A dense-phase carbon dioxide supply-storage system and its usage method

Abstract

The present invention discloses a dense-phase carbon dioxide supply-storage system and a method for using the same, including a carbon dioxide gasification subsystem; the carbon dioxide gasification subsystem is used to store the liquid carbon dioxide supplemented from the outside and perform a phase conversion on the liquid carbon dioxide to obtain supercritical carbon dioxide; the supercritical carbon dioxide storage subsystem is used to receive and store the supercritical carbon dioxide and serve as the carbon dioxide working fluid source for the supercritical carbon dioxide Brayton cycle system; the carbon dioxide gas recovery and utilization subsystem is used to recover, liquefy and re-inject the gaseous carbon dioxide leaked from the carbon dioxide gasification subsystem, the supercritical carbon dioxide storage subsystem and the supercritical carbon dioxide Brayton cycle system into the carbon dioxide gasification subsystem; the present invention ensures the stable storage and flowing supply of the carbon dioxide working fluid under various working conditions and guarantees the stable operation of the supercritical carbon dioxide Brayton cycle system.

Description

Technical Field

[0001] The present invention belongs to the technical field of supercritical carbon dioxide Brayton cycle systems, and particularly relates to a dense-phase carbon dioxide supply-storage system and a method for using the same. Background Art

[0002] The supercritical carbon dioxide Brayton cycle system is a new type of closed power cycle system. Compared with the steam Rankine cycle system of the same power level, it has the advantages of high cycle efficiency, high specific output power, and compact system structure; it has the potential to be applied in fields such as ship power systems, distributed energy, centralized energy storage, and waste heat and surplus energy power generation, and is an important way to realize the development of an efficient, compact, and low-carbon distributed energy power conversion system.

[0003] Currently, during the actual operation of the supercritical carbon dioxide Brayton cycle system, the following situations generally exist: 1. During the operation of the moving components in the system, there will be a certain amount of leakage at the equipment bearings and seals, and a small amount of gaseous carbon dioxide will leak at the valves, flanges, and interfaces in the system; 2. At the compressor and turbine in the system, it is necessary to extract low-temperature carbon dioxide to cool the moving components; it is necessary to extract high-temperature carbon dioxide at the turbine outlet to preheat the low-temperature carbon dioxide, and the carbon dioxide after heat exchange needs to be concentrated and recycled; 3. When the cycle system operates under variable load, the thermophysical properties of the working fluid in the carbon dioxide storage tank will change with the parameters of the upstream and downstream equipment, resulting in corresponding changes in the flow rate, pressure, and temperature of the inflowing and outflowing carbon dioxide; currently, the existing carbon dioxide storage tanks need to supplement or discharge carbon dioxide to maintain the stability of their pressure and temperature, thereby causing a large loss of working fluid; secondly, during the startup or shutdown process of the cycle system, the drastic changes in the temperature and pressure parameters of the working fluid in the system will cause large physical property changes in the working fluid in the carbon dioxide storage tank.

[0004] At present, the existing carbon dioxide treatment technology literature often treats carbon dioxide in one state or phase, and its operating range is single; for example: China's patent application "A stable supercritical carbon dioxide supply system and method" (application number: CN202010932376.1), in which the carbon dioxide is pressurized by a booster pump to provide gaseous carbon dioxide with stable pressure; China's patent application "A filling and debugging system for supercritical carbon dioxide Brayton cycle" (application number: CN202010864821.5) and China's patent application "A filling and gas replenishment system based on supercritical carbon dioxide working fluid" (application number: CN202110062023.5), in which a carbon dioxide compressor is used to increase the temperature and pressure of the gaseous carbon dioxide in the gas storage cylinder, and the temperature of the carbon dioxide is adjusted by a heat exchanger to form supercritical carbon dioxide with stable temperature and pressure, thereby achieving the purpose of supplying stable supercritical carbon dioxide to the circulation system.

[0005] In summary, in the supercritical carbon dioxide Brayton cycle system, carbon dioxide exists in the form of supercritical state, liquid state, gas state and gas-liquid coexistence state, and the existing gas filling, storage and utilization systems cannot meet the mutual conversion and storage of carbon dioxide in various states in the supercritical carbon dioxide Brayton cycle system, which seriously affects the operating stability of the circulation system. Summary of the invention

[0006] In view of the technical problems existing in the prior art, the present invention provides a dense phase carbon dioxide supply-storage system and a method of using the same to solve the technical problem that the existing gas filling, storage and utilization systems cannot satisfy the mutual conversion and storage of carbon dioxide in various states in a supercritical carbon dioxide Brayton cycle system, which seriously affects the operating stability of the circulation system.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The present invention provides a dense phase carbon dioxide supply-storage system, which is used for the carbon dioxide working medium filling and recovery process in a supercritical carbon dioxide Brayton cycle system; the dense phase carbon dioxide supply-storage system comprises a carbon dioxide gasification subsystem, a supercritical carbon dioxide storage subsystem and a carbon dioxide gas recovery and utilization subsystem;

[0009] The carbon dioxide gasification subsystem is used to store liquid carbon dioxide supplemented from the outside and to perform phase conversion on the liquid carbon dioxide to obtain supercritical carbon dioxide;

[0010] The supercritical carbon dioxide storage subsystem is used to receive and store the supercritical carbon dioxide and serve as a carbon dioxide working fluid source for the supercritical carbon dioxide Brayton cycle system;

[0011] The carbon dioxide gas recovery and utilization subsystem is used to recover, liquefy the gaseous carbon dioxide leaked from the carbon dioxide gasification subsystem, the supercritical carbon dioxide storage subsystem and the supercritical carbon dioxide Brayton cycle system, and reinject it into the carbon dioxide gasification subsystem.

[0012] Furthermore, the carbon dioxide gasification subsystem includes a liquid carbon dioxide storage tank, a liquid carbon dioxide booster pump, a heat exchanger, a gas-liquid mixer and a first heater;

[0013] The first inlet of the liquid carbon dioxide storage tank is connected to an external liquid carbon dioxide source, the working medium outlet of the liquid carbon dioxide storage tank is connected to the inlet end of the liquid carbon dioxide booster pump, the outlet end of the liquid carbon dioxide booster pump is connected to the tube side inlet of the heat exchanger, the tube side outlet of the heat exchanger is connected to the first inlet of the gas-liquid mixer, the outlet of the gas-liquid mixer is connected to the inlet end of the first heater, and the outlet end of the first heater is connected to the supercritical carbon dioxide storage subsystem.

[0014] Furthermore, the carbon dioxide gasification subsystem further includes a first pneumatic switch valve and a first one-way valve; the first pneumatic switch valve and the first one-way valve are sequentially arranged between the outlet end of the first heater and the supercritical carbon dioxide storage subsystem.

[0015] Furthermore, the supercritical carbon dioxide storage subsystem includes a supercritical carbon dioxide storage tank;

[0016] The supercritical carbon dioxide storage tank includes a tank body, a tank return pipe, a tank outlet pipe, a tank discharge pipe and a tank heater;

[0017] The tank body is provided with a tank inlet, a tank return port, a tank outlet and a tank discharge port, and one end of the tank inlet is connected to the carbon dioxide gasification subsystem;

[0018] The tank return pipe is arranged at the tank return port, and one end of the tank return pipe is connected to the working medium circulation outlet of the supercritical carbon dioxide Brayton cycle system; the other end of the tank return pipe extends to the bottom of the tank body and is deflected towards the tank outlet;

[0019] The tank outlet pipe is arranged at the tank outlet, one end of the tank outlet pipe extends into the tank body; the other end of the tank outlet pipe extends outside the tank body and is connected to the working medium circulation inlet of the supercritical carbon dioxide Brayton cycle system;

[0020] The storage tank discharge pipe is arranged at the storage tank discharge port, and one end of the storage tank discharge pipe extends to the inside of the storage tank body; the other end of the storage tank discharge pipe extends to the outside of the storage tank body and is connected to the carbon dioxide gas recovery and utilization subsystem;

[0021] The storage tank heater is arranged inside the storage tank body and is close to the bottom of the storage tank body; the storage tank heater is used to heat the supercritical carbon dioxide in the storage tank body.

[0022] Further, the storage tank body includes a metal inner tank layer, a carbon fiber winding layer, a heating tape layer, a heat insulation layer and a heat insulation outer shell which are arranged in sequence from inside to outside.

[0023] Further, a pressure stabilizing and buffering subsystem is also included; the pressure stabilizing and buffering subsystem includes a second pneumatic switch valve, a third pneumatic switch valve and a pressure stabilizing and buffering tank;

[0024] One end of the second pneumatic switch valve is connected to the working medium outlet of the supercritical carbon dioxide storage subsystem, the other end of the second pneumatic switch valve is connected to the inlet end of the pressure stabilizing and buffering tank, the outlet end of the pressure stabilizing and buffering tank is connected to one end of the third pneumatic switch valve, and the other end of the third pneumatic switch valve is connected to the working medium return port of the supercritical carbon dioxide storage subsystem.

[0025] Further, the pressure stabilizing and buffering tank includes a buffer tank body, a buffer tank inlet pipe, a buffer tank outlet pipe, a buffer tank heater and a buffer tank air bag;

[0026] The buffer tank body is a closed tank structure, and the buffer tank body is provided with a tank inlet and a tank outlet; the buffer tank inlet pipe is arranged at the tank inlet, one end of the buffer tank inlet pipe is connected to the second pneumatic switch valve, and the other end of the buffer tank inlet tank extends to the inside of the buffer tank body;

[0027] The buffer tank outlet pipe is arranged at the tank outlet, one end of the buffer tank outlet pipe extends to the inside of the buffer tank body, and the other end of the buffer tank outlet pipe is connected to the third pneumatic switch valve; the buffer tank air bag is arranged inside the buffer tank body and is close to the top end of the buffer tank body.

[0028] Further, the carbon dioxide gas recovery and utilization subsystem includes a gas collection tank, a filter, a carbon dioxide ejector, a second heater and a carbon dioxide membrane separator;

[0029] The gas leakage ports of the liquid carbon dioxide storage tank, the gas leakage ports of the supercritical carbon dioxide storage subsystem and the gas leakage ports of the supercritical carbon dioxide Brayton cycle system are all connected to the inlet end of the gas collection tank;

[0030] The outlet end of the gas collector is connected to the inlet end of the filter, and the outlet end of the filter is connected to the first inlet end of the carbon dioxide ejector; one end of the second heater is connected to the outlet end of the first heater, and the other end of the second heater is connected to the second inlet end of the carbon dioxide ejector;

[0031] The outlet end of the carbon dioxide ejector is connected to the inlet end of the carbon dioxide membrane separator, the outlet end of the carbon dioxide separator is connected to the shell side inlet of the heat exchanger, and the shell side outlet of the heat exchanger is connected to the second inlet of the gas-liquid mixer.

[0032] Furthermore, the carbon dioxide membrane separator includes a primary separator and a secondary separator;

[0033] The outlet end of the carbon dioxide ejector is connected to the inlet end of the primary separator, the first outlet of the primary separator is connected to the inlet end of the secondary separator, and the second outlet of the primary separator serves as an impurity gas treatment interface;

[0034] The first outlet of the secondary separator is connected to the shell side inlet of the heat exchanger, and the second outlet of the secondary separator is connected to the inlet end of the primary separator.

[0035] The present invention also provides a method for using a dense-phase carbon dioxide supply-storage system, including:

[0036] Storing the liquid carbon dioxide supplemented from the outside by using the carbon dioxide gasification subsystem;

[0037] Converting the phase of the stored liquid carbon dioxide by using the carbon dioxide gasification subsystem to obtain supercritical carbon dioxide;

[0038] Filling the supercritical carbon dioxide into the supercritical carbon dioxide subsystem for storage;

[0039] Using the supercritical carbon dioxide subsystem to provide a stable carbon dioxide working fluid source for the supercritical carbon dioxide Brayton cycle system;

[0040] Using the carbon dioxide gas recovery and utilization subsystem to recover, liquefy the gaseous carbon dioxide leaked from the carbon dioxide gasification subsystem, the supercritical carbon dioxide storage subsystem and the supercritical carbon dioxide Brayton cycle system and reinject it into the carbon dioxide gasification subsystem.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] The present invention provides a dense-phase carbon dioxide supply-storage system and a method for using the same. By setting up a carbon dioxide gasification subsystem, the conversion of liquid carbon dioxide into supercritical carbon dioxide is realized, and the supercritical carbon dioxide storage subsystem is used for storage and stable supply to the supercritical carbon dioxide Brayton cycle system. At the same time, by setting up a carbon dioxide gas recovery and utilization subsystem, the recovery of the leaked gaseous carbon dioxide in the carbon dioxide gasification subsystem, the supercritical carbon dioxide storage subsystem and the supercritical carbon dioxide Brayton cycle system is realized, avoiding the leakage and waste of the carbon dioxide working medium and reducing carbon emissions. The present invention can meet the requirements of the mutual conversion and storage of various states of carbon dioxide in the supercritical carbon dioxide Brayton cycle system, realizing a wide operating range of the system. At the same time, it ensures the stable storage and flow supply of the carbon dioxide working medium under various working conditions, ensuring the stable operation of the supercritical carbon dioxide Brayton cycle system.

[0043] Further, the carbon dioxide gasification subsystem adopts a combination form of a liquid carbon dioxide storage tank, a liquid carbon dioxide booster pump, a heat exchanger, a gas-liquid mixer and a first heater, realizing that no refrigeration is required during the process of pressurized reinjection of gaseous carbon dioxide, simplifying the system structure and saving the cost of the primary investment.

[0044] Further, by setting a storage tank discharge port on the storage tank body, the discharge requirement of non-condensable gases is realized, and the automatic separation and filtration of non-condensable gases carried by the supercritical carbon dioxide working medium after long-term operation can be carried out, which is convenient for cleaning and maintenance.

[0045] Further, by setting up a pressure stabilizing and buffering subsystem, it plays a role in regulating and balancing the flow rate, temperature and pressure of the working medium.

[0046] Further, by setting a carbon dioxide membrane separator in the gaseous carbon dioxide recovery and utilization subsystem, the non-condensable gases in the carbon dioxide are removed by means of membrane separation, and the system structure is simple and the removal efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a structural block diagram of the dense-phase carbon dioxide supply-storage system described in the present invention;

[0048] Figure 2 is a schematic structural diagram of the supercritical carbon dioxide storage tank in the present invention;

[0049] Figure 3 is a schematic structural diagram of the pressure stabilizing and buffering tank in the present invention.

[0050] Among them, 1 is a carbon dioxide tanker, 2 is a liquid carbon dioxide storage tank, 3 is a storage tank pre-cooler, 4 is a liquid carbon dioxide booster pump, 5 is a heat exchanger, 6 is a gas-liquid mixer, 7 is a first heater, 8 is a first pneumatic on-off valve, 9 is a first check valve, 10 is a supercritical carbon dioxide storage tank, 11 is a second pneumatic on-off valve, 12 is a second check valve, 13 is a third pneumatic on-off valve, 14 is a third check valve, 15 is a pressure stabilizing buffer tank, 16 is a fourth check valve, 17 is a gas collection tank, 18 is a fifth check valve, 19 is a filter, 20 is a first pneumatic regulating valve, 21 is a carbon dioxide ejector, 22 is a second pneumatic regulating valve, 23 is a second heater, 24 is a primary separator, 25 is a secondary separator, 26 is a sixth check valve, 27 is a fourth pneumatic on-off valve; 101 is the storage tank body, 102 is the storage tank return pipe, 103 is the storage tank outlet pipe, 104 is the storage tank discharge pipe, 105 is the storage tank heater, 106 is the tracing heating tape layer, 107 is the first liquid level gauge, 108 is the first pressure sensor, 109 is the first temperature sensor, 1010 is the second pressure sensor, 1011 is the second temperature sensor, 1012 is the second liquid level gauge, 1013 is the safety valve; 151 is the buffer tank body, 152 is the buffer tank inlet pipe, 153 is the buffer tank outlet pipe, 154 is the buffer tank heater, 155 is the buffer air bag. Detailed implementation mode

[0051] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the following specific embodiments are used to further elaborate on the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0052] As shown in the attached Figures 1-3 figure, the present invention provides a dense-phase carbon dioxide supply-storage system, which is used for the carbon dioxide working medium filling and recovery process in a supercritical carbon dioxide Brayton cycle system; the dense-phase carbon dioxide supply-storage system includes a carbon dioxide gasification subsystem, a supercritical carbon dioxide storage subsystem, a carbon dioxide gas recovery and utilization subsystem, a pressure stabilizing buffer subsystem and an automatic control subsystem.

[0053] The carbon dioxide gasification subsystem is used to store liquid carbon dioxide supplemented from the outside, and can perform phase conversion on liquid carbon dioxide to obtain supercritical carbon dioxide; the supercritical carbon dioxide storage subsystem is used to receive and store the supercritical carbon dioxide, and serve as the source of carbon dioxide working fluid for the supercritical carbon dioxide Brayton cycle system; the carbon dioxide recovery and utilization subsystem is used to recover, liquefy and re-inject gaseous carbon dioxide leaked from the carbon dioxide gasification subsystem, the supercritical carbon dioxide storage subsystem and the supercritical carbon dioxide Brayton cycle system into the carbon dioxide gasification subsystem, and separate impurity gases in the carbon dioxide; the pressure stabilizing buffer subsystem is used to buffer and balance the flow, temperature or pressure of the supercritical carbon dioxide in the supercritical carbon dioxide storage subsystem; the automatic control subsystem is used to automatically control the carbon dioxide gasification subsystem, the supercritical carbon dioxide storage subsystem, the carbon dioxide gas recovery and utilization subsystem and the pressure stabilizing buffer subsystem, so as to automatically realize the filling, gas replenishment and stable circulation operation of the carbon dioxide working fluid.

[0054] In the present invention, the carbon dioxide gasification subsystem includes a liquid carbon dioxide storage tank 2, a storage tank precooler 3, a liquid carbon dioxide booster pump 4, a heat exchanger 5, a gas-liquid mixer 6, a first heater 7, a first pneumatic switch valve 8, a first check valve 9 and a sixth check valve 26; the first inlet of the liquid carbon dioxide storage tank 2 is connected to an external liquid carbon dioxide source, and the external liquid carbon dioxide source adopts a carbon dioxide tank truck 1; the working fluid outlet of the liquid carbon dioxide storage tank 2 is connected to one end of the storage tank precooler 3, and the other end of the storage tank precooler 3 is connected to the inlet end of the liquid carbon dioxide pump 4, and the outlet end of the liquid carbon dioxide booster pump 4 is divided into two paths, one of which is connected to the pipe side inlet of the heat exchanger 5, and the other is connected to the pipe side inlet of the heat exchanger 5. The pipe side outlet of the heat exchanger 5 is connected to the first inlet of the gas-liquid mixer 6, and the other end of the sixth one-way valve 26 is connected to the second inlet of the liquid carbon dioxide storage tank 2; the outlet of the gas-liquid mixer 6 is connected to the inlet end of the first heater 7, and the outlet end of the first heater 7 is divided into two paths, one of which is connected to one end of the first pneumatic switch valve 8, and the other is connected to the second heater 23 in the carbon dioxide gas recovery subsystem; the other end of the first start-up switch valve 8 is connected to one end of the first one-way valve 9, and the other end of the first one-way valve 9 is connected to the supercritical carbon dioxide storage tank 10 in the supercritical carbon dioxide storage subsystem.

[0055] The carbon dioxide gasification subsystem in the present invention is used for storing the liquid carbon dioxide supplemented from the outside, and is also used for phase conversion of the liquid carbon dioxide to obtain supercritical carbon dioxide and supplement the supercritical carbon dioxide into the supercritical carbon dioxide storage subsystem; wherein, the liquid carbon dioxide supplemented from the outside is transported by a carbon dioxide tank truck 1 and filled into a liquid carbon dioxide storage tank 2, the pressure of the liquid carbon dioxide is 2 to 2.5 MPa, and the temperature of the liquid carbon dioxide is -20 to -18 °C; the liquid carbon dioxide is pressurized by the liquid carbon dioxide booster pump 4 and then enters the gas-liquid mixer 6 after being heated by the heat exchanger 5; the lower-layer dense-phase liquid in the gas-liquid mixer 6 enters the first heater 7 and is heated to a temperature of 32 °C and a pressure of 7.4 MPa to obtain supercritical carbon dioxide; then, the first pneumatic switch valve 8 and the first one-way valve 9 are opened, and the supercritical carbon dioxide enters the supercritical carbon dioxide storage tank 10 successively through the first pneumatic switch valve 8 and the first one-way valve 9 to complete the air supplement operation of the supercritical carbon dioxide.

[0056] In the present invention, the supercritical carbon dioxide storage subsystem includes a supercritical carbon dioxide storage tank 10; the supercritical carbon dioxide storage tank 10 includes a tank body 101, a tank return pipe 102, a tank outlet pipe 103, a tank discharge pipe 104 and a tank heater 105; the tank body 101 includes a metal inner liner layer, a carbon fiber winding layer, a heating tape layer 106, a heat insulation layer and a heat insulation outer shell which are arranged in sequence from inside to outside.

[0057] The storage tank body 101 is provided with a storage tank inlet, a storage tank return port, a storage tank outlet and a storage tank discharge port. One end of the storage tank inlet is connected to the first one-way valve 9 in the carbon dioxide gasification subsystem; the storage tank return port is located at the top of the storage tank body 101, and the storage tank return pipe 102 is arranged at the storage tank return port; one end of the storage tank return pipe 102 is connected to the working fluid circulation outlet of the supercritical carbon dioxide Brayton cycle system; the other end of the storage tank return pipe 102 extends to the bottom of the storage tank body 101 and is deflected towards the storage tank outlet; the storage tank outlet is located at the right bottom end of the storage tank body 101, and the storage tank outlet pipe 103 is arranged at the storage tank outlet; one end of the storage tank outlet pipe 103 extends into the storage tank body 101; the other end of the storage tank outlet pipe 103 extends to the outside of the storage tank body 101 and is connected to the working fluid inlet of the supercritical carbon dioxide Brayton cycle system; the storage tank discharge port is located at the left bottom end of the storage tank body 101, and the storage tank discharge pipe 104 is arranged at the storage tank discharge port; one end of the storage tank discharge pipe 104 extends into the storage tank body 101; the other end of the storage tank discharge pipe 104 extends to the outside of the storage tank body 101 and is connected to the fourth one-way valve 16 in the carbon dioxide gas recovery and utilization subsystem; the storage tank heater 105 is arranged inside the storage tank body 101 and is close to the bottom of the storage tank body 101; the storage tank heater 105 is used to heat the supercritical carbon dioxide in the storage tank body 101.

[0058] The supercritical carbon dioxide storage subsystem in the present invention is used to store supercritical carbon dioxide and serve as the source of the carbon dioxide working fluid of the supercritical carbon dioxide Brayton cycle system; at the same time, it can maintain the temperature and pressure stability of the supercritical carbon dioxide in the supercritical carbon dioxide storage tank; specifically, the supercritical carbon dioxide storage tank 10 can receive the filling of supercritical carbon dioxide from the carbon dioxide gasification subsystem, maintain the temperature and pressure stability of the supercritical carbon dioxide in the storage tank body 101, and provide carbon dioxide working fluid to the supercritical carbon dioxide Brayton cycle system; preferably, the heat preservation shell is an aluminum shell, and a safety valve 1013 is arranged at the storage tank return port.

[0059] In the present invention, the carbon dioxide gas recovery and utilization subsystem includes a fourth one-way valve 16, a gas collection tank 17, a fifth one-way valve 18, a filter 19, a first pneumatic control valve 20, a carbon dioxide ejector 21, a second pneumatic control valve 22, a second heater, a carbon dioxide membrane separator and a fourth pneumatic switch valve 27.

[0060] The gas leakage port of the liquid carbon dioxide storage tank 2 is connected to one end of the fourth pneumatic switch valve 27, and the other end of the fourth pneumatic switch valve 27 is connected to one end of the fifth one-way valve 18; the storage tank discharge pipe 104 in the supercritical carbon dioxide storage tank 10 and the gas leakage port of the supercritical carbon dioxide Brayton cycle system are both connected to one end of the fourth one-way valve 16; the other end of the fourth one-way valve 16 and the other end of the fifth one-way valve 18 are both connected to the inlet end of the gas collection tank 17.

[0061] The outlet end of the gas collector 17 is connected to the inlet end of the filter 19, and the outlet end of the filter 19 is connected to the first inlet end of the carbon dioxide ejector 21; one end of the second heater 23 is connected to the outlet end of the first heater 7, the other end of the second heater 23 is connected to one end of the second pneumatic regulating valve 22, and the other end of the second pneumatic regulating valve 22 is connected to the second inlet end of the carbon dioxide ejector 21.

[0062] The outlet end of the carbon dioxide ejector 21 is connected to the inlet end of the carbon dioxide membrane separator, the outlet end of the carbon dioxide membrane separator is connected to the tube side inlet of the heat exchanger 5, and the shell side outlet of the heat exchanger 5 is connected to the second inlet of the gas-liquid mixer 6.

[0063] In the present invention, the carbon dioxide membrane separator includes a primary separator 24 and a secondary separator 25; the outlet end of the carbon dioxide ejector 21 is connected to the inlet end of the primary separator 24, the first outlet of the primary separator 24 is connected to the inlet end of the secondary separator 25, and the second outlet of the primary separator 24 serves as an impurity gas treatment interface; wherein, the impurity gas interface is used to discharge the unpermeated gas in the primary separator 24 and the secondary separator 25; the first outlet of the secondary separator 25 is connected to the shell side inlet of the heat exchanger 5, and the second outlet of the secondary separator 25 is connected to the inlet end of the primary separator 24.

[0064] The carbon dioxide gas recovery and utilization subsystem of the present invention is used to re-liquefy the gaseous carbon dioxide leaked during the operation of the system and inject it back into the system; among them, the gaseous carbon dioxide leaked from the supercritical carbon dioxide Brayton cycle system and the part of the gaseous carbon dioxide vaporized due to temperature or pressure in the supercritical carbon dioxide storage tank 10 enter the gas collection tank 17 through the fourth one-way valve 16; the part of the gaseous carbon dioxide vaporized from the liquid carbon dioxide storage tank 2 enters the gas collection tank 17 in sequence through the fourth pneumatic switch valve 27 and the fifth one-way valve 18; when the gaseous carbon dioxide in the gas collection tank 17 reaches the preset pressure, the first pneumatic regulating valve 20 is opened and at the same time the second start regulating valve 22 is opened to jointly introduce the low-temperature and low-pressure gaseous carbon dioxide and the high-pressure carbon dioxide heated by the second heater 23 into the carbon dioxide ejector 21; the high-temperature and high-pressure carbon dioxide drives the low-temperature and low-pressure gaseous carbon dioxide to mix through high-speed flow, forming medium-temperature and medium-pressure gaseous carbon dioxide, and then passing through the primary separator 24 and the secondary separator 25 in sequence, so as to completely separate the pure gaseous carbon dioxide from other impurity gases; the separated pure gaseous carbon dioxide enters the heat exchanger 5 to exchange heat and liquefy with the low-temperature liquid carbon dioxide, and then is re-injected into the gas-liquid mixer 6; among them, the unpermeated gas in the primary separator 24 and the secondary separator 25 is discharged through the impurity gas treatment interface.

[0065] In the present invention, the pressure stabilizing and buffering subsystem includes a second pneumatic switch valve 11, a second one-way valve 12, a third pneumatic switch valve 13, a third one-way valve 14 and a pressure stabilizing and buffering tank 15; one end of the second pneumatic switch valve 11 is connected to the working medium outlet of the supercritical carbon dioxide storage subsystem; specifically, one end of the second pneumatic switch valve 11 is connected to the storage tank outlet pipe 103; the other end of the second pneumatic switch valve 11 is connected to one end of the second one-way valve 12, and the other end of the second one-way valve 12 is connected to the inlet end of the pressure stabilizing and buffering tank 15; the outlet end of the pressure stabilizing and buffering tank 15 is connected to one end of the third one-way valve 14, and the other end of the third one-way valve 14 is connected to the working medium return port of the supercritical carbon dioxide storage subsystem; specifically, the other end of the third one-way valve 14 is connected to the storage tank return pipe 102.

[0066] The pressure stabilizing buffer tank 15 includes a buffer tank body 151, a buffer tank inlet pipe 152, a buffer tank outlet pipe 153, a buffer tank heater 154 and a buffer tank airbag 155; the buffer tank body 151 is a closed tank structure, and the buffer tank heater 154 is arranged on the buffer tank body 151; wherein, the buffer tank heater 154 is used to heat the supercritical carbon dioxide in the buffer tank body 151 to adjust the flow rate, temperature and pressure of the supercritical carbon dioxide in the buffer tank body 151; the buffer tank body 151 is provided with a tank inlet and a tank outlet; the buffer tank inlet pipe 152 is arranged at the tank inlet, one end of the buffer tank inlet pipe 152 is connected to the second one-way valve 11, and the other end of the buffer tank inlet pipe 152 extends into the interior of the buffer tank body 151; the buffer tank outlet pipe 153 is arranged at the tank outlet, one end of the buffer tank outlet pipe 153 extends into the interior of the buffer tank body 151, and the other end of the buffer tank outlet pipe 153 is connected to the third one-way valve 14; the buffer tank airbag 155 is arranged inside the buffer tank body 151 and is arranged near the top of the buffer tank body 151.

[0067] When the supercritical carbon dioxide Brayton cycle system operates normally, the supercritical carbon dioxide enters the circulation system through the storage tank outlet pipe 102 and then flows back into the supercritical carbon dioxide storage tank through the storage tank return pipe 102; when the flow rate, temperature or pressure of the supercritical carbon dioxide changes, the pressure stabilizing buffer tank 15 is used to adjust and balance the flow rate, temperature and pressure of the supercritical carbon dioxide.

[0068] In the present invention, the automatic control subsystem includes an industrial control computer, a first liquid level gauge 107, a first pressure sensor 108, a second temperature sensor 109, a second pressure sensor 1010, a second temperature sensor 1011 and a second liquid level gauge 1012; the output ends of the first liquid level gauge 107, the first pressure sensor 108, the second temperature sensor 109, the second pressure sensor 1010, the second temperature sensor 1011 and the second liquid level gauge 1012 are all connected to the input end of the industrial control computer; the output end of the industrial control computer is connected to the liquid carbon dioxide booster pump 4, the first heater 7, the first pneumatic switch valve 8, the second pneumatic switch valve 11, the third pneumatic switch valve 13, the first pneumatic regulating valve 20, the second pneumatic regulating valve 22, the second heater 23, the fourth pneumatic switch valve 27, the storage tank heater 105, the heat tracing layer 106 and the buffer tank heater 154.

[0069] The first liquid level gauge 107 is arranged at the bottom of the storage tank body 101, and the second liquid level gauge 1012 is arranged on the side wall of the storage tank body 101 and above the storage tank outlet; the first liquid level gauge 107 and the second liquid level gauge 1012 are respectively used for collecting the liquid level data at their respective positions; the first pressure sensor 108 and the first temperature sensor 109 are both arranged at the storage tank return port, the first pressure sensor 108 is used for collecting the working medium pressure data at the storage tank return port, and the first temperature sensor 109 is used for collecting the working medium temperature data at the storage tank return port; the second pressure sensor 1010 and the second temperature sensor 1011 are both arranged at the storage tank outlet, the second pressure sensor 1010 is used for collecting the working medium pressure data at the storage tank outlet, and the second temperature sensor 1011 is used for collecting the working medium temperature data at the storage tank outlet; the industrial control computer is used for generating corresponding control instructions according to the liquid level data, the working medium pressure data and the working medium temperature data, and sending the control instructions to the connected liquid carbon dioxide booster pump 4, the first heater 7, the first pneumatic switch valve 8, the second pneumatic switch valve 11, the third pneumatic switch valve 13, the first pneumatic regulating valve 20, the second pneumatic regulating valve 22, the second heater 23, the fourth pneumatic switch valve 27, the storage tank heater 105, the heat tracing layer 106 and the buffer tank heater 154 respectively to realize the automatic control operation of the equipment.

[0070] The automatic control subsystem in the present invention is used for automatically controlling the carbon dioxide gasification subsystem, the supercritical carbon dioxide storage subsystem and the carbon dioxide gas recovery and utilization subsystem, and automatically realizing the functions of carbon dioxide filling or air replenishment and stable operation; specifically, by detecting the working medium temperature, the working medium pressure in the circulation loop and the externally input control instructions, the automatic operation adjustment of the equipment connected thereto is controlled.

[0071] The present invention also provides a use method of a dense-phase carbon dioxide supply-storage system, including the following steps:

[0072] Using the carbon dioxide gasification subsystem to store the liquid carbon dioxide supplemented from the outside;

[0073] Using the carbon dioxide gasification subsystem to perform phase conversion on the stored liquid carbon dioxide to obtain supercritical carbon dioxide;

[0074] Filling the supercritical carbon dioxide into the supercritical carbon dioxide subsystem for storage;

[0075] Using the supercritical carbon dioxide subsystem to provide a carbon dioxide working medium source with stable working conditions for the supercritical carbon dioxide Brayton cycle system;

[0076] Using the carbon dioxide gas recovery and utilization subsystem, the gaseous carbon dioxide leaked from the carbon dioxide gasification subsystem, the supercritical carbon dioxide storage subsystem and the supercritical carbon dioxide Brayton cycle system is recovered, liquefied and reinjected into the carbon dioxide gasification subsystem.

[0077] Working principle:

[0078] When the dense-phase carbon dioxide supply-storage system of the present invention works, the specific process is as follows:

[0079] S1. Carbon dioxide filling process

[0080] The liquid carbon dioxide is transported and filled into the liquid carbon dioxide storage tank 2 by the carbon dioxide tank truck 1. When carbon dioxide filling is required, the liquid carbon dioxide booster pump 4 and the first heater are started to pressurize and heat up the liquid carbon dioxide output from the liquid carbon dioxide storage tank 2; when the temperature and pressure of the carbon dioxide reach the set temperature value and the set pressure value, that is, supercritical carbon dioxide is obtained, and the supercritical carbon dioxide is filled into the supercritical carbon dioxide storage tank 10 by opening the first heater 7 and the first pneumatic switch valve 8; wherein, the set temperature value is higher than 31 °C, and the set pressure value is higher than 7.4 MPa; by adding a flow meter, the filling amount of the supercritical carbon dioxide is automatically obtained, and then when the filling amount reaches the preset value, the first pneumatic switch valve 8 is closed, and the first heater 7 stops working to end the filling process; wherein, a first one-way valve 9 is arranged between the first pneumatic switch valve 8 and the supercritical carbon dioxide storage tank to prevent the working medium from flowing back during the filling process.

[0081] S2. Gaseous carbon dioxide recovery and impurity removal process

[0082] During the system cycle, the gasified gaseous carbon dioxide needs to be recovered and the non-condensable gas therein is removed; specifically, the gaseous carbon dioxide gasified when the supercritical carbon dioxide storage tank 10 and the supercritical carbon dioxide Brayton cycle system operate flows into the gas collection tank 17 through the fourth one-way valve 16; the gaseous carbon dioxide gasified in the liquid carbon dioxide storage tank 2 flows into the gas collection tank 17 through the fifth one-way valve 18 for storage and pressure stabilization.

[0083] Part of the high-temperature and high-pressure liquid carbon dioxide enters the carbon dioxide ejector 21 after being heated by the second heater 23 and throttled by the second pneumatic control valve 22. The high-temperature and high-pressure liquid carbon dioxide is mixed with the low-temperature and low-pressure gaseous carbon dioxide from the gas collection tank 17 to form medium-pressure and low-temperature carbon dioxide. Among them, the pressure of the medium-pressure and low-temperature carbon dioxide is 4-6 MPa, and its temperature < 20 °C. Then, after the medium-pressure and low-temperature carbon dioxide is separated by the first-stage separator 24, the impurity gas is discharged along the impurity gas treatment interface or continues to be treated, and the separated gas is further separated by the second-stage separator 25. The separated pure carbon dioxide flows out of the separation area to the tube side of the heat exchanger 5. Among them, the intercepted gas of the second-stage separator 26 returns to the inlet of the first-stage separator 24 for re-separation. The gaseous carbon dioxide after separation exchanges heat with the high-temperature and high-pressure liquid carbon dioxide through the heat exchanger 5 and then enters the gas-liquid mixer 6 for reuse.

[0084] S3. Supercritical carbon dioxide storage process

[0085] The supercritical carbon dioxide in the storage tank body 101 flows out through the storage tank outlet pipe 103 and enters the supercritical carbon dioxide Brayton cycle system. The supercritical carbon dioxide in the supercritical carbon dioxide Brayton cycle system returns to the storage tank body 101 through the storage tank return pipe 102. The industrial control computer in the automatic control subsystem monitors the working medium pressure and working medium temperature data at the storage tank return port by collecting the monitoring data of the first pressure sensor 108 and the first temperature sensor 109. The industrial control computer monitors the working medium pressure and working medium temperature data at the storage tank outlet by collecting the monitoring data of the second pressure sensor 1010 and the second temperature sensor 1010 to compare and analyze the uneven temperature and pressure distribution phenomenon in the storage tank body 101. When the temperature in the storage tank body 101 is lower than the set temperature, the storage tank heater 105 is turned on to heat the carbon dioxide in the storage tank body. When the pressure and temperature in the storage tank body 101 reach the preset values, the storage tank heater 105 is turned off. When the pressure in the storage tank body 101 is over-pressurized or the non-condensable gas accumulates too much in the upper part of the tank body 101, the excess gas is returned to the gas recovery and impurity removal subsystem. The liquid level in the storage tank is detected by the first liquid level gauge and the second liquid level gauge. When the liquid level is too low, the carbon dioxide gasification and filling process is started.

[0086] S4. Power system circulating operation and pressure stabilizing process

[0087] For the multi-condition and wide-range operating conditions of the supercritical carbon dioxide Brayton cycle, through a pressure stabilizing and buffering subsystem, damping devices are added to stabilize the pressure and temperature fluctuations of the system; when the system is tested or does not need to be adjusted for operation, the second pneumatic switch valve 11 and the third pneumatic switch valve 13 are closed to isolate the pressure stabilizing and buffering tank 15; when the working fluid flow rate in the system is too large, the second pneumatic switch valve 11 is controlled to open, and the excessive carbon dioxide working fluid flows into the pressure stabilizing and buffering tank 15; when the working fluid flow rate in the system is too low, the control system opens the third pneumatic switch valve 13.

[0088] In the present invention, when the temperature or pressure of the working fluid in the storage tank body is lower than the set value, the heating tape layer 106 and the storage tank heater 105 are turned on to ensure that the temperature and pressure in the tank are higher than the set value; in the buffer tank body 151, by adjusting the gas pressure in the buffer tank airbag 155, the pressure level and volume in the buffer tank body 151 are preset. When the temperature of the working fluid in the buffer tank body 151 is lower than the set value, the tank body buffer tank heater 154 is turned on to ensure that the temperature in the buffer tank body 151 is higher than the set value.

[0089] The dense-phase carbon dioxide supply-storage system and its usage method described in the present invention adopt a combination of a carbon dioxide gasification subsystem, a supercritical carbon dioxide storage subsystem, a carbon dioxide gas recovery and utilization subsystem, and a pressure stabilizing and buffering subsystem to effectively address problems such as increased return liquid flow, decreased outlet flow, excessive temperature, turbine shutdown, and overpressure or insufficient liquid supply in the storage tank during the self-starting process caused by upstream conditions; the present invention solves the problems in the process of filling and recovering gaseous carbon dioxide in a supercritical carbon dioxide Brayton cycle system, realizes the function of converting gaseous and liquid carbon dioxide into supercritical state for storage and use, meets the stable operation and convenient maintenance of the cycle system, does not cause waste of carbon dioxide working fluid, and reduces carbon emissions; adopts a membrane separation method to remove non-condensable gases in carbon dioxide, and the solution is simple; at the same time, it also solves the problem that during the process of pressurizing and reinjecting gaseous carbon dioxide, refrigeration is not required, the system is simplified, and the primary investment is saved; it can solve the automatic separation and filtration of non-condensable gases, liquids, and solid particles carried by supercritical carbon dioxide working fluid during long-term operation, facilitating cleaning and maintenance; it meets the filling of dense-phase carbon dioxide in a supercritical carbon dioxide Brayton cycle power system, and at the same time facilitates the stable supply, centralized storage, and cyclic collection of various phase states of carbon dioxide during the operation of the power system.

[0090] The above embodiments are only one of the implementation manners capable of realizing the technical solution of the present invention. The scope of protection required by the present invention is not limited only by this embodiment, but also includes any changes, substitutions, and other implementation manners that are easily conceivable by any person skilled in the art within the technical scope disclosed by the present invention.

Claims

1. A dense-phase carbon dioxide supply-storage system, characterized in that, For the carbon dioxide working medium filling and recovery process in a supercritical carbon dioxide Brayton cycle system; the dense-phase carbon dioxide supply-storage system includes a carbon dioxide gasification subsystem, a supercritical carbon dioxide storage subsystem, and a carbon dioxide gas recovery and utilization subsystem; The carbon dioxide gasification subsystem is used to store the liquid carbon dioxide supplemented from the outside and perform phase conversion on the liquid carbon dioxide to obtain supercritical carbon dioxide; The supercritical carbon dioxide storage subsystem is used to receive and store the supercritical carbon dioxide and serve as the carbon dioxide working medium source for the supercritical carbon dioxide Brayton cycle system; The carbon dioxide gas recovery and utilization subsystem is used to recover, liquefy, and re-inject the gaseous carbon dioxide leaked from the carbon dioxide gasification subsystem, the supercritical carbon dioxide storage subsystem, and the supercritical carbon dioxide Brayton cycle system into the carbon dioxide gasification subsystem; The carbon dioxide gasification subsystem includes a liquid carbon dioxide storage tank (2), a liquid carbon dioxide booster pump (4), a heat exchanger (5), a gas-liquid mixer (6), and a first heater (7); The first inlet of the liquid carbon dioxide storage tank (2) is connected to an external liquid carbon dioxide source, the working medium outlet of the liquid carbon dioxide storage tank (2) is connected to the inlet end of the liquid carbon dioxide booster pump (4), the outlet end of the liquid carbon dioxide booster pump (4) is connected to the tube-side inlet of the heat exchanger (5), the tube-side outlet of the heat exchanger (5) is connected to the first inlet of the gas-liquid mixer (6), the outlet of the gas-liquid mixer (6) is connected to the inlet end of the first heater (7), and the outlet end of the first heater (7) is connected to the supercritical carbon dioxide storage subsystem; The supercritical carbon dioxide storage subsystem includes a supercritical carbon dioxide storage tank (10); The supercritical carbon dioxide storage tank (10) includes a tank body (101), a tank return pipe (102), a tank outlet pipe (103), a tank discharge pipe (104), and a tank heater (105); The tank body (101) is provided with a tank inlet, a tank return port, a tank outlet, and a tank discharge port, and one end of the tank inlet is connected to the carbon dioxide gasification subsystem; The tank return pipe (102) is arranged at the tank return port, one end of the tank return pipe (102) is connected to the working medium circulation outlet of the supercritical carbon dioxide Brayton cycle system; the other end of the tank return pipe (102) extends to the bottom of the tank body (101) and is deflected in the direction of the tank outlet; The tank outlet pipe (103) is arranged at the tank outlet, one end of the tank outlet pipe (103) extends into the interior of the tank body (101); the other end of the tank outlet pipe (103) extends outside the tank body (101) and is connected to the working medium circulation inlet of the supercritical carbon dioxide Brayton cycle system; The storage tank discharge pipe (104) is arranged at the storage tank discharge port, and one end of the storage tank discharge pipe (104) extends into the interior of the storage tank body (101); the other end of the storage tank discharge pipe (104) extends to the outside of the storage tank body (101) and is connected to the carbon dioxide gas recovery and utilization subsystem; The storage tank heater (105) is arranged inside the storage tank body (101) and is close to the bottom of the storage tank body (101); the storage tank heater (105) is used to heat the supercritical carbon dioxide in the storage tank body (101); The carbon dioxide gas recovery and utilization subsystem includes a gas collection tank (17), a filter (19), a carbon dioxide ejector (21), a second heater (23) and a carbon dioxide membrane separator; The gas leakage ports of the liquid carbon dioxide storage tank (2), the gas leakage ports of the supercritical carbon dioxide storage subsystem and the gas leakage ports of the supercritical carbon dioxide Brayton cycle system are all connected to the inlet end of the gas collection tank (17); The outlet end of the gas collection tank (17) is connected to the inlet end of the filter (19), and the outlet end of the filter (19) is connected to the first inlet end of the carbon dioxide ejector (21); one end of the second heater (23) is connected to the outlet end of the first heater (7), and the other end of the second heater (23) is connected to the second inlet end of the carbon dioxide ejector (21); The outlet end of the carbon dioxide ejector (21) is connected to the inlet end of the carbon dioxide membrane separator, the outlet end of the carbon dioxide membrane separator is connected to the shell side inlet of the heat exchanger (5), and the shell side outlet of the heat exchanger (5) is connected to the second inlet of the gas-liquid mixer (6).

2. The dense-phase carbon dioxide supply and storage system according to claim 1, wherein The carbon dioxide gasification subsystem further includes a first pneumatic switch valve (8) and a first one-way valve (9); the first pneumatic switch valve (8) and the first one-way valve (9) are sequentially arranged between the outlet end of the first heater (7) and the supercritical carbon dioxide storage subsystem.

3. The dense-phase carbon dioxide supply and storage system according to claim 1, characterized in that The storage tank body (101) includes a metal inner liner layer, a carbon fiber winding layer, a heating tape layer (106), a heat insulation layer and a heat insulation outer shell which are arranged in sequence from the inside to the outside.

4. A dense-phase carbon dioxide supply and storage system according to claim 1, characterized in that, It further includes a pressure stabilizing and buffering subsystem; the pressure stabilizing and buffering subsystem includes a second pneumatic switch valve (11), a third pneumatic switch valve (13) and a pressure stabilizing and buffering tank (15); One end of the second pneumatic switch valve (11) is connected to the working medium outlet of the supercritical carbon dioxide storage subsystem, the other end of the second pneumatic switch valve (11) is connected to the inlet end of the pressure stabilizing and buffering tank (15), the outlet end of the pressure stabilizing and buffering tank (15) is connected to one end of the third pneumatic switch valve (13), and the other end of the third pneumatic switch valve (13) is connected to the working medium return port of the supercritical carbon dioxide storage subsystem.

5. A dense-phase carbon dioxide supply and storage system according to claim 4, characterized in that, The pressure stabilizing buffer tank (15) includes a buffer tank body (151), a buffer tank inlet pipe (152), a buffer tank outlet pipe (153), a buffer tank heater (154) and a buffer tank airbag (155); The buffer tank body (151) is a closed tank structure, and the buffer tank body (151) is provided with a tank inlet and a tank outlet; the buffer tank inlet pipe (152) is arranged at the tank inlet, one end of the buffer tank inlet pipe (152) is connected to the second pneumatic switch valve (11), and the other end of the buffer tank inlet pipe (152) extends into the interior of the buffer tank body (151); The buffer tank outlet pipe (153) is arranged at the tank outlet, one end of the buffer tank outlet pipe (153) extends into the interior of the buffer tank body (151), and the other end of the buffer tank outlet pipe (153) is connected to the third pneumatic switch valve (13); the buffer tank airbag (155) is arranged inside the buffer tank body (151) and is arranged near the top end of the buffer tank body (151).

6. The dense-phase carbon dioxide supply and storage system according to claim 1, characterized in that The carbon dioxide membrane separator includes a primary separator (24) and a secondary separator (25); The outlet end of the carbon dioxide ejector (21) is connected to the inlet end of the primary separator (24), the first outlet of the primary separator (24) is connected to the inlet end of the secondary separator (25), and the second outlet of the primary separator (24) serves as an impurity gas treatment interface; The first outlet of the secondary separator (25) is connected to the shell side inlet of the heat exchanger (5), and the second outlet of the secondary separator (25) is connected to the inlet end of the primary separator (24).

7. A method for using a dense-phase carbon dioxide supply and storage system according to any one of claims 1-6, characterized in that, Including: Using the carbon dioxide gasification subsystem to store the liquid carbon dioxide supplemented from the outside; Using the carbon dioxide gasification subsystem to perform phase conversion on the stored liquid carbon dioxide to obtain supercritical carbon dioxide; Filling the supercritical carbon dioxide into the supercritical carbon dioxide storage subsystem for storage; Using the supercritical carbon dioxide storage subsystem to provide a carbon dioxide working medium source with stable working conditions for the supercritical carbon dioxide Brayton cycle system; Using the carbon dioxide gas recovery and utilization subsystem to recover, liquefy and reinject the leaked gaseous carbon dioxide in the carbon dioxide gasification subsystem, the supercritical carbon dioxide storage subsystem and the supercritical carbon dioxide Brayton cycle system into the carbon dioxide gasification subsystem.

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