JPH10104220A - Combustion-oxidation type toc meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent highly sensitive measurement from being hampered by error caused by measuring an impurity or carbon dioxide (CO2 ) contained in carrier gas without being distinguished from carbon dioxide to be transformed from a sample. SOLUTION: A carbon dioxide gas absorbing material is melted in water in a humidifier 1, utilizing the humidifier 1 provided in the supply patg for the carrier gas introduced into a total carbon combustion tube 2. Thus, an impurity or carbon dioxide in carrier gas flowing in the humidifier 1 is absorbed-removed in the humidifier 1 and the cause of measuring error is eliminated. Further, the whole or a part of the humidifier 1 is formed of transparent material, and a crystal of calcium hydroxide (Ca(OH)2 ) is used as a carbon dioxide absorbing material to be added to water in the humidifier 1. Thus, since calcium hydroxide water solution shows alkalinity, it absorbs the impurity or carbon dioxide in carrier gas flowing in the humidifier 1. As a result, insoluble calcium carbonate (CaCO2 ) is formed, and water becomes cloudy. Thus, the quality of the carrier gas can be confirmed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention is used as an indicator of organic pollution for monitoring water quality of rivers, lakes, marshes, marine plant wastewater and the like and for evaluating and managing wastewater treatment facilities, as well as for cooling water, boiler water, pure water, and the like. The present invention relates to a combustion oxidation TOC meter, which is a TOC (total organic carbon) concentration measuring device used for managing organic impurities such as water.

[0002]

2. Description of the Related Art As a TOC meter, a sample is injected into a TC combustion tube held at a high temperature together with a carrier gas, and is completely burned in an oxidation catalyst filled in the combustion tube to be converted into carbon dioxide to convert TC (total carbon). ) Determine the concentration, separately determine the IC (inorganic carbon) concentration in the sample using an IC reactor, and separately measure the TC concentration and the IC concentration separately using a non-dispersive infrared spectrometer (NDIR), and calculate the TC concentration from the TC concentration. TOC after subtracting IC concentration
A combustion oxidation TOC meter of a type that quantitatively measures the concentration is well known.

[0003] In such a combustion oxidation TOC meter, particularly in high-sensitivity measurement, in order to reduce and stabilize a blank measurement value (blank test value),
It is essential to moderately humidify the carrier gas supplied to the TC combustion tube, and a humidifier is usually provided in the carrier gas supply passage.

[0004]

However, in such a conventional combustion oxidation type TOC meter, a humidifier is provided in a carrier gas supply passage for high-sensitivity measurement to appropriately humidify the carrier gas. Even if the angle blank measurement value is lowered and stabilized, for example, if the carrier gas contains carbon dioxide (CO ₂ ), which is an impurity, it is distinguished from carbon dioxide converted from the sample. The measurement was performed together without the measurement, which caused an error and hindered the high-sensitivity measurement.

[0005] The present invention provides a combustion oxidation TOC capable of performing high-sensitivity measurement without being affected by carbon dioxide as an impurity even when the carrier gas contains carbon dioxide as an impurity.
The purpose is to provide a total.

[0006]

In order to achieve the above object, a combustion oxidation type TOC meter according to the present invention is provided in a supply passage of a carrier gas introduced into a TC combustion tube, and is referred to as humidification of the carrier gas. It uses a humidifier that only plays an essential role, and dissolves a carbon dioxide absorbent in the water in the humidifier. As a result, the carbon dioxide gas, which is an impurity in the carrier gas flowing into the humidifier, is absorbed and removed in the humidifier, thereby avoiding an error factor.

Further, the present invention uses a calcium hydroxide (Ca (OH) ₂ ) crystal as a carbon dioxide absorbent added to water in the humidifier, wherein the whole or a part of the humidifier is formed of a transparent material. In the combustion oxidation TOC meter, the aqueous solution of calcium hydroxide shows alkalinity, so that it well absorbs carbon dioxide, which is an impurity in the carrier gas flowing into the humidifier, and as a result, insoluble calcium carbonate (CaCO ₃ ) Produces
Since the water becomes cloudy, it is possible to confirm the degree of absorption of carbon dioxide.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a combustion oxidation TOC meter according to the present invention will be described below with reference to the drawings. In FIG. 1, high-purity air is usually used as a carrier gas. Pressure regulating valve provided in the supply passage of
The humidifier 1 flows into the humidifier 1 via a pressure gauge, a mass flow controller, a flow meter, and the like (all not shown).

As shown in FIG. 2, the humidifier 1 is a cylindrical glass container having a diameter of 45 mm and a height of 130 mm. Pure water is sealed in the humidifier 1 and calcium hydroxide is used as a carbon dioxide gas absorbent. (Ca (OH) ₂ ) Dissolved until the crystals were saturated. Therefore, the carrier gas flowing into the humidifier 1 is humidified by the pure water vapor (normal temperature), and the carbon dioxide gas, which is an impurity in the carrier gas flowing into the humidifier 1, is hydroxylated in the humidifier 1. Reacts with calcium aqueous solution,
Produces insoluble calcium carbonate (CaCO ₃ ). That is,
The aqueous solution of calcium hydroxide in the humidifier 1 shows alkalinity, absorbs carbon dioxide, which is an impurity in the carrier gas, and turns water turbid. The degree of the cloudiness is proportional to the carbon dioxide absorption rate, and the degree of carbon dioxide absorption can be visually recognized from the outside.

[0010] The carrier gas from which carbon dioxide as an impurity has been removed in this manner is supplied to the TC combustion tube 2, the IC reactor 4,
It flows in the order of a dehumidifier 5 and a detector 6 such as a non-dispersive infrared analyzer. The TC combustion tube 2 is placed in the TC furnace 7 and
The combustion tube 2 is filled with an oxidation catalyst 3 such as platinum or the like. The IC reactor 4 has a drain pinch valve 8, not shown,
An IC reaction solution of an aqueous solution of an inorganic acid such as phosphoric acid can be supplied into the reactor 4.

A predetermined amount of the measurement sample 9 is sucked by a sample injector (syringe pump) 11 through a multi-port valve 10 and injected into the TC combustion tube 2. The injected measurement sample 9 completely burns in the oxidation catalyst filled in the TC combustion tube 2 kept at a high temperature, is converted into carbon dioxide, passes through the IC reactor 4 and the dehumidifier 5, and is detected. Vessel (NDI
In R) 6, the TC (total carbon) concentration in the sample is measured.

Separately, the measurement sample 9 is a multi-port valve 1
A predetermined amount is aspirated by a sample injector (micro syringe) 11 through 0 and injected into the IC reactor 4. The injected measurement sample 9 has its inorganic carbon converted into carbon dioxide gas by the IC reaction solution, passes through the dehumidifier 5, and detects the carbon dioxide gas by the detector (NDIR).
At 6, the IC (inorganic carbon) concentration in the sample is measured.

The data processing unit 12 calculates the TOC concentration by subtracting the IC concentration from the TC concentration quantitatively measured in this way, and displays this on the display unit 13.

Reference numeral 14 denotes ultrapure water for blank check.

[0015]

Since the present invention is constructed as described above, a carrier gas having a low carbon dioxide concentration is originally required as the carrier gas of the combustion oxidation TOC meter and should be used. Even if a low-purity carrier gas containing a relatively large amount of carbon dioxide is used, the carbon dioxide in the carrier gas can be efficiently removed, and high-sensitivity measurement can be achieved. it can.
Further, when the carbon dioxide gas is absorbed in the humidifier, the water (aqueous calcium hydroxide solution) in the humidifier becomes cloudy in a relatively short period of time, which also serves as an alarm for the quality of the carrier gas.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a combustion oxidation TOC meter of the present invention.

FIG. 2 is a diagram showing an example of a humidifier used in the combustion oxidation TOC meter of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Humidifier 2 ... TC combustion tube 3 ... Oxidation catalyst 4 ... IC reactor 5 ... Dehumidifier 6 ... Detector

Claims (2)

[Claims] 1. A sample is injected together with a carrier gas into a TC combustion tube maintained at a high temperature, burned under an oxidation catalyst in the combustion tube and converted into carbon dioxide to obtain a TC concentration, and then separately sampled in an IC reactor. Of the combustion oxidation method for determining the TOC concentration from the TC concentration and the IC concentration.
In the OC meter, a humidifier for humidifying the carrier gas is provided in a supply passage of the carrier gas introduced into the TC combustion tube, and a carbon dioxide gas absorbent is dissolved in water in the humidifier. Combustion oxidation TOC meter. 2. The combustion oxidation according to claim 1, wherein the whole or a part of the humidifier is made of a transparent material, and calcium hydroxide crystals are dissolved in water in the humidifier. Formula TOC meter.