In-situ testing device for gas-liquid equilibrium phase diagram of two-component system

Abstract

The invention relates to a two-component system gas-liquid equilibrium phase diagram in-situ testing device which comprises a gas-liquid equilibrium kettle, a gas-phase quantitative sampling assembly, a liquid-phase sampler, a thermostat and a gas chromatograph, the gas-liquid equilibrium kettle and the gas-phase quantitative sampling assembly are both arranged in the thermostat, the liquid-phase sampler can be inserted into the gas-liquid equilibrium kettle through a liquid-phase sampling opening so as to suck a liquid-phase sample, and the gas-phase quantitative sampling assembly is arranged in the thermostat. The gas chromatograph is connected with the gas phase quantitative sampling assembly through the carrier gas system, and the gas phase quantitative sampling assembly comprises a quantitative loop pipe, a first four-way valve, a second four-way valve and a balloon. The device has the advantages that in-situ sampling is carried out on the gas phase, the phase number in the system is not changed, and the limitation that the theoretical accuracy is influenced by gas phase condensation of an original device is broken through; the volume of the quantitative loop pipe is relatively small, gas-liquid balance in the system cannot be influenced by sampling, and the experiment accuracy is high; the method meets the requirement of phase law, enables the experiment to accord with the physical and chemical basic theory, provides an important reference for the reasonability and correctness of the experiment, and is of great significance for experiment teaching and academic research.

Description

Technical Field

[0001] This invention relates to a physicochemical experimental apparatus, specifically to an in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system. Background Technology

[0002] The phase diagram experiment for the gas-liquid equilibrium of a two-component system is a fundamental experiment on phase equilibrium in physical chemistry and a classic experiment required in university physical chemistry courses. Its most compelling aspect lies in its design based on the most elegant law in physical chemistry—the phase rule—and its aim to help students grasp the basic principles and experimental procedures of the phase rule. In undergraduate teaching experiments, this experiment not only involves a large amount of data and a long operation time, but also requires certain operational skills in many steps. The operation of the instruments and data processing are also quite complex, often making it difficult for beginners to achieve satisfactory results in a short time. Although improvements and discussions on this experiment have been ongoing, most have focused on reducing operational steps and improving experimental accuracy, with few reports addressing the theoretical problems inherent in the experiment.

[0003] The current undergraduate physical chemistry experiment textbooks mainly use the "Physical Chemistry Experiments" textbook compiled by Fudan University. The experimental setup for the gas-liquid equilibrium phase diagram experiment of a two-component system in this textbook, such as... Figure 1 As shown, the apparatus includes a long-necked, round-bottom flask with a condenser side arm. A small, round glass bulb at the bottom of the condenser arm collects the condensed gas sample. This experimental setup has several drawbacks: uneven heating, long equilibration time, inconvenient sampling, non-in-situ detection, high reagent consumption, and increased experimental error due to sample changes during sampling. Among these, the sampling of gaseous substances is a focal point affecting the overall accuracy of the experiment and has generated considerable discussion among researchers. To facilitate gaseous sampling, some researchers have designed various improved boiling point apparatuses, addressing the sampling difficulty from different angles. However, the experimental design also contains unrecognized theoretical flaws that violate fundamental thermodynamic principles.

[0004] Various physical chemistry experiment manuals interpret the number of phases P in the system of this experimental setup as 2, one being the gas phase and the other the liquid phase, with the number of components C set to 2, such as ethanol and n-propanol. According to the phase rule, F = C - P + n = 2 - 2 + n. When the pressure is constant, n = 1, so the degree of freedom F = 2 - 2 + 1 = 1. If the temperature is further determined, the number of components is also determined, and vice versa. Currently, one of the theoretical problems of this experimental setup is that the detection of the gas phase in the experimental system requires collecting the condensate through a condenser and measuring the composition of the condensate using a refractometer, using this condensate composition to represent the gas phase composition of the system. However, the condensed liquid (representing the gas phase composition) is not consistent with the composition of the two-component liquid in the round-bottom flask (representing the liquid phase composition). According to the principles of physical chemistry, the composition within the same phase should be homogeneous. Therefore, the two liquids with inconsistent compositions should be considered as two different phases, meaning that the gas phase condensate should theoretically form its own phase; otherwise, it would contradict the principles of physical chemistry. Therefore, the actual number of phases P in the system is not 2, but 3, which conflicts with the experimental principle in the textbook that the number of phases is 2. In reality, the three phases in the system are two liquid phases and one gas phase. For a three-phase system, P is 3, C is still 2 (the two components are still ethanol and n-propanol), and the pressure is a fixed value. Then F = C - P + 1 = 2 - 3 + 1 = 0. Before the temperature is even set, the degree of freedom is already 0, so this theoretical result violates the original experimental principle. In the actual operation of this experiment, the number of components and temperature are related, and the apparent degree of freedom of students conducting the experiment is 1, which contradicts the theory. The second theoretical problem with this experimental setup is that the two liquid components in the round-bottom flask vaporize when heated, and the vaporized gas is condensed through the condenser. Under the combined effect of these two processes, the temperature in the system no longer changes, thus creating the illusion of thermodynamic equilibrium. This macroscopically separated phenomenon of boiling and condensation does not satisfy the basic conditions for phase equilibrium.

[0005] This experiment suffers from the two problems mentioned above. Based on these problems, it can be concluded that under the existing experimental conditions, a true equilibrium is not formed between the phases; instead, different phase transition processes occur simultaneously at both the heating and condensation sites. The long-standing existence of these two main problems has inevitably led to a cross-century misunderstanding among students regarding the fundamental principles of the phase rule and phase equilibrium. Furthermore, the lack of in-depth analysis of these problems in teaching significantly reduces the teaching effectiveness of this experiment and fails to achieve the original purpose of the experimental teaching design. Summary of the Invention

[0006] This invention provides an in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system. Its purpose is to eliminate long-standing contradictions between physical chemistry theory and experimental design, solve core problems in physical chemistry experimental teaching, improve experimental quality, overcome the design limitations of the experiment under existing experimental device systems, eliminate the interference of gas-phase condensate on the system, and make the experimental device conform to the experimental principle.

[0007] The technical solution of this invention to solve the above-mentioned technical problems is as follows: An in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system, comprising a gas-liquid equilibrium vessel, a gas phase quantitative sampling component, a liquid phase sampler, a thermostat, and a gas chromatograph. The gas-liquid equilibrium vessel and the gas phase quantitative sampling component are both placed inside the thermostat. The gas-liquid equilibrium vessel has a gas phase sampling port and a liquid phase sampling port. The gas phase sampling port is connected to the gas phase quantitative sampling component. The liquid phase sampling port allows the liquid phase sampler to be inserted into the gas-liquid equilibrium vessel to aspirate a liquid phase sample. The gas chromatograph is connected to the gas phase equilibrium vessel via a carrier gas system. The gas phase quantitative sampling assembly is connected, and the gas phase quantitative sampling assembly includes a quantitative loop tube, a first four-way valve, a second four-way valve, and a balloon. The first four-way valve's interface one and interface four are respectively connected to two ports of one access point of the quantitative loop tube. The first interface and the second interface of the second four-way valve are respectively connected to two ports of the other access point of the quantitative loop tube. The first four-way valve is connected to the carrier gas system through interface two and interface three. The third interface and the fourth interface of the second four-way valve are respectively connected to the balloon and the gas phase sampling port.

[0008] Based on the above technical solution, the present invention can be further improved as follows.

[0009] Furthermore, the thermostat is a constant temperature water bath device, which includes a water bath tank, a stirrer, a heater, and a thermocouple.

[0010] Furthermore, the thermostat is a constant temperature hot air circulating oven.

[0011] Furthermore, the gas-liquid equilibrium vessel is a flask, the liquid phase sampling port is the top opening of a liquid phase sampling tube vertically located at the top of the flask and communicating with the inside of the flask, the liquid phase sampling port is sealed with a rubber cap, and the liquid phase sampler has a sampling needle that can pierce the rubber cap and enter the flask to take a sample.

[0012] Furthermore, the gas sampling port is the opening at the end of the gas sampling tube away from the flask, the gas sampling port is connected to the top of the flask, and a barometer is connected to the gas sampling tube.

[0013] Furthermore, the carrier gas system includes a carrier gas cylinder and a carrier gas tube. The two ends of the carrier gas tube are respectively connected to the gas outlet of the carrier gas cylinder and the sample inlet of the gas chromatograph. The middle part of the carrier gas tube is connected to interface two and interface three of the first four-way valve.

[0014] Furthermore, the capacity of the quantitative loop is 2-5 mL.

[0015] Furthermore, the first four-way valve and the second four-way valve are manual valves or power valves.

[0016] Furthermore, when the first four-way valve and the second four-way valve are manual valves and the thermostat is a constant temperature water bath device, the manual valve is immersed in the water bath of the constant temperature water bath device, and the adjusting handle of the manual valve is located above the water bath surface.

[0017] Furthermore, the quantitative loop tube is a glass tube, a plastic tube, a stainless steel tube, or a composite material tube.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This invention enables in-situ sampling and monitoring of gaseous substances in a gas-liquid equilibrium binary system using a gas-phase quantitative sampling component. The sampling process does not alter the number of phases within the system, overcoming the limitation of existing devices that suffer from forced condensation of gaseous substances, leading to condensation phase aggregation and affecting theoretical accuracy. Furthermore, because the volume of the quantitative loop is relatively small compared to the system volume, the extracted gaseous sample has almost no impact on the gas-liquid equilibrium, improving experimental accuracy. More importantly, this scheme meets the requirements of the phase rule, ensuring the experiment conforms to fundamental physical chemistry theories and providing important guidance for the rationality and correctness of the experiment. This invention is of significant importance for experimental teaching and academic research. The testing device provided by this invention is ingeniously designed, simple in structure, and can be mass-produced, replacing almost all domestic and international experimental devices for gas-liquid equilibrium phase diagrams of binary systems. Attached Figure Description

[0020] Figure 1 This is the experimental setup used in the gas-liquid equilibrium phase diagram experiment for binary systems in current physical chemistry experimental textbooks;

[0021] Figure 2 A schematic diagram of the in-situ testing device for the gas-liquid equilibrium phase diagram of a two-component system provided by the present invention;

[0022] Figure 3 for Figure 2 The schematic diagram of the gas phase quantitative sampling component in the in-situ testing device shown is in the conventional sampling state where the quantitative loop tube is connected to the gas of the two-component system, and the balloon is not shown.

[0023] Figure 4 for Figure 2 The schematic diagram of the gas phase quantitative sampling component in the in-situ testing device shown is in a pre-sampling state where the quantitative loop sampling is completed and relatively isolated (the balloon is not shown).

[0024] Figure 5 for Figure 2 The schematic diagram of the gas phase quantitative sampling component in the in-situ testing device shown is in the sample injection state with the quantitative loop tube connected to the carrier gas system (the balloon is not shown).

[0025] The attached diagram lists the components represented by each number as follows:

[0026] 1. Gas-liquid equilibrium vessel; 2. Gas chromatograph; 3. Quantitative loop tube; 4. First four-way valve; 5. Second four-way valve; 6. Balloon; 7. Water bath; 8. Stirrer; 9. Heater; 10. Thermocouple; 11. Rubber cap; 12. Barometer; 13. Carrier gas cylinder; 141. Interface 1; 142. Interface 2; 143. Interface 3; 144. Interface 4; 241. First interface; 242. Second interface; 243. Third interface; 244. Fourth interface. Detailed Implementation

[0027] The principles and features of the present invention are described below with reference to the accompanying drawings and specific embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0028] In the description of this invention, if terms such as "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer" are used to indicate the orientation or positional relationship, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] The current undergraduate physical chemistry experiment textbook mainly uses the "Physical Chemistry Experiment" textbook compiled by Fudan University. The experimental setup (boiling point apparatus) for the gas-liquid equilibrium phase diagram experiment of the two-component system in this textbook is as follows: Figure 1 As shown, it has theoretical defects in that it is not essentially a two-phase system and has not actually formed a thermodynamic equilibrium, as stated in the background section, and will not be repeated here.

[0030] In one embodiment of the present invention, such as Figures 2 to 5As shown, an in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system is provided. It includes a gas-liquid equilibrium vessel 1, a gas phase quantitative sampling component, a liquid phase sampler, a thermostat, and a gas chromatograph 2. The gas-liquid equilibrium vessel 1 and the gas phase quantitative sampling component are both placed inside the thermostat. The gas-liquid equilibrium vessel 1 has a gas phase sampling port and a liquid phase sampling port. The gas phase sampling port is connected to the gas phase quantitative sampling component. The liquid phase sampling port allows the liquid phase sampler to be inserted into the gas-liquid equilibrium vessel 1 to aspirate a liquid phase sample. The gas chromatograph 2 is connected to the gas phase quantitative sampling component via a carrier gas system, and the carrier gas system delivers the sample from the gas phase quantitative sampling component into the gas-liquid equilibrium vessel 2. The gas chromatograph performs the detection. The gas chromatograph quantitative sampling assembly includes a quantitative loop tube 3, a first four-way valve 4, a second four-way valve 5, and a balloon 6. The first four-way valve 4 has its interface 141 and interface 144 connected to two ports at one access point of the quantitative loop tube 3, respectively. The second four-way valve 5 has its first interface 241 and second interface 242 connected to two ports at the other access point of the quantitative loop tube 3, respectively. The first four-way valve 4 is connected to the carrier gas system through interface 2 142 and interface 3 143. The second four-way valve 5 has its third interface 243 and fourth interface 244 connected to the balloon 6 and the gas sampling port, respectively.

[0031] It should be noted that isolating the system from the outside world creates a relatively closed and independent system. This avoids material loss affecting the accuracy of the test results during the two-component system throughout the testing process. Furthermore, the inflatable balloon ensures that the total pressure within the two-component system remains essentially constant throughout the experiment, thus guaranteeing relatively accurate test results. The initial pressure of both the balloon and the two-component system is approximately atmospheric pressure and can be measured using a pressure gauge. Although the balloon exhibits some surface tension during inflation, this tension is relatively small compared to atmospheric pressure for a typical balloon. The balloon tension pressure essentially corresponds to the change in system pressure during the test. The ratio of this change to atmospheric pressure is the pressure change rate. Since the rate of change is very small, the entire test process can be considered to be conducted under essentially constant pressure conditions. At least compared to a non-inflating system, the two-component system with the balloon in this invention is closer to constant pressure throughout the entire testing process. The radius of the balloon can be chosen to be slightly larger. When the balloon's radius is around 40cm and it is inflated, the internal pressure change is at most a few hundred Pascals during the test, even if the balloon only expands a few centimeters. This is only a few thousandths of an atmospheric pressure (0.1 MPa), which can be considered essentially constant pressure. Furthermore, there is a minimum value for the balloon's internal pressure as a function of its radius. Generally, a 40cm balloon corresponds to the minimum additional pressure. If the balloon is inflated to 38cm before the experiment and then expanded to 42cm after the experiment, the change in internal pressure is almost zero. This means that by precisely controlling the balloon size according to the experimental requirements, the pressure change within the system can be further reduced.

[0032] In one embodiment of the present invention, the thermostat can be a constant temperature water bath device, such as... Figure 2 As shown, the constant temperature water bath device includes a water bath 7, a stirrer 8, a heater 9, and a thermocouple 10 for quantitative sampling. The stirrer ensures uniform water bath temperature, the heater accelerates the water bath process, and the thermocouple monitors the water temperature. The gas phase quantitative sampling assembly, including the balloon, is placed as evenly as possible in the water bath to ensure that the gas and liquid phases have the same and constant temperature, while avoiding condensation of the gas phase due to temperature differences, and preventing the formation of a second liquid phase independent of the liquid phase at the bottom of the flask. A temperature sensor or thermometer for measuring the liquid phase temperature should also be installed in the gas-liquid equilibrium vessel to obtain the temperature of the liquid phase of the two-component system in a timely and accurate manner. The liquid phase sampler can take various forms, including but not limited to pipettes or syringes with sampling needles.

[0033] It is understandable that the above-mentioned constant temperature water bath device can also be replaced by a constant temperature hot air circulating oven, which can also ensure the adjustment of experimental temperature and the uniformity of gas and liquid phase temperatures.

[0034] In one embodiment of the present invention, the gas-liquid equilibrium vessel 1 is a flask, and the liquid phase sampling port is the top opening of a liquid phase sampling tube vertically disposed at the top of the flask and communicating with the interior of the flask. A rubber cap 11 is sealed at the liquid phase sampling port. The liquid phase sampler has a sampling needle that can pierce the rubber cap 11 and enter the flask to take a sample. The gas phase sampling port is the opening at the end of the gas phase sampling tube furthest from the flask, and the gas phase sampling port communicates with the top of the flask. To intuitively understand the gas pressure within the two-component system, in this embodiment, a barometer 12 is connected to the gas phase sampling tube.

[0035] In the above embodiments, the carrier gas system includes a carrier gas cylinder 13 and a carrier gas tube. The two ends of the carrier gas tube are connected to the gas outlet of the carrier gas cylinder 13 and the sample inlet of the gas chromatograph, respectively. The middle part of the carrier gas tube is connected to interface 142 and interface 143 of the first four-way valve 4. The capacity of the quantitative loop tube 3 is 2-5 mL, preferably 5 mL. The first four-way valve 4 and the second four-way valve 5 are manual valves or power valves. When they are power valves, they can be electric or pneumatic valves. When the first four-way valve 4 and the second four-way valve 5 are manual valves and the thermostat is a constant temperature water bath device, the manual valve is immersed in the water bath of the constant temperature water bath device, and the adjusting handle of the manual valve is above the water bath surface, thus facilitating manual adjustment of the manual valve. The quantitative loop tube 3 is a glass tube, plastic tube, stainless steel tube, or composite material tube. The composite material tube can specifically be a metal-plastic composite tube.

[0036] The coordination of the first four-way valve and the second four-way valve in the gas phase quantitative sampling component of the in-situ testing device for the gas-liquid equilibrium phase diagram of the two-component system corresponding to the above embodiments during testing is as follows: Figures 3 to 5 As shown: During the test, the pressure was normal, the thermostat temperature was set to a preset value, the balloon contained only a small amount of air and was open to the atmosphere, and the balloon interface was connected to the third interface 243. Figure 3 In this configuration, the metering loop is connected to the gas phase of the two-component system. Both the first and second four-way valves are in their first state. At this time, ports 141 and 144 are open, ports 142 and 143 are open and connected to the carrier gas system, ports 241 and 244 are open, connecting the metering loop to the gas phase of the two-component system, and ports 242 and 243 are open. After a period of time, the gas phase in the metering loop becomes the gas phase of the two-component system. Figure 4 In this configuration, the quantitative loop is disconnected from the two-component system. The first four-way valve remains in its first state, while the second four-way valve is switched to its second state via a rotary interface switching valve. Specifically, the first interface 241 is connected to the second interface 242, and the third interface 243 is connected to the fourth interface 244. At this time, the quantitative loop is relatively isolated and closed, containing the quantitatively sampled gaseous sample of the two-component system. This is the pre-injection state, ready for injection into the gas chromatograph. Figure 5 In the initial stage, the quantitative loop is connected to the carrier gas system (injection state). At this time, both the first and second four-way valves are in their second state, with interface 141 and interface 142 connected, and interfaces 143 and 144 connected. The carrier gas carries the gaseous sample from the quantitative loop into the gas chromatograph for detection. After injection, rotate the interface switching valves of both four-way valves to return them to their first state (normal state). The quantitative loop is then reconnected to the two-component system, and the chromatographic result is the gas phase composition. After a few minutes, switch the four-way valve assembly from the normal state to the pre-injection state and then back to the injection state, and re-detect the gas phase composition. Repeat this process three times. If the gas phase composition does not change during these three detections, the system can be considered to have reached equilibrium. Simultaneously with each gas phase sample analysis, a liquid sample can be taken for analysis using headspace sampling (using a liquid chromatograph with a sampling needle) (refractive index determination or gas chromatography to determine its composition). The headspace sampling port is equipped with a rubber cap or stopper to prevent gas leakage (the rubber cap or stopper can also be replaced by an openable and closable sealing cover). When measuring phase equilibrium data at other temperatures, the temperature of the isothermal bath needs to be reset, and the above method can be used for measurement.

[0037] The following uses the in-situ testing device for the vapor-liquid equilibrium phase diagram of a two-component system provided by this invention to determine the vapor-liquid equilibrium phase diagram of ethanol and n-propanol:

[0038] 1. Boiling point test of pure liquids, taking ethanol as an example: The testing apparatus is as follows: Figure 2As shown, a balloon 6 containing a small amount of air is connected to the third port 243. Pure ethanol is poured into the flask, and the thermostat is set to 85 degrees Celsius (higher than the boiling point of the pure liquid under standard atmospheric pressure). The stirrer and heater are turned on. When the temperature stabilizes at approximately 78 degrees Celsius, the temperature reading is recorded as the boiling point of ethanol. The boiling point of n-propanol is determined using the same method.

[0039] 2. Boiling points of ethanol and n-propanol with different compositions and their corresponding gas-liquid compositions: Experimental setup as follows Figure 2 As shown (where the states of the two four-way valves of the gas phase quantitative sampling component are as follows) Figure 3 As shown, both four-way valves are in the first state. A balloon 6 containing a small amount of air is connected to the third port 243. A sample to be tested (ethanol concentration approximately 80%, the remainder being n-propanol) is added to the flask (to more than 1 / 2 full). The temperature is set to 83°C. The stirrer and heater are turned on. When the temperature is maintained at 83°C, the pressure reading of the pressure gauge is recorded. After about 10 minutes, the gas phase composition is measured: Rotate the port switching valve of the second four-way valve to change the second four-way valve to the second state, that is, the first port 241 and the second port 242 are connected, and the third port 243 and the fourth port 244 are connected, as shown. Figure 4 As shown, the metering loop is now isolated from the system. Then, by rotating the interface switching valve of the first four-way valve, the first four-way valve is switched to its second state, i.e., interface 141 and interface 242 are connected, and interface 3143 and interface 4144 are connected, as shown. Figure 5 As shown, this is the injection state. The chromatographic carrier gas enters the chromatographic column for detection through interface 2 142, interface 1 141, first interface 241, second interface 242, fourth interface 144, and third interface 143. After the injection is complete, rotate the interface switching valves of the two four-way valves to return them to the first state. At this time, the quantitative loop is reconnected to the two-component system, and the chromatographic detection result is the gas phase composition at 83℃. After a few minutes, switch the gas phase quantitative sampling component from the normal state to the pre-injection state and then back to the injection state, and re-detect the gas phase composition. Repeat this process three times. If the gas phase composition does not change in the three detections, the system can be considered to have reached equilibrium. Then, using headspace sampling, the liquid sample is sampled and analyzed using gas chromatography or a refractometer. The detection result is the liquid phase composition at 83℃. The headspace sampling port has a rubber cap to ensure that the gas does not leak out.

[0040] The temperatures were then set to 85℃, 87℃, 89℃, 91℃, 93℃, and 95℃ respectively, and the gas phase composition and liquid phase composition at the given temperatures were measured using the method described above. The measured results are closer to the theoretical calculation results than those obtained by existing conventional methods, indicating that the in-situ testing device for the gas-liquid equilibrium phase diagram of the two-component system provided by this invention has better experimental performance.

[0041] This invention provides an in-situ testing device for gas-liquid equilibrium phase diagrams of two-component systems, which can eliminate long-standing contradictions in physical chemistry theory and experimental design, solve core problems in physical chemistry experimental teaching, improve experimental quality, overcome the design limitations of the experiment under existing experimental device systems, eliminate the interference of gas-phase condensate on the system, and make the experimental device conform to the experimental principle.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system, characterized in that, The system includes a gas-liquid equilibrium vessel (1), a gas phase quantitative sampling component, a liquid phase sampler, a thermostat, and a gas chromatograph (2). The gas-liquid equilibrium vessel (1) and the gas phase quantitative sampling component are both placed inside the thermostat. The gas-liquid equilibrium vessel (1) has a gas phase sampling port and a liquid phase sampling port. The gas phase sampling port is connected to the gas phase quantitative sampling component. The liquid phase sampling port allows the liquid phase sampler to be inserted into the gas-liquid equilibrium vessel (1) to draw liquid phase samples. The gas chromatograph (2) is connected to the gas phase quantitative sampling component through a carrier gas system. The gas phase quantitative sampling component includes a quantitative loop tube (3), a first four-way valve (4), and a second four-way valve. (5) and balloon (6), the first four-way valve (4) has its interface one (141) and interface four (144) connected to the two ports of one access point of the quantitative loop tube (3), the first interface (241) and the second interface (242) of the second four-way valve (5) are connected to the two ports of the other access point of the quantitative loop tube (3), the first four-way valve (4) is connected to the carrier gas system through interface two (142) and interface three (143), and the third interface (243) and the fourth interface (244) of the second four-way valve (5) are connected to the balloon (6) and the gas phase sampling port respectively.

2. The in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system according to claim 1, characterized in that, The thermostat is a constant temperature water bath device, which includes a water bath tank (7), a stirrer (8), a heater (9), and a thermocouple (10).

3. The in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system according to claim 1, characterized in that, The thermostat is a constant temperature hot air circulating oven.

4. The in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system according to claim 1, characterized in that, The gas-liquid balance vessel (1) is a flask. The liquid phase sampling port is the top opening of a liquid phase sampling tube that is vertically located at the top of the flask and communicates with the inside of the flask. A rubber cap (11) is sealed at the liquid phase sampling port. The liquid phase sampler has a sampling needle that can pierce the rubber cap (11) and enter the flask to take a sample.

5. The in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system according to claim 4, characterized in that, The gas sampling port is the opening at the end of the gas sampling tube away from the flask, the gas sampling port is connected to the top of the flask, and a barometer (12) is connected to the gas sampling tube.

6. The in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system according to claim 1, characterized in that, The carrier gas system includes a carrier gas cylinder (13) and a carrier gas tube. The two ends of the carrier gas tube are connected to the gas outlet of the carrier gas cylinder (13) and the sample inlet of the gas chromatograph, respectively. The middle part of the carrier gas tube is connected to the second interface (142) and the third interface (143) of the first four-way valve (4).

7. The in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system according to claim 1, characterized in that, The capacity of the quantitative loop tube (3) is 2-5 mL.

8. The in-situ testing apparatus for gas-liquid equilibrium phase diagrams of a two-component system according to any one of claims 1 to 7, characterized in that, The first four-way valve (4) and the second four-way valve (5) are manual valves or power valves.

9. The in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system according to claim 8, characterized in that, When the first four-way valve (4) and the second four-way valve (5) are manual valves and the thermostat is a constant temperature water bath device, the manual valve is immersed in the water bath of the constant temperature water bath device, and the adjusting handle of the manual valve is above the water bath liquid surface.

10. The in-situ testing device for gas-liquid equilibrium phase diagrams of a two-component system according to claim 8, characterized in that, The quantitative loop tube (3) is a glass tube, plastic tube, stainless steel tube or composite material tube.

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