A molten salt transport pipeline that reduces heat loss and can regulate the pressure at the connection point with the heat collector pipe.

Abstract

This invention discloses a molten salt conveying pipeline that reduces heat loss and regulates the pipeline pressure at the connection point with the collector tubes. The pipeline includes a straight pipe assembly, an elbow assembly, a tee assembly, a connecting valve assembly, a starting end assembly, and a ending end assembly. Each assembly includes an inner pipe and an outer pipe. The outer pipes of each assembly are fixedly connected by flanges. Installation doors are provided on the outer pipes of each assembly. A vent is fixedly connected to the inner pipe outlet and the outer pipe of the ending end assembly via a tee. By adjusting the opening of the connecting valve, the pressure at each outlet and inlet point of the pipeline working section is kept consistent, ensuring that each group of collector tubes in the collector zone operates under identical conditions, reducing differences in operating conditions between groups of collector tubes, and improving the efficiency of the collector tubes.

Description

Technical Field

[0001] This invention belongs to the field of solar thermal power generation technology, specifically relating to a molten salt transport pipeline that reduces heat loss and can regulate the pipeline pressure at the connection with the collector tube. Background Technology

[0002] Existing pipeline systems typically address pressure loss caused by excessively long pipelines by increasing the outlet pressure of the delivery pump to reach a set pressure at the pipeline end. However, the pressure is higher closer to the delivery pump. To ensure the collector tube inlet pressure remains within the set range, the pressure at the inlet of each collector tube needs to be reduced by adjusting the collector tube inlet regulating valve. Since pressure at different points within the pipeline is interconnected, adjusting the inlet pressure of one collector tube will affect the inlet pressure of others, requiring further adjustment of those pressures. This increases the difficulty of adjustment, necessitates frequent operation, and reduces the efficiency of the collector tubes. When the high-temperature molten salt exiting the outlet enters the high-temperature molten salt return pipe and returns to the high-temperature molten salt tank, the return resistance of the collector tube farthest from the high-temperature molten salt tank is much greater than that of the collector tube closest to the high-temperature molten salt tank. Even with the use of a diversion pump, it is impossible to make the return resistance at the farthest end of the high-temperature molten salt return pipe equal to the resistance at the nearest end. This results in a smaller pressure difference between the inlet and outlet of the collector tube further away, a smaller molten salt flow rate, and a lower collector tube efficiency. The pipeline system described in this invention can effectively adjust the inlet pressure of each collector tube to be the same and can effectively adjust the end resistance of the high-temperature molten salt return pipe to be the same as the near end resistance, so that each collector tube can operate efficiently and improve efficiency.

[0003] When the heat collection zone stops working, existing systems transport molten salt to the heat collection pipes via a low-temperature molten salt transport pipe, then back to the low-temperature molten salt storage tank via a high-temperature molten salt transport pipe. This allows the piping system and heat collection pipes to cool down according to a cooling curve. However, this process results in significant heat loss, greatly reducing the utilization rate of thermal energy. The piping system described in this invention allows molten salt to flow through the inner pipe, through the inner and outer pipe circulation valves at the end of the pipe, into the outer pipe, and then back to the molten salt storage tank after the heat collection zone stops working. This allows the piping system to cool down according to a cooling curve, greatly reducing heat loss and improving thermal utilization. Simultaneously, the flow rate in the inner pipe of the low-temperature molten salt pipeline is increased, and the flow rate of molten salt entering the heat collection pipe is controlled by adjusting the heat collection pipe regulating valve, allowing the heat collection pipe to cool down according to the cooling curve. Molten salt exiting the heat collection pipe enters the high-temperature return pipe, then through the outer pipe of the high-temperature return pipe, and finally through the low-temperature tank connecting valve into the low-temperature molten salt tank. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the issues of large heat loss and uneven pressure at the near and far ends of the molten salt transport pipeline in a solar thermal power generation system, and to propose a molten salt transport pipeline that reduces heat loss and can regulate the pipeline pressure at the connection with the collector tube.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A molten salt transport pipeline that reduces heat loss and regulates the pipeline pressure at the connection with the heat collector tube includes a straight pipe assembly, an elbow assembly, a tee assembly, a connecting valve assembly, a starting end assembly, and a ending end assembly. Each of the straight pipe assembly, elbow assembly, tee assembly, connecting valve assembly, starting end assembly, and ending end assembly includes an inner pipe and an outer pipe. The outer pipes of each of the straight pipe assembly, elbow assembly, tee assembly, connecting valve assembly, starting end assembly, and ending end assembly are fixedly connected by flanges. Each of the outer pipes of the straight pipe assembly, elbow assembly, tee assembly, connecting valve assembly, starting end assembly, and ending end assembly has an installation door. A vent is fixedly connected to one end of the inner pipe and one end of the outer pipe of the ending end assembly.

[0006] The inner and outer pipes of the straight pipe assembly and the elbow assembly are connected by an axial and radial bidirectional movable bracket, while the inner and outer pipes of the tee assembly and the connecting valve assembly are connected by a fixed bracket.

[0007] The inner and outer tubes of the lead-out ends of the starting and ending assemblies are connected by a fixed bracket, and the inner and outer tubes of the flange ends of the starting and ending assemblies are connected by an axial displacement bracket.

[0008] One end of the inner tube is provided with an external threaded screw, and the other end of the inner tube is provided with an internal threaded nut.

[0009] The inner and outer tubes of the starting end assembly are both connected to the regulating valve, the delivery pump, and the return pump via a tee.

[0010] The inner tube of the end assembly is connected to the vent and the circulation tube via a tee.

[0011] The connecting valve assembly includes a valve stem, one end of which is fixedly connected to an open valve core, a sealing element is provided in the middle of the valve stem, and a fixing frame is fixedly connected to the outside of the sealing element. The fixing frame is fixedly connected to the outer pipe.

[0012] Compared with the prior art, the present invention has the following beneficial effects: By controlling the opening of the connecting valve, the pressure at each outlet point 40 and inlet point 39 is adjusted, ensuring consistent pressure across the entire working section of the conveying and return pipelines. This ensures uniform operating conditions for each group of collector tubes in the heat collection zone, reducing differences in operating conditions and improving collector tube efficiency. When the heat collection zone stops operating, the low-temperature pipeline closes the regulating valve and the connecting valve assembly, opens the outer pipe return valve, and simultaneously opens the end-end assembly circulation valve. This allows the low-temperature molten salt to be transported through the inner pipe of the conveying pipe to the end, then flows through the circulation valve to the outer pipe, and finally returns to the low-temperature molten salt tank through the outer pipe return valve. Adjusting the outer pipe return valve controls the molten salt flow rate in both the inner and outer pipes, causing the pipeline to cool according to the cooling curve, and vice versa for heating. Because the molten salt circulation is essentially completed within a single pipe, eliminating the need for a separate circulation pipe, the heat dissipation area of ​​the pipeline is significantly reduced, thus decreasing heat loss and improving thermal efficiency. When the heat collection zone stops working, the high-temperature reflux pipe closes the connecting valve assembly, closes the inner and outer pipe diversion valves and diversion pump, opens the inner pipe delivery valve, and opens the end-component circulation valve. This allows the high-temperature molten salt to be transported through the inner pipe of the high-temperature reflux pipe to the end-component, then flows through the circulation valve to the outer pipe, and finally flows back to the high-temperature molten salt tank through the outer pipe reflux valve. By adjusting the outer pipe reflux valve, the flow rate of molten salt in the inner and outer pipes is controlled, causing the pipeline to cool down according to the cooling curve; the same applies to heating. Because the molten salt circulation is essentially completed within a single pipe, there is no need for a separate circulation pipe, thus greatly reducing the heat dissipation area of ​​the pipeline, reducing heat loss, and improving thermal efficiency. Simultaneously, the flow rate of molten salt in the inner pipe of the low-temperature molten salt pipeline is increased. By adjusting the heat collection pipe regulating valve, the flow rate of molten salt entering the heat collection pipe is controlled, causing the heat collection pipe to cool down according to the cooling curve. Molten salt exiting the heat collection pipe enters the high-temperature reflux pipe and passes through the outer pipe. Depending on the temperature of the refluxed molten salt, the molten salt either enters the high-temperature tank through the outer pipe and its reflux valve, or it enters the low-temperature tank through the connecting valve of the outer pipe.

[0013] The inner and outer pipes of the straight pipe assembly and the elbow assembly are connected by supports that are displaceable in both the axial and radial directions. When all components are connected to form a conveying pipeline, the maximum straight connection length should meet the following requirements: the relative displacement of the inner and outer pipes caused by the expansion and contraction difference of the inner and outer pipes due to the temperature difference should be less than the maximum allowable axial and radial displacement of the supports for the inner and outer pipes of the straight pipe assembly and the elbow assembly. Attached Figure Description

[0014] Figure 1 This is a three-dimensional schematic diagram of an embodiment of the present invention.

[0015] Figure 2 This is a schematic diagram of the straight pipe assembly structure according to an embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of the straight pipe assembly structure according to an embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram of the elbow assembly structure according to an embodiment of the present invention.

[0018] Figure 5 This is a schematic diagram of the three-way component structure according to an embodiment of the present invention.

[0019] Figure 6 This is a schematic diagram of the connecting valve assembly structure according to an embodiment of the present invention.

[0020] Figure 7 This is a schematic diagram of the starting component structure according to an embodiment of the present invention.

[0021] Figure 8 This is a schematic diagram of the end component structure in an embodiment of the present invention.

[0022] Figure 9 This is a schematic diagram of the working process of an embodiment of the present invention.

[0023] Attached Figures and Their Names: Straight Pipe Assembly 1, Elbow Assembly 2, Tee Assembly 3, Connecting Valve Assembly 4, Starting End Assembly 5, Ending End Assembly 6, Inner Pipe 7, Outer Pipe 8, Flange 9, Mounting Door 10, Vent 11, Axial and Radial Bidirectional Moving Bracket 12, Fixed Bracket 13, Axial Displacement Bracket 14, External Threaded Screw 15, Internal Threaded Nut 16, Regulating Valve 17, Circulation Pipe 18, Valve Stem 19, Open Valve Core 20, Sealing Component 21, Fixing Frame 22, Low Temperature Molten Salt Transfer Pump 23, Outer Pipe Return Valve 24, Circulation Valve 25, Collector Pipe 27, High Temperature Molten Salt Tank 28, Inner Pipe Drain Valve 29, Outer Pipe Drain Valve 30, Inner Pipe Drain Pump 31, Outer Pipe Drain Pump 32, Inner Pipe Transfer Valve 33, Low Temperature Tank Connecting Valve 35, Low Temperature Molten Salt Tank 37, Collector Pipe Regulating Valve a 38, Collector Pipe Regulating Valve Inlet Point 39, Collector Pipe Regulating Valve Outlet Point 40. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0025] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] Example 1 like Figure 1-9As shown, the molten salt conveying pipeline of the present invention, which reduces heat loss and can regulate the pipeline pressure at the connection with the heat collection pipe, includes a straight pipe assembly 1, an elbow assembly 2, a tee assembly 3, a connecting valve assembly 4, a starting end assembly 5, and a ending end assembly 6. Each of the straight pipe assembly 1, elbow assembly 2, tee assembly 3, connecting valve assembly 4, starting end assembly 5, and ending end assembly 6 includes an inner pipe 7 and an outer pipe 8. The outer pipe of each of the straight pipe assembly 1, elbow assembly 2, tee assembly 3, connecting valve assembly 4, starting end assembly 5, and ending end assembly 6... All 8 components are fixedly connected via flanges 9. Installation doors 10 are provided on the outer pipes 8 of the straight pipe assembly 1, elbow assembly 2, tee assembly 3, connecting valve assembly 4, starting end assembly 5, and ending end assembly 6. A vent 11 is fixedly connected to one end of the inner and outer pipes of the ending end assembly 6. The inner pipes 7 and outer pipes 8 of the straight pipe assembly 1 and elbow assembly 2 are connected via axial and radial bidirectional moving supports 12. The inner pipes 7 and outer pipes 8 of the tee assembly 3 and connecting valve assembly 4 are connected via fixed supports 13. The starting end... The inner tube 7 and outer tube 8 of the lead-out ends of component 5 and the end component 6 are connected by a fixed bracket 13. The inner tube 7 and outer tube 8 of the flange ends of the starting end component 5 and the end component 6 are connected by an axial displacement bracket 14. One end of the inner tube 7 is provided with an external threaded screw 15, and the other end of the inner tube 7 is provided with an internal threaded nut 16. The inner tube 7 and outer tube 8 of the starting end component 5 are both connected to a regulating valve 17, a delivery pump, and a return pump through a three-way assembly 3. The inner tube 7 of the end component 6 is connected to a vent 11 and a circulation valve through a three-way assembly. Pipe 18, the connecting valve assembly 4 includes a valve stem 19, one end of which is fixedly connected to an open valve core 20, and a sealing element 21 is provided in the middle of the valve stem 19. A fixing frame 22 is fixedly connected to the outside of the sealing element 21, and the fixing frame 22 is fixedly connected to the outer pipe 8. The cryogenic molten salt conveying pump 23 is turned on, the regulating valve 17 of the inner pipe 7 and the outer pipe 8 of the conveying pipeline is turned on, and the outer pipe return valve 24 is turned off. The cryogenic molten salt enters the conveying pipeline and at the same time the circulation valve 25 of the end assembly 6 is turned off. The vent 11 automatically opens due to the pressure increase and discharges nitrogen. The cryogenic molten salt fills the pipeline. The regulating valve 17 is adjusted so that the pressure in the inner pipe 7 is greater than that in the outer pipe 8. The connecting valve assemblies 4 are adjusted to compensate for the pressure in the outer pipe 8 so that the inlet pressure of each heat collection tube 27 is the same. Open the high-temperature molten salt tank 28, the inner tube diversion valve 29 and the outer tube diversion valve 30, and start the inner tube diversion pump 31 and the outer tube diversion pump 32. Close the inner tube delivery valve 33, the outer tube return valve 24 and the low-temperature tank connecting valve 35. Adjust the inner tube diversion valve 29 and the outer tube diversion valve 30 to make the pressure in the inner tube 7 less than the pressure in the outer tube 8. Adjust each connecting valve assembly 4 to make the outlet pressure of each heat collector tube 27 the same, so that each heat collector tube 27 operates under the same conditions, thereby improving the heat collection efficiency. Increase the inlet pressure of the heat collector tube 27 to be less than the maximum working pressure of the heat collector tube 27, and decrease the outlet pressure of the heat collector tube 27 to increase the pressure difference of the heat collector tube 27, so that each heat collector tube 27 operates at its maximum rated power, thereby improving the heat collection efficiency.By adjusting the opening of the connecting valve assembly 4, the inlet and outlet pressures of the collector tube 27 are stabilized, reducing the adjustment frequency of the collector tube regulating valve a38, thus ensuring stable operation of the heat collection system and improving heat collection efficiency. When the heat collection zone stops working, the low-temperature pipeline closes the regulating valve 17, closes the connecting valve assembly 4, opens the outer pipe return valve 24, and simultaneously opens the end-end assembly circulation valve 25. This allows the low-temperature molten salt to be transported through the inner pipe of the delivery pipe to the end-end assembly 6, then flows through the circulation valve 25 to the outer pipe, and finally flows back to the low-temperature molten salt tank 37 through the outer pipe return valve 24. By adjusting the outer pipe return valve 24, the flow rate of molten salt in the inner and outer pipes is controlled, causing the pipeline to cool down according to the cooling curve, and vice versa for heating. Because the molten salt circulation is essentially completed within a single pipe, there is no need for a separate circulation pipeline, thus greatly reducing the heat dissipation area of ​​the pipeline, reducing heat loss, and improving thermal efficiency. When the heat collection zone stops working, the high-temperature pipeline closes the connecting valve assembly 4, closes the inner pipe drainage valve 29, outer pipe drainage valve 30, inner pipe drainage pump 31, and outer pipe drainage pump 32, opens the inner pipe delivery valve 33, and opens the end-end assembly circulation valve 25. This allows the high-temperature molten salt to be transported through the high-temperature return pipe inner pipe to the end end, then through the circulation valve 25 to the outer pipe 8, and finally back to the high-temperature molten salt tank 28 through the outer pipe return valve 24. By adjusting the outer pipe return valve 24, the flow rate of molten salt in the inner pipe 7 and outer pipe 8 is controlled, causing the pipeline to cool down according to the cooling curve; the same applies to heating. Because the molten salt circulation is essentially completed within a single pipe, there is no need for a separate circulation pipeline, thus greatly reducing the heat dissipation area of ​​the pipeline, reducing heat loss, and improving thermal efficiency. At the same time, the flow rate in the low-temperature molten salt pipeline inner pipe 7 is increased, and the flow rate of molten salt entering the heat collection pipe is controlled by adjusting the heat collection pipe regulating valve a38, causing the heat collection pipe to cool down according to the cooling curve. Molten salt exiting from collector tube 27 enters the high-temperature reflux pipe and then the outer pipe of the high-temperature reflux pipe. Depending on the temperature of the refluxed molten salt, the molten salt enters the high-temperature molten salt tank 28 via the outer pipe of the high-temperature reflux pipe and the reflux valve 24, or enters the low-temperature molten salt tank 37 via the outer pipe of the high-temperature reflux pipe and the connecting valve 35 of the low-temperature tank.

[0027] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used in this article to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for the purpose of helping to understand the principles of the embodiments of the present invention.

Claims

1. A molten salt conveying pipeline that reduces heat loss and regulates the pipeline pressure at the connection with the heat collector pipe, comprising a straight pipe assembly (1), an elbow assembly (2), a tee assembly (3), a connecting valve assembly (4), a starting end assembly (5), and a ending end assembly (6), characterized in that: The straight pipe assembly (1), elbow assembly (2), tee assembly (3), connecting valve assembly (4), starting end assembly (5) and ending end assembly (6) all include an inner pipe (7) and an outer pipe (8). The starting end assembly (5) and the ending end assembly (6) are sequentially arranged with a connecting valve assembly (4), a straight pipe assembly (1), a connecting valve assembly (4), a straight pipe assembly (1), a connecting valve assembly (4), an elbow assembly (2), a straight pipe assembly (1), an elbow assembly (2), a connecting valve assembly (4), a straight pipe assembly (1), a connecting valve assembly (4), a straight pipe assembly (1), and a connecting valve assembly (4). The outer pipes (8) of adjacent pipe fittings are all fixedly connected by flanges (9). The outer pipes (8) of the straight pipe assembly (1), elbow assembly (2), tee assembly (3), connecting valve assembly (4), starting end assembly (5) and ending end assembly (6) are all provided with installation doors (10), and the inner and outer pipes of the ending end assembly (6) are respectively fixedly connected with vents (11). The inner tube (7) and outer tube (8) of the starting end component (5) are connected to the regulating valve (17), the delivery pump and the return pump through a tee (42). The molten salt delivery pipeline is provided with multiple heat collection tubes in parallel, and the multiple heat collection tubes are respectively connected to the outer tube (8) of each connecting valve component. The inner tube (7) of the end assembly (6) is connected to the vent (11) and the circulation tube (18) via a tee. A circulation valve (25) is provided on the circulation pipe (18); The connecting valve assembly (4) includes a valve stem (19), one end of which is fixedly connected to an open valve core (20). The valve core controls the flow of molten salt between the inner tube and the outer tube. A sealing element (21) is provided in the middle of the valve stem (19), and a fixing frame (22) is fixedly connected to the outside of the sealing element (21). The fixing frame (22) is fixedly connected to the outer tube (8).

2. The molten salt conveying pipeline according to claim 1, which reduces heat loss and can regulate the pipeline pressure at the connection with the heat collection pipe, is characterized in that: The inner pipe (7) and outer pipe (8) of the straight pipe assembly (1) and the elbow assembly (2) are connected by an axial and radial bidirectional moving bracket (12), and the inner pipe (7) and outer pipe (8) of the tee assembly (3) and the connecting valve assembly (4) are connected by a fixed bracket (13).

3. The molten salt conveying pipeline according to claim 1, which reduces heat loss and can regulate the pipeline pressure at the connection with the heat collector pipe, is characterized in that: The inner tube (7) and outer tube (8) of the lead-out ends of the starting end assembly (5) and the ending end assembly (6) are connected by a fixed bracket (13), and the inner tube (7) and outer tube (8) of the flange ends of the starting end assembly (5) and the ending end assembly (6) are connected by an axial displacement bracket (14).

4. The molten salt conveying pipeline according to claim 1, which reduces heat loss and can regulate the pipeline pressure at the connection with the heat collector pipe, is characterized in that: One end of the inner tube (7) is provided with an external threaded screw (15), and the other end of the inner tube (7) is provided with an internal threaded nut (16).

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