CN100373150C - A gas solubility tester in liquid - Google Patents

Abstract

The invention discloses a gas solubility tester in liquid. The stirring blade is immersed in the experimental liquid, the stirring blade is connected with the torque motor through the motor shaft, the piston is installed in the cylinder, and the upper end of the piston is connected with the screw rod, and the cylinder is placed in a precision constant temperature water bath with temperature display; the air source is respectively connected with the The exhaust pipe is connected with the precision pressure gauge, and the precision pressure gauge is connected to the inner cavity of the cylinder through the axial hole of the piston. The invention converts the rotary motion of the screw rod into the axial movement of the cylinder piston, realizes the control of the gas phase pressure in the contact chamber with the liquid, uses a precision constant temperature water bath to make the instrument obtain accurate ambient temperature, and accurately measures the displacement of the piston before and after the experiment And the gas phase pressure parameters in the chamber, the gas state equation can be used to calculate the amount of gas remaining above the liquid before and after the experiment, and the difference is the amount of gas dissolved in the liquid. It is suitable for the measurement of saturated gas content of various high and low viscosity fluids; it can measure the gas solubility in liquids under low pressure, high pressure, low temperature and high temperature.

Description

A gas solubility tester in liquid

technical field

The invention relates to the field of measuring gas content in liquids, in particular to a gas solubility tester in liquids.

Background technique

The gas solubility testers currently used in liquid mostly use the volumetric method to measure the solubility of gas in liquid. The gas enters the burette from the gas circuit switch through the capillary tube and then pours into the liquid container. The volume of the dissolved gas before and after the experiment is measured by the burette. The change of the pressure difference can be calculated by the height difference between the two mercury surfaces in the burette, ignoring the gas circuit switch and the volume in the capillary, the volume difference measured by the burette before and after the experiment is the volume of the dissolved gas in the liquid, through the gas state equation, The amount of dissolved gas was corrected from the pressure difference before and after the experiment. For the measurement of gas solubility in liquid under high pressure, a magnetic pump capable of pressurization, high-pressure resistant pipelines and pressure gauges are required. The liquid circulates continuously under high pressure and dissolves the gas. After reaching the gas-liquid phase equilibrium, a part is taken out through the sampler. For a liquid sample, the volume of gas released from the sample is measured by a burette, and the remaining gas in the sample is directly measured by a gas chromatograph.

Figure 1 is a schematic diagram of the structure of a known tester capable of measuring the solubility of gas in a low-pressure liquid. It is mainly composed of: exhaust pipe 1, air source 3, burette 20, constant temperature air bath 21, absorber 22 with electromagnetic stirring and solvent injection, gas circuit switch 2, pressure gauge 9, capillary 23, etc. The temperature of burette 20 and absorber 22 is controlled by constant temperature air bath 21. During the test, the gas from gas source 3 enters burette 20 through capillary 23, and the volume in the burette is measured under atmospheric pressure. Neglecting the capillary 23 and the volume of the space above the solvent, the gas from the buret 20 enters through the capillary 23 and contacts with the solvent, and electromagnetically stirs until the gas-liquid phase reaches equilibrium. The gas pressure in the absorption process is measured by the difference between the two mercury levels in the burette, and can also be measured by the manometer 9 simultaneously. When the absorption reaches phase equilibrium, the remaining volume of gas in the burette can be measured at atmospheric pressure.

FIG. 2 is a structural schematic diagram of another known tester capable of measuring gas solubility in liquids under high pressure. Mainly composed of: burette 20, gas circuit switch 2, exhaust pipe 1, collected gas 29, gas circuit 28 leading to the gas chromatograph, gas storage container 27, high-pressure liquid level 25, sampler 24, constant temperature air bathroom 21 , magnetic pump 26 and other components.

The measurement principle of the gas solubility tester in liquid under high pressure is somewhat similar to that shown in Figure 1. Compared with increasing the sampler 24 and the magnetic pump 26 etc., the pipeline adopts devices that can withstand high pressure. The liquid circulates continuously under high pressure through the magnetic pump, and after fully mixing and dissolving with the gas in the gas storage container 27, the gas-liquid phase equilibrium is reached. Sampling is carried out by a sampler 24 , and the gas 29 dissolved under high pressure is released from the sample at atmospheric pressure and collected in the burette 20 , and the residual gas in the liquid is analyzed by a gas chromatograph.

For the existing gas solubility testers in liquids, there are mainly three deficiencies: First, different measuring instruments need to be used to measure the gas solubility in liquids under low pressure and high pressure, resulting in more measuring equipment. Secondly, the composition of measuring instruments is complex, the manufacturing technology is difficult and the cost is high. Thirdly, ignoring the volume of the space above the solvent, the pipeline, etc., and the inability to determine the influence of temperature changes on the volume of the container and the measurement accuracy of the instrument will lead to large errors in the measurement results.

Contents of the invention

The purpose of the present invention is to provide a gas solubility tester in liquid, which is suitable for gas solubility test under low pressure and high pressure, and can also calculate the influence of factors such as temperature change and pipeline volume on the measurement results, and obtain relatively accurate measurement result.

The technical solution adopted by the present invention to solve its technical problems is: the bottom of the cylinder body is equipped with stirring blades, the stirring blades are immersed in the experimental liquid, the stirring blades are connected with the torque motor assembled outside the bottom of the cylinder body through the motor shaft, The motor shaft is equipped with a rotary seal, the cylinder is equipped with a piston, and one or more sealing rings are installed on the piston, the piston is located above the experimental liquid, the upper end of the piston is connected with the screw, and the screw sleeve connected with the screw is fixed on the top of the cylinder. The end face and the cylinder body are placed in a precision constant temperature water bath with temperature display; the air source is connected to the exhaust pipe and the precision pressure gauge through the second and third air circuit switches after passing through the first gas circuit switch, and the precision measurement The pressure gauge communicates with the air pipe and the axial through hole on the piston, and is connected to the inner cavity of the cylinder body.

The beneficial effect that the present invention has compared with background technology is:

1. Turn the screw to make the piston move axially in the cylinder, so as to realize the pressure control (pressurization or decompression) of the gas to be dissolved above the liquid level in the cylinder. The system has few components, simple structure and low cost .

2. The cylinder body made of corrosion-resistant metal material is soaked in a precision water bath with temperature display, so that the cylinder body and the liquid and gas in the cylinder body can reach a uniform and stable temperature in a short period of time. Through precise pressure and Piston displacement measurement, using the gas state equation, can accurately obtain the amount of dissolved or precipitated gas in the liquid before and after the experiment.

3. The shape and position of the cylinder and piston made of corrosion-resistant metal have accurate dimensions. Through the material expansion coefficient, the exact value of the shape and position of the cylinder and piston at different temperatures can be calculated. Taking it into account in the experimental measurement data makes the experimental measurement results more accurate.

Therefore, it can be used to measure the saturation solubility of air, nitrogen, ammonia and other gases in various liquids. It is suitable for the measurement of saturated gas content of various high and low viscosity fluids; it can measure the gas solubility in liquids under low pressure, high pressure, low temperature and high temperature.

Description of drawings

Fig. 1 is the structure schematic diagram of known a kind of measurable gas solubility tester in low-pressure liquid;

Fig. 2 is a structural principle diagram of another tester capable of measuring gas solubility in liquid under high pressure;

Fig. 3 is a schematic diagram of the structure of the gas solubility tester in liquid according to the present invention.

In the figure: 1. Exhaust pipe, 2. Air circuit switch, 3. Air source, 4. Precision constant temperature water bath with temperature display, 5. Cylinder body, 6. Sealing ring, 7. Piston, 8. Air pipe, 9 , precision pressure gauge, 10, screw sleeve, 11, screw rod, 12, stopper, 13, bolt, 14, gas chamber, 15, experimental liquid, 16, stirring blade, 17, rotary seal, 18, torque motor , 19, sealing cover, 20, burette, 21, constant temperature air bathroom, 22, absorber with electromagnetic stirring and injected solvent, 23, capillary tube, 24, sampler, 25, high-pressure liquid level instrument, 26, magnetic pump, 27, Gas storage container, 28, the gas path leading to the gas chromatograph, 29, the collected gas.

Detailed ways

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

As shown in Figure 3, the present invention is equipped with stirring vane 16 in the bottom of cylinder body 5, and stirring vane 16 is immersed in the experiment liquid 15, and stirring vane 16 communicates with the torque motor 18 that is assembled outside the bottom of cylinder body 5 through motor shaft. connection, the rotary seal 17 on the motor shaft acts as a seal, and separates the inner cavity of the cylinder body 5 from the outside atmosphere. A piston 7 is housed in the cylinder body 5, and the piston 7 is located above the experimental liquid 15. One or A plurality of sealing rings 6, the upper end of the piston 7 is connected with the screw rod 11, the bolt 13 and the stopper 12 fix the lower end of the screw rod 11 in the inner hole of the upper end surface of the piston 7, and the screw sleeve 10 connected with the screw rod 11 is fixed in the cylinder The upper end surface of the body 5, the cylinder body 5 is placed in the precision constant temperature water bath 4 with temperature display; the gas source 3 passes through the first gas circuit switch 2, and then passes through the air pipe 8, and the second and third gas circuit switches 2 are respectively connected with the The exhaust pipe 1 is connected to the precision manometer 9, and the precision manometer 9 communicates with the axial through hole on the air pipe 8 and the piston 7, and is connected to the inner cavity of the cylinder body 5.

Through the gas pipe 8, the exhaust pipe 1, the gas source 3, the precision manometer 9, the gas chamber 14 and the chamber of the experimental liquid 15 are connected together, and a gas circuit switch 2 is also connected between the two components for Connect or disconnect the gas circuit, the precision manometer 9 accurately measures the air pressure inside the gas chamber 14 and the pipeline, and the sealing ring 6 acts as a seal, which separates the chamber where the gas chamber 14 and the experimental liquid 15 are located from the outside atmosphere Separated, the precision constant temperature water bath 4 with temperature display can make the cylinder body components, experimental gas and liquid in a constant temperature environment, the gas source 3 can provide the gas dissolved in the experimental liquid 15, and turn the screw rod 11 to make the piston 7 in the cylinder body 5 for axial movement to pressurize or decompress (vacuumize) the chamber where the gas chamber 14 and the experimental liquid 15 are located.

Referring to Figure 3, before the experiment, put the instrument into the precision constant temperature water bath 4 with temperature display, remove the screw sleeve 10 and the connecting pipeline, take out the screw rod 11 and the piston 7, and inject the measured volume into the cylinder 5 The experimental liquid 15, and then restore the piston, install the screw sleeve, connecting pipeline and screw rod, measure and record the displacement from the upper end surface of the piston to the upper end surface of the cylinder body, when the size of the piston and cylinder body is known, Calculate the volume above the liquid level in the cylinder. If it is necessary to measure the gas solubility of the liquid under negative pressure, open the gas path connecting the gas source 3 and the experimental liquid 15, ventilate the gas chamber 14 above the liquid, close the gas path, and turn the screw to make the piston move upwards. and the gas chamber 14 above the liquid to decompress, and record the temperature, pressure and piston displacement. After a long time, the gas-liquid phase reaches equilibrium, and the gas-phase pressure above the liquid surface gradually decreases and becomes stable at a certain value. Measure the pressure at this time, the amount of dissolved gas can be calculated from the gas state equation, and divided by the volume of the liquid, the gas solubility of the liquid can be obtained under the pressure and temperature environment. Power is supplied to the torque motor 18, and the torque motor 18 drives the stirring blade 16 to rotate, which can shorten the time for the gas-liquid phase to reach equilibrium, thereby shortening the time spent on the experiment.

The formula for calculating the number of moles of dissolved gas is as follows:

$\mathrm{<span\; class="notranslate">\; \&Delta;G</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; RT</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="V"\; filenames="C20061005381900071.png,C20061005381900081.png"\; state="\{\{state\}\}">V</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="RT"\; filenames="C20061005381900071.png,C20061005381900081.png"\; state="\{\{state\}\}">RT</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</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>$

In the formula: ΔG---the dissolved amount of gas; V ₀ , v ₁ --- respectively the gas volume before and after the experiment; p ₀ , p ₁ --- respectively the pressure of the gas above the liquid surface before and after the experiment; R-- -Universal constant of dissolved gas; T ₀ , T ₁ --- respectively the ambient temperature before and after the experiment.

If it is necessary to measure the gas solubility of the liquid under high pressure, after ventilation, the screw rod needs to be reversely rotated to pressurize the liquid and the gas chamber 14 above the liquid. If it is necessary to measure the gas solubility of a liquid under a certain pressure, the pressure in the gas chamber 14 needs to be adjusted intermittently during the experiment, so that the gas phase and the liquid phase are balanced and the pressure is maintained at the required pressure.

After the test is over, turn on the gas circuit switch, release the gas in the gas chamber 14 above the test liquid 15, remove the screw sleeve 10 and the connecting pipeline, lift the screw 11 to take out the piston 7, pour the liquid in the cylinder 5 Put it into the waste liquid bottle, clean the piston, cylinder and pipeline parts, and reinstall them to the original position.

The above specific embodiments are used to explain the present invention, rather than to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modification and change made to the present invention will fall into the protection scope of the present invention.

Claims (1)

1. a gas solubility tester in a liquid is characterized in that: a stirring blade (16) is housed in the bottom of the cylinder body (5), and the stirring blade (16) is immersed in the experimental liquid (15), and the stirring blade (16) ) is connected with the torque motor (18) assembled outside the bottom of the cylinder body (5) through the motor shaft, the motor shaft is equipped with a rotary seal (17), the cylinder body (5) is equipped with a piston (7), and the piston (7) One or more sealing rings (6) are installed on the top, the piston (7) is located above the experimental liquid (15), the upper end of the piston (7) is connected with the screw mandrel (11), and the screw sleeve (10) connected with the screw mandrel (11) ) is fixed on the upper surface of the cylinder body (5), and the cylinder body (5) is placed in a precision constant temperature water bath (4) with temperature display; after the gas source (3) passes through the first gas circuit switch (2), The second and third air circuit switches (2) are respectively connected to the exhaust pipe (1) and the precision manometer (9), and the precision manometer (9) communicates through the air pipe and the axial through hole on the piston (7) , into the inner cavity of the cylinder (5).

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