Experimental device and method for observing dynamic characteristics of supercritical carbon dioxide system using fuel gas

Abstract

The present invention relates to an experimental apparatus and method for observing the dynamic characteristics of a gas-supercritical CO2 system. By performing heat exchange between a high-temperature air flow and an intermediate medium flow in a first heat exchanger, heat exchange between the intermediate medium flow and a medium-temperature supercritical CO2 working medium flow in a second heat exchanger, and heat exchange between room-temperature and medium-temperature supercritical CO2 working medium flows in a third heat exchanger, the apparatus solves the problem of accurately measuring the dynamic characteristics of the heat exchange process during the rapid load changes involved in flexible peak regulation in a gas-supercritical CO2 thermodynamic cycle. The apparatus achieves reliable control and precise measurement of the heat exchange process between gas waste heat and supercritical CO2, providing an experimental means for validating transient characteristic models of the heat exchange process and thereby promoting research into the coordinated operation mechanism of the gas-supercritical CO2 thermodynamic cycle.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-supercritical CO2 thermodynamic cycle, in particular to an experimental device and method for observing dynamic characteristics of a gas-supercritical carbon dioxide system. Background Art

[0002] The rapid load-scaling operation of a gas-to-supercritical CO2 thermal cycle power generation system can alleviate the peak load regulation pressure of coal-fired power generation units in the power grid. In this system, a gas-to-supercritical CO2 heat exchanger is used to heat the supercritical CO2 with waste heat from the gas, ensuring that the supercritical CO2 meets the requirements of a supercritical turbine cycle working fluid. However, due to the significantly lower heat flux density of the gas than that of the supercritical CO2, and the presence of heat transfer-flow coupling within the gas-to-supercritical CO2 heat exchanger, the dynamic characteristics of the heat exchange process are difficult to observe, making reliable control of the gas-to-supercritical CO2 heat exchange difficult. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the present invention provides an experimental device and method for observing the dynamic characteristics of a gas-supercritical carbon dioxide system, the purpose of which is to realize the observation of the dynamic characteristics of the gas-supercritical CO2 coupled heat exchange process.

[0004] The technical solution adopted in the present invention is as follows:

[0005] An experimental device for observing dynamic characteristics of gas-supercritical CO2 coupling process, comprising:

[0006] The first heat exchanger uses hot air provided by a hot air gun to heat the intermediate heat transfer medium output from the second heat exchanger, and the heated intermediate heat transfer medium is input into the second heat exchanger. A thermometer is provided on the pipe connecting the intermediate heat transfer medium outlet of the first heat exchanger and the intermediate heat transfer medium inlet of the second heat exchanger;

[0007] The second heat exchanger uses the heated intermediate heat transfer medium output from the first heat exchanger to heat the medium-temperature supercritical CO2 output from the third heat exchanger. The heated medium-temperature supercritical CO2 is input into the third heat exchanger to form a carbon dioxide circulation loop. A first pressure regulating valve is provided on the pipeline connecting the medium-temperature supercritical CO2 outlet of the second heat exchanger and the medium-temperature supercritical CO2 inlet of the third heat exchanger. The cooled intermediate heat transfer medium is input into the first heat exchanger for reheating to form an intermediate heat transfer medium loop. A fluid pump is provided on the pipeline connecting the intermediate heat transfer medium outlet of the second heat exchanger and the intermediate heat transfer medium inlet of the first heat exchanger.

[0008] The third heat exchanger utilizes the medium-temperature supercritical CO2 output from the second heat exchanger to exchange heat with the room-temperature supercritical CO2, heating the room-temperature supercritical CO2 into medium-temperature supercritical CO2 and inputting it into the second heat exchanger. After releasing heat, the medium-temperature supercritical CO2 is output from the third heat exchanger as carbon dioxide exhaust gas, and a second pressure regulating valve is provided on the output pipeline;

[0009] A working fluid pump is used to pressurize CO2 to form room-temperature supercritical CO2 and transport it to the third heat exchanger for heat exchange with medium-temperature supercritical CO2;

[0010] A differential pressure transmitter is used to measure the pressure difference before and after the hot air flows through the first heat exchanger;

[0011] a thermocouple, used to measure the temperature of the hot air before and after it passes through the first heat exchanger;

[0012] Flowmeter, used to measure the flow rate of hot air, and the temperature of the fluid pump outlet and the working medium pump outlet;

[0013] Thermometer, used to measure the temperature of CO2 entering and leaving each heat exchanger and the temperature of the intermediate heat transfer medium;

[0014] The control module is connected to the signal output ends of the differential pressure transmitter, thermocouple, flow meter and thermometer, and is connected to the signal input ends of the fluid pump, hot air gun and various valves.

[0015] Further technical solutions are:

[0016] The intermediate heat conducting medium is DOWTHERM A.

[0017] The structure of the first heat exchanger includes an air duct and a coil device arranged in the air duct. The input end of the air duct is connected to the output end of the hot air gun to use high-temperature air to simulate gas. The intermediate heat transfer medium flows through the coil device.

[0018] The second heat exchanger and the third heat exchanger are both printed circuit board type heat exchangers.

[0019] The working fluid pump is an SFC-24 supercritical fluid pump.

[0020] A method for observing dynamic characteristics of a gas-supercritical CO2 coupling process, using a gas-supercritical CO2 coupling process observation dynamic characteristics experimental device, comprising:

[0021] Start the fluid pump to fill the intermediate heat-conducting medium loop with the intermediate heat-conducting medium, and the intermediate heat-conducting medium begins to circulate in the device loop;

[0022] The temperature and flow rate of the outlet air of the hot air gun are controlled by a control system to fluctuate intermittently, so that the hot air and the intermediate heat transfer medium exchange heat in the first heat exchanger;

[0023] The working fluid pump is started to compress the room-temperature carbon dioxide to a supercritical state, forming room-temperature supercritical CO2, which is then transported to the third heat exchanger. After absorbing heat in the third heat exchanger, the medium-temperature supercritical CO2 is formed and transported to the second heat exchanger to exchange heat with the intermediate heat transfer medium. The pressure of the supercritical CO2 in the carbon dioxide circulation loop is adjusted by the first pressure regulating valve, and the pressure of the carbon dioxide exhaust gas is controlled by the second pressure regulating valve.

[0024] Record the parameters of the heat exchange process collected by differential pressure transmitters, thermocouples, flow meters, and thermometers.

[0025] As a further improvement of the above technical solution:

[0026] Also included: Conducting CO2 pseudo-critical region characteristic experiments:

[0027] The working fluid pump and the first pressure regulating valve are adjusted to control the supercritical carbon dioxide to approach and pass through the pseudo-critical region at different control rates, and the parameters of the heat exchange process collected by the differential pressure transmitter, thermocouple, flow meter, and thermometer are recorded.

[0028] By analyzing the parameters collected during the heat exchange process, the changing relationship between the independent variable parameters and the dependent variable parameters is established to complete the dynamic characteristic observation.

[0029] The beneficial effects of the present invention are as follows:

[0030] The present invention solves the problem of the difficulty in accurately measuring the dynamic characteristics of the heat exchange process during the flexible peak regulation process of the gas-supercritical CO2 thermodynamic cycle with rapid load changes. Using a gas-intermediate heat transfer medium-supercritical CO2 heat exchange system, the heat source of both systems is the waste heat of gas, and the cold source is supercritical CO2. By observing the dynamic characteristics of the gas-intermediate heat transfer medium-supercritical CO2 heat exchange system, the results obtained can accurately reflect the dynamic characteristics of the heat exchange between gas and supercritical CO2. That is, the results can reflect the dynamic characteristics of the gas-supercritical CO2 heat exchange system, and the system can be reliably controlled in practical applications based on the dynamic characteristics.

[0031] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the structure of the experimental device of an embodiment of the present invention.

[0033] In the figure: 1. Hot air gun; 2. First heat exchanger; 3. Pitot tube flowmeter; 4. Fluid pump; 6. Working fluid pump; 7. Third heat exchanger; 8. Second heat exchanger; 9. First pressure regulating valve; 10. Second pressure regulating valve; 11. Computer workstation. DETAILED DESCRIPTION

[0034] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0035] like Figure 1 As shown, the experimental device for observing dynamic characteristics of the gas-supercritical CO2 coupling process of this embodiment includes:

[0036] The first heat exchanger 2 uses hot air provided by the hot air gun 1 to heat the intermediate heat-conducting medium output from the second heat exchanger 8. The heated intermediate heat-conducting medium is input into the second heat exchanger 8. A thermometer is provided on the pipe connecting the intermediate heat-conducting medium outlet of the first heat exchanger 2 and the intermediate heat-conducting medium inlet of the second heat exchanger 8.

[0037] The second heat exchanger 8 uses the heated intermediate heat transfer medium output from the first heat exchanger 2 to heat the medium-temperature supercritical CO2 output from the third heat exchanger 7. The heated medium-temperature supercritical CO2 is input into the third heat exchanger 7 to form a carbon dioxide circulation loop. A first pressure regulating valve 9 is provided on the pipeline connecting the medium-temperature supercritical CO2 outlet of the second heat exchanger 8 and the medium-temperature supercritical CO2 inlet of the third heat exchanger 7. The cooled intermediate heat transfer medium is input into the first heat exchanger 2 for reheating to form an intermediate heat transfer medium loop. A fluid pump 4 is provided on the pipeline connecting the intermediate heat transfer medium outlet of the second heat exchanger 8 and the intermediate heat transfer medium inlet of the first heat exchanger 2.

[0038] The third heat exchanger 7 uses the medium-temperature supercritical CO2 output from the second heat exchanger 8 to exchange heat with the room-temperature supercritical CO2, heating the room-temperature supercritical CO2 into medium-temperature supercritical CO2 and inputting it into the second heat exchanger 8. After releasing heat, the medium-temperature supercritical CO2 is output from the third heat exchanger 7 as exhaust carbon dioxide gas, and a second pressure regulating valve 10 is provided on the output pipeline;

[0039] The working fluid pump 6 is used to pressurize CO2 to form room-temperature supercritical CO2 and transport it to the third heat exchanger 7 for heat exchange with the medium-temperature supercritical CO2;

[0040] A differential pressure transmitter is used to measure the pressure difference before and after the hot air flows through the first heat exchanger 2;

[0041] A thermocouple, used to measure the temperature of the hot air before and after it passes through the first heat exchanger 2;

[0042] Flow meters, including a Pitot tube flow meter 3 for measuring the hot air flow rate, and flow meters for measuring the flow rates at the outlet of the fluid pump 4 and the outlet of the working medium pump 6;

[0043] Thermometer, used to measure the temperature of CO2 entering and leaving each heat exchanger and the temperature of the intermediate heat transfer medium;

[0044] The control module is connected to the signal output terminals of the differential pressure transmitter, thermocouple, flow meter, and thermometer, and is connected to the signal input terminals of the fluid pump 4, the hot air gun 1, and each valve.

[0045] Figure 1 The dashed lines represent signal connection lines, and the solid lines represent working fluid connection pipelines.

[0046] Specifically, the control module is installed on the computer workstation 11 .

[0047] Specifically, the intermediate heat conducting medium is DOWTHERM A.

[0048] Specifically, the structure of the first heat exchanger 2 includes an air duct and a coil device arranged in the air duct. The input end of the air duct is connected to the output end of the hot air gun 1 to use high-temperature air to simulate gas, and the intermediate heat transfer medium flows through the coil device.

[0049] Specifically, the second heat exchanger 8 and the third heat exchanger 7 are both printed circuit board type heat exchangers.

[0050] Specifically, the working fluid pump 6 is an SFC-24 supercritical fluid pump.

[0051] The main function of the hot air gun is to generate hot air to simulate combustion gas with waste heat. It can be programmed and remotely controlled using a computer. The computer controls the temperature and flow of the hot air at the hot air gun outlet to simulate uncertain, transient intermittent disturbances. The main function of the fluid pump is to provide circulation power for the intermediate heat transfer medium and to perform bypass control of the intermediate medium flow. The main functions of the working fluid pump and the pressure regulating valve are to adjust the carbon dioxide parameters respectively to meet the requirements of the dynamic characteristics experiment of heterogeneous energy flow. The main functions of the differential pressure transmitter, thermocouple, flow meter, and thermometer are to measure the thermal parameters during the heat exchange process. The main function of the computer workstation 11 is to communicate with the LABVIEW experimental monitoring platform and issue control instructions to the hot air gun.

[0052] The method for observing the dynamic characteristics of the gas-supercritical CO2 coupling process of this embodiment uses the experimental device for observing the dynamic characteristics of the gas-supercritical CO2 coupling process, including:

[0053] Start the fluid pump 4 to fill the intermediate heat-conducting medium circuit with the intermediate heat-conducting medium, and the intermediate heat-conducting medium begins to circulate in the device circuit;

[0054] The temperature and flow rate of the outlet air of the hot air gun 1 are controlled by the control system to fluctuate intermittently, so that the hot air and the intermediate heat transfer medium exchange heat in the first heat exchanger 2;

[0055] The working fluid pump 6 is started to compress the room-temperature carbon dioxide to a supercritical state, forming room-temperature supercritical CO2, which is then transported to the third heat exchanger 7. After absorbing heat in the third heat exchanger 7, the medium-temperature supercritical CO2 is formed and transported to the second heat exchanger 8 to exchange heat with the intermediate heat transfer medium. The pressure of the supercritical carbon dioxide in the carbon dioxide circulation loop is adjusted by the first pressure regulating valve 9, and the pressure of the carbon dioxide exhaust gas is controlled by the second pressure regulating valve 10.

[0056] Record the parameters of the heat exchange process collected by the differential pressure transmitter, thermocouple, flow meter, and thermometer. By analyzing the collected parameters of the heat exchange process, establish the change relationship between the independent variable parameters and the dependent variable parameters to complete the dynamic characteristic observation.

[0057] The observation method of this embodiment uses a hot air gun with programmable and remote control functions. The temperature and flow rate of the air at the outlet of the hot air gun 1 are controlled by the control system to simulate intermittent disturbances with flexible peak regulation uncertainty and transient mutations.

[0058] The fluid pump 4 provides circulation power for the intermediate heat-conducting medium and performs bypass control of the flow rate of the intermediate heat-conducting medium.

[0059] The method for observing the dynamic characteristics of the gas-supercritical CO2 coupling process of this embodiment further includes: conducting a carbon dioxide pseudo-critical region characteristic experiment:

[0060] The working fluid pump 6 and the first pressure regulating valve 9 are adjusted to control the supercritical carbon dioxide to approach and pass through the pseudo-critical region at different control rates, and the parameters of the heat exchange process collected by the differential pressure transmitter, thermocouple, flow meter and thermometer are recorded.

[0061] The working fluid pump 6 and first pressure regulating valve 9 adjust the CO2 parameters, controlling the supercritical CO2 to approach and pass through the pseudo-critical region at different control rates, thus achieving the parameter changes required for the dynamic characteristics experiment of heterogeneous energy flow. By analyzing the parameters collected during the heat exchange process, the changing relationship between the independent and dependent variables is established to complete the dynamic characteristics observation.

[0062] In summary, this embodiment performs heat exchange between a high-temperature air flow and an intermediate medium flow in a first heat exchanger, heat exchange between the intermediate medium flow and a medium-temperature supercritical CO2 working medium flow in a second heat exchanger, and heat exchange between a room-temperature and medium-temperature supercritical CO2 working medium flow in a third heat exchanger. By using a high-temperature air flow to simulate gas and an intermediate heat transfer medium for intermediate heat exchange, this embodiment solves the problem of accurately measuring the dynamic characteristics of the heat exchange process during the rapid load variation and flexible peak regulation of the gas-supercritical CO2 thermodynamic cycle. This achieves reliable control and precise measurement of the heat exchange process between gas waste heat and supercritical CO2, providing an experimental means for validating transient characteristic models of the heat exchange process and promoting research on the coordinated operation mechanism of the gas-supercritical CO2 thermodynamic cycle.

[0063] Those skilled in the art will understand that the foregoing descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will be able to modify the technical solutions described in the foregoing embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for observing the dynamic characteristics of a gas-supercritical CO2 coupling process, characterized in that: The experimental device for observing dynamic characteristics of gas-supercritical CO2 coupling process includes: The first heat exchanger (2) uses hot air provided by a hot air gun (1) to heat the intermediate heat-conducting medium output from the second heat exchanger (8), and the heated intermediate heat-conducting medium is input into the second heat exchanger (8). A thermometer is provided on a pipe connecting the intermediate heat-conducting medium outlet of the first heat exchanger (2) and the intermediate heat-conducting medium inlet of the second heat exchanger (8); The second heat exchanger (8) uses the heated intermediate heat-conducting medium output from the first heat exchanger (2) to heat the medium-temperature supercritical CO2 output from the third heat exchanger (7), and the heated medium-temperature supercritical CO2 is input into the third heat exchanger (7) to form a carbon dioxide circulation loop, and a first pressure regulating valve (9) is provided on the pipeline connecting the medium-temperature supercritical CO2 outlet of the second heat exchanger (8) and the medium-temperature supercritical CO2 inlet of the third heat exchanger (7), and the cooled intermediate heat-conducting medium is input into the first heat exchanger (2) for reheating to form an intermediate heat-conducting medium loop, and a fluid pump (4) is provided on the pipeline connecting the intermediate heat-conducting medium outlet of the second heat exchanger (8) and the intermediate heat-conducting medium inlet of the first heat exchanger (2); The third heat exchanger (7) utilizes the medium-temperature supercritical CO2 output from the second heat exchanger (8) to exchange heat with the normal-temperature supercritical CO2, heats the normal-temperature supercritical CO2 into medium-temperature supercritical CO2, and inputs the medium-temperature supercritical CO2 into the second heat exchanger (8). After releasing heat, the medium-temperature supercritical CO2 is output from the third heat exchanger (7) as carbon dioxide exhaust gas, and a second pressure regulating valve (10) is provided on the output pipeline. A working fluid pump (6) is used to pressurize CO2 to form room-temperature supercritical CO2 and transport it to the third heat exchanger (7) for heat exchange with the medium-temperature supercritical CO2; A differential pressure transmitter for measuring the pressure difference between the hot air before and after it flows through the first heat exchanger (2); A thermocouple for measuring the temperature of the hot air before and after it passes through the first heat exchanger (2); A flow meter for measuring the flow rate of hot air and the temperature of the outlet of the fluid pump (4) and the outlet of the working medium pump (6); Thermometer, used to measure the temperature of CO2 entering and leaving each heat exchanger and the temperature of the intermediate heat transfer medium; A control module connected to the signal output terminals of the differential pressure transmitter, thermocouple, flow meter, and thermometer, and connected to the signal input terminals of the fluid pump (4), hot air gun (1), and each valve; The observation method includes: Starting the fluid pump (4) to fill the intermediate heat-conducting medium circuit with the intermediate heat-conducting medium, so that the intermediate heat-conducting medium begins to circulate in the device circuit; The temperature and flow rate of the outlet air of the hot air gun (1) are controlled by a control system to fluctuate intermittently, so that the hot air and the intermediate heat-conducting medium exchange heat in the first heat exchanger (2); The working fluid pump (6) is started to compress the normal temperature carbon dioxide to a supercritical state, forming normal temperature supercritical CO2 which is transported to the third heat exchanger (7). After absorbing heat in the third heat exchanger (7), the medium temperature supercritical CO2 is formed and transported to the second heat exchanger (8) to exchange heat with the intermediate heat transfer medium. The pressure of the supercritical carbon dioxide in the carbon dioxide circulation loop is adjusted by the first pressure regulating valve (9), and the pressure of the carbon dioxide exhaust gas is controlled by the second pressure regulating valve (10); Record the parameters of the heat exchange process collected by differential pressure transmitters, thermocouples, flow meters, and thermometers.

2. The observation method according to claim 1, characterized in that The intermediate heat conducting medium is DOWTHERM A.

3. The observation method according to claim 1, wherein: The structure of the first heat exchanger (2) includes an air duct and a coil device arranged in the air duct, the air duct input end is connected to the output end of the hot air gun (1) to utilize high-temperature air to simulate the gas, and the intermediate heat transfer medium flows through the coil device.

4. The observation method according to claim 1, wherein: The second heat exchanger (8) and the third heat exchanger (7) are both printed circuit board type heat exchangers.

5. The observation method according to claim 1, characterized in that: The working fluid pump (6) is an SFC-24 supercritical fluid pump.

6. The observation method according to claim 1, characterized in that: Also includes: Conducting CO2 pseudo-critical region characteristic experiments: The working fluid pump (6) and the first pressure regulating valve (9) are adjusted to control the supercritical carbon dioxide to approach and pass through the pseudo-critical region at different control rates, and the parameters in the heat exchange process collected by the differential pressure transmitter, thermocouple, flow meter, and thermometer are recorded.

7. The observation method according to claim 1 or 6, characterized in that: By analyzing the parameters collected during the heat exchange process, the changing relationship between the independent variable parameters and the dependent variable parameters is established to complete the dynamic characteristic observation.

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