Tower type molten salt tubular heat absorber system for solar thermal power generation

Abstract

The present application relates to the technical field of tower type photo-thermal power generation, and particularly relates to a molten salt tubular heat absorber system for tower type photo-thermal power generation. In the present application, the inlet buffer tank is in one-to-one communication with multiple groups of tube panel assemblies through multiple tube panel inlet pipes connected to the inlet buffer tank. A tube panel molten salt flow regulating valve is arranged on each tube panel inlet pipe near the inlet buffer tank. One end of each tube panel outlet pipe is connected to the corresponding tube panel assembly, and the other end is connected to one end of an adjacent tube panel communication pipe through a corresponding three-way valve. The other end of the tube panel communication pipe is in communication with any other group of tube panel inlet pipes. The tube panel outlet pipe corresponding to the tube panel assembly at the beginning or end is directly connected to the corresponding downcomer, and the tube panel outlet pipe corresponding to the other tube panel assemblies is connected to the corresponding downcomer through a corresponding three-way valve. The present application can ensure efficient parallel operation under high light intensity, and can maintain the necessary molten salt flow rate by switching to a series mode under low light intensity, effectively avoiding molten salt solidification and improving the reliability of system operation.

Description

Technical Field

[0001] This invention relates to the field of tower-type concentrated solar power (CSP) technology, and more particularly to a molten salt tube receiver system for tower-type CSP. Background Technology

[0002] In current tower-type concentrated solar power (CSP) technology, the molten salt tube receiver system, as a core component, bears the crucial responsibility of efficiently converting solar radiation into heat energy. However, some inherent problems in traditional designs limit the overall performance and operational efficiency of the system. Systems employing two sets of tubes operating in parallel exhibit significant limitations under low light or low load conditions. Since each tube set consists of several fine absorber tubes, to prevent the molten salt from solidifying and clogging the tubes at low temperatures, the flow rate of the molten salt within the tube set must be maintained between 1 and 4 m / s, with an optimal range of 2 to 4 m / s. This means the receiver must operate within a load range of at least 30% to 110% to ensure normal operation. Once external sunlight weakens and the system load rate drops below 30%, traditional practices face a dilemma: either shut down the system, resulting in wasted solar energy, or continue operating the receiver at the normal flow rate, which would lead to insufficient heat input and excessively low molten salt outlet temperatures. This process not only failed to make effective use of solar energy, but also resulted in the system consuming more energy than it gained due to the operation of the high-energy-consuming molten salt pump, thus greatly reducing its economic efficiency. Summary of the Invention

[0003] (a) Technical problems to be solved In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a molten salt tube receiver system for tower solar thermal power generation, which solves the technical problem of solidification risk caused by slow molten salt flow under low light conditions in tower solar thermal power generation systems.

[0004] (II) Technical Solution To achieve the above objectives, the main technical solutions adopted by the present invention include: A molten salt tube receiver system for tower-type concentrated solar power generation includes an inlet buffer tank, multiple sets of tube screen assemblies, three-way valves, downcomers, tube screen outlet pipes, tube screen inlet pipes, and tube screen connecting pipes. The inlet buffer tank is connected to multiple sets of tube screen assemblies one by one through multiple tube screen inlet pipes connected to it. Each tube screen inlet pipe is equipped with a tube screen regulating valve near the inlet buffer tank. One end of each tube screen outlet pipe is connected to the corresponding tube screen assembly, and the other end is connected to one end of the adjacent tube screen connecting pipe or to the corresponding downcomer through a corresponding three-way valve. The other end of the tube screen connecting pipe is connected to any other set of tube screen inlet pipes. The tube screen outlet pipe corresponding to the beginning or end of the tube screen assembly is directly connected to the corresponding downcomer, and the tube screen outlet pipes corresponding to the other tube screen assemblies are connected to the corresponding downcomer through corresponding three-way valves.

[0005] This tower-type solar thermal power generation molten salt tube receiver system, through its unique receiver structure design, especially the layout of the tube panel assembly, three-way valve, and tube panel connecting pipe, achieves flexible adjustment of the molten salt flow path during heat absorption. It can ensure high-efficiency parallel operation under high light conditions, and can maintain the necessary molten salt flow rate by switching to series mode under low light conditions, effectively avoiding molten salt solidification and significantly improving the system's adaptability and operational stability under a wide range of light conditions.

[0006] Optionally, adjacent downcomers are connected by multiple downcomer connecting pipes, and each downcomer connecting pipe is equipped with a downcomer on / off valve.

[0007] By adding downcomer connecting pipes and on / off valves between downcomers, the flexibility of molten salt flow within the system is enhanced, and it is ensured that even if one downcomer becomes blocked, molten salt can still be continuously delivered through other connecting paths, further improving the reliability and redundancy of the system.

[0008] Optionally, the imported buffer tank can be horizontal.

[0009] The use of a horizontal imported buffer tank effectively reduces the static pressure difference caused by height differences, ensures the balance of inlet flow of each tube panel component, reduces structural complexity, saves space, and improves the overall system stability.

[0010] Optionally, the receiver system also includes a bypass pipe and a riser pipe. The riser pipe is located below and connected to the inlet buffer tank. One end of the bypass pipe is connected to the riser pipe, and the other end of the bypass pipe is connected to multiple downcomers.

[0011] The integrated bypass pipe and riser pipe, combined with the downcomer pipe, form a closed loop, which not only facilitates preheating during system startup and heat recovery during daily operation, but also provides an additional flow path for the molten salt, enhancing the flexibility and efficiency of system operation.

[0012] Optionally, the receiver system includes an upper connecting pipe and a lower connecting pipe. Each tube panel assembly includes multiple tube panels. Each group of adjacent tube panels is connected by an upper connecting pipe or a lower connecting pipe. The upper connecting pipe is located at the upper end of the tube panel assembly, and the lower connecting pipe is located at the lower end of the tube panel. The upper connecting pipe and the lower connecting pipe are staggered and connected to adjacent tube panels.

[0013] The introduction of upper and lower connecting pipes optimizes the molten salt circulation inside the tube panel assembly. The staggered connection design promotes uniform heat transfer, improves heat utilization efficiency, and facilitates system maintenance.

[0014] Optionally, the system also includes an exhaust branch pipe, an exhaust main pipe, an exhaust valve, and an exhaust tank. One end of the exhaust branch pipe is connected to the upper manifold connection pipe, and the other end of the exhaust branch pipe is connected to the exhaust main pipe. The end of the exhaust main pipe is connected to the pipe screen outlet pipe or downcomer pipe after passing through the exhaust tank.

[0015] The exhaust system, including exhaust branch pipes, main pipes, valves, and tanks, effectively removes non-condensable gases from the system, reduces gas resistance in the pipeline, ensures smooth flow of molten salt, and also avoids localized overheating caused by bubbles, thus improving the safety of system operation.

[0016] The venting tank receives gas from the system, allowing it to be expelled in a timely manner and making the system more stable. Furthermore, during the venting process, a small amount of molten salt flows out along with the gas; this molten salt is recovered by connecting the venting tank to the outlet pipe or downcomer of the pipe panel.

[0017] Optionally, the system also includes a salt-draining branch pipe, a salt-draining valve, and a salt-draining main pipe. One end of the salt-draining branch pipe is connected to the pipe screen assembly via a lower connecting pipe or the pipe screen inlet pipe, and the other end of the salt-draining branch pipe is connected to the salt-draining main pipe. One end of the salt-draining main pipe is connected to the pipe screen inlet pipe, and the end of the salt-draining main pipe is connected to the pipe screen outlet pipe or downcomer on the corresponding pipe screen assembly.

[0018] The configuration of the salt-draining branch pipe, salt-draining valve, and salt-draining main pipe enables rapid replacement of molten salt and system cleaning. Especially during system shutdown maintenance, it can effectively prevent molten salt from solidifying at low temperatures, ensuring long-term stable operation of the system and convenient maintenance.

[0019] Optionally, the end of the inlet pipe of the tube screen is divided into two branches, namely the first inlet pipe and the second inlet pipe. The first inlet pipe is equipped with a first inlet regulating valve and the second inlet pipe is equipped with a second inlet regulating valve. The first inlet pipe is connected to the tube screen at the beginning of each group, and the second inlet pipe is connected to the salt evaporation main pipe.

[0020] By dividing the inlet pipe of the tube panel into a first inlet pipe and a second inlet pipe, and equipping each with a regulating valve, more precise flow control is achieved. Especially during system startup and low-load operation, the molten salt flow can be managed more flexibly, improving the system's response speed and energy efficiency.

[0021] Optionally, the system also includes a high-temperature molten salt tank, a molten salt heat exchanger, a low-temperature molten salt tank, a high-temperature molten salt tank regulating valve, and a low-temperature molten salt tank regulating valve. Each downcomer is connected to the high-temperature molten salt tank or the low-temperature molten salt tank via the high-temperature molten salt tank regulating valve or the low-temperature molten salt tank regulating valve, respectively. The high-temperature molten salt tank is connected to the low-temperature molten salt tank via the molten salt heat exchanger, and the low-temperature molten salt tank is connected to the inlet buffer tank via the riser pipe.

[0022] The integration of high-temperature molten salt tanks, molten salt heat exchangers, and low-temperature molten salt tanks, along with the corresponding regulating valve configuration, constructs an efficient heat storage and conversion mechanism. This not only ensures the effective utilization and storage of thermal energy but also optimizes the overall thermodynamic cycle of the system and improves solar energy conversion efficiency.

[0023] Optionally, a molten salt flow meter may be installed on the outlet pipe of the tube screen.

[0024] Installing a molten salt flow meter on the outlet pipe of the tube panel provides real-time and accurate flow monitoring data for the system, which helps operators to precisely control and adjust the system, further improving the system's automation level and operational economy. Especially during the system's salt filling phase, the molten salt flow rate can be used to determine whether the tube panel is fully filled with molten salt.

[0025] (III) Beneficial Effects The beneficial effects of this invention are as follows: The invention starts operation from the inlet buffer tank, and molten salt enters the system through multiple tube screen inlet pipes located above the inlet buffer tank. Each inlet pipe is equipped with a tube screen regulating valve, which allows for independent adjustment of the molten salt flow into each tube screen assembly, achieving independent flow control.

[0026] Molten salt flows inside the tube-panel assembly, absorbing solar heat. Each tube-panel assembly discharges the hot molten salt through its outlet pipe. Here, the three-way valve plays a crucial role. The three-way valve can control the parallel or series connection of the tube-panel assemblies according to system requirements. When the molten salt flow rate is maintained between 1 and 4 m / s, and the temperature reaches the required heating level after passing through the tube-panel assembly, the hot molten salt is directly sent to the downcomer for energy recovery or storage, and the tube-panel assemblies remain connected in parallel. When the molten salt flow rate is maintained between 1 and 4 m / s, but the temperature does not reach the required heating level after passing through the tube-panel assembly, the three-way valve reverses its direction, keeping one set of tube-panel regulating valves open, while the outlet pipes of the remaining tube-panel assemblies are connected to the adjacent outlet pipes, thus forming a series connection between multiple tube-panel assemblies and increasing the flow path of the molten salt. This not only prevents the molten salt from solidifying but also absorbs more sunlight, ensuring the temperature of the molten salt in the downcomer, improving the system's adaptability and efficiency under low light conditions, and enhancing the reliability of system operation.

[0027] With this layout, the system can not only make full use of the high throughput of the parallel mode under high load, but also maintain the stability of the system operation under low load through flexible traffic redistribution and operation mode switching (such as parallel to series), while reducing unnecessary energy consumption and ensuring overall economy and energy efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall process of the molten salt tube receiver system for tower-type solar thermal power generation according to the present invention; Figure 2 for Figure 1 Schematic diagram of the process flow of the high-temperature molten salt tank and the low-temperature molten salt tank in the process; Figure 3 for Figure 1 Schematic diagram of the connection structure between the imported buffer tank and the tube shield assembly; Figure 4 for Figure 1 Schematic diagram of the central tube screen assembly.

[0029] [Explanation of Labels in the Attached Image] 1. Inlet buffer tank; 2. Tube screen assembly; 3. Three-way valve; 4. Downcomer; 5. Tube screen outlet pipe; 6. Connecting pipe; 7. Tube screen inlet pipe; 8. Tube screen regulating valve; 9. Downcomer connecting pipe; 10. Downcomer on / off valve; 11. Bypass pipe; 12. Ascend pipe; 13. Exhaust branch pipe; 14. Exhaust main pipe; 15. Exhaust valve; 16. Exhaust tank; 17. Upper manifold connecting pipe; 18. Lower manifold connecting pipe; 19. Salt drain branch pipe; 20. Salt drain valve; 21. Salt drain main pipe; 22. First inlet pipe; 23. Second inlet pipe; 24. First inlet regulating valve; 25. Second inlet regulating valve; 26. High-temperature molten salt tank; 27. Molten salt heat exchanger; 28. Low-temperature molten salt tank; 29. ​​High-temperature molten salt tank regulating valve; 30. Low-temperature molten salt tank regulating valve. Detailed Implementation

[0030] To better explain and facilitate understanding of the present invention, a detailed description of the invention is provided below with reference to the accompanying drawings and specific embodiments. In this document, directional terms such as "upper," "lower," etc., are used interchangeably with other directional terms. Figure 1 The orientation is used as a reference.

[0031] A tower-type solar thermal power generation system consists of five stages: light concentration, heat absorption, energy storage, heat release, and power generation. Among them, the heat absorption system is the key to realizing the conversion of light energy into heat energy. The efficiency, stability, and reliability of the heat absorption system determine the overall performance of the entire system. This application is a related improvement to the heat absorption system.

[0032] In existing technologies, the purpose of setting up an outlet buffer tank is to provide a buffer space for the molten salt within the tube panel assembly 2 when system blockage occurs, allowing time for the evacuation of the mirror field and the shutdown of the cold molten salt pump (located in the cryogenic molten salt tank 28). Furthermore, the flow rate of the molten salt within the tube panel assembly 2 can be controlled by adjusting the liquid level in the outlet buffer tank. However, the existence of the outlet buffer tank brings problems such as system complexity, large space occupation, and high investment. This is because the volume of the outlet buffer tank must meet a molten salt flow rate of at least 60 seconds; the larger the system capacity, the larger the volume of the outlet buffer tank. Additionally, to prevent molten salt solidification and reduce heat loss, electric auxiliary heating, insulation layers, and protective layers are also required.

[0033] Through precisely designed components and control strategies, this system achieves efficient capture and utilization of solar radiation energy. Even when the light intensity fluctuates significantly, it can ensure stable operation of the system, thus significantly improving the solar energy conversion efficiency and system economy.

[0034] The core of the system includes an inlet buffer tank 1, multiple sets of tube panel assemblies 2, a three-way valve 3, and a downcomer 4. It innovatively utilizes the clever arrangement of the tube panel connecting pipe 6 and the three-way valve 3 to achieve flexible switching between parallel and series connection of the heat-absorbing tube panel assemblies 2. When there is sufficient sunlight, the system operates in parallel mode to ensure high efficiency; when sunlight is insufficient, it switches to series mode to extend the molten salt flow path, maintaining the necessary flow velocity (e.g., 2.1 m / s) even at low flow rates, effectively preventing molten salt solidification and avoiding the risk of pipe blockage.

[0035] The system also integrates exhaust, salt-draining, and molten salt flow monitoring mechanisms to ensure smooth molten salt flow and precise temperature control, further enhancing the overall reliability and adaptability of the system. For example, the exhaust branch pipe 13 and exhaust main pipe 14 help to remove accumulated gas and excess molten salt from the system, while the salt-draining branch pipe 19 and salt-draining main pipe 21 facilitate rapid preheating of the molten salt during system startup and molten salt recovery during shutdown, preventing solidification.

[0036] The solar radiation sensor on the tube panel assembly 2 can monitor the light intensity in real time, intelligently adjust the molten salt flow rate, ensure that the outlet temperature remains stable at the design value (e.g., 565℃), and automatically optimize the operating mode in response to changes in light intensity. This series of designs optimizes the system's performance within the operating temperature range of 290℃ to 565℃, expands the load regulation range to 15%-110%, and provides strong technical support for the efficient and continuous operation of the solar thermal power generation system.

[0037] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0038] Example 1: Reference Figure 1 and Figure 2A molten salt tube receiver system for tower-type concentrated solar power generation includes an inlet buffer tank 1, multiple sets of tube screen assemblies 2, a three-way valve 3, a downcomer 4, a tube screen outlet pipe 5, a tube screen inlet pipe 7, and a tube screen connecting pipe 6. The inlet buffer tank 1 is connected to multiple sets of tube screen assemblies 2 one by one through multiple tube screen inlet pipes 7 (located above or to the side of it). Each tube screen inlet pipe 7 is equipped with a tube screen regulating valve 8 near the inlet buffer tank 1. One end of each tube screen outlet pipe 5 is connected to the corresponding tube screen assembly 2, and the other end is connected to one end of the adjacent tube screen connecting pipe 6 through the corresponding three-way valve 3. The other end of the tube screen connecting pipe 6 is connected to any other set of tube screen inlet pipes 7 or to the corresponding downcomer 4 through the corresponding three-way valve 3. The tube screen outlet pipe 5 corresponding to the beginning or end of the tube screen assembly 2 is directly connected to the corresponding downcomer 4, and the tube screen outlet pipe 5 corresponding to the other tube screen assemblies 2 is connected to the corresponding downcomer 4 through the corresponding three-way valve 3. The "starting end" refers to the tube panel 2 closest to it, and the "ending end" refers to the tube panel 2 furthest from it. The tube panel outlet pipe 5 of the starting tube panel 2 is directly connected to the downcomer pipe 4, while the outlet pipes 5 of the remaining tube panel 2 are connected to the downcomer pipe 4 via a three-way valve 3, thus ensuring that all tube panel 2 components can be connected in series. Alternatively, the tube panel outlet pipe 5 of the ending tube panel 2 is directly connected to the downcomer pipe 4, while the outlet pipes 5 of the remaining tube panel 2 are connected to the downcomer pipe 4 via a three-way valve 3, thus ensuring that all tube panel 2 components can be connected in series. Or, it can be interpreted that one set of tube panel 2 components corresponding to the starting and ending ends is directly connected to the downcomer pipe 4, and the other set is connected to the downcomer pipe 4 at one end via a three-way valve 3, and at the other end via a tube panel connecting pipe 6 to an adjacent tube panel 2 component. The tube panel 2 components between the starting and ending ends, and adjacent tube panel 2 components, can be connected through the tube panel outlet pipe 5, the three-way valve 3, and the tube panel connecting pipe 6 to form a series connection mode between the tube panel 2 components.

[0039] In this embodiment, two sets of tube screen components 2 are preferred.

[0040] The regulating valve 8 controls the opening and closing of molten salt entering the tube panel assembly 2 and adjusts the flow rate, ensuring the most crucial flow of molten salt. When multiple tube panel assemblies 2 are connected in parallel, the regulating valve 8 is always open to maintain the parallel connection of the tube panel assemblies 2. Molten salt flows from the inlet buffer tank 1 to the upper and lower tube panel assemblies 2, and then flows to the corresponding downcomer pipes 4 (the three-way valve 3 is connected to the downcomer pipe 4), and finally to the high-temperature molten salt tank 26.

[0041] In series mode, ensure that the regulating valve 8 of one set of pipe screens is open, while the regulating valve 8 of the other set is closed. For example... Figure 1The left-hand tube screen regulating valve 8 is open, and the right-hand tube screen regulating valve 8 is closed. Molten salt flows through the left-hand tube screen inlet pipe 7 to the upper tube screen assembly 2. When it flows from the upper tube screen outlet pipe 5 to the three-way valve 3, the three-way valve 3 is connected to the connecting pipe 6. It then flows through the connecting pipe 6 to the lower tube screen assembly 2, and then through the lower tube screen outlet pipe 5 to the downcomer 4, thereby ensuring the temperature of the molten salt coming out of the downcomer 4.

[0042] To prevent molten salt from entering the connecting pipe 6 of the tube screen during parallel operation, a check valve is installed on the connecting pipe 6 of the tube screen.

[0043] Reference Figure 1 and Figure 2 Adjacent downpipes 4 are connected by multiple downpipes 9, and each downpipe 9 is equipped with a downpipe on / off valve 10.

[0044] The downcomer shut-off valve 10 ensures connectivity between adjacent downcomers 4, preventing blockage in one branch of downcomer 4 and allowing for rapid utilization of the other branch's downcomer 4, thus ensuring system continuity at all times. Downcomers 4 are typically 100-200 meters long, providing sufficient buffer space to replace the outlet buffer tank and saving tower area. The downcomer connecting pipe 9 effectively prevents blockage in downcomers 4.

[0045] By introducing connecting pipes (such as the pipe screen connecting pipe 6 and the downcomer connecting pipe 9 in the above invention), and flexibly switching between them via the three-way valve 3 or other control valves, the series or parallel operation modes of the pipe screen components 2 can be realized. This allows for flow and pressure regulation without using the outlet buffer tank, ensuring system stability. Simultaneously, it ensures that the downcomer 4 does not become blocked, and the molten salt flow is unimpeded, fundamentally replacing the buffering function of the outlet buffer tank.

[0046] The pipe screen regulating valve 8, the downcomer on / off valve 10, the first inlet regulating valve 24, the second inlet regulating valve 25, the salt drain valve 20, the high-temperature molten salt tank regulating valve 29, and the low-temperature molten salt tank regulating valve 30 can all control the on / off of molten salt and the regulation of its flow rate.

[0047] Reference Figure 1 and Figure 3 The imported buffer tank 1 is horizontal.

[0048] The imported buffer tank 1 is horizontal, which reduces the impact of static pressure difference on the pressure of the inlet pipe 7 of the pipe panel, thereby maintaining the flow balance of each branch without the aid of a regulating valve.

[0049] Two inlet pipes 7 serve as outlet branches of the inlet buffer tank 1, connecting to the first set of pipe screen assemblies 2I and the second set of pipe screen assemblies 2II, respectively. The outlet of each set of pipe screen assemblies 2I is connected to the outlet pipe 5 of the pipe screen and to the downcomer 4 of the corresponding branch. In parallel operation, the molten salt flow of the two sets of pipe screens is independent and does not interfere with each other. Adjusting the flow rate of one branch has minimal impact on the other branch, thereby improving the stability of the system operation.

[0050] The imported buffer tank 1 is horizontal and two relatively independent branches are directly led out from the imported buffer tank 1, which reduces the impact of static pressure caused by liquid level on the branch pressure and ensures the flow balance of each branch to the greatest extent. The branches are independent of each other, which effectively reduces the impact of adjustment of one branch on the other branch, thereby improving the system stability. Compared to traditional systems, the molten salt flow paths of each group of tube panel components 2 are independent from the outlet of the inlet buffer tank 1, and the downcomer pipes 4 are also independent but connected, serving as backups for each other, ensuring smooth system operation. It has the function of an outlet buffer tank without the need to install one, thus simplifying the entire system, reducing space occupation, lowering the load on the steel structure, and reducing system costs.

[0051] Reference Figure 1 and Figure 3 The receiver system also includes a bypass pipe 11 and a riser pipe 12. The riser pipe 12 is located below the inlet buffer tank 1 and is connected to the inlet buffer tank 1. One end of the bypass pipe 11 is connected to the riser pipe 12, and the other end of the bypass pipe 11 is connected to multiple downcomers 4.

[0052] A shut-off valve (located on the left side of the bypass pipe 11) is installed on the bypass pipe 11 to control the opening and closing of the bypass pipe 11. To prevent molten salt in the downcomer pipe 4 of each branch from entering the bypass pipe 11 during normal operation, a check valve (located on the right side of the bypass pipe 11) is installed on the bypass pipe 11.

[0053] The function of the bypass pipe 11 is to turn on the low-temperature molten salt pump in the low-temperature molten salt tank 28 when the system just starts to add salt, so that the molten salt flows from the low-temperature molten salt tank 28 through the bypass pipe 11 to the downcomer 4, then flows to the high-temperature molten salt tank 26, and finally flows back to the low-temperature molten salt tank 28. After the molten salt reaches the design flow rate, the salt discharge valve is opened to add salt to the pipe screen, ensuring that the molten salt circulation system can start smoothly.

[0054] Reference Figure 1 , Figure 3 and Figure 4The absorber system includes an upper connecting pipe 17 and a lower connecting pipe 18. Each tube panel assembly 2 includes multiple tube panels. Each group of adjacent tube panels is connected through the upper connecting pipe 17 or the lower connecting pipe 18. The upper connecting pipe 17 is located at the upper end of the tube panel assembly 2, and the lower connecting pipe 18 is located at the lower end of the tube panel. The upper connecting pipe 17 and the lower connecting pipe 18 are staggered and connected to the adjacent tube panels.

[0055] The series connection between individual tube panels within each tube panel group is accomplished through the cooperation of the upper manifold connecting pipe and the lower manifold connecting pipe 18.

[0056] Reference Figure 1 , Figure 3 and Figure 4 The system also includes an exhaust branch pipe 13, an exhaust main pipe 14, an exhaust valve 15, and an exhaust tank 16. One end of the exhaust branch pipe 13 is connected to the upper connecting pipe 17, and the other end of the exhaust branch pipe 13 is connected to the exhaust main pipe 14. The end of the exhaust main pipe 14 is connected to the pipe screen outlet pipe 5 or the downcomer pipe 4 after passing through the exhaust tank 16.

[0057] To prevent molten salt in the outlet pipe 5 or downcomer 4 from entering the exhaust tank 16, a check valve is installed on the connecting pipe between the exhaust tank and the outlet pipe 5.

[0058] Reference Figure 1 , Figure 3 and Figure 4 The system also includes a salt-draining branch pipe 19, a salt-draining valve 20, and a salt-draining main pipe 21. One end of the salt-draining branch pipe 19 is connected to the pipe screen assembly 2 via a lower connecting pipe 18 or a pipe screen inlet pipe 7. The other end of the salt-draining branch pipe 19 is connected to the salt-draining main pipe 21. One end of the salt-draining main pipe 21 is connected to the pipe screen inlet pipe 7. The end of the salt-draining main pipe 21 is connected to the pipe screen outlet pipe 5 or downcomer pipe 4 on the corresponding pipe screen assembly 2.

[0059] To prevent molten salt in the outlet pipe 5 of the tube screen from entering the salt evacuation main pipe 21 during normal operation, a check valve is installed on the salt evacuation main pipe 21 (located on the salt evacuation main pipe 21 near the outlet pipe 5 of the tube screen).

[0060] The system prepares for salting at sunrise each day. The first inlet regulating valve 24 is closed, and the check valve on the main salt-draining pipe 21 is shut off. The second inlet regulating valve 25 is opened, and all salt-draining valves 20 are opened. Molten salt from the inlet buffer tank 1 enters the pipe screen assembly 2 through the second inlet pipe 23, the main salt-draining pipe 21, and the lower manifold connecting pipe 18. Multiple branch salt-draining pipes 19 allow for rapid entry into the pipe screen assembly 2, and the molten salt enters from the bottom, reducing gas ingress and alleviating the burden on subsequent exhaust.

[0061] Once the salting is complete, the second inlet pipe 23 is switched to the first inlet pipe 22, the second inlet regulating valve 25 and the salt-removing valve 20 are closed, and the first inlet regulating valve 24 is opened. Molten salt enters the tube panel assembly 2 through the first inlet pipe 22 to maintain the stability of the system.

[0062] The system performs salt drainage every day at sunset to prevent molten salt from solidifying. During the salt drainage process, the molten salt in the pipe panel assembly 2 flows to the downcomer 4 through the cooperation of the salt drainage branch pipe 19, the salt drainage valve 20 and the salt drainage main pipe 21, and finally flows to the high-temperature molten salt tank 26 and the low-temperature molten salt tank 28 to prepare for salting the next day.

[0063] Reference Figure 1 and Figure 4 The end of the inlet pipe 7 of the tube screen is divided into two branches, namely the first inlet pipe 22 and the second inlet pipe 23. The first inlet pipe 22 is equipped with a first inlet regulating valve 24 and the second inlet pipe 23 is equipped with a second inlet regulating valve 25. The first inlet pipe 22 is connected to the tube screen at the beginning of each group, and the second inlet pipe 23 is connected to the salt evaporation main pipe 21.

[0064] Reference Figure 1 and Figure 2 The system also includes a high-temperature molten salt tank 26, a molten salt heat exchanger 27, a low-temperature molten salt tank 28, a regulating valve for the high-temperature molten salt tank 26, and a regulating valve for the low-temperature molten salt tank 30. Each downcomer 4 is connected to the high-temperature molten salt tank 26 or the low-temperature molten salt tank 28 via the regulating valve for the high-temperature molten salt tank 26 or the regulating valve for the low-temperature molten salt tank 30, respectively. The high-temperature molten salt tank 26 is connected to the low-temperature molten salt tank 28 via the molten salt heat exchanger 27, and the low-temperature molten salt tank 28 is connected to the inlet buffer tank 1 via the riser 12.

[0065] When the molten salt temperature reaches the temperature required for heating and discharge, the low-temperature molten salt tank regulating valve 30 is closed, allowing the molten salt from the downcomer 4 to enter the high-temperature molten salt tank 26 through the high-temperature molten salt tank 26 regulating valve. When the molten salt temperature does not reach the temperature required for heating and discharge, the high-temperature molten salt tank 26 regulating valve is closed, allowing the molten salt from the downcomer 4 to enter the low-temperature molten salt tank 28 through the low-temperature molten salt regulating valve for storage and subsequent circulation.

[0066] Reference Figure 1 To effectively monitor the molten salt flow rate within the tube panel assembly 2, a molten salt flow meter is installed on the tube panel outlet pipe 5. The molten salt flow rate parameters are transmitted to the control room via DCS, and the molten salt flow rate parameters are displayed in real time on the industrial control computer, thereby controlling the molten salt flow rate within the tube panel assembly 2.

[0067] This application, by setting a three-way valve 3, a connecting pipe 6, and a descending connecting pipe 9, enables the system to switch the two sets of tube screens from parallel operation to series operation when the system is at a low load rate. This increases the molten salt flow rate in the tube screen, thereby improving the system stability and reliability under low load conditions and increasing the utilization rate of sunlight.

[0068] In the above scheme, the tube screen component 2 is not limited to two groups, but can be three or more groups.

[0069] In this application, the heat absorber system is generally located on a tower approximately 200m high, while the low-temperature molten salt tank 28 and the high-temperature molten salt tank 26 are located on the ground, connected to the tower via a downcomer 4. Low and high temperatures are relative terms; the high temperature condition satisfies the heat absorption and power supply requirements of the molten salt heat exchanger 27, while the low temperature condition does not. Typically, around 400 degrees Celsius is used as the dividing point between low and high temperatures.

[0070] Molten salt heat exchanger 27 transfers the heat energy carried by molten salt to water or steam to generate high-temperature water or steam. During the heat exchange process, the water is heated to a high temperature, becoming high-temperature water. This high-temperature water can be directly used for heating needs in industrial processes, such as chemical production, heating systems, or hot water supply, thereby saving energy consumption and improving energy efficiency.

[0071] In addition to generating high-temperature water, molten salt heat exchangers can further heat the water to boiling point, producing steam. Steam is a very useful energy carrier, which can be used to drive steam turbines for power generation, or it can be directly supplied to industrial users who need steam, such as those in the paper, textile, and food processing industries.

[0072] When the two sets of pipe screens are operating in parallel under normal conditions, the pipes within the two sets of pipe screen components 2 are independent of each other and do not interfere with each other, which improves the stability of the system during adjustment. At the same time, the downcomer pipes 4 of the two sets of pipe screens are both independent and interconnected, which greatly reduces the risk of blockage and improves the reliability of the system.

[0073] The tube panel assembly 2 is equipped with a solar radiation sensor, which can measure the intensity of sunlight hitting the ground. Therefore, the flow rate can be adjusted at any time according to the sunlight conditions. By ensuring that the flow rate is within the normal range and combining the molten salt temperature in the downcomer 4, it can be determined whether the tube panel assemblies 2 in the system need to be connected in series or in parallel.

[0074] This application describes the working principle and load regulation mechanism of a molten salt tube receiver system for tower-type concentrated solar power generation, particularly the operation adjustment strategy under low load conditions, in order to avoid the risk of molten salt solidification and ensure stable system operation.

[0075] Under normal operating conditions, the receiver system is typically designed to ensure an inlet temperature of approximately 290°C or higher, and a target temperature of 565°C for the tube panel outlet pipe 5, which is at least greater than 400°C. For example, when a 371MWt receiver is operating at full load (i.e., under sufficient sunlight), the flow rate of the receiver (tube panel assembly 2) is set to 929 kg / s to maintain the molten salt velocity in the flow path within the optimal range of 3.5 m / s. This is the optimal flow rate based on the physical properties of the molten salt and system efficiency considerations.

[0076] Taking the 371MWt receiver as an example, when the solar intensity decreases and the system load drops to 30%, the molten salt flow rate is reduced to 30% of the design rated flow rate, approximately 278.7 kg / s, to ensure that the outlet temperature can still be maintained at around 565℃. At this point, the flow velocity drops to 1.05 m / s. Due to the uneven distribution of sunlight on the receiver, some receiver tubes dissipate more heat than they absorb, resulting in a high risk of molten salt solidification and a high probability of receiver tube blockage. To avoid this situation, the system switches to series operation mode via a three-way valve 3, connecting the two or more sets of tube panel assemblies 2 that were originally connected in parallel through a connecting pipe 6. This increases the length of the pipeline through which the molten salt passes, maintaining the necessary flow velocity even at low flow rates (for example, the flow velocity of 1.05 m / s under the aforementioned 30% load condition will be increased to 2.1 m / s), effectively preventing molten salt solidification and ensuring the safe and reliable operation of the system. By switching between these flexible operating modes (parallel to series), the load regulation range of the system can be expanded. In parallel mode, it can cover 30%-110%, while in series mode, it can be further reduced to 15%, which improves the flexibility and adaptability of the entire system and ensures that it can work efficiently and stably under different light intensities.

[0077] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0078] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0079] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," or "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0080] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0081] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A molten salt tube receiver system for tower-type concentrated solar power generation, characterized in that, The absorber system includes an inlet buffer tank (1), multiple sets of tube screen assemblies (2), a three-way valve (3), a downcomer (4), a tube screen outlet pipe (5), a tube screen inlet pipe (7), and a tube screen connecting pipe (6). The inlet buffer tank (1) is connected to multiple sets of tube screen assemblies (2) one by one through multiple tube screen inlet pipes (7) connected to it. Each tube screen inlet pipe (7) is provided with a tube screen regulating valve (8) near the inlet buffer tank (1). One end of each tube screen outlet pipe (5) is connected to the corresponding tube screen assembly (2). The other end of the tube screen outlet pipe (5) corresponding to the tube screen assembly (2) at the beginning or end is directly connected to the corresponding downcomer pipe (4), and the other end of the tube screen outlet pipe (5) corresponding to the other tube screen assembly (2) is connected to one end of the adjacent tube screen connecting pipe (6) through the corresponding three-way valve (3). The other end of the tube-screen connecting pipe (6) is connected to the adjacent tube-screen inlet pipe (7).

2. The molten salt tube receiver system according to claim 1, characterized in that, The adjacent downcomers (4) are connected by multiple downcomer connecting pipes (9), and each downcomer connecting pipe (9) is provided with a downcomer on / off valve (10).

3. The molten salt tube receiver system according to claim 1, characterized in that, The imported buffer tank (1) is horizontal.

4. The molten salt tube receiver system according to claim 1, characterized in that, The heat absorber system also includes a bypass pipe (11) and a riser pipe (12). The riser pipe (12) is located below the inlet buffer tank (1) and is connected to the inlet buffer tank (1). One end of the bypass pipe (11) is connected to the riser pipe (12), and the other end of the bypass pipe (11) is connected to multiple downcomers (4).

5. The molten salt tube receiver system according to claim 4, characterized in that, The absorber system includes an upper connecting pipe (17) and a lower connecting pipe (18). Each group of the tube screen assembly (2) includes multiple tube screens. Each group of adjacent tube screens is connected through the upper connecting pipe (17) or the lower connecting pipe (18). The upper connecting pipe (17) is located at the upper end of the tube screen assembly (2), and the lower connecting pipe (18) is located at the lower end of the tube screen. The upper connecting pipe (17) and the lower connecting pipe (18) are staggered and connected to the adjacent tube screens.

6. The molten salt tube receiver system according to claim 5, characterized in that, The system also includes an exhaust branch pipe (13), an exhaust main pipe (14), an exhaust valve (15), and an exhaust canister (16). One end of the exhaust branch pipe (13) is connected to the upper connecting pipe (17), and the other end of the exhaust branch pipe (13) is connected to the exhaust main pipe (14). The end of the exhaust main pipe (14) passes through the exhaust canister (16) and is connected to the pipe screen outlet pipe (5) or the downcomer pipe (4).

7. The molten salt tube receiver system according to claim 6, characterized in that, The system also includes a salt-draining branch pipe (19), a salt-draining valve (20), and a salt-draining main pipe (21). One end of the salt-draining branch pipe (19) is connected to the pipe screen assembly (2) through the lower connecting pipe (18) or the pipe screen inlet pipe (7). The other end of the salt-draining branch pipe (19) is connected to the salt-draining main pipe (21). One end of the salt-draining main pipe (21) is connected to the pipe screen inlet pipe (7). The end of the salt-draining main pipe (21) is connected to the pipe screen outlet pipe (5) or the downcomer pipe (4) on the corresponding pipe screen assembly (2).

8. The molten salt tube receiver system according to claim 7, characterized in that, The end of the inlet pipe (7) of the tube screen is divided into two branches, namely the first inlet pipe (22) and the second inlet pipe (23). The first inlet pipe (22) is equipped with a first inlet regulating valve (24), and the second inlet pipe (23) is equipped with a second inlet regulating valve (25). The first inlet pipe (22) is connected to the tube screen at the beginning of each group, and the second inlet pipe (23) is connected to the salt-repellent main pipe (21).

9. The molten salt tube receiver system according to claim 8, characterized in that, The system also includes a high-temperature molten salt tank (26), a molten salt heat exchanger (27), a low-temperature molten salt tank (28), a high-temperature molten salt tank regulating valve (29), and a low-temperature molten salt tank regulating valve (30). Each of the downcomers (4) is connected to the high-temperature molten salt tank (26) or the low-temperature molten salt tank (28) respectively through the high-temperature molten salt tank regulating valve (29) or the low-temperature molten salt tank regulating valve (30). The high-temperature molten salt tank (26) is connected to the low-temperature molten salt tank (28) through the molten salt heat exchanger (27), and the low-temperature molten salt tank (28) is connected to the inlet buffer tank (1) through the riser (12).

10. The molten salt tube receiver system according to claim 1, characterized in that, A molten salt flow meter is installed on the outlet pipe (5) of the tube screen.

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