧thickness of ring pad

IN‧‧‧ Inside the furnace

OUT‧‧‧ Outside the furnace

Fig. 1 is a vertical sectional view illustrating a specific example of a radiant tube heating device according to the present invention.

Fig. 2 is a perspective view of a heat exchanger arranged in the other end side of the radiant tube.

Fig. 3 is a perspective view of the heat exchanger as viewed from the rear end side.

Fig. 4 is an enlarged vertical sectional view illustrating the other end side of the radiant tube heating device.

Fig. 5 is a perspective view illustrating a specific example in which a tubular body and a sheath are mounted on the rear end side of the heat exchanger.

6A and 6B are partial enlarged views illustrating a state in which the flange of the heat exchanger is sandwiched on the other end side of the radiation tube via a pair of annular spacers.

Hereinafter, a specific example of the present invention will be described.

FIG. 1 is a vertical sectional view of a specific example of a radiant tube heating device (hereinafter, simply referred to as a heating device) 1 according to the present invention.

As shown in FIG. 1, the heating device 1 includes a radiant tube 2 that passes through a vertical furnace wall (furnace body) W in a horizontal direction and is coaxially disposed at one end (upstream) of the radiant tube 2 with a central portion of the hollow portion 3. The combustion burner 4 on the 2a side and the heat exchanger 20 provided in the hollow portion 3 on the other end (downstream) 2b side of the radiant tube 2.

The furnace wall W is, for example, a furnace body constituting a heat treatment furnace such as an annealing furnace.

The radiant tube 2 is, for example, an integrated article made of cast steel and having a tubular shape. The radiant tube 2 has a generally side U-shape in a side view, passes horizontally through the furnace wall W from the furnace OUT to the furnace IN, and has a semi-circular shape (U-shape) at its top end on the furnace IN side. ) The protruding turn 2c. The hollow portion 3 is continuously formed along the entire length of the radiation tube 2, and the entire length covers the turning portion 2 c and the two end portions 2 a and 2 b.

As shown in FIG. 1, a heat radiator 17 made of ceramics described later is disposed between the turning portion 2 c and the heat exchanger 20 in the hollow portion 3 of the radiating tube 2. The heat radiator 17 is composed of an intermediate shaft 18 provided along the central portion of the hollow portion 3 and a heat radiation frame 19 spirally wound around the intermediate shaft 18.

The combustion gas generated by the combustion of the fuel in the burner 4 and the preheated air for combustion passes through the tube wall IN of the radiant tube 2 and passes through the turning portion 2c at the same time. Even after passing through the turning portion 2c, the heat radiator 17 further transmits the heat of the combustion gas to the IN side of the furnace by allowing the combustion gas to spirally flow along the heat radiation structure 19.

The heat exchanger 20 is made of, for example, silicon carbide (SiC: carbide-based ceramics) having both excellent thermal conductivity and excellent thermal shock resistance. The heat exchanger 20 has an appearance as shown in FIGS. 2 and 3 and a cross section as shown in FIGS. 1 and 4. The heat exchanger 20 is produced by, for example, a 3D printer.

As shown in FIGS. 2 and 3, the heat exchanger 20 has a cylindrical body 21, a hemispherical tip portion 22, and a disk-shaped flange 27 on the proximal end side of the body 21. The main body 21, the distal end portion 22, and the flange 27 are integrated with each other. The gas introduction groove 23 is formed in the distal end portion 22 symmetrically in the radial direction. As an example, the number of the gas introduction grooves 23 in this specific example is six (plurality). Six (plural) flow grooves (flow paths for heat radiation) 24 having a spiral shape and individually communicating with the six gas introduction grooves 23 are formed on the outer peripheral surface of the main body 21 in parallel with each other.

The gas introduction groove 23 and the flow groove 24 for heat radiation are used so as to preliminarily heat the combustion air that has recently been supplied to the combustion burner 4 by the exhaust gas of the combustion gas passing through the heat radiator 17. Six grooves 24 a parallel to the axial direction of the main body 21 are attached to the flange 27 side of the individual flow groove 24 for heat dissipation.

A return path (through hole) 21 a having a cylindrical columnar shape along the axial direction of the main body 21 is formed in a central portion of the main body 21. Six (plural) flow holes (flow paths for heat absorption) 25 for heat absorption are formed in the interior of the main body 21 surrounding the return path 21a in parallel with each other. Each of the flow holes 25 for heat absorption has a spiral shape as a whole and has an elongated rectangular cross section.

As shown in FIGS. 1 and 4, six flow holes 25 for absorbing heat and six flow grooves 24 for radiating heat are alternately positioned along the axial direction of the main body 21. Each of the six flow holes 25 for heat absorption communicates with the return path 21 a in the hollow portion in the tip portion 22. On the flange 27 side, each of the six flow holes 25 for absorbing heat is parallel to the body 21 Axial flow hole 25a. The flow holes 25 a and the grooves 24 a are alternately formed along the circumferential direction of the main body 21. The six flow holes 25 for heat absorption are respectively communicated with the six openings 28 formed along the circle on the side of the base end of the flange 27.

In the heat exchanger 20, as shown in FIG. 4, a cylindrical piece 26 formed of an insulating material is wound around the outer peripheral surface of the main body 21 between the outer peripheral surface of the main body 21 and the other end portion 2 b side of the radiation tube 2. Therefore, leakage between adjacent flow grooves 24 for heat dissipation is prevented. In addition, the heat-resistant metal pipe 16 is inserted into the return path 21 a along substantially the entire length of the return path 21 a (excluding the tip end portion 22).

The branch portion 15 for exhaust is in communication with six flow grooves 24 for heat radiation, and is formed on the other end portion 2b side of the radiation tube 2. The exhaust pipe 6 is vertically connected to the branch portion 15.

As shown in FIGS. 1 and 4, a tube end portion (tube end surface) 14 of the other end portion 2 b of the radiation tube 2 and a tube end portion (tube end surface) 13 of the L-shaped tube 12 connected to the gas supply tube 11 are borrowed. The circumferential portion of the flange 27 of the heat exchanger 20 is clamped (clamped) by a pair of annular pads P, which are relatively thick and are on the left and right (front and back) sides of the drawing.

The ring-shaped gasket P is, for example, a sealing material in which a plurality of ring-shaped insulating materials formed of paper-based ceramic fibers are stacked. The ring pad P has a thickness t1 of at least 9 mm when no load is shown in FIG. 6A.

As shown in FIG. 6B, when the flanges 27 of the heat exchanger 20 are tightened with a plurality of bolts b and a plurality of nuts n between the tube ends 13 and 14, the thickness of each of the ring pads P is between Between about 4mm and about 8mm.

A plurality of through holes 13h and 14h are formed parallel to the axial direction to pass through the tube ends 13 and 14. Once the peripheral portion of the flange 27 is superimposed on the pair of annular pads P, the bolt b is inserted into the through holes 13h and 14h and the nut n is placed on the top of their male thread portion. The side spiral connection can be used to lock the circumferential portion of the flange 27 from both sides by the ring pad P. As a result, the heat exchanger 20 is brought into a fixed state in the hollow portion 3 on the other end portion 2 b side of the radiant tube 2.

As shown in FIG. 6B, it is desirable to form a small gap between the outer circumferential side of the flange 27 and the inner circumferential portions of the pipe ends 13 and 14.

As shown in FIG. 1, a horizontal portion 7 of a supply pipe 8 that supplies air for combustion is provided in the L-shaped pipe 12. The tubular body 30 has elasticity and heat insulation performance, and is arranged coaxially between the inside of the horizontal portion 7 and the return path 21 a of the heat exchanger 20. As shown in FIGS. 4 and 5, the tubular body 30 is a cylindrical body, in which a plurality of ring members 30r are coaxially connected to each other, and each of the ring members 30r is formed by molding a ceramic powder-containing adhesive resin. obtain. The tubular body 30 has a hollow portion 31 therein, and the hollow portion 31 communicates with the return path 21 a of the heat exchanger 20. The plurality of ring members 30r are bonded to each other to form the tubular body 30.

As shown in FIGS. 4 and 5, the tubular body 30 is inserted into and supported by the inner side 35 of the metal sheath 32 surrounding the outer peripheral surface of the tubular body 30. The sheath 32 has six (plural) claw members 33 protruding from the front end face 34 side. The sheath 32 is mounted on the outer side of the flange 27 by inserting and locking six (plural) claw pieces 33 to the six opening portions 28 formed in the rear end face of the flange 27 of the heat exchanger 20, respectively. .

In other words, the metal pipe 16 inserted into the return path 21 a of the heat exchanger 20 and the horizontal portion 7 of the supply pipe 8 that supplies air for combustion are in communication with each other via the tubular body 30.

As shown in FIG. 1, a supply pipe 8 for supplying air for combustion can communicate with a bracket 9 supported by an end plate 5 through a bellows 10. The end plate 5 blocks the tube end of the radiant tube 2 on the side of the end portion 2a, and the bellows 10 is made of a heat-resistant material and can Enough to stretch in the vertical direction. The bracket 9 passes through an end plate 5 for blocking the end surface of the tube in the end portion 2a and the combustion burner 4 is mounted on the top of the bracket 9. The support 9 sucks the gas for combustion into the combustion burner 4 and performs ignition, wherein the gas system for combustion is obtained by mixing a previously atomized fuel with preheated air for combustion. As a result, the flame F shown in FIG. 1 is ejected from the combustion burner 4.

The effects of the heating device 1 will be described below.

As shown in FIG. 1, the flame F is ejected from the combustion burner 4 in the hollow portion 3 on the end 2 a side of the radiant tube 2, and a combustion gas heated by the flame F is generated. As shown by a white arrow in FIG. 1, the combustion gas flows near the turning portion 2 c and the heat radiator 17, and is supplied to the heat exchanger 20 on the other end portion 2 b side. During the supply of the combustion gas, the heat contained in the combustion gas is radiated to the IN in the furnace through the wall of the radiant tube 2 to become radiant heat, and is used to heat the IN in the furnace to maintain a predetermined temperature range. Radiation of the radiant heat is promoted by the combustion gas spiraling through the heat radiator 17.

As shown by the gray arrows in FIGS. 1 and 4, the combustion gas supplied to the front end portion 22 side of the heat exchanger 20 in the hollow portion 3 on the other end portion 2 b of the radiant tube 2 passes through six gas introduction grooves 23 And six spiral flow grooves 24 for heat dissipation which are respectively communicated with the six gas introduction grooves 23. Then, the combustion gas is discharged from the exhaust pipe 6 to the outside.

As shown by the thin white arrows in FIGS. 1 and 4, fresh air for combustion passes from the air supply pipe 11 through the L-shaped pipe 12. Then, the fresh air for combustion is sucked into the plurality of openings 28 opened in the flange 27 of the heat exchanger 20. The fresh air for combustion passes through the linear flow holes 25 a and the spiral flow holes 25 for heat absorption, and is delivered to the hollow portion in the tip portion 22. The combustion air passes through the combustion gas flowing through the plurality of flutes 24 for heat dissipation while passing through the plurality of flow holes 25 for absorbing heat. The body's thermal conduction is gradually heated (heated) in advance.

As shown by a thin white arrow, the preheated air for combustion is supplied from the hollow portion located in the top end portion 22 of the heat exchanger 20 through the inside of the metal pipe 16 inserted into the return path 21a to communicate with the outside of the flange 27 Vacuum portion 31 of a tubular body 30. After passing through the tubular body 30, the air for combustion passes through the supply pipe 8 including the horizontal portion 7, the bellows 10, and the bracket 9. Then, the air for combustion is supplied to the combustion burner 4 and mixed with the fuel, and a flame F is generated.

In the case where the above-mentioned operation is repeated for a long time, in some cases, a twist like a slight downward bend occurs on the IN side of the furnace including the turning portion 2c of the radiant tube 2. For example, in some cases, the vicinity of the turning portion 2c of the radiant tube 2 is subjected to a twist deformation in the form of a downward displacement of several millimeters.

In this specific example, as shown in FIGS. 4 and 6B, the flange 27 of the heat exchanger 20 is sandwiched between the tube end portion 14 and the tube end portion of the L-shaped tube 12 located at the other end portion 2 b of the radiation tube 2. 13 between the ring pads P. The annular pad P has a relatively large unloaded thickness t1 and a thickness t2 reduced by about 1 mm to about 5 mm due to the screwing with the bolt b and the nut n.

As a result, in the case where the radiant tube 2 is subjected to the above-mentioned twisting deformation, the flange 27 and the main body 21 of the heat exchanger 20 can easily follow the other of the radiating tube 2 subjected to the twist within the range of the thickness variation of the pair of annular pads P The hollow part 3 in the one end part 2b. For example, the annular gasket P adjacent to the pipe end 14 is changed so that its upper side is significantly compressed and its lower side is slightly contracted, and the annular gasket P adjacent to the pipe end 13 is changed, So that its upper side shrinks slightly, while its lower side is significantly compressed.

Thus, the above-mentioned effects (1) to (3) can be reliably achieved with the heating device 1. In addition, even the IN side in the furnace of the radiant tube 2 is subjected to a relatively large earthquake which causes vertical shaking. In the case, the above effects (1) to (3) can still be achieved. In this case, it can be said that the heating device 1 is durable and not easily damaged even in a relatively large earthquake.

The invention is not limited to the specific examples described above.

For example, the outer shape of the turning portion 2c of the radiant tube 2 may be a side M shape (roughly Σ) or a side W shape.

The heat exchanger 20 can be produced from ceramics (except SiC) having excellent thermal conductivity and thermal shock resistance.

The outer shape of the top end portion 22 of the heat exchanger 20 may be conical or semi-elliptical.

The flow slot 24 for heat dissipation of the heat exchanger 20 may be a flow hole for heat dissipation arranged in the main body 21 and having a spiral hollow hole similar in shape to the above.

The metal pipe 16 inserted into the return path 21 a of the heat exchanger 20 may be omitted. Alternatively, the metal pipe 16 may be used, and the flow hole 25 for heat absorption may be a flow groove for heat absorption which leads to the return path (through hole) 21a side and has a shape similar to that described above.

The tubular body 30 may be a cylindrical body made of the above-mentioned materials and having a hollow portion 31 among them. Alternatively, the cylindrical body and the plurality of ring members 30r may be arranged coaxially and continuously.

The tubular body 30 may be mounted on the flange 27, and one end (top end) side of the tubular body 30 is inserted into the return path 21 a or the metal pipe 16 of the heat exchanger 20. In this case, a tubular body 30 having a decreasing outer diameter and a sheath 32 having a decreasing inner diameter are used, and the claw member 33 protrudes from the large-diameter portion of the sheath 32.

Industrial applicability

According to the present invention, a radiant tube type heating device can be reliably provided. Among them, even in the case where the distortion of the metal radiant tube can be attributed to a time-dependent change or the like, the ceramic heat exchanger disposed in the other end (downstream) side of the radiant tube is not prone to brittle fracture.

Although the specific examples of the present invention have been described in detail above, the present invention should not be construed as being limited to the specific examples, and it is obvious that various changes and modifications can be made without departing from the spirit and scope of the present invention.

The present invention is based on Japanese Patent Application No. 2016-148912 filed on July 28, 2016, and the contents are incorporated herein by reference.

Claims (5)

A radiant tube type heating device includes: a radiant tube having a turning portion protruding into a furnace on a top side thereof, and two ends passing through a furnace body; a combustion burner provided at A central portion of the hollow portion on one end side of the radiant tube and coaxially disposed with the hollow portion; and a heat exchanger provided in the hollow portion on the other end side of the radiant tube and using the heat of the exhaust gas The air for combustion is pre-heated, wherein the heat exchanger includes: a ceramic body having a cylindrical shape; an annular flange located in a base end portion of the heat exchanger; and a heat exchanger for the exhaust gas. A heat dissipation flow path is spirally formed along the outer peripheral surface of the main body; a heat absorption flow path for combustion air is spirally formed in the main body; and a preheated air supply for combustion A return path is formed in a central portion of the main body along an axial direction of the main body, wherein the annular flange is sandwiched between a pair of opposite pipe end faces via a pair of relatively thick annular gaskets, the pair The end of the tube is located in the radiant tube One end portion side, and wherein a portion having an opening and one of the elastic tubular body with a proximal end of the insulation performance of the return path of the heat exchanger side and coaxially disposed continuously. The radiant tube heating device of claim 1, wherein each of the pair of annular pads has an unloaded thickness of at least 9 mm and has a thickness of 4 to 8 mm in a state of sandwiching the annular flange of the heat exchanger. thickness. For example, the radiant tube heating device of claim 1, wherein the same plurality of flow paths for heat radiation and heat paths for heat absorption are spirally and adjacently formed in the outer peripheral surface and the inner peripheral surface of the main body, respectively, And, one of the outer peripheral surfaces of the tubular body is surrounded by a metal sheath having a plurality of claw members protruding from the top surface thereof, and the claw members are locked to the base end side of the flow path for heat absorption, respectively. On the opening. For example, the radiant tube heating device of claim 2, wherein the same plurality of flow paths for heat dissipation and flow paths for heat absorption are spirally and adjacently formed on the outer peripheral surface and the inner peripheral surface of the main body, respectively, And, one of the outer peripheral surfaces of the tubular body is surrounded by a metal sheath having a plurality of claw members protruding from the top surface thereof, and the claw members are locked to the base end side of the flow path for heat absorption, respectively. On the opening. The radiant tube heating device according to any one of claims 1 to 4, wherein the tubular system is a cylindrical body made of a material containing a binder resin and a ceramic powder, or is made of the material and is mutually A plurality of coaxially connected annular members are formed.