Heat recovery system

Abstract

This invention provides a heat recovery device that prevents damage to joints caused by thermal stress resulting from temperature differences in a group of heat transfer tubes. [Solution] A heat recovery device 1 is provided which has a heat transfer tube group 20 through which a heated fluid 5 flows inside a flow passage 10 through which exhaust gas 3 flows, and comprises a support member 30 that supports the end 22 of the heat transfer tube group 20, a joint 25 that joins and fixes the end 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 25.

Description

Technical Field

[0006] , , ,

[0005] , , ,

[0007] , , , ,

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

Background Art

[0002] In thermal equipment such as a heating furnace, an exhaust heat recovery device that heats a fluid to be heated by using exhaust heat generated from the heating furnace or the like is used. The exhaust heat recovery device can improve the energy efficiency of the thermal equipment by heating a heat transfer tube group through which the fluid to be heated flows with the heat of 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 a support member by a joint formed by, for example, welding. In the above prior art, when heat exchange is performed, there is a problem that the joint is 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 joint caused by thermal stress generated by the temperature difference in the heat transfer tube group.

Means for Solving the Problems

[0007] To solve the above problems, a waste heat recovery device according to one aspect of this invention is provided. A heat recovery device that includes a group of heat transfer tubes through which a heated fluid flows, located inside a flow passage through which exhaust gas flows, A support member that supports the end of the heat transfer tube group, A joint portion that joins and fixes the end of the heat transfer tube group to the support member, The present invention is characterized by comprising an expansion joint that allows displacement of the support member, to which the heat transfer tube group is joined and fixed by the aforementioned joint. [Effects of the Invention]

[0008] According to this invention, in a group of heat transfer tubes joined and fixed to a support member by an expansion joint, thermal stress caused by the temperature difference among the heat transfer tubes is absorbed, thereby suppressing damage to the joint. [Brief explanation of the drawing]

[0009] [Figure 1] This figure schematically illustrates a waste heat recovery device according to the first embodiment. [Figure 2] This figure schematically illustrates section A of the waste heat recovery device shown in Figure 1. [Figure 3] This figure schematically illustrates part A of the waste heat recovery device according to the second embodiment. [Figure 4] This figure schematically illustrates the slide support structure in the waste heat recovery device according to the third embodiment. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of the waste heat recovery device 1 according to this invention will be described with reference to the drawings.

[0011] [First Embodiment] The waste heat recovery device 1 according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram illustrating the waste heat recovery device 1 according to the first embodiment. Figure 2 is a schematic diagram illustrating part A in the waste heat recovery device 1 shown in Figure 1.

[0012] As shown in Figure 1, the waste heat recovery device 1 is equipped with a group of heat transfer tubes 20 through which the heated fluid 5 flows, inside a flow passage 10 through which the exhaust gas 3 flows.

[0013] The flow passage 10 comprises a housing 11 having a circular or rectangular cross-section, an inlet 12 into which exhaust gas 3 flows, an outlet 14 into which 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 with the horizontal direction as its 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 or overhead via a base or support (not shown). The inner surface of the flow passage 10 is covered with thermal insulation material.

[0014] The heat recovery device 1 includes a first expansion joint 17, an inlet pipe 43, a support member 30, a heat transfer tube group 20, a joint 25, a second expansion joint 45, a connecting duct 50, and an outlet pipe 47. In the heat recovery device 1 shown in Figure 1, the inlet pipe 43, support member 30, heat transfer tube group 20, support member 30, a connecting duct 50 located below, a support member 30, a heat transfer tube group 20, a support member 30, a connecting duct 50 located above, a support member 30, a heat transfer tube group 20, a support member 30, a connecting duct 50 located below, a support member 30, a heat transfer tube group 20, a support member 30, and an outlet pipe 47 are connected in that order.

[0015] The inlet pipe 43 is located downstream of the flow passage 10, and the outlet pipe 47 is located upstream of the flow passage 10. The fluid to be heated 5 introduced from the inlet pipe 43 flows sequentially through the support member 30, the heat transfer tube group 20, the connecting duct 50, etc., and is then discharged from the outlet pipe 47. However, as it flows through the heat transfer tube group 20, it is heated by receiving exhaust heat from the exhaust gas 3. The fluid to be heated 5 is, for example, combustion air or combustion gas used in a burner.

[0016] The connecting duct 50 is disposed outside the flow passage 10. By being exposed to 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 state of being separated 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 joining portion 25. The joining portion 25 is a welded portion formed by, for example, welding. Since the heat transfer tube group 20 is firmly fixed to the support member 30 by the joining 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 connecting the support member 30 to which the heat transfer tube group 20 is joined and fixed by the joining portion 25 to the flow passage 10 in a displaceable manner. By interposing the first expansion joint 17 between the flow passage 10 and the support member 30, the 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. Thus, 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. <​​​​​​​​​​​​​​​​As shown in Figure 3, the waste heat recovery device 1 according to the second embodiment is characterized by comprising, for example, a fabric-type non-metallic expansion joint 41 as the first expansion joint 17 and the second expansion joint 45.

[0026] The fabric-type non-metallic expansion joint 41 is, for example, a thick woven fabric made by heat-pressing a Teflon® sheet onto an inorganic fiber cloth and integrating them, and is flexible. Although the fabric-type non-metallic expansion joint 41 has inferior heat resistance compared to the bellows-type metal expansion joint, it can be used sufficiently in environments where the temperature of the exhaust gas 3 is not very high, and has the advantage of being easy to create the desired shape due to its high flexibility. As a result, the expansion joints 17 and 45 can be constructed at low cost.

[0027] It is undesirable for the fabric-type non-metallic expansion joint 41 to be exposed to radiant heat from the heat transfer tube group 20 through which the high-temperature exhaust gas 3 and the heated fluid 5 flow in the flow passage 10 are transmitted. Therefore, the inner surface of the fabric-type non-metallic expansion joint 41 is covered with an insulating material (not shown). Alternatively, a labyrinth 42 made of a heat-resistant material (e.g., metal) is arranged circumferentially inside the fabric-type non-metallic expansion joint 41. The labyrinth 42 has a maze structure with minute gaps and is configured to slide along the length L of the heat transfer tube group 20. The labyrinth 42 provided inside the fabric-type non-metallic expansion joint 41 acts as a heat shield that blocks heat from reaching the fabric-type non-metallic expansion joint 41. This reduces the thermal damage to the fabric-type non-metallic expansion joint 41.

[0028] [Third Embodiment] The waste heat recovery device 1 according to the third embodiment will be described with reference to Figure 4. Figure 4 is a schematic diagram illustrating the slide support structure 70 in the waste heat recovery device 1 according to the third embodiment.

[0029] The heat recovery device 1 according to the third embodiment has a structure that can be commonly used for either the first expansion joint 17 or the second expansion joint 45, and includes the slide support structure 70 shown in Figure 4. Here, when a long expansion section is required, the expansion joints 17 and 45 are connected vertically via a stroke restricting plate 75 with a hole 81 in the center. To prevent buckling or twisting due to its length, the stroke restricting plate 75 is used as an intermediate connection, and the first restricting rod 76 and the second restricting rod are used to maintain its self-support and ensure linear movement in the structure described below. The slide support structure 70 has the function of sliding and supporting the support member 30 so that the support member 30 is displaced in the longitudinal direction L of the heat transfer tube group 20 when the heat transfer tube group 20 undergoes thermal expansion. The slide support structure 70 is arranged on the outside so as to surround the expansion joints 17 and 45, i.e., the first expansion joint 17 or the second expansion joint 45.

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

[0031] A guide rod 73 is erected on one flange 71, and a guide cylinder 74 is erected on the other flange 72. The guide rod 73 and the guide cylinder 74 extend along the length L of the heat transfer tube group 20. The resin portion at the tip of the guide rod 73 is inserted into the guide cylinder 74 and configured to slide along the length L of the heat transfer tube group 20. By making the tip of the guide rod 73 out of resin in this way, sliding with the guide cylinder 74 is facilitated.

[0032] A stroke restricting section 75 is attached to the central outer circumference of the first expansion joint 17 and the second expansion joint 45, extending outward. The stroke restricting section 75 is provided with a first restricting rod 76, which is provided on one flange 71 and extends toward the other flange 72, and a second restricting rod 77, which is provided on the other flange 72 and extends toward the one flange 71. Stoppers 79 are provided at the ends of the first restricting rod 76 and the second restricting rod 77. In Figure 4, the expansion joints 17 and 45 are in an extended state, and the stoppers 79 provided on the first restricting rod 76 and the second restricting rod 77 contact the stroke restricting section 75, restricting them from extending further. When the expansion joints 17 and 45 are retracted, the stoppers 79 are separated from the stroke restricting plate 75.

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

[0034] Therefore, by providing the slide support structure 70, when the heat transfer tube group 20 undergoes thermal expansion, the support member 30 can be smoothly displaced in the longitudinal direction L of the heat transfer tube group 20. In addition, since the long expansion 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 this invention have been described, this invention is not limited to the above embodiments and can be implemented with various modifications within the scope of this invention.

[0036] In the above embodiment, the same type of expansion joint is used for the first expansion joint 17 and the second expansion joint 45. However, different types of expansion joints can be used for the first expansion joint 17 and the second expansion joint 45. Specifically, a heat-resistant bellows-type metal expansion joint can be used for the first expansion joint 17, and a fabric-type non-metallic expansion joint can be used for the second expansion joint 45 to enable lower costs.

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

[0038] This invention and its embodiments can be summarized as follows:

[0039] One embodiment of this invention is a waste heat recovery device 1, A heat recovery device 1 is provided with a group of heat transfer tubes 20 through which a heated fluid 5 flows, located inside a flow passage 10 through which exhaust gas 3 flows, A support member 30 that supports the end 22 of the heat transfer tube group 20, A joint 25 that joins and fixes the end 22 of the heat transfer tube group 20 to the support member 30, The present invention is characterized by comprising 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 25.

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

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

[0042] According to the above embodiment, the displacement of the support member 30 relative to the flow passage 10 is made possible.

[0043] Furthermore, in one embodiment of the waste heat recovery device 1, The system further includes connecting ducts 50 connected to adjacent support members 30, The expansion joint 45 is interposed between the connecting duct 50 and the support member 30 so as to allow the support member 30 to be displaced relative to the connecting duct 50.

[0044] According to the above embodiment, the support member 30 can be displaced relative to the connecting duct 50.

[0045] Furthermore, in one embodiment of the waste heat recovery device 1, The connecting duct 50 is installed outside the flow passage 10.

[0046] According to the above embodiment, it is possible to reduce the thermal stress caused by the temperature difference in the connecting duct 50 when the connecting duct 50 comes into contact with the high-temperature exhaust gas 3.

[0047] Furthermore, in one embodiment of the waste heat recovery device 1, The aforementioned expansion joints 17 and 45 are bellows-type metal expansion joints.

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

[0049] Furthermore, in one embodiment of the waste heat recovery device 1, The aforementioned expansion joints 17 and 45 are fabric-type non-metallic expansion joints.

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

[0051] Furthermore, in one embodiment of the waste heat recovery device 1, The system further includes a sliding support structure 70 that slides and supports the support member 30 so that the support member 30 is displaced 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 undergoes thermal expansion, the support member 30 can be smoothly displaced in the longitudinal direction L of the heat transfer tube group 20. [Explanation of Symbols]

[0053] 1… Heat recovery device (recuperator) 3… Exhaust gas 5...Fluid to be heated 10... Distribution path 11…Cabinet 12…Inflow part 14…Outlet 15...Aperture 17…First expansion joint (expansion joint) 20…Heat transfer tube group 22...end 25…Joint part 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 legs 70...Slide support structure 71...One-sided flange 72...Other side flange 73… Guide Rod 74... Guide tube 75... Stroke limiting plate 76...First regulated rod 77...Second regulation rod 78… Heat-shielding cover 79... Stopper 81…hole L...Length direction

Claims

1. A heat recovery device that includes a group of heat transfer tubes through which a heated fluid flows, located inside a flow passage through which exhaust gas flows, A support member that supports the end of the heat transfer tube group, A joint portion for joining and fixing the end of the heat transfer tube group to the support member, A heat recovery device comprising: an expansion joint that displaces the support member to which the heat transfer tube group is joined and fixed by the joint; and an expansion joint that connects the support member to the support member in a displaceable manner.

2. The exhaust heat recovery device according to claim 1, wherein the expansion joint is interposed between the flow passage and the support member so as to allow displacement of the support member relative to the flow passage.

3. The system further includes connecting ducts connected to adjacent support members, The exhaust heat recovery device according to claim 1, wherein the expansion joint is interposed between the connecting duct and the support member so as to allow displacement of the support member relative to the connecting duct.

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

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

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

7. The waste heat recovery apparatus according to claim 1, further comprising a sliding support structure that slides and supports the support member such that the support member is displaced in the longitudinal direction of the heat transfer tube group.

Images