Recuperator

Abstract

To provide a recuperator having an improved heat exchange function between combustion exhaust gas and combustion air.SOLUTION: This recuperator 3 exchanges heat between combustion exhaust gas flowing in a radiant tube 1 and combustion air used for burning a burner used for the radiant tube 1, and a plurality of groove parts 7 extending in a zigzag shape in the longitudinal direction of the recuperator 3 are formed on an outer surface of the recuperator 3.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a recuperator in a radiant tube heating device that performs heat exchange between combustion exhaust gas flowing through a radiant tube and combustion air used to combust a burner used in the radiant tube. [Background technology]

[0002] As a recuperator for a radiant tube type heating device, a configuration in which a double pipe is provided on the exhaust side of a radiant tube has been disclosed, as shown in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-146118 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-124050 [Patent Document 3] JP 2018-17470 A [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-205644 [Patent Document 5] Japanese Patent Application Laid-Open No. 2013-194977 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-described configuration, the area where the combustion air is preheated using the heat from the exhaust gas is limited to the outer circumferential surface of the outer tube of the double-walled pipe. Therefore, in order to increase the heat transfer area, a configuration is disclosed in which spiral, linear, or wavy fins are provided on the outer circumferential surface of the outer tube, as shown in Patent Document 2. However, the heat received by the fins is mainly transferred to the inside of the outer tube at the line contact portion where the fins are joined to the outer tube.

[0005] To increase the area of ​​contact, a configuration has been disclosed in which a spiral flow path is formed on the outer circumferential surface of the double pipe, and heat is transferred from the front and back surfaces, as shown in Patent Documents 3 to 5. However, even when such a flow path is formed on the outer circumferential surface of the outer pipe, there is a problem in that the fluid in the flow path flows too smoothly, resulting in insufficient heat exchange.

[0006] Therefore, the object of the present invention is to provide a recuperator that has improved heat exchange function between the combustion exhaust gas flowing through the radiant tube and the combustion air used to burn the burner used in the radiant tube. [Means for solving the problem]

[0007] The present invention is a recuperator that performs heat exchange between combustion exhaust gas flowing through a radiant tube and combustion air used to combust a burner used in the radiant tube, The recuperator has an outer surface formed with a plurality of grooves extending in a zigzag pattern in the longitudinal direction of the recuperator.

[0008] According to the above configuration, the recuperator has a plurality of grooves extending in a zigzag pattern in the longitudinal direction on its outer surface, and the combustion exhaust gas, which is a fluid flowing through the grooves, collides with the heat transfer surface due to the zigzag shape of the grooves, thereby achieving sufficient heat exchange between the combustion exhaust gas and the combustion air flowing inside the recuperator, thereby improving the heat exchange function of the recuperator. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a recuperator with an improved heat exchange function between the combustion exhaust gas and the combustion air. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a radiant tube heating device including a recuperator according to an embodiment of the present invention. FIG. [Figure 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view taken along the arrows BB in FIG. 2. [Figure 4] FIG. 2 is a side view of the recuperator. [Figure 5] FIG. 4 is a cross-sectional view taken along the arrow CC in FIG. 3. [Figure 6] FIG. 2 is a perspective view of a portion of the body of the recuperator. [Figure 7] 10 is a schematic diagram of a protrusion according to another embodiment of the present invention. FIG. [Figure 8] 10 is a schematic diagram of a protrusion according to another embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Figure 1 is a schematic diagram of a radiant tube heating apparatus 10 equipped with a recuperator according to an embodiment of the present invention. As shown in Figure 1, the radiant tube heating apparatus 10 includes a cylindrical radiant tube 1, which is heated from the inside, and the material to be treated placed in the furnace is heated by radiant heat from the outer surface of the radiant tube 1.

[0012] In the radiant tube heating device 10 of this embodiment, a U-shaped radiant tube 1 is used, and the main body 11 of the U-shaped radiant tube is placed inside the furnace. Both ends of the radiant tube 1 extend outside the furnace through the furnace wall. Note that the radiant tube 1 is not limited to a U-shape, and may have a W-shape, I-shape, or other shape.

[0013] A burner 2 that burns fuel gas, such as hydrocarbon gas, with combustion air is inserted into one end of the radiant tube 1. The burner 2 generates high-temperature combustion exhaust gas by burning the fuel gas using the combustion air, and the combustion exhaust gas flowing through the radiant tube 1 is used to heat the radiant tube 1 from the inside. The temperature of this combustion exhaust gas is preferably 800°C or higher and 1400°C or lower, and more preferably 900°C or higher and 1300°C or lower.

[0014] A recuperator 3 is inserted into the other end of the radiant tube 1. The recuperator 3 heats the combustion air supplied from outside by performing heat exchange between the combustion exhaust gas from the burner 2 flowing inside the radiant tube 1 and the combustion air introduced into the recuperator 3 through the combustion air inlet pipe 4. The combustion air heated by the recuperator 3 is supplied through the combustion air supply pipe 5 to one end of the radiant tube 1 where the burner 2 is provided. The combustion air supplied to one end of the radiant tube 1 is used for combustion in the burner 2, becoming high-temperature combustion exhaust gas which flows through the main body 11 of the radiant tube 1 and heads toward the recuperator 3.

[0015] The combustion exhaust gas that has exchanged heat with the combustion air in the recuperator 3 is discharged from an exhaust port 6.

[0016] FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG. 2. FIG. 4 is a side view of the recuperator 3, and FIG. 5 is a cross-sectional view taken along line CC in FIG. 3. For ease of explanation, the orientation of the exhaust port 6 in FIG. 3 is shown as being opposite to that in FIG. 1. As shown in FIGS. 2 to 5, the recuperator 3 includes a main body 31 and a tip end 32 connected to the main body 31. The main body 31 has a double-pipe structure including an outer pipe 311 and an inner pipe 312. While thinner wall thicknesses of the outer pipe 311 and the inner pipe 312 are preferable to improve heat exchange efficiency, in terms of the structural strength of the main body 31 of the recuperator 3, it is preferable that the wall thickness of the outer pipe 311 be 1 mm or more and that of the inner pipe 312 be 3 mm or more.

[0017] The tip portion 32 includes a hemispherical portion 33 located at the tip 38 of the recuperator 3 and a cylindrical portion 34 connected to the hemispherical portion 33. The cylindrical portion 34 has a double-pipe structure including an outer pipe 341 and an inner pipe 342.

[0018] The outer tube 311 of the main body 31 and the outer tube 341 of the cylindrical portion 34 are connected to each other, and the inner tube 312 of the main body 31 is connected to the inner tube 342 of the cylindrical portion 34. Any method of connection or coupling may be used, such as welding, adhesive bonding, insertion, or screwing.

[0019] Fig. 6 is a perspective view of a portion of the recuperator body 31. As shown in Figs. 4 and 6, a plurality of grooves 7 extending in a zigzag pattern in the longitudinal direction of the recuperator 3 are formed on the outer surface of the outer tube 311 of the body 31. Each groove 7 extends in a zigzag pattern in the longitudinal direction of the recuperator, but none of the grooves 7 completes a full circumference in the circumferential direction of the recuperator 3. Specifically, each groove 7 extends in a zigzag pattern for less than half the circumference of the recuperator 3, and the entire groove 7 can be seen when viewed from a side surface centered on the center line of the groove 7 extending in the axial direction.

[0020] The groove portion 7 has a plurality of bent portions 71, and the bent portions 71 are bent in two stages. That is, the tips of the bent portions 71 are chamfered. More specifically, the two-stage bent shape is trapezoidal, and between the first bend 71a and the second bend 71b, the groove in that portion extends linearly parallel to the axial direction X of the recuperator 3. Furthermore, the width of the groove portion 7 is increased at the tip 72, so that the groove of the adjacent groove portion 7 is connected. Note that the amplitude of the bent portions 71 is preferably greater than the groove width of the groove portion 7.

[0021] The protrusions 8 forming the side surfaces of the grooves 7 are formed to protrude from the outer surface of the inner tube 312, with the tips 8a of the protrusions 8 positioned near the inner surface of the radiant tube 1. An opening 81 is formed inside the protrusions 8, penetrating the recuperator 3 in the axial direction. Heat exchange occurs between the combustion air passing through the openings 81 and the combustion exhaust gas passing through the grooves 7, heating the combustion air with the heat of the combustion exhaust gas. The grooves 7, which are the flow paths for the combustion exhaust gas, and the openings 81, which are the flow paths for the combustion air, are arranged alternately, extending in a zigzag pattern in the axial direction of the recuperator 3. As shown in FIG. 5, the rear end 39 of the recuperator 3 is closed by a flange 9, which has a hole 36a leading to the central flow path 36 and an inlet 81a leading to the openings 81.

[0022] The main body 31 of the recuperator 3 is configured by joining a plurality of segments 31a that are divided in the longitudinal direction. The bent portion 71 is located at the joint 31b of the segments 31a. That is, the segments 31a are joined at the trapezoidal upper base portion of the bent portion 71 (the portion extending parallel to the axial direction of the recuperator 3).

[0023] The segments 31a and tip 32 of the main body 31 of the recuperator 3 are each manufactured using a 3D printer using ceramic powder. Examples of ceramics include silicon carbide (SiC), alumina, mullite, silicon nitride, and aluminum nitride. However, when used in a high-temperature furnace, silicon carbide is particularly preferable because of its excellent heat resistance, thermal shock resistance, and high thermal conductivity. The main body 31 is manufactured using a 3D printer and joined together, and the tip 32 is then joined to the main body 31 to form the recuperator 3. An adhesive or the like is used to join the segments 31a together and to join the main body 31 and the tip 32. The recuperator 3 may also be manufactured as a single unit without joining the segments 31a together.

[0024] 3, an eductor 35 that improves the suction of combustion air into the inner pipe of the recuperator 3 is provided in the inner pipe 342 of the cylindrical portion 34. The eductor 35 is formed in the inner pipe 342 of the cylindrical portion 34, and includes an injector 343 that protrudes inward from the inner surface of the inner pipe 342 so that the central flow passage 36 in the inner space of the inner pipe 342 narrows in diameter toward the main body portion 31, and a narrowing portion 315 that curves inward around the entire circumferential direction in the vicinity of the cylindrical portion 34 within the inner pipe 312 of the main body portion 31.

[0025] According to the above configuration, by providing the injector 343 on the inner surface of the inner pipe 342, the flow rate of the combustion air entering the inner pipe 342 is increased, generating negative pressure. As a result, the suction of the combustion exhaust gas into the inner pipe 342 can be promoted. Furthermore, by providing the reduced diameter section 315 in the inner pipe 312 of the main body 31, the suction of the combustion air into the inner pipe 312 is promoted, increasing the flow rate from the inner pipe 312 toward the combustion air supply pipe, thereby improving the efficiency of heat exchange. That is, by providing the eductor 35 in the inner pipe 342 of the cylindrical section 34 and the inner pipe 312 of the main body 31, the suction of the combustion air into the inner pipe 342 is promoted, and the flow rate of the combustion air flowing through the opening 81 is increased, thereby improving the efficiency of heat exchange (theoretically, the faster the fluid flow rate, the better the heat conduction).

[0026] (Flow of combustion air and combustion exhaust gas in radiant tube heating equipment) Combustion air introduced through the combustion air introduction pipe 4 is led from an inlet 81a opening in the flange 9 to an opening 81 in the protrusion 8 inside the recuperator 3. The combustion air flowing through the opening 81 of the recuperator 3 is heated by heat exchange with the combustion exhaust gas generated by combustion in the burner 2 and flowing through the groove 7 between the outer tube 311 of the recuperator 3 and the radiant tube 1.

[0027] The combustion air flowing through the openings 81 and the combustion exhaust gas flowing through the grooves 7 flow in opposite directions (counterflows), and they flow side by side in a zigzag pattern, colliding with the heat transfer surface as they go. As a result, heat exchange between the combustion air and the combustion exhaust gas is promoted (theoretically, counterflows provide better heat conduction than parallel flows, and having the fluid collide with a heat transfer plate provides better heat conduction than having the fluid run along the heat transfer plate).

[0028] The combustion exhaust gas that has heated the combustion air in the recuperator 3 flows through the groove 7 to the rear end 39 of the recuperator 3 , where it strikes the flange 9 , changes direction, and is discharged from the exhaust port 6 .

[0029] The combustion air heated by the combustion exhaust gas flows from the opening 81 at the tip 32 of the recuperator 3, passes through the space 37 between the outer tube 341 and the inner tube 342 of the cylindrical portion 34, turns around inside the hemispherical portion 33, and enters the central flow path 36 inside the inner tube 342 of the cylindrical portion 34. The combustion air that has entered the inner tube 342 of the cylindrical portion 34 then enters the inner tube 312 of the main body 31.

[0030] Combustion air flowing inside the inner pipe 312 of the main body 31 is supplied to one end of the radiant tube 1, on which the burner 2 is installed, through the combustion air supply pipe 5. The burner 2 burns the fuel gas with the combustion air supplied from the combustion air supply pipe 5, generating new combustion exhaust gas.

[0031] The combustion exhaust gas generated by the combustion of fuel air by the burner 2 heats the radiant tube 1 from the inside, and the radiant heat from the outer surface of the radiant tube 1 heats the material to be treated placed in a furnace equipped with a radiant tube type heating device 10.

[0032] The radiant tube type heating device 10 having the above-described configuration can achieve the following effects.

[0033] (1) The recuperator 3 has a plurality of grooves 7 extending in a zigzag pattern in the longitudinal direction on its outer surface. The zigzag shape of the grooves 7 causes the combustion exhaust gas, which is a fluid flowing through the grooves 7, to collide with the heat transfer surface as it flows, ensuring sufficient heat exchange between the combustion exhaust gas and the combustion air flowing inside the recuperator. As a result, the heat exchange function of the recuperator 3 can be improved.

[0034] (2) The bent portion 71 has a two-stage bent shape, which increases the number of collisions with the heat transfer surface and allows the bending angle at each stage to be reduced. As a result, heat exchange is further promoted and the flow of combustion exhaust gas in the groove portion 7 is made smoother.

[0035] (3) The groove width of the groove portion 7 is increased at the tip, which makes it easier for the fuel exhaust gas to enter the groove portion 7 from the tip of the groove portion 7, thereby smoothing the flow of the fuel exhaust gas in the groove portion 7.

[0036] (4) The inner tube is formed with an injector having an inner tube protrusion that protrudes inward from the inner surface of the inner tube to improve the suction force of the fluid into the inner tube, thereby increasing the flow rate of the combustion air entering the inner tube. As a result, the suction of the combustion exhaust gas into the inner tube is promoted, and by increasing the flow rate of the combustion air flowing through the opening 81, the efficiency of heat exchange can be improved.

[0037] (5) The recuperator 3 has a double-pipe structure consisting of an outer pipe and an inner pipe, and the depth of the grooves formed in the outer pipe extends to the vicinity of the inner pipe, increasing the flow rate of the exhaust fuel gas flowing through the grooves 7. As a result, heat exchange between the exhaust fuel gas and the combustion air can be performed more effectively.

[0038] (6) The protrusion 8 forming the groove portion 7 is formed so as to protrude from the outer surface of the inner tube 312, and the tip of the protrusion 8 is located near the inner surface of the radiant tube 1, so that the amount of combustion exhaust gas that does not flow through the groove portion 7 can be reduced, and heat exchange between the combustion exhaust gas flowing through the groove portion 7 and the combustion air flowing through the opening 81 of the protrusion 8 can be more effectively carried out.

[0039] (7) The recuperator 3 is constructed by joining a plurality of segments that are divided in the longitudinal direction, which improves the manufacturability of the recuperator 3. Furthermore, by arranging a bending portion having a two-stage bending shape at the joint of the segments, it becomes easy to align the grooves (because the segments are joined at a portion extending parallel to the axial direction of the recuperator 3), and the segments can be joined easily. Furthermore, by using segments, the length of the parts is shortened, which makes handling easier and reduces the possibility of damage to the parts.

[0040] (8) The recuperator 3 is manufactured using a 3D printer with ceramic powder as the material, so that the recuperator 3 having the groove portion 7 can be easily manufactured. In addition, by using SiC powder, which has particularly high heat resistance, as the material, the recuperator 3 can be used even in a high-temperature furnace.

[0041] In the above embodiment, the inner and outer surfaces of the protrusions 8 are flat, but the shape of the inner and / or outer surfaces may be changed to increase the contact area between the combustion air and the combustion exhaust gas. Fig. 7 is a schematic diagram of a protrusion in another embodiment in which the inner surface of the protrusions 8 is wavy, and Fig. 8 is a schematic diagram of a protrusion in yet another embodiment in which fins are provided on the inner and outer surfaces of the protrusions.

[0042] As shown in Figures 7 and 8, the inner surface 8b and / or the outer surface 8c of the protrusion 8 may be corrugated to increase the contact area between the combustion air and the combustion exhaust gas, and fins 82 may be provided on the inner surface 8b and / or the outer surface 8c of the protrusion 8.

[0043] The above-described other embodiment can provide the following effects.

[0044] The inner surface 8b and / or the outer surface 8c of the protrusion 8 that forms the groove 7 is wavy, which increases the contact area between the combustion exhaust gas and the combustion air, thereby improving the heat exchange function of the recuperator 3.

[0045] Fins 82 are provided on the inner surface 8b and / or outer surface 8c of the protrusion 8 that forms the groove 7, increasing the contact area between the combustion exhaust gas and the combustion air, thereby improving the heat exchange function of the recuperator 3.

[0046] Also, unlike the above embodiment, an opening (not shown) may be provided at the tip 32 of the recuperator 3 so that part of the fuel exhaust gas is introduced into the recuperator 3 from the tip 32 of the recuperator 3.

[0047] In the recuperator 3, when the combustion air is heated (preheated) to a high temperature by the heat of the combustion exhaust gas and then introduced from the combustion air supply pipe 5 to the burner 2 to burn the fuel gas, the energy saving effect is improved, but the combustion temperature becomes too high during combustion, increasing the amount of NOx generated during combustion, and combustion exhaust gas containing a large amount of NOx is exhausted from the exhaust port 6 at the other end of the radiant tube 1.

[0048] In contrast, if the combustion air is mixed with a portion of the combustion exhaust gas in the recuperator 3 and the combustion exhaust gas is introduced together with the heated combustion air through the combustion air supply pipe 5 to the burner 2 to combust the fuel gas, the oxygen concentration of the combustion air decreases, slowing the combustion rate in the burner 2. As a result, the combustion temperature during combustion is prevented from becoming too high, and the amount of NOx generated during combustion can be reduced. Note that the higher the temperature of the combustion air heated by the combustion exhaust gas, the more preferably the amount of combustion exhaust gas mixed with the heated combustion air.

[0049] The present invention and embodiments can be summarized as follows.

[0050] (1) One embodiment of the present invention is a recuperator that performs heat exchange between combustion exhaust gas flowing through a radiant tube and combustion air used to combust a burner used in the radiant tube, The recuperator has an outer surface formed with a plurality of grooves extending in a zigzag pattern in the longitudinal direction of the recuperator.

[0051] According to the above configuration (1), since a plurality of grooves extending in a zigzag shape in the longitudinal direction are formed on the outer surface of the recuperator, the combustion exhaust gas, which is a fluid flowing in the grooves, collides with the heat transfer surface due to the zigzag shape of the grooves, thereby ensuring sufficient heat exchange between the combustion exhaust gas and the combustion air flowing inside the recuperator, thereby improving the heat exchange function of the recuperator.

[0052] (2) In the configuration (1), the groove portion has a plurality of bent portions, The bent portion has a two-stage bent shape.

[0053] According to the configuration (2), by forming the bent portion into a two-stage bending shape, the number of collisions with the heat transfer surface can be increased and the bending angle at each stage can be reduced. As a result, heat exchange is further promoted, and the flow of combustion exhaust gas through the groove portion can be made smoother.

[0054] (3) In the above configuration (1) or (2), the groove portion has a width that is increased at the tip.

[0055] According to the configuration (3), the fuel exhaust gas can easily enter the grooves from the tips of the grooves, thereby smoothing the flow of the fuel exhaust gas in the grooves.

[0056] (4) In any one of the above configurations (1) to (3), the inner and / or outer surfaces of the protrusions that form the grooves are wavy.

[0057] According to the above configuration (4), the contact area between the combustion exhaust gas and the combustion air increases, so that the heat exchange function of the recuperator can be improved.

[0058] (5) In any one of the above configurations (1) to (3), fins are provided on the inner and / or outer surfaces of the protrusions that form the grooves.

[0059] According to the configuration (5), the contact area between the combustion exhaust gas and the combustion air increases, so that the heat exchange function of the recuperator can be improved.

[0060] (6) In any one of the above configurations (1) to (5), the recuperator has a double-pipe structure of an outer pipe and an inner pipe, The inner pipe is formed with an injector having an inner pipe protrusion that protrudes inward from the inner surface of the inner pipe to improve the force of suction of the fluid into the inner pipe.

[0061] According to the configuration (6), by forming an injector in the inner pipe, the flow rate of the combustion air entering the inner pipe can be increased, and as a result, the suction of the combustion exhaust gas into the inner pipe is promoted, and by increasing the flow rate of the combustion air flowing through the opening 81, the efficiency of heat exchange can be improved.

[0062] (7) In any one of the above configurations (1) to (6), the recuperator has a double-pipe structure of an outer pipe and an inner pipe, The depth of the groove formed in the outer tube extends to the vicinity of the inner tube.

[0063] According to the above configuration (7), the flow rate of the exhaust fuel gas flowing through the groove portion increases, so that heat exchange between the exhaust fuel gas and the combustion air can be more effectively performed.

[0064] (8) In the above configuration (7), the protrusion forming the groove is formed so as to protrude from the outer surface of the inner tube, and the tip of the protrusion is located near the inner surface of the radiant tube.

[0065] According to the above configuration (8), the amount of combustion exhaust gas that does not flow through the groove portion can be reduced, and heat exchange between the combustion exhaust gas flowing through the groove portion and the combustion air flowing through the opening of the protrusion portion can be more effectively performed.

[0066] (9) In the configuration (2), the recuperator is configured by joining a plurality of divided bodies divided in the longitudinal direction, The bent portion is located at the joint of the divided body.

[0067] According to the above-mentioned configuration (9), the recuperator is constructed by joining the divided bodies, which improves the manufacturability of the recuperator. Furthermore, by arranging a bent portion having a two-stage bent shape at the joint of the divided bodies, it becomes easy to align the grooves, and the divided bodies can be joined easily. Furthermore, by using divided bodies, the length of the parts is shortened, which makes handling easier and reduces the possibility of damage to the parts.

[0068] (10) In any one of the above configurations (1) to (9), the recuperator is manufactured using a 3D printer and ceramic powder as a material.

[0069] According to the above configuration (10), a recuperator having a groove can be easily manufactured.

[0070] (11) In the above configuration (10), the ceramic powder is SiC powder.

[0071] According to the above configuration (11), by using SiC powder, which has particularly high heat resistance, as the ceramic powder, the recuperator can be used even in a high-temperature furnace.

[0072] Various modifications and variations may be made without departing from the spirit and scope of the present invention as set forth in the following claims. [Industrial Applicability]

[0073] The present invention can provide a recuperator with an improved heat exchange function between the combustion exhaust gas and the combustion air, and is therefore of great industrial utility. [Explanation of symbols]

[0074] 1 Radiant tube 11 Main body 2 Burner 3 Recuperator 31 Main body 31a Split body 31b Joint part 311 Outer tube 312 Inner tube 313 Heat exchange member 314 Reduced diameter portion 315 Reduced diameter section 32 Tip 33 Hemisphere 34 Cylindrical part 341 Outer tube 342 Inner tube 343 Injector 35 Eductor 36 Central channel 36a hole 37 Space 38 Tip 39 Rear end 4 Combustion air intake pipe 5 Combustion air supply pipe 6 exhaust port 7 Groove 71 Bend 71a Bending 71b Bending 72 Tip 8 Protrusion 8a tip 8b Inside surface 8c Outside surface 81 Opening 81a Inlet 82 Finn 9 flange 10 Radiant tube heating device

Claims

1. A recuperator that performs heat exchange between combustion exhaust gas flowing through a radiant tube and combustion air used to combust a burner used in the radiant tube, A recuperator, wherein a plurality of grooves extending in a zigzag pattern in the longitudinal direction of the recuperator are formed on an outer surface of the recuperator.

2. The groove portion has a plurality of bent portions, The recuperator according to claim 1 , wherein the bent portion has a two-stage bent shape.

3. The recuperator according to claim 1 , wherein the groove portion has a width that increases at a tip end thereof.

4. 2. The recuperator according to claim 1, wherein the inner and / or outer surfaces of the protrusions forming the grooves are wavy.

5. 2. The recuperator according to claim 1, wherein fins are provided on the inner and / or outer surfaces of the protrusions that form the grooves.

6. The recuperator has a double-pipe structure consisting of an outer pipe and an inner pipe, 2. The recuperator according to claim 1, wherein the inner tube is formed with an injector having an inner tube protrusion protruding inward from the inner surface of the inner tube to improve the suction force of the fluid into the inner tube.

7. The recuperator has a double-pipe structure consisting of an outer pipe and an inner pipe, 2. The recuperator according to claim 1, wherein the depth of the groove formed in said outer tube extends to the vicinity of said inner tube.

8. 8. The recuperator according to claim 7, wherein the protrusion forming the groove is formed so as to protrude from the outer surface of the inner tube, and the tip of the protrusion is located near the inner surface of the radiant tube.

9. The recuperator is configured by joining a plurality of divided bodies divided in the longitudinal direction, 3. The recuperator according to claim 2, wherein the bent portion is located at a joint of the divided bodies.

10. The recuperator according to any one of claims 1 to 9, wherein the recuperator is manufactured using a 3D printer using ceramic powder as a material.

11. 11. The recuperator of claim 10, wherein the ceramic powder is SiC powder.

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