Exhaust heat recovery device

Abstract

Provided is an exhaust heat recovery device that prevents damage to joints caused by thermal stress generated by the temperature difference in a heat transfer tube group. 【Solution means】An exhaust heat recovery device 1 that includes a heat transfer tube group 20 through which a heated fluid 5 flows inside a flow passage 10 through which exhaust gas 3 flows, a support member 30 that supports an end portion 22 of the heat transfer tube group 20, a joint portion 25 that joins and fixes the end portion 22 of the heat transfer tube group 20 to the support member 30, and expansion joints 17 and 45 that displaceably connect the support member 30 to which the heat transfer tube group 20 is joined and fixed by the joint portion 25.

Description

Technical Field

[0001] This invention relates to an exhaust heat recovery device (recuperator).

Background Art

[0002] In heat equipment such as a heating furnace, an exhaust heat recovery device that heats a fluid to be heated by using the exhaust heat generated from the heating furnace or the like is used. The exhaust heat recovery device can improve the energy efficiency of the heat equipment by heating a heat transfer tube group through which the fluid to be heated flows with the heat of the exhaust gas and performing heat exchange.

[0003] Patent Document 1 and Patent Document 2 disclose an exhaust heat recovery device in which a heat transfer tube group is disposed inside a flow passage through which exhaust gas flows.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The heat transfer tube group is joined and fixed to the support member by joints formed by, for example, welding. In the above prior art, when heat exchange is performed, there is a problem that the joints are likely to be damaged due to thermal stress generated by the temperature difference in the heat transfer tube group heated to a high temperature.

[0006] Therefore, an object of this invention is to provide an exhaust heat recovery device that prevents damage to the joints caused by thermal stress generated by the temperature difference of the heat transfer tube group.

Means for Solving the Problems

[0007] To solve the above problems, an exhaust heat recovery device according to an aspect of the present invention includes: a heat transfer tube group through which a fluid to be heated flows, provided inside a flow passage through which exhaust gas flows, the exhaust heat recovery device being: a support member that supports an end portion of the heat transfer tube group; a joint portion that joins and fixes the end portion of the heat transfer tube group to the support member; and a telescopic joint that displaceably connects the support member to which the heat transfer tube group is joined and fixed by the joint portion.

Advantages of the Invention

[0008] According to the present invention, the telescopic joint absorbs the thermal stress generated due to the temperature difference of the heat transfer tube group in the heat transfer tube group joined and fixed to the support member by the joint portion, so that damage to the joint portion can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the exhaust heat recovery device 1 according to the present invention will be described with reference to the drawings.

[0011] 〔First Embodiment〕 Referring to FIGS. 1 and 2, the waste heat recovery device 1 according to the first embodiment will be described. FIG. 1 is a diagram schematically illustrating the waste heat recovery device 1 according to the first embodiment. FIG. 2 is a diagram schematically illustrating part A in the waste heat recovery device 1 shown in FIG. 1.

[0012] As shown in FIG. 1, the waste heat recovery device 1 includes a heat transfer tube group 20 through which a heated fluid 5 flows, inside a flow passage 10 through which exhaust gas 3 flows.

[0013] The flow passage 10 includes a housing 11 having a circular or rectangular cross-section, an inlet portion 12 through which the exhaust gas 3 flows in, an outlet portion 14 through which the exhaust gas 3 flows out, and a plurality of mounting openings 15 provided in the housing 11. The flow passage 10 is, for example, a flue extending in the horizontal direction as the longitudinal direction. For example, exhaust gas 3 at 1200°C and 0.2 MPa flows inside the flow passage 10. The flow passage 10 is installed on the floor surface or overhead via a base or support columns (not shown). Also, the inner surface of the flow passage 10 is covered with a heat insulating material.

[0014] The waste heat recovery device 1 has a first expansion joint 17, an introduction pipe 43, a support member 30, a heat transfer tube group 20, a joint portion 25, a second expansion joint 45, a connection duct 50, and a discharge pipe 47. In the waste heat recovery device 1 shown in FIG. 1, the introduction pipe 43, the support member 30, the heat transfer tube group 20, the support member 30, the connection duct 50 located below, the support member 30, the heat transfer tube group 20, the support member 30, the connection duct 50 located above, the support member 30, the heat transfer tube group 20, the support member 30, the connection duct 50 located below, the support member 30, the heat transfer tube group 20, the support member 30, and the discharge pipe 47 communicate in this order.

[0015] The introduction pipe 43 is located on the downstream side of the flow passage 10, and the discharge pipe 47 is located on the upstream side of the flow passage 10. The heated fluid 5 introduced from the introduction pipe 43 flows sequentially through the support member 30, the heat transfer tube group 20, the connection duct 50, etc., and then is discharged from the discharge pipe 47, but is heated by receiving waste heat from the exhaust gas 3 during the process of flowing through the heat transfer tube group 20. The heated fluid 5 is, for example, combustion air or combustion gas used for a burner.

[0016] The connecting duct 50 is disposed outside the flow passage 10. By being in contact with the outside air, the thermal stress generated due to the temperature difference of the connecting duct 50 when the connecting duct 50 comes into contact with the high-temperature exhaust gas 3 can be reduced. The connecting duct 50 located above is supported by the duct support 52, and the connecting duct 50 located below is supported by the duct support leg 54.

[0017] The heat transfer tube group 20 extends in a direction (for example, the vertical direction) intersecting the longitudinal direction of the flow passage 10. In the heat transfer tube group 20, a plurality of heat transfer tubes forming a group are arranged in multiple stages and multiple rows in a spaced-apart state from each other. The heat transfer tubes are made of, for example, steel pipes with a circular cross-section. A gap through which the exhaust gas 3 flows is formed between the plurality of heat transfer tubes, and the exhaust heat from the exhaust gas 3 can be efficiently received.

[0018] The support member 30 is a member that supports each of the end portions 22 in the plurality of heat transfer tube groups 20, and is a so-called header (manifold). The end portion 22 of the heat transfer tube group 20 protrudes into the support member 30 and is joined and fixed to the support member 30 by the joint portion 25. The joint portion 25 is a welded portion formed by welding, for example. Since the heat transfer tube group 20 is firmly fixed to the support member 30 by the joint portion 25, a structure for absorbing the elongation due to the thermal expansion of the heat transfer tube group 20 is required.

[0019] A first expansion joint 17 is attached to the attachment opening 15 provided in the housing 11, and the support member 30 is connected to the first expansion joint 17. In other words, the first expansion joint 17 is interposed between the housing 11 and the support member 30 of the flow passage 10. The first expansion joint 17 has a function of displaceably connecting the support member 30 to which the heat transfer tube group 20 is joined and fixed by the joint portion 25 to the flow passage 10. By interposing the first expansion joint 17 between the flow passage 10 and the support member 30, displacement of the support member 30 with respect to the flow passage 10 is enabled.

[0020] As shown in FIG. 2, the first expansion joint 17 is, for example, a bellows-type metal expansion joint, and is made of, for example, 18-8 stainless steel. Thereby, even in an environment where the high-temperature exhaust gas 3 flows through the flow passage 10, the expansion and contraction movement of the first expansion joint 17 can be achieved without causing damage to the first expansion joint 17.

[0021] A second expansion joint 45 is interposed between the connecting duct 50 located above and the support member 30. Also, a second expansion joint 45 is interposed between the connecting duct 50 located below and the support member 30. The second expansion joint 45 has a function of displaceably connecting the support member 30 to which the heat transfer tube group 20 is joined and fixed by the joint portion 25 to the connecting duct 50. By interposing the second expansion joint 45 between the connecting duct 50 and the support member 30, displacement of the support member 30 with respect to the connecting duct 50 is enabled.

[0022] As shown in FIG. 2, the second expansion joint 45 is, for example, a bellows-type metal expansion joint, and is made of, for example, 18-8 stainless steel. Thereby, even in an environment where the high-temperature fluid to be heated 5 flows through the connecting duct 50, the expansion and contraction movement of the second expansion joint 45 can be achieved without causing damage to the second expansion joint 45.

[0023] Therefore, according to the above configuration, due to the expansion joints 17 and 45, in the heat transfer tube group 20 joined and fixed to the support member 30 by the joint portion 25, the thermal stress generated due to the temperature difference of the heat transfer tube group 20 and the thermal expansion in the flow direction of the exhaust gas 3 in the connecting duct 50 are absorbed, so that damage to the joint portion 25 can be suppressed.

[0024] 〔Second Embodiment〕 The exhaust heat recovery device 1 according to the second embodiment will be described with reference to FIG. 3. FIG. 3 is a diagram schematically explaining the main part of the exhaust heat recovery device 1 according to the second embodiment. Since the basic configuration is the same as that of the first embodiment, the differences from the above-described first embodiment will be described.

[0025] As shown in FIG. 3, the exhaust heat recovery device 1 according to the second embodiment is characterized in that, as the first expansion joint 17 and the second expansion joint 45, for example, a fabric-type non-metallic expansion joint 41 is provided.

[0026] The fabric-type non-metallic expansion joint 41 is, for example, a thick woven fabric obtained by thermocompression bonding a Teflon (registered trademark) sheet to an inorganic fiber cloth and integrating them, and has flexibility. Although the fabric-type non-metallic expansion joint 41 has inferior heat resistance compared to the bellows-type metallic expansion joint, it can be sufficiently used in an environment where the temperature of the exhaust gas 3 is not too high, and has the advantage that it is easy to create a desired shape due to its high flexibility. Thereby, the expansion joints 17 and 45 can be constructed at low cost.

[0027] It is not preferable that the fabric-type non-metallic expansion joint 41 is exposed to the radiant heat from the high-temperature exhaust gas 3 flowing through the flow passage 10 or the heat transfer tube group 20 through which the heated fluid 5 flows. Therefore, the inner surface of the fabric-type non-metallic expansion joint 41 is covered with a heat insulating material (not shown). Alternatively, a labyrinth 42 made of a heat-resistant material (for example, metallic) is circumferentially provided inside the fabric-type non-metallic expansion joint 41. The labyrinth 42 has a labyrinth structure with minute gaps and is configured to slide in the length direction L of the heat transfer tube group 20. The labyrinth 42 provided inside the fabric-type non-metallic expansion joint 41 serves as a heat shielding member that shields heat from the fabric-type non-metallic expansion joint 41. Thereby, it is possible to reduce the fabric-type non-metallic expansion joint 41 from receiving heat damage.

[0028] 〔Third Embodiment〕 The exhaust heat recovery device 1 according to the third embodiment will be described with reference to FIG. 4. FIG. 4 is a diagram schematically illustrating the slide support structure 70 in the exhaust heat recovery device 1 according to the third embodiment.

[0029] The waste heat recovery device 1 according to the third embodiment has a structure that can be commonly adopted for the first expansion joint 17 or the second expansion joint 45, and includes a slide support structure 70 shown in FIG. 4. Here, when a long expansion section is required, the expansion joints 17 and 45 are shown in a state where two are connected vertically via a stroke restricting plate 75 with a hole 81 in the center. Since it is long, the stroke restricting plate 75 is relayed and connected so that it does not buckle or twist in the middle. The first restricting rod 76 and the second restricting rod are used to maintain its self - standing in the structure as described below and guarantee a linear operation. The slide support structure 70 has a function of slidably supporting the support member 30 so that the support member 30 is displaced in the length direction L of the heat transfer tube group 20 when the heat transfer tube group 20 thermally expands. The slide support structure 70 is disposed outside so as to surround the expansion joints 17 and 45, that is, the first expansion joint 17 or the second expansion joint 45.

[0030] The slide support structure 70 includes a first side flange 71, a second side flange 72, a guide rod 73, a guide cylinder 74, a stroke restricting portion 75, a first restricting rod 76, a second restricting rod 77, and a heat insulation cover 78. In the case of the first expansion joint 17, for example, the first side flange 71 is attached to the housing 11 of the flow passage 10, and the second side flange 72 is attached to the support member 30. In the case of the second expansion joint 45, for example, the first side flange 71 is attached to the connecting duct 50, and the second side flange 72 is attached to the support member 30. There is a hole 81 in the center of the first side flange 71 and the second side flange 72, similar to the above - mentioned stroke restricting plate 75. When adopted in the first expansion joint 17, the heat transfer tube group 20 passes through it, and when adopted in the second expansion joint 45, the heated fluid 5 flows through it.

[0031] A guide rod 73 is erected on the first side flange 71, and a guide cylinder 74 is erected on the second side flange 72. The guide rod 73 and the guide cylinder 74 extend in the length direction L of the heat transfer tube group 20. The resin portion located at the tip of the guide rod 73 is inserted into the guide cylinder 74 and is configured to slide in the length direction L of the heat transfer tube group 20. By making the tip of the guide rod 73 made of resin in this way, the sliding with the guide cylinder 74 becomes easy.

[0032] At the central outer peripheries of the first telescopic joint 17 and the second telescopic joint 45, a stroke restricting portion 75 projecting outward is attached. To the stroke restricting portion 75, a first restricting rod 76 provided on one side flange 71 and extending toward the other side flange 72, and a second restricting rod 77 provided on the other side flange 72 and extending toward the one side flange 71 are provided. Stoppers 79 are provided at the tip ends of the first restricting rod 76 and the second restricting rod 77. The telescopic joints 17, 45 shown in FIG. 4 are in an extended state, and are restricted from further extending by the stoppers 79 provided on the respective first restricting rod 76 and second restricting rod 77 coming into contact with the stroke restricting portion 75. When the telescopic joints 17, 45 are in a contracted state, the stoppers 79 are separated from the stroke restricting plate 75.

[0033] A heat insulating cover 78 is attached to the inner portion of the guide cylinder 74 so as to face the stroke restricting plate 75. The heat insulating cover 78 is made of, for example, metal, and has a function of shielding radiant heat from the telescopic joints 17, 45 and protecting the guide rod 73 and the guide cylinder 74.

[0034] Therefore, by providing the slide support structure 70, when the heat transfer tube group 20 thermally expands, the support member 30 can smoothly displace in the length direction L of the heat transfer tube group 20. Further, since the long telescopic joints 17, 45 can always expand and contract linearly, they are less likely to be damaged even when repeatedly expanded and contracted.

[0035] Although specific embodiments and numerical values of the present invention have been described, the present invention is not limited to the above embodiments, and various modifications can be made and implemented within the scope of the present invention.

[0036] In the above-described embodiment, the same type of expansion joint is used for the first expansion joint 17 and the second expansion joint 45, but different types of expansion joints can be used for the first expansion joint 17 and the second expansion joint 45. That is, a bellows-type metal expansion joint having heat resistance can be used for the first expansion joint 17, and a fabric-type non-metal expansion joint that enables low cost can be used for the second expansion joint 45.

[0037] As an example of the joining method of the heat transfer tube group 20 to the support member 30, welding was illustrated, but brazing, screw fixing, etc. can also be used.

[0038] Summarizing this invention and the embodiment, it is as follows.

[0039] The waste heat recovery device 1 according to one aspect of this invention is a waste heat recovery device 1 provided with a heat transfer tube group 20 through which a heated fluid 5 flows inside a flow passage 10 through which exhaust gas 3 flows, a support member 30 that supports an end portion 22 of the heat transfer tube group 20, a joint portion 25 that joins and fixes the end portion 22 of the heat transfer tube group 20 to the support member 30, and expansion joints 17, 45 that displaceably connect the support member 30 to which the heat transfer tube group 20 is joined and fixed by the joint portion 25, and is characterized by including these.

[0040] According to the above configuration, in the heat transfer tube group 20 joined and fixed to the support member 30 by the joint portion 25 by the expansion joints 17, 45, the thermal stress generated due to the temperature difference of the heat transfer tube group 20 is absorbed, so damage to the joint portion 25 can be suppressed.

[0041] Also, in the waste heat recovery device 1 of one embodiment, the expansion joint 17 is interposed between the flow passage 10 and the support member 30 so as to enable displacement of the support member 30 with respect to the flow passage 10.

[0042] According to the above embodiment, displacement of the support member 30 with respect to the flow passage 10 is enabled.

[0043] Also, in the exhaust heat recovery device 1 of one embodiment, it further includes a connecting duct 50 connected to the adjacent support members 30, the expansion joint 45 is interposed between the connecting duct 50 and the support member 30 so as to enable displacement of the support member 30 with respect to the connecting duct 50.

[0044] According to the above embodiment, displacement of the support member 30 with respect to the connecting duct 50 is enabled.

[0045] Also, in the exhaust heat recovery device 1 of one embodiment, the connecting duct 50 is disposed outside the flow passage 10.

[0046] According to the above embodiment, the thermal stress generated due to the temperature difference of the connecting duct 50 when the connecting duct 50 comes into contact with the high-temperature exhaust gas 3 can be reduced.

[0047] Also, in the exhaust heat recovery device 1 of one embodiment, the expansion joints 17, 45 are bellows-type metal expansion joints.

[0048] According to the above embodiment, even in an environment where the high-temperature exhaust gas 3 flows through the flow passage 10, displacement of the support member 30 can be enabled without causing damage to the expansion joints 17, 45.

[0049] Also, in the exhaust heat recovery device 1 of one embodiment, the expansion joints 17, 45 are fabric-type non-metal expansion joints.

[0050] According to the above embodiment, the expansion joints 17, 45 can be constructed at low cost.

[0051] Also, in the exhaust heat recovery device 1 of one embodiment, it further has a slide support structure 70 that slide-supports the support member 30 so that the support member 30 displaces in the longitudinal direction L of the heat transfer tube group 20.

[0052] According to the above embodiment, when the heat transfer tube group 20 thermally expands, the support member 30 can smoothly displace in the length direction L of the heat transfer tube group 20.

Explanation of Signs

[0053] 1…Exhaust heat recovery device (recuperator) 3…Exhaust gas 5…Fluid to be heated 10…Flow passage 11…Housing 12…Inlet portion 14…Outlet portion 15…Opening 17…First expansion joint (expansion joint) 20…Heat transfer tube group 22…End portion 25…Joint portion 30…Support member 41…Fabric-type non-metallic expansion joint 42…Labyrinth 43…Introduction pipe 45…Second expansion joint (expansion joint) 47…Discharge pipe 50…Connecting duct 52…Duct support 54…Duct support leg 70…Slide support structure 71…One-side flange 72…Other-side flange 73…Guide rod 74…Guide cylinder 75…Stroke regulating plate 76…First regulating rod 77…Second regulating rod 78…Heat insulation cover 79…Stopper 81…Hole L…Length direction

Claims

1. An exhaust heat recovery device comprising a group of heat transfer tubes through which a fluid to be heated flows, provided inside a flow passage through which exhaust gas flows, a support member that supports the ends of the group of heat transfer tubes, a joint portion that joins and fixes the ends of the group of heat transfer tubes to the support member, a telescopic joint that displaceably connects the support member to which the group of heat transfer tubes is joined and fixed by the joint portion, and a slide support structure that slidably supports the support member so that the support member is displaced in the longitudinal direction of the group of heat transfer tubes. The slide support structure includes a first side flange to which one end of the telescopic joint is attached, a second side flange to which the other end of the telescopic joint is attached, a guide rod erected on the first side flange, a guide cylinder erected on the second side flange through which the guide rod is inserted, and a stroke restricting portion attached to the central outer peripheral portion of the telescopic joint. The stroke restricting portion is provided with a first restricting rod provided on the first side flange and extending toward the second side flange, and a second restricting rod provided on the second side flange and extending toward the first side flange. Stoppers are provided at the tip ends of each of the first restricting rod and the second restricting rod, and the telescopic joint is restricted from further extending by the stoppers provided on each of the first restricting rod and the second restricting rod coming into contact with the stroke restricting portion. An exhaust heat recovery device.

2. The exhaust heat recovery device according to claim 1, wherein the telescopic joint is interposed between the flow passage and the support member so as to enable displacement of the support member with respect to the flow passage.

3. further comprising a connecting duct connected to adjacent support members, The exhaust heat recovery device according to claim 1, wherein the telescopic joint is interposed between the connecting duct and the support member so as to enable displacement of the support member with respect to the connecting duct.

4. The exhaust heat recovery device according to claim 3, wherein the connecting duct is disposed outside the flow passage.

5. The exhaust heat recovery device according to claim 1, wherein the telescopic joint is a bellows-type metal telescopic joint.

6. The exhaust heat recovery device according to claim 1, wherein the telescopic joint is a fabric-type non-metal telescopic joint.

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