Molten salt condensed water heat exchange system and method

Abstract

The invention discloses a fused salt condensation water heat exchange system and method. The fused salt condensation water heat exchange system comprises a heat storage tank, a heat exchange tank, a cold storage tank, a water supply pipe, a steam generator, a phase change heat storage device and a countercurrent heat exchanger. According to the fused salt condensed water heat exchange system and method, through multi-stage gradient heat exchange, waste heat of the high temperature stage, the medium temperature stage and the low temperature stage can be fully utilized, the fused salt waste heat recovery efficiency is remarkably improved, and originally wasted heat energy is effectively recovered and utilized. And due to the design of multi-stage gradient heat exchange, the whole heat exchange process is more stable, and the problems of temperature fluctuation and system instability possibly caused by a single heat exchange mode are solved. The waste heat of different temperature sections is utilized in respective appropriate links, cascade matching of high-temperature power generation, medium-temperature heat storage and low-temperature recycling is achieved, the waste heat is accurately applied to the most appropriate scene according to the characteristics of the waste heat of different temperatures, the energy grade is utilized to the maximum extent, unreasonable utilization of energy is avoided, and the utilization efficiency of the energy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial heat energy recovery, and in particular to a molten salt condensate heat exchange system and method. Background Art

[0002] In high-energy-consuming industrial fields such as metallurgy and chemical industry, high-temperature molten salt is a product or intermediate medium of the production process (such as aluminum electrolysis waste salt, glass kiln slag, etc.), and its treatment usually aims at safe discharge or storage as the ultimate goal. Existing technologies generally use passive cooling methods such as natural cooling, water quenching or air cooling towers to accelerate the solidification of molten salt through forced convection, radiators and other means to avoid the erosion of storage facilities by high-temperature melt. The core of this method is to achieve the physical state transformation of molten salt (liquid → solid) and temperature reduction to meet subsequent storage or transportation requirements.

[0003] Although the above-mentioned treatment mode can achieve rapid cooling of molten salt, it has significant defects: first, a large amount of heat energy (usually >500℃) contained in the high-temperature molten salt is directly dissipated into the environment, resulting in serious waste of energy resources; in addition, the cooling process lacks consideration of the graded utilization of heat, and the mixed emission of high, medium and low temperature waste heat not only aggravates environmental thermal pollution, but also misses the potential for multi-scenario energy co-supply, restricting the sustainable development of industrial production. For this reason, a molten salt condensate heat exchange system is proposed. Summary of the Invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, the embodiment of the present invention proposes a molten salt condensate heat exchange system and method

[0006] The molten salt condensate heat exchange system of the embodiment of the present invention includes:

[0007] A hot storage tank, a heat exchange tank and a cold storage tank, wherein the hot storage tank, the heat exchange tank and the cold storage tank are connected in sequence, the hot storage tank is used to transport high-temperature molten salt to the heat exchange tank, the heat exchange tank has a high-temperature cavity, a medium-temperature cavity and a low-temperature cavity connected in sequence, the high-temperature molten salt flows through the high-temperature cavity, the medium-temperature cavity and the low-temperature cavity in sequence for heat exchange, and the low-temperature molten salt after heat exchange and cooling is transported to the cold storage tank for storage, and the high-temperature cavity, the medium-temperature cavity and the low-temperature cavity are respectively provided with a first heat exchange tube, a second heat exchange tube and a third heat exchange tube;

[0008] a water supply pipe, the water supply pipe being in communication with water inlets of the first heat exchange pipe, the second heat exchange pipe, and the third heat exchange pipe;

[0009] A steam generator, a phase-change heat storage device, and a countercurrent heat exchanger. The steam generator is connected to the outlet of the first heat exchange tube and is used to receive saturated steam discharged from the first heat exchange tube for power generation. The phase-change heat storage device is connected to the outlet of the second heat exchange tube and is used to receive and store heat in the high-pressure hot water discharged from the second heat exchange tube. The countercurrent heat exchanger is connected to the outlet of the third heat exchange tube and is used to perform countercurrent heat exchange with boiler feed water.

[0010] In some embodiments, the hot storage tank is provided with a feed pipe for conveying high-temperature molten salt into the hot storage tank, a first delivery pump is provided between the hot storage tank and the high-temperature chamber of the heat exchange tank, and the cold storage tank is provided with a second delivery pump for extracting low-temperature molten salt stored in the cold storage tank.

[0011] In some embodiments, the molten salt condensate water heat exchange system of an embodiment of the present invention includes a controller, an electric-controlled valve and a temperature sensor. The electric-controlled valve is respectively arranged at the water inlet of the first heat exchange tube, the second heat exchange tube and the third heat exchange tube, for controlling the water flow rate. The temperature sensor is respectively arranged at the water outlet of the first heat exchange tube, the second heat exchange tube and the third heat exchange tube, for detecting the water temperature. The controller is respectively controlled and connected to the first delivery pump, the electric-controlled valve and the temperature sensor. The controller controls the opening and closing of the electric-controlled valve and the speed of the first delivery pump based on a preset temperature threshold.

[0012] In some embodiments, the controller presets a temperature threshold of 250°C-300°C for the first heat exchange tube, a temperature threshold of 150°C-180°C for the second heat exchange tube, and a temperature threshold of 60°C-90°C for the third heat exchange tube.

[0013] In some embodiments, at least one of the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube is arranged in a serpentine shape within the heat exchange tank.

[0014] In some embodiments, two spaced-apart partition plates are provided in the heat exchange tank to separate the chamber of the heat exchange tank into the high-temperature chamber, the medium-temperature chamber and the low-temperature chamber, and the partition plates have through holes for the flow of molten salt.

[0015] In some embodiments, the through hole is adjacent to the top of the heat exchange tank.

[0016] In some embodiments, a venturi accelerator is provided between the first heat exchange tube and the steam generator, and the venturi accelerator is used to accelerate the saturated steam discharged from the first heat exchange tube and then transport it into the steam generator.

[0017] In some embodiments, the molten salt condensate heat exchange method of the embodiment of the present invention, which is applied to any of the molten salt condensate heat exchange systems described above, includes:

[0018] When the temperature of any one of the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube is higher than a preset upper threshold value, the rotation speed of the first delivery pump is reduced to reduce the molten salt flow rate by 15%-20% to extend the heat exchange time of the high-temperature chamber, and at the same time, the opening of the corresponding electric control valve in the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube is increased by 20%-25%;

[0019] When the temperature of any one of the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube is lower than the lower limit of a preset threshold, the rotation speed of the first delivery pump is increased to increase the molten salt flow rate by 10%-15% to shorten the heat exchange time of the low-temperature chamber. At the same time, the opening degree of the corresponding electric control valve in the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube is 10%-15%, and the flow rate and the adjustment rate of the electric control valve are less than 3% / second.

[0020] In some embodiments, a molten salt target flow rate v (m / s) is defined, where:

[0021]

[0022] Wherein, v is the target flow rate of the molten salt; v0 is the initial flow rate, which is set by the reference speed of the first delivery pump; ΔT=T 实测 -T 阈值 ;

[0023] The opening degree K (%) of the electric control valve is adjusted synchronously according to the following formula:

[0024] K = K0 + βΔT (β = 0.5% / °C)

[0025] Wherein, K is the target opening of the electronically controlled valve (unit: %); K0 is the initial opening of the electronically controlled valve; β is the valve opening adjustment coefficient, which is 0.5% / °C.

[0026] The molten salt condensate heat exchange system and method of the present invention can fully utilize the waste heat of the three stages of high temperature, medium temperature and low temperature through multi-stage gradient heat exchange, significantly improving the molten salt waste heat recovery efficiency, and effectively recovering and utilizing the heat energy that was originally wasted. The design of multi-stage gradient heat exchange makes the entire heat exchange process smoother, avoiding the temperature fluctuations and system instability problems that may be caused by a single heat exchange method. The waste heat of different temperature segments is utilized in their respective appropriate links, which helps to maintain the stable operation of the system. It realizes the cascade matching of high-temperature power generation, medium-temperature heat storage, and low-temperature reuse, and accurately applies the waste heat to the most suitable scenario according to the characteristics of the waste heat at different temperatures, maximizes the utilization of energy grade, avoids the irrational use of energy, and improves the efficiency of energy utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of a molten salt condensate heat exchange system according to an embodiment of the present invention.

[0028] Figure 2 It is a partial structural diagram of the molten salt condensate heat exchange system according to an embodiment of the present invention.

[0029] Figure 3 is a cross-sectional view of a heat exchange tank according to an embodiment of the present invention.

[0030] Figure 4 Schematic diagram of control logic of a controller according to an embodiment of the present invention.

[0031] Figure 5 It is a flow chart of a molten salt condensate heat exchange method of a controller according to an embodiment of the present invention.

[0032] Reference numerals:

[0033] 100. Molten salt condensate heat exchange system; 1. Hot storage tank; 2. Heat exchange tank; 201. High-temperature chamber; 202. Medium-temperature chamber; 203. Low-temperature chamber; 3. Cold storage tank; 4. First heat exchange tube; 5. Second heat exchange tube; 6. Third heat exchange tube; 7. Water supply pipe; 8. Steam generator; 9. Phase change heat storage device; 10. Countercurrent heat exchanger; 11. Feed pipe; 12. First delivery pump; 13. Second delivery pump; 15. Electric control valve; 16. Temperature sensor; 17. Partition plate; 1701. Through hole; 18. Venturi acceleration tube. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0035] like Figures 1 to 5As shown, the molten salt condensate heat exchange system 100 according to an embodiment of the present invention includes a hot storage tank 1, a heat exchange tank 2, a cold storage tank 3, a water supply pipe 9, a steam generator 7, a phase change heat storage device 8, and a countercurrent heat exchanger 9. The hot storage tank 1, heat exchange tank 2, and cold storage tank 3 are sequentially connected. The hot storage tank 1 is used to transport high-temperature molten salt into the heat exchange tank 2. The heat exchange tank 2 has a high-temperature chamber 201, a medium-temperature chamber 202, and a low-temperature chamber 203, which are sequentially connected. The high-temperature molten salt flows through the high-temperature chamber 201, the medium-temperature chamber 202, and the low-temperature chamber 203 in sequence for heat exchange. After heat exchange and cooling, the low-temperature molten salt is transported to the cold storage tank 3 for storage. The first heat exchange tube 4, the second heat exchange tube 5 and the third heat exchange tube 6 are respectively provided in the high-temperature chamber 201, the medium-temperature chamber 202 and the low-temperature chamber 203, and the water supply pipe 9 is connected to the water inlets of the first heat exchange tube 4, the second heat exchange tube 5 and the third heat exchange tube 6 to transport water to the first heat exchange tube 4, the second heat exchange tube 5 and the third heat exchange tube 6.

[0036] The steam generator 7 is connected to the outlet of the first heat exchange tube 4 and is used to receive saturated steam discharged from the first heat exchange tube 4 to generate electricity. The phase change heat storage device 8 is connected to the outlet of the second heat exchange tube 5 and is used to receive and store heat from the high-pressure hot water discharged from the second heat exchange tube 5. The countercurrent heat exchanger 9 is connected to the outlet of the third heat exchange tube 6 and is used to perform countercurrent heat exchange with the boiler feed water.

[0037] When the molten salt condensate heat exchange system 100 of the present invention is in use, the heat storage tank 1 stores high-temperature molten salt and transfers it to the heat exchange tank 2. The heat exchange tank 2 is provided with a high-temperature chamber 201, a medium-temperature chamber 202, and a low-temperature chamber 203, which are sequentially connected. The high-temperature molten salt first enters the high-temperature chamber 201 to exchange heat with the water in the first heat exchange tube 4, converting the water into saturated steam. The saturated steam is then discharged from the outlet of the first heat exchange tube 4 and transferred to the steam generator 7 for power generation.

[0038] After heat exchange in high-temperature chamber 201, the molten salt enters medium-temperature chamber 202. Second heat exchange tube 5 within medium-temperature chamber 202 also receives water from water supply pipe 9. The molten salt exchanges heat with the water in second heat exchange tube 5, converting the water into high-pressure hot water. The high-pressure hot water is discharged from the outlet of second heat exchange tube 5 and transported to phase-change heat storage device 8, which stores the heat.

[0039] After heat exchange in medium-temperature chamber 202, the molten salt enters low-temperature chamber 203. Third heat exchange tube 6 in low-temperature chamber 203 receives water from water supply pipe 9. The molten salt exchanges heat with the water in third heat exchange tube 6. The water discharged from the outlet of third heat exchange tube 6 enters countercurrent heat exchanger 9, where it undergoes countercurrent heat exchange with boiler feed water. After three stages of heat exchange and cooling, the low-temperature molten salt is transferred to cold storage tank 3 for storage.

[0040] The molten salt condensate heat exchange system 100 of the present invention can fully utilize the waste heat of the three stages of high temperature, medium temperature and low temperature through multi-stage gradient heat exchange, significantly improving the molten salt waste heat recovery efficiency, and effectively recovering and utilizing the heat energy that was originally wasted. The design of multi-stage gradient heat exchange makes the entire heat exchange process smoother, avoiding the temperature fluctuations and system instability problems that may be caused by a single heat exchange method. The waste heat of different temperature segments is utilized in their respective appropriate links, which helps to maintain the stable operation of the system. It realizes the cascade matching of high-temperature power generation, medium-temperature heat storage, and low-temperature reuse. According to the waste heat characteristics of different temperatures, it is accurately applied to the most suitable scenario, maximizing the utilization of energy grade, avoiding the irrational use of energy, and improving the efficiency of energy utilization.

[0041] Specifically, both the hot storage tank 1 and the cold storage tank 3 are cylindrical high-temperature pressure vessels lined with ceramic fiber insulation. The heat exchange pipe tank 2 is a horizontal double-layer shell structure with an outer layer of carbon steel and an inner layer of 316L stainless steel. The high-temperature molten salt is at a temperature of approximately 350°C, while the low-temperature molten salt is below 100°C.

[0042] Optionally, the hot storage tank 1 is provided with a feed pipe 10 for conveying high-temperature molten salt into the hot storage tank 1, a first delivery pump 11 is provided between the hot storage tank 1 and the high-temperature chamber 201 of the heat exchange tank 2, and the cold storage tank 3 is provided with a second delivery pump 12 for extracting low-temperature molten salt stored in the cold storage tank 3.

[0043] In some embodiments, the molten salt condensate heat exchange system 100 of the present invention includes a controller 13, an electrically controlled valve 14, and a temperature sensor 15. The electrically controlled valves 14 are respectively located at the water inlets of the first heat exchange tube 4, the second heat exchange tube 5, and the third heat exchange tube 6 to control the water flow rate. The temperature sensors 15 are respectively located at the water outlets of the first heat exchange tube 4, the second heat exchange tube 5, and the third heat exchange tube 6 to detect the water temperature. The controller 13 is respectively connected to the first delivery pump 11, the electrically controlled valve 14, and the temperature sensor 15. The controller 13 controls the opening and closing of the electrically controlled valve 14 and the speed of the first delivery pump 11 based on a preset temperature threshold.

[0044] Specifically, hot storage tank 1 transports high-temperature molten salt to high-temperature chamber 201, medium-temperature chamber 202, and low-temperature chamber 203 of heat exchange tank 2. The high-temperature molten salt sequentially exchanges heat with the water in first heat exchange tube 4, second heat exchange tube 5, and third heat exchange tube 6. After heat exchange, the low-temperature molten salt is transported to cold storage tank 3 for storage. The saturated steam and high-pressure hot water generated by the different heat exchange tubes are used for power generation, heat storage, and heat exchange with boiler feed water.

[0045] Temperature sensors 15 are located at the outlets of the first, second, and third heat exchange tubes 4, 5, and 6, respectively. They monitor the water temperature at each outlet in real time and transmit this temperature data to the controller 13. The controller 13 pre-sets temperature thresholds. Upon receiving the water temperature data from the temperature sensors 15, the controller compares the actual water temperature with the preset thresholds. For example, if the water temperature at a particular heat exchange tube outlet exceeds the preset threshold, it indicates that the current water flow rate may be insufficient to remove sufficient heat. If the water temperature is below the preset threshold, it indicates that the water flow rate may be excessive.

[0046] Based on the results of the comparative analysis, controller 13 issues control commands to the corresponding electrically controlled valves 14 and first delivery pump 11. For electrically controlled valves 14, controller 13 adjusts their opening and closing to control the water flow into each heat exchange tube. For first delivery pump 11, controller 13 adjusts its speed to vary the water delivery rate of the entire system, thereby ensuring that the water temperature within each heat exchange tube remains stable within a preset, appropriate range.

[0047] By intelligently controlling the water flow in each heat exchange tube, the water in each tube and the high-temperature molten salt undergo a more precise heat exchange. When the water temperature is too high, increasing the water flow allows for more complete absorption of the molten salt's heat; when the water temperature is too low, reducing the water flow prevents unnecessary water waste, further improving the efficiency of molten salt waste heat recovery.

[0048] Intelligent collaborative control monitors and adjusts system operating parameters in real time, effectively addressing various temperature changes and fluctuations during system operation. By precisely controlling water flow and pump speed, it maintains stability in each heat exchange link, avoiding system failures caused by abnormal water temperatures and significantly enhancing system operational stability.

[0049] The introduction of a dynamic temperature control algorithm enables the system to make real-time adjustments based on actual temperature conditions, more accurately achieving a cascaded matching of high-temperature power generation, medium-temperature heat storage, and low-temperature reuse. This ensures that waste heat in each temperature range is accurately utilized in the most appropriate scenario, further improving energy utilization.

[0050] The adaptive piping structure, combined with a dynamic temperature control algorithm, precisely controls the water temperature within each heat exchange tube, preventing vaporization caused by excessive water temperature and corrosion due to temperature anomalies. This extends the life of the equipment and reduces maintenance and replacement costs.

[0051] The system's integrated design combines multi-stage gradient heat exchange with intelligent collaborative control, making the entire system more compact, easier to operate, and streamlining the operation and maintenance process. Furthermore, precise control reduces unnecessary energy consumption and overall energy consumption, providing a more efficient and safe solution for industrial waste heat recovery and renewable energy consumption, and effectively promoting the green and low-carbon transformation of industry.

[0052] In some embodiments, the preset temperature threshold of the controller 13 for the first heat exchange tube 4 is 250℃-300℃, the preset temperature threshold of the controller 13 for the second heat exchange tube 5 is 150℃-180℃, and the preset temperature threshold of the controller 13 for the third heat exchange tube 6 is 60℃-90℃.

[0053] Temperature sensor 15 continuously monitors the water temperature at the outlets of the first, second, and third heat exchange tubes and transmits this data to controller 13. When the water temperature at the outlet of first heat exchange tube 4 falls below 250°C, controller 13 determines the water temperature is too low and issues a command to increase the opening of electrically controlled valve 14 at the corresponding water inlet, increasing the water flow rate and allowing the water to absorb more heat from the high-temperature molten salt, raising the water temperature. If the water temperature exceeds 300°C, controller 13 controls electrically controlled valve 14 to decrease its opening, reducing the water flow rate and preventing the excessive water temperature from affecting the stability of the subsequent steam power generation process.

[0054] For the second heat exchange tube 5, when the water temperature at the water outlet is lower than 150°C, the controller 13 controls the electric control valve 14 to increase the water flow rate and raise the water temperature to meet the heat demand of the phase change heat storage device 8; if the water temperature is higher than 180°C, the water flow rate is reduced to ensure that the water temperature is within the appropriate range, which is conducive to the effective storage of heat.

[0055] For the third heat exchange tube 6, when the water temperature at the outlet is lower than 60°C, the controller 13 increases the water flow rate to ensure that as much heat as possible can be absorbed from the low-temperature molten salt; if the water temperature is higher than 90°C, the water flow rate is reduced to maintain a suitable temperature difference and heat exchange efficiency during countercurrent heat exchange with the boiler feed water.

[0056] Specific preset temperature thresholds are set for different application scenarios, allowing the system to precisely adapt to the diverse needs of high-temperature power generation, medium-temperature heat storage, and low-temperature reuse. For example, the temperature range of 250°C-300°C for the first heat exchange tube 4 ensures that the generated saturated steam has appropriate parameters, improving the power generation efficiency of the steam generator 7; the temperature of 150°C-180°C for the second heat exchange tube 5 provides stable and suitable heat storage conditions for the phase change heat storage device 8; and the temperature of 60°C-90°C for the third heat exchange tube 6 facilitates effective countercurrent heat exchange with the boiler feed water.

[0057] By precisely controlling the water temperature of each heat exchange tube, the cascade utilization of energy is further optimized. This avoids energy loss caused by inappropriate water temperature and enables efficient and reasonable utilization of the waste heat of high-temperature molten salt in different temperature ranges, thereby improving the energy conversion efficiency and energy utilization rate of the entire system.

[0058] Appropriate preset temperature thresholds help ensure the normal operation of various devices. For example, controlling the water temperature in the first heat exchange tube 4 within a reasonable range can prevent damage to the steam generator 7 due to abnormal steam parameters. Controlling the water temperature in the second heat exchange tube 5 promotes the stable operation and service life of the phase change heat storage device 8. Controlling the water temperature in the third heat exchange tube 6 ensures the heat transfer efficiency and equipment safety of the countercurrent heat exchanger 9.

[0059] Intelligent control based on specific temperature thresholds enhances system reliability. The system automatically adjusts to real-time water temperature, effectively responding to varying operating conditions. This reduces the risk of system failures due to temperature fluctuations and improves overall system reliability and stability.

[0060] In some embodiments, at least one of the first heat exchange tube 4 , the second heat exchange tube 5 and the third heat exchange tube 6 is arranged in a serpentine shape within the heat exchange tank 2 .

[0061] When the high-temperature molten salt flows in the high-temperature chamber 201, the medium-temperature chamber 202, and the low-temperature chamber 203 of the heat exchange tank 2, the serpentine-shaped heat exchange tube increases the flow path and residence time of the water in the heat exchange tank 2. The water supply pipe 9 transports water to the serpentine-shaped heat exchange tube. During the flow of water in the tube, the path becomes longer and the flow direction is constantly changed, which greatly increases the contact area and contact time between the water and the surrounding high-temperature molten salt. In this way, the water can more fully absorb the heat of the high-temperature molten salt and achieve more efficient heat exchange. At the same time, under the intelligent control system, combined with the temperature sensor 15 and the controller 13 to adjust the water flow, the serpentine-shaped heat exchange tube can better adapt to different working conditions and ensure the stability and efficiency of the heat exchange process.

[0062] Optionally, the first heat exchange tube 4 is a DN80 stainless steel tube with 20 serpentine bends; the second heat exchange tube 5 is a DN50 stainless steel tube with 15 serpentine bends; and the third heat exchange tube 6 is a DN32 stainless steel tube with 120 serpentine bends.

[0063] In some embodiments, two spaced-apart partition plates 16 are provided in the heat exchange tank 2 to separate the chamber of the heat exchange tank 2 into a high-temperature chamber 201 , a medium-temperature chamber 202 and a low-temperature chamber 203 . The partition plates 16 have through holes 1601 for the molten salt to flow.

[0064] In the molten salt condensate heat exchange system 100, two spaced-apart partitions 16 are installed within the heat exchange tank 2, dividing the chamber into a high-temperature chamber 201, a medium-temperature chamber 202, and a low-temperature chamber 203. The partitions 16 have through-holes 1601 for the molten salt to flow through. When the hot storage tank 1 transfers high-temperature molten salt to the heat exchange tank 2, the high-temperature molten salt first enters the high-temperature chamber 201. Within this chamber, the high-temperature molten salt exchanges heat with the water in the first heat exchange tube 4, releasing a large amount of heat. The molten salt then flows through the through-holes 1601 in the partition 16 into the medium-temperature chamber 202. In the medium-temperature chamber 202, the molten salt continues to exchange heat with the water in the second heat exchange tube 5, further lowering its temperature. Finally, the molten salt enters the low-temperature chamber 203 through the through-holes 1601 in the other partition 16, completing the final heat exchange with the water in the third heat exchange tube 6. After becoming low-temperature molten salt, it is transferred to the cold storage tank 3 for storage. During the entire process, the arrangement of the partition plate 16 and the through-holes 1601 guides the molten salt to pass through chambers of different temperatures in sequence, thereby achieving orderly multi-stage heat exchange.

[0065] Divider plate 16 clearly divides heat exchange tank 2 into chambers with different temperature zones, allowing the high-temperature molten salt to exchange heat in a sequence of high temperature, medium temperature, and low temperature. This design ensures that the system can achieve multi-stage gradient heat exchange, utilizing waste heat at different temperature stages separately and improving waste heat recovery efficiency. Compared with heat exchange in an undivided single chamber, multi-stage gradient heat exchange can more accurately match the waste heat utilization requirements of different temperatures, such as using high temperature for power generation, medium temperature for heat storage, and low temperature for reuse.

[0066] The presence of partitions 16 makes each chamber relatively independent, preventing molten salts from different temperature zones from mixing and ensuring a relatively stable temperature within each chamber. This helps improve the stability and controllability of heat exchange, allowing the water in each heat exchange tube to exchange heat with the molten salt in a relatively stable temperature environment, thereby improving the stability and reliability of system operation.

[0067] By separating the chambers using partition plates 16, the temperature variation of the molten salt in each chamber can be more precisely controlled, thereby achieving a cascaded matching of high-temperature power generation, medium-temperature heat storage, and low-temperature reuse. This ensures that waste heat at different temperatures is utilized in the most appropriate scenario, maximizing energy utilization and reducing energy waste.

[0068] In some embodiments, the through hole 1601 is adjacent to the top of the heat exchange tank 2 .

[0069] When the heat storage tank 1 transports the high-temperature molten salt to the heat exchange tank 2, since the through-hole 1601 is close to the top of the heat exchange tank 2, the high-temperature molten salt will first gather in the lower part of the corresponding chamber of the heat exchange tank 2. In the lower part, the molten salt is in full contact with the heat exchange tube for heat exchange. As the molten salt continues to flow in, the temperature of the molten salt in the lower part gradually decreases, and the newly flowing high-temperature molten salt will continue to replenish the lower part. When the molten salt liquid level rises to a position close to the through-hole 1601 at the top of the heat exchange tank 2, the molten salt that has been cooled to a certain extent will flow into the next chamber through the through-hole 1601. This flow method ensures that the molten salt has enough time and space in each chamber to fully exchange heat with the water in the heat exchange tube, thereby achieving effective heat transfer.

[0070] In some embodiments, a venturi accelerator tube 17 is provided between the first heat exchange tube 4 and the steam generator 7 . The venturi accelerator tube 17 is used to accelerate the saturated steam discharged from the first heat exchange tube 4 and then transport it to the steam generator 7 .

[0071] For example, the Venturi accelerator tube 17 increases the flow rate of saturated steam from 15m / s to 35m / s. The Venturi accelerator tube 17 has a special structure, and its diameter gradually shrinks and then gradually expands. When the saturated steam enters the part with a reduced diameter, according to the continuity equation in fluid mechanics (in a steady flow, the mass flow rate of the fluid remains unchanged in each cross section of the pipeline), the flow rate will increase and the pressure will decrease; while in the part with an expanded diameter, the steam flow rate is further stabilized and maintained at a higher speed. In this way, the Venturi accelerator tube 17 accelerates the saturated steam discharged from the first heat exchange tube 4. The accelerated saturated steam is transported to the steam generator 7, and the high-speed steam impacts the blades of the steam generator 7, driving the generator rotor to rotate, thereby converting the kinetic energy of the steam into electrical energy.

[0072] Accelerated saturated steam has higher kinetic energy. When it strikes the blades of the steam generator 7, it causes the blades to rotate faster, increasing the generator's output power. Compared to unaccelerated steam, it can more efficiently convert thermal energy into electrical energy, thereby improving the power generation efficiency of the entire system and making better use of high-temperature waste heat.

[0073] In some embodiments, a molten salt condensate heat exchange method according to an embodiment of the present invention, which is applied to any of the above-mentioned molten salt condensate heat exchange systems 100, includes:

[0074] When the temperature of any one of the first heat exchange tube 4, the second heat exchange tube 5, and the third heat exchange tube 6 exceeds the preset upper threshold, the rotation speed of the first delivery pump 11 is reduced, reducing the molten salt flow rate by 15%-20% to extend the heat exchange time of the high-temperature chamber 201. At the same time, the opening of the corresponding electric control valve 14 in the first heat exchange tube 4, the second heat exchange tube 5, and the third heat exchange tube 6 is increased by 20%-25%.

[0075] When the temperature of any one of the first heat exchange tube 4, the second heat exchange tube 5, and the third heat exchange tube 6 falls below a preset lower threshold, the speed of the first delivery pump 11 is increased, increasing the molten salt flow rate by 10%-15%, thereby shortening the heat exchange time in the low-temperature chamber 203. Simultaneously, the openings of the corresponding electrically controlled valves 14 in the first heat exchange tube 4, the second heat exchange tube 5, and the third heat exchange tube 6 are adjusted by 10%-15%, and the flow rate and the adjustment rate of the electrically controlled valves 14 are less than 3% / second.

[0076] This molten salt condensate heat exchange method is implemented based on the molten salt condensate heat exchange system 100. Its core lies in dynamically adjusting the flow rate of the molten salt and the opening of the electric control valve 14 at the water inlet of each heat exchange tube according to the actual water temperature of each heat exchange tube, so as to ensure stable and efficient operation of the system. The details are as follows:

[0077] When the temperature sensor 15 detects that the temperature of any of the first, second, and third heat exchange tubes is higher than the preset threshold upper limit, the controller 13 receives the temperature signal. The controller 13 first reduces the rotation speed of the first delivery pump 11, reducing the flow rate of the molten salt in the heat exchange tank 2 by 15%-20%. After the flow rate is reduced, the residence time of the molten salt in the high-temperature chamber 201 is extended, thereby having more time to exchange heat with the water in the heat exchange tube, avoiding excessive heat transfer and causing the water temperature to be too high. At the same time, the controller 13 increases the opening of the electric control valve 14 at the water inlet of the corresponding heat exchange tube by 20%-25%, increasing the water flow rate, allowing more water to participate in the heat exchange, taking away more heat, and lowering the water temperature.

[0078] When temperature sensor 15 detects that the temperature of any heat exchange tube falls below a preset lower threshold, controller 13 increases the speed of first delivery pump 11, increasing the molten salt flow rate by 10%-15%. This shortens the heat exchange time of the molten salt in low-temperature chamber 203 and reduces heat loss during the low-temperature phase. Simultaneously, the opening of electrically controlled valve 14 at the water inlet of the corresponding heat exchange tube is reduced by 10%-15%, reducing the water flow rate, allowing the water to absorb more heat and raising the water temperature. To prevent damage to the equipment caused by excessive changes in system parameters, the flow rate and the adjustment rate of electrically controlled valve 14 are controlled to less than 3% / second.

[0079] By monitoring the water temperature of each heat exchange tube in real time and dynamically adjusting the molten salt flow rate and water flow rate based on temperature conditions, the water temperature of each heat exchange tube can be precisely controlled within a preset appropriate range. This helps improve waste heat recovery efficiency, ensuring that high-temperature power generation, medium-temperature heat storage, and low-temperature reuse can all be carried out under optimal temperature conditions, achieving efficient cascaded energy utilization.

[0080] The molten salt flow rate and water flow rate are adjusted slowly and steadily (at a rate of less than 3% / second), avoiding large fluctuations in system parameters, reducing the impact on equipment caused by rapid temperature changes, and enhancing the stability and reliability of system operation. This helps extend the service life of the equipment and reduce maintenance costs and failure rates.

[0081] When the water temperature is too high, the heat exchange time in high-temperature chamber 201 is extended and the water flow rate is increased to fully utilize the high-temperature waste heat. When the water temperature is too low, the heat exchange time in low-temperature chamber 203 is shortened and the water flow rate is reduced to avoid excessive heat loss. This precise adjustment based on actual conditions optimizes the energy utilization efficiency of the entire system and increases the value of energy utilization.

[0082] In some embodiments, a molten salt target flow rate v (m / s) is defined, where:

[0083]

[0084] Wherein, v is the target flow rate of the molten salt; v0 is the initial flow rate, which is set by the reference speed of the first delivery pump;

[0085] ΔT=T 实测 -T 阈值 ;

[0086] The opening degree K (%) of the electric control valve is adjusted synchronously according to the following formula:

[0087] K = K0 + βΔT (β = 0.5% / °C)

[0088] Wherein, K is the target opening of the electric control valve (unit: %); K0 is the initial opening of the electric control valve; β is the valve opening adjustment coefficient, which is 0.5% / °C.

[0089] Adjustment rate ≤ 3% / second, full stroke time ≤ 5 seconds.

[0090] Specifically, when the molten salt condensate heat exchange system of the embodiment of the present invention is in use, the first delivery pump 12 is started to transfer the high-temperature molten salt at 380°C in the heat storage tank 1 at a rate of 25m 3 / h flow rate is pumped into the high temperature chamber 201 of the heat exchange tank 2, and the initial flow rate is set to 2.0m / s. The low temperature molten salt with a temperature of 150℃ in the cold storage tank 3 is pumped into the high temperature chamber 201 of the heat exchange tank 2 by the second delivery pump 13 at a flow rate of 12m / s. 3 / h flow rate discharge to avoid overloading. The water supply pipe 7 injects 25℃ cold water into the first heat exchange tube 4, the second heat exchange tube 5 and the third heat exchange tube 6. The initial flow rate is set to 40m3 / h by the electric control valve 15. 3 / h、30m 3 / h and 20m 3 / h.

[0091] As the high-temperature molten salt flows through the high-temperature chamber 201, it exchanges heat with the first heat exchange tube 4, transferring the heat to the high-pressure water within the tube, which has a design pressure of 4.0 MPa. The water absorbs the heat within the first heat exchange tube 4, rising to a temperature of 250°C-300°C, generating saturated steam at a stable pressure of 4.0 MPa. As the saturated steam passes through the Venturi accelerator tube 18, its throat diameter shrinks to 25 mm, increasing its flow rate from 25 m / s to 35 m / s. This steam then drives the steam generator 8, generating electricity with a power generation efficiency of 35%.

[0092] After releasing heat, the molten salt temperature drops from 380°C to 200°C, flowing into the medium-temperature chamber 202 through the through-hole 1701 at the top of the partition plate 17 between the high-temperature chamber 201 and the medium-temperature chamber 202. The 200°C molten salt exchanges heat with the second heat exchange tube 5 within the medium-temperature chamber 20, heating the water in the tube to 170°C (at a pressure of 0.8 MPa), generating high-pressure hot water. This high-pressure hot water is then transported to the phase-change heat storage device 9, releasing latent heat to heat the heat storage medium within the phase-change heat storage device 9 for energy storage.

[0093] When the molten salt flows into low-temperature chamber 203, its temperature drops further to 150°C. Inside low-temperature chamber 203, it exchanges heat with third heat exchange tube 6, heating atmospheric-pressure cold water to 85°C. This hot water is then transported to countercurrent heat exchanger 10, where it undergoes countercurrent heat exchange with boiler feed water (20°C), raising the outlet water temperature to 65°C, thus saving coal.

[0094] The temperature data is transmitted to the controller via a 4-20mA signal and is refreshed every 0.1 seconds.

[0095] Taking the first heat exchange tube 4 as an example, the controller performs over-temperature control.

[0096] The fluctuation of the molten salt flow rate causes the temperature of the first heat exchange tube 4 to rise to 320°C (the upper threshold value is 300°C), ΔT=+20°C.

[0097] Algorithm execution:

[0098] The controller calculates the target flow rate and valve opening according to the formula:

[0099] v=2.0×(1-0.015×20)=1.4m / s

[0100] K = 60% + 0.6 × 20 = 72%

[0101] The rotation speed of the first delivery pump 12 is reduced from 1800 rpm to 1260 rpm (flow rate 2.0 m / s→1.4 m / s), and the opening of the electric control valve 15 on the first heat exchange tube 4 is linearly increased from 60% to 72%;

[0102] The molten salt residence time is extended from 8 minutes to 11 minutes to fully release the heat;

[0103] Cooling water flow from 40m 3 / h increased to 48m 3 / h, and the temperature drops to 295℃ within 3 seconds.

[0104] Taking the third heat exchange tube 6 as an example, the controller performs low temperature control.

[0105] The decrease in ambient temperature causes the temperature of the third heat exchange tube 6 to drop to 75°C (lower threshold 90°C), ΔT = -15°C;

[0106] Algorithm execution:

[0107] The controller calculates the target parameters according to the formula:

[0108] v=1.2×(1+0.012×15)=1.42m / s

[0109] K = 50% + 0.6 × (-15) = 41%

[0110] The speed of the first delivery pump 12 increases from 1000 rpm to 1180 rpm (flow rate 1.2→1.42 m / s), and the opening of the electric control valve 15 decreases from 50% to 41%;

[0111] The residence time of molten salt is shortened by 15%, and the cold water flow rate is reduced from 20m 3 / h reduced to 17m 3 / h, and the temperature returned to 87°C within 2 seconds.

[0112] Over-temperature emergency protection:

[0113] When the temperature of any one of the first heat exchange tube 4, the second heat exchange tube 5 and the third heat exchange tube 6 exceeds the upper threshold by 20% (e.g. the first heat exchange tube 4>360°C), the controller triggers:

[0114] The electric control valve 15 is fully opened to maximize the cooling water flow;

[0115] The first delivery pump 12 is shut down, and the flow of molten salt is interrupted;

[0116] The sound and light alarms are activated and the system switches to safe mode.

[0117] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0118] Furthermore, 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0119] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0120] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0121] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0122] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A molten salt condensate heat exchange system, characterized in that: include: A hot storage tank, a heat exchange tank and a cold storage tank, wherein the hot storage tank, the heat exchange tank and the cold storage tank are connected in sequence, the hot storage tank is used to transport high-temperature molten salt to the heat exchange tank, the heat exchange tank has a high-temperature cavity, a medium-temperature cavity and a low-temperature cavity connected in sequence, the high-temperature molten salt flows through the high-temperature cavity, the medium-temperature cavity and the low-temperature cavity in sequence for heat exchange, and the low-temperature molten salt after heat exchange and cooling is transported to the cold storage tank for storage, and the high-temperature cavity, the medium-temperature cavity and the low-temperature cavity are respectively provided with a first heat exchange tube, a second heat exchange tube and a third heat exchange tube; a water supply pipe, the water supply pipe being in communication with water inlets of the first heat exchange pipe, the second heat exchange pipe, and the third heat exchange pipe; A steam generator, a phase-change heat storage device, and a countercurrent heat exchanger. The steam generator is connected to the outlet of the first heat exchange tube and is used to receive saturated steam discharged from the first heat exchange tube for power generation. The phase-change heat storage device is connected to the outlet of the second heat exchange tube and is used to receive and store heat in the high-pressure hot water discharged from the second heat exchange tube. The countercurrent heat exchanger is connected to the outlet of the third heat exchange tube and is used to perform countercurrent heat exchange with boiler feed water.

2. The molten salt condensate heat exchange system according to claim 1, characterized in that: The hot storage tank is provided with a feed pipe for conveying high-temperature molten salt into the hot storage tank, a first conveying pump is provided between the hot storage tank and the high-temperature cavity of the heat exchange tank, and the cold storage tank is provided with a second conveying pump for extracting low-temperature molten salt stored in the cold storage tank.

3. The molten salt condensate heat exchange system according to claim 2, characterized in that: It includes a controller, an electric-controlled valve and a temperature sensor. The electric-controlled valves are respectively arranged at the water inlets of the first heat exchange tube, the second heat exchange tube and the third heat exchange tube for controlling the water flow rate. The temperature sensors are respectively arranged at the water outlets of the first heat exchange tube, the second heat exchange tube and the third heat exchange tube for detecting the water temperature. The controller is respectively controlled and connected to the first delivery pump, the electric-controlled valve and the temperature sensor. The controller controls the opening and closing of the electric-controlled valve and the speed of the first delivery pump based on a preset temperature threshold.

4. The molten salt condensate heat exchange system according to claim 3, characterized in that: The controller presets a temperature threshold of 250°C-300°C for the first heat exchange tube, a temperature threshold of 150°C-180°C for the second heat exchange tube, and a temperature threshold of 60°C-90°C for the third heat exchange tube.

5. The molten salt condensate heat exchange system according to claim 3, characterized in that: At least one of the first heat exchange tube, the second heat exchange tube and the third heat exchange tube is arranged in a serpentine shape in the heat exchange tank.

6. The molten salt condensate heat exchange system according to claim 3, characterized in that: Two spaced-apart partition plates are provided in the heat exchange tank to divide the chamber of the heat exchange tank into the high-temperature chamber, the medium-temperature chamber and the low-temperature chamber. The partition plates have through holes for the molten salt to flow.

7. The molten salt condensate heat exchange system according to claim 6, characterized in that: The through hole is adjacent to the top of the heat exchange tank.

8. The molten salt condensate heat exchange system according to claim 3, characterized in that: A venturi accelerating tube is provided between the first heat exchange tube and the steam generator, and the venturi accelerating tube is used to accelerate the saturated steam discharged from the first heat exchange tube and then transport it into the steam generator.

9. A molten salt condensate heat exchange method, characterized in that: The method is applied to the molten salt condensate heat exchange system according to any one of claims 3 to 8, comprising: When the temperature of any one of the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube is higher than a preset upper threshold value, the rotation speed of the first delivery pump is reduced to reduce the molten salt flow rate by 15%-20% to extend the heat exchange time of the high-temperature chamber, and at the same time, the opening of the corresponding electric control valve in the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube is increased by 20%-25%; When the temperature of any one of the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube is lower than the lower limit of a preset threshold, the rotation speed of the first delivery pump is increased to increase the molten salt flow rate by 10%-15% to shorten the heat exchange time of the low-temperature chamber. At the same time, the opening degree of the corresponding electric control valve in the first heat exchange tube, the second heat exchange tube, and the third heat exchange tube is 10%-15%, and the flow rate and the adjustment rate of the electric control valve are less than 3% / second.

10. The molten salt condensate heat exchange method according to claim 9, characterized in that: Define the molten salt target flow rate v (m / s), where: Wherein, v is the target flow rate of the molten salt; v0 is the initial flow rate, which is set by the reference speed of the first delivery pump; ΔT=T 实测 -T 阈值 ; The opening degree K (%) of the electric control valve is adjusted synchronously according to the following formula: K = K0 + βΔT (β = 0.5% / °C) Wherein, K is the target opening of the electronically controlled valve (unit: %); K0 is the initial opening of the electronically controlled valve; β is the valve opening adjustment coefficient, which is 0.5% / °C.

Images