JPH02179455A - Total organic carbon analyzer - Google Patents

Abstract

PURPOSE:To make the amount of specimen injection constant regardless of the concentration of carbon and to make it possible to perform highly reliable measurement by connecting a flow-path switching mechanism between a carbon dioxide transformer and non-dispersion type infrared-ray gas detector, and selecting a flow path. CONSTITUTION:When a specified amount of sample solution is injected into a combustion furnace, organic and inorganic carbons in the solution are transformed into carbon dioxide gas. The carbon dioxide gas intactly passes through an inorganic carbon reaction furnace 12 and flows into a non-dispersion type infrared-ray gas detector 31 through a path which is selected with a range switching mechanism 20. After the concentration of the gas is measured, the same sample is injected into the reaction furnace 12 by the same amount. Only the inorganic carbon in the sample is transformed into carbon dioxide gas. The carbon dioxide gas flows into the detector 31 through the mechanism 20. The mechanism 20 can select a path through which the sample can directly flows in and a path wherein the sample is divided at a constant ratio so that one is made to flow directly and the other is made to flow through a carbon- dioxide-gas absorbing pipe 27. When the sample has the high concentration, the sample is diluted so as to prevent the decrease in accuracy of the detector 31. Thus the accurate measurement can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides an apparatus for converting all organic carbon, inorganic carbon, and all carbon contained in an aqueous solution into carbon dioxide gas for analysis.

(Prior art) To measure organic carbon in an aqueous solution, the sample solution is usually placed in a combustion furnace and a reaction furnace to convert all organic carbon and inorganic carbon into carbon dioxide gas, which is then detected using non-dispersive infrared gas detection. However, since the practical detection range of non-dispersive infrared detectors is limited, the injection amount of the sample is adjusted according to the total organic carbon concentration in the solution and flows into the detector. Operation is required to keep the concentration of carbon dioxide gas within the measurement range.

(Problems to be Solved) Therefore, there are problems in that it is necessary to prepare multiple types of microsyringes for sample injection, and furthermore, it is necessary to create a test line to correct measurement errors for each microsyringe.

(Means for Solving the Problems) In order to solve such problems, in the present invention, a flow path switching valve is connected between the carbon dioxide conversion furnace and the non-dispersive infrared gas detector, and the carbon dioxide gas is Selecting a flow path that allows MWi of fluid from the conversion furnace to flow into the detector, and a flow path that distributes the fluid at a fixed ratio so that one of the fluids flows into the detector and the other flow into the detector via the carbon dioxide absorption means. made possible.

(Example) The details of the present invention will be described below based on illustrated examples.

FIG. 1 shows one embodiment of the present invention, in which the reference symbol in the figure is a carbon dioxide conversion furnace, which is equipped with a sample inlet 1 at the top, a high-purity air source 2 at one end, and a high-purity air source 2 at the other end. A combustion furnace 6 is constructed by housing a container 4 having a discharge port 3 in a heating furnace 5 that heats it to a temperature sufficient to thermally decompose organic carbon and react with high-purity air, for example 680°C, and a sample injection lower at the upper end. and is connected to the exhaust port 3 of the combustion furnace 6 via a drain separator 8 at one end,
The other end is connected to a range switching mechanism 20 (described later) through a drain separator 9, and an inorganic carbon reactor 12 is provided in which a container 10 containing a catalyst 15 is housed in a furnace 11 that heats it to, for example, 150°C. The furnace 6 is configured to selectively convert all carbon contained in the sample, and the reactor 12 selectively converts only inorganic carbon into carbon dioxide gas.

Reference numeral 2o in the figure is the range switching mechanism described above, and a flow path switching valve 2 that can select a plurality of flow paths, eight flow paths in this embodiment.
1 yen! , to connect the carbon dioxide conversion furnace I and the non-dispersive gas analyzer 31, and to form first, second, and third switching channels (indicated by ... in the figure, respectively). ,
The first flow switching channel (...) is equipped with a tube 22 that does not change the pipe resistance of the entire analysis system, and the second and third switching channels (-===') are each Resistance pipes 23 and 24 having different pipe resistances are connected, and a carbon dioxide absorption pipe 27 containing a carbon dioxide absorbent, for example, soda asbestos is connected from the inflow side upstream of the resistance pipes 23 and 24 through a pipe 25 and 26. The gas is configured to flow into a non-dispersive infrared gas detector 31 . Note that the reference numeral 32 in the figure indicates the output device tu.

In this example, when a specified amount of the sample solution is injected into the combustion furnace 6 using a microsyringe, the organic and inorganic carbon in the sample undergoes an oxidation reaction with oxygen in the high-purity air that also serves as a carrier gas, resulting in carbon dioxide gas 1. This will be converted. This carbon dioxide gas passes through the inorganic carbon reactor 12 as it is, flows into the range switching mechanism 20 together with high-purity air, and is diluted via the selected flow path, in this case the first flow path. The gas flows into the non-dispersive infrared gas detector 31 without any interference.

When the concentration measurement for total organic carbon is completed, the same sample is injected by -j1 into the inorganic carbon reactor 12.12. The inorganic carbon contained in the sample is the catalyst 1.
5 is converted into carbon dioxide gas, and the high purity air flowing through the combustion furnace 6 flows into the detector 31 through the range switching mechanism 20.

The concentrations measured by these first and second steps are:
Since 2 represents the total carbon concentration and inorganic carbon concentration, the concentration of organic carbon in the sacsiple can be determined by calculating the difference (LI 12).

On the other hand, when analyzing a solution containing organic carbon at a high concentration, for example, 10 times the concentration, the same amount is measured using a microsyringe that can perform the same measurement as in the case described above, while the range switching mechanism 20 is Switch to the second or third flow path and select a dilution rate of 10 times.

When the sample is injected into the combustion furnace 6 in this state, the carbon dioxide gas generated here flows into one resistance pipe, for example 23, of the range switching mechanism 20 via the inorganic carbon reaction furnace 12.

By the way, since a bypass path is formed by the pipe line 25 on the upstream side of the resistance pipe 23, the fluid resistance R of the resistance pipe 23 and the fluid resistance R of the pipe line 25 and the carbon dioxide absorption pipe 27 are
Distribution ratio R, / (R, 10R) determined by 2, R2/
(R, 10R) (distributed from this. As a result, among the carbon dioxide gas that has flowed into the range switching mechanism 20, R2/ (
R, +R) (length or detector, and the remaining R1/(day,
10R) is absorbed by the carbon dioxide absorption tube 27 and flows into the detector 31 as a high-purity air stream.

Needless to say, since the amount of carbon dioxide gas contained in high-purity air is extremely small, there is almost no change in the flow rate of gas flowing into the detector 31.

As a result, carbon dioxide gas is injected into the detector at a dilution rate determined by the fluid resistance of the resistance tube 23.
Detector 31 performs concentration measurements with high accuracy.

In this way, at the stage when the measurement at 1 per total carbon is completed, the same amount of the same sample is injected into the inorganic carbon reactor 12 without changing the range switching mechanism 20. As a result, inorganic carbon in the sacsiple can also be detected at the same dilution rate.

By correcting the difference between the two measurement results obtained in this way with the dilution rate, the non-dispersive infrared gas detector 30
It becomes possible to measure with high accuracy even a highly concentrated sample that would cause a decrease in accuracy.

In this example, dilution is also performed when measuring inorganic carbon, but if the concentration of inorganic carbon is low, normal measurement, that is, measurement via tube 22 may be sufficient.

[Example] Using 300 microliters of factory effluent prepared to pH 2 as a sample, the dilution rate was set to 10 times using the range switching mechanism, and total organic carbon was measured three times. As shown in Figure 2H, concentration 16
A value of 9.9 ppm could be obtained.

On the other hand, for comparison, when the same waste liquid was measured using the above-mentioned 1/10, that is, 30 microliters, using the conventional method, that is, without dilution, the concentration was 170.41)P.
A measurement result of I (II) was obtained. In the figure, I indicates a measurement result using a standard solution with a total organic carbon concentration of 200 ppm.

Therefore, according to the present invention, it is possible to increase the amount of sample to be measured, and at least it is possible to measure the sample with higher accuracy than the conventional method.

(Effects) As explained above, in the present invention, a flow path switching valve is connected between a carbon dioxide conversion furnace and a non-dispersive infrared gas detector, and fluid from the carbon dioxide conversion furnace is directed to the detector. Since it is possible to choose between a channel that allows direct flow into the sample and a channel that distributes the flow into the detector at a fixed ratio and the other flow channel through the carbon dioxide absorption means, the carbon concentration in the sample can be controlled. The injection amount of the sample can be kept constant regardless of the
To prevent measurement errors and enable highly reliable measurements.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a diagram showing an example of analysis results using the same device and a conventional device. ■...Carbon dioxide conversion furnace 2...High purity gas source 6...Combustion furnace 12...Inorganic carbon reactor 20...Range switching mechanism 23, 24...Resistance Pipe 27... Carbon dioxide absorption pipe

Claims (1)

[Claims] A flow path switching valve is connected between the carbon dioxide conversion furnace and the non-dispersive infrared gas detector, and the fluid from the carbon dioxide conversion furnace is distributed at a fixed ratio with a flow path that directly flows into the detector. A total organic carbon analyzer in which one can be selected from a flow path that flows into the detector and the other flow path that flows into the detector via a carbon dioxide absorption means.