JPH0650956A - All organic body carbon measuring device - Google Patents

Abstract

PURPOSE:To increase measurement accuracy by increasing carbon dioxide concentration which is extracted by a wet oxidation method. CONSTITUTION:A sparging gas is supplied to the lower part of an oxidation reaction container 2 from a sparging gas supply channel with a throttle 16 which becomes a channel resistance. A vapor part is located at the upper part of the oxidation reaction container 2 and a delivery gas channel 20 with a vacuum pump 22 is connected to the vapor part. The pressure of the vapor at the oxidation reaction container 2 is reduced and dissolved carbon dioxide is extracted by the sparge gas and then is detected by a non-dispersion type infrared ray analyzer 26 after the pressure is returned to a normal one.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a total organic carbon measuring device for measuring a small amount of organic carbon in sample water, for example, ultrapure water.

[0002]

2. Description of the Related Art An apparatus for measuring total organic carbon converts total organic carbon in sample water contained in an oxidation reaction container into carbon dioxide in a liquid phase by an oxidizing reagent or ultraviolet irradiation, and then spargs into the sample water after conversion. The gas is blown in to extract carbon dioxide, which is then introduced into a carbon dioxide gas detector such as a non-dispersive infrared analyzer to measure total organic carbon. Conventionally, carbon dioxide that has been oxidized and dissolved in sample water is extracted by sparging under normal pressure.

[0003]

In order to completely extract carbon dioxide dissolved in sample water by sparging,
A large amount of sparging gas is required for the amount of dissolved carbon dioxide. Therefore, the extracted carbon dioxide is diluted with a large amount of sparging gas, and when it is detected by a carbon dioxide gas detector, the carbon dioxide concentration is low, and the height of the obtained detection peak is low, which makes it wide. Therefore, there is a disadvantage in the lower limit of quantification. An object of the present invention is to increase the concentration of carbon dioxide extracted from sample water with a sparging gas and to make the obtained carbon dioxide peak steep to improve the measurement accuracy in a total organic carbon measuring device.

[0004]

According to the present invention, a flow path resistance is provided in a sparging gas supply flow path for supplying a sparging gas into a sample water in an oxidation reaction container for converting all organic carbon in the sample water into carbon dioxide. An exhaust means is provided in the exhaust gas flow path for extracting carbon dioxide in the sample water with a sparging gas and discharging the carbon dioxide in the sample water with the sparging gas by providing a gas phase portion in the oxidation reaction vessel with a decompressed state. .

[0005]

[Function] After all the organic carbon in the sample water is oxidized and converted into carbon dioxide in the oxidation reaction container, the sparging gas is supplied from the sparging gas supply passage and the exhaust means of the exhaust gas passage is operated. When the carbon dioxide is extracted by the sparging gas, the gas phase in the oxidation reaction container is depressurized by the flow path resistance of the sparging gas supply flow path and the exhaust means of the exhaust gas flow path for extraction.
When the gas phase is depressurized, the transfer of dissolved carbon dioxide to the gas phase is promoted for the following reasons. One reason is that the decompression state of the gas phase shifts the distribution equilibrium of the dissolved carbon dioxide between the gas phase and the liquid phase, which promotes the transfer of the dissolved carbon dioxide to the gas phase. . Another reason is that when performing sparging, the larger the gas-liquid contact area between the sparging gas and the sample water, the easier the dissolved carbon dioxide is transferred to the sparging gas. This is because the gas-liquid contact area increases because the volume increases. Therefore, if the amount of sparging gas is the same, the extraction efficiency of dissolved carbon dioxide will be better under reduced pressure than under normal pressure.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment. Reference numeral 2 denotes an oxidation reaction container, into which sample water and an oxidizing reagent are introduced by a mechanism 4 for introducing and discharging sample water or the like provided at the bottom. Reference numeral 3 is a sample water or the like introduced into the oxidation reaction container 2, and the sample water contains an oxidizing reagent. As the oxidizing reagent, sulfuric acid, potassium peroxodisulfate and the like are used. The organic carbon in the sample water may be oxidized by UV irradiation instead of the oxidizing reagent. At that time, the oxidizing reagent may or may not be added to the sample water 3 or the like. The sample water 3 after the measurement is discharged from the introduction / discharge mechanism 4.

A sparging gas supply channel 6 for supplying a sparging gas is provided below the oxidation reaction container 2. The sparging gas supply flow path 6 includes a gas source 8 of a sparging gas that does not contain carbon components such as high-purity air and nitrogen, a flow rate controller 10, a flow meter 12, a three-way solenoid valve 14 for switching the flow path, and a flow path resistance. A diaphragm 16 and a bubbler 18 for discharging sparging gas are provided below the oxidation reaction container 2. There is a vapor phase portion in the upper part of the oxidation reaction container 2, and the exhaust gas flow path 20 is connected to the vapor phase portion. A vacuum pump 22 is provided in the exhaust gas passage 20. The vacuum pump 22 does not emit a carbon component, and an example thereof is a two-stage diaphragm type vacuum pump. An electronic cooler 24 for removing water from the sparged gas containing the extracted carbon dioxide is provided downstream of the vacuum pump 22, and a non-dispersive infrared analyzer 26, which is a carbon dioxide gas detector, is provided downstream of the electronic cooler 24. Is provided. The other contact (NO) of the three-way solenoid valve 14 provided in the sparging gas supply channel 6 is a vacuum pump 22.
And the electronic cooler 24 are connected to the flow path.

Next, the operation of the embodiment shown in FIG. 1 will be described. When performing an operation of introducing the sample water 3 or the like into the oxidation reaction vessel 2, performing an operation of discharging the sample water 3 or the like in the oxidation reaction vessel 2, or when performing an oxidation reaction in the oxidation reaction vessel 2. Sets the three-way solenoid valve 14 to one for connecting COM and NO to set the sparging gas to the oxidation reaction container 2
Flow through the analyzer 26 without passing. After the oxidation reaction is completed, the three-way solenoid valve 14 is switched to the one connecting COM and NC, and the sparging gas is introduced into the sample water 3 or the like from the bubbler 18 through the throttle 16, and the vacuum pump 22
Operate. Restrictor 16 of sparging gas supply channel 6
The amount of sparging gas flowing into the oxidation reaction container 2 is limited by the above, and the vacuum pump 2 is supplied from above the oxidation reaction container 2.
Since the gas is exhausted at 2, the pressure of the gas phase in the oxidation reaction container 2 drops below atmospheric pressure, and sparging is performed under reduced pressure. The sparging gas containing carbon dioxide that has passed through the vacuum pump 22 returns to normal pressure, passes through the electronic cooler 24, and then the analyzer 2
6, and the carbon dioxide concentration is measured.

FIG. 2 shows an example of the measurement result. 250 μl of sample water having a carbon concentration of 400 ppb was introduced into the oxidation reaction container 2 for measurement. High-purity air was used as the sparging gas, and the flow rate was 150 ml / min. (A) is a case where the dissolved carbon dioxide is extracted by sparging under normal pressure without operating the vacuum pump 22 as in the conventional case. On the other hand, (B) is a case where the vacuum pump 22 is operated, the gas phase pressure in the oxidation reaction container 2 is reduced to about 1/2 atm, and the sparging is performed to extract the dissolved carbon dioxide. (A) and (B) are vertical axes,
The horizontal axis shows the same scale. Comparing the conventional case (FIG. 2 (A)) and the case of this embodiment (FIG. 2 (B)), the peak areas of both are almost equal, but the peak height is approximately doubled by reducing the pressure. You can see that it is.

FIG. 3 shows a second embodiment. The electronic cooler 24 and the analyzer 26 in the embodiment of FIG.
A pressurizing pump 28 is provided between them, and a passage resistance throttle 30 is provided at the outlet of the analyzer 26. Thereby, the extracted carbon dioxide is compressed and detected by the analyzer 26. When detecting carbon dioxide with the analyzer 26,
The wider the target carbon dioxide is dispersed in the flow direction of the sparging gas flow path, the more gently the output peak of the detector becomes, which is disadvantageous for trace measurement. On the other hand, as in the embodiment of FIG. 1, carbon dioxide is extracted by performing sparging under reduced pressure, and when the extracted carbon dioxide is detected, the peak of the output signal is made sharp by returning to normal pressure. Further, as in the embodiment of FIG. 3, by actively compressing the sparging gas containing the extracted carbon dioxide to further reduce the dispersion of carbon dioxide in the flow direction of the sparging gas, the peak of the output signal can be obtained. The height can be further increased.

[0011]

EFFECTS OF THE INVENTION Since sparging for extracting dissolved carbon dioxide in an oxidation reaction vessel is carried out under reduced pressure, and the extracted carbon dioxide is detected under normal pressure or under increased pressure, it is converted into the normal pressure sparging gas flow rate. At this time, the dissolved carbon dioxide can be efficiently extracted with a small amount of sparging gas, and therefore, the carbon dioxide concentration in the sparging gas can be concentrated when the pressure is returned to normal pressure. As a result, highly sensitive carbon dioxide detection can be performed without changing the specifications of the carbon dioxide detector.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example.

2A and 2B are diagrams comparing measurement results of a conventional example and this example, FIG. 2A is an example of conventional sparging under normal pressure, and FIG. 2B is an example of sparging under reduced pressure according to one example. Is.

FIG. 3 is a flow chart showing an exhaust gas flow passage and a carbon dioxide gas detector portion in another embodiment.

[Explanation of symbols]

 2 Oxidation reaction vessel 3 Sample water, etc. 4 Introduction mechanism of sample water, etc. Discharge mechanism 6 Sparging gas supply flow path 14 Three-way solenoid valve 16, 30 Throttle 20 Exhaust gas flow path 22 Vacuum pump 26 Non-dispersive infrared analyzer 28 Pressurization pump

Claims (1)

[Claims] 1. An oxidation reaction vessel for converting all organic carbon in sample water into carbon dioxide, and a sparging gas for supplying a sparging gas containing no carbon component to the sample water in the oxidation reaction vessel via a flow path resistance. A supply flow path, an exhaust gas flow path which is provided with an exhaust means and which makes the gas phase portion in the oxidation reaction vessel a decompressed state to extract carbon dioxide in the sample water by a sparging gas and discharges it, and is guided by the exhaust gas flow path. And a carbon dioxide gas detector for detecting carbon dioxide.