Prestressed compensating device for reducing the bottom stress in coil-type raw gas heat exchanger

Abstract

The present invention discloses a prestressed compensating device for reducing the bottom stress in a coil-type raw gas heat exchanger, and belongs to the field of coking technology. The outer shell of the coil-type raw gas heat exchanger is composed of an upper shell section and a lower shell section that are sealed together. The prestressed compensating device is arranged on the lower flange of the coil-type raw gas heat exchanger and is connected to the upper shell section. The prestressed compensating device is used to apply an upward thrust to the upper shell section and can adjust the magnitude of the thrust. The prestressed compensating device of the present invention can directly and effectively reduce the bottom stress in the entire coking turnover cycle, eliminate the hidden dangers of cracking and damage of the raw gas heat exchanger, and ensure the safe operation of the equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of coking, and in particular relates to a prestressed compensating device for reducing the bottom stress in a coil-type raw coal gas heat exchanger. Background Art

[0002] During the coking process, coking coal is loaded into the coke oven carbonization chamber, where it is isolated from the air and distilled to generate a large amount of raw coal gas. The raw coal gas leaves the carbonization chamber at a temperature of 650-950°C. After passing through the riser, tee, and bridge pipe to the gas collecting pipe, it is transported to the gas purification process. The high-temperature raw coal gas is cooled to about 80-85°C by spraying circulating ammonia water at the bridge pipe, and a large amount of sensible heat is wasted. If the waste heat of the raw coal gas is recycled and used to produce medium and low-pressure steam for the coking plant's own use, it is one of the effective means to reduce the energy consumption of the coking process and reduce the carbon emission intensity.

[0003] In a coke oven carbonization chamber turnover cycle, the temperature of the gas flowing through the riser stage changes periodically, such as Figure 1 As shown, the temperature during the coal loading and coke pushing stages is high and changes dramatically, with the highest temperature reaching 1100-1200°C.

[0004] The existing method for recovering sensible heat of raw gas from coking is mainly to use heat exchange medium to indirectly recover sensible heat of raw gas to produce steam through coil or water-jacketed raw gas heat exchanger. When the raw gas heat exchanger adopts a spiral coil structure, during the turnover cycle of a coke oven carbonization chamber, the raw gas temperature at the inlet of the raw gas heat exchanger changes dramatically in a short period of time during the coke pushing stage and the coal loading stage. The temperature gradient at the bottom of the raw gas heat exchanger is the largest and the thermal stress is the largest. In addition, due to the gravity of the upper equipment of the raw gas heat exchanger, the dead weight of the main equipment and the gravity of the heat exchange medium, the static force on the bottom of the raw gas heat exchanger is also the largest. Therefore, the bottom of the raw gas heat exchanger is the part with the largest total stress on the entire equipment. In actual production applications, once the total stress of this part exceeds the stress limit that the materials and structures used can withstand, it will cause cracks and damage at the junction of the bottom and the inner tube of the raw gas heat exchanger, and high-temperature raw gas will leak out from the cracks. The leaked high-temperature raw gas will not only cause environmental pollution, but will also immediately burn or corrode the coil when it encounters air, continuing to form local high temperatures. This vicious cycle will eventually cause damage to the raw gas heat exchanger. When the 6.25-meter ramming coke ovens and 7-meter top-loading coke ovens in some domestic coking plants used coil-type raw gas heat exchangers to recover waste heat from raw gas, 40% to 100% of the raw gas heat exchangers were cracked and damaged at the junction of the bottom and the inner tube after running for 3 months to 1 year. The crack-prone parts such as Figure 2 The inner tube and the lower flange welding part are shown. Therefore, how to reduce the bottom stress during the entire coking turnover cycle to eliminate the hidden danger of cracking and damage of the raw gas heat exchanger is a problem that needs to be solved urgently. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned existing background technology, the purpose of the present invention is to provide a prestressed compensation device for reducing the bottom stress in the coil-type raw gas heat exchanger, which can directly and effectively reduce the bottom stress during the entire coking turnover cycle, eliminate the hidden dangers of cracking and damage of the raw gas heat exchanger, and ensure the safe operation of the equipment.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A prestressed compensating device for reducing the bottom stress in a coil-type raw gas heat exchanger, wherein the outer shell of the coil-type raw gas heat exchanger is composed of a sealed upper shell section and a lower shell section, and the prestressed compensating device is arranged on the lower flange of the coil-type raw gas heat exchanger and connected to the upper shell section, and the prestressed compensating device is used to apply an upward thrust to the upper shell section and can adjust the magnitude of the thrust.

[0008] Preferably, the prestressed compensating device comprises a screw, a spring, an upper pad, a lower pad, a lower nut and a force plate, the screw is vertically fixed on the lower flange, the spring is mounted on the screw, the upper pad and the lower pad are respectively mounted on the screw at the upper and lower ends of the spring, the lower nut is threadedly connected on the screw below the lower pad, the force plate is fixed on the outer wall of the upper section of the outer shell, and the lower surface of the force plate is abutted against the upper surface of the upper pad.

[0009] Preferably, a limiting seat is provided at the lower end of the screw rod, a limiting groove is provided on the top surface of the lower flange, and the limiting seat is embedded in the limiting groove and forms a limiting matching relationship therewith.

[0010] Preferably, the force-bearing plate is provided with a slot for the screw to be laterally embedded, a sleeve is sleeved on the screw above the upper pad and is gap-matched with the slot, and an upper nut is threadedly connected to the screw above the sleeve.

[0011] Preferably, a limiting block which forms a lateral limiting cooperation relationship with the sleeve is provided at the lateral outlet of the slot, and a rib plate is connected between the force-bearing plate and the upper section of the shell.

[0012] Preferably, a bellows expansion joint is used to seal between the upper section of the outer shell and the lower section of the outer shell.

[0013] Preferably, the length of the spring compression L = L0-L1 = 0.0065*C*L3, where L0 is the free height of the spring, L1 is the design height between the lower surface of the upper pad and the upper surface of the lower pad, and L3 is the cold height of the raw gas heat exchanger; C is the compression coefficient, which takes a value of 8 to 12 according to the height of the raw gas heat exchanger. When the height of the raw gas heat exchanger is 2 to 3 meters, C takes a value of 8, when the height of the raw gas heat exchanger is 3 to 3.5 meters, C takes a value of 10, and when the height of the raw gas heat exchanger is 3.5 to 4 meters, C takes a value of 12;

[0014] When the compressed length of the spring is L, the corresponding spring thrust is F = 0.5*(G1+G2+G3+G4+G5+G6)±20%, where G1 is the weight of the upper section of the outer shell, G2 is the weight of the upper flange, G3 is the weight of the inner tube, G4 is the weight of the tee, G5 is the weight of the water seal seat and the riser cover, and G6 is the weight of the bridge pipe.

[0015] Preferably, 4-5 hours after the raw gas heat exchanger is installed on the coke oven from a cold state, it is necessary to adjust the height of the lower nut L4 upwards so that the spring returns to the designed height L1 and the spring thrust returns to the designed F value, L4 = 0.0065*L3±10%, L3 is the cold height of the raw gas heat exchanger.

[0016] Preferably, an expansion tank and an explosion-proof membrane are arranged on the upper section of the shell; the explosion-proof membrane has a pressure resistance of P = 0.1*P0±20%, where P0 is the pressure of circulating water at the water inlet; the expansion tank is selected to have an expansion bladder that can withstand temperatures above 150°C, and a volume V = 0.0025*L3±20%, where L3 is the cold height of the raw gas heat exchanger.

[0017] Preferably, the flange bolts of the expansion tank and the explosion-proof membrane are loosened before the raw gas heat exchanger is installed on the coke oven, so that the heat exchanger cavity is connected to the atmosphere through the flange. After installation on the coke oven, wait for 4 to 5 hours after the carbonization chamber is loaded with coal, and then tighten the flange bolts of the expansion tank and the explosion-proof membrane, so that the expansion tank is only subjected to the volume change caused by the gas in the raw gas heat exchanger cavity in the heated state changing with the coking cycle.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] By arranging a prestressed compensating device on the outside of the raw gas heat exchanger, an upward thrust is applied to the upper flange, and the magnitude of this thrust is equal to the weight of the upper shell of the raw gas heat exchanger + the weight of the upper flange + the weight of the inner tube + the weight of the tee + the weight of the water seal seat and the riser cover + the weight of the bridge pipe, so that the pressure on the bottom of the inner tube of the raw gas heat exchanger is zero, and the total pressure on the bottom of the inner tube is reduced. After the raw gas heat exchanger is installed on the coke oven from a cold state and put into operation, the components of the prestressed device are adjusted to restore the thrust of the prestressed device to the design value, so that when the inner tube is subjected to the periodic temperature change of the raw gas of the coke oven, the thrust of the inner tube remains basically unchanged within the range of change of the thermal expansion height, thereby reducing the total stress of the lower part of the inner tube of the coil-type raw gas heat exchanger, eliminating the risk of cracking and damage of the lower part of the inner tube of the raw gas heat exchanger, ensuring the safe operation of the equipment and extending the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a graph showing the change of gas temperature at the inlet of a raw gas heat exchanger in the background technology;

[0021] Figure 2 This is a schematic diagram of the bottom of the existing coil-type raw gas heat exchanger that is prone to cracking;

[0022] Figure 3 This is a schematic diagram of the installation of a coil-type raw gas heat exchanger on a coke oven and its commissioning;

[0023] Figure 4 It is the internal schematic diagram of the coil-type raw gas heat exchanger;

[0024] Figure 5 yes Figure 4 Middle partial enlarged picture;

[0025] Figure 6 yes Figure 4 Top view in the direction of A;

[0026] Figure 7 yes Figure 4 Side view in the direction of B;

[0027] Figure 8 is a schematic diagram of the spring in the free state.

[0028] Figure numerals: 1--coke oven carbonization chamber, 2--raw gas heat exchanger base, 3--coil type raw gas heat exchanger, 4--tee, 5--water seal seat and riser cover, 6--bridge pipe, 7--gas collecting pipe, 8--prestressed compensation device, 301--water inlet, 302--lower section of shell, 303--corrugated expansion joint, 304--coil, 305--inner tube, 306--upper section of shell, 307--explosion-proof membrane, 308--water inlet, 309--lower section of shell, 310--water inlet, 311--water inlet, 312--lower section of shell, 313--water inlet, 314--water inlet, 315--water inlet, 316--lower section of shell, 317--explosion-proof membrane, 318--water inlet, 319--water inlet, 320--water inlet, 321--water inlet, 322--lower section of shell, 323--water inlet, 324--water inlet, 325--water inlet, 326--upper section of shell, 327--explosion-proof membrane, 328--water inlet, 329--water inlet, 330--water inlet, 331--water inlet, 332--water inlet, 333--water inlet, 334--water inlet, 335--water inlet, 336--water inlet, 337--water inlet, 338--water inlet, 339--water inlet, 340--water inlet, 08--expansion tank, 309--water outlet, 310--lower flange, 311--upper flange, 801--limiting groove, 802--limiting seat, 803--lower pad, 804--spring, 805--screw, 806--upper pad, 807--casing, 808--upper nut, 809--force plate, 810--rib plate, 811--limiting block, 812--lower nut, 813--slot. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solution of the present invention, the preferred implementation scheme of the present invention is described below in conjunction with specific embodiments. However, it should be understood that the drawings are only used for exemplary description and cannot be understood as a limitation on this patent. In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationship described in the drawings is only for exemplary description and cannot be understood as a limitation on this patent.

[0030] like Figure 3 As shown, the coke oven carbonization chamber 1 is connected to the base 2 of the raw gas heat exchanger. The raw gas generated in the carbonization chamber flows into the inner tube 305 of the raw gas heat exchanger 3 through the base 2 of the raw gas heat exchanger. In the raw gas heat exchanger 3, it indirectly exchanges heat with circulating water to produce steam to recover the waste heat of the raw gas. The produced steam is used for the coking plant's own production. The raw gas after heat exchange flows to the bridge pipe 6 through the tee 4, and finally gathers into the gas collecting pipe 7, and then enters the gas refining and recovery workshop.

[0031] like Figure 4 and 5As shown, the raw gas heat exchanger is provided with a water inlet 301 and a water outlet 309, which are respectively connected to the heat exchange coil 304 arranged in the heat exchange cavity formed between the inner tube 305, the upper section 306 of the outer shell, and the lower section 302 of the outer shell; the corrugated expansion joint 303 is used to seal between the upper section 306 of the outer shell and the lower section 302 of the outer shell, so as to isolate the external air from entering the cavity to oxidize and corrode the coil; the expansion tank 308 and the explosion-proof membrane 307 are arranged outside the upper section of the outer shell, and the explosion-proof membrane 307 plays a protective role when the heat exchange coil is damaged and explodes, and the circulating water enters the cavity to be heated and vaporized into steam, and the explosion-proof membrane 307 bursts when the pressure exceeds the explosion-proof membrane 307, and the steam and water are discharged from the raw gas heat exchanger; the expansion tank 308 is used to absorb the volume change of the gas in the cavity between the inner tube and the outer shell when the raw gas temperature changes, so as to prevent the gas pressure in the cavity from fluctuating too much and damaging the equipment.

[0032] like Figure 4-8 As shown, the prestressed compensating device 8 includes a screw 805, a spring 804, an upper pad 806, a lower pad 803, a lower nut 812 and a force plate 809. The screw 805 is vertically fixed on the lower flange 310, and the spring 804 is mounted on the screw 805. The upper pad 806 and the lower pad 803 are respectively mounted on the screw 805 at the upper and lower ends of the spring 804. The lower nut 812 is threadedly connected to the screw 805 below the lower pad 803. The force plate 809 is fixed on the outer wall of the upper section 306 of the shell, and the lower surface of the force plate 809 is against the upper surface of the upper pad 806.

[0033] Specifically, the force plate 809 is provided with a slot 813 for the screw 805 to be laterally embedded, the screw 805 above the upper pad 806 is sleeved with a sleeve 807 and is clearance-matched with the slot 813, and the screw 805 above the sleeve 807 is threadedly connected with an upper nut 808. A limit block 811 is provided at the lateral exit of the slot 813 to form a lateral limit-matching relationship with the sleeve 807, and a rib plate 810 is connected between the force plate 809 and the upper section 306 of the housing. A limit seat 802 is provided at the lower end of the screw 805, and a limit groove 801 is provided on the top surface of the lower flange 310, and the limit seat 802 is embedded in the limit groove 801 and forms a limit-matching relationship therewith.

[0034] like Figure 7 and 8 As shown, the free height of the spring 804 is L0. Before assembling the equipment, the upper nut 808 is adjusted to be compressed to a height slightly less than L1, and then inserted into the lower limit groove 801 and the U-shaped groove 813 of the force plate 809, and the limit block 811 is fixed. Then the upper nut 808 is loosened upward to make the upper pad 806 fit to the lower surface of the force plate 809, and the upper nut 808 is continued to be loosened to make the lower surface of the upper nut 808 and the upper surface of the sleeve 806 spaced by a length of L2, L2 ≥ 0.0065 * L3 + 10, where L3 is the cold height of the raw gas heat exchanger, in mm.

[0035] The compressed length of the spring 804 is L=L0-L1=0.0065*C*L3, where L0 is the free height of the spring 804, L1 is the design height between the lower surface of the upper pad 806 and the upper surface of the lower pad 803, and L3 is the cold height of the raw gas heat exchanger; C is the compression coefficient, which is 8 to 12 according to the height of the raw gas heat exchanger. When the height of the raw gas heat exchanger is 2 to 3 meters, C is 8, when the height of the raw gas heat exchanger is 3 to 3.5 meters, C is 10, and when the height of the raw gas heat exchanger is 3.5 to 4 meters, C is 12;

[0036] When the compressed length of the spring is L, the corresponding spring thrust is F=0.5*(G1+G2+G3+G4+G5+G6)±20%, wherein G1 is the weight of the upper section 306 of the outer shell, G2 is the weight of the upper flange 311, G3 is the weight of the inner tube 305, G4 is the weight of the tee 4, G5 is the weight of the water seal seat and the riser cover 5, and G6 is the weight of the bridge pipe 6.

[0037] When the raw gas heat exchanger of the present invention is installed on the coke oven from a cold state for 4-5 hours, that is, after the equipment is evenly heated to a normal hot working state, the height of the raw gas heat exchanger will increase, and the spring height of the prestressed compensating device 8 will change. At this time, it is necessary to adjust the height of the lower nut 812 by L4 upward to restore the spring to the designed height L1, and the spring thrust is restored to the designed F value, L4 = 0.0065*L3 ± 10%, L3 is the cold height of the raw gas heat exchanger.

[0038] An expansion tank 308 and an explosion-proof membrane 307 are arranged on the upper section 306 of the shell; the withstand pressure of the explosion-proof membrane 307 is P=0.1*P0±20%, where P0 is the pressure of circulating water at the water inlet; the expansion tank 308 is an expansion tank whose expansion bag can withstand temperatures above 150°C, and the volume V is selected according to the height of the riser heat exchanger: V=0.0025*L3±20%, where L3 is the cold height of the raw gas heat exchanger.

[0039] Before the raw gas heat exchanger is installed on the coke oven, the flange bolts of the expansion tank 308 and the explosion-proof membrane 307 are loosened to allow the heat exchanger cavity to communicate with the atmosphere through the flange. After installation on the coke oven, wait for 4-5 hours after the carbonization chamber is loaded with coal, and then tighten the flange bolts of the expansion tank 308 and the explosion-proof membrane 307 to allow the expansion tank 308 to only be subjected to the volume change caused by the gas in the raw gas heat exchanger cavity in the heated state changing with the coking cycle.

[0040] A prestressed compensating device of the present invention is used in the design, manufacture, installation and commissioning of a coil-type raw gas heat exchanger of a coke oven raw gas waste heat utilization device:

[0041] Two prestressed compensating devices 8 are arranged outside the raw gas heat exchanger 3 along the center line of the coke oven to apply an upward thrust to the upper flange. The magnitude of this thrust is equal to the weight of the upper section 306 of the shell of the raw gas heat exchanger 3 + the weight of the upper flange 311 + the weight of the inner tube 305 + the weight of the tee 4 + the weight of the water seal seat and the riser cover 5 + the weight of the bridge pipe 6, so that the pressure on the bottom of the inner tube 305 of the raw gas heat exchanger 3 is zero, thereby reducing the total pressure on the bottom of the inner tube 305.

[0042] When the raw gas heat exchanger 3 of the present invention is installed on the coke oven from a cold state for 5 hours, that is, after the equipment is evenly heated to a normal hot working state, the height of the raw gas heat exchanger will increase, and the height of the spring 804 of the prestressed compensating device 8 will change. At this time, it is necessary to adjust the lower nut 812 upward by a height to restore the spring 804 to the designed height, so that when the inner tube 305 of the raw gas heat exchanger is subjected to the periodic temperature change of the raw gas of the coke oven, the thrust of the inner tube 305 remains basically unchanged within the range of the change of the thermal expansion height, thereby reducing the total stress in the lower part of the inner tube 305 of the coil-type raw gas heat exchanger, eliminating the risk of cracking and damage in the lower part of the inner tube 305 of the raw gas heat exchanger, ensuring the safe operation of the equipment and extending the service life of the equipment.

[0043] Application examples:

[0044] The double-helix raw gas heat exchanger designed with a prestressed thermal expansion compensation raw gas heat exchanger of the present invention is used to produce 2.5MPa steam in a 6-meter and 7-meter top-mounted coke oven raw gas waste heat utilization project in a coking plant. The application example effectively eliminates the total expansion stress at the bottom of the coil-type raw gas heat exchanger caused by the drastic change in raw gas temperature, prevents the bottom of the coil-type raw gas heat exchanger from cracking and damage, ensures the safe operation of the raw gas heat exchanger and the coke oven, and improves the service life of the raw gas heat exchanger.

[0045] According to the description and drawings of the present invention, those skilled in the art can easily manufacture or use the prestressed compensating device of the present invention for reducing the bottom stress in a coil-type raw gas heat exchanger, and can produce the positive effects described in the present invention.

[0046] Unless otherwise specified, in the present invention, the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicating orientation or positional relationships are based on the orientation or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the orientation or positional relationship in the present invention are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood in conjunction with the drawings and according to specific circumstances.

[0047] Unless otherwise clearly specified and limited, in the present invention, the terms "disposed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A prestressed compensating device for reducing the bottom stress of a coil-type raw gas heat exchanger, characterized in that: The shell of the coil-type raw gas heat exchanger (3) is composed of a sealed upper shell section (306) and a lower shell section (302); the prestress compensation device (8) is arranged on the lower flange (310) of the coil-type raw gas heat exchanger (3) and connected to the upper shell section (306); the prestress compensation device (8) is used to apply an upward thrust to the upper shell section (306) and can adjust the magnitude of the thrust; the inner tube (305) of the coil-type raw gas heat exchanger (3) is welded to the lower flange (310); The prestressed compensating device (8) comprises a screw (805), a spring (804), an upper pad (806), a lower pad (803), a lower nut (812) and a force plate (809), wherein the screw (805) is vertically fixed on the lower flange (310), the spring (804) is sleeved on the screw (805), the upper pad (806) and the lower pad (803) are sleeved on the screw (805) at the upper and lower ends of the spring (804), respectively, the lower nut (812) is threadedly connected on the screw (805) below the lower pad (803), the force plate (809) is fixed on the outer wall of the upper section (306) of the housing, and the lower surface of the force plate (809) is against the upper surface of the upper pad (806); The compressed length of the spring L = L0-L1 = 0.0065*C*L3, where L0 is the free height of the spring, L1 is the design height between the lower surface of the upper pad and the upper surface of the lower pad, and L3 is the cold height of the coil-type gas heat exchanger; C is the compression coefficient, which is determined according to the height of the coil-type gas heat exchanger. When the height of the coil-type gas heat exchanger is 2 to 3 meters, C is 8; when the height of the coil-type gas heat exchanger is 3 to 3.5 meters, C is 10; when the height of the coil-type gas heat exchanger is 3.5 to 4 meters, C is 12; When the length of the spring compression is L, the corresponding spring thrust is F=0.5*(G1+G2+G3+G4+G5+G6)±20%, wherein G1 is the weight of the upper section (306) of the outer shell, G2 is the weight of the upper flange (311), G3 is the weight of the inner tube (305), G4 is the weight of the tee (4), G5 is the weight of the water seal seat and the riser cover (5), and G6 is the weight of the bridge pipe (6).

2. The prestressed compensating device for reducing the bottom stress of a coil-type raw gas heat exchanger according to claim 1, characterized in that: A limiting seat (802) is provided at the lower end of the screw rod (805), a limiting groove (801) is provided on the top surface of the lower flange (310), and the limiting seat (802) is embedded in the limiting groove (801) and forms a limiting matching relationship therewith.

3. The prestressed compensating device for reducing the bottom stress of a coil-type raw gas heat exchanger according to claim 1, characterized in that: The force-bearing plate (809) is provided with a slot (813) for the screw (805) to be laterally embedded, the screw (805) above the upper pad (806) is sleeved with a sleeve (807) and is clearance-matched with the slot (813), and the screw (805) above the sleeve is threadedly connected with an upper nut (808).

4. The prestressed compensating device for reducing the bottom stress of a coil-type raw gas heat exchanger according to claim 3, characterized in that: A limiting block (811) is provided at the lateral exit of the slot (813) and forms a lateral limiting cooperation relationship with the sleeve (807), and a rib plate (810) is connected between the force-bearing plate (809) and the upper section (306) of the housing.

5. The prestressed compensating device for reducing the bottom stress of a coil-type raw gas heat exchanger according to claim 1, characterized in that: A bellows expansion joint (303) is used to seal between the upper shell section (306) and the lower shell section (302).

6. The prestressed compensating device for reducing the bottom stress of a coil-type raw gas heat exchanger according to claim 1, characterized in that: When the coil-type raw gas heat exchanger (3) is installed on the coke oven from a cold state for 4-5 hours, the lower nut (812) needs to be adjusted upward by a height of L4 so that the spring (804) returns to the designed height L1 and the thrust of the spring (804) returns to the designed F value, L4 = 0.0065*L3 ± 10%, where L3 is the cold state height of the coil-type raw gas heat exchanger.

7. The prestressed compensating device for reducing the bottom stress of a coil-type raw gas heat exchanger according to claim 1, characterized in that: An expansion tank (308) and an explosion-proof membrane (307) are arranged on the upper section (306) of the shell; the explosion-proof membrane (307) has a withstand pressure of P=0.1*P0±20%, where P0 is the pressure of circulating water at the water inlet (301); the expansion tank (308) is an expansion tank whose expansion bladder can withstand a temperature above 150°C, and a volume V=0.0025*L3±20%, where L3 is the cold height of the coil-type raw gas heat exchanger.

8. The prestressed compensating device for reducing the bottom stress of a coil-type raw gas heat exchanger according to claim 7, characterized in that: Before the coil-type raw gas heat exchanger (3) is installed on the coke oven, the flange bolts of the expansion tank (308) and the explosion-proof membrane (307) are loosened to allow the heat exchanger cavity to communicate with the atmosphere through the flange. After installation on the coke oven, after the carbonization chamber is loaded with coal for 4-5 hours, the flange bolts of the expansion tank (308) and the explosion-proof membrane (307) are tightened again to allow the expansion tank (308) to only be subjected to the volume change caused by the gas in the cavity of the coil-type raw gas heat exchanger (3) in the heated state as the coking cycle changes.

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