System and method for measuring phase state characteristics of mixed gas

Abstract

The invention discloses a system for measuring the phase state characteristics of mixed gas, and the system comprises a temperature control system which is arranged in a vacuum container and is used for controlling the temperature in a balance kettle to keep constant and displaying the temperature of the wall surface of a constant-temperature bath; the gas storage system is used for storing gas to be tested and supplying three kinds of gas to be tested; the buffer system is used for ensuring the stability of the pressure in the balance kettle; the gas phase balance system is connected with the balance kettle through a gas inlet circulation pipeline and used for bearing a mixture to be measured and keeping the mixture balanced, and the invention further discloses a method for measuring the phase state characteristics of the mixed gas. The temperature sensor, the pressure sensor and the differential pressure sensor which are high in precision are used for measuring phase balance temperature and pressure, the constant temperature device with the high temperature upper limit is used for controlling the temperature, the problems that in the prior art, precision is low, and the applicable temperature upper limit is low are solved, and high-precision ternary mixed gas phase state characteristic measurement is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of phase equilibrium testing, and specifically relates to a system and method for measuring the characteristics of a mixed gas phase. Background Art

[0002] Petroleum is one of the main energy sources in the world today and will still hold a leading position in the coming period. However, with the decreasing reserves and tight supply of conventional petroleum resources, the exploitation of heavy oil has attracted increasing attention. The multi-component thermal fluid thermal recovery technology can effectively supplement the formation energy, thereby effectively improving the exploitation effect and enhancing the recovery rate. Multi-component thermal fluid refers to using gases such as steam, CO 2 , N 2 etc. to replace single steam for oil displacement. Injecting multi-component thermal fluid is the main method to improve the recovery rate of heavy oil, and its gas-phase characteristics are the basis for studying the theory related to heavy oil - mixed gas. The vapor-liquid equilibrium (VLE) data includes temperature T, pressure p, and gas-phase components y. Experiments are the most direct and reliable method to obtain the phase equilibrium data of mixtures, and are also the basis for theoretical research on phase equilibrium, and can test the results of theoretical research.

[0003] There are usually three phase equilibrium testing methods as follows:

[0004] (1) Distillation method: The gas and liquid phases are put into a distillation kettle and heated and vaporized under a constant pressure. The continuously generated steam enters a condenser, and the condensed liquid is placed in different product tanks according to different components. For example, a binary vapor-liquid equilibrium testing system and method with the application number 202310169896.5 fixes the top of the equilibrium kettle on the cold head of a low-temperature refrigerator to provide cold energy to the equilibrium kettle by using the cold head, so as to solve the problem of the high lower limit of temperature measurement of the existing measurement platform, that is, the vapor-liquid equilibrium data of a binary mixture at different equilibrium temperatures and equilibrium pressures within the range of 14K to room temperature can be measured; at the same time, the temperature in the equilibrium kettle is finely adjusted by using the first heater and the second heater to make the difference between the first thermometer and the second thermometer less than a preset difference. Compared with the scheme using low-temperature liquid as the cold source, continuous temperature control can be achieved.

[0005] (2) Gas-liquid double circulation: In the gas-liquid double circulation system, the gas phase in the equilibrium kettle continuously exits the equilibrium kettle under the action of the circulation pump, runs along the pipeline, and finally returns to the liquid phase of the equilibrium kettle. At the same time, the liquid phase in the equilibrium kettle also continuously exits the equilibrium kettle, runs along the pipeline, and returns to the gas phase of the equilibrium kettle. Then, the two phases are mixed to complete heat and mass transfer and reach an equilibrium state. For example, the high-temperature and high-pressure gas-liquid equilibrium test device and method with the application number 201710970747.3 includes an equilibrium kettle, a condenser, and a buffer tank. A gas phase outlet is provided at the top of the equilibrium kettle, which is connected to the inlet of the condenser. The outlet of the condenser is connected to the buffer tank. A liquid phase outlet is provided at the bottom of the equilibrium kettle, and a liquid phase inlet is provided at the top of the equilibrium kettle. A liquid phase sampling pipe is provided between the liquid phase outlet and the liquid phase inlet, and a liquid phase sampling port is provided on the liquid phase sampling pipe. A gas phase inlet is provided at the bottom of the equilibrium kettle, and a gas phase sampling pipe is provided between the gas phase inlet and the inlet of the condenser, and a gas phase sampling port is provided on the gas phase sampling pipe. This relieves the technical problem that the existing gas-liquid equilibrium test device cannot meet the requirement of measuring gas-liquid equilibrium data under high temperature and high pressure, and achieves the technical effect of being able to measure gas-liquid equilibrium data within a wide range of temperatures and pressures by using gas-liquid double circulation and ensuring the accuracy of the data.

[0006] (3) Gas-liquid single and double circulation: In the gas single circulation system, the gas phase in the equilibrium kettle continuously exits the equilibrium kettle under the action of the circulation pump, runs along the pipeline, and finally returns to the liquid phase of the equilibrium kettle. The two phases are continuously mixed to complete heat and mass transfer and quickly reach an equilibrium state. For example, the vapor-liquid equilibrium device and the analysis method of HF in fluorohydrocarbons with the application number 202110901647.1; it includes a phase equilibrium kettle, a heat preservation system, a vapor phase sampling system, a liquid phase sampling system, a cold preservation system, an analysis system, and a vapor phase equilibrium pipe. By using the vapor-liquid equilibrium device for measuring fluorohydrocarbons containing hydrogen fluoride of the present invention, convenient analysis, improved automation degree, and a significant increase in the speed of analyzing samples can be achieved.

[0007] However, the existing phase equilibrium test technologies mostly focus on the phase equilibrium test of binary mixed gases, unable to achieve the phase equilibrium test of ternary mixed gases, and having the defects of low precision and low upper limit of applicable temperature. Summary of the Invention

[0008] The purpose of the present invention is to overcome the defects of the existing technology and provide a system and method for measuring the characteristics of a mixed gas phase state.

[0009] To achieve the above purpose, the present invention adopts the following technical solutions:

[0010] In the first aspect, a system for measuring the characteristics of a mixed gas phase state includes:

[0011] A temperature control system, which is arranged in a vacuum container and is used to control the temperature in the equilibrium kettle to be constant and display the temperature of the constant temperature bath wall surface;

[0012] A gas storage system for storing gases to be tested and realizing the supply of three gases to be tested;

[0013] A buffer system is provided between the equilibrium kettle and the gas storage system to ensure the stability of the pressure in the equilibrium kettle;

[0014] A gas phase equilibrium system is connected to the equilibrium kettle through an intake air circulation pipeline, for carrying the mixture to be tested and keeping it in equilibrium.

[0015] Preferably, it further includes a magnetic stirring system for stirring the gas in the equilibrium kettle to accelerate phase equilibrium.

[0016] Preferably, it further includes a data acquisition system for measuring the temperature, pressure and gas phase composition of the mixed system through a temperature sensor, a pressure sensor and a gas chromatograph.

[0017] Preferably, the temperature sensor is a pt25 platinum resistance thermometer.

[0018] Preferably, the pressure sensor is a Mensor CPT6010 absolute pressure sensor or a GE UNIK5000 differential pressure sensor.

[0019] Preferably, the water vapor storage system includes a water tank and a heater.

[0020] Preferably, the heater is a constant temperature system with a temperature upper limit of 160 °C or above.

[0021] Preferably, a constant temperature bath system is provided in the equilibrium kettle, and there are two symmetric visual windows on it.

[0022] Preferably, the constant temperature bath system has a volume of 6.5 L, is made of stainless steel, and is coated with aluminized polyester film on the outside.

[0023] In a second aspect, a method for measuring the characteristics of a mixed gas phase state includes the following steps:

[0024] S1 System assembly and leak detection: Connect the components of the system, perform vacuum leak detection on the system, and then perform pressure leak detection. If there is a leakage, check for the leakage point;

[0025] S2 Filling of the working medium to be tested: Fill the mixed gas into the equilibrium kettle;

[0026] S3 Temperature control: Adjust the power of the electric heater to maintain a constant temperature until the system reaches stability;

[0027] S4 Data Acquisition: Obtain the peak areas and heights of various substances in the mixed gas on the chromatographic column, and calibrate the gas chromatograph with the prepared standard gas to obtain the gas-phase mole fraction of the mixed gas.

[0028] Preferably, in step S1, for vacuum leak detection, it includes: evacuating the system, then leaving it for a period of time, and observing the change in the reading of the pressure sensor; if the reading of the pressure sensor does not change for a long time, it indicates that the tightness of the system is good in the vacuum state; if the reading of the pressure sensor continues to rise and finally reaches 0.1 MPa, it indicates that the system leaks, and leak point inspection is carried out.

[0029] Preferably, in step S1, for positive-pressure leak detection, it includes: applying a positive pressure of 1.5 MPa, observing the pressure sensor, and after leaving the system for a long time, observing whether the reading decreases. If the reading is gradually decreasing, it proves that there is a leak in the experimental system, and leak point inspection is carried out.

[0030] Preferably, in step S1, leak point inspection includes:

[0031] (1) First, check whether the equilibrium kettle leaks; close the second valve, open the first valve and the third valve for vacuum pumping or pressurization operations. After vacuum pumping or pressurization, leave it for a long time and observe the change in the readings of the two pressure sensors. If the readings do not change, it indicates that there is no leakage inside the equilibrium kettle, and the leak point is in the buffer tank; if the readings change significantly, the equilibrium kettle leaks and needs to be disassembled for repair;

[0032] (2) After ensuring that the equilibrium kettle does not leak, then check whether the buffer tank leaks; open the first valve, the second valve, and the third valve, pressurize the system to 1.5 MPa, and apply soap bubbles to the 3 soldered joints to see if there are slow bubbles emerging. If leakage is found, fill the leak point with solder, and then repeatedly pressurize for leak detection. If the leakage of the three solder joints cannot be observed with soap bubbles and the reading of the pressure sensor always decreases, consider replacing the PTFE gasket connecting the pressure sensor.

[0033] Preferably, in step S2, first evacuate the system, and then connect the system: directly connect the working medium tank to the equilibrium kettle, directly connect the high-pressure nitrogen cylinder to the buffer tank, and connect pressure sensors to both the equilibrium kettle and the buffer tank.

[0034] Preferably, in step S2, the filling of the working medium to be measured includes:

[0035] S21 After connecting the system, close the first valve and the second valve, slowly open the working medium tank for purging to exhaust the residual air in the rubber tube; after purging is completed, connect it to the first valve. At this time, there is a certain amount of residual working medium in the rubber tube;

[0036] Slowly open Valve 1 to allow the working fluid in the rubber tube to slowly enter the equilibrium kettle, and at the same time observe the readings of the pressure sensor and differential pressure sensor; since the equilibrium kettle is currently in a vacuum state, the intake speed is extremely fast, so special attention should be paid to the change in the reading of the differential pressure sensor during this process. When the voltage signal output by the differential pressure sensor reaches 4 - 5V, immediately close Valve 1;

[0037] Slowly open Valve 2 to add N2 to the buffer tank, and observe the reading of the differential pressure sensor. When the voltage signal of the differential pressure sensor drops to about 1.03V, close Valve 2;

[0038] Slowly open Valve 1, pay special attention to the reading of the differential pressure sensor, and fill all the residual gas in the rubber tube into the equilibrium kettle. If the reading of the differential pressure sensor is less than 4V at this time, slowly open the valve of the working fluid tank to fill the working fluid. After the reading reaches 4V, close Valve 1 and the valve of the working fluid tank;

[0039] Repeat steps S23 and S24 until the reading of the pressure sensor reaches the pressure value required for the experiment.

[0040] Preferably, in step S3, the power of the electric heater is adjusted by PID programming to maintain a constant temperature.

[0041] Preferably, in step S3, the PID control process is as follows: first, calculate the error based on the feedback temperature and the desired temperature, then perform calculations for the proportional, integral, and derivative terms based on this error value, and finally sum up the calculated proportional, integral, and derivative terms to obtain the controlled temperature.

[0042] Preferably, in step S1, the conditions for the system to reach stability are: the temperature reaches the set value for more than 40 minutes, and the temperature fluctuation is less than 3mK, and the pressure fluctuation is less than 200Pa.

[0043] Preferably, in step S4, first, use a gas chromatograph to obtain the peak areas and heights of various substances on the chromatographic column. Then, use a high-precision electronic analytical balance to prepare a standard gas by the weighing method, and use the prepared standard gas to calibrate the gas chromatograph to obtain the accurate gas phase mole fraction.

[0044] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:

[0045] In the present invention, high-precision temperature sensors, pressure sensors, and differential pressure sensors are used to measure the phase equilibrium temperature and pressure, and a constant temperature device with a relatively high temperature upper limit is used to control the temperature, which solves the problems of low precision and low applicable temperature upper limit in the prior art, and realizes the measurement of the phase state characteristics of a ternary mixed gas with high precision. Description of the Drawings

[0046] Figure 1 is the overall structural schematic diagram of a system for measuring the characteristics of a mixed gas phase according to the present invention;

[0047] Figure 2 is the connection schematic diagram of the working fluid tank of the ternary premixing device in a system for measuring the characteristics of a mixed gas phase according to the present invention;

[0048] Figure 3 is the connection schematic diagram of the vacuum pumping / pressurizing system in a system for measuring the characteristics of a mixed gas phase according to the present invention;

[0049] Figure 4 is the comparison diagram of experimental data and REFPROP 10.0 calculation data in a method for measuring the characteristics of a mixed gas phase according to the present invention.

[0050] Reference numerals: 1, working fluid tank; 2, refrigeration unit; 3, electric heating controller; 4, temperature and pressure indicator; 5, gas chromatograph; 6, first motor; 7, second motor; 8, vacuum pump; 9, vacuum container; 10, cooling coil; 11, constant temperature bath; 12, electric heater; 13, equilibrium kettle; 14, magnetic stirrer; 15, pressure transmitter; 16, first buffer tank; 17, second buffer tank; 18, water vapor generator. Detailed implementation manners

[0051] The following further describes the detailed implementation manners of a system and method for measuring the characteristics of a mixed gas phase according to the present invention in conjunction with the attached Figures 1-4 , etc. The system and method for measuring the characteristics of a mixed gas phase according to the present invention are not limited to the descriptions of the following embodiments.

[0052] Embodiment 1:

[0053] A system for measuring the characteristics of a mixed gas phase, as Figures 1-3 shown, includes:

[0054] A temperature control system, which is arranged in the vacuum container and is used to control the temperature in the equilibrium kettle to be constant and display the temperature of the constant temperature bath wall surface;

[0055] A gas storage system, which is used to store the gases to be tested and realize the supply of three gases to be tested;

[0056] A buffer system, which is arranged between the equilibrium kettle and the gas storage system and is used to ensure the stability of the pressure in the equilibrium kettle;

[0057] A gas phase equilibrium system, which is connected to the equilibrium kettle through an intake circulation pipeline and is used to carry the mixture to be tested and keep it in equilibrium.

[0058] Furthermore, it further includes a magnetic stirring system, which is used to stir the gas in the equilibrium kettle to accelerate the phase equilibrium.

[0059] Furthermore, it also includes a data acquisition system, which measures the temperature, pressure and gas-phase composition of the mixed system through a temperature sensor, a pressure sensor and a gas chromatograph.

[0060] Example 2:

[0061] A system for measuring the characteristics of a mixed gas phase, with other structures similar to those in Example 1. Furthermore, the temperature sensor is a pt25 platinum resistance thermometer.

[0062] Furthermore, the pressure sensor is a Mensor CPT6010 absolute pressure sensor or a GE UNIK5000 differential pressure sensor.

[0063] Furthermore, the water vapor storage system includes a water tank and a heater.

[0064] Furthermore, the heater is a constant temperature system with a temperature upper limit of 160 °C or higher.

[0065] Furthermore, a constant temperature bath system is provided inside the equilibrium kettle, and there are two symmetric visible windows on it.

[0066] Furthermore, the volume of the constant temperature bath system is 6.5L, made of stainless steel, and its outside is covered with aluminized polyester film.

[0067] Example 3:

[0068] A system for measuring the characteristics of a mixed gas phase, as Figure 1 shown, includes:

[0069] A water vapor generator 18, which is composed of a water tank and a heater. The heater is a constant temperature device with a relatively high temperature upper limit (160 °C or higher), and this system is used to generate water vapor for testing;

[0070] An equilibrium kettle 13, the constant temperature bath device of this device has a volume of 6.5L, is processed by stainless steel, is covered with aluminized polyester film on the outside, and has two symmetric visible windows. It is a container for the mixed gas to be fully mixed to reach equilibrium, and the gas mixing state inside the equilibrium kettle 13 can be identified from the outside;

[0071] A second motor 7, which drives a magnetic stirrer to stir;

[0072] A magnetic stirrer 14, placed in the equilibrium kettle 13, used for stirring to enable the mixed gas to quickly reach equilibrium;

[0073] A constant temperature liquid bath 11, used to keep the temperature of the mixed gas in the equilibrium kettle 13 constant;

[0074] A refrigeration unit 2, used to cool the constant temperature liquid bath to prevent the temperature from being too high;

[0075] An electric heater 12 for heating the constant temperature liquid bath to prevent the temperature from being too low;

[0076] A first motor 6 drives a stirrer in the constant temperature liquid bath to fully mix the liquid in the constant temperature liquid bath and ensure the consistency of the overall temperature;

[0077] A pressure transmitter 15 is placed between the equilibrium kettle and the buffer tank to ensure that the pressure in the equilibrium kettle remains constant;

[0078] A first buffer tank 16 and a second buffer tank 17 are placed between the equilibrium axe and the gas storage device to buffer the flow of gas caused by the pressure difference;

[0079] A temperature and pressure indicator 4 directly displays the corresponding temperature and pressure values through a sensor;

[0080] A gas chromatograph 5 is used to determine the composition of the gas phase components.

[0081] Example 4:

[0082] A system for measuring the characteristics of a mixed gas phase state, as Figure 1 shown. Other structures are similar to those in Example 3. Further, it further includes:

[0083] An electric heating controller 3 for controlling the electric heater 12;

[0084] A vacuum pump 8 for evacuating / pressurizing;

[0085] A vacuum container 9 is connected to the vacuum pump 8 and is used to provide a vacuum environment for the experiment;

[0086] A cooling coil 10 is connected to the refrigeration unit 2 and is used to cool the constant temperature liquid bath to prevent the temperature from being too high;

[0087] A steam generator 18 is connected to the second buffer tank 17 to generate steam.

[0088] Example 5:

[0089] A system for measuring the characteristics of a mixed gas phase state, as Figure 1 shown. Other structures are similar to those in Example 4. Further, it further includes:

[0090] (1) The sampling pipeline uses a very short and thin copper pipe and is directly connected to the downward pipeline of the circulation pump, so that the working medium enters the bottom of the equilibrium kettle 13 along the circulation pipeline and is mixed with the previously charged liquid working medium at the same time;

[0091] (2) Three round holes are provided in the upper part of the equilibrium kettle 13, and a capillary seat, a thermometer sleeve, and a copper pipe are welded in sequence;

[0092] (3) The capillary seat has 5 small holes. The middle hole has a diameter of 1 mm, and a capillary with an outer diameter of 0.8 mm is soldered to connect the pressure sensor. The four holes on both sides have a diameter of 0.7 mm, and four capillaries with an outer diameter of 0.5 mm and an inner diameter of 0.35 mm are soldered as sampling pipelines.

[0093] (4) The four capillary sampling pipelines are at different heights. The highest one is the gas-phase sampling pipeline, and the other three are liquid-phase sampling pipelines, which can collect liquid-phase components at different liquid levels.

[0094] (5) The thermometer sleeve is made of copper rod, with the closed end at the bottom, about 15 mm from the bottom of the equilibrium kettle. A Pt25 platinum resistance thermometer is placed inside, filled with thermal conductive silicone grease to ensure good heat conduction between the platinum resistance and the sleeve.

[0095] Example 6:

[0096] A method for measuring the characteristics of a mixed gas phase includes the following steps:

[0097] S1 System assembly and leak detection: Connect the components of the system, conduct vacuum leak detection on the system, and then conduct pressure leak detection. If there is a leak, check for the leak point.

[0098] S2 Filling of the working fluid to be measured: Fill the mixed gas into the equilibrium kettle.

[0099] S3 Temperature control: Adjust the power of the electric heater to maintain a constant temperature until the system reaches stability.

[0100] S4 Data acquisition: Obtain the peak area and height of various substances in the mixed gas on the chromatographic column, calibrate the gas chromatograph with the prepared standard gas, and obtain the gas-phase mole fraction of the mixed gas.

[0101] Further, in step S1, the vacuum leak detection includes: evacuating the system, then leaving it for a period of time, and observing the change in the reading of the pressure sensor. If the reading of the pressure sensor does not change for a long time, it indicates that the system is well sealed in the vacuum state. If the reading of the pressure sensor continues to rise and finally reaches 0.1 MPa, it indicates that the system leaks, and check for the leak point.

[0102] Further, in step S1, the pressure leak detection includes: applying a positive pressure of 1.5 MPa, observing the pressure sensor, and after leaving the system for a long time, observing whether the reading decreases. If the reading is gradually decreasing, it proves that there is a leak in the experimental system, and check for the leak point.

[0103] Further, in step S1, the check for the leak point includes:

[0104] (1) First, check whether the equilibrium kettle leaks; close the second valve ( Figure 3Middle valve 2), open the first valve ( Figure 3 Middle valve 1), third valve ( Figure 3 Middle valve 3) for vacuum pumping or pressurization operation. After vacuum pumping or pressurization, leave it for a relatively long time and observe the changes in the readings of the two pressure sensors. If the readings do not change, it indicates that there is no leakage inside the equilibrium kettle, and the leak point is in the buffer tank; if the readings change significantly, the equilibrium kettle leaks and needs to be disassembled for repair;

[0105] (2) After ensuring that the equilibrium kettle does not leak, check whether the buffer tank leaks; open the first valve, second valve, and third valve, pressurize the system to 1.5 MPa, apply soap bubbles to the 3 solder joints, and see if there are bubbles slowly emerging. If leakage is found, fill the leak point with solder, and then repeatedly pressurize and check for leaks. If the leakage of the three solder joints cannot be observed with soap bubbles and the readings of the pressure sensor always decrease, consider replacing the PTFE gasket connecting the pressure sensor.

[0106] Further, in step S2, first evacuate the system, and then connect the system: the working medium tank is directly connected to the equilibrium kettle, the high-pressure nitrogen cylinder is directly connected to the buffer tank, and pressure sensors are connected to both the equilibrium kettle and the buffer tank.

[0107] Further, in step S2, the filling of the working medium to be measured includes:

[0108] S21 After connecting the system, close the first valve and the second valve, slowly open the working medium tank for purging to exhaust the residual air in the rubber hose; after purging is completed, connect it to the first valve, and at this time, there is a certain amount of residual working medium in the rubber hose;

[0109] S22 Slowly open the first valve to allow the working medium in the rubber hose to slowly enter the equilibrium kettle, and at the same time observe the readings of the pressure sensor and the differential pressure sensor; since the inside of the current equilibrium kettle is in a vacuum state, the intake speed is extremely fast, so special attention should be paid to the change in the reading of the differential pressure sensor during this process. When the voltage signal output by the differential pressure sensor reaches 4 - 5 V, immediately close the first valve;

[0110] S23 Slowly open the second valve to add N2 to the buffer tank and observe the reading of the differential pressure sensor. When the voltage signal of the differential pressure sensor drops to about 1.03 V, close the second valve;

[0111] S24 Slowly open the first valve, pay special attention to the reading of the differential pressure sensor, and fill all the residual gas in the rubber hose into the equilibrium kettle. If the reading of the differential pressure sensor is less than 4 V at this time, slowly open the valve of the working medium tank for filling the working medium. After the reading reaches 4 V, close the first valve and the valve of the working medium tank;

[0112] S25 Repeat steps S23 and S24 until the reading of the pressure sensor reaches the pressure value required for the experiment.

[0113] Further, in step S3, the power of the electric heater is adjusted by PID programming to maintain a constant temperature.

[0114] Further, in step S3, the PID control process is as follows: First, the error is obtained based on the feedback temperature and the desired temperature, then the proportional, integral, and differential calculations are performed according to this error value, and finally the calculated proportional, integral, and differential terms are summed to obtain the control temperature.

[0115] Further, in step S1, the conditions for the system to reach stability are: the temperature reaches the set value for more than 40 minutes, and the temperature fluctuation is less than 3 mK, and the pressure fluctuation is less than 200 Pa.

[0116] Further, in step S4, first, the peak areas and heights of various substances on the chromatographic column are obtained using a gas chromatograph. Then, a standard gas is prepared by the weighing method using a high-precision electronic analytical balance, and the gas chromatograph is calibrated using the prepared standard gas to obtain the accurate gas-phase mole fraction.

[0117] Example 6:

[0118] A method for measuring the characteristics of a mixed gas phase state, comprising the following steps:

[0119] Step 1: First, evacuate the system, open the valve of the working fluid tank for working fluid filling, and fill the equilibrium kettle with steam, CO2, and N2 gases in a ratio of 50% H2O / 30% CO2 / 20% N2.

[0120] Step 2: Turn on the magnetic stirrer and stir for 1.5 h, then let it stand for 3 hours to make the system reach phase equilibrium. Open the LABVIEW program, and adjust the power of the electric heater to adjust the temperature to 400 K through PID programming of LABVIEW.

[0121] Step 3: When the system temperature reaches the set value for more than 40 minutes, and the temperature fluctuation is less than 3 mK, and the pressure fluctuation is less than 200 Pa, the system is considered to reach stability. Sample the pressure, and the pressure is 0.37196 MPa.

[0122] Step 4: Open the gas chromatograph and sample the gas-phase mole fraction to obtain the experimental data of the ternary mixed-phase system Example 7: The experimental data of the present invention for measuring the characteristics of the steam, CO2, and N2 mixed gas phase state

[0123] The p-T data of 50% H2O / 30% CO2 / 20% N measured using the device of the present invention 2 is as Figure 4 shown. Compared with the calculation data of REFPROP 10.0, the absolute average uncertainty is 0.9332%.

[0124] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as falling within the protection scope of the present invention.

Claims

1. A system for measuring the characteristics of a mixed gas phase, characterized in that, it includes: A temperature control system, which is arranged inside a vacuum container and is used to control the temperature inside the equilibrium kettle to keep it constant and display the temperature of the constant temperature bath wall surface; A gas storage system, which is used to store the gases to be tested and realize the supply of three gases to be tested; A buffer system, which is arranged between the equilibrium kettle and the gas storage system and is used to ensure the stability of the pressure inside the equilibrium kettle; A gas phase equilibrium system, which is connected to the equilibrium kettle through an intake air circulation pipeline and is used to carry the mixture to be tested and keep it in equilibrium.

2. A system for measuring the characteristics of a mixed gas phase according to claim 1, characterized in that: It further includes a magnetic stirring system, which is used to stir the gas inside the equilibrium kettle to accelerate the phase equilibrium.

3. A system for measuring the characteristics of a mixed gas phase according to claim 1, characterized in that: It further includes a data acquisition system, which measures the temperature, pressure and gas phase composition of the mixed system through a temperature sensor, a pressure sensor and a gas chromatograph.

4. A system for measuring the characteristics of a mixed gas phase according to claim 3, characterized in that: The temperature sensor is a pt25 platinum resistance thermometer.

5. A system for measuring the characteristics of a mixed gas phase according to claim 3, characterized in that: The pressure sensor is a Mensor CPT6010 absolute pressure sensor or a GE UNIK5000 differential pressure sensor.

6. A system for measuring the characteristics of a mixed gas phase according to claim 3, characterized in that: The water vapor storage system includes a water tank and a heater.

7. A system for measuring the characteristics of a mixed gas phase according to claim 6, characterized in that: The heater is a constant temperature system with a temperature upper limit of 160 °C or above.

8. A system for measuring the characteristics of a mixed gas phase according to claim 6, characterized in that: A constant temperature bath system is arranged inside the equilibrium kettle, and there are two symmetric visual windows on it.

9. A system for measuring the characteristics of a mixed gas phase according to claim 8, characterized in that: The constant temperature bath system has a volume of 6.5L, is made of stainless steel, and is coated with aluminized polyester film on the outside.

10. A method for measuring the characteristics of a mixed gas phase, characterized in that, it includes the following steps: S1 System assembly and leak detection: Connect the components of the system, perform vacuum leak detection on the system, and then perform pressure leak detection. If there is a leakage situation, check for the leakage point; S2 Filling of the working medium to be tested: Fill the mixed gas into the equilibrium kettle; S3 Temperature control: Adjust the power of the electric heater to maintain a constant temperature until the system reaches stability; S4 Data acquisition: Obtain the peak area and height of various substances in the mixed gas on the chromatographic column, calibrate the gas chromatograph with the prepared standard gas, and obtain the gas phase mole fraction of the mixed gas.

11. A method for measuring the characteristics of a mixed gas phase according to claim 10, characterized in that, In the step S1, the decompression leak detection includes: evacuating the system to vacuum, then leaving it for a period of time, and observing the change in the reading of the pressure sensor. If the reading of the pressure sensor does not change for a long time, it indicates that the system has good airtightness in the vacuum state. If the reading of the pressure sensor continues to rise and finally reaches 0.1 MPa, it indicates that the system leaks, and the leak point needs to be checked.

12. A method for measuring the characteristics of a mixed gas phase as described in claim 10, characterized in that: In the step S1, the pressurization leak detection includes: applying a positive pressure of 1.5 MPa, observing the pressure sensor, and after leaving the system for a long time, observing whether the reading decreases. If the reading is gradually decreasing, it proves that there is a leak in the experimental system, and the leak point needs to be checked.

13. A method for measuring the characteristics of a mixed gas phase as described in claim 10, characterized in that: In the step S1, the leak point check includes: (1) First, check whether the equilibrium kettle leaks; close the second valve, open the first valve and the third valve for evacuation or pressurization operations. After evacuation or pressurization, leave it for a long time and observe the change in the readings of the two pressure sensors. If the readings do not change, it indicates that there is no leakage inside the equilibrium kettle, and the leak point is in the buffer tank. If the readings change significantly, the equilibrium kettle leaks and needs to be disassembled for repair; (2) After ensuring that the equilibrium kettle does not leak, then check whether the buffer tank leaks; open the first valve, the second valve, and the third valve, pressurize the system to 1.5 MPa, apply soap bubbles to the 3 solder joints, and see if there are bubbles slowly emerging. If a leak is found, fill the leak point with solder, and then repeatedly pressurize for leak detection. If the leakage of the three solder joints cannot be observed with soap bubbles and the reading of the pressure sensor always decreases, consider replacing the Teflon gasket connecting the pressure sensor.

14. A method for measuring the characteristics of a mixed gas phase as described in claim 10, characterized in that: In the step S2, first evacuate the system, and then connect the system: directly connect the working medium tank to the equilibrium kettle, directly connect the high-pressure nitrogen cylinder to the buffer tank, and both the equilibrium kettle and the buffer tank are connected to the pressure sensor.

15. A method for measuring the characteristics of a mixed gas phase as described in claim 10, characterized in that: In the step S2, the filling of the working medium to be measured includes: S21 After connecting the system, close the first valve and the second valve, slowly open the working medium tank for purging to exhaust the residual air in the rubber tube; after purging is completed, connect it to the first valve. At this time, there is a certain amount of residual working medium in the rubber tube; S22 Slowly open the first valve to allow the working medium in the rubber tube to slowly enter the equilibrium kettle, and at the same time observe the readings of the pressure sensor and the differential pressure sensor; since the equilibrium kettle is currently in a vacuum state, the intake speed is extremely fast, so special attention should be paid to the change in the reading of the differential pressure sensor during this process. When the voltage signal output by the differential pressure sensor reaches 4 - 5 V, immediately close the first valve; S23 Slowly open the second valve to add N2 into the buffer tank, and observe the reading of the differential pressure sensor. When the voltage signal of the differential pressure sensor drops to about 1.03V, close the second valve; S24 Slowly open the first valve, pay special attention to the reading of the differential pressure sensor, and fill all the residual gas in the rubber tube into the equilibrium still. If the reading of the differential pressure sensor is less than 4V at this time, slowly open the valve of the working medium tank to fill the working medium. After the reading reaches 4V, close the first valve and the valve of the working medium tank; S25 Repeat steps S23 and S24 until the reading of the pressure sensor reaches the pressure value required for the experiment.

16. A method for measuring the characteristics of a mixed gas phase as claimed in claim 10, characterized in that: In step S3, the power of the electric heater is adjusted by PID programming to maintain a constant temperature.

17. A method for measuring the characteristics of a mixed gas phase as claimed in claim 16, characterized in that: In step S3, the PID control process is as follows: First, calculate the error based on the feedback temperature and the desired temperature, then perform calculations for the proportional, integral, and derivative terms based on this error value, and finally sum up the calculated proportional, integral, and derivative terms to obtain the control temperature.

18. A method for measuring the characteristics of a mixed gas phase as claimed in claim 10, characterized in that: In step S1, the conditions for the system to reach stability are: the temperature reaches the set value for more than 40 minutes, and the temperature fluctuation is less than 3mK, and the pressure fluctuation is less than 200Pa.

19. A method for measuring the characteristics of a mixed gas phase as claimed in claim 10, characterized in that: In step S4, first, use a gas chromatograph to obtain the peak area and height of various substances on the chromatographic column. Then, use a high-precision electronic analytical balance to prepare a standard gas by the weighing method, and use the prepared standard gas to calibrate the gas chromatograph to obtain the accurate gas phase mole fraction.

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