JP3976182B2 - Method for measuring the concentration of hydrogen peroxide - Google Patents

Description

【００２５】
実施例３
某製鉄所に図２のような試験水路を設けて、ムラサキイガイの付着期に海水を３ｔ／ｈｒ、６０日間流しながら、本発明の測定装置を用いた過酸化水素制御による貝付着防止の有効性を確認した。
試験１は、対照区とし過酸化水素は添加しなかった。
試験２は、過酸化水素を常に１ｍｇ／Ｌ連続添加した。
試験３は、過酸化水素を常に２ｍｇ／Ｌ連続添加した。
試験４は、本発明の測定装置による過酸化水素の濃度管理を実施した。すなわち、遮光を施し、測定部が白金−銀電極法である図１の測定装置を用いて、測定時以外は、測定部からサンプル導入部まで海水を通液した。Ｃ地点をサンプル導入部として２時間に１回自動分析して該地点での過酸化水素が１．０ｍｇ／Ｌとなるように注入量を制御した。滞留槽は、工場内の海水通過に要する時間を６０分と想定し、その中間地点と末端での効果を把握するために設けた。結果を表２に示す。
【００２６】
【表２】

【００２７】
Ｃ地点での過酸化水素濃度を測定し、１．０ｍｇ／Ｌとなるように薬注量を管理することによって、ムラサキイガイの付着を完全に抑制でき、また過酸化水素の使用量も２ｍｇ／Ｌを連続的に添加するよりも少量で済み、効果も優れていた。
【００２８】
【発明の効果】
本発明により、海水中の微量過酸化水素の濃度を、長期間連続的に、しかも精度良く分析することが可能となる。特に、海生生物の付着防止の目的で使用される過酸化水素濃度の測定に適用することで、単に分析が可能となったばかりでなく、付着防止のための注入量制御が可能となり、付着防止性能の向上、ひいては過酸化水素注入量の削減も可能となり、産業上の利用価値は極めて高いものである。
【図面の簡単な説明】
【図１】 本発明の測定装置
【図２】 実施例３の試験水路
【符号の説明】
１ サンプル導入部
２ 採水ポンプ
３ 測定部
４ 三方弁
５ 排出ポンプ
６ サンプル排出部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrogen peroxide concentration measuring device and a concentration measuring method. More specifically, for example, in a plant using seawater as a transient cooling water, when hydrogen peroxide is added to the cooling water for the purpose of preventing marine organism adhesion, the concentration of hydrogen peroxide contained in the water is continuously increased. The present invention relates to an apparatus and method for measuring automatically.
[0002]
[Prior art]
Power plants, steelworks, petrochemical plants, etc. use a large amount of seawater as cooling water, and many of these facilities are built in the inland sea or in the bay to avoid waves. However, when seawater is taken in inland seas and bays, marine organisms such as mussels, barnacles, bryozoans, and hydroworms that inhabit the seawater are put on the inner walls of seawater intakes, pipes and conduits, heat exchangers and condensers. Adhere to. These attached marine organisms grow and narrow the water passage, and further drop off from the attached portion such as the inner wall, thereby obstructing the water flow in the pipe and the heat exchanger and lowering the cooling efficiency. In addition, local turbulence and oxygen concentration cells are generated, causing various problems such as corrosion failure of metals.
[0003]
Therefore, a method for preventing the attachment of marine organisms using hydrogen peroxide or a hydrogen peroxide generator (hydrogen peroxide supply compound) in such a seawater system has been proposed (see Japanese Patent Publication No. 61-2439) and put into practical use. Note that the concentration of hydrogen peroxide necessary to prevent such adhesion is about 0.5 to 1.0 mg / L.
[0004]
As an analytical method for measuring hydrogen peroxide, titanium sulfate colorimetric method, enzyme (peroxidase) colorimetric method, iodine coulometric titration method and the like are known, but titanium sulfate colorimetric method is 1 mg / L. The analysis accuracy of the following trace hydrogen peroxide concentration is poor, and the enzymatic colorimetric method has a problem that it is not practical to adjust the color reagent every time it is analyzed. The iodine coulometric titration method and the platinum-silver electrode method have an analysis accuracy of a trace hydrogen peroxide concentration of 1 mg / L or less and can be continuously measured.
[0005]
However, an apparatus for continuously measuring hydrogen peroxide requires a sample introduction path. The pipe diameter of the sample introduction part is appropriately 0.5 to 5 mm from the practicality of the device, but it is difficult to suppress the growth of many marine organisms with a small amount of hydrogen peroxide. If it stays in the sample introduction part in a stationary state, in addition to the propagation of marine organisms, contaminants in the seawater also adhere to the inside as a secondary factor, resulting in blockage of the piping. In addition, the analysis accuracy is lowered, for example, the hydrogen peroxide in the seawater that should exist originally is decomposed when passing through the sample introduction part.
[0006]
Therefore, there has been no knowledge in the past regarding whether or not a small amount of hydrogen peroxide contained in seawater can be measured continuously and accurately for a long period of time.
[0007]
[Problems to be solved by the invention]
The present invention provides a measuring apparatus and a measuring method for detecting the concentration of hydrogen peroxide added to water mainly for the purpose of preventing adhesion of marine organisms continuously and accurately for a long period of time. Let it be an issue.
[0008]
[Means for Solving the Problems]
In view of the current situation and recognition as described above, the present inventors have conducted extensive research on a hydrogen peroxide concentration measuring device and a concentration measuring method. As a result, after measuring the hydrogen peroxide concentration in a sample, the measurement is performed at the sample introduction portion. Without retaining the sample, the sample introduction part to the measurement part are subjected to a state that prevents the growth of microorganisms, and by combining with a known method for measuring the concentration of hydrogen peroxide, it can be continuously and accurately in the water for a long period of time. The inventors have found that it is possible to measure the concentration of hydrogen peroxide even in a trace amount, and have reached the present invention.
[0009]
That is, the present invention uses a concentration of hydrogen peroxide contained in water when adding hydrogen peroxide to cooling water for the purpose of preventing adhesion of marine organisms in a plant using seawater as a transient cooling water. A method for continuous measurement, which includes a sample introduction unit, a measurement unit, and a sample discharge unit, and uses a device in which a water sampling pump is provided between the sample introduction unit and the sample discharge unit. ) And the method of measuring the concentration of hydrogen peroxide, which prevents the growth of microorganisms by passing the liquid as in (2) and preventing the measurement sample from staying.
(1) Measure the hydrogen peroxide concentration in the water by operating the water sampling pump so that the cooling water flows from the sample introduction part through the measurement part to the sample discharge part. (2) Intermittent except during measurement. Or continuously, tap water, water to which a bactericidal agent is added, or alcohol for disinfection is passed through the sample introduction section and the measurement section.
DETAILED DESCRIPTION OF THE INVENTION
The present invention can be used not only for hydrogen peroxide but also for inorganic peroxides such as perboric acid, percarbonate, and peroxysulfuric acid that can release hydrogen peroxide in water. In the present invention, the microorganism that prevents reproduction refers to a microorganism that exists in water and has the ability to decompose hydrogen peroxide.
[0011]
The sample introduction part of the present invention may be any point where marine organisms should be prevented from being attached, and the outlet of main equipment such as a heat exchanger and a condenser is particularly desirable. As a state for preventing the growth of microorganisms, it is possible to prevent the measurement sample from staying by passing the sample introduction portion in a liquid state other than during measurement.
[0012]
As an embodiment of the present invention, a sample introduction unit 1 is provided with a pump 2 that can send liquids in both directions, and a three-way valve 4 and a discharge pump 5 are provided between sample discharge units 6 (FIG. 1). ). In the apparatus of FIG. 1, the propagation of microorganisms can be prevented by preventing the measurement sample from staying from the sample introduction unit to the measurement unit by the following sequence.
(1) Introduce sample from sample introduction part Water sampling pump left → right, discharge pump ON, three-way valve left → right (2) Concentration measurement at measurement part (3) Sample introduction part from the measurement part to tap water and disinfectant Liquid sampling pump right → left, drain pump OFF, three-way valve up → left with added water or disinfecting alcohol, etc. Go to process (1) or to process (1) after stopping the pump for a certain time ]
In the present invention, pipes used for the sample introduction part and the sample discharge part are not limited in material and shape as long as they are inert to hydrogen peroxide. For example, commercially available Teflon (registered trademark) or polyethylene A manufactured tube or the like can be preferably used.
[0014]
In the present invention, in addition to the sequence described above, examples of a method for performing the process from the sample introduction unit to the measurement unit in a state that prevents the growth of microorganisms include a method of performing a sterilization treatment such as applying a bactericide to the sample introduction unit.
[0015]
As the disinfectant used in the above sequence and application, commercially available disinfectants such as hypochlorous acid, hypobromous acid, hypoiodous acid, and glutaraldehyde can be suitably used. Moreover, when passing the said liquid, either intermittent or continuous may be sufficient. In addition to the embodiment shown in FIG. 1, the liquid passing method may use a two-way valve or a three-way valve for a pump used for introducing or discharging a sample. A valve or the like may be used.
[0016]
In the present invention, it is preferable to shield the sample introduction part from light in order to prevent the growth of microorganisms. The light shielding method is not particularly limited, and a commercially available coated or colored tube may be used, or a method such as winding a vinyl tape directly around the tube may be used.
[0017]
The hydrogen peroxide analyzer of the present invention is not particularly limited as long as it can be continuously measured. Here, a hydrogen peroxide measuring apparatus based on iodine coulometric titration has already been put into practical use and can be suitably used. This measurement method is also a preferable method from the viewpoint that free iodine can be produced in a measurement sample after completion of measurement using the iodine coulometric titration method, and the sample introduction part can be sterilized with the free iodine.
[0018]
According to the present invention, a trace amount of hydrogen peroxide in seawater can be accurately analyzed over a long period of time. The lower limit of detection can be up to about 0.01 mg / L, but it can be measured with extremely high accuracy up to 0.1 mg / L, and sufficient quantitative accuracy can be obtained for the purpose of the present invention. It is also possible to automatically control the hydrogen peroxide injection amount by setting the upper and lower limits of the hydrogen peroxide concentration in the automatic analyzer and feeding back the analysis result data to the hydrogen peroxide injection point. .
[0019]
【Example】
EXAMPLES The present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
[0020]
Example 1
Seawater cooling water, which is the process water at the Sakai Steel Works, was used as a measurement sample, and the sample introduction unit was shielded from light and used in the measurement apparatus of FIG. The measurement frequency was once per hour, and the hydrogen peroxide concentration was continuously measured for 56 days. Except at the time of measurement, seawater cooling water was passed from the top of the three-way valve to the measurement part and the sample introduction part. An analyzer (manufactured by Hiranuma Sangyo) based on the principle of iodine coulometric titration was used for the measurement part. The same process water was measured once per week using an enzyme (peroxidase) colorimetric method, and the hydrogen peroxide concentration was measured. The results are shown in Table 1.
[0021]
Example 2
Under the same conditions as in Example 1, under the same conditions, tap water (clean water) was passed from the measurement part to the sample introduction part except during measurement. It was measured. The same process water was measured once per week using an enzyme (peroxidase) colorimetric method, and the hydrogen peroxide concentration was measured. The results are shown in Table 1.
[0022]
Comparative Example 1
Measured hydrogen peroxide concentration continuously for 28 days under the same conditions as in Example 1 except that no light was passed and water was not passed except during measurement. Finished because the concentration was less than 0.05 mg / L. In addition, the hydrogen peroxide concentration was measured for the same process water using an enzyme (peroxidase) colorimetric method with a measurement frequency of once a week. The results are shown in Table 1.
[0023]
Comparative Example 2
The hydrogen peroxide concentration was measured continuously for 28 days under the same conditions at the same site as in Example 1 except that water was not passed except during the measurement, and the hydrogen peroxide concentration on the 28th day was 0.05 mg / day. Finished because it was less than L. In addition, the hydrogen peroxide concentration was measured for the same process water using an enzyme (peroxidase) colorimetric method with a measurement frequency of once a week. The results are shown in Table 1.
[0024]
[Table 1]

[0025]
Example 3
The test water channel as shown in Fig. 2 is installed at the Sakai Steel Works, and the effectiveness of the prevention of shellfish adhesion by hydrogen peroxide control using the measuring device of the present invention while flowing seawater at 3t / hr for 60 days during the mussel adhesion period It was confirmed.
In Test 1, as a control, hydrogen peroxide was not added.
In Test 2, hydrogen peroxide was always added continuously at 1 mg / L.
In Test 3, hydrogen peroxide was always added continuously at 2 mg / L.
In Test 4, the concentration control of hydrogen peroxide was performed by the measuring apparatus of the present invention. That is, with the light shielded, seawater was passed from the measurement part to the sample introduction part using the measurement apparatus of FIG. 1 in which the measurement part was a platinum-silver electrode method except during measurement. Using point C as a sample introduction part, an automatic analysis was performed once every two hours, and the injection amount was controlled so that the hydrogen peroxide at the point was 1.0 mg / L. The staying tank was provided in order to grasp the effect at the intermediate point and the terminal, assuming that the time required for passing seawater in the factory was 60 minutes. The results are shown in Table 2.
[0026]
[Table 2]

[0027]
By measuring the concentration of hydrogen peroxide at point C and controlling the amount of drug injection so as to be 1.0 mg / L, adhesion of blue mussel can be completely suppressed, and the amount of hydrogen peroxide used is 2 mg / L. The amount was less than the continuous addition, and the effect was excellent.
[0028]
【The invention's effect】
According to the present invention, it is possible to analyze the concentration of trace hydrogen peroxide in seawater continuously for a long period of time with high accuracy. In particular, by applying it to the measurement of hydrogen peroxide concentration used for the purpose of preventing the adhesion of marine organisms, it is possible not only to analyze, but also to control the injection amount to prevent adhesion, preventing adhesion The performance can be improved and the amount of hydrogen peroxide injected can be reduced, and the industrial utility value is extremely high.
[Brief description of the drawings]
[Fig. 1] Measuring device of the present invention [Fig. 2] Test channel of Example 3 [Explanation of symbols]
1 Sample introduction part 2 Water sampling pump 3 Measurement part 4 Three-way valve 5 Discharge pump 6 Sample discharge part

Claims (2)

A method of continuously measuring the concentration of hydrogen peroxide contained in water when hydrogen peroxide is added to cooling water for the purpose of preventing attachment of marine organisms in plants that use seawater as a transient cooling water. The measurement is performed as shown in (1) below using an apparatus including a sample introduction unit, a measurement unit, and a sample discharge unit, and a water sampling pump provided between the sample introduction unit and the sample discharge unit. (2) A method for measuring the concentration of hydrogen peroxide, which prevents the growth of microorganisms by passing the liquid and preventing the measurement sample from staying.
(1) Measure the hydrogen peroxide concentration in the water by operating the water sampling pump so that the cooling water flows from the sample introduction part through the measurement part to the sample discharge part. (2) Intermittent except during measurement. Or tap water, disinfectant-added water, or rubbing alcohol through the sample introduction part and measurement part. 2. The method for measuring hydrogen peroxide according to claim 1, wherein the sample introduction part is shielded from light.

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