Temperature and pressure regulation system and method for a supercritical carbon dioxide cycle system

Abstract

The application discloses a temperature and pressure regulating system and method of a supercritical carbon dioxide circulation system, which is composed of a storage tank, a booster pump, a water bath gasifier, a pressure isolation tank, a pressure stabilizing tank, a pneumatic pressure regulating valve, a three-way regulating valve and a pneumatic pressure reducing valve, and temperature and pressure sensors are arranged on the tank body of the pressure isolation tank and the outlet of the pressure stabilizing tank; the tank body temperature sensor of the pressure isolation tank is connected with the water bath gasifier in a linkage manner to control the temperature of the carbon dioxide entering the pressure isolation tank; the tank body pressure sensor of the pressure isolation tank is connected with the motor of the booster pump in a linkage manner to control the pressure of the carbon dioxide entering the pressure isolation tank; the pressure stabilizing tank adopts a parallel type and is provided with an electric heating band on one of the tank bodies; the outlet temperature sensor of the pressure stabilizing tank is connected with the three-way regulating valve in a linkage manner to control the temperature of the carbon dioxide entering the supercritical carbon dioxide circulation system by adjusting the flow ratio; the outlet pressure sensor of the pressure stabilizing tank is connected with the pneumatic regulating valve of the pressure isolation tank and the pressure reducing valve on the carbon dioxide storage tank in a linkage manner to coordinate the control of the pressure of the carbon dioxide entering the supercritical carbon dioxide circulation system. The system as a whole adopts a PID algorithm for linkage control, and the temperature and pressure of the entering carbon dioxide can be accurately controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of supercritical carbon dioxide cycle power and power generation, in particular to a temperature and pressure regulation system and method of a supercritical carbon dioxide cycle system. BACKGROUND

[0002] With the proposal of the "carbon peak" and "carbon neutralization" targets, finding clean and efficient energy utilization methods has been the focus of domestic and foreign scholars. Carbon dioxide is non-toxic, easy to capture, and easy to reach supercritical state. The critical point of carbon dioxide is 30.98℃, 7.38MPa. Carbon dioxide has excellent thermophysical properties in the near-critical region, such as high density, high specific heat capacity, and low compression power consumption. Supercritical carbon dioxide (S-CO2) as a working medium applied to power systems simplifies the system structure, reduces the power consumption of the compressor, has wide heat source matching (200℃-850℃), low power viscosity coefficient, and reduces the resistance of the working medium during system operation, further improving system efficiency. Supercritical carbon dioxide Brayton cycle can combine coal-fired, nuclear, wind, solar and other energy as a secondary circuit power generation system, and can also be used as a power system for mobile platforms such as ships and underwater submarines, and has a wide market prospect and application value. S-CO2 Brayton cycle is a closed cycle system, and the working medium at the inlet of the compressor is in the pseudo-critical region. The high nonlinearity of S-CO2 thermophysical properties in the pseudo-critical region, the strong coupling of parameters between closed system equipment, and other factors make the system design and control extremely difficult. Reducing the fluctuation amplitude of the system pressure and improving the stability of the operation become key problems.

[0003] CN202111422045 is a supercritical carbon dioxide cycle working medium replacement and pressure charging system and method. This system only considers the pressure regulation of the first charging, and cannot realize the dynamic stability control of temperature and pressure during system operation. CN202011308876 describes a supercritical carbon dioxide closed cycle temperature and pressure coupling control system. This control system can only realize single control of the increase of carbon dioxide pressure at the inlet of the compressor, cannot realize bidirectional control of pressure reduction and pressure increase, and the temperature at the inlet of the compressor is controlled by mixing the heated carbon dioxide with the original carbon dioxide in the closed cycle, which cannot realize the rapid increase of the temperature of carbon dioxide entering the compressor in a short time, does not have the function of reducing the temperature of carbon dioxide at the inlet of the compressor, and has a slow control response rate.

[0004] In order to ensure the stability of the equipment during system operation, prevent the gas-liquid two-phase impact caused by carbon dioxide trans-critical, and reduce the influence of pressure fluctuation on downstream equipment and devices, it is urgent to develop a mature and flexible temperature and pressure control system and method. SUMMARY

[0005] In response to the problems existing in the prior art, the present invention provides a temperature and pressure control system and method for a supercritical carbon dioxide circulation system. The system accurately controls the temperature and pressure of the supercritical carbon dioxide circulation system, greatly reducing the temperature and pressure fluctuations during the operation of the carbon dioxide Brayton power system.

[0006] The present invention is achieved through the following technical solutions:

[0007] A temperature and pressure control system for a supercritical carbon dioxide circulation system includes a carbon dioxide storage tank, the outlet of which is sequentially connected to a booster pump, a water bath vaporizer, and a pressure isolation tank. The outlet of the pressure isolation tank is connected to the supercritical carbon dioxide circulation system via a pressure regulating device. The circulation loop of the supercritical carbon dioxide circulation system is connected to the inlet of the pressure regulating device. The pressure of the pressure isolation tank is greater than the pressure of the supercritical carbon dioxide circulation system.

[0008] The pressure regulating device includes multiple pressure tanks connected in parallel, and a heating device is provided on at least one pressure tank. The input ends of the multiple pressure tanks are connected to the pressure regulating pipeline. The output ends of the multiple pressure tanks are connected to the supercritical carbon dioxide circulation system through a regulating valve after converging. The carbon dioxide temperature in the supercritical carbon dioxide circulation system is adjusted according to the circulation ratio of the multiple pressure tanks. The pressure relief end of the pressure regulating device is connected to the inlet of the carbon dioxide storage tank through a pressure relief pipeline.

[0009] Preferably, the carbon dioxide storage tank is provided with a pneumatic pressure relief valve, a safety valve, a pressure sensor and a temperature sensor. The pressure sensor is interlocked with the pneumatic pressure relief valve, and the pneumatic pressure relief valve is used to control the pressure of the carbon dioxide storage tank.

[0010] Preferably, a safety valve, a temperature sensor and a pressure sensor are provided on the pressure isolation tank. The temperature sensor is interlocked with the water bath vaporizer to control the temperature of the carbon dioxide in the pressure isolation tank. The pressure sensor is interlocked with the booster pump to control the pressure of the pressure isolation tank.

[0011] Preferably, a first pneumatic regulating valve is provided at the outlet of the pressure isolation tank, a pressure sensor is provided on the pipeline between the regulating valve and the supercritical carbon dioxide circulation system, a second pneumatic pressure reducing valve is provided on the pressure relief pipeline, and the pressure sensor is interlocked with the first pneumatic regulating valve and the second pneumatic pressure reducing valve;

[0012] When the pressure of the supercritical carbon dioxide circulation system is lower than the preset value, the second pneumatic pressure reducing valve is closed, the first pneumatic regulating valve is opened, and the supercritical carbon dioxide circulation system is pressurized through the pressure isolation tank;

[0013] When the pressure of the supercritical carbon dioxide circulation system is higher than a preset value, the second pneumatic pressure reducing valve is opened, the first pneumatic regulating valve is closed, and the pressure of the supercritical carbon dioxide circulation system is reduced by the pressure regulating device.

[0014] Preferably, a temperature sensor is provided on the pressure isolation tank, and the temperature sensor is interlocked with the water bath gasifier to control the temperature of the carbon dioxide in the pressure isolation tank.

[0015] Preferably, a stop valve and a carbon dioxide filter are provided on the pipeline between the carbon dioxide storage tank and the booster pump.

[0016] Preferably, a safety valve, a one-way valve and a stop valve are provided on the pipeline between the booster pump and the water bath vaporizer.

[0017] A method for controlling the temperature and pressure of a supercritical carbon dioxide circulation system.

[0018] When the pressure of the supercritical carbon dioxide circulation system is lower than the preset pressure, the pressure isolation tank pressurizes the supercritical carbon dioxide circulation system through the pressure regulating device;

[0019] When the pressure of the supercritical carbon dioxide circulation system is higher than the preset pressure, the supercritical carbon dioxide circulation system is depressurized through the pressure relief pipeline of the pressure regulating device;

[0020] When the temperature of carbon dioxide in the supercritical carbon dioxide circulation system exceeds a preset temperature, the circulation ratio of multiple pressure tanks is controlled to adjust the temperature of carbon dioxide in the supercritical carbon dioxide circulation system.

[0021] Preferably, when the pressure of the pressure isolation tank is lower than the preset pressure, the pressure isolation tank is pressurized by a booster pump;

[0022] When the pressure in the pressure isolation tank is greater than the preset pressure, the pressure is reduced through the safety valve of the pressure isolation tank.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] The present invention provides an automatic temperature and pressure control system for a supercritical carbon dioxide circulation system, comprising a carbon dioxide storage tank, a booster pump, a water bath vaporizer, a pressure isolation tank, and a pressure regulating device. The pressure isolation tank is connected to the supercritical carbon dioxide circulation system via the pressure regulating device. The water bath vaporizer stores heated carbon dioxide in the pressure isolation tank, thereby achieving primary control of the carbon dioxide temperature and pressure and directly outputting the carbon dioxide to the supercritical carbon dioxide circulation system via the pressure regulating device. A plurality of parallel pressure tanks are used to perform secondary control of the carbon dioxide temperature and pressure, thereby achieving temperature and pressure control of the supercritical carbon dioxide circulation system. Simultaneously, a pressure relief pipeline is used to reduce the pressure of the supercritical carbon dioxide circulation system. The provision of the pressure isolation tank avoids the pressure inertia of the booster pump. The provision of the pressure regulating valve can quickly and accurately adjust the pressure in the downstream pressure regulating tank, thereby significantly improving the stability of the system pressure. The temperature and pressure control range is wide and is not limited to a single control point. The interlocking control of multiple valves, electric heating cables, and the booster pump increases the control range of the system target value. Furthermore, after the supercritical carbon dioxide circulation system is depressurized, excess carbon dioxide is returned to the storage tank for secondary use after the pressure is reduced, thereby effectively reducing operating costs.

[0025] Furthermore, a linkage mechanism is employed to achieve dynamic temperature and pressure control. Control target values ​​can be changed while the supercritical carbon dioxide circulation system is operating, enabling the system's temperature and pressure to be altered without shutting down the system. Furthermore, the system responds quickly, and temperature control using a three-way regulating valve to adjust the flow distribution ratio effectively reduces system thermal inertia and significantly increases the temperature regulation rate. The control process is simple and highly reliable. The underlying logic of the pressure and temperature control method utilizes a PID algorithm, eliminating the need to develop complex control strategies and algorithms to achieve precise temperature and pressure control of the supercritical carbon dioxide circulation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the temperature and pressure automatic control system of the supercritical carbon dioxide circulation system of the present invention;

[0027] In the figure: 1. Carbon dioxide storage tank; 2. Pneumatic pressure relief valve; 3. Safety valve; 4. Stop valve; 5. Carbon dioxide filter; 6. Carbon dioxide booster pump; 7. Safety valve; 8. Check valve; 9. Stop valve; 10. Water bath vaporizer; 11. Stop valve; 12. Pressure isolation tank; 13. Safety valve; 14. Pneumatic regulating valve; 15. One-way valve; 16. Pressure regulating tank; 17. Electric heating tape; 18. Safety valve; 19 Safety valve; 20 Three-way regulating valve; 21 Pneumatic pressure reducing valve; 22 Supercritical carbon dioxide circulation system. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below with reference to the accompanying drawings, which are intended to explain rather than limit the present invention.

[0029] like Figure 1 As shown, a temperature and pressure control system of a supercritical carbon dioxide circulation system includes a carbon dioxide storage tank 1, a booster pump 6, a water bath vaporizer 10, a pressure isolation tank 12 and a pressure stabilizing tank 16.

[0030] The carbon dioxide storage tank 1 is connected to the booster pump 6, the water bath vaporizer 10, and the pressure isolation tank 12 in sequence through a first pipeline. The outlet of the pressure isolation tank 12 is provided with a first pipeline and a second pipeline. The pressure isolation tank 12 is connected to the supercritical carbon dioxide circulation system 22 through the first pipeline. The second pipeline is connected to the supercritical carbon dioxide circulation system 22 through a pressure stabilizing tank 16. The inlet of the pressure stabilizing tank 16 is connected to the carbon dioxide storage tank 1 through a third pipeline. A pneumatic pressure reducing valve 21 is provided on the third pipeline.

[0031] The CO2 storage tank 1 is equipped with a pneumatic pressure relief valve 2, a safety valve 3, a pressure sensor, and a temperature sensor. The pressure sensor is interlocked with the pneumatic pressure relief valve 2 to control the internal pressure of the CO2 storage tank 1. A shut-off valve 4 and a CO2 filter 5 are installed in the pipeline between the CO2 storage tank 1 and the booster pump 6 to filter impurities within the CO2 storage tank and prevent them from entering the supercritical CO2 circulation system and affecting its normal operation. When the CO2 storage tank pressure exceeds the target pressure, the pneumatic pressure relief valve is opened to release the CO2. When the CO2 storage tank pressure reaches the target value, the pneumatic pressure relief valve is closed. The safety valve is a mechanical spring that releases the CO2 if the pneumatic pressure relief valve 2 fails to operate.

[0032] A safety valve 7, a one-way valve 8 and a stop valve 9 are provided on the pipeline between the booster pump 6 and the water bath vaporizer 10. The safety valve can automatically exhaust and reduce the pressure when the pressure in the pipeline is too high; the one-way valve can prevent the reverse flow caused by the gasification and expansion of carbon dioxide in the water bath vaporizer, thereby protecting the booster pump body.

[0033] A stop valve 11 is provided on the pipeline between the water bath vaporizer 10 and the pressure isolation tank 12. The stop valve can manually adjust the maximum flow rate entering the pressure isolation tank. A safety valve 13, a temperature sensor and a pressure sensor are provided on the pressure isolation tank 12. The temperature sensor is interlocked with the water bath vaporizer 10 to control the temperature of the carbon dioxide in the pressure isolation tank 12. The pressure sensor is interlocked with the booster pump 6 to control the pressure of the pressure isolation tank 12.

[0034] The booster pump uses a variable-frequency motor with adjustable speed. By controlling the frequency of the variable-frequency motor, the flow and pressure of the carbon dioxide at the outlet of the booster pump can be regulated. The PID algorithm is used to interlock the variable-frequency motor of the booster pump and the pressure sensor on the pressure isolation tank. When the pressure of the pressure sensor on the pressure isolation tank is less than the target value, the booster pump starts to increase the pressure of the pressure isolation tank. When the pressure of the pressure sensor on the pressure isolation tank approaches the target value, the booster pump automatically slows down. When the pressure of the pressure sensor on the pressure isolation tank is equal to the target value, the booster pump stops. The interlocking of the pressure sensor on the pressure isolation tank and the booster pump can realize automatic and precise control of the pressure in the pressure isolation tank, and the target pressure value of the pressure isolation tank is higher than the target pressure value of the pressure stabilizing tank.

[0035] A pneumatic regulating valve 14 and a one-way valve 15 are installed on the pipeline between the pressure isolation tank 12 and the pressure stabilizing tank 16. A safety valve 18 and a safety valve 19 are installed on the pressure stabilizing tank 16. The pressure stabilizing tank 16 is in the form of a parallel double tank body. An electric heating tape 17 is provided on one of the tank bodies. The outlet of the pressure stabilizing tank 16 is connected to the inlet of the supercritical carbon dioxide circulation system 22 through a three-way regulating valve 20, and a temperature sensor and a pressure sensor are provided on the pipeline. The temperature sensor is interlocked with the three-way regulating valve 20, and the pressure sensor is interlocked with the pneumatic regulating valve 14 and the pneumatic pressure reducing valve 21.

[0036] A temperature sensor is set on the pressure isolation tank, and the temperature sensor is interlocked with the water bath vaporizer. When the temperature of the temperature sensor on the pressure isolation tank is lower than the target value, the water bath vaporizer increases the water bath temperature and increases the temperature of the carbon dioxide entering the pressure isolation tank. When the temperature of the temperature sensor on the pressure isolation tank is greater than or equal to the target value, the water bath vaporizer stops heating and reduces the temperature of the carbon dioxide entering the pressure isolation tank.

[0037] A pneumatic regulating valve 14 and a one-way valve are arranged on the first pipeline between the pressure isolation tank and the pressure-sustaining tank. The pneumatic regulating valve and the pressure sensor on the pipeline between the pressure-sustaining tank and the supercritical carbon dioxide circulation system are interlocked, and a PID algorithm is adopted. When the pressure of the pressure sensor on the pipeline between the pressure-sustaining tank and the supercritical carbon dioxide circulation system is less than the target value, the pneumatic regulating valve is opened appropriately to increase the carbon dioxide pressure of the pressure-sustaining tank. When the pressure of the pressure sensor on the pipeline between the pressure-sustaining tank and the supercritical carbon dioxide circulation system is close to the target value, the pneumatic regulating valve is closed appropriately. When the pressure of the pressure sensor on the pipeline between the pressure-sustaining tank and the supercritical carbon dioxide circulation system reaches the target value, the pneumatic regulating valve is closed; the one-way valve is used to prevent the carbon dioxide in the second pipeline connected between the pressure isolation tank and the pressure-sustaining tank and the supercritical carbon dioxide circulation system from flowing back and impacting the valve body of the pneumatic regulating valve.

[0038] A pneumatic pressure reducing valve 21 is provided on the third pipeline between the pressure stabilizing tank inlet and the carbon dioxide storage tank. The pneumatic pressure reducing valve and the pressure sensor on the pipeline between the pressure stabilizing tank and the supercritical carbon dioxide circulation system are interlockedly controlled. When the pressure of the pressure sensor on the pipeline between the pressure stabilizing tank and the supercritical carbon dioxide circulation system is greater than the target value, the pneumatic pressure reducing valve is opened appropriately to reduce the carbon dioxide pressure of the pressure stabilizing tank. When the pressure of the pressure sensor on the pipeline between the pressure stabilizing tank and the supercritical carbon dioxide circulation system is close to the target value, the pneumatic pressure reducing valve is closed appropriately. When the pressure of the pressure sensor on the pipeline between the pressure stabilizing tank and the supercritical carbon dioxide circulation system reaches the target value, the pneumatic pressure reducing valve is closed.

[0039] The pressure-surge tank adopts a horizontal type with two parallel tanks, and an electric heating tape is set on one of the tanks. The temperature of the carbon dioxide in a single tank of the pressure-surge tank is increased by controlling the heating temperature of the electric heating tape. The carbon dioxide temperature inside the two parallel pressure-surge tanks is different. The flow ratio of different tanks of the pressure-surge tank is adjusted by controlling the opening of the three-way regulating valve, and finally the temperature of the carbon dioxide flowing into the supercritical carbon dioxide circulation system is accurately controlled; all pipelines and equipment are subjected to thermal insulation treatment to reduce the impact of the environment on the present invention and improve the overall control accuracy.

[0040] All interlocking controls in the present invention are based on the PID (proportional, integral, differential control) algorithm, the basic principles of which are as follows:

[0041]

[0042] Where k p is the proportional magnification factor, k i is the integration coefficient, k d is the differential coefficient. In the real-time process of this scheme, k can be adjusted p 、k i 、k d Three coefficients to increase overall control accuracy;

[0043] The method of the temperature and pressure automatic control system of the supercritical carbon dioxide circulation system is as follows:

[0044] When the pressure of the supercritical carbon dioxide circulation system is lower than the preset pressure, the pressure isolation tank 12 pressurizes the supercritical carbon dioxide circulation system through the first pipeline;

[0045] When the pressure of the supercritical carbon dioxide circulation system is higher than the preset pressure, the carbon dioxide in the supercritical carbon dioxide circulation system is depressurized through the pressure relief pipeline of the pressure stabilizing tank;

[0046] When the temperature of carbon dioxide in the supercritical carbon dioxide circulation system exceeds a preset temperature, the circulation ratio of the pressure stabilizing tank is controlled to adjust the temperature of carbon dioxide in the supercritical carbon dioxide circulation system.

[0047] When the pressure of the pressure isolation tank 12 is lower than the preset pressure, the pressure isolation tank 12 is pressurized by the booster pump 6;

[0048] When the pressure of the pressure isolation tank 12 is greater than the preset pressure, the pressure is reduced through the safety valve of the pressure isolation tank 12 .

[0049] Example 1

[0050] The following describes in detail the method for using the temperature and pressure automatic control system provided by the present invention, taking the supercritical carbon dioxide Brayton cycle system as an example.

[0051] Before the temperature and pressure control system is put into operation for the first time, the air in the system pipes needs to be exhausted and the pipes need to be filled with high-purity carbon dioxide as follows:

[0052] First, turn on the power of the water bath vaporizer 10 and set the water bath temperature to 70°C to preheat the pipeline in the water bath vaporizer 10; then, use a vacuum pump to evacuate the system to a relative vacuum degree of -90 kPa, adjust the opening of the stop valve 9 to 10%, open the stop valve 4, and use the pressure difference between the carbon dioxide storage tank 1 and the vacuum pipeline to fill the pipeline with carbon dioxide. When the pressure of the pressure isolation tank 12 reaches the same level as that of the carbon dioxide storage tank 1, close the stop valve 4 and evacuate the carbon dioxide in the pipeline; finally, repeat the above steps to complete the secondary vacuuming and charging to improve the purity of the carbon dioxide in the pipeline. After completing the above steps, the temperature and pressure control system can be used normally;

[0053] In this example, the design pressure of carbon dioxide storage tank 1 is 2.5 MPa, and the actual operating pressure is 1.9 MPa. When the pressure feedback pressure of the pressure sensor exceeds 2.1 MPa, the pneumatic pressure relief valve 2 opens to relieve pressure. When the pressure feedback pressure of the pressure sensor is lower than 1.9 MPa, the pneumatic pressure relief valve 2 closes. The safety valve 3 adopts a mechanical spring type. When the pressure is greater than 2.4 MPa, the safety valve 3 automatically exhausts.

[0054] In this example, the temperature sensor of the pressure isolation tank 12 is connected to the water bath temperature of the water bath gasifier 10, the pressure sensor is connected to the motor frequency of the plunger pump 6, the temperature of the pressure isolation tank 12 is set to 40℃ and the pressure is 10 MPa, when the temperature of the pressure isolation tank 12 is less than 40℃, the water bath temperature of the water bath gasifier 10 is increased to increase the temperature of the carbon dioxide entering the pressure isolation tank 12, when the temperature of the pressure isolation tank 12 is greater than 40℃, the water bath gasifier 10 stops heating to reduce the temperature of the carbon dioxide entering the pressure isolation tank 12; when the pressure of the pressure isolation tank 12 is less than 10 MPa, the motor frequency of the plunger pump 6 is increased to increase the pressure of the pressure isolation tank 12, when the pressure of the pressure isolation tank 12 reaches 10 MPa, the motor frequency of the plunger pump 6 is reduced and eventually stopped to maintain the pressure of the pressure isolation tank 12 at 10 MPa;

[0055] In this example, by adjusting the opening degree of the stop valve 9 and the stop valve 11, the flow rate of carbon dioxide entering the water bath gasifier 10 and the pressure isolation tank 12 can be controlled;

[0056] In this example, the setting of the one-way valve 8 can prevent the reverse flow caused by the expansion of carbon dioxide in the water bath gasifier, protecting the pump body of the booster pump 6, and the setting of the one-way valve 15 can prevent the backflow of carbon dioxide in the second pipeline connecting the pressure isolation tank and the pressure stabilizing tank and the supercritical carbon dioxide circulation system from impacting the valve body of the pneumatic regulating valve;

[0057] In this example, the set pressure of the safety valve 3 is 2.4 MPa, and the set pressure of the safety valve 7, the safety valve 13, the safety valve 18 and the safety valve 19 is 12 MPa;

[0058] In this example, the pressure of the carbon dioxide entering the supercritical carbon dioxide Brayton cycle system can be controlled by adjusting the opening degree of the pneumatic regulating valve 14 and the pneumatic pressure reducing valve 21, the outlet pressure sensor of the pressure stabilizing tank 16 is connected to the pneumatic regulating valve 14 and the pneumatic pressure reducing valve 21, the target set value of the pressure of the carbon dioxide entering the supercritical carbon dioxide Brayton cycle system needs to be lower than or equal to the pressure in the pressure isolation tank 12, when the pressure in the pressure stabilizing tank 16 is lower than the target set value, the opening degree of the pneumatic regulating valve 14 is adjusted to control the pressure rising rate of the pressure stabilizing tank 16, and the maximum pressure of the pressure stabilizing tank 16 is equal to the pressure of the pressure isolation tank 12, when the pressure in the pressure stabilizing tank 16 is higher than the target set value, the pneumatic pressure reducing valve 21 is opened to exhaust and reduce the pressure, and the opening degree of the pneumatic pressure reducing valve 21 is adjusted to control the pressure reduction rate;

[0059] The outlet temperature sensor of the surge tank 16 is interlocked with the three-way regulating valve 20. The temperature in the supercritical carbon dioxide Brayton cycle system can be adjusted by changing the diversion ratio of the three-way regulating valve 20. The target value of the outlet temperature of the surge tank 16 is set to 38°C. An electric heating tape 17 is provided on one of the tank bodies of the parallel surge tanks 16. The working medium in the tank body is heated to 50°C by the electric heating tape 17. When the outlet temperature of the surge tank 16 is lower than 38°C, the flow ratio of the tank body provided with the electric heating tape 17 is increased to increase the temperature of the carbon dioxide entering the supercritical carbon dioxide circulation system 22. When the outlet temperature of the surge tank 16 is higher than 38°C, the flow ratio of the tank body provided with the electric heating tape 17 is reduced to reduce the temperature of the carbon dioxide entering the supercritical carbon dioxide circulation system 22, thereby achieving automatic adjustment of the temperature of the carbon dioxide entering the supercritical carbon dioxide circulation system 22.

[0060] More specifically, Figure 1 As shown, after the carbon dioxide circulation temperature and pressure control system completes the filling and discharge of carbon dioxide, the power supply of the water bath vaporizer 10 is started, the target temperature of the pressure isolation tank 12 is set to 40°C and the target pressure is 10MPa, the stop valve 4 is opened, and the stop valve 9 and the stop valve 11 are slowly opened. The system will automatically adjust the heating power and water bath temperature of the water bath vaporizer 10 according to the temperature of the temperature sensor on the pressure isolation tank 12, and automatically adjust the motor frequency of the booster pump 6 according to the pressure of the pressure sensor on the pressure isolation tank 12, thereby changing the carbon dioxide flow entering the pressure isolation tank 12, and finally controlling the boosting rate. When the pressure reaches 10MPa, the booster pump 6 slowly stops, and when the pressure is lower than 10MPa, the booster pump 6 automatically starts boosting; set the target pressure of the supercritical carbon dioxide circulation system 22 inlet to 7.8MPa and the target temperature to 38°C, and the system will automatically adjust the pressure at the outlet of the pressure stabilizing tank 16 to the inlet of the supercritical carbon dioxide circulation system 22. The force sensor automatically adjusts the pressure. When the pressure indication is lower than 7.8 MPa, the pneumatic regulating valve 14 opens to increase the tank pressure of the pressure-sustaining tank 16. When the pressure indication is higher than 7.8 MPa, the pneumatic reducing valve 21 on the third pipeline opens to reduce the tank pressure of the pressure-sustaining tank 16. When the pressure of the carbon dioxide storage tank 1 is higher than 2.1 MPa, the pneumatic pressure relief valve 2 opens to exhaust and relieve pressure. The system automatically adjusts the temperature according to the temperature sensor indication at the outlet of the pressure-sustaining tank 16 to the inlet of the supercritical carbon dioxide circulation system 22. When the temperature is lower than 38°C, the three-way regulating valve increases the carbon dioxide flow rate of the tank wrapped with the electric heating tape 17 and reduces the flow rate of the other tank to increase the temperature. When the temperature is higher than 38°C, the three-way regulating valve reduces the carbon dioxide flow rate of the tank wrapped with the electric heating tape 17 and increases the flow rate of the other tank to reduce the temperature. The above process realizes automatic control of the temperature and pressure of the carbon dioxide entering the supercritical carbon dioxide circulation system 22.

[0061] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A temperature and pressure control system for a supercritical carbon dioxide circulation system, characterized in that: The invention comprises a carbon dioxide storage tank (1), the outlet of which is connected in sequence to a booster pump (6), a water bath vaporizer (10) and a pressure isolation tank (12), the outlet of the pressure isolation tank (12) being connected to a supercritical carbon dioxide circulation system via a pressure regulating device, the circulation loop of the supercritical carbon dioxide circulation system being connected to the inlet of the pressure regulating device, and the pressure of the pressure isolation tank (12) being greater than the pressure of the supercritical carbon dioxide circulation system; The pressure regulating device comprises a plurality of pressure tanks connected in parallel, and at least one pressure tank is provided with a heating device, the input ends of the plurality of pressure tanks are connected to a pressure regulating pipeline, the output ends of the plurality of pressure tanks are connected to a supercritical carbon dioxide circulation system through a regulating valve after converging, the temperature of carbon dioxide in the supercritical carbon dioxide circulation system is regulated according to the circulation ratio of the plurality of pressure tanks, and the pressure relief end of the pressure regulating device is connected to the inlet of the carbon dioxide storage tank (1) through a pressure relief pipeline; The carbon dioxide storage tank (1) is provided with a pneumatic pressure relief valve (2), a safety valve (3), a pressure sensor and a temperature sensor. The pressure sensor is interlocked with the pneumatic pressure relief valve (2). The pneumatic pressure relief valve (2) is used to control the pressure of the carbon dioxide storage tank (1). The pressure isolation tank (12) is provided with a safety valve (13), a temperature sensor and a pressure sensor. The temperature sensor is interlocked with the water bath vaporizer (10) to control the temperature of the carbon dioxide in the pressure isolation tank (12). The pressure sensor is interlocked with the booster pump (6) to control the pressure of the pressure isolation tank (12). A first pneumatic regulating valve (14) is provided at the outlet of the pressure isolation tank (12); a pressure sensor is provided on the pipeline between the regulating valve and the supercritical carbon dioxide circulation system; a second pneumatic pressure reducing valve (21) is provided on the pressure relief pipeline; the pressure sensor is interlocked with the first pneumatic regulating valve (14) and the second pneumatic pressure reducing valve (21); When the pressure of the supercritical carbon dioxide circulation system is lower than a preset value, the second pneumatic pressure reducing valve (21) is closed, the first pneumatic regulating valve (14) is opened, and the supercritical carbon dioxide circulation system is pressurized through the pressure isolation tank (12); When the pressure of the supercritical carbon dioxide circulation system is higher than a preset value, the second pneumatic pressure reducing valve (21) is opened, the first pneumatic regulating valve (14) is closed, and the pressure of the supercritical carbon dioxide circulation system is reduced by the pressure regulating device; When the pressure of the pressure isolation tank (12) is lower than the preset pressure, the pressure isolation tank (12) is pressurized by the booster pump (6); When the pressure of the pressure isolation tank (12) is greater than the preset pressure, the pressure is reduced through the safety valve of the pressure isolation tank (12).

2. The temperature and pressure control system of a supercritical carbon dioxide circulation system according to claim 1, characterized in that: A stop valve (4) and a carbon dioxide filter (5) are provided on the pipeline between the carbon dioxide storage tank (1) and the booster pump (6).

3. The temperature and pressure control system of a supercritical carbon dioxide circulation system according to claim 1, characterized in that: A safety valve (7), a one-way valve (8) and a stop valve (9) are provided on the pipeline between the booster pump (6) and the water bath vaporizer (10).

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