CN105806738A - Variable-volume pressure fixing device and method for measuring solubility of gas in liquid - Google Patents

Abstract

The invention discloses a variable volume and constant pressure device and method for measuring the solubility of gas in liquid, comprising a gas sample bottle, a gas chamber, a balance chamber, a constant temperature tank with a magnetic stirrer, a pressure sensor, a thermometer, a gas chromatograph, Pressure reducing valve, pressure control cylinder, vacuum pump, real-time data acquisition system. The gas chamber is used to control and calculate the injection volume of the gas in the balance chamber; the balance chamber has a visual window and a moving piston, which can observe the liquid level and adjust its internal pressure; the pressure control gas cylinder can be adjusted by adjusting the moving piston Keep the pressure in the balance chamber constant. The invention realizes the measurement of the solubility of gas pure substance and mixture in liquid under constant pressure through the method of stabilizing the internal pressure of the balance chamber by an external large-capacity gas cylinder, and can avoid the deviation of dissolution balance caused by sampling.

Description

A variable volume and constant pressure device and method for measuring the solubility of gas in liquid

technical field

The invention belongs to the technical field of measuring fluid thermophysical properties, and relates to a device and method suitable for measuring the solubility of gas pure substances and mixtures in liquids.

Background technique

Almost all industrial processes involving gas-liquid contact involve the dissolution of gas in liquid. The solubility of gas in liquid is the basic data necessary for the design of these industrial processes. The measurement methods of gas solubility in liquid mainly include gravity balance method, quartz crystal microbalance method, weighing method, gas chromatography, bubble point method, equal volume saturation method, etc.

Among many measurement methods, the equal volume saturation method is widely used due to its advantages of simple operation, high precision and high output efficiency. However, due to the lack of design, it is difficult to measure the solubility of gas under the specified pressure by the equal volume saturation method, and it is difficult to reproduce. In addition, when sampling the gas, it will cause pressure fluctuations, destroy the original dissolution balance, cause changes in the composition of the mixed gas, and make multiple measurement results inconsistent, so it is not suitable for the measurement of the solubility of mixed gases in liquids.

Contents of the invention

The purpose of the present invention is to provide a variable volume and constant pressure device and method for measuring the solubility of gas in liquid, to solve the problems existing in the equal volume saturation method, and to provide technical support for obtaining gas solubility data required in the field of energy and chemical industry.

In order to achieve the above object, the present invention adopts the following technical solutions:

A variable volume and constant pressure device for measuring the solubility of gas in liquid, the device includes a gas chamber, a balance chamber, a constant temperature tank and a pressure control cylinder, the gas chamber and the balance chamber are arranged in the constant temperature tank, and a piston is arranged in the balance chamber , the piston divides the balance chamber into two parts: the dissolved gas sub-chamber above the piston and the high-pressure sub-chamber below the piston. The volume of the pressure-controlling gas cylinder is larger than that of the balance chamber. The pipeline of the sensor is connected with the high-pressure sub-chamber, and the balance chamber is provided with a visual window for observing the change of the piston position, a sampling valve connected with the dissolved gas sub-chamber, and a sample valve for detecting the dissolved gas sub-chamber. A temperature sensor for the temperature in the chamber, the gas chamber is connected to the balance chamber through the sampling valve, and a sensor for detecting the temperature and pressure in the gas chamber is arranged on the gas chamber.

The upper surface of the piston is parallel to the bottom of the balance chamber, which is convenient for calibration.

A magnetic stirrer is arranged on the constant temperature tank, and a magnetic rotor driven by the magnetic stirrer is arranged in the dissolved air sub-chamber of the balance chamber.

The device also includes a first valve, a second valve, a third valve, a fifth valve, a vacuum pump and a gas sample bottle, the third valve is connected to the gas cavity, the first valve is arranged on the connecting pipeline between the vacuum pump and the third valve, The second valve is arranged on the connecting pipeline between the gas sample bottle and the third valve, and one end of the fifth valve communicates with the high-pressure sub-chamber of the balance chamber.

The device also includes a gas chromatograph, a fourth valve, and a sampling valve connected to the dissolved gas sub-chamber of the balance chamber, the gas chromatograph is connected to the gas chamber through the fourth valve, and the gas chromatograph is connected to the balance chamber through the sampling valve. cavities connected.

The device also includes a data acquisition system, the temperature sensor, the pressure sensor and the sensor for detecting the temperature and pressure in the gas chamber are respectively connected with the data acquisition system.

A method for measuring the solubility of a gas in a liquid using the above-mentioned device, comprising the following steps:

1) Add a liquid with a volume of V _l and a molar mass of n _l into the gas-dissolved sub-chamber of the balance chamber, and then the gas chamber, the gas-dissolved sub-chamber of the balance chamber, the high-pressure sub-chamber, and the Vacuumize the connecting pipeline;

2) After step 1), a certain volume of target gas is filled and sealed in the gas cavity, and then the temperature and pressure in the gas cavity are detected;

3) Fill and seal part of the target gas in the gas chamber into the dissolved gas sub-chamber of the balance chamber, and then detect the temperature and pressure in the gas chamber;

4) After step 3), adjust the temperature value of the constant temperature tank to make the temperature in the balance chamber reach the target temperature, and then control the pressure in the high-pressure sub-chamber of the balance chamber to reach the target pressure through the pressure reducing valve, and ensure that the target pressure is less than the control temperature. The pressure of the gas in the gas cylinder, when the piston is no longer moving, detect the temperature and pressure in the dissolved gas sub-chamber of the balance chamber, and measure the height of the piston through the visible window, and obtain the dissolved gas sub-chamber of the balance chamber according to the height of the piston The total volume V _E of liquid and undissolved target gas in the chamber; when the piston no longer moves, the pressure in the dissolved gas sub-chamber of the balance chamber is equal to the pressure measured by the pressure sensor;

5) Calculation of solubility

According to step 2) and step 3) the temperature and the pressure in the gas chamber detected and the volume of the gas chamber are calculated from the molar quantity Δn of the gas that is filled into the dissolved gas sub-chamber of the balance chamber from the gas chamber; according to the balance of step 4) detection The temperature and pressure in the dissolved gas sub-chamber of the cavity and the volume of the undissolved target gas in the balanced gas sub-chamber V _g =V _E -V _l , calculate the molar amount n _g of the undissolved target gas, Calculate the molar amount of the target gas dissolved into the liquid from _Δn and ng as according to and n _l calculate the mole fraction x of the target gas dissolved into the liquid at the target temperature and pressure.

In the step 4), the liquid is stirred by the magnetic rotor arranged in the dissolved air sub-chamber of the balance chamber until the piston stops moving.

If the target gas is a mixed gas, the following two detections for the target gas will also be carried out; the first time is in step 2), utilizing a gas chromatograph to detect the composition of the target gas charged into the gas chamber; the second time In step 4), the composition of the undissolved target gas is detected by a gas chromatograph; the composition of the target gas dissolved in the liquid is obtained based on two detections of the target gas.

The Henry constant of the target gas in an infinitely diluted solution is calculated according to x.

The beneficial effects of the present invention are reflected in:

The gas chamber described in the present invention is used to control and calculate the sample amount of gas in the balance chamber; the balance chamber has a visual window and a piston, which can observe the height of the piston and adjust its internal pressure; Keep the pressure in the balance chamber constant. The invention realizes the measurement of the solubility of the gas pure substance and the mixture in the liquid under constant pressure through the method of stabilizing the internal pressure of the balance chamber by an external large-capacity gas cylinder, and can avoid the deviation of the dissolution balance caused by sampling.

The invention not only can adjust the pressure of the balance chamber in real time through the pressure control gas cylinder and the piston, but also can eliminate the pressure change caused by gas dissolution and sampling, realize isobaric measurement and improve the accuracy of solubility measurement results.

By connecting the gas chromatograph, the invention is not only applicable to the measurement of the solubility of pure gas in liquid, but also suitable for the measurement of the solubility of mixed gas in liquid.

Description of drawings

Fig. 1 is the structural representation of gas solubility measuring device;

Fig. 2 is a structural design diagram of the balance chamber; wherein, (a) is a top view, and (b) is a side view;

Figure 3 is a cross-sectional view of the balance chamber;

Figure 4 is a structural design drawing of the gas cavity;

In the figure: 1. Gas sample bottle; 2. Vacuum pump; 3. The first valve; 4. The second valve; 5. The third valve; 6. Gas chromatograph; 7. Gas cavity; 8. Platinum resistance thermometer; 9. The fourth valve; 10. Injection valve; 11. Sampling valve; 12. Balance chamber; 13. Constant temperature tank; 14. Data acquisition system; 15. Pressure sensor; 16. Fifth valve; 17. Pressure reducing valve; 18. Pressure control gas cylinder; 19. Fixing bolt; 20. Thermometer socket; 21. Top cover; 22. Visual window; 23. Pressure control gas cylinder interface; 24. Gasket; 25. Magnetic rotor; 26. Piston; 27. Lens fixing ring ; 28, lens; 29, O-ring; 30, bracket; 31, pressure sensor installation interface; 32, gas chamber cavity; 33, air outlet; 34, air inlet.

detailed description

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

Referring to Fig. 1, the variable volume and constant pressure device for measuring the solubility of gas in liquid according to the present invention mainly includes: gas sample bottle 1; vacuum pump 2, first valve 3, second valve 4, third valve 5, gas chromatograph Instrument 6, gas chamber 7, temperature sensor, fourth valve 9, sampling valve 10, sampling valve 11, balance chamber 12, constant temperature tank 13, data acquisition system 14, pressure sensor, fifth valve 16, pressure reducing valve 17 and Control pressure cylinder 18. The gas chamber 7 is connected with the gas sample bottle 1 , the vacuum pump 2 and the balance chamber 12 through stainless steel pipes, and is used for measuring the amount of gas input into the balance chamber 12 . The gas chamber 7 and the balance chamber 12 are placed in a constant temperature tank 13 for temperature control (such as utilizing a water bath to keep the temperature constant). The constant temperature tank 13 has a transparent window to facilitate the observation of the height of the liquid level in the balance chamber 12; the bottom of the constant temperature tank 13 has a magnetic stirrer device, and the liquid in the balance chamber 12 is stirred by the magnetic rotor 25 to accelerate gas dissolution. The pressure-regulating gas cylinder 18 is connected with the balance chamber 12 through a stainless steel pipe, and the pressure inside the balance chamber 12 is controlled by a pressure-reducing valve 17 and a moving piston 26 to ensure its stability. The temperature inside the gas chamber 7 and the balance chamber 12 is measured by temperature sensors (platinum resistance thermometers 8 ) inserted into the walls of their containers. The pressure inside the gas chamber 7 is measured by a pressure sensor mounted on its top cover 21 . The pressure inside the balance chamber 12 is obtained by measuring the pressure at the outlet of the pressure reducing valve 16 with the pressure sensor 15. The temperature and pressure data are collected by the data acquisition system 14 for solubility calculation. The data acquisition system is built on the basis of a Keithley2007 digital multimeter and compiled by Labview program control. The composition of the gas sample (in the gas chamber) and the composition of the dissolved and balanced gas (in the equilibrium chamber) are measured by a gas chromatograph 6 .

Referring to Fig. 1, Fig. 2 and Fig. 3, the balance chamber 12 includes a balance chamber body and a top cover 21, the top cover 21 is connected with the balance chamber body by fixing bolts 19, and the joint is sealed by a gasket 24, and the balance The top cover of the chamber 12 is equipped with a sampling valve 10, a sampling valve 11, and a thermometer socket 20. A movable piston 26 is arranged in the balance chamber cavity, and the piston 26 divides the balance chamber 12 into upper and lower parts. The O-ring 29 ensures that the upper and lower parts of the separation are not connected to each other. The upper surface of the piston is parallel to the bottom of the balance chamber. The upper part of the balance chamber (the part above the piston) is used to dissolve the gas sample by the liquid. The magnetic rotor 25 driven by the stirrer can be used to accelerate gas dissolution. The lower part of the balance chamber (the part below the piston) is used as a closed high-pressure chamber. The high-pressure chamber is connected to the pressure-controlling gas cylinder 18 through a stainless steel pipeline connected to the pressure-controlling gas cylinder interface 23, and a pressure reducing valve 17 and a pressure sensor 15 are installed on the connecting pipeline between the pressure-controlling gas cylinder 18 and the high-pressure chamber, and the outlet of the pressure-controlling gas cylinder The pressure of the pressure is regulated by the pressure relief valve 17, and one end of the fifth valve 16 is connected on the corresponding pipeline between the pressure relief valve 17 and the pressure control gas cylinder interface 23; the volume of the pressure control gas cylinder 18 should be much larger than the balance chamber 12 (at least more than 100 times), so that the volume change of the upper part of the balance chamber has a negligible influence on the pressure of the pressure-controlling gas cylinder 18, thereby ensuring that the pressure of the upper part of the balance chamber is constant. In order to prevent the piston 26 from blocking the pressure-regulating gas cylinder interface 23, the pressure-regulating gas cylinder interface 23 is usually located on the lower side of the high-pressure chamber, and a height slightly higher than that of the pressure-regulating gas cylinder is provided in the high-pressure chamber. The bracket 30 of the interface 23 can prevent the piston 26 from moving down to the position of the interface 23 of the pressure-regulating gas cylinder. The balance cavity has a high-pressure visible window 22. The high-pressure visible window includes a lens fixing ring 27 embedded in the balance cavity cavity and a lens 28 arranged in the lens fixing ring 27. The high-pressure visible window is used for observing the liquid level position.

1 and 4, the gas chamber 7 includes a gas chamber body 32 and a top cover 21, the top cover 21 and the gas chamber body 32 are connected by fixing bolts 19, and the joint is sealed by a gasket. An air inlet 34 , an air outlet 33 , a thermometer socket 20 and a pressure sensor installation interface 31 are provided.

The air inlet 34 is respectively connected to the vacuum pump 2 and the gas sample bottle 1 by a stainless steel pipeline with a valve (the third valve 5), and the gas sample bottle 1 and the vacuum pump 2 are respectively connected to the stainless steel pipeline by being provided with a valve (the second valve 4 and The pipelines of the first valve 3) are connected. Gas outlet 33 is connected with sampling valve 10, meanwhile, gas outlet 33 is connected with gas chromatograph 6 by the stainless steel pipeline that valve (the 4th valve 9) is installed, and gas chromatograph 6 is connected with sampling valve 11 simultaneously.

The method for using the above-mentioned variable volume and constant pressure device for measuring the solubility of gas in liquid comprises the following steps:

(1) Utilize the weighing method to calibrate the volume of the pipeline in the balance chamber 12 and the gas chamber 7 and the dotted line inner area in Fig. 1, and obtain the change of the volume above the balance chamber piston when the piston 26 moves, and the calibration working medium is water.

(2) Check the tightness of the experimental system. Use the vacuum pump 2 to evacuate the experimental system (including the part above the piston 26 in the balance chamber 12, the gas chamber 7, and the corresponding connecting pipelines in the dotted line box in Figure 1) to a vacuum below 1kPa. After waiting for 1 hour, if the system pressure remains the same If it is lower than 1kPa, then use the gas sample bottle 1 to fill the gas with a pressure of 10MPa. After 1 hour, if the system pressure change is lower than 1kPa, it is considered that the sealing of the system is good. The air pressure is measured from the pressure on the top cover of the gas chamber. Pressure Sensor.

(3) Put the target liquid (using ionic liquid with high boiling point to avoid liquid volatilization during vacuuming) into the reagent bottle, and use a precision electronic balance to measure the quality of the reagent bottle. A certain amount of liquid is poured into the balance chamber 12 (the part above the piston), and the mass of the reagent bottle is measured again to obtain the mass of the liquid in the balance chamber.

(4) Reconnect the balance chamber 12 to the system, make the second valve 4 closed, open the first valve 3, the third valve 5 and the injection valve 10, and connect the fifth valve 16 (open state) to the vacuum pump 2. Vacuumize the experimental system and high-pressure chamber (absolute pressure lower than 1kPa).

(5) Close the first valve 3, the fifth valve 16 and the sampling valve 10, open the second valve 4, make the gas sample in the gas sample bottle 1 be charged in the gas chamber 7, and wait for the temperature and pressure of the gas chamber 7 to stabilize Finally, record the temperature and pressure of the gas chamber, and close the second valve 4 and the third valve 5 at this time. Then open the sampling valve 10, input a certain amount of gas sample into the balance chamber 12, close the sampling valve 10, and record the temperature and pressure of the gas chamber 7. For the mixed gas, the gas chromatograph 6 is used to measure the composition of the gas in the gas chamber.

(6) Regulate the temperature value of the constant temperature tank 13 to the target temperature, open the pressure reducing valve 17 and control to the target pressure, and the pressure of the input gas in the balance chamber 12 (the part below the piston) will be less than the pressure of the gas in the pressure control cylinder 18, Turn on the magnetic stirrer and stir the liquid. When the piston 26 is no longer moving, the dissolution equilibrium is reached, the temperature and pressure of the balance chamber 12 are recorded, and the height of the piston 26 is measured. The gas chromatograph 6 is used to measure the composition of the remaining undissolved gas in the balance chamber 12 .

(7) Open the fifth valve 16 to release the pressure, and open the first valve 3, the third valve 5 and the sampling valve 10 to evacuate the system so that the gas sample is discharged from the experimental system, and start the next measurement.

In order to ensure the accuracy and reproducibility of the experimental results, three measurements were performed for each experimental point.

Processing method of experimental data:

Since the direct measurement results of the above-mentioned variable volume constant pressure device for measuring the solubility of gas in liquid are temperature and pressure, the measurement results need to be processed and converted into the mole fraction of gas in liquid or Henry's constant to represent the solubility of gas.

First, calculate the volume V ₁ and molar mass n _l of the liquid from the mass m, mass density ρ ₁ and molar mass M of the liquid, respectively:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; m</span>}}{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

The molar quantity Δn of gas entering the balance chamber from the gas chamber is:

Δn=n _i -n _f (3)

In the formula: n _i is the molar amount of gas in the gas chamber before the gas is input into the balance chamber; n _f is the molar amount of gas in the gas chamber after the gas is input into the balance chamber. n _i , n _f can be obtained by using the mass density ρ _i , ρ _f of the gas in the gas chamber before and after the gas is input into the balance chamber and the volume V _G of the gas chamber:

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

where M _g is the molar mass of the target gas. The mass density ρ _i , ρ _f can be calculated from the precise state equation using the temperature and pressure of the gas chamber before and after the target gas is input from the gas chamber to the balance chamber.

When the gas in the balance chamber reaches the dissolution equilibrium in the liquid, the volume of the gas part in the part above the balance chamber piston can be obtained from the volume V _E of the part above the balance chamber piston and the volume V1 _of the liquid:

V _g =V _E -V _l (6)

The molar amount of gas in the balance chamber can be obtained from the volume and mass density ρ _g of the gas part in the balance chamber:

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

The mass density ρ _g can be calculated from the temperature and pressure of the equilibrium chamber using an accurate equation of state. moles of gas dissolved in a liquid for:

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

Combining formulas (1) to (8), we get:

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

The mole fraction x of a gas dissolved in a liquid can be expressed as:

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

The Henry constant for a gas in an infinitely dilute solution can be expressed as:

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; \&Right\; Arrow;</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; m</span>}}\frac{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

f is the fugacity of the gas, calculated using the precise equation of state.

Claims (10)

1. null1. the variable volume constant pressure arrangement measuring gas dissolubility in a liquid，It is characterized in that: this device includes air chamber (7)、Counter balance pocket (12)、Temperature chamber (13) and pressure control gas cylinder (18)，Described air chamber (7) and counter balance pocket (12) are arranged in temperature chamber (13)，Piston (26) it is provided with in counter balance pocket (12)，Counter balance pocket (12) is divided into the Rong Qi sub-chamber being positioned at more than piston (26) and is positioned at piston (26) higher pressure subsidiary chamber two parts below by piston (26)，The volume of pressure control gas cylinder (18) is more than the volume of counter balance pocket (12)，Pressure control gas cylinder (18) is connected with described higher pressure subsidiary chamber by the pipeline with air relief valve (17) and pressure transducer (15)，Counter balance pocket (12) is provided with the visual window (22) for observing piston (26) change in location、The injection valve (10) that is connected with described Rong Qi sub-chamber and for detecting the temperature sensor of temperature in described Rong Qi sub-chamber，Air chamber (7) is connected with counter balance pocket (12) by described injection valve (10)，Air chamber (7) is provided with the sensor for detected gas cavity temperature and pressure.
2. 2. a kind of variable volume constant pressure arrangement measuring gas dissolubility in a liquid according to claim 1, it is characterised in that: the upper surface of described piston (26) is parallel to counter balance pocket (12) bottom.
3. 3. a kind of variable volume constant pressure arrangement measuring gas dissolubility in a liquid according to claim 1, it is characterized in that: described temperature chamber (13) is provided with magnetic stirrer, in the Rong Qi sub-chamber of described counter balance pocket (12), be provided with the magnet rotor (25) driven by magnetic stirrer.
4. 4. a kind of variable volume constant pressure arrangement measuring gas dissolubility in a liquid according to claim 1, it is characterized in that: described device also includes the first valve (3), second valve (4), 3rd valve (5), 5th valve (16), vacuum pump (2) and gaseous sample bottle (1), 3rd valve (5) is connected with air chamber (7), first valve (3) is arranged on the connecting line of vacuum pump (2) and the 3rd valve (5), second valve (4) is arranged on the connecting line of gaseous sample bottle (1) and the 3rd valve (5), one end of 5th valve (16) is connected with the higher pressure subsidiary chamber of counter balance pocket (12).
5. 5. a kind of variable volume constant pressure arrangement measuring gas dissolubility in a liquid according to claim 1, it is characterized in that: described device also includes the sampling valve (11) that gas chromatograph (6), the 4th valve (9) and the Rong Qi sub-chamber with counter balance pocket (12) are connected, gas chromatograph (6) is connected with air chamber (7) by the 4th valve (9), and gas chromatograph (6) is connected with counter balance pocket (12) by described sampling valve (11).
6. 6. a kind of variable volume constant pressure arrangement measuring gas dissolubility in a liquid according to claim 1, it is characterized in that: described device also includes data collecting system (14), and described temperature sensor, pressure transducer (15) and the sensor for detected gas chamber (7) interior temperature and pressure are connected with data collecting system (14) respectively.
7. 7. the method utilizing measurement device gas dissolubility in a liquid as claimed in claim 1, it is characterised in that: comprise the following steps:

   1) it is V by volume_l, mole be n_lLiquid add counter balance pocket (12) Rong Qi sub-chamber in, the then connecting line evacuation to air chamber (7), the Rong Qi sub-chamber of counter balance pocket (12), higher pressure subsidiary chamber and air chamber (7) Yu counter balance pocket (11)；

   2) through step 1) after, the object gas of certain volume is filled with and is closed in air chamber (7), then the temperature and pressure in detected gas chamber (7)；

   3) the partial target gas in air chamber (7) is filled with and is closed in the Rong Qi sub-chamber of counter balance pocket (12), then the temperature and pressure in detected gas chamber (7)；

   4) through step 3) after, counter balance pocket (12) interior temperature is made to reach target temperature by the temperature value of regulating thermostatic groove (13), then, the higher pressure subsidiary cavity indoor pressure being controlled counter balance pocket (12) by air relief valve (17) reaches goal pressure, and ensure that goal pressure is less than in pressure control gas cylinder (18) pressure of gas, the temperature and pressure in the Rong Qi sub-chamber of counter balance pocket (12) is detected when piston (26) no longer moves, and the height of piston (26) is measured by described visual window (22), height according to this piston (26) is balanced in the Rong Qi sub-chamber in chamber (12) liquid and the cumulative volume V of undissolved object gas_E；When piston (26) no longer moves, the pressure that the pressure in the Rong Qi sub-chamber of counter balance pocket (12) is measured equal to described pressure transducer (15)；

   5) dissolubility is calculated

   According to step 2) and step 3) volume computing of temperature and pressure in the air chamber (7) that detects and air chamber (7) is filled with the mole Δ n of the gas of the Rong Qi sub-chamber of counter balance pocket (12) from air chamber (7)；According to step 4) the volume V of undissolved object gas in the Rong Qi sub-chamber of temperature and pressure in the Rong Qi sub-chamber of counter balance pocket (12) detected and counter balance pocket (12)_g=V_E-V_l, calculate the mole n of described undissolved object gas_g, according to Δ n and n_gThe mole calculating the object gas being dissolved in liquid isAccording toAnd n_lCalculate object gas under target temperature and pressure and be dissolved into the molar fraction x in liquid.
8. 8. method according to claim 7, it is characterized in that: described step 4) in, liquid is stirred by the magnet rotor (25) that utilization is arranged in the Rong Qi sub-chamber of counter balance pocket (12), until piston (26) no longer moves.
9. 9. method according to claim 7, it is characterised in that: if object gas is mixing gas, then it is also performed to following twice detection for object gas；It is in step 2 for the first time) in, utilize gas chromatograph (6) that the composition of the object gas of insufflation gas chamber (7) is detected；Second time is in step 4) in, utilize gas chromatograph (6) that the composition of described undissolved object gas is detected；The composition of the object gas being dissolved in liquid is drawn according to twice detection for object gas.
10. 10. method according to claim 7, it is characterised in that: calculate according to x and obtain object gas Henry's constant in infinite dilute solution.