JP5861890B2 - Method for measuring the amount of dissolved gas in a pressurized liquid - Google Patents

Description

  The present invention relates to a method for measuring the amount of gas dissolved in a pressurized liquid.

  Conventionally, as a method of measuring the amount of gas dissolved in a liquid such as water, the dissolved gas is extracted into the gas phase by evacuating the liquid or by evacuating the liquid while vibrating with ultrasonic waves. Known are a vacuum extraction method (decompression method), a hot water bath method in which a liquid is subjected to hot water bath, and dissolved gas is separated and extracted by heating (for example, see Patent Document 1).

JP 2006-71340 A

  However, the conventional vacuum extraction method has an advantage that the amount of dissolved gas can be measured in a relatively short time, but it is difficult to completely extract the dissolved gas from the liquid even if ultrasonic waves are used. In addition, since the liquid is opened to the atmosphere at the time of measurement, the amount of dissolved gas changes due to contact with the atmosphere. For this reason, in the vacuum extraction method, in particular, it is difficult to accurately measure the amount of dissolved gas in the pressurized liquid pressurized at high pressure and the pressurized liquid pressurized at high pressure. was there.

  On the other hand, in the hot water method, the amount of dissolved gas can be measured in a relatively short time, but the dissolved gas remains in the liquid even if the hot water temperature is 100 ° C. For this reason, it is still difficult to accurately measure the amount of dissolved gas in the pressurized liquid pressurized at a high pressure or the pressurized liquid pressurized at a high pressure.

  In view of the circumstances described above, an object of the present invention is to provide a method for measuring the amount of dissolved gas in a pressurized liquid that enables accurate and efficient measurement of the amount of dissolved gas in the pressurized liquid. .

  In order to achieve the above object, the present invention provides the following means.

  The method for measuring the amount of dissolved gas in the pressurized liquid according to the present invention is a method for measuring the amount of gas dissolved in the pressurized liquid, wherein the pressurized liquid is allowed to flow into the sampling vessel while generating cavitation. And collecting the supersaturated dissolved gas dissociated from the pressurized liquid by the cavitation and measuring the amount of the supersaturated dissolved gas in the supersaturated dissolved gas amount measuring step and the supersaturated dissolved gas amount measuring step in the sampling container. Using the collected pressurized liquid, carbon dioxide is generated in the pressurized liquid, dissolved gas in the pressurized liquid is entrained by the bubbles of carbon dioxide and carbon dioxide is removed, and dissolved substances other than carbon dioxide are dissolved. The step of measuring the amount of gas other than carbon dioxide, and the pressurized liquid collected in the sampling vessel in the step of measuring the amount of supersaturated dissolved gas Using a dissolved carbon dioxide content measuring step for obtaining a total acidity of the pressurized liquid and obtaining an amount of dissolved carbon dioxide in the pressurized liquid from the total acidity, wherein the amount of the supersaturated dissolved gas and other than the carbon dioxide The amount of dissolved gas and the amount of dissolved carbon dioxide are added together to determine the amount of dissolved gas in the pressurized liquid.

  Here, the “pressurized liquid” in the present invention includes not only a liquid in a pressurized state but also a pressurized liquid.

In the method for measuring the amount of dissolved gas in the pressurized liquid of the present invention, in the supersaturated dissolved gas amount measuring step, the pressurized liquid is sampled in the sampling vessel while generating cavitation, so that the supersaturated from the pressurized liquid is obtained. Dissolved gas can be dissociated and collected efficiently and effectively, and the amount of supersaturated dissolved gas can be measured.
Also, in the step of measuring the amount of dissolved gas other than carbon dioxide, the amount of dissolved gas other than carbon dioxide is generated by generating carbon dioxide in the pressurized liquid and entraining the dissolved gas in the pressurized liquid with bubbles of carbon dioxide. Can be measured.
Further, in the dissolved carbon dioxide amount measurement step, the total acidity of the pressurized liquid can be obtained, and the amount of dissolved carbon dioxide in the pressurized liquid can be obtained from the total acidity.

  Therefore, in the method for measuring the amount of dissolved gas in the pressurized liquid of the present invention, a supersaturated dissolved gas amount measuring step, a dissolved gas amount measuring step other than carbon dioxide, and a dissolved carbon dioxide amount measuring step (water replacement method, Combining the three types of processes of the carbon dioxide expelling method and the acidity method) makes it possible to reliably measure the amount of dissolved gas in the pressurized liquid, which has conventionally been difficult to measure.

It is a figure which shows the discharge path | route which discharges | emits high pressure wastewater from the bottom water drainage tank which an LPG storage tank comprises, and the sampling apparatus provided in this discharge path. It is a figure which shows a sampling apparatus, and is a figure which shows the state which is performing the supersaturated dissolved gas amount measurement process of the measuring method of the dissolved gas amount in the to-be-pressurized liquid which concerns on this invention. It is a figure which shows the dissolved gas amount measurement process other than the carbon dioxide of the measuring method of the dissolved gas amount in the to-be-pressurized liquid which concerns on this invention.

  Hereinafter, with reference to FIGS. 1 to 3, a method for measuring the amount of dissolved gas in a pressurized liquid according to an embodiment of the present invention will be described. Here, in this embodiment, although it demonstrates as what measures the quantity of the gas dissolved in the high pressure waste_water | drain in the bottom water drainage tank which an LPG storage tank comprises, the dissolved gas in the to-be-pressurized liquid concerning this invention Of course, the method of measuring the amount is also applicable to measuring the amount of dissolved gas in a liquid other than pressurized or pressurized water.

  First, as shown in FIG. 1 and FIG. 2, by using the method for measuring the amount of dissolved gas in the pressurized liquid according to the present embodiment, high-pressure drainage (high-pressure water, When measuring the amount of dissolved gas in the pressurized liquid W, a sampling device 4 is installed in the discharge path 3 for discharging the high-pressure waste water W from the bottom water drain tank 2.

  Here, the discharge path 3 includes a pump 5 disposed in the high-pressure drain W of the bottom water drain tank 2 and a drain pipe 6 extending from the pump 5 to the outside of the LPG storage tank 1. Further, the drain pipe 6 includes, in order from the pump 5 side, a check valve 7 with a balance hole, a first automatic control valve 8, a second automatic control valve 9, a flow rate transmitter 10, a flow rate adjustment valve 11, an orifice 12, and the like. Is provided. Furthermore, the 1st branch piping 15 is connected between the 1st automatic control valve 8 and the 2nd automatic control valve 9, and this 3rd automatic control valve 16, in order from this branch connection part side to this 1st branch piping 15, An exhaust valve 17, a first on-off valve 19, a volume tank 20, and the like are provided. Further, a second branch pipe 21 and a third branch pipe 22 are provided between the flow transmitter 10 and the flow control valve 11 and between the flow control valve 11 and the orifice 12, respectively. Each of the third branch pipes 22 is provided with an on-off valve (second on-off valve 23, third on-off valve 24).

  The sampling device 4 of the present embodiment includes a connecting pipe 25 connected to the on-off valves 23 and 24 of the second branch pipe 21 and the third branch pipe 22, and a connecting pipe 25 from the second branch pipe 21 side. A constant flow valve 26, a fourth on-off valve 27, a fifth on-off valve 28, and a fourth branch pipe 29, a fifth branch branchingly connected between the fourth on-off valve 27 and the fifth on-off valve 28. A pipe 30 is provided. In addition, a sixth on-off valve 31 is detachably provided on the fourth branch pipe 29, and a seventh on-off valve 32 is detachably provided on the fifth branch pipe 30. , 34 are connected. At this time, sampling containers 33 and 34 are connected via a needle valve 35 for flow rate adjustment. Each sampling container 33 and 34 has a pressure resistance of 12.4 MPa with a capacity of 300 cc, for example.

  And in the measuring method of the dissolved gas amount in the pressurized liquid of the present embodiment, the supersaturated dissolved gas amount measuring step, the dissolved gas amount measuring step other than carbon dioxide, the dissolved carbon dioxide amount measuring step (the water displacement method, Three types of processes, carbon dioxide expulsion method and acidity method, are carried out to measure the amount of dissolved gas in high-pressure wastewater (pressured liquid).

  First, a supersaturated dissolved gas amount measurement step (water replacement method) is performed. As shown in FIG. 2, this supersaturated dissolved gas amount measurement step is performed at the same time as the drainage (pressured liquid) W is collected in the sampling container 34 by the sampling device 4. Specifically, in the supersaturated dissolved gas amount measurement step, the flow rate adjustment valve 11 is closed and the on-off valves 23, 24, 27, 28, 29, and 32 are opened, and the waste water W is introduced into the sampling containers 33 and 34 and collected. . At this time, by operating the needle valve 35, the flow rate of the waste water W flowing into the sampling vessel 34 is reduced to, for example, about 0.5 L / min, and the waste water W is sampled while generating cavitation by adjusting to this predetermined flow rate. Collect in container 34.

  And by generating cavitation in this way, the supersaturated dissolved gas R1 in the waste water W is entrained and dissociated. This supersaturated dissolved gas R1 is collected from a sampling vessel 34 through a pipe 36 by a graduated cylinder 37 on the water, and its volume is measured. Thereby, the amount of supersaturated dissolved gas R1 is measured in-situ by the supersaturated dissolved gas amount measurement process among all the dissolved gases dissolved in the high pressure waste water W.

  Next, a process for measuring the amount of dissolved gas other than carbon dioxide (purge method using carbon dioxide) is performed. In the dissolved gas amount measuring step other than carbon dioxide, the waste water W collected in the sampling containers 33 and 34 in the supersaturated dissolved gas amount measuring step is used to generate carbon dioxide in the waste water W. And the dissolved gas in the waste_water | drain W is entrained by the bubble of a carbon dioxide, and the amount of dissolved gas other than a carbon dioxide is measured by removing a carbon dioxide.

  Specifically, in the dissolved gas amount measurement step other than carbon dioxide, the dissolved gas amount is measured in the analysis chamber with respect to the waste water (sample water, pressurized liquid) W collected by the sampling container 34. As shown in FIG. 3A, first, 5 g of marble 41 is placed in a 250 ml sample bottle 40, and 250 ml of the waste water W in the sampling container 34 is injected into the sample bottle 40 using a water collection tube.

  Next, as shown in FIG. 3B, an HCl burette 44 having an HCl stopper 43 at the bottom is assembled and connected to the sample bottle 40, and 15 ml of HCl (2 + 1) S1 is attached to the burette 44 from above. Then, a NaOH stopper 45 is attached to the upper part of the burette 44, and HCl (2 + 1) S1 is enclosed.

  Further, as shown in FIG. 3C, an NaOH burette 46 is assembled on the HCl burette 44, and a 20% NaOH solution S2 is injected into the NaOH burette 46 to fill it. At this time, 50 g / l Rochelle salt is added to the NaOH solution S2 in order to prevent precipitation of calcium hydroxide.

Then, as shown in FIG. 3D, when the HCl stopper 43 is opened and HCl (S1) is lowered to the sample bottle 40, HCl (S1) and the marble 41 react to react with carbon dioxide (CO ₂ ). Will occur. When carbon dioxide is generated in this way, dissolved gas is entrained by carbon dioxide bubbles. Further, when the dissolved gas and carbon dioxide that are entrained are passed through the NaOH solution S2, the carbon dioxide is absorbed by the NaOH solution S2, and only the dissolved gas R2 other than carbon dioxide is collected. Therefore, the amount of dissolved gas R2 other than carbon dioxide is measured by measuring the collected dissolved gas R2.

Next, since the dissolved gas amount other than carbon dioxide was measured in the dissolved gas amount measuring step other than carbon dioxide, the remaining gas amount of carbon dioxide (CO ₂ ) was measured by the dissolved carbon dioxide amount measuring step (acidity method). To do. In this dissolved carbon dioxide amount measuring step, the wastewater W collected in the sampling vessels 33 and 34 in the supersaturated dissolved gas amount measuring step is used, a phenolphthalein test solution is added to the wastewater W, and the NaOH solution is titrated to pH 8.3. The total acidity is calculated from the titration amount using as a quantification point. Then, the mass of free carbonic acid (carbon dioxide dissolved in water) is determined from the total acidity, and the amount of dissolved carbon dioxide R3 in the waste water is determined by converting the mass into volume.

  Specifically, in the dissolved carbon dioxide amount measuring step, the amount of dissolved carbon dioxide is measured in the analysis chamber with respect to the waste water (sample water, pressurized liquid) W collected by the sampling containers 33 and 34.

Here, the acidity is the alkali content required to neutralize the acid content of carbonic acid, mineral acid, organic acid, etc. contained in water, expressed in ppm of the corresponding CaCO ₃ , 1 ppm (mg / l) is defined as 1 degree. The total acidity is the total acid content in water expressed in ppm of the corresponding CaCO ₃ .

In this embodiment, first, the total acidity of the waste water W collected in the sampling containers 33 and 34 is quantified using a phenolphthalein measurement method. When quantifying the total acidity of wastewater W by this phenolphthalein measurement method, take 100 ml of wastewater (sample water W) in a colorimetric tube, add 4 to 5 drops of phenolphthalein reagent (indicator), and place it on a white paper. Titrate with a NaOH solution of 0.02 N (0.02 mol / l; 1 ml of this solution corresponds to 1 mg of CaCO ₃ ) until a slight iridescent color remains, and perform a preliminary test. Next, 100 ml of waste water (sample water W) is taken in another colorimetric tube, 4 to 5 drops of phenolphthalein reagent are added, and 0.02 normal NaOH solution of the same amount as consumed in the preliminary test is added thereto. In addition, if the rainbow color disappears slightly after shaking, continue the same rule. When the rainbow color remains without disappearing, the free carbonic acid is not dissolved, so the equivalent point (end point) of NaHCO ₃ at pH 8.3 is defined as the total acidity.

The chemical reaction formula at the time of titration is CO ₂ + NaOH → NaHCO ₃ . Finally, from the total ml number a of the 0.02 normal NaOH solution at the time when the rainbow color remained without disappearing, the total acidity by [total acidity (CaCO ₃ ppm) = a × 1000 / ml sample water] Is calculated.

Then, the amount of free carbonic acid (carbon dioxide dissolved in the wastewater) R3 is determined in terms of the total acidity.
At this time, the mass calculation formula of free carbonic acid is free carbonic acid (CO ₂ ppm; mg / l) = [total acidity (CaCO ₃ ppm) −mineral acidity (CaCO ₃ ppm)] × 0.88. The volume calculation formula is as follows: free carbonic acid (CO ₂ ml / l) = CO ₂ ppm / 44.01 × 22.263.

In addition, the [mineral acidity] in the mass calculation formula of free carbonic acid is a general term for mineral acids (acids including non-metals other than carbonic acid) such as H ₂ SO ₄ , HCl, and HNO _3. Acidity. Further, when ferric salt and aluminum salt are contained in the sample water (drainage W) in a significant amount, iron and aluminum are measured, and the corresponding ppm (mg / l) of CaCO ₃ is measured. The remainder after subtraction is defined as the mineral acidity. The equivalence point is pH 4.8, and titration is performed with a 0.02 N NaOH solution. Therefore, if the sample water has a pH of 4.8 or more, there is no mineral acidity.

Moreover, (0.88) in the mass calculation formula of free carbonic acid is a conversion ratio when calculating the calculation formula of total acidity by converting it into CO _{2 of the} same normality. Furthermore, (44.01) in the volume calculation formula of free carbonic acid is based on the molecular weight of the Chemical Society of Japan Atomic Weight Committee “4-digit atomic weight table (2010)”. Moreover, (22.263) in the volume calculation formula of free carbonic acid is based on the physical property value (volume) of 1 mol of CO _{2 in} the actual gas.

  And, as described above, 3 of the supersaturated dissolved gas amount measuring step, the dissolved gas amount measuring step other than carbon dioxide, and the dissolved carbon dioxide amount measuring step (water displacement method, carbon dioxide expelling method, and acidity method) By adding up the amount of the supersaturated dissolved gas R1 measured in the types of processes, the amount of the dissolved gas R2 other than carbon dioxide, and the amount of the dissolved carbon dioxide R3, the amount of dissolved gas in the high-pressure waste water can be obtained.

  Therefore, in the method for measuring the dissolved gas amount in the pressurized liquid according to the present embodiment, the pressurized liquid (high pressure waste water) W is collected in the sampling containers 33 and 34 while generating cavitation in the supersaturated dissolved gas amount measuring step. By doing so, the supersaturated dissolved gas R1 can be efficiently and effectively dissociated and collected from the pressurized liquid W, and the amount of the supersaturated dissolved gas R1 can be measured.

  Further, in the step of measuring the amount of dissolved gas other than carbon dioxide, carbon dioxide is generated in the pressurized liquid W, and the dissolved gas in the pressurized liquid W is entrained by the bubbles of carbon dioxide, thereby dissolving other than carbon dioxide. The amount of gas R2 can be measured.

  Further, in the dissolved carbon dioxide amount measuring step, the total acidity of the pressurized liquid W can be obtained, and the amount of dissolved carbon dioxide R3 in the pressurized liquid W can be obtained from the total acidity.

  Therefore, in the method for measuring the amount of dissolved gas in the pressurized liquid of the present embodiment, three types of processes, a supersaturated dissolved gas amount measuring step, a dissolved gas amount measuring step other than carbon dioxide, and a dissolved carbon dioxide amount measuring step. By combining the above, it becomes possible to reliably measure the amount of dissolved gas in the pressurized liquid, which has been difficult to measure conventionally.

  As mentioned above, although one Embodiment of the measuring method of the dissolved gas amount in the pressurized liquid which concerns on this invention was described, this invention is not limited to said embodiment, It changes suitably in the range which does not deviate from the meaning. Is possible.

DESCRIPTION OF SYMBOLS 1 LPG storage tank 2 Bottom water drainage tank 3 Discharge path 4 Sampling device 5 Pump 6 Drain pipe 7 Check valve 8 with balance hole 1st automatic control valve 9 2nd automatic control valve 10 Flow transmitter 11 Flow control valve 12 Orifice 15 First branch pipe 16 Third automatic control valve 17 Exhaust valve 19 First on-off valve 20 Volume tank 21 Second branch pipe 22 Third branch pipe 23 Second on-off valve 24 Third on-off valve 25 Connection pipe 26 Constant flow valve 27 First 4 on-off valve 28 5th on-off valve 29 4th branch pipe 30 5th branch pipe 31 6th on-off valve 32 7th on-off valve 33 sampling container 34 sampling container 35 needle valve 36 pipe 37 graduated cylinder 40 sample bottle 41 marble 42 sampling pipe 43 HCl plug 44 HCl burette 45 NaOH plug 46 NaOH burette R1 Supersaturated dissolved gas R2 Carbon dioxide Outside dissolved gas R3 Dissolved carbon dioxide S1 Hydrochloric acid solution S2 Sodium hydroxide solution W Drainage (sample water, pressurized liquid)

Claims (1)

A method for measuring the amount of gas dissolved in a pressurized liquid,
The supersaturated dissolved gas that collects the supersaturated dissolved gas dissociated from the pressurized liquid by the cavitation and collects the supersaturated dissolved gas and collects the pressurized liquid while flowing into the sampling vessel while generating cavitation. A quantity measuring step;
Using the pressurized liquid collected in the sampling vessel in the supersaturated dissolved gas amount measuring step, generating carbon dioxide in the pressurized liquid, and entraining the dissolved gas in the pressurized liquid with carbon dioxide bubbles Removing the carbon dioxide and measuring the amount of dissolved gas other than carbon dioxide;
Using the pressurized liquid collected in the sampling vessel in the supersaturated dissolved gas amount measurement step, the total acidity of the pressurized liquid is obtained, and the dissolved carbon dioxide for obtaining the amount of dissolved carbon dioxide in the pressurized liquid from the total acidity A quantity measuring step,
In the pressurized liquid, the amount of the dissolved gas in the pressurized liquid is obtained by adding up the amount of the supersaturated dissolved gas, the amount of dissolved gas other than the carbon dioxide, and the amount of the dissolved carbon dioxide. Of measuring the amount of dissolved gas.

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