A heat exchange device resistant to high temperature, high pressure and hydrogen corrosion

Abstract

The invention discloses a heat exchange device resistant to high temperature, high pressure and hydrogen corrosion, which comprises a shell and a tube sheet arranged in the shell, the tube sheet divides the inner cavity of the shell into a heat exchange cavity and a refrigerant cavity; the refrigerant cavity is divided into a liquid inlet cavity and a liquid outlet cavity; an insulation tube and a high-temperature inner box are installed in the heat exchange cavity, and the two ends of the U-shaped heat exchange tube are connected to the liquid inlet cavity and the liquid outlet cavity through the tube sheet; a connecting portion connecting the inside and outside of the insulation tube is provided between the insulation tube and the tube sheet; the high-temperature inner box is connected to the insulation tube; a gas inlet pipe and a gas outlet pipe are arranged on the shell, the gas inlet pipe is directly opposite to the high-temperature inner box and connected to the high-temperature inner box, and the gas outlet pipe is directly opposite to the connecting portion; a first thermal insulation material is filled between the high-temperature inner box and the shell, and the annular gap between the insulation tube and the cylinder body forms a dead gas zone, and the dead gas zone is connected to the inner cavity of the insulation tube through the connecting portion. By using the present application, the manufacturing cost of the equipment can be well reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical equipment, and in particular relates to a heat exchange device resistant to high temperature, high pressure and hydrogen corrosion. Background Art

[0002] At present, the shell-and-tube heat exchanger is commonly used to recover the reaction heat of the synthesis gas reaction. Since the temperature of the synthesis gas is relatively high and it contains a high concentration of hydrogen, in order to ensure the safe operation of the heat exchanger, the equipment needs to be made of materials that are resistant to high temperature and strong hydrogen corrosion, resulting in a high production cost of the heat exchanger and a high maintenance cost of the equipment, causing the purchase cost of the reaction heat recovery device to remain high. Summary of the invention

[0003] In view of the problem of high manufacturing cost of existing reaction heat recovery devices, the present application proposes a heat exchange device resistant to high temperature, high pressure and hydrogen corrosion, which includes a shell and a tube sheet arranged in the shell, the shell includes a cylinder, a first sealing flat cover and a second sealing flat cover arranged at both ends of the cylinder, the tube sheet divides the inner cavity of the shell into a heat exchange cavity and a refrigerant cavity, wherein the heat exchange cavity is located between the tube sheet and the first flat cover, and the refrigerant cavity is located between the tube sheet and the second flat cover;

[0004] A partition plate is installed in the refrigerant cavity, and the partition plate divides the refrigerant cavity into a liquid inlet cavity and a liquid outlet cavity which are not connected to each other; a heat transfer medium inlet connected to the liquid inlet cavity and a heat transfer medium outlet connected to the liquid outlet cavity are installed on the outer shell; an insulation cylinder and a high-temperature inner connection box are installed in the heat exchange cavity, and a U-shaped heat exchange tube is installed in the insulation cylinder, and the two ends of the U-shaped heat exchange tube are respectively connected to the liquid inlet cavity and the liquid outlet cavity through the tube sheet; the end of the insulation cylinder facing the tube sheet is an open end, and a connecting part connecting the inside and outside of the insulation cylinder is provided between the open end and the tube sheet;

[0005] The high-temperature inner box is located on the side of the heat-insulating tube away from the tube sheet, and the high-temperature inner box is connected to the heat-insulating tube; a gas inlet pipe and a gas outlet pipe are arranged on the outer shell, the gas inlet pipe is directly opposite to the high-temperature inner box and connected to the high-temperature inner box, and the gas outlet pipe is directly opposite to the connecting part;

[0006] A first heat-insulating material is filled between the high-temperature inner box and the outer shell, and the annular gap between the heat-insulating cylinder and the cylinder body forms a dead air zone, which is connected to the inner cavity of the heat-insulating cylinder through the connecting part. The distance between the heat-insulating cylinder and the outer shell is 50-100 mm.

[0007] The gas inlet pipe is facing the high temperature inner box, which means that the gas inlet pipe is located in the area of ​​the cylinder corresponding to the high temperature inner box in the radial direction. The gas outlet pipe is facing the connecting part, which means that the gas outlet pipe is located in the area of ​​the cylinder corresponding to the connecting part in the radial direction.

[0008] To facilitate manufacturing, installation and maintenance, the partition plate has a radially extending bent portion, a manhole is formed on the bent portion, and a blind plate is installed on the manhole, through which the components surrounded by the partition plate can be conveniently installed and maintained.

[0009] The present application is mainly used in ammonia synthesis process, and is used to recover the reaction heat of synthesis gas in the ammonia synthesis process. When the heat exchange device is working, the synthesis gas can enter the annular gap between the insulation cylinder and the cylinder body through the connecting part. Since the end of the annular gap facing the first flat cover is a closed end, the synthesis gas entering the annular gap is basically in a static state without flowing. Therefore, the annular gap between the insulation cylinder and the cylinder body is called a dead gas zone. Since the gas is a poor conductor of heat, it can play a role of heat insulation. At the same time, the insulation cylinder as a whole can be surrounded by the synthesis gas, which can reduce the compressive strength of the insulation cylinder, reduce the wall thickness of the insulation cylinder, and reduce the manufacturing cost of the equipment.

[0010] In the present application, the gas outlet pipe is directly opposite to the connecting part, so that the synthesis gas is discharged from the heat exchange device directly through the gas outlet pipe after flowing out of the heat insulation cylinder. Since most areas of the shell are no longer directly in contact with the high-temperature synthesis gas, the areas that are not directly in contact with the high-temperature synthesis gas can be prepared with lower-grade materials, thereby reducing the manufacturing cost of the equipment. The provision of the first insulation layer can effectively reduce the heat transfer of the synthesis gas to the outside when passing through the high-temperature inner box, and avoid excessive temperature increase of the part of the shell around the high-temperature inner box.

[0011] At the same time, since the synthesis gas in the dead gas zone is basically in a static state, the temperature is reduced to a certain extent, which can effectively reduce the pressure of the shell. By using this application, most areas of the shell can be lower than 400°C, so that ordinary materials can be used to make it, thereby reducing the manufacturing cost of the equipment.

[0012] Furthermore, in order to evenly distribute the synthesis gas in the heat-insulating cylinder, a gas distributor is provided between the high-temperature inner header box and the heat-insulating cylinder. Preferably, the gas distributor is a spherical cone plate with a central portion protruding toward the high-temperature inner header box, and an air hole is provided at the radial outer end of the spherical cone plate. After the gas distributor is made of the spherical cone plate, and an air hole is provided at the radial outer end of the spherical cone plate, since the radial outer end of the spherical cone plate is inclined, after the synthesis gas enters the heat-insulating cylinder through the air hole, it will move toward the central area of ​​the heat-insulating cylinder under the action of inertia, and due to the obstruction of the U-shaped heat exchange tube, the synthesis gas is evenly distributed in the heat-insulating cylinder.

[0013] Furthermore, a first sealing diaphragm pad is provided between the first flat cover and the cylinder body, and the first sealing diaphragm pad completely isolates the first flat cover from the heat exchange cavity, and a first sealing surface formed by surfacing welding of Inconel600 material is provided on the end surface of the cylinder body facing the first flat cover;

[0014] A second sealing diaphragm pad is provided between the second flat cover and the cylinder body, and the second sealing diaphragm pad completely isolates the second flat cover from the refrigerant cavity. A second sealing surface formed by surfacing welding of Inconel600 material is provided on the end surface of the cylinder body facing the second flat cover.

[0015] The first sealing diaphragm pad and the second sealing diaphragm pad are preferably made of 321SS stainless steel. The first flat cover is preferably made of 1Cr5Mo alloy steel, and the second flat cover is preferably made of 20MnMo alloy steel.

[0016] After the first sealing diaphragm and the second sealing diaphragm pad are arranged, the first flat cover and the second flat cover can be avoided from directly contacting with the synthesis gas, and the hydrogen corrosion resistance requirements of the first flat cover and the second flat cover are reduced. Only their temperature resistance performance needs to be considered, thereby reducing the production cost of the first flat cover and the second flat cover. The first sealing diaphragm pad and the second sealing diaphragm pad can be made of materials with better corrosion resistance, and they can be easily replaced.

[0017] Furthermore, in order to improve the heat insulation performance, a heat insulation layer is wrapped on the outer peripheral surface of the heat insulation cylinder, and the annular gap between the heat insulation layer and the cylinder body forms the dead air zone.

[0018] Furthermore, a surfacing sealing layer is provided on the first end surface of the tube sheet facing the first flat cover, the surfacing sealing layer covers the area of ​​the first end surface of the tube sheet located in the heat exchange cavity, and the surfacing sealing layer extends from the first end surface along the inner surface of the cylinder toward the first flat cover until it exceeds the end surface of the insulation layer facing the second flat cover. The thickness of the surfacing sealing layer is preferably 3.5-4.5 mm.

[0019] The cladding layer in the present application is only set in the high-temperature area in direct contact with the synthesis gas. By using the cladding layer, high-temperature resistant materials can be used to make the components in this area without using materials resistant to hydrogen corrosion, thereby reducing the corrosion resistance level of the material and reducing the manufacturing cost of the equipment. Since the cladding layer seals the welds in the corresponding area to form a weld-free area, hydrogen corrosion that may be caused to the area by the high concentration of hydrogen in the synthesis gas at high temperature is avoided. The setting of the dead gas zone can reduce the temperature of the cylinder area opposite to the dead gas zone, so that the temperature of this part of the area is less than 400°C, and there is no need to use a cladding layer for protection. The U-shaped heat exchange tube is inserted into the tube sheet through the cladding layer, so that the weld between the U-shaped heat exchange tube and the tube sheet is in the heat transfer medium, avoiding the weld between the U-shaped heat exchange tube and the tube sheet from being exposed to the synthesis gas, which is beneficial to the protection of the tube head of the U-shaped heat exchange tube.

[0020] Furthermore, in order to ensure that the high-temperature area has the ability to resist hydrogen corrosion, the surfacing sealing layer exceeds the end surface of the insulation layer facing the second flat cover by at least 100 mm.

[0021] Furthermore, when viewed in the radial direction, the surfacing sealing layer covers the connecting portion, and the surfacing sealing layer extends to the inner wall of the gas outlet pipe and covers the inner wall of the gas outlet pipe. This design can protect the area in contact with the synthesis gas to the maximum extent.

[0022] Furthermore, in order to avoid internal stress concentration caused by the inability of the insulation tube to freely expand and contract at high temperatures, the end of the insulation tube facing the tube sheet is a free end, and a leg is installed on the free end, and the leg is slidably supported on the cladding sealing layer. There are several legs, and the synthetic gas can enter the dead gas zone from the pores between the legs and the gaps between the legs and the cladding sealing layer. After the free end is set, the insulation tube can freely expand and contract with the change of temperature, avoiding deformation and cracking caused by the generation of internal stress, which affects the normal operation of the equipment.

[0023] Specifically, the cylinder includes a high-temperature cavity, a main cavity and a tube-side cavity in sequence along the direction from the first flat cover to the second flat cover, wherein the high-temperature cavity and the main cavity are welded together, and the two ends of the tube sheet are respectively welded to the main cavity and the tube-side cavity; the gas inlet pipe is arranged on the high-temperature cavity, the gas outlet pipe is arranged at one end of the main cavity facing the tube sheet, and the heat transfer medium inlet and the heat transfer medium outlet are arranged on the tube-side cavity;

[0024] The materials of the high-temperature cavity, main cavity and tube sheet are all 12Cr2Mo1 alloy steel, the material of the tube side cavity is, and the material of the tube side cavity is 15CrMo alloy steel.

[0025] After the cylinder is divided into multiple sections, different thickness and material requirements can be set according to the different temperature zones of the high-temperature cavity, the main cavity and the tube cavity, so as to avoid the difficulty of mechanical processing when a single cylinder is used.

[0026] Furthermore, when the heat exchange device is working, the synthesis gas enters the high-temperature inner box from the gas inlet pipe, and then enters the heat insulation cylinder to exchange heat with the heat transfer medium in the U-shaped heat exchange tube. After the heat exchange is completed, the synthesis gas is discharged from the gas outlet pipe; the heat transfer medium enters the U-shaped heat exchange tube through the heat transfer medium inlet and the liquid inlet cavity in turn, exchanges heat with the synthesis gas, and then is discharged through the liquid outlet cavity and the heat transfer medium outlet in turn;

[0027] The inlet temperature of the syngas is 435-450°C, and the outlet temperature of the syngas is 405-420°C; the temperature of the area of ​​the cylinder opposite to the dead gas zone in the radial direction is lower than 400°C. The heat transfer medium is non-corrosive medium such as steam, water or heat transfer oil.

[0028] When steam is used as the heat transfer medium, the steam is saturated steam at 250-260°C. After heat exchange, the saturated steam becomes superheated steam at a temperature of 395-405°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of an embodiment of the present invention.

[0030] Figure 2 yes Figure 1 Enlarged view of part A.

[0031] Figure 3 yes Figure 1 Enlarged view of part B.

[0032] Figure 4 yes Figure 1 Magnified view of part C. DETAILED DESCRIPTION

[0033] See also Figure 1 A heat exchange device resistant to high temperature, high pressure and hydrogen corrosion, comprising a shell, a tube sheet 11 arranged in the shell, the shell comprising a cylinder 60, a first sealing flat cover 24 and a second sealing flat cover 14 arranged at both ends of the cylinder, the tube sheet 11 divides the inner cavity of the shell into a heat exchange cavity 21 and a refrigerant cavity 22, wherein the heat exchange cavity is located between the tube sheet 11 and the first flat cover 24, and the refrigerant cavity is located between the tube sheet 11 and the second flat cover 14. The shell is horizontal, the first flat cover 24 is installed on the cylinder through the first bolt 17, and the second flat cover 14 is installed on the cylinder through the second bolt 27.

[0034] See also Figure 3 A first sealing diaphragm gasket 28 is installed between the first flat cover 24 and the cylinder 60. The first sealing diaphragm gasket 28 completely isolates the first flat cover 24 from the heat exchange chamber 21. A first sealing surface 41 formed by surfacing welding of Inconel600 material is provided on the end surface of the cylinder 60 facing the first flat cover 24. In the accompanying drawings, the first sealing surface 41 is a black square.

[0035] See also Figure 4 A second sealing diaphragm pad 18 is installed between the second flat cover 14 and the cylinder 60. The second sealing diaphragm pad 18 completely isolates the second flat cover 14 from the refrigerant chamber 22. A second sealing surface 13 formed by surfacing of Inconel 600 material is provided on the end surface of the cylinder 60 facing the second flat cover 14. In the accompanying drawings, the second sealing surface 13 is a black square.

[0036] The first sealing diaphragm pad and the second sealing diaphragm pad are both made of 321SS stainless steel. The first flat cover 24 is made of 1Cr5Mo alloy steel, and the second flat cover 14 is made of 20MnMo alloy steel.

[0037] A partition plate 19 is installed in the refrigerant cavity, and the partition plate divides the refrigerant cavity into a liquid inlet cavity 221 and a liquid outlet cavity 222 which are not connected to each other; a heat transfer medium inlet 15 connected to the liquid inlet cavity 221 and a heat transfer medium outlet 12 connected to the liquid outlet cavity 222 are installed on the shell. The partition plate 19 is a folded plate, one side of the folded plate is welded to the tube plate 11, and the other side is welded to the cylinder 60. The space surrounded by the partition plate 19 and the cylinder 60 forms the liquid outlet cavity 222. The folded plate has no contact with the second flat cover 14, so as to facilitate the installation of the second flat cover 14.

[0038] The partition plate 19 has a bent portion 191 extending radially along the cylinder 60, and a manhole 192 is provided on the bent portion 191. The connection between the U-shaped heat exchange tube 81 and the tube sheet described below can be maintained through the manhole 192, and a blind plate 193 is installed on the manhole 192.

[0039] An insulating tube 9 and a high-temperature inner box 16 are installed in the heat exchange cavity. A deflector rod assembly 10 and a U-shaped heat exchange tube bundle 8 composed of a plurality of U-shaped heat exchange tubes 81 are installed in the insulating tube 9. The U-shaped heat exchange tube 81 is movably supported on the deflector rod 33 in the deflector rod assembly 10.

[0040] One end of the heat insulating tube 9 facing the tube sheet 11 is a free end, and a support leg 92 is installed on the end of the free end.

[0041] A gas distributor 7 is provided between the high-temperature inner box 16 and the insulation tube 9. The gas distributor is a spherical cone plate with a central portion protruding toward the high-temperature inner box. An air hole is provided at the radial outer end of the spherical cone plate. The air hole connects the high-temperature inner box 16 and the insulation tube 9. In the attached figure, the air hole is not shown, and only the center line 71 of the air hole is shown.

[0042] Both ends of each U-shaped heat exchange tube 81 are welded to the tube sheet 11, and the two ends of the U-shaped heat exchange tube are respectively connected to the liquid inlet chamber 221 and the liquid outlet chamber 222; the end of the insulation tube 9 facing the tube sheet 11 is an open end, and a connecting portion 91 connecting the inside and outside of the insulation tube is provided between the open end and the tube sheet.

[0043] The high temperature inner box 16 is located on the side of the insulation tube 9 away from the tube sheet 11, and the high temperature inner box is connected to the insulation tube; a gas inlet pipe 31 and a gas outlet pipe 5 are arranged on the outer shell, the gas inlet pipe is directly opposite to the high temperature inner box and connected to the high temperature inner box, and the gas outlet pipe is directly opposite to the connecting part. The extension pipe 100 of the internal part of the synthesis tower is connected to the second flange 311 on the gas inlet pipe 31 through the first flange 101, and an omega sealing ring 102 is arranged between the first flange and the second flange.

[0044] The first heat-insulating material 211 is filled between the high-temperature inner box 16 and the outer shell. In this embodiment, the first heat-insulating material is made of aluminum silicate fiber felt.

[0045] In this embodiment, the heat-insulating cylinder is coaxially arranged with the cylinder, and the distance between the heat-insulating cylinder and the outer shell is 80 mm, that is, the difference between the outer diameter of the heat-insulating cylinder and the inner diameter of the cylinder is 160 mm, and a 40 mm thick insulation layer 93 is wrapped on the outer circumference of the heat-insulating cylinder, and the annular gap between the insulation layer 93 and the cylinder forms a dead air zone 35. It can be understood that when there is no insulation layer 93, the annular gap between the heat-insulating cylinder and the cylinder forms a dead air zone 35.

[0046] See also Figure 2 A cladding sealing layer 70 is provided on the first end surface 111 of the tube sheet 11 facing the first flat cover 24. The cladding sealing layer 70 covers the area of ​​the first end surface of the tube sheet located in the heat exchange chamber 21, and the cladding sealing layer 70 extends from the first end surface along the inner surface of the cylinder 60 toward the first flat cover 24 until it exceeds the end surface of the insulation layer 93 facing the second flat cover 14. The cladding sealing layer 70 exceeds the end surface of the insulation layer facing the second flat cover, continues to extend toward the first flat cover 24, and exceeds the end surface of the insulation layer facing the second flat cover. The length M of the cladding sealing layer exceeding the end surface of the insulation layer facing the second flat cover is 100 mm.

[0047] Observed in the radial direction, the surfacing sealing layer 70 covers the connecting portion, and the surfacing sealing layer 70 extends to the inner wall 51 of the gas outlet pipe 5, covers the inner wall of the gas outlet pipe, and then extends to the outer end surface 52 of the gas outlet pipe.

[0048] The legs 92 on the heat insulating tube 9 are slidably supported on the cladding sealing layer 70. The dead gas zone 35 is connected to the inner cavity of the heat insulating tube through the gaps between the adjacent legs and the connecting portion 91. Since the legs are slidably supported on the cladding sealing layer 70, there is also a certain gap between the legs and the cladding sealing layer 70, and the gas can also pass through the gap between the legs and the cladding sealing layer 70 and enter the dead gas zone.

[0049] In this embodiment, the thickness of the surfacing sealing layer 70 is 4.0 mm. It can be understood that in other embodiments, the thickness of the surfacing sealing layer can also be 3.5 mm, 3.7 mm, 3.9 mm, 4.1 mm, 4.3 mm or 4.5 mm, and of course, it can also be other thicknesses between 3.5-4.5 mm.

[0050] In this embodiment, the cylinder 60 includes a high-temperature cavity 4, a main cavity 6 and a tube-side cavity 1 in sequence along the direction from the first flat cover 24 to the second flat cover 14, wherein the high-temperature cavity 4 and the main cavity 6 are welded together, and the two ends of the tube sheet 11 are respectively welded to the main cavity 6 and the tube-side cavity 1.

[0051] A shower pipe 23 is installed at the lower side of the high-temperature cavity 4, and a movable support 25 is installed at the lower side of the cylinder.

[0052] The gas inlet pipe 31 is arranged on the high temperature cavity 4, the gas outlet pipe is arranged on one end of the main cavity 6 facing the tube sheet 11, and the heat transfer medium inlet 15 and the heat transfer medium outlet 12 are arranged on the tube side cavity 1. The heat transfer medium inlet 15 is located at the lower side of the tube side cavity 1, and the heat transfer medium outlet 12 is located at the upper side of the tube side cavity 1.

[0053] The materials of the high-temperature cavity, main cavity and tube sheet are all 12Cr2Mo1 alloy steel, the material of the tube side cavity is, and the material of the tube side cavity is 15CrMo alloy steel.

[0054] When the heat exchange device in this embodiment is working, the synthesis gas enters the high-temperature inner box 16 through the gas inlet pipe 100, and then enters the heat insulation tube 9 to exchange heat with the heat transfer medium in the U-shaped heat exchange tube. After the heat exchange is completed, the synthesis gas is discharged from the gas outlet pipe 5. The heat transfer medium enters the U-shaped heat exchange tube through the heat transfer medium inlet 15 and the liquid inlet cavity 221, exchanges heat with the synthesis gas, and then is discharged through the liquid outlet cavity 222 and the heat transfer medium outlet 12 in sequence.

[0055] The inlet temperature of the synthesis gas is 440±5°C, and the outlet temperature of the synthesis gas is 405-410°C; the temperature of the area of ​​the cylinder opposite to the dead gas zone in the radial direction is 395-398°C.

[0056] In this embodiment, the heat transfer medium is saturated steam, and the inlet temperature of the saturated steam at the heat transfer medium inlet 15 is 250-260°C. After passing through the U-shaped heat exchange tube, the saturated steam becomes superheated steam with a temperature of 395-405°C.

[0057] It can be understood that in other embodiments, the heat transfer medium may also be water or heat transfer oil.

Claims

1. A heat exchange device resistant to high temperature, high pressure, and hydrogen corrosion, characterized in that: The invention comprises an outer shell and a tube sheet arranged in the outer shell, wherein the outer shell comprises a cylinder, a first sealing flat cover and a second sealing flat cover arranged at both ends of the cylinder, the tube sheet divides the inner cavity of the outer shell into a heat exchange cavity and a refrigerant cavity, wherein the heat exchange cavity is located between the tube sheet and the first flat cover, and the refrigerant cavity is located between the tube sheet and the second flat cover; a partition plate is installed in the refrigerant cavity, and the partition plate divides the refrigerant cavity into a liquid inlet cavity and a liquid outlet cavity which are not connected to each other; a heat transfer medium inlet connected to the liquid inlet cavity and a heat transfer medium outlet connected to the liquid outlet cavity are installed on the outer shell; an insulating cylinder and a high-temperature inner connection box are installed in the heat exchange cavity, a U-shaped heat exchange tube is installed in the insulating cylinder, and the U-shaped heat exchange tube The two ends are connected to the liquid inlet cavity and the liquid outlet cavity respectively through the tube sheet; the end of the insulation tube facing the tube sheet is an open end, and a connecting part connecting the inside and outside of the insulation tube is provided between the open end and the tube sheet; the high-temperature inner box is located on the side of the insulation tube away from the tube sheet, and the high-temperature inner box is connected to the insulation tube; a gas inlet pipe and a gas outlet pipe are provided on the outer shell, the gas inlet pipe is opposite to the high-temperature inner box and connected to the high-temperature inner box, and the gas outlet pipe is opposite to the connecting part; a first thermal insulation material is filled between the high-temperature inner box and the outer shell, and the annular gap between the insulation tube and the cylinder body forms a dead air zone, and the dead air zone is connected to the inner cavity of the insulation tube through the connecting part.

2. The heat exchange device according to claim 1, characterized in that: A gas distributor is arranged between the high-temperature inner box and the heat-insulating cylinder.

3. The heat exchange device according to claim 1, characterized in that: A first sealing diaphragm gasket is provided between the first flat cover and the cylinder body, and the first sealing diaphragm gasket completely isolates the first flat cover from the heat exchange chamber, and a first sealing surface formed by surfacing welding of Inconel600 material is provided on the end surface of the cylinder body facing the first flat cover; a second sealing diaphragm gasket is provided between the second flat cover and the cylinder body, and the second sealing diaphragm gasket completely isolates the second flat cover from the refrigerant chamber, and a second sealing surface formed by surfacing welding of Inconel600 material is provided on the end surface of the cylinder body facing the second flat cover.

4. The heat exchange device according to claim 1, characterized in that: The outer peripheral surface of the heat-insulating cylinder is wrapped with a heat-insulating layer, and the annular gap between the heat-insulating layer and the cylinder body forms the dead air zone.

5. The heat exchange device according to claim 4, characterized in that: A surfacing sealing layer is arranged on the first end surface of the tube sheet facing the first flat cover. The surfacing sealing layer covers the area of ​​the first end surface of the tube sheet located in the heat exchange cavity, and the surfacing sealing layer extends from the first end surface along the inner surface of the cylinder toward the first flat cover until it exceeds the end surface of the insulation layer facing the second flat cover.

6. The heat exchange device according to claim 5, characterized in that: The surfacing sealing layer exceeds the end surface of the thermal insulation layer facing the second flat cover by at least 100 mm.

7. The heat exchange device according to claim 5, characterized in that: When viewed in the radial direction, the surfacing sealing layer covers the connecting portion, and the surfacing sealing layer extends to the inner wall of the gas outlet pipe and completely covers the inner wall of the gas outlet pipe.

8. The heat exchange device according to claim 5, characterized in that: One end of the heat-insulating cylinder facing the tube sheet is a free end, on which a support leg is mounted, and the support leg is slidably supported on the surfacing sealing layer.

9. The heat exchange device according to claim 1, characterized in that: The cylinder includes a high-temperature cavity, a main cavity and a tube-side cavity in sequence along the direction from the first flat cover to the second flat cover, wherein the high-temperature cavity and the main cavity are welded together, and the two ends of the tube sheet are respectively welded to the main cavity and the tube-side cavity; the gas inlet pipe is arranged on the high-temperature cavity, the gas outlet pipe is arranged at one end of the main cavity facing the tube sheet, and the heat transfer medium inlet and the heat transfer medium outlet are arranged on the tube-side cavity; the materials of the high-temperature cavity, the main cavity and the tube sheet are all 12Cr2Mo1 alloy steel, and the material of the tube-side cavity is 15CrMo alloy steel.

10. The heat exchange device according to any one of claims 1 to 9, characterized in that: When the heat exchange device is working, the synthesis gas enters the high-temperature inner box from the gas inlet pipe, and then enters the insulation cylinder to exchange heat with the heat transfer medium in the U-shaped heat exchange tube. The synthesis gas after the heat exchange is discharged from the gas outlet pipe; the heat transfer medium enters the U-shaped heat exchange tube through the heat transfer medium inlet and the liquid inlet cavity in turn, exchanges heat with the synthesis gas, and then is discharged through the liquid outlet cavity and the heat transfer medium outlet in turn; the inlet temperature of the synthesis gas is 435-450℃, and the outlet temperature of the synthesis gas is 405-420℃; the temperature of the area of ​​the cylinder opposite to the dead gas zone in the radial direction is lower than 400℃.

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