JP6083313B2 - Measuring device and measuring method for total hardness or magnesium hardness - Google Patents
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Description
本発明は、水中の全硬度又はマグネシウム硬度（マグネシウムイオン濃度）の測定に関するものである。 The present invention relates to the measurement of total hardness or magnesium hardness (magnesium ion concentration) in water.
水を利用するプラントを安全かつ効率よく運転するためには、そのプラントに適した水質管理を行うことが必要であり、そのためには水質分析が重要であり、特に水中の硬度を管理することは重要である。なお、硬度とは、水中のカルシウムイオン（Ｃａ２＋）およびマグネシウムイオン（Ｍｇ２＋）の合計の濃度を示す単位であって、ＣａＣＯ３に換算したｍｇ／Ｌで表わされる（ＪＩＳ硬度）。 In order to operate a plant that uses water safely and efficiently, it is necessary to perform water quality management suitable for the plant, and water quality analysis is important for that purpose. is important. The hardness is a unit indicating the total concentration of calcium ions (Ca 2+ ) and magnesium ions (Mg 2+ ) in water, and is expressed in mg / L converted to CaCO 3 (JIS hardness).
硬度成分のうち、マグネシウムは開放循環冷却水系の濃縮によりスケールとして付着することが知られている。特に、熱交換器でスケールの付着が進行すると、熱交換器における熱効率の低下や通水の悪化を引き起こし、放置すれば操業停止などの大きな障害の要因となるため、定期的な分析が求められている。 Among the hardness components, it is known that magnesium adheres as a scale by concentrating an open circulating cooling water system. In particular, if the scale adheres to the heat exchanger, the heat efficiency of the heat exchanger will decrease and the water flow will deteriorate, and if left untreated, it will cause major obstacles such as shutdown, so periodic analysis is required. ing.
現在までのところ、マグネシウム硬度を現場で連続的に測定する信頼性の高いセンサが提案されていない。例えば、特許文献１の第００２８段落には、精製水製造用の原水中のカルシウムイオン濃度をイオン電極を用いて測定することが記載されているが、マグネシウムイオン濃度の測定方法については記載されていない。そのため、現場で採取したサンプルを、例えばＪＩＳ Ｋ０１０１法に従ってＥＤＴＡ標準溶液による滴定でマグネシウムイオン濃度を測定している。 To date, no highly reliable sensor that continuously measures magnesium hardness in the field has been proposed. For example, paragraph 0028 of Patent Document 1 describes that a calcium ion concentration in raw water for producing purified water is measured using an ion electrode, but a method for measuring a magnesium ion concentration is described. Absent. Therefore, the magnesium ion concentration is measured by titrating a sample collected on site with an EDTA standard solution according to, for example, JIS K0101 method.
しかしながら、この滴定法による分析は手動で行うため、時間と労力を要する。特許文献２には発色試薬を用いた全硬度測定方法が記載されているが、測定に手間がかかる。
However, since the analysis by the titration method is performed manually, time and labor are required.
これら以外の方法として、２価陽イオン電極を用いる方法が検討されている。すなわち、２価陽イオン電極の電位より算出したカルシウムイオン濃度とマグネシウムイオンの濃度の和（全硬度）から、カルシウムイオン選択性電極の電位から求めたカルシウムイオン濃度を差し引くことでマグネシウムイオン濃度を算出する方法である。しかし、２価陽イオン電極は、測定値の信頼性が低く、実用に耐えられる性能を有していない問題がある（非特許文献１）。 As a method other than these, a method using a divalent cation electrode has been studied. That is, the magnesium ion concentration is calculated by subtracting the calcium ion concentration obtained from the potential of the calcium ion selective electrode from the sum (total hardness) of the calcium ion concentration and magnesium ion concentration calculated from the potential of the divalent cation electrode. It is a method to do. However, the divalent cation electrode has a problem that the reliability of the measured value is low and it does not have the performance to withstand practical use (Non-patent Document 1).
本発明は、水中の全硬度又はマグネシウム硬度を容易に測定することができる方法及び装置を提供することを目的とする。 An object of this invention is to provide the method and apparatus which can measure the total hardness or magnesium hardness in water easily.
本発明者らは、全国各地の開放循環冷却水系において２価陽イオン電極を用いて、全硬度を直接測定することを試みた。しかし、上述のように、２価陽イオン電極から直接算出した測定値と手分析（ＥＤＴＡ滴定法）による分析値との相関が悪く、実用上の使用は不可能であった（後述の比較例）。すなわち、２価陽イオン電極では全硬度やマグネシウムイオン濃度の直接測定が不可能なことを確認した。 The present inventors have attempted to directly measure the total hardness using a divalent cation electrode in open circulating cooling water systems in various parts of the country. However, as described above, the correlation between the measurement value directly calculated from the divalent cation electrode and the analysis value by manual analysis (EDTA titration method) was poor, and practical use was impossible (Comparative Example described later). ). That is, it was confirmed that direct measurement of total hardness and magnesium ion concentration was impossible with a divalent cation electrode.
本発明者は、任意の地域における年間のカルシウムイオンと全硬度又はマグネシウム硬度との比率を確認した結果、各地域毎にこの比率は一定であり、ある地域において開放循環冷却水系のカルシウム濃度を測定することにより、その地域の開放循環冷却水系の全硬度とマグネシウムイオン濃度を推定することが可能であることを知見した。本発明はかかる知見に基くものである。 As a result of confirming the ratio between the annual calcium ion and the total hardness or the magnesium hardness in an arbitrary region, the present inventor measured this calcium concentration in an open circulating cooling water system in a certain region. It was found that it was possible to estimate the total hardness and magnesium ion concentration of the open circulating cooling water system in the area. The present invention is based on such knowledge.
本発明の全硬度又はマグネシウム硬度の測定装置は、試料水のカルシウム硬度を測定可能であってその測定結果を出力する水質測定部と、予め測定したカルシウム硬度と全硬度との関係又はカルシウム硬度とマグネシウム硬度との関係の記憶および読み出しが可能な記憶部と、前記水質測定部から出力される測定結果と測定地域に応じて前記記憶部から読み出された係数とに基づいて演算を行い、前記試料水の全硬度又はマグネシウム硬度の推定値を出力する演算部とを有する。 The measuring device for total hardness or magnesium hardness of the present invention is a water quality measuring unit capable of measuring the calcium hardness of sample water and outputting the measurement result, and the relationship between calcium hardness and total hardness measured in advance or calcium hardness A storage unit capable of storing and reading the relationship with magnesium hardness, and performing a calculation based on the measurement result output from the water quality measurement unit and the coefficient read from the storage unit according to the measurement area, A calculation unit that outputs an estimated value of the total hardness or magnesium hardness of the sample water.
前記水質測定部は、カルシウムイオン電極を備えることが好ましい。 The water quality measurement unit preferably includes a calcium ion electrode.
本発明の全硬度又はマグネシウム硬度の測定方法は、水中のカルシウム硬度をカルシウムイオン電極で測定する工程と、このカルシウム硬度と測定地域に応じた係数とを用いて全硬度又はマグネシウム硬度を演算する工程とを有する。 The method for measuring the total hardness or magnesium hardness of the present invention includes a step of measuring calcium hardness in water with a calcium ion electrode and a step of calculating total hardness or magnesium hardness using the calcium hardness and a coefficient corresponding to the measurement region. And have.
対象とする水系において、カルシウム硬度と全硬度とは一定の関係にある。そのため、予めその地域のカルシウム硬度と全硬度又はマグネシウム硬度の関係を調べておくことにより、その地域における、水中のカルシウム硬度を測定すれば全硬度又はマグネシウム硬度を推定できる。なお、全硬度の推定値からカルシウム硬度測定値を差し引くことでもマグネシウム硬度を推定できる。 In the target water system, the calcium hardness and the total hardness have a certain relationship. Therefore, the total hardness or magnesium hardness can be estimated by measuring the calcium hardness in water in the region by examining the relationship between the calcium hardness and the total hardness or magnesium hardness in the region in advance. The magnesium hardness can also be estimated by subtracting the measured calcium hardness value from the estimated value of the total hardness.
本発明によれば、対象水系中のマグネシウム硬度を、精度良く簡便かつ迅速に連続して推定することができる。 ADVANTAGE OF THE INVENTION According to this invention, the magnesium hardness in object water system can be estimated continuously accurately, simply and rapidly.
以下、本発明についてさらに詳細に説明する。 Hereinafter, the present invention will be described in more detail.
全国の各地域に設置された開放循環冷却水系において、全硬度及びカルシウム硬度を測定したところ、地域によって硬度値は変化するが、全硬度とカルシウム硬度との比はその地域に応じ全測定期間（約１０ヶ月間）を通じてほぼ一定であることを見出した。これは、開放循環冷却水系で用いる補給水は、その地域の水道水、地下水又は工業用水もしくはそれらを処理した水であり、当該水中の全硬度及びカルシウム硬度は一年を通じてほぼ一定であるためである。主な地域のデータを挙げると、表１の通りである。 In the open circulation cooling water system installed in each region of the country, the total hardness and calcium hardness were measured, and the hardness value varied depending on the region, but the ratio of total hardness and calcium hardness depends on the region and the total measurement period ( It was found to be almost constant over a period of about 10 months). This is because the makeup water used in the open circulation cooling water system is local tap water, ground water, industrial water or water obtained by treating them, and the total hardness and calcium hardness in the water are almost constant throughout the year. is there. Table 1 shows the data of major regions.
従って、カルシウムイオン電極を用いてある地域の水系のカルシウム硬度を求めると、このカルシウム硬度をその地域のｂ／ａで除算する（カルシウム硬度にｂ／ａの逆数ａ／ｂを乗算する）ことにより全硬度が求まる。この全硬度からカルシウム硬度測定値を減算する（［全硬度］−［カルシウム硬度］を演算する）ことにより、マグネシウム硬度が求まる。 Therefore, when the calcium hardness of the water system of a certain area is obtained using the calcium ion electrode, this calcium hardness is divided by b / a of the area (by multiplying the calcium hardness by the reciprocal a / b of b / a). The total hardness is obtained. By subtracting the measured value of calcium hardness from this total hardness (calculating [total hardness] − [calcium hardness]), the magnesium hardness is obtained.
なお、ｂ／ａが一定であることから、マグネシウム硬度（ａ−ｂ）とカルシウム硬度（ｂ）との比（ａ−ｂ）／ｂも一定である。従って、地域に応じて［マグネシウム硬度／カルシウム硬度］比を予め求めておき、カルシウム硬度測定値に対しこの［マグネシウム硬度／カルシウム硬度］比を乗算することによってマグネシウム硬度を直ちに求めることもできる。 In addition, since b / a is constant, ratio (ab) / b of magnesium hardness (ab) and calcium hardness (b) is also constant. Therefore, the [magnesium hardness / calcium hardness] ratio can be determined in advance according to the region, and the magnesium hardness can be determined immediately by multiplying the measured calcium hardness by this [magnesium hardness / calcium hardness] ratio.
図１は全硬度又はマグネシウム硬度の測定装置のブロック図であり、カルシウムイオン電極１の検出信号がＡ／Ｄ変換器２でデジタル信号に変換され、コンピュータ３の演算部４に入力される。この演算部４は、入力部６から与えられる地域情報に応じて記憶部５から上記（ｂ／ａ）又は（ａ−ｂ）／ｂなどの係数値を読み出し、全硬度又はマグネシウム硬度の演算を行い、その結果を液晶などよりなる表示部７に表示する。なお、記憶部５に対しては、地域毎の上記係数値が予め入力部６から入力されている。上記の演算結果は通信回線を通じて管理センター等に送信されてもよい。
FIG. 1 is a block diagram of a measuring device for total hardness or magnesium hardness. A detection signal of a calcium ion electrode 1 is converted into a digital signal by an A /
以下、実施例及び比較例により本発明を具体的に示すが、本発明は下記実施例に限定されるものではない。 EXAMPLES Hereinafter, although an Example and a comparative example show this invention concretely, this invention is not limited to the following Example.
［比較例１］従来法データ
全国の開放循環冷却水系の冷却水サンプルを収集し、２価陽イオン電極にて測定した値とキレート滴定にて測定した全硬度の値を比較した結果を図２に示す。２価陽イオン電極および比較電極としてはオリオン社製９３−３２およびオリオン社製シングルジャンクション比較電極９０−０１をそれぞれ用いた。
[Comparative Example 1] Conventional method data Cooling water samples of the nationwide open circulation cooling water system were collected, and the result of comparing the value measured by the divalent cation electrode and the value of the total hardness measured by chelate titration was shown in FIG. Shown in As a divalent cation electrode and a reference electrode, Orion 93-32 and Orion Single Junction Reference Electrode 90-01 were used, respectively.
図２の通り、マグネシウムの測定値とキレート滴定値との間に相関関係は認められず、マグネシウムを用いたときには硬度測定値の信頼性は著しく低いことが認められた。 As shown in FIG. 2, there was no correlation between the measured value of magnesium and the chelate titration value, and it was confirmed that the reliability of the hardness measured value was remarkably low when magnesium was used.
［実施例１］
茨城県鹿島地区の実機循環冷却水について、年間を通じてカルシウム硬度（ｂ）と全硬度（ａ）とを滴定法により測定し、その結果を図２に示した。図２の通り、ｂ／ａ値は０．４８〜０．６３（平均０．５５）であり、ＣＶ値は５％の範囲内で収まっていた。
[Example 1]
For actual circulating cooling water in the Kashima area of Ibaraki Prefecture, calcium hardness (b) and total hardness (a) were measured by the titration method throughout the year, and the results are shown in FIG. As shown in FIG. 2, the b / a value was 0.48 to 0.63 (average 0.55), and the CV value was within 5%.
以上より、ｂ／ａ値は年間を通して一定であり、カルシウム硬度から全硬度を推定できることが確認された。 From the above, it was confirmed that the b / a value is constant throughout the year and the total hardness can be estimated from the calcium hardness.
そこで、ｂ／ａ＝０．５５を用い、カルシウム硬度から推定した全硬度と、実測全硬度との関係を求め、図４に示した。図４の通り、循環水、補給水とも、同一の直線状にあり、良好な相関関係を有していることが認められた。 Therefore, using b / a = 0.55, the relationship between the total hardness estimated from the calcium hardness and the measured total hardness was determined and shown in FIG. As shown in FIG. 4, it was recognized that the circulating water and make-up water are in the same straight line and have a good correlation.
以上より、キレート滴定により求めた値と本発明法により求めた値とがほぼ一致する結果が得られることがわかる。このように、本発明により水中の全硬度又はマグネシウム硬度を、連続して、精度良く、簡便に測定できることがわかる。 From the above, it can be seen that the result obtained by the chelate titration almost coincides with the value obtained by the method of the present invention. Thus, it can be seen that according to the present invention, the total hardness or magnesium hardness in water can be measured continuously, accurately and simply.
なお、実施例では、循環水をバッチでサンプリングしたものであるが、循環水ラインにバイパスを設け、そこに設置したカルシウムイオン電極や自動滴定装置の値をもとに全硬度の値を推定しても良い。また、オンラインで測定する場合には、測定結果に基づき、薬注制御機器やブロー制御機器と連携させても良い。 In the examples, circulating water was sampled in batches, but a bypass was provided in the circulating water line, and the total hardness value was estimated based on the values of the calcium ion electrode and automatic titrator installed there. May be. Moreover, when measuring online, based on a measurement result, you may make it cooperate with a chemical injection control apparatus and a blow control apparatus.
１ カルシウムイオン電極
４ 演算部
５ 記憶部
1
Claims (3)
予め測定したカルシウム硬度と全硬度との関係又はカルシウム硬度とマグネシウム硬度との関係の記憶および読み出しが可能な記憶部と、
前記水質測定部から出力される測定結果と測定地域に応じて前記記憶部から読み出された係数とに基づいて演算を行い、前記試料水の全硬度又はマグネシウム硬度の推定値を出力する演算部と
を有する全硬度又はマグネシウム硬度の測定装置。 A water quality measurement unit capable of measuring the calcium hardness of the sample water and outputting the measurement result;
A storage unit capable of storing and reading the relationship between the calcium hardness and the total hardness measured in advance or the relationship between the calcium hardness and the magnesium hardness;
A calculation unit that performs calculation based on the measurement result output from the water quality measurement unit and the coefficient read from the storage unit according to the measurement region, and outputs an estimated value of the total hardness or magnesium hardness of the sample water A measuring device for total hardness or magnesium hardness.
このカルシウム硬度と測定地域に応じた係数とを用いて全硬度又はマグネシウム硬度を演算する工程と
を有する全硬度又はマグネシウム硬度の測定方法。 Measuring calcium hardness in water with a calcium ion electrode;
A method for measuring total hardness or magnesium hardness, comprising calculating the total hardness or magnesium hardness using the calcium hardness and a coefficient corresponding to the measurement region.
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| JPS63159749A (en) * | 1986-12-24 | 1988-07-02 | Kurita Water Ind Ltd | Hardness detecting device |
| JP3401387B2 (en) * | 1996-05-21 | 2003-04-28 | 財団法人塩事業センター | Solution composition measurement system |
| JPH10276722A (en) * | 1997-04-04 | 1998-10-20 | M P G Kk | Food containing coral |
| JPH10332596A (en) * | 1997-05-27 | 1998-12-18 | Miura Co Ltd | Method for quantitative determination of metal ions |
| JP3301358B2 (en) * | 1997-08-27 | 2002-07-15 | 三浦工業株式会社 | Hardness indicator |
| JP2002112983A (en) * | 2000-10-05 | 2002-04-16 | Tanita Corp | Instrument for measuring ingested table salt |
| JP3868916B2 (en) * | 2003-03-17 | 2007-01-17 | 株式会社健康医学社 | Method for separating and extracting hardness component and nutritional supplement food containing hardness component |
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