Fused salt heat storage and carbon capture synergistic coupling system and control method

Abstract

The invention discloses a molten salt heat storage and carbon capture synergistic coupling system and a control method, and belongs to the technical field of energy conservation and consumption reduction of coal-fired units. The system comprises a fused salt heat storage unit, a heat exchange module, a smoke exhaust pipeline, an amine liquid circulation carbon capture module and a control unit, the control unit is connected with the fused salt heat storage unit, the heat exchange module and the amine liquid circulation carbon capture module; the heat exchange module is integrated with a group of shell-and-tube heat exchangers, the shell side of each shell-and-tube heat exchanger is connected with the fused salt heat storage unit, and the tube side of each shell-and-tube heat exchanger is connected with the amine liquid circulation carbon capture module; the fused salt heat storage unit comprises a low-temperature fused salt tank, a first fused salt circulating pump, a waste heat boiler, a second fused salt circulating pump and a fused salt heat storage tank; a three-way valve is arranged at a fused salt inlet of the heat exchange module and used for controlling the flow direction of fused salt; a smoke inlet of the waste heat boiler is connected with a smoke exhaust pipeline, a fused salt inlet of the waste heat boiler is connected with an outlet of the low-temperature fused salt tank through a first fused salt circulating pump, and a fused salt outlet of the waste heat boiler is connected with an inlet of the fused salt heat storage tank and a three-way valve. An outlet of the fused salt heat storage tank is connected with a three-way valve through a second fused salt circulating pump; a fused salt outlet of the heat exchange module is connected with an inlet of the low-temperature fused salt tank. According to the fused salt heat storage and carbon capture collaborative coupling system and the control method, the framework is simplified, control is convenient and fast, and the feasibility is high.

Description

Technical Field

[0001] This invention belongs to the field of energy conservation and consumption reduction technology for coal-fired power units, specifically relating to a coupled system and control method for synergistic molten salt thermal storage and carbon capture. Background Technology

[0002] The current amine absorption carbon capture system for thermal power units has three major technical problems: poor heat source stability, serious energy waste, and complex control logic. These problems mainly stem from the load fluctuation characteristics of thermal power units, the limitations of the physicochemical properties of amine solutions, the defects of traditional system integration methods, and the complex characteristics of industrial waste gas.

[0003] Among these issues, the poor heat source stability stems from fluctuations in thermal power load (such as flue gas temperature dropping to 280-320℃ during low loads), leading to insufficient heat source for the carbon capture and regeneration tower, with capture rate fluctuations reaching 5-10%, and even triggering system shutdowns. The serious energy waste problem arises from the fact that in traditional schemes, the thermal storage system and the carbon capture system operate independently. Thermal storage is only used for power generation peak shaving, while carbon capture extracts heat solely from thermal power, resulting in 2-3 heat exchange losses and a waste heat utilization rate of only about 60%. Furthermore, the system occupies a large area and has high investment costs. The complex control logic problem stems from the fact that existing coupling schemes require multi-loop coordination, rely on complex algorithms, and are difficult to debug on-site, making them unsuitable for promotion in small and medium-sized units. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a coupled system and control method for molten salt thermal storage and carbon capture, which has a simplified architecture, convenient control and strong implementability.

[0005] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a coupled system for molten salt thermal storage and carbon capture, comprising a molten salt thermal storage unit, a heat exchange module, a flue gas duct, an amine liquid circulation carbon capture module, and a control unit. The control unit is connected to the molten salt thermal storage unit, the heat exchange module, and the amine liquid circulation carbon capture module. The heat exchange module integrates a set of shell-and-tube heat exchangers, with the shell side of the shell-and-tube heat exchangers connected to the molten salt thermal storage unit and the tube side connected to the amine liquid circulation carbon capture module. The molten salt thermal storage unit includes a cryogenic molten salt tank, a first molten salt circulation pump, a waste heat boiler, a second molten salt circulation pump, and the molten salt thermal storage tank. A three-way valve is installed at the molten salt inlet of the heat exchange module to control the molten salt flow direction. The flue gas inlet of the waste heat boiler is connected to the flue gas duct, and the molten salt inlet of the waste heat boiler is connected to the outlet of the cryogenic molten salt tank via the first molten salt circulation pump. The molten salt outlet of the waste heat boiler is connected to the inlet of the molten salt thermal storage tank and the three-way valve. The outlet of the molten salt thermal storage tank is connected to the three-way valve via the second molten salt circulation pump. The molten salt outlet of the heat exchange module is connected to the inlet of the cryogenic molten salt tank.

[0006] In one embodiment, a pressure sensor is provided at the molten salt outlet of the heat exchange module.

[0007] In one embodiment, a temperature sensor is provided at the bottom of the molten salt thermal storage tank.

[0008] In one embodiment, the flue gas outlet of the waste heat boiler is connected to the amine liquid circulation carbon capture module; the molten salt outlet of the heat exchange module is connected to the amine liquid circulation carbon capture module.

[0009] In one embodiment, the amine liquid circulating carbon capture module includes a CCUS regeneration tower, an amine liquid cooler, a CCUS absorption tower, and an amine liquid preheater; The molten salt outlet and amine outlet of the heat exchange module are connected to the first inlet and the second inlet of the CCUS regeneration tower, respectively; the outlet of the CCUS regeneration tower is connected to the inlet of the amine cooler, the outlet of the amine cooler is connected to the top inlet of the CCUS absorption tower, the flue gas outlet of the waste heat boiler is connected to the bottom inlet of the CCUS absorption tower, the outlet of the CCUS absorption tower is connected to the inlet of the amine preheater, and the outlet of the amine preheater is connected to the amine inlet of the heat exchange module.

[0010] In one embodiment, the control unit is connected to the thermal power load signal, the molten salt temperature signal of the molten salt thermal storage unit, the amine temperature signal of the heat exchange module, and the amine liquid circulation carbon capture module.

[0011] This invention also provides a control method for a coupled system of molten salt thermal storage and carbon capture, comprising the following steps: Collect thermal power load data. When the thermal power load data is not less than the high load rated value, the three-way valve switches to the direct supply position, blocking the direct connection between the molten salt heat storage tank and the heat exchange module, and switching the connection between the waste heat boiler and the heat exchange module. The first molten salt circulation pump pumps the molten salt in the low temperature molten salt tank into the waste heat boiler, where it exchanges heat with the high temperature flue gas entering through the flue pipe to become high temperature molten salt. The high temperature molten salt flows into the heat exchange module and exchanges heat with the amine liquid introduced into the amine liquid circulation carbon capture module. The low temperature molten salt after heat exchange returns to the low temperature molten salt tank to complete the cycle. When the thermal power load data is less than the low load rated value, the three-way valve switches to the heat replenishment position. The three-way valve blocks the direct connection between the waste heat boiler and the heat exchange module, and switches the connection between the molten salt storage tank and the heat exchange module. The high-temperature molten salt in the molten salt storage tank is pressurized by the second molten salt circulation pump and enters the heat exchange module through the three-way valve to exchange heat with the amine liquid introduced into the amine liquid circulation carbon capture module. The low-temperature molten salt after heat exchange returns to the low-temperature molten salt tank to complete the cycle. When the thermal power load data is between the high load rating and the low load rating, the three-way valve dynamically switches between the direct supply position and the supplementary heat position to allocate the ratio of waste heat and stored heat, and maintain the temperature of the amine liquid.

[0012] In one embodiment, the amine liquid circulating carbon capture module includes a CCUS regeneration tower, an amine liquid cooler, a CCUS absorption tower, and an amine liquid preheater; It also includes an amine liquid adsorption-desorption cycle step: The CCUS regeneration tower outputs lean amine liquid, which is cooled by the amine liquid cooler and then sprayed at the top of the CCUS absorption tower. It comes into contact with the flue gas in the CCUS absorption tower to form rich amine liquid. The rich amine liquid flows into the amine liquid preheater, then enters the heat exchange module to exchange heat with high-temperature molten salt, and then enters the CCUS regeneration tower to repeat the above process for circulation.

[0013] In one embodiment, the thermal power load data is thermal power output, the high load rating is 80%, and the low load rating is 50%.

[0014] In one embodiment, the temperature fluctuation of the amine solution is ≤±2℃.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes a coupled system for molten salt thermal storage and carbon capture, which switches between "direct waste heat supply" and "storage-based heat supplementation" via a three-way reversing valve, eliminating the need for backup heat exchange equipment. In high-load mode, the three-way reversing valve switches to "direct waste heat boiler supply," where molten salt heated by high-temperature flue gas is directly fed into the heat exchange module to power the regeneration of the CCUS amine solution. Excess molten salt is stored in a molten salt tank, and the low-temperature waste heat from CCUS regeneration is used to preheat the amine solution, improving absorption efficiency. In low-load mode, the three-way reversing valve switches to "molten salt tank supplementation," where a molten salt circulation pump sends the high-temperature molten salt stored in the tank into the heat exchange module to maintain a stable amine regeneration temperature. Under these conditions, the CCUS operates at 60-70% of its rated load, preventing shutdowns due to insufficient heat source. The entire system and its operation control method effectively improve carbon capture efficiency and reduce system energy consumption. This invention solves the problems of poor load adaptability and low waste heat utilization in traditional CCUS systems. It is particularly suitable for small and medium-sized thermal power units.

[0016] Furthermore, in the flue gas process, the flue gas discharged from the unit enters the waste heat boiler to exchange heat with low-temperature molten salt, thus cooling the flue gas. This process makes full use of the waste heat of the flue gas that might otherwise be wasted. At the same time, in the desorption stage of the amine liquid process, the rich amine liquid first exchanges heat with the branch flue gas in the amine liquid preheater to raise its temperature, and then enters the integrated heat exchange module to exchange heat with the molten salt, realizing the cascade utilization of waste heat and improving the overall energy utilization efficiency.

[0017] Furthermore, the molten salt process forms a complete closed loop of heat absorption, storage, and release. During the heat absorption stage, the low-temperature molten salt can absorb heat from the flue gas in the waste heat boiler, be heated, and then stored in a high-temperature molten salt tank. During the heat release stage, the high-temperature molten salt releases heat in the integrated heat exchange module; after its temperature decreases, some of it returns to the low-temperature molten salt tank for temporary storage, awaiting the next heat absorption. This closed-loop design allows for flexible allocation of heat according to system needs, avoiding unnecessary energy loss, and enabling switching between "direct waste heat supply" and "storage-based heat supplementation." Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the coupled system of molten salt thermal storage and carbon capture of the present invention; Wherein: 1-Low-temperature molten salt tank; 2-First molten salt circulation pump; 3-Waste heat boiler; 4-Exhaust flue; 5-Second molten salt circulation pump; 6-Molten salt heat storage tank; 7-Three-way valve; 8-Heat exchange module; 9-CCUS regeneration tower; 10-Amine liquid cooler; 11-CCUS absorption tower; 12-Amine liquid preheater. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1This embodiment provides a coupled system and control method for synergistic molten salt thermal storage and carbon capture. The purpose of this embodiment is to solve the existing coupling architecture of molten salt thermal storage and carbon capture system (CCUS) in generating units, reduce the number of devices, lower the footprint and cost; achieve dynamic matching of CCUS heat sources under fluctuating thermal power loads to avoid large fluctuations in capture rate; improve waste heat utilization rate; and reduce the energy consumption per unit of CCUS capture.

[0022] Appendix Figure 1 This is a system illustration of the present invention, combined with... Figure 1 Further details.

[0023] A coupled system for synergistic molten salt thermal storage and carbon capture mainly includes core components: a molten salt thermal storage unit, an integrated heat exchange module 8, and an intelligent control unit. The molten salt thermal storage unit is a vertical cylindrical molten salt tank, divided into a high-temperature tank (molten salt thermal storage tank 6) and a low-temperature tank (low-temperature molten salt tank 1), (its volume is designed to meet the requirements of 4 hours of CCUS heating under low-load thermal power). It contains binary molten salt (sodium nitrate-potassium nitrate = 60:40, operating temperature 290-565℃), with a molten salt circulation pump at the top and a temperature sensor at the bottom. The integrated heat exchange module 8 integrates a set of shell-and-tube heat exchangers (molten salt flows through the shell side, and CCUS amine liquid flows through the tube side). A three-way reversing valve, i.e., a three-way valve 7, is installed at the heat exchanger inlet (one end connects to the waste heat boiler 3 of the thermal power plant, and the other end connects to the outlet of the molten salt tank (molten salt thermal storage tank 6)). A pressure sensor is installed at the outlet. Intelligent control unit: Based on PLC controller, it receives thermal power load signal, molten salt temperature signal and amine liquid temperature signal, and has a built-in load-heat matching algorithm.

[0024] The aforementioned coupled system for synergistic molten salt thermal storage and carbon capture specifically includes: a cryogenic molten salt tank 1, a first molten salt circulation pump 2, a waste heat boiler 3, a flue gas duct 4, a second molten salt circulation pump 5, a molten salt thermal storage tank 6, a three-way valve 7, a heat exchange module 8, a CCUS regeneration tower 9, an amine liquid cooler 10, a CCUS absorption tower 11, and an amine liquid preheater 12.

[0025] The molten salt storage unit consists of a low-temperature molten salt tank 1, a first molten salt circulation pump 2, a waste heat boiler 3, a second molten salt circulation pump 5, and a molten salt heat storage tank 6.

[0026] The heat exchange module 8 integrates a set of shell-and-tube heat exchangers. The shell side of the shell-and-tube heat exchangers is connected to the molten salt thermal storage unit, and the tube side is connected to the amine liquid circulation carbon capture module. A three-way valve 7 is installed at the molten salt inlet of the heat exchange module 8 to control the flow direction of the molten salt.

[0027] Among them, the CCUS regeneration tower 9, the amine liquid cooler 10, the CCUS absorption tower 11, and the amine liquid preheater 12 constitute the amine liquid circulation carbon capture module.

[0028] The flue gas inlet of the waste heat boiler 3 is connected to the exhaust pipe 4. The molten salt inlet of the waste heat boiler 3 is connected to the outlet of the low-temperature molten salt tank 1 via the first molten salt circulation pump 2. The molten salt outlet of the waste heat boiler 3 is connected to the inlet of the molten salt heat storage tank 6 and the three-way valve 7. The outlet of the molten salt heat storage tank 6 is connected to the three-way valve 7 via the second molten salt circulation pump 5. The molten salt outlet of the heat exchange module 8 is connected to the inlet of the low-temperature molten salt tank 1 and the first inlet of the CCUS regeneration tower 9. The amine liquid outlet of the heat exchange module 8 is connected to the second inlet of the CCUS regeneration tower 9. The outlet of the CCUS regeneration tower 9 is connected to the inlet of the amine liquid cooler 10. The outlet of the amine liquid cooler 10 is connected to the top inlet of the CCUS absorption tower 11. The flue gas outlet of the waste heat boiler 3 is connected to the bottom inlet of the CCUS absorption tower 11. The outlet of the CCUS absorption tower 11 is connected to the inlet of the amine liquid preheater 12. The outlet of the amine liquid preheater 12 is connected to the amine liquid inlet of the heat exchange module 8.

[0029] The waste heat boiler 3 has a flue gas inlet, a flue gas outlet, a molten salt inlet, and a molten salt outlet. The flue gas inlet of the waste heat boiler 3 is connected to the exhaust pipe 4 to introduce flue gas; the molten salt inlet of the waste heat boiler 3 is connected to the outlet of the low-temperature molten salt tank 1 via the first molten salt circulation pump 2, thereby enabling low-temperature molten salt to enter the waste heat boiler 3 from the low-temperature molten salt tank 1; the molten salt outlet of the waste heat boiler 3 is connected to the inlet of the molten salt heat storage tank 6 and a three-way valve 7.

[0030] The molten salt heat storage tank 6 is provided with an inlet and an outlet. The inlet of the molten salt heat storage tank 6 is connected to the molten salt outlet of the waste heat boiler 3. The outlet is connected to the three-way valve 7 via the second molten salt circulation pump 5, so that the molten salt in the molten salt heat storage tank 6 can be transported to the three-way valve 7 through the second molten salt circulation pump 5.

[0031] The heat exchange module 8 has a molten salt outlet, a molten salt inlet, an amine liquid outlet, and an amine liquid inlet. The molten salt outlet of the heat exchange module 8 is connected to the inlet of the cryogenic molten salt tank 1, used to return the molten salt after heat exchange to the cryogenic molten salt tank 1. Simultaneously, the molten salt outlet of the heat exchange module 8 is also connected to the first inlet of the CCUS regeneration tower 9, and the amine liquid outlet is connected to the second inlet of the CCUS regeneration tower 9, enabling the molten salt and amine liquid to enter the CCUS regeneration tower 9. The amine liquid inlet of the heat exchange module 8 is connected to the outlet of the amine liquid preheater 12.

[0032] The outlet of CCUS regeneration tower 9 is connected to the inlet of amine cooler 10. The material processed by CCUS regeneration tower 9 enters amine cooler 10 for cooling. The outlet of amine cooler 10 is connected to the top inlet of CCUS absorption tower 11. The cooled material enters CCUS absorption tower 11. The flue gas outlet of waste heat boiler 3 is connected to the bottom inlet of CCUS absorption tower 11, introducing the flue gas discharged from waste heat boiler 3 into CCUS absorption tower 11.

[0033] The outlet of CCUS absorber 11 is connected to the inlet of amine preheater 12. The material treated by CCUS absorber 11 enters amine preheater 12 for preheating. The outlet of amine preheater 12 is connected to the amine inlet of heat exchange module 8. The preheated amine returns to heat exchange module 8, forming a complete circulation system.

[0034] Furthermore, a pressure sensor is installed at the molten salt outlet of the heat exchange module 8; a temperature sensor is installed at the bottom of the molten salt heat storage tank 6; and the control unit is connected to the thermal power load signal, the molten salt temperature signal of the molten salt heat storage unit, the amine temperature signal of the heat exchange module 8, and the amine liquid circulation carbon capture module.

[0035] The flue gas process, molten salt process (endothermic-endothermic-exothermic closed loop), amine liquid process (adsorption-desorption cycle), and CO2 and clean flue gas process in the coupled system of molten salt thermal storage and carbon capture provided in this embodiment are as follows.

[0036] The flue gas flow process is as follows: The exhaust gas from the unit enters the waste heat boiler 3 through the exhaust pipe 4. In the waste heat boiler, the exhaust gas exchanges heat with low-temperature molten salt, and the exhaust gas is cooled to 50-60℃. The cooled exhaust gas then enters the CCUS absorption tower 11 (adapted to the amine liquid adsorption temperature to adsorb CO2).

[0037] The molten salt process is as follows: Heat absorption stage: Low-temperature molten salt at 290℃ is stored in the low-temperature molten salt tank. The low-temperature molten salt is transported to the waste heat boiler 3 under the action of the first molten salt circulation pump 2. In the waste heat boiler 3, the low-temperature molten salt exchanges heat with the clean flue gas at 120-150℃. After absorbing the heat from the flue gas, the low-temperature molten salt is heated to 450-500℃ and then transported to the high-temperature molten salt heat storage tank 6 for storage.

[0038] Heat release stage: The high-temperature molten salt in the molten salt storage tank is drawn out and enters the shell side of the integrated heat exchange module 8 via the second molten salt circulation pump 5. In the shell side, the high-temperature molten salt releases heat, and the temperature drops to 300-350℃. The cooled molten salt flows in two paths: one path is transported to the CCUS regeneration tower 9, where the heat released by the molten salt heats the rich amine liquid to 120-140℃, causing the rich amine liquid to desorb CO2; the other path flows back to the low-temperature molten salt tank 1 for temporary storage, waiting for the next heat absorption cycle.

[0039] The amine solution process (adsorption-desorption cycle) is as follows: Adsorption stage: The CCUS regeneration tower 9 outputs lean amine liquid at a temperature of 120-140℃. The lean amine liquid first enters the amine liquid cooler 10, where it is cooled to 40-60℃. The cooled lean amine liquid is then transported to the top of the CCUS absorption tower 11 for spraying, where it comes into countercurrent contact with the 50-60℃ flue gas entering from the bottom of the CCUS absorption tower 11. During the contact process, the lean amine liquid adsorbs CO2 from the flue gas and transforms into rich amine liquid, which collects at the bottom of the CCUS absorption tower 11.

[0040] Desorption stage: The rich amine liquid at the bottom of CCUS absorption tower 11 is drawn out and first enters amine liquid preheater 12. In amine liquid preheater 12, the rich amine liquid exchanges heat with the flue gas of the branch at 50-60℃, and the temperature rises to 80-90℃. The heated rich amine liquid then enters the tube side of the integrated heat exchange module 8 and exchanges heat with molten salt, and the temperature rises to 120-140℃. Subsequently, the rich amine liquid enters CCUS regeneration tower 9, where CO2 is desorbed and it becomes lean amine liquid again. Finally, the lean amine liquid enters amine liquid cooler 10 to start a new adsorption-desorption cycle.

[0041] The CO2 and clean flue gas processes are as follows: CO2: The CO2 desorbed from CCUS regeneration tower 9 first enters the condenser (for dehydration) to remove any moisture it contains. The dehydrated CO2 is then pressurized and transported to the storage system for geological storage or chemical utilization, depending on actual needs.

[0042] Clean flue gas: After decarbonization treatment in CCUS absorption tower 11, the clean flue gas enters amine liquid preheater 12. In amine liquid preheater 12, the clean flue gas transfers heat to the rich amine liquid, preheating it. The clean flue gas after preheating the rich amine liquid is discharged into the atmosphere through a chimney.

[0043] This embodiment provides a control method for a coupled system of molten salt thermal storage and carbon capture, which has dual-mode operation and includes the following steps: High-load mode (thermal power ≥ 80% of rated value): The three-way reversing valve is switched to "direct supply from waste heat boiler". The high-temperature flue gas (380-420℃) heats the molten salt and then sends it directly into the heat exchange module to provide energy for the regeneration of CCUS amine liquid (maintaining 120-150℃). Excess molten salt is sent to the molten salt tank for storage. At the same time, the low-temperature waste heat (80-100℃) after CCUS regeneration is used to preheat the amine liquid to improve the absorption efficiency. Low load mode (thermal power < 50% of rated value): The three-way reversing valve is switched to "molten salt tank supplementary heating". The molten salt circulation pump sends the high-temperature molten salt (≥450℃) stored in the tank to the heat exchange module to maintain the amine liquid regeneration temperature. At this time, CCUS operates at 60-70% of the rated load to avoid shutdown due to insufficient heat source.

[0044] In the above dynamic temperature control strategy, the intelligent control unit achieves precise heat matching through the following steps: real-time acquisition of thermal power load data; if the load is ≥80%, a high-load mode is triggered, controlling the opening of the three-way reversing valve (prioritizing direct supply, storing excess heat in salt) to stabilize the amine liquid temperature at 140-150℃ (capture rate ≥90%); if the load is <50%, a low-load mode is triggered, controlling the flow rate of the molten salt circulation pump (adjusted according to "amine liquid temperature 120-130℃") to avoid excessive heat release from the molten salt; if the load is between 50% and 80%, a "direct supply + supplementary heat" mixed mode is adopted, dynamically distributing the ratio of waste heat to stored heat through the three-way reversing valve to ensure that the amine liquid temperature fluctuation is ≤±2℃.

[0045] Specifically, the control methods described above are as follows: Collect thermal power load data. When the thermal power load data is not less than the high load rated value, the three-way valve 7 switches to the direct supply position, blocking the direct connection between the molten salt heat storage tank 6 and the heat exchange module 8, and switching the connection between the waste heat boiler 3 and the heat exchange module 8. The first molten salt circulation pump 2 pumps the molten salt in the low temperature molten salt tank 1 into the waste heat boiler 3, where it exchanges heat with the high temperature flue gas entering through the flue gas pipe 4 to become high temperature molten salt. The high temperature molten salt flows into the heat exchange module 8 and exchanges heat with the amine liquid introduced into the amine liquid circulation carbon capture module. The low temperature molten salt after heat exchange returns to the low temperature molten salt tank 1 to complete the cycle. When the thermal power load data is less than the low load rated value, the three-way valve 7 switches to the heat replenishment position. The three-way valve 7 blocks the direct connection between the waste heat boiler 3 and the heat exchange module 8, and switches the connection between the molten salt storage tank 6 and the heat exchange module 8. The high-temperature molten salt in the molten salt storage tank 6 is pressurized by the second molten salt circulation pump 5 and enters the heat exchange module 8 through the three-way valve 7 to exchange heat with the amine liquid introduced into the amine liquid circulation carbon capture module. The low-temperature molten salt after heat exchange returns to the low-temperature molten salt tank 1 to complete the cycle. When the thermal power load data is between the high load rating and the low load rating, the three-way valve 7 dynamically switches between the direct supply position and the supplementary heat position to allocate the ratio of waste heat and stored heat, and maintain the temperature of the amine liquid.

[0046] In summary, the coupled system of molten salt thermal storage and carbon capture provided in this embodiment simplifies the overall architecture. Compared with traditional multi-module coupled systems, it reduces two heat exchangers and one backup thermal storage tank, resulting in a 40% reduction in equipment quantity, a 15-20% reduction in floor space, and a 25% reduction in construction costs. Load adaptability is improved; through dual-mode switching, the CCUS system's tolerance to load fluctuations is enhanced, the capture rate is stabilized, and low-load shutdowns are avoided. Integrated heat exchange and cascaded utilization of waste heat significantly reduce the energy consumption per unit of CO2 capture in CCUS and improve waste heat utilization.

[0047] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A coupled system for synergistic molten salt thermal storage and carbon capture, characterized in that, The system includes a molten salt thermal storage unit, a heat exchange module (8), a flue gas duct (4), an amine liquid circulation carbon capture module, and a control unit; the control unit is connected to the molten salt thermal storage unit, the heat exchange module (8), and the amine liquid circulation carbon capture module; the heat exchange module (8) integrates a set of shell-and-tube heat exchangers, the shell side of which is connected to the molten salt thermal storage unit, and the tube side is connected to the amine liquid circulation carbon capture module; the molten salt thermal storage unit includes a low-temperature molten salt tank (1), a first molten salt circulation pump (2), a waste heat boiler (3), a second molten salt circulation pump (5), and a molten salt thermal storage tank (6); the heat exchange module... (8) The molten salt inlet is equipped with a three-way valve (7), which is used to control the flow direction of the molten salt; the flue gas inlet of the waste heat boiler (3) is connected to the flue gas pipe (4); the molten salt inlet of the waste heat boiler (3) is connected to the outlet of the low temperature molten salt tank (1) via the first molten salt circulation pump (2); the molten salt outlet of the waste heat boiler (3) is connected to the inlet of the molten salt heat storage tank (6) and the three-way valve (7); the outlet of the molten salt heat storage tank (6) is connected to the three-way valve (7) via the second molten salt circulation pump (5); the molten salt outlet of the heat exchange module (8) is connected to the inlet of the low temperature molten salt tank (1).

2. The coupled system for synergistic molten salt thermal storage and carbon capture according to claim 1, characterized in that, A pressure sensor is provided at the molten salt outlet of the heat exchange module (8).

3. The coupled system for synergistic molten salt thermal storage and carbon capture according to claim 1, characterized in that, A temperature sensor is installed at the bottom of the molten salt thermal storage tank (6).

4. The coupled system for synergistic molten salt thermal storage and carbon capture according to claim 1, characterized in that, The flue gas outlet of the waste heat boiler (3) is connected to the amine liquid circulating carbon capture module; the molten salt outlet of the heat exchange module (8) is connected to the amine liquid circulating carbon capture module.

5. The coupled system for synergistic molten salt thermal storage and carbon capture according to claim 1, characterized in that, The amine liquid circulating carbon capture module includes a CCUS regeneration tower (9), an amine liquid cooler (10), a CCUS absorption tower (11), and an amine liquid preheater (12). The molten salt outlet and amine outlet of the heat exchange module (8) are respectively connected to the first inlet and the second inlet of the CCUS regeneration tower (9); the outlet of the CCUS regeneration tower (9) is connected to the inlet of the amine cooler (10), the outlet of the amine cooler (10) is connected to the top inlet of the CCUS absorption tower (11), the flue gas outlet of the waste heat boiler (3) is connected to the bottom inlet of the CCUS absorption tower (11), the outlet of the CCUS absorption tower (11) is connected to the inlet of the amine preheater (12), and the outlet of the amine preheater (12) is connected to the amine inlet of the heat exchange module (8).

6. The coupled system for synergistic molten salt thermal storage and carbon capture according to claim 1, characterized in that, The control unit is connected to the thermal power load signal, the molten salt temperature signal of the molten salt thermal storage unit, the amine temperature signal of the heat exchange module (8), and the amine liquid circulation carbon capture module, respectively.

7. The control method for the coupled system of molten salt thermal storage and carbon capture as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Collect thermal power load data. When the thermal power load data is not less than the high load rated value, the three-way valve (7) switches to the direct supply position, blocks the direct connection between the molten salt heat storage tank (6) and the heat exchange module (8), and switches the connection between the waste heat boiler (3) and the heat exchange module (8). The first molten salt circulation pump (2) pumps the molten salt in the low temperature molten salt tank (1) into the waste heat boiler (3), and exchanges heat with the high temperature flue gas entering through the flue pipe (4) to become high temperature molten salt. The high temperature molten salt flows into the heat exchange module (8) and exchanges heat with the amine liquid introduced by the amine liquid circulation carbon capture module. The low temperature molten salt after heat exchange returns to the low temperature molten salt tank (1) to complete the cycle. When the thermal power load data is less than the low load rated value, the three-way valve (7) switches to the heat replenishment position. The three-way valve (7) blocks the direct connection between the waste heat boiler (3) and the heat exchange module (8), and switches the connection between the molten salt storage tank (6) and the heat exchange module (8). The high-temperature molten salt in the molten salt storage tank (6) is pressurized by the second molten salt circulation pump (5) and enters the heat exchange module (8) through the three-way valve (7) to exchange heat with the amine liquid introduced by the amine liquid circulation carbon capture module. The low-temperature molten salt after heat exchange returns to the low-temperature molten salt tank (1) to complete the cycle. When the thermal power load data is between the high load rating and the low load rating, the three-way valve (7) dynamically switches the direct supply position and the supplementary heat position to allocate the ratio of residual heat and heat storage, and maintain the temperature of the amine liquid.

8. The control method for the coupled system of molten salt thermal storage and carbon capture according to claim 7, characterized in that, The amine liquid circulating carbon capture module includes a CCUS regeneration tower (9), an amine liquid cooler (10), a CCUS absorption tower (11), and an amine liquid preheater (12). It also includes an amine liquid adsorption-desorption cycle step: The CCUS regeneration tower (9) outputs lean amine liquid. After being cooled by the amine liquid cooler (10), the lean amine liquid enters the top of the CCUS absorption tower (11) for spraying. It comes into contact with the flue gas in the CCUS absorption tower (11) to form rich amine liquid. The rich amine liquid flows into the amine liquid preheater (12), and then enters the heat exchange module (8) to exchange heat with the high-temperature molten salt. It then enters the CCUS regeneration tower (9) to repeat the above process and circulate.

9. The control method for the coupled system of molten salt thermal storage and carbon capture according to claim 7, characterized in that, The thermal power load data refers to thermal power output, with the high load rating at 80% and the low load rating at 50%.

10. The control method for the coupled system of molten salt thermal storage and carbon capture according to claim 7, characterized in that, The temperature fluctuation of the amine solution is ≤±2℃.

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