CN108508057B - Low-voltage phase balance experimental device and online sampling and measuring method - Google Patents

Abstract

The invention provides a low-pressure phase balance experiment device and an online sampling measurement method, which can realize phase balance data measurement and online sampling in a low-pressure environment, so that experiments or industrial processes can run continuously without interference, and can be applied to experimental industrial processes such as petroleum, chemistry, and metallurgy, providing accurate fluid phase balance experimental data, and providing basic physical property data for design, operation, control and optimization of process industries.

Description

A low-pressure phase balance experimental device and online sampling measurement method

technical field

The invention relates to the field of experimental data testing in the fields of petroleum, chemical and metallurgical industries, in particular to a low-pressure phase balance experimental device and an online sampling measurement method.

Background technique

The fluid phase equilibrium property is an indispensable basic physical property for the design, operation, control and optimization of industrial processes. It determines the correctness and accuracy of process simulation calculations. For example, in the calculation of separation towers, important parameters such as the theoretical plate number and operating reflux ratio of the distillation column are closely related to the phase equilibrium properties. Moreover, rectification, extraction, absorption, and leaching are the basic unit operations of industrial processes. Any research on them must be based on the phase equilibrium properties of the corresponding system.

Fluid phase equilibrium properties can be obtained by theoretical thermodynamic methods, such as empirical correlation, activity coefficient, state equation and other methods. With the advancement of computational chemistry techniques, predictive models for phase equilibrium properties have also been developed, such as COSMO-RS, COSMO-SAC, etc. However, although the model method can obtain the fluid phase equilibrium properties, it must be based on experimental data, otherwise it is impossible to know whether the model method is correct, and the characteristic parameters in many model methods are obtained by regression experimental data, so it is very important to measure the real phase equilibrium data under different conditions by experimental methods.

The measurement of fluid phase equilibrium properties can be divided into static method, circulation method or isothermal and isobaric equilibrium method according to different experimental methods or data types obtained. Since the development of fluid phase balance, a large amount of experimental data has been published in the literature, including low pressure, normal pressure and high pressure data, especially the data of normal pressure is the most extensive, because the measurement of normal pressure fluid phase balance does not involve pressure balance and control, collection of low pressure samples, etc., and the experiment is carried out directly in the atmospheric environment. For low-pressure systems (that is, the internal pressure of the experimental system is lower than atmospheric pressure), it is necessary to consider how to keep the pressure constant, how to collect samples, and how to minimize external disturbances, etc., and these technical issues directly affect the accuracy of the measurement of fluid phase equilibrium properties.

In experimental work, due to the particularity of the material system, it is often necessary to conduct experimental operations under low pressure. However, no matter in actual industrial production or in laboratory research, samples must be analyzed regularly or under certain conditions, but how to obtain effective samples for analysis in the case of continuous operation of the device is a continuous problem. At present, whether it is in industry or in the laboratory, for samples with a pressure higher than atmospheric pressure, it is generally directly sampled through a sampling bottle, but when the pressure is too high, the sample will flash during sampling, so that the obtained sample cannot represent the original composition. For samples under low pressure, due to the low pressure of the sample to be taken, it cannot directly enter the sampling bottle. Before sampling, the pressure in the sample bottle must be kept not greater than the system pressure, which makes the sampling of low-pressure samples more complicated and requires high sealing.

In order to facilitate the realization of on-line sampling in a low-pressure environment in the low-pressure phase balance experiment, to make the experiment or industrial process run continuously without interference, and to obtain accurate fluid phase balance data, especially the vapor-liquid phase balance data, it is necessary to design a low-pressure phase balance experiment device and an online sampling method.

Contents of the invention

The technical problem to be solved by the present invention is: in order to overcome the deficiencies of the prior art, the present invention provides a low-pressure phase balance experimental device and an online sampling measurement method that can realize phase balance measurement and online sampling in a low-pressure environment, so that experiments or industrial processes can run continuously without interference.

The technical solution adopted by the present invention to solve the technical problem is: a low-pressure phase balance experimental device, including a distillation balance system, a cooling circulation system and an automatic pressure stabilization control system. The distillation balance system is connected to the upper part of the cooling circulation system through a circulation cooler pipeline, and the distillation balance system is connected to the bottom of the cooling circulation system through a liquid return pipeline. The cooling circulation system has a pressure balance conduit. There is a sampling port at the bottom of the cooling circulation system, and the end of the liquid return pipe is connected to the sampling port. The other side of the liquid return pipe corresponding to the sampling port has an online sampling port. The lower side wall of the distillation balance system also has an online sampling port. The online liquid pipe under the tight nut of the liquid pipe, the booster assembly includes a vent port and a booster valve connected to the online sampling pressure line, the vacuum assembly includes a vacuum system and a sampler pressure control valve connected to the online sampling pressure line, and the vacuum system is connected to the lower end of the sampler pressure control valve through a vacuum system interface.

The distillation balance system includes a cylindrical distillation body, the top and side walls of the distillation body are respectively fixed with temperature measuring sleeves, a sample inlet is opened on the circumferential side wall of the distillation body corresponding to the bottom position of the side wall temperature measuring sleeve, a liquid blocking tube is fixed below the temperature measuring sleeve on the top of the distillation body, a liquid spray coil is fixed at the bottom of the temperature measurement sleeve inside the side wall of the distillation body, and a fluid cover is fixed below the liquid spray coil. A distillation sampling port is opened on the top of the boiling chamber corresponding to the side wall of the distillation body. An air induction pipe communicating with the outside is fixed in the boiling chamber of the balancer, and an air induction valve is arranged in the air induction pipe.

The stirring device can be a mechanical stirrer or a magnetic stirrer. A heating system needs to be designed at the bottom of the boiling chamber of the balancer. The heating system can adopt electric heating, water/oil bath jacket heating, and coil heating. The operating temperature range is from room temperature to 120°C, and the preferred temperature range is from room temperature to 90°C. The spray coil height ranges from 40mm to 80mm. The liquid level at which the sample is added must be 10mm to 50mm above the apex of the fluid shield. The outlet of the liquid spray coil is facing the bottom of the temperature measuring sleeve in the side wall of the distillation body. The flow rate of the cooling medium is such that the rate of droplets dripping out through the dropper is not greater than 120 drops per minute.

The pressure stabilization automatic control system includes a controller and a pressure stabilization buffer tank connected to the distillation balance system through a pressure stabilization system interface. The pipeline between the pressure stabilization buffer tank and the pressure stabilization system interface is sequentially connected with a second regulating valve and a solenoid valve. The top of the pressure stabilization buffer tank has a pressure gauge and a vent port. Valve, solenoid valve and vacuum pump, the decompression assembly also includes a ball valve connected in parallel with the first regulating valve; pressure sensors are respectively connected to the pressure measuring port and the pressure stabilizing buffer tank.

The cooling cycle system is a coil condenser, and the circulating cooler is a jacket condenser. The cooling medium of coil condenser and jacket condenser is circulating water, hot water or heat transfer oil.

After a certain amount of experimental sample is added to the distillation equilibrium system through the sample inlet and the system pressure reaches the target value, the sample is heated by electric heating. The heating method can be external heating or internal heating, and stirring is carried out while heating. After the liquid boils, the boiling fluid is ejected from the liquid spray coil under the force of the liquid flow cover, and then the vapor and liquid phases are separated in the liquid resistance tube, the liquid phase returns to the boiling chamber of the balancer to mix with the main body, and the gas phase flows into the cooling circulation system.

Through two online sampling ports and a sampling device connected to the online sampling port, online sampling can be realized, and online sampling of gas and liquid can be carried out separately, so as to realize the continuous operation of vapor-liquid phase equilibrium experiment at different levels of pressure, so that the experiment or industrial process can run continuously without interference.

An online sampling measurement method of a low-pressure phase balance experimental device, comprising the following measurement steps:

A. Check the status of each regulating valve and solenoid valve, confirm that the position and state of each regulating valve and solenoid valve are correct, add about 300ml of experimental samples through the sample port, and close the vacuum valve of the sample port;

B. Close all regulating valves and solenoid valves of the pressure-stabilizing buffer tank, and start the controller at the same time;

C. Turn on the vacuum pump, and slowly open the ball valve after the vacuum pump runs stably;

D. Observe the pressure gauge on the top of the pressure-stabilizing buffer tank. When the value is close to the experimental target value, gradually close the ball valve and open the first regulating valve and the third regulating valve;

E. After the pressure of the pressure-stabilizing buffer tank reaches and stabilizes at the target value, slowly open the second regulating valve to make the pressure of the experimental system reach the target value;

F. After the whole system is stable, slowly heat the boiling chamber of the balancer to gradually increase the temperature of the system;

G. Open the stirring device and the bleed air valve on the bleed pipe while heating;

H. After the liquid in the boiling chamber of the balancer boils, adjust the heating load to keep the system temperature constant, and at the same time observe the reflux rate of the cooling circulation system, and the reflux rate is not greater than 120 drops/min;

I. After the system is stable for 30 minutes, read the temperature and pressure experimental values every 5 minutes, read 10 groups in total, and take the average value;

J. Adjust the target value of the control pressure and measure the next experimental point.

The beneficial effects of the present invention are that the low-pressure phase balance experimental device and online sampling method provided by the present invention can realize online sampling in a low-pressure environment, so that experiments or industrial processes can run continuously without interference, and can be applied to experimental industrial processes such as petroleum, chemistry, and metallurgy, providing accurate fluid phase equilibrium experimental data for them, and providing basic physical property data for design, operation, control and optimization of process industries.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a structural schematic diagram of a distillation equilibrium system and a cooling circulation system of the present invention.

Fig. 2 is a flow chart of the pressure control system of the present invention.

Fig. 3 is a schematic structural view of the sampling device of the present invention.

Fig. 4 is a sectional view of B-B in Fig. 3 .

Fig. 5 is a comparison chart of the saturated vapor pressure of the pure substance measured by the present invention and the literature value.

Fig. 6 is the T-x(y) diagram of the vapor-liquid equilibrium data of the tetrachlorethylene and 1-butanol binary mixture measured in the present invention when the absolute pressure is 6kPa and the phase equilibrium compared with the literature.

Figure 7 is an x-y diagram of the phase equilibrium between the vapor-liquid equilibrium data and the literature comparison of the binary mixture of tetrachlorethylene and 1-butanol at an absolute pressure of 6kPa.

In the figure 1, liquid return pipe 2, pressure balance conduit 3, cooling circulation system 4, circulating cooler 5, pressure measuring port 6, pressure stabilizing system port 7, sampling port 8, online sampling port 9, tight nut of liquid receiving pipe 10, online liquid receiving pipe 11, online sampling pressure line 12, vent port 13, booster valve 14, sampler pressure control valve 15, distillation body 16, temperature measuring sleeve 17, sampling port 18. Liquid blocking pipe 19, liquid spray coil 20, fluid cover 21, balancer boiling chamber 22, stirring device 23, distillation sampling port 24, pressure stabilizing buffer tank 25, second regulating valve 26, solenoid valve 27, pressure gauge 28, vent port 29, pressure source 30, pressure reducing valve 31, third regulating valve 32, first regulating valve 33, vacuum pump 34, ball valve 35, pressure sensor 36 , bleed pipe.

Detailed ways

The present invention is described in further detail now in conjunction with accompanying drawing. These drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, so they only show the configurations related to the present invention.

A low-pressure phase balance experimental device as shown in Figures 1 to 4 is the optimal embodiment of the present invention, including a distillation balance system, a cooling cycle system 3 and an automatic control system for pressure stabilization.

The distillation balance system is communicated with the upper part of the cooling circulation system 3 through the circulating cooler 4 pipelines, and the distillation balance system is connected with the bottom of the cooling circulation system 3 through the liquid return pipe 1 pipeline. The cooling circulation system 3 has a pressure balance conduit 2. The top of the pressure balance conduit 2 protrudes from the top of the cooling circulation system 3 and has a pressure measurement port 5 and a pressure stabilization system interface 6. The pressure stabilization system interface 6 is connected with a pressure stabilization automatic control system; The other side of the sampling port 7 corresponding to the liquid return pipe 1 has an online sampling interface 8, and the lower side wall of the distillation balance system also has an online sampling interface 8, and the online sampling interface 8 is fixedly connected with a sampling device; 10. The pressurization assembly includes a vent port 2812 and a booster valve 13 communicated with the online sampling pressure pipeline 11, and the vacuum assembly includes a vacuum system and a sampler pressure control valve 14 communicated with the online sampling pressure pipeline 11. The vacuum system is connected to the lower end of the sampler pressure control valve 14 through a vacuum system interface.

The cooling circulation system 3 is a coil condenser, and the circulation cooler 4 is a jacket condenser. The cooling medium of coil condenser and jacket condenser is circulating water, hot water or heat transfer oil. The cooling medium can be cold water, warm water or other low-temperature medium according to the different properties of the actual experimental system. The purpose is to cool the vapor phase from the distillation equilibrium system to liquid under the pressure of the system, and return it to the boiling chamber through natural flow. In the cooling circulation system 3, a liquid collector is provided to facilitate sample collection and analysis.

The distillation balance system includes a cylindrical distillation body 15, the top and side walls of the distillation body 15 are respectively fixed with temperature measuring sleeves 16, the circumferential side wall of the distillation body 15 corresponding to the bottom position of the side wall temperature measuring sleeve 16 is provided with a sampling port 17, a liquid blocking tube 18 is fixed below the temperature measuring sleeve 16 in the top of the distillation body 15, and a liquid spray coil 19 is fixed at the bottom of the temperature measuring sleeve 16 in the side wall of the distillation body 15, and a fluid cover 2 is fixed below the liquid spray coil 19 0. There is a balancer boiling chamber 21 between the fluid cover 20 and the bottom of the distillation body 15. There is a stirring device 22 inside the balancer boiling chamber 21. A distillation sampling port 23 is opened on the top of the balancer boiling chamber 21 corresponding to the side wall of the distillation body 15. An air induction pipe 36 communicating with the outside is fixed in the balancer boiling chamber 21, and an air induction valve is arranged in the air induction pipe 36. Stirring device 22 and bleed pipe 36 can eliminate the impact of bumping on the experiment.

The pressure stabilization automatic control system includes a controller and a pressure stabilization buffer tank 24 connected to the distillation balance system through the pressure stabilization system interface 6. The pipeline between the pressure stabilization buffer tank 24 and the pressure stabilization system interface 6 is connected with a second regulator valve 25 and a solenoid valve 26 in sequence. The third regulating valve 31, the third regulating valve 31 is in communication with the pressure stabilizing buffer tank 24 pipelines, and the described decompression assembly includes the first regulating valve 32, solenoid valve 26 and vacuum pump 33 connected in sequence, and the described decompression assembly also includes a ball valve 34 connected in parallel with the first regulating valve 32; the pressure measuring port 5 and the stabilizing buffer tank 24 are respectively connected with a pressure sensor 35.

In a specific experiment or industrial process, the stirring device 22 can be a mechanical stirrer or a magnetic stirrer. A heating system needs to be designed at the bottom of the boiling chamber 21 of the balancer. The heating system can adopt electric heating, water/oil bath jacket heating, and coil heating. The operating temperature range is from room temperature to 180°C, and the preferred temperature range is from room temperature to 150°C. The height range of the spray coil 19 is 40mm to 80mm. The height of the liquid level for adding the sample must be 10 mm to 50 mm higher than the apex of the fluid shield 20 . The outlet of the liquid spray coil 19 is facing the bottom of the temperature measuring sleeve 16 in the side wall of the distillation body 15 . The flow rate of the cooling medium is such that the rate of droplets dripping out through the dropper is not greater than 120 drops per minute.

A certain amount of experimental sample is added to the distillation equilibrium system through the sample inlet 17. After the system pressure reaches the target value, the sample is heated by electric heating. The heating method can be external heating or internal heating, and stirring is performed while heating. After the liquid boils, the boiling fluid is ejected from the liquid spray coil 19 under the force of the liquid flow cover, and then the vapor and liquid phases are separated in the liquid resistance pipe 18, and the liquid phase returns to the balancer boiling chamber 21 to mix with the main body, and the gas phase flows into the cooling circulation system 3.

When sampling, it can be carried out by an online sampling device without interrupting the experimental or industrial process. The online sampling structure is a spherical interface, which is connected to the container to be sampled (sampling port 7 at the bottom of the cooling circulation system 3 or the lower side wall of the distillation balance system). Before connecting, close the sampler pressure control valve 14, vent valve and sampling port 7, and connect the vacuum system interface to the vacuum system at the same time; then slowly open the sampler pressure control valve 14 to make the pressure in the sampling device equal to or slightly lower than the pressure of the container to be sampled (sampling port 7 at the bottom of the cooling cycle system 3 or the lower side wall of the distillation balance system) and keep the pressure constant; open slowly Sampling port 7, so that the sample in the container to be sampled (sampling port 7 at the bottom of the cooling circulation system 3 or the lower side wall of the distillation balance system) slowly flows into the online liquid receiving pipe 10 through the spherical interface, and a solvent can be put into the online liquid receiving pipe 10 in advance to fix the sample. 12 into the protective nitrogen; finally through the sampling port 7 sampling analysis, or take out the online liquid pipe 10 through the fastening nut of the liquid pipe and then further process and analyze the sample.

Preferably, the pressure operating range of the sampling device is from 0.1 kPa to 1 atmosphere, and the temperature operating range of the sampling device is from room temperature to 280°C.

Through the two online sampling interfaces 8 and the sampling device connected to the online sampling interface 8, online sampling can be realized, and the gas and liquid can be sampled online respectively, so as to realize the continuous operation of the vapor-liquid phase equilibrium experiment at different levels of pressure, so that the experiment or industrial process can run continuously without interference.

An on-line sampling measurement method of a low-pressure phase balance experimental device can use the above-mentioned sampling measurement device to sample and use the following measurement steps to conduct experiments.

A, check the state of each regulating valve and solenoid valve 26, after confirming that each regulating valve and solenoid valve 26 are in the correct position state, add about 300ml of experimental sample through the sample inlet 17, and close the sample inlet 17 vacuum valve;

B, close all regulating valves and electromagnetic valve 26 of pressure-stabilizing buffer tank 24, start controller simultaneously;

C. Turn on the vacuum pump 33, and slowly open the ball valve 34 after the vacuum pump 33 runs stably;

D, observe the pressure gauge 27 on the top of the pressure stabilizing buffer tank 24, when the value is close to the experimental target value, gradually close the ball valve 34 and open the first regulating valve 32 and the third regulating valve 31;

E. After the pressure of the pressure-stabilizing buffer tank 24 reaches and stabilizes at the target value, slowly open the second regulating valve 25 to make the pressure of the experimental system reach the target value;

F. After the whole system is stable, slowly heat the boiling chamber 21 of the balancer to gradually increase the temperature of the system;

G, heating open the air-inducing valve on stirring device 22 and air-introducing pipe 36 simultaneously;

H. After the liquid in the boiling chamber 21 of the balancer boils, adjust the heating load to keep the system temperature constant, and observe the reflux rate of the cooling circulation system 3 at the same time, and the reflux rate is not more than 120 drops/min;

I. After the system is stable for 30 minutes, read the temperature and pressure experimental values every 5 minutes, read 10 groups in total, and take the average value;

J. Adjust the target value of the control pressure and measure the next experimental point.

Adopt above-mentioned measurement procedure, can measure the saturated vapor pressure of ethanol and water pure component, and the experimental data measured and literature value comparison result are drawn in Fig. 5, both are consistent, show that the sampling measuring device and measuring method that the present invention provides can be used for the measurement of pure fluid saturated vapor pressure.

Adopt above-mentioned measurement procedure, can measure the vapor-liquid equilibrium of tetrachlorethylene and 1-butanol binary mixture when absolute pressure is 6kPa, and draw the result in Fig. 6, Fig. 7, wherein in Fig. 6 and Fig. 7, compare the T-x (y) figure and x-y figure of phase equilibrium respectively, compare by experimental data and literature value, find that both keep consistent, show that the sampling measuring device and measuring method that the present invention provides can be used for the measurement of mixture vapor-liquid balance.

Inspired by the above-mentioned ideal embodiment according to the present invention, through the above-mentioned description content, relevant workers can make various changes and modifications within the scope of not departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, but must be determined according to the scope of the claims.

Claims (3)

1. A low-pressure phase balance experimental device, characterized in that it includes a distillation balance system, a cooling circulation system (3) and an automatic pressure stabilization system. The distillation balance system and the upper part of the cooling circulation system (3) are connected through a circulating cooler (4) pipeline, and the bottom of the distillation balance system and the cooling circulation system are connected through a liquid return pipe (1). Interface (6), the pressure stabilizing system interface (6) is connected with an automatic voltage stabilizing control system; the bottom of the cooling circulation system (3) has a sampling port (7), the end of the liquid return pipe (1) is connected to the sampling port (7), and the sampling port (7) has an online sampling port (8) corresponding to the other side of the liquid return pipe (1), and the lower side wall of the distillation balance system also has an online sampling port (8), and a sampling device is fixedly connected to the online sampling port (8); Sampling assembly, pressurization assembly and vacuum assembly. The online sampling interface (8) is connected with an online sampling pressure pipeline (11). The sampling assembly includes a liquid connection fastening nut (9) that is sealed and fixedly connected under the online sampling interface (8) and an online liquid connection pipe (10) connected under the liquid connection tight nut (9). The pressurization assembly includes a vent port (12) and a booster valve (13) that communicate with the online sampling pressure pipeline (11). The vacuum assembly includes a vacuum system and the sampler pressure control valve (14) connected with the online sampling pressure line (11), the vacuum system is connected to the lower end of the sampler pressure control valve (14) through the vacuum system interface (15); The distillation balance system includes a cylindrical distillation body (15), the top and side walls of the distillation body (15) are respectively fixed with a temperature measuring sleeve (16), the distillation body (15) is provided with a sample injection port (17) on the circumferential side wall corresponding to the bottom position of the side wall temperature sleeve (16), and a liquid blocking tube (18) is fixed below the temperature measurement sleeve (16) in the top of the distillation body (15), and the temperature measurement sleeve (16) in the side wall of the distillation body (15) A liquid spray coil (19) is fixed at the bottom, and a fluid cover (20) is fixed below the liquid spray coil. Between the fluid cover (20) and the bottom of the distillation body (15) is a balancer boiling chamber (21). The balancer boiling chamber (21) has a stirring device (22). The top of the balancer boiling chamber (21) corresponds to the side wall of the distillation body (15) and has a distillation sampling port (23). A trachea (26), the air-introduction pipe (36) is provided with an air-induction valve; The pressure stabilization automatic control system includes a controller and a pressure stabilization buffer tank (24) connected to the distillation balance system through a pressure stabilization system interface (6). The pipeline between the pressure stabilization buffer tank (24) and the pressure stabilization system interface (6) is sequentially connected with a second regulating valve (25) and a solenoid valve (26). The top of the pressure stabilization buffer tank (24) has a pressure gauge (27) and a vent port (28). The assembly includes a pressure source (29), a pressure reducing valve (30), a solenoid valve (26) and a third regulating valve (31) connected in sequence. The third regulating valve (31) is in pipeline communication with the pressure stabilizing buffer tank (24). The decompression assembly includes a first regulating valve (32), a solenoid valve (26) and a vacuum pump (33) connected in sequence. The decompression assembly also includes a ball valve (34) connected in parallel with the first regulating valve (32); Pressure sensors (35) are respectively connected to them. 2. A low-pressure phase equilibrium experimental device according to claim 1, characterized in that: the cooling circulation system (3) is a coil condenser, and the circulation cooler (4) is a jacket condenser. 3. a kind of on-line sampling measurement method of low-pressure phase balance experimental device, it is characterized in that: adopt a kind of low-voltage phase balance experimental device as claimed in claim 1, comprise following measurement steps: A. Check the status of each regulating valve and solenoid valve (26), confirm that the position and state of each regulating valve and solenoid valve (26) are correct, then add about 300ml of experimental samples through the sampling port (17), and close the vacuum valve of the sampling port (17); B. Close all regulating valves and electromagnetic valves of the pressure-stabilizing buffer tank (24), and start the controller at the same time; C. Turn on the vacuum pump (33), and slowly open the ball valve (34) after the vacuum pump (33) runs stably; D. Observe the pressure gauge (27) on the top of the pressure-stabilizing buffer tank (24). When the value is close to the experimental target value, gradually close the ball valve (34) and open the first regulating valve (32) and the third regulating valve (31); E. After the pressure of the pressure-stabilizing buffer tank (24) reaches and stabilizes at the target value, slowly open the second regulating valve (25) to make the pressure of the experimental system reach the target value; F. After the whole system is stable, slowly heat the boiling chamber (21) of the balancer to gradually increase the temperature of the system; G. Open the stirring device (22) and the bleed air valve on the bleed pipe while heating; H. After the liquid in the boiling chamber (21) of the balancer boils, adjust the heating load to keep the system temperature constant, and observe the reflux rate of the cooling circulation system (3) at the same time, and the reflux rate is not greater than 120 drops/min; I. After the system is stable for 30 minutes, read the temperature and pressure experimental values every 5 minutes, read 10 groups in total, and take the average value; J. Adjust the target value of the control pressure and measure the next experimental point.