KR100747329B1 - Apparatus and method for measuring solubility of gas - Google Patents

Abstract

A gas solubility measurement device is provided to measure stepwise dissolution amount and solubility according to time passage by one time gas injection/discharge by calculating the dissolution amount from pressure difference of injected gas without putting out specimens. A gas solubility measurement device comprises a test pipe(25), a standard pipe(26), a pressure difference meter(36) and a calculation unit(41). The test pipe is a hollow tubing pipe, inserted by a specimen corresponding to solvent for solving gas, and maintains a sealing state after gas injection. The standard pipe is a tubing pipe having the same material and volume as the test pipe, and maintains the sealing state after the gas injection. The pressure difference meter measures pressure difference of the test pipe and the standard pipe in predetermined space after the gas injection. The calculation unit calculates gas solubility of the specimens based on the pressure difference data transferred from the pressure difference meter.

Description

Apparatus and method for measuring solubility of gas

1 is a configuration diagram of one embodiment of a conventional gas solubility measuring apparatus;

2 is a schematic configuration diagram of an apparatus for measuring gas solubility according to an embodiment of the present invention;

3 is a plan view of a gas solubility measuring apparatus according to an embodiment of the present invention,

4 and 5 is a front view of the gas solubility measuring apparatus according to an embodiment of the present invention,

6 is a flow chart for a gas solubility measuring method according to an embodiment of the present invention;

7a and 7b is a graph showing the results of measuring the gas solubility using the gas solubility measuring apparatus according to an embodiment of the present invention,

8 is a table showing the dissolution amount calculation of the gas solubility measuring apparatus according to an embodiment of the present invention,

9 is a table showing the relationship between the gas pressure and the density used for calculating the amount of dissolution,

10A and 10B are graphs showing results of measuring gas diffusion using a gas solubility measuring apparatus according to an embodiment of the present invention.

* Explanation of symbols on the main parts of the drawing

21: differential pressure gauge 22: external output terminal

23: differential pressure gauge needle valve 24: tubing union

25: test tube 26: reference tube

27: test tube pressure gauge 28: test tube input and output valve

29: reference pipe input and output valve 30: gas discharge valve

31: tubing pipe 32: gas injection valve

33: differential pressure valve 40: computing device

The present invention relates to a gas solubility measuring apparatus and method, and more particularly to a gas solubility measuring apparatus and method for measuring the solubility more accurately by using a change in pressure generated when the gas is dissolved.

In general, solubility measurements for gases are made using high pressure vessels capable of maintaining a constant pressure and temperature for a predetermined time. That is, a sample (for example, plastic) to be measured for solubility is put in a high pressure vessel, gas is injected, and a certain pressure and temperature are maintained for a predetermined time, and then taken out, solubility is calculated from the change in its weight.

1 is a configuration of an embodiment of a conventional gas solubility measuring apparatus.

As shown in FIG. 1, the conventional gas solubility measuring apparatus prevents gas injected into the high-pressure vessel 11 and the high-pressure vessel 11 from being made to open and close. Rubber ring, measuring device for measuring temperature and pressure inside the high pressure vessel (11) (Thermocouple (12), pressure gauge (13)), injecting gas into the high pressure vessel (11) Valve devices 14a and 14b for controlling discharge, and a high pressure vessel 11 and a pipe for connecting the gas supply device.

In order to measure the dissolution amount with respect to gas using the conventional solubility measuring apparatus, after measuring the weight of the to-be-tested object 10, it puts into the high pressure container 11 first. And after opening the valve 14a and injecting gas into the high pressure container 11, the valve 14a is locked so that the injected gas may not leak out. Then, the temperature and pressure are maintained at a constant level using the measuring devices 12 and 13.

After a predetermined time has elapsed, the valve 14b is opened, the gas inside the high pressure vessel 11 is discharged, the object 10 in the high pressure vessel 11 is taken out, and the weight increase amount is measured. And a gas melt | dissolution amount is computed by following formula (1). For reference, the solubility refers to the amount of dissolution when the dissolution amount no longer increases at a certain pressure and temperature.

Dissolution amount (wt%) = (weight increase) / (initial weight)

However, the conventional gas solubility measuring apparatus removes gas from the high pressure container 11 to measure the amount of dissolved gas (dissolved amount) dissolved in the subject 10, and then removes the subject 10 by opening the lid. In this case, the process of measuring weight is necessary.

Therefore, it is impossible to measure the initial dissolution amount in which the weight increase is insignificant, and there is a problem that only one result can be obtained even after a long experiment.

In addition, in the conventional gas solubility measuring apparatus, even if the time required to remove the gas from the high pressure vessel 11 and take out the object 10 is short as a few minutes, a large amount of gas escapes for a short time. There is a problem that can not accurately measure the diffusion degree of.

The present invention has been proposed to solve the above problems, and an object thereof is to provide a gas solubility apparatus and method for calculating the amount of dissolution from a change in injected gas pressure.

It is another object of the present invention to provide a gas solubility device and method which further performs the function of measuring the diffusivity from the increase in pressure generated as the gas diffuses after the gas solubility measurement.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The apparatus of the present invention for achieving the above object is a tubing tube with an empty inside, the test tube is inserted into the specimen corresponding to the solvent to be dissolved gas, the test tube for maintaining the sealing state after the gas injection; A reference tube that maintains a sealing state after gas injection as a tubing tube having the same material and volume as the test tube; A differential pressure gauge for measuring a differential pressure between the test tube and the reference tube at a predetermined interval after gas injection; And means for calculating gas solubility of the specimen based on the differential pressure data received from the differential pressure gauge.

Preferably, the differential pressure gauge further performs a function of measuring and displaying a differential pressure generated when gas dissolved in the test tube is diffused after the gas solubility measurement is completed and the gas of the test tube and the reference tube is discharged. can do.

More preferably, the differential pressure gauge may further perform a function of calculating a diffusion degree and displaying the difference using the differential pressure measured at predetermined intervals.

In addition, the method of the present invention, a gas injection step of maintaining a sealing state after injecting a gas to be measured for the solubility to the test tube containing the specimen and the reference tube of the same specification and material as the test tube at the same pressure; A differential pressure measuring step of measuring a differential pressure between the test tube and the reference tube at predetermined intervals; A solubility calculation step of calculating solubility from the measured differential pressure; And a gas discharge step of discharging the gas as the solubility calculation is completed.

Preferably, after the gas discharge is completed, maintaining the test tube and the reference tube in a sealed state; Measuring a differential pressure between the test tube and the reference tube at predetermined intervals; And calculating a diffusivity from the measured differential pressure.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, Figure 2 is a schematic configuration diagram of a gas solubility measuring apparatus according to an embodiment of the present invention, Figure 3 is a plan view of a gas solubility measuring apparatus according to an embodiment of the present invention, Figures 4 and 5 the present invention Front view of a gas solubility measuring apparatus according to an embodiment of the.

2 to 5, the gas solubility measuring apparatus according to an embodiment of the present invention, the differential pressure measuring unit 36, the test tube 25, the reference tube 26, the gas injection unit 35 and And a measuring unit 40.

The differential pressure measuring unit 36 is composed of a differential pressure gauge 21, a signal transmission line 22, a differential pressure gauge needle valve 23, and a tubing union 24, and the gas injection unit 35 is a test tube pressure gauge 27. , Test tube input / output valve 28, reference tube input / output valve 29, gas discharge valve 30, tubing tube 31, tubing union 24, gas injection valve 32, differential pressure valve 33 The measuring unit 40 includes a computing device 41 and a memory 42.

The differential pressure gauge 21 measures and displays the differential pressure of the test tube 25 and the reference tube 26 generated as the amount of dissolution is measured. At this time, the differential pressure of the test tube 25 and the reference tube 26 measured by the differential pressure gauge 21 is used to calculate the amount of dissolution (solubility) in the gas of the test piece 25a.

That is, the pressure of the reference tube 26 does not change over time, whereas the pressure of the test tube 25 is applied to the solvent (ie, specimen: 25a) (PP) inserted into the test tube 25 with time. As the solute (carbon dioxide) dissolves, it decreases. Using this principle, the dissolution amount (solubility) is calculated.

The differential pressure measured by the differential pressure gauge 21 is transmitted to the measuring unit 40 through the signal transmission line 22. The measuring unit 40 stores the differential pressure data received from the differential pressure gauge 21 in the memory 42, and calculates a dissolution amount (solubility) using the arithmetic unit 41. The memory 42 records a table shown in FIG. 9 in addition to the differential pressure data.

The differential pressure gauge needle valve 23 is a valve capable of opening and closing a flow path between the test tube 25 and the reference tube 26 so that the gas injected from the outside is injected into the test tube 25 and the reference tube 26 in the same manner. do. To this end, the differential pressure gauge needle valve 23 must be able to maintain a sealing while being able to withstand the pressure of the gas to be injected.

The tubing union 24 serves to connect the test tube 25 and the reference tube 26 with the differential pressure gauge 21, the test tube pressure gauge 27, and the reference tube input / output valve 29. The tubing union 24 is composed of a front ferrule, a rear ferrule, a nut and a connector, and can sufficiently withstand the pressure of the fluid used for the measurement, and can be sealed at the working pressure.

The test tube 25 is an empty tubing tube, and a specimen 25a corresponding to a solvent in which gas is dissolved is inserted into the test tube 25. The size of the test tube 25 is the same as the reference tube (26).

The reference tube 26 is an empty tubing tube and is filled with a gas to be used for measurement.

The test tube pressure gauge 27 displays the fluid pressure inside the test tube 25. The amount of dissolution can be measured only by the differential pressure gauge 21. The test tube pressure gauge 27 plays an additional role of indicating the pressure of the current state at which the measurement is made.

The test tube inlet / outlet valve 28 is a valve capable of controlling the gas injected through the gas injection valve 32 to enter and exit the test tube 25.

The reference tube inlet / outlet valve 29 is a valve capable of controlling the gas injected through the gas injection valve 32 to enter and exit the reference tube 26.

The gas outlet valve 30 is a valve capable of controlling the gas injected through the gas injection valve 32 to be discharged outward.

The tubing pipe 31 is a gas introduced from the gas injection valve 32 to the test tube inlet / outlet valve 28, the reference tube inlet / outlet valve 29 and the gas discharge valve 30 Connect to inflow.

The gas inlet valve 32 is a valve that can be controlled to inject gas to be used for measurement. Depending on the experimental purpose, various gases may be compressed and injected.

The differential pressure valve 33 is a valve capable of controlling the flow path between the test tube 25 and the reference tube 26.

On the other hand, in order to measure the gas solubility of a specific material under a given temperature and pressure conditions, the test piece 25a is first inserted into the test tube 25, and then the gas injection valve 32, the test tube input / output valve 28, and the reference tube input / output valve (29), the pressure gauge needle valve 23 is adjusted so that the gas to be tested is injected into the test tube 25 and the reference tube 26. Here, the initial pressure of the gas injected into the test tube 25 and the reference tube 26 when the injection is completed is the same.

Thereafter, as time passes, the gas is dissolved in the test piece 25a inside the test tube 25, so that a differential pressure is generated between the test tube 25 and the reference tube 26. The present invention calculates the gas dissolution amount and the gas solubility from the differential pressure of the test tube 25 and the reference tube 26 generated over time.

Hereinafter, the overall operation of the present invention will be described with reference to FIG. 6.

6 is a flowchart illustrating a gas solubility measuring method according to an embodiment of the present invention.

First, after checking whether or not the gas solubility measuring device is sealed, the specimen 25a corresponding to the solvent for which the amount of dissolution is to be measured is placed in the test tube 25 (S501). For example, if you want to measure the dissolution of carbon dioxide into PP, put the processed PP into the test tube (25). At this time, it is confirmed that the state of the differential pressure gauge 21 is the origin (0).

Subsequently, the differential pressure gauge needle valve 23, the test tube input / output valve 28, and the reference tube input / output valve 29 are opened under the temperature and pressure conditions to be tested, and the gas discharge valve 10 is locked to the test tube 25 and the reference. After the pipe 26 is blocked from the outside, the gas injection valve 32 is opened to inject a gas (for example, carbon dioxide) corresponding to the solute (S502).

When the gas injection of the test tube 25 and the reference tube 26 is completed, the test tube input / output valve 28 and the reference tube input / output valve 29 are locked. At this time, the initial pressure of the test tube 25 and the reference tube 26 is the same.

Then, as time passes, solute (carbon dioxide) is dissolved in the solvent (PP) inserted into the test tube 25, and the pressure in the test tube 25 is reduced. On the other hand, since the pressure of the reference tube 26 is maintained in an initial state, a differential pressure is generated.

Therefore, the pressure difference between the test tube 25 and the reference tube 26 is measured at predetermined time intervals (S503). Then, the measured differential pressure is stored in the memory 42 of the measurement unit 40 or a separate external storage medium via the signal transmission line 22 (S504). At this time, the stored differential pressure is then used to calculate the amount of dissolution, and the amount of dissolution may be calculated and stored at the same time as the differential pressure measurement.

That is, here, the reduced pressure in the test tube 25 is the amount of gas dissolved in the specimen. Then, by multiplying the volume of the reference tube 26 by the density of the experimental conditions pressure, the weight of the gas (carbon dioxide) before dissolution can be calculated. In the same manner, the gas (carbon dioxide) weight in the test tube 25 can also be calculated. By calculating the difference between the weight of the test tube 5 and the weight of the reference tube 6, the amount of solute dissolved in the solvent can be obtained.

Thereafter, the present invention measures whether the measured differential pressure is the same as the previously measured differential pressure (S505), and if not the same, proceeds to the “S503” process and repeats the process. In addition, since the solubility according to a given condition is measured when the differential pressure measured in advance and the previously measured differential pressure are equal to each other, the gas discharge valve 30 is opened after the test tube input / output valve 28 and the reference tube input / output valve 29 are opened. By opening the gas of the test tube 25 and the reference tube 26 to stop the measurement (S506).

After the gas discharge is completed, the test tube input / output valve 28, the reference tube input / output valve 29, and the gas discharge valve 30 are well closed. Then, the amount of dissolution and the solubility over time are calculated using the differential pressure stored in the memory 42 or the external storage medium.

On the other hand, when the gas is discharged from the test tube 25 and the reference tube 26, pressure is generated in the test tube 25 while the dissolved gas is discharged from the solute by diffusion. In contrast, since the reference tube 26 maintains an atmospheric pressure state, a differential pressure is generated between the reference tube 26 and the test tube 25. At this time, by recording the generated differential pressure, it is possible to measure the diffusion of the gas by the same method as that of calculating the dissolved amount.

That is, after the gas discharge is completed, the test tube 25 and the reference tube 26 are kept in a sealed state, and the pressure difference between the test tube 25 and the reference tube 26 is measured at predetermined intervals. And a diffusivity is computed from the measured differential pressure.

Hereinafter, an embodiment according to the present invention will be described in more detail with reference to FIGS. 7A to 10B.

7A and 7B are graphs showing the results of measuring gas solubility using a gas solubility measuring apparatus according to an embodiment of the present invention. The measurement result is shown, and 7b has shown the carbon dioxide melt | dissolution amount measurement result in 14 g of HIPS pellets, 5.86 MPa, and 26 degreeC conditions.

8 is a table showing the amount of dissolution calculation of the gas solubility measuring apparatus according to an embodiment of the present invention, Figure 9 is a table showing the relationship between the gas pressure and density used in the amount of dissolution calculation.

For example, when the volume of the test tube 25 in FIG. 8 is 49.5 cm 3, the pressure in the reference tube 26 is 856 psi, and the pressure drop is 55 psi, the density of the test tube 25 and The density of the reference tube 26 is calculated, and the dissolved gas amount (0.99 g) and the dissolved amount (7.07 wt%) are calculated using the following equations (2) and (3).

Dissolved gas [g] = (density of reference tube-density of test tube) × (volume of test tube)

용해량[wt%] =

Dissolution amount [wt%] =

That is, the calculating device 41 of the measuring unit 40 calculates the dissolved gas amount and the dissolved amount by the above equations 2 and 3 based on the table of FIG. 9 and the differential pressure data recorded in the memory 42. do.

Referring to FIG. 8, the dissolved gas and dissolved amounts of the specimen PP shown in FIG. 7A are calculated as follows.

First, a density of 0.166 [g / cm 3] of the reference tube 26 is calculated from the initial pressure 856 psi of the reference tube 26 with reference to the table of FIG. 9.

The pressure 801 psi of the test tube 25 is calculated from the differential pressure 55 psi, and the density 0.146 [g / cm 3] of the test tube 25 is calculated based on this pressure.

The amount of dissolved gas is calculated using Equation (2). (I.e., (0.166-0.146) g / cm 3 × 49.5 cm 3 = 0.99 g)

= 7.07wt%]When the amount of dissolved gas is calculated, the amount of dissolved gas is calculated using Equation 3 above.

= 7.07wt%]

10A and 10B are graphs showing the results of measuring gas diffusivity using a gas solubility measuring apparatus according to an embodiment of the present invention. FIG. 10A is a diffusivity of PP in which 7 wt% carbon dioxide is dissolved in 9 hours. The measurement result is shown, and FIG. 10B shows the measurement result of the diffusivity of HIPS in which carbon dioxide was dissolved.

Looking at the diffusion of PP dissolved 7wt% carbon dioxide for 9 hours with reference to Figure 10a as follows.

That is, after 1 minute, 15% of the gas escaped, after 3 minutes, 29% of the gas escaped, and after 12 minutes, 50% of the gas escaped.

As described above, the present invention calculates the gas dissolution amount from the differential pressure between the test tube 25 and the reference tube 26 without taking out the specimen 25a, unlike the conventional method in which the specimen was directly taken out to measure the weight change amount. .

Therefore, although only one measurement of dissolution (solubility) was possible in a single gas injection / exhaustion, according to the present invention, stepwise dissolution and solubility are measured over time even with one gas injection / exhaust. I can do it. In particular, according to the present invention, the initial dissolution amount within 3 minutes, which could not be measured previously, can also be measured.

In addition, the conventional gas solubility measuring apparatus has a disadvantage in that the diffusion of the gas occurs while taking out the specimen, so that the exact gas diffusion cannot be measured. As shown in the above experimental results, the gas diffusion was initially very high, and it was found that about 30% of gas was diffused within 3 minutes. The gas solubility measuring apparatus according to the present invention is more accurate because it measures the degree of diffusion from the increase in pressure generated when gas is diffused from the specimen without the process of taking out the specimen.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

As described above, the present invention calculates the amount of dissolution from the differential pressure of the gas injected without taking out the specimen, and thus has the effect of measuring the amount of solubility and the solubility in phases over time by one gas injection / exhaust.

In addition, since the present invention measures the degree of diffusion from the increase in pressure generated while gas is diffused from the sample without taking out the specimen, there is an effect that can more accurately measure the degree of diffusion of the gas.

Claims (11)

A tubing tube having an empty interior, a test tube inserted with a specimen corresponding to a solvent in which gas is to be dissolved and maintaining a sealing state after gas injection; A reference tube that maintains a sealing state after gas injection as a tubing tube having the same material and volume as the test tube; A differential pressure gauge for measuring a differential pressure between the test tube and the reference tube at a predetermined interval after gas injection; And a means for calculating a gas solubility of the specimen based on the differential pressure data received from the differential pressure gauge. The method of claim 1, wherein the calculating means And a memory for recording the differential pressure data. The method of claim 2, A connection pipe for connecting an external gas supply device, the test tube, the reference tube, and the differential pressure gauge to each other; And Gas solubility measuring device further comprises a connection valve for controlling the injection and discharge of the gas supplied from the outside through the connection pipe and to maintain the sealing state of the test tube and the reference tube. The method according to claim 3, wherein the test tube and the reference tube, Gas solubility measurement device characterized in that the gas is injected from the outside through the connecting pipe and the connecting valve, the same initial pressure at the time of gas injection. The method of claim 4, wherein The differential pressure gauge, After the gas solubility measurement is completed and the gas of the test tube and the reference tube is discharged, further performing a function of measuring the differential pressure generated by the diffusion of the gas dissolved in the test tube specimen, And said calculating means further calculates gas diffusivity using said differential pressure. The method of claim 5, And a signal transmission line for transmitting the differential pressure data measured by the differential pressure gauge to the calculation means. The method of claim 5, wherein the connection valve, A gas injection valve capable of controlling the gas to be used for measurement to be injected; A gas discharge valve capable of controlling the injected gas to be discharged; A differential pressure valve capable of controlling a flow path between the test tube and the reference tube; A differential pressure gauge needle valve capable of opening and closing a flow path between the test tube and the reference tube and the differential pressure gauge; A test tube input / output valve capable of controlling the gas injected through the gas injection valve into and out of the test tube; And Gas solubility measuring device comprising a reference tube input and output valve that can control the gas injected through the gas injection valve to enter and exit the reference tube. The method of claim 7, wherein the connector, A tubing tube connecting the gas introduced from the gas injection valve to the test tube input / output valve, the reference tube input / output valve, and the gas discharge valve; And And a tubing union for connecting the test tube and the reference tube with the differential pressure gauge. A gas injection step of maintaining a sealing state after injecting a gas to be measured at the same pressure into a test tube containing a specimen and a reference tube having the same volume and material as that of the test tube; A differential pressure measuring step of measuring a differential pressure between the test tube and the reference tube at predetermined intervals; And a solubility calculation step of calculating solubility from the measured differential pressure. The method of claim 9, A gas discharge step of discharging the gas as the solubility calculation is completed; After the gas discharge is completed, maintaining the test tube and the reference tube in a sealed state; Measuring a differential pressure between the test tube and the reference tube at predetermined intervals; And The gas solubility measuring method further comprises the step of calculating the diffusivity from the measured differential pressure. The method of claim 10, wherein the solubility calculation step, Checking whether the measured differential pressure is the same as the previously measured differential pressure, and if the same is the same, proceeds to the gas discharge step; otherwise, returns to the differential pressure measuring step.

Images