JPH0827273B2 - Carbon measuring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon measuring device for measuring total organic carbon (TOC) in an aqueous solution sample and carbon content in a solid sample.

[0002]

2. Description of the Related Art A carbon measuring device is equipped with a carrier gas supply section, a sample injection section, a combustion oxidation reaction section and a CO ₂ detection section in order to measure both an aqueous solution sample and a solid sample. In the organic carbon measuring device for measuring the total organic carbon, the solid sample introducing section for guiding the carbon content in the solid sample in the solid sample combustion oxidation reaction section as carbon dioxide to the CO ₂ detecting section together with the carrier gas, There is a carbon measuring device that measures gas in both flow paths of an aqueous solution sample and a solid sample with one common CO ₂ detector. As the CO ₂ detection unit, for example, a non-dispersive infrared gas analyzer (ND
IR) is used. As the NDIR measurement cell, the same measurement cell is commonly used for both the aqueous solution sample flow path and the solid sample flow path.

[0003]

In the case of an aqueous solution sample, the measurement of TOC of several ppm to several hundred ppm is usually the main component, and the amount of sample used for the measurement is several tens μl (several tens mg). The aqueous solution sample is injected into the high temperature combustion oxidation reaction tube, but at that time, it is difficult to inject a large amount of the aqueous solution sample into the combustion oxidation reaction tube because the water content is rapidly vaporized and the volume is expanded. On the other hand, the carbon concentration of the solid sample is as high as several thousand ppm to several percent, and the amount of the sample is several tens to several hundreds mg in order to facilitate weighing by a balance and prevent uneven distribution of carbon in the solid sample as much as possible. It is desirable to do. Therefore, the amount of CO ₂ generated is about 100 times as large in the solid sample as in the case of the aqueous solution sample.

Since the conventional carbon measuring apparatus mainly focuses on the measurement of the aqueous solution sample, the NDIR measuring cell is set for the aqueous solution sample. Therefore, if the measuring cell is used for measuring a solid sample, only a very low concentration of carbon content can be measured, or a very small amount of solid sample must be weighed. A first object of the present invention is to provide a carbon measuring device capable of performing measurement under appropriate conditions in both measurement of an aqueous solution sample and measurement of a solid sample. A second object of the present invention is to provide a carbon measuring device capable of measuring by switching the sensitivity when the carbon concentration in the sample changes or the sample amount changes.

[0005]

According to the present invention, an organic carbon measuring apparatus equipped with a carrier gas supply section, a sample injection section, a combustion oxidation reaction section and a CO ₂ detection section for measuring total organic carbon in an aqueous solution sample. And a solid sample introduction part for guiding carbon content in the solid sample as carbon dioxide in the solid sample combustion oxidation reaction part together with a carrier gas to the CO ₂ detection part.
A non-dispersive infrared gas analyzer in which two measurement cells having different optical path lengths of the measurement light flux are arranged in series with respect to the measurement light flux is used for the O ₂ detection unit, and the gas in the aqueous solution sample measurement flow path has a long optical path length. The gas in the measurement channel was introduced into the measurement cell, and the gas in the measurement channel of the solid sample was introduced into the measurement cell having a short optical path length. In order to switch the sensitivities, switching can be performed by switching the gas in the flow channel being measured between the aqueous solution sample measurement channel and the solid sample measurement channel and the CO ₂ detection unit to either of two measurement cells. Means are provided.

[0006]

The sensitivity is high in the measuring cell having the long optical path length of the measuring light beam, and is low in the measuring cell having the short optical path length of the measuring light beam. Generally, CO ₂ generated from an aqueous solution sample
Since the amount of gas is small and the amount of CO ₂ gas generated by the solid sample is large, the gas from the aqueous solution sample is guided to a measuring cell with a long optical path length and measured, and the gas from the solid sample is measured into a measuring cell with a short cell length. Guide and measure. When the switching means is provided, for example, in the case of measuring a solid sample, when the carbon component concentration of the solid sample is extremely low, the switching means switches the gas flow path from the solid sample to the high-sensitivity measurement. To the measurement cell side with a long optical path length.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment. A sample injector 2 and a switching valve 4 are provided to form a sample injection unit for the aqueous solution sample. A fixed amount of the aqueous solution sample 6 is sampled by the sample injector 2 and the combustion oxidation reaction unit is switched by the switching valve 4. 8 or IC (inorganic carbon) reactor 10. The combustion oxidation reaction section 8 is provided with a TC (all carbon) combustion tube 12 filled with an oxidation catalyst 13, and a heating furnace 14 is provided outside the combustion tube 12 to heat the combustion tube 12. A required amount of the aqueous solution sample is injected into the combustion tube 12 by the slide type sample injector 16, and an unnecessary portion is discharged to the drain by sliding the injector 16. IC reactor 1
Similarly, at 0, the sample is the slide type sample injector 18
The necessary amount is injected by and the unnecessary portion is discharged to the drain.

In order to supply a carrier gas containing oxygen, a cylinder 20 is filled with pure oxygen gas or high-purity air excluding CO ₂ and hydrocarbons, and the gas from the cylinder 20 is used as a carrier gas at a gas flow rate. It is supplied via the control unit 22. The carrier gas is supplied to the combustion oxidation reaction section 8 or the sample introduction section 26 of the solid sample by the switching valve 24.
In the sample introduction unit 26, a solid sample such as soil or sludge is put on a boat 28 made of platinum or quartz and inserted into the combustion tube 30. Reference numeral 32 is an insertion rod into which the boat 28 is inserted. The combustion tube 30 is filled with an oxidation catalyst 34, and a heating furnace (heats up to about 900 ° C.) 36 around the combustion tube 30.
Is arranged. The carbon content generated from the solid sample placed on the boat is sent to the oxidation catalyst 34 together with the carrier gas containing oxygen, and is burnt and oxidized to become CO ₂ gas.

The gas from the combustion oxidation reaction section 8 of the aqueous solution sample introduction section is sent from the IC reactor 10 to the dehumidification gas processing section 42 through the blank check ultrapure water trap 40 and from the combustion tube 30 of the solid sample introduction section. This gas is also sent to the same dehumidifying gas processing unit 42. The gas dehumidified in the dehumidification gas processing unit 42 is guided to the measurement cell of the NDIR 46 by the switching valve 44. A cell 48a having a long cell length and a cell 48b having a short cell length are arranged in series in the NDIR 46 as a measurement cell with respect to the measurement light beam. The cell 48a is generally used as a measurement cell for a liquid sample, the optical path length of the measurement light is, for example, 200 mm, and the cell 48b is generally used as a measurement cell for a solid sample, and the optical path length of the measurement light is, for example, 1 mm.
Is. The gas that has passed through the dehumidifying gas processing unit 42 is a switching valve 44.
Leads to either cell 48a or 48b.
On the other hand, the carrier gas flows from the gas flow rate control unit to the switching valve 44.
After that, the gas for measurement is introduced as a purge gas into the other cell to which the gas for measurement is not introduced. Reference numeral 40 is for preparing ultrapure water containing no carbon for blank measurement and introducing it into the measuring apparatus via the sample injector 2.

The signal from the detector of the NDIR 46 is guided to the data processing section 50 and processed there. Reference numeral 52 is a keyboard, 54 is a liquid crystal display, and 56 is a printer.
The data processing unit 50 can also be connected to a computer, for example via an RS-232C connector. FIG.
A region surrounded by a two-dot chain line is an organic carbon measuring device assembled for measuring an aqueous solution sample, and the carrier gas cylinder 20, the solid sample introducing part and the switching valve 44 are connected to the outside of the organic carbon measuring device. It means that it is done. However, the structure is not limited to this, and the solid sample introducing part and the switching valve may be integrally assembled with the organic carbon measuring device.

Next, the operation of the embodiment shown in FIG. 1 will be described. When measuring an aqueous solution sample, the carrier gas switching valve 24 is switched to the aqueous solution sample side, and the switching valve 4
4 is switched so as to guide the measuring gas to the measuring cell 48a having a long optical path length. In the measurement of total carbon, the aqueous solution sample 6 is sampled by the sample injector 2 and injected into the combustion tube 12. Combustion tube 1
In 2, the total carbon in the aqueous solution sample is oxidized through the oxidation catalyst 13 to become CO ₂ gas, and together with the carrier gas, is passed through the dehumidifying gas treatment unit 42 and guided to the measurement cell 48a having a long optical path to measure the total carbon (TC). To be done. A carrier gas is introduced as a purge gas into the measuring cell 48b having a short optical path length. In the measurement of inorganic carbon, the aqueous solution sample 6 is collected by the sample injector 2 and injected into the IC reactor 10. In the IC reactor 10, inorganic carbon is generated as CO ₂ gas and is introduced together with the carrier gas through the dehumidifying gas treatment section 42 into the measuring cell 48a having a long optical path length to measure the inorganic carbon (IC). Total organic carbon (TOC) is calculated as TOC = TC-IC.

On the other hand, when measuring a solid sample, the carrier gas switching valve 24 is switched so as to guide the carrier gas to the heating tube 30, and the switching valve 44 guides the measuring gas to the measuring cell 48b having a short optical path length. Switch to. When the weighed solid sample is placed on the boat 28 and heated, the CO ₂ gas generated in the heating pipe 30 is guided to the NDIR 46 from the dehumidifying gas processing unit 42 together with the carrier gas and detected. A carrier gas is introduced as a purge gas into the measuring cell 48a having a long optical path. In the case of a solid sample containing a very small amount of carbon, the measurement gas may be introduced into the measurement cell 48a having a long optical path length in order to increase the sensitivity. Even if the sample is an aqueous solution, the TOC of% order
On the contrary, in the case of a sample containing, the measuring cell 48b having a short optical path length can be used to lower the sensitivity. By doing so, a wider measurement range can be obtained.

FIG. 2 shows another embodiment. In FIG. 2, the carrier gas is simultaneously flowed through the gas flow rate control unit 22 to the combustion tube 12 of the aqueous solution sample introducing section and the combustion tube 30 of the solid sample introducing section. The gas from the flow path for the liquid sample and the gas from the flow path for the solid sample are different from each other in the dehumidifying gas processing unit 42.
a, 42b, the gas from the liquid sample flow path is guided to the measurement cell 48a having a long optical path length of the measurement light beam, and the gas from the solid sample flow path is a measurement cell 48b having a short optical path length of the measurement light beam. Have been led to. At the time of measurement, either an aqueous solution sample or a solid sample is introduced into this carbon measuring device, and the generated gas is introduced into one of the measuring cells, but only the carrier gas is switched from the other sample introducing part where no sample is introduced. It is introduced into the measuring cell as purge gas through the valve 44 and prevents the invasion of the atmosphere.

In FIG. 2, the dehumidifying gas processing section 42 is further added.
a, 42b and the measuring cell 48a, 48b between the switching valve 4
4 are arranged. By this switching valve 44, both the gas from the liquid sample flow path and the gas from the solid sample flow path can be led to both of the two measurement cells 48a and 48b. Normally, the switching valve 4 is arranged so that the gas from the aqueous solution sample is guided to the measuring cell 48a having a long optical path length, and the gas from the solid sample is guided to the measuring cell 48b having a short optical path length.
4 is set. However, the switching valve 44 can be switched according to the carbon concentration in the sample.

[0015]

INDUSTRIAL APPLICABILITY In the present invention, the NDIR is used as the CO ₂ detector.
Since the measurement cells having different optical path lengths with respect to the measurement light flux are arranged in series with respect to the measurement light flux,
It becomes possible to perform measurement under optimum measurement conditions (carbon concentration and sample amount) for each of the aqueous solution sample and the solid sample with the carbon measuring device on the table. Also, when used as an aqueous solution sample or a solid sample, it is possible to perform measurement in a wider measurement range than before by properly using two types of measurement cells depending on the carbon concentration and sample amount.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment.

FIG. 2 is a configuration diagram showing another embodiment.

[Explanation of symbols]

 2 sample injector 4 switching valve 6 aqueous solution sample 8 combustion oxidation reaction part for aqueous solution sample 12 combustion pipe 20 carrier gas cylinder 24 switching valve 26 combustion oxidation reaction part for solid sample 30 combustion pipe 44 switching valve 46 NDIR 48a, 48b measurement cell

Claims (2)

[Claims] 1. An organic carbon measuring apparatus equipped with a carrier gas supply unit, a sample injection unit, a combustion oxidation reaction unit, and a CO ₂ detection unit for measuring total organic carbon in an aqueous solution sample, and a combustion oxidation reaction for a solid sample. the carbon content of the solid sample with a solid sample introduction portion for guiding together with the carrier gas as carbon dioxide into the CO ₂ detector in parts, measuring beam two measuring cells having different optical path lengths of the measuring light beam in the CO ₂ detector Using a non-dispersive infrared gas analyzer arranged in series to the measurement sample, the gas in the aqueous solution sample measurement channel is guided to the measurement cell with a long optical path length, and the gas in the solid sample measurement channel is measured with a short optical path length. Carbon measuring device configured to lead to. 2. A combustion oxidation reaction for a solid sample is applied to an organic carbon measuring device equipped with a carrier gas supply unit, a sample injection unit, a combustion oxidation reaction unit and a CO ₂ detection unit for measuring total organic carbon in an aqueous solution sample. Part is provided with a solid sample introduction part for guiding carbon content in the solid sample to carbon dioxide together with a carrier gas to the CO ₂ detection part, and the CO ₂ detection part measures two measurement cells having different cell lengths with respect to the measurement light flux. Using a non-dispersive infrared gas analyzer placed in series with the light flux,
Carbon measuring device provided with a switching means capable of switching and guiding the gas in the channel under measurement between the aqueous solution sample measurement channel and the solid sample measurement channel and the CO ₂ detection part .