CN207212680U - Solar energy thermal-power-generating high-temperature long-shaft pump for liquid salts - Google Patents

Abstract

The utility model discloses a high-temperature long-axis molten salt pump for solar thermal power generation. The front end of the component is provided with a suction section, and the front end of the suction section is provided with a cascade filter. The front end of the supporting pipe of the structure is connected and fixed; the end of the supporting pipe of the supporting and damping structure is connected and fixed with the bottom of the outlet section of the fluid sealing structure through a flange plate. The high-temperature long-axis molten salt pump for solar thermal power generation described in the utility model is designed in the form of central outflow to ensure uniform thermal expansion under high temperature conditions. Reliable fluid sealing design, reasonable heat dissipation structure and flange expansion joint vibration reduction configuration and other solutions ensure the safe, reliable and efficient operation of the high-temperature long-axis molten salt pump for solar thermal power generation, and meet various performance indicators at the same time.

Description

High temperature long axis molten salt pump for solar thermal power generation

technical field

The utility model relates to the field of solar energy industrial equipment, in particular to a high-temperature long-axis molten salt pump used in a cold/hot molten salt storage tank system of a solar thermal power station.

Background technique

In a thermal island of a solar thermal power station that uses molten salt as heat storage medium or heat transfer medium, the molten salt pump configured with the molten salt storage tank is one of the most critical equipment. The liquid level of molten salt between cold and hot molten salt storage tanks can be alternately changed through the molten salt pump to meet the needs of heat storage or heat transfer.

The technical deficiencies of conventional molten salt pumps:

First: The maximum operating temperature of the tower-type technical route in the power station is 565 ° C, while the operating temperature of conventional molten salt pumps is up to 400 ° C, which are mostly used in melamine plants in the chemical industry, alumina preparation and other fields.

Second: The submerged depth of molten salt pumps used in power stations is generally about 16m, while the submerged depth of conventional molten salt pumps is within 5 meters. Too long shafting poses a safety hazard to smooth operation.

Third: The conventional molten salt pump structure is in the form of API610VS4, generally with single-stage or two-stage impellers, which cannot meet the high-lift working conditions of tower heat absorbers.

Fourth: The location of the power station is generally located in the alpine region of Northwest China. The problem of freezing and blocking of high melting point molten salt has become a technical difficulty in the safe operation of molten salt pumps.

Fifth: Conventional molten salt pumps usually use screw seals, but for the safety and device specificity of molten salt pumps used in power stations, screw seals are no longer competent.

Sixth: Most of the power station sites are located in areas with rich sunlight resources and little rain, so the traditional water circulation bearing cooling device is not suitable for such environments.

Seventh: Displacement changes caused by high temperature or vibration at the flange of large molten salt storage tanks used in power stations will bring potential molten salt pump vibration failures.

Eighth: The power station considers the maximum utilization rate of molten salt in the molten salt storage tank, and requires the pump to operate stably at a low liquid level submersion depth, which may lead to a decrease in the suction performance of the molten salt pump and cause cavitation.

Contents of the invention

According to the above-mentioned technical problems, a high-temperature long-axis molten salt pump for solar thermal power generation is provided to solve the existing molten salt pump technology. The shaft system is too long to cause safety hazards in smooth operation, and the screw sealing effect is insufficient. Molten salt pumps are prone to vibration failures and other shortcomings. The technical means adopted in the utility model are as follows:

A high-temperature long-axis molten salt pump for solar thermal power generation, including a pump shaft, and the pump shaft is sequentially provided with a hydraulic component, a support damping structure, a fluid sealing structure, and a bearing cooling device from bottom to top; the front end of the hydraulic component is provided with The suction section, the front end of the suction section is provided with a cascade filter, the end of the hydraulic component is provided with a final-stage diversion shell, and the end of the final-stage diversion shell is the same as the front end of the support tube of the support vibration-damping structure The connection is fixed; the end of the support tube of the support and damping structure is connected and fixed with the bottom of the outlet section of the fluid sealing structure through a flange plate, and the top of the outlet section is connected and fixed with a bearing bracket through a flange plate; the bearing cooling The device is installed in the bearing bracket.

Preferably, the hydraulic components include: a suction section, an impeller, an impeller snap ring, a guide casing and a sliding bearing assembly; the impeller is fixed on the pump shaft through an impeller key, and the impeller includes a primary impeller and at least one secondary The impeller, so that the first-stage impeller and at least one secondary impeller are positioned step by step on the outer wall of the pump shaft through the impeller snap ring; The guide shell and at least one last-stage guide shell are arranged on the outside of the first-stage impeller and at least one secondary impeller; the first-stage guide shell and at least one final-stage guide shell are provided with a sliding bearing assembly, and the The mating surface of the sliding bearing assembly is in the form of a spiral groove to enhance self-lubricating performance.

Preferably, the first-stage flow guide shell and at least one last-stage flow guide shell are positioned and connected through flange seams, so that the first-stage impeller is matched with the first-stage flow guide shell, and the secondary impeller is matched with the last-stage flow guide shell. .

Preferably, the suction section is provided with an inducer, and the inducer is fixed on the pump shaft through a key to improve the suction performance of the pump; impeller mouth rings are mounted on both sides of the impeller, and casings are mounted on both sides of the guide shell. mouth ring.

Preferably, the support and damping structure includes: a pump bottom plate, a storage tank flange, a support pipe, a flanged bellows expansion joint, and a foundation; the outside of the pump bottom plate is fixed on the foundation, and a storage tank flange is arranged below, The flange top of the storage tank and the inner side of the pump bottom plate are provided with flanged bellows expansion joints for shock absorption; the support pipe is connected and fixed with the vertical support pipe through the flange plate, There is a support frame.

Preferably, the pump shaft is a multi-section shaft connection method, and the multi-section pump shaft is fixedly connected by a shaft connection assembly.

Preferably, the fluid sealing structure includes: a bearing bracket, a packing seal, a nitrogen gas inlet, a liquid outlet pipeline, a throat bushing, a discharge pipeline, an outlet section, a nitrogen isolation chamber and an insulation layer; the outlet section is provided with Nitrogen isolation chamber, the nitrogen isolation chamber isolates the section of the pump shaft from the liquid outlet pipeline of the outlet section, the bottom of the nitrogen isolation chamber is provided with a throat bushing, and the throat bushing is installed on the outer wall of the pump shaft The upper part of the nitrogen isolation chamber is connected with a nitrogen inlet, and the lower part is provided with a discharge pipeline, so that the nitrogen isolation chamber is connected with the storage tank; the top of the outlet section is provided with a packing seal, and the packing seal is filled in the pump shaft and the pump shaft. Between the core holes of the blue plate, the bottom of the bearing bracket is provided with an insulating layer.

Preferably, the bearing cooling device includes: an upper fan cover, an upper fan, a bearing housing, an oil hole, an oil retaining sleeve, an air induction groove, a lower fan, a lower fan cover, a bearing sleeve and a bearing; The flange plate is equipped with a bearing box, and a bearing and a bearing sleeve are arranged in the bearing box, the bearing is arranged on the upper part of the bearing sleeve, and an oil retaining sleeve is arranged on the outer side of the lower part of the bearing sleeve, and in the bearing box An oil hole connected to the top of the bearing is provided; an upper fan and a lower fan are respectively installed on the pump shafts on the upper and lower sides of the bearing box, and an upper fan cover and a lower fan cover are respectively installed on the outer sides of the upper fan and the lower fan.

Preferably, the bearing is an angular contact ball bearing; the bearing housing is processed with air-introducing grooves for increasing the cooling area.

Preferably, the high-temperature molten salt area of the outlet section is wrapped with a ceramic fiber blanket, and covered with moisture-proof materials and metal sheets for binding and fixing.

Compared with the prior art, the solar thermal power generation high-temperature long-axis molten salt pump described in the utility model has the following advantages:

1. The solar thermal power generation high-temperature long-axis molten salt pump described in the utility model has a suction section at the front end of the hydraulic component, and a cascade filter is provided at the front end of the suction section, considering the maximum utilization rate of the molten salt in the molten salt storage tank , to maximize the power generation, the submerged depth between the pump suction inlet and the bottom of the tank should be reduced as much as possible, and a cascade filter should be installed on the side of the suction section to prevent swirl flow and vortex in the water due to too small suction distance, and ensure It has a stable flow state. In addition, according to the characteristics of specific working conditions, it is considered to configure a high-efficiency inducer before the suction impeller to improve suction performance and meet low cavitation conditions.

2. In the high-temperature long-axis molten salt pump for solar thermal power generation described in the utility model, a sliding bearing assembly is arranged at the first-stage diversion shell and at least one last-stage diversion shell. For working conditions with a depth of 16m or longer, multi-point sliding bearing support is set between the shell and the impeller rotor, and the surface of the dynamic and static friction pairs adopts surface welding technology to improve hardness and wear resistance. The design of the spiral groove realizes the condition of sufficient lubrication. During the operation, the small gap of the friction pair forms a rigid liquid film, which plays a role in stabilizing the entire rotor and ensuring its safe and reliable operation.

3. In the high temperature long-axis molten salt pump for solar thermal power generation described in this utility model, the pump shaft is a multi-section shaft connection method, and the multi-section pump shaft is fixedly connected by the shaft connection assembly. Considering the crystallization of molten salt during disassembly and maintenance, the pump The multi-section shafting connection method is fixed by split shaft assembly, which improves the convenience of disassembly.

4. In the solar thermal power generation high-temperature long-axis molten salt pump described in the utility model, the bottom of the nitrogen isolation chamber is provided with a throat bushing, and the throat bushing is installed on the outer wall of the pump shaft, and the fluid sealing system adopts a reverse spiral throat bushing. Control the leakage of molten salt and reduce volume loss. The molten salt passing through the throat bushing returns to the storage tank along the discharge line. During operation, the isolation chamber needs to be continuously injected with isolation and lubricating nitrogen to keep the molten salt isolated from the atmosphere and reduce Heat conduction to the bearing side, under the action of the packing seal, a stable pressure chamber is formed in the nitrogen isolation chamber, truly realizing zero leakage of molten salt.

5. In the high-temperature long-axis molten salt pump for solar thermal power generation described in this utility model, an oil retaining sleeve is provided on the outer side of the lower part of the bearing sleeve, and an oil hole connected to the top of the bearing is provided in the bearing box; the pump shaft on the upper and lower sides of the bearing box The upper fan and the lower fan are installed respectively. Considering the particularity of the site selection of the power station, a bearing cooling device combining oil cooling and fan cooling is designed to replace the water circulation bearing cooling and reduce the consumption of water resources system. The bearing cooling device uses the rotation of the bearing sleeve to provide the circulation power of the lubricating oil, so that the lubricating oil is lifted to the upper part of the bearing, and the self-weight of the lubricating oil is used to realize the lubrication of the bearing. Both the bearing side and the oil chamber side are equipped with fans to control the temperature rise of the bearing within the standard range and maintain a stable state.

6. For the solar thermal power generation high-temperature long-axis molten salt pump described in the utility model, the top of the storage tank flange and the inner side of the bottom plate of the pump are provided with flange-type bellows expansion joints for shock absorption, which will effectively absorb the large-scale molten salt storage for power stations. The mounting surface of the tank flange is displaced axially or radially due to high temperature or vibration. In addition, an insulating and heat-preserving shell is arranged around the flange bellows expansion joint to reduce heat loss.

Description of drawings

Below in conjunction with accompanying drawing and specific embodiment, the utility model is described in further detail.

Fig. 1 is a schematic diagram of the overall structure of the utility model.

Fig. 2 is a partially enlarged view of the hydraulic component of the present invention.

Fig. 3 is a partially enlarged view of the fluid sealing structure of the present invention.

Fig. 4 is a partially enlarged view of the supporting and damping structure of the present invention.

Fig. 5 is a partially enlarged view of the bearing cooling device of the present invention.

Among them: 1. Upper fan cover, 2. Upper fan, 3. Bearing box, 4. Oil hole, 5. Oil retaining sleeve, 6. Air induction groove, 7. Lower fan, 8. Bearing bracket, 9. Packing seal , 10. Nitrogen inlet, 11. Outlet pipeline, 12. Pump bottom plate, 13. Throat bushing, 14. Storage tank flange, 15. Support pipe, 16. Pump shaft, 17. Final diversion shell, 18. Impeller snap ring, 19. First-stage impeller, 20. Suction section, 21. Cascade filter, 22. Inducer, 23. Impeller mouth ring, 24. Shell mouth ring, 25. First-stage diversion shell , 26, impeller key, 27, sliding bearing assembly, 28, shaft assembly, 29, support frame, 30, discharge pipeline, 31, flanged bellows expansion joint, 32, foundation, 33, outlet section, 34 , nitrogen isolation cavity, 35, insulation layer, 36, lower fan cover, 37, axle sleeve, 38, bearing.

Detailed ways

As shown in Figures 1 to 5, a high-temperature long-axis molten salt pump for solar thermal power generation includes a pump shaft 16, and the pump shaft 16 is sequentially provided with hydraulic components, a support and damping structure, a fluid sealing structure, and a bearing from bottom to top. Cooling device; the front end of the hydraulic component is provided with a suction section 20, and the front end of the suction section 20 is provided with a cascade filter 21 to avoid backflow and vortex in water at the entrance. The end of the hydraulic component is provided with a final diversion shell 17, and the end of the last stage diversion shell 17 is connected and fixed with the front end of the support tube 15 of the support vibration damping structure; the support tube 15 of the support vibration damping structure The end is connected and fixed with the bottom of the outlet section 33 of the fluid-tight structure through a flange plate, and the top of the outlet section 33 is connected and fixed with a bearing bracket 8 through a flange plate; the bearing cooling device is installed in the bearing bracket 8 .

The hydraulic components include: suction section 20, impeller, impeller snap ring 18, guide casing and sliding bearing assembly 27; the impeller is fixed on the pump shaft 16 through the impeller key 26, and the impeller includes the first stage impeller 19 and At least one secondary impeller, the primary impeller 19 and the at least one secondary impeller are positioned step by step on the outer wall of the pump shaft 16 through the impeller snap ring 18 .

The induction casing includes a first-stage induction casing 25 and at least one last-stage induction casing 17, and the first-stage induction casing 25 and at least one final-stage induction casing 17 are correspondingly arranged on the first-stage impeller 19 and at least one final-stage induction casing. The outer side of a secondary impeller; the first-stage guide shell 25 and at least one last-stage guide shell 17 are provided with a sliding bearing assembly 27, and the mating surface of the sliding bearing assembly 27 is in the form of a spiral groove to enhance self-lubricating performance. For working conditions with a submerged depth of 16m or longer, the sliding bearing assembly 27 of the submerged multi-point support part adopts surface surfacing technology and a fully lubricated structure in the form of a spiral groove.

The first-stage diversion shell 25 and at least one final-stage diversion shell 17 are positioned and connected through flange seams, so that the first-stage impeller 19 is matched with the first-stage diversion shell 25, and the secondary impeller is guided with the rest of the final stage. The shell 17 matches the setting.

The suction section 20 is provided with an inducer 22, and the inducer 22 is fixed on the pump shaft 16 through keys to improve pump suction performance.

Both sides of the impeller are inlaid with impeller mouth rings 23, and both sides of the guide shell are inlaid with housing mouth rings 24, so that the impeller mouth ring 23 and the housing mouth ring 24 form a dynamic and static friction pair. The small gap reduces volume loss, and also has a certain supporting effect on the entire rotor. And hard alloy is surfacing on the surface of the gap between the impeller mouth ring 23 and the housing mouth ring 24 to improve hardness and wear resistance.

The support and damping structure includes: a pump bottom plate 12, a storage tank flange 14, a support pipe 15, a flanged bellows expansion joint 31 and a foundation 32; the outside of the pump bottom plate 12 is fixed on the foundation 32, and a The storage tank flange 14, the top of the storage tank flange 14 and the inner side of the pump bottom plate 12 are provided with flanged bellows expansion joints 31 for shock absorption to realize the shock absorption function.

The support tube 15 is connected and fixed with the vertically arranged support tube 15 through the flange plate, and the support frame 29 is arranged inside the support tube 15, and the support frame 29 and the support tube 15 are built-in and fixed by welding, reducing the axial fit Size deviation.

The pump shaft 16 is a multi-segment shaft connection method, which is fixedly connected by a shaft connection assembly 28 to form a multi-segment pump shaft. The connection mode of the multi-section shafting of the pump is fixed by a split shaft assembly, and the shaft assembly 28 includes a shaft sleeve, a shaft snap ring, a connecting key, and the like.

The fluid sealing structure includes: a bearing bracket 8, a stuffing seal 9, a nitrogen gas inlet 10, a liquid outlet pipeline 11, a throat bushing 13, a discharge pipeline 30, an outlet section 33, a nitrogen isolation chamber 34 and an insulation layer 35; The outlet section 33 is provided with a nitrogen isolation chamber 34, which isolates the pump shaft 16 of this section from the liquid outlet pipeline 11 of the outlet section 33, and the bottom of the nitrogen isolation chamber 34 is provided with a throat liner Sleeve 13, the throat bushing 13 is installed on the outer wall of the pump shaft 16.

The nitrogen gas inlet 10 is connected to the upper part of the nitrogen gas isolation chamber 34, and the drain pipe 30 is arranged at the lower part, so that the nitrogen gas isolation chamber 34 is connected with the storage tank, and pressurized nitrogen gas is introduced through the nitrogen gas inlet 10 for isolation and lubrication.

The top of the outlet section 33 is provided with a stuffing seal 9 , and the stuffing seal 9 is filled between the pump shaft 16 and the core hole of the flange plate, and the bottom of the bearing bracket 8 is provided with an insulating layer 35 .

The outlet section is designed with a reliable fluid sealing structure, including packing seal, nitrogen isolation and lubrication, and double-branch salt discharge pipeline. The high-temperature molten salt area of the outlet section is wrapped with a ceramic fiber blanket, and covered with moisture-proof materials and metal sheets for binding and fixing.

The molten salt is divided into two parts at the position of the throat liner 13 , most of which are discharged through the outlet pipeline 11 , and only a small part passes through the throat liner 13 and returns to the storage tank along the discharge line 30 .

A packing seal 9 is arranged on the top of the outlet section 33 to maintain a stable pressure area in the nitrogen isolation chamber 34 . An insulating layer 35 is provided between the packing seal 9 and the bearing bracket 8 to further prevent high temperature heat from being transmitted to the bearing side.

The bearing cooling device includes: an upper fan cover 1, an upper fan 2, a bearing housing 3, an oil hole 4, an oil retaining sleeve 5, an air induction groove 6, a lower fan 7, a lower fan cover 36, a bearing sleeve 37 and a bearing 38; the bearing housing 3 is installed through the flange plate in the bearing bracket 8, the bearing housing 3 is provided with a bearing 38 and a bearing sleeve 37, the bearing 38 is arranged on the upper part of the bearing housing 37, and the bearing housing 3 An oil deflecting sleeve 5 is arranged outside the lower part of the bearing sleeve 37 , and an oil hole 4 communicating with the top of the bearing 38 is arranged inside the bearing housing 3 .

An upper fan 2 and a lower fan 7 are respectively installed on the pump shafts 16 on the upper and lower sides of the bearing housing 3 , and an upper fan cover 1 and a lower fan cover 36 are respectively installed on the outer sides of the upper fan 2 and the lower fan 7 .

The bearing 38 is an angular contact ball bearing; the bearing housing 3 is processed with an air induction groove 6 for increasing the cooling area.

The driving end of the pump is designed with a pair of angular contact ball bearings to bear radial force and residual axial force. The surrounding lubricating oil is powered by the rotation of the bearing sleeve 37, the lifting lubricating oil flows from the oil hole 4 to the top of the bearing 38, and the bearing is lubricated by gravity, and the lubricated hot oil falls back into the oil pool. In order to prevent the hot oil from being sucked by the bearing sleeve 37 again after falling, the oil retaining sleeve 5 is designed to form an isolated area, and the hot oil exchanges heat with the bearing housing 3 .

The air volume generated by the upper fan 2 is aligned with the air guide groove 6 for forced cooling, and the upper fan cover 1 forms a good cooling area to increase the heat exchange area. The lower fan 7 and the lower fan cover 36 form a cooling system to cool the lubricating oil side in the bearing housing.

The bearing parts are located between the bearing bracket and the outlet section, including bearings, fans, bearing boxes, bearing glands, etc., and the bearing parts are equipped with a unique bearing oil extraction circuit and a reliable double fan cooling method.

The support tube 15 and the internal support frame 29 are combined into one body by welding to achieve compact structure and form an integrated support frame.

For the high-temperature long-axis molten salt pump for solar thermal power generation described in the utility model, for the material selection of the molten salt pump with a service temperature of 565°C, factors such as corrosion resistance, high temperature resistance strength, and high temperature oxidation resistance are mainly considered. In addition, heat-resistant steel with the same or close thermal expansion coefficient should be used as much as possible, and the influence of thermal expansion can be balanced by the material itself to prevent irregular thermal deformation at high temperature.

The heat-resistant steel is 347H stainless steel, which has good high-temperature mechanical properties. Mainly due to the addition of stabilizing element niobium to the stainless steel. The combination of niobium and carbon is much stronger than that of chromium. They form the compound NbC before chromium and carbon, avoiding the formation of Cr23C6 and the appearance of chromium-poor bands, thereby avoiding intergranular corrosion.

The high-temperature long-axis molten salt pump for solar thermal power generation described in the utility model is designed in the form of API610VS1. Heater high lift condition, while other performance indicators of VS1 form are better than VS4 form.

In the high-temperature long-axis molten salt pump for solar thermal power generation described in the utility model, the high-temperature molten salt area of the outlet section is circularly wound with ceramic fiber blankets, covered with moisture-proof materials and metal sheets for binding and fixing, and solves the problem of freezing of high-melting point molten salts. blocking problem. The main focus is to effectively prevent the medium from freezing and blockage of the shaft system when the ambient temperature of the pump’s flow-through components drops.

Aiming at the usage characteristics of high-temperature long-axis pumps in solar thermal power stations, it effectively solves the technical deficiencies of conventional molten salt pumps, and has the characteristics of stable operation, safety and reliability, and long service life. Considering the reliability of technology, it can be popularized and applied on a large scale.

It is designed in the form of central outflow to ensure uniform thermal expansion under high temperature conditions. Reliable fluid sealing design, reasonable heat dissipation structure and flange expansion joint vibration reduction configuration and other solutions ensure the safe, reliable and efficient operation of the high temperature long-axis molten salt pump for solar thermal power generation, and meet various performance indicators at the same time. The high-temperature long-axis molten salt pump for solar thermal power generation described in the utility model is used for a pump for a cold/hot molten salt storage tank system of a solar thermal power station.

The above is only a preferred embodiment of the utility model, but the scope of protection of the utility model is not limited thereto. Any equivalent replacement or change of the new technical solution and its inventive concept shall be covered by the protection scope of the present utility model.

Claims (10)

1. A high-temperature long-axis molten salt pump for solar thermal power generation, characterized in that it includes a pump shaft, and the pump shaft is sequentially provided with hydraulic components, a support damping structure, a fluid sealing structure and a bearing cooling device from bottom to top; The front end of the hydraulic component is provided with a suction section, the front end of the suction section is provided with a cascade filter, and the end of the hydraulic component is provided with a final diversion shell, the end of which is the same The front end of the support pipe supporting the vibration-damping structure is connected and fixed; The end of the support tube of the support and damping structure is connected and fixed with the bottom of the outlet section of the fluid sealing structure through a flange plate, and the top of the outlet section is connected and fixed with a bearing bracket through a flange plate; The bearing cooling device is installed in the bearing bracket. 2. The high-temperature long-axis molten salt pump for solar thermal power generation according to claim 1, characterized in that: The hydraulic components include: a suction section, an impeller, an impeller snap ring, a guide casing and a sliding bearing assembly; The impeller is fixed on the pump shaft through the impeller key, and the impeller includes a primary impeller and at least one secondary impeller, so that the primary impeller and at least one secondary impeller are positioned step by step on the outer wall of the pump shaft through the impeller snap ring ; The induction casing includes a first-stage induction casing and at least one last-stage induction casing, and the first-stage induction casing and at least one final-stage induction casing are correspondingly arranged outside the first-stage impeller and at least one secondary impeller ; A sliding bearing assembly is arranged at the first-stage diversion shell and at least one last-stage diversion shell, and the mating surface of the sliding bearing assembly is in the form of a spiral groove. 3. The high-temperature long-axis molten salt pump for solar thermal power generation according to claim 2, characterized in that: The first-stage diversion shell and at least one final-stage diversion shell are positioned and connected through flange seams, so that the first-stage impeller is matched with the first-stage diversion shell, and the secondary impeller is matched with the remaining final-stage diversion shells. 4. The high-temperature long-axis molten salt pump for solar thermal power generation according to claim 2, characterized in that: The suction section is provided with an inducer, and the inducer is fixed on the pump shaft through a key; Both sides of the impeller are inlaid with impeller mouth rings, and both sides of the diversion shell are inlaid with shell mouth rings. 5. The high-temperature long-axis molten salt pump for solar thermal power generation according to claim 1, characterized in that: The support and damping structure includes: pump bottom plate, storage tank flange, support pipe, flanged bellows expansion joint and foundation; The outer side of the pump bottom plate is fixed on the foundation, the bottom is provided with a storage tank flange, and the top of the storage tank flange and the inner side of the pump bottom plate are provided with flanged bellows expansion joints for shock absorption; The support pipe is connected and fixed with the vertical support pipe through the flange plate, and the support frame is arranged in the support pipe. 6. The high-temperature long-axis molten salt pump for solar thermal power generation according to claim 1, characterized in that: The pump shaft is a multi-section shaft connection method, and the multi-section pump shaft is fixedly connected by a shaft connection assembly. 7. The high-temperature long-axis molten salt pump for solar thermal power generation according to claim 1, characterized in that: The fluid sealing structure includes: a bearing bracket, a packing seal, a nitrogen gas inlet, a liquid outlet pipeline, a throat bushing, a discharge pipeline, an outlet section, a nitrogen isolation chamber and an insulation layer; A nitrogen isolation chamber is arranged in the outlet section, and the nitrogen isolation chamber isolates the pump shaft of this section from the outlet pipeline of the outlet section. A throat bushing is arranged at the bottom of the nitrogen isolation chamber, and the throat The bushing is installed on the outer wall of the pump shaft; The upper part of the nitrogen isolation chamber is connected with a nitrogen inlet, and the lower part is provided with a discharge pipeline, so that the nitrogen isolation chamber is connected with the storage tank; A packing seal is provided on the top of the outlet section, and the packing seal is filled between the pump shaft and the core hole of the flange plate, and an insulating layer is provided at the bottom of the bearing bracket. 8. The high-temperature long-axis molten salt pump for solar thermal power generation according to claim 1, characterized in that: The bearing cooling device includes: an upper fan cover, an upper fan, a bearing box, an oil hole, an oil retaining sleeve, an air induction groove, a lower fan, a lower fan cover, a bearing sleeve and a bearing; A bearing box is installed in the bearing bracket through a flange plate, a bearing and a bearing sleeve are arranged in the bearing box, the bearing is arranged on the upper part of the bearing sleeve, and an oil retaining sleeve is arranged on the outer side of the lower part of the bearing sleeve. The bearing housing is provided with an oil hole connected to the top of the bearing; An upper fan and a lower fan are respectively installed on the pump shafts on the upper and lower sides of the bearing box, and an upper fan cover and a lower fan cover are respectively installed on the outer sides of the upper fan and the lower fan. 9. The high-temperature long-axis molten salt pump for solar thermal power generation according to claim 8, characterized in that: The bearing is an angular contact ball bearing; the bearing box is processed with air-introducing grooves for increasing the cooling area. 10. The high-temperature long-axis molten salt pump for solar thermal power generation according to claim 1, characterized in that: The high-temperature molten salt area of the outlet section is wrapped with a ceramic fiber blanket, and covered with moisture-proof materials and metal sheets for binding and fixing.