Application Note AN-PAN-1040

火力発電所の冷却水に含まれるアンモニアの測定
Thermal power plants require enormous

cooling water circuit will contaminate the highamounts of water, using high purity steam atpurity water in the boiler, causing major

high pressure to rotate turbines. A separate

problems and necessitating a shutdown forcooling water circuit is implemented, helping toplant maintenance. Monitoring NH 3 online inform a vacuum when the steam condenses after

cooling water with a process analyzer can signal

the turbines. Maintaining this vacuum withearly problems in a plant before significant

optimal condensation parameters is critical forintermediation is necessary.

the power plant efficiency.

This Process Application Note presents a way to

The copper condensers are susceptible toclosely monitor the NH3 concentration in coolingcorrosion by ammonia (NH3). Small cracks in thewater of power plants to ensure protection ofcondenser combined with the large pressure

expensive company assets (e.g. pipes, boiler, anddifferential between the steam circuit and themore) and helps to safeguard plant operations.

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INTRODUCTIONThermal power plants require enormous

1013, AN-PAN-1038), is classified as either once-amounts of water to convert energy fromthrough or recirculating (dry cooling is not

generated heat to electricity, using high purity

discussed here). The growing number ofsteam at high pressure to rotate turbines. The

environmental guidelines and thermal discharge

steam loses energy and condenses, forming alimits has forced many plants to use closed

vacuum after the turbines, and the re-recirculating cooling water circuits, reducing thecondensed vapor is sent back to the boiler forcooling water needs by about 95% compared toreuse. Maintaining this vacuum with optimal

once-through cooling systems. The heat fromcondensation parameters is critical for thethe condenser can dissipate in a number ofpower plant efficiency.

manners, most commonly by an evaporative

Cooling water is used in a separate water circuit

cooling tower (Figure 1). Only small amounts of

to exchange heat from the condenser to themakeup water are required to replace

ambient surroundings. Water sources for coolingevaporative, drift, and blowdown losses in

can range from seawater, lakes, and rivers, to re-recirculating cooling water circuits. The coolingtreated municipal wastewater (MWW). Thewater chemistry is primarily maintained tocooling water circuit, discussed in otherinhibit scale formation and microbial growth

Metrohm Process Application Notes (AN-PAN-(fouling) as well as control corrosion.

Figure 1. Example schematic of a wet recirculating cooling water system for a thermal power plant.

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Copper (Cu) alloys are now used almost

mg/L NH 3 must be adhered to in order toexclusively in condensers of the water-steam

prevent severe corrosion. The result is increasedcircuit. The drawback is the susceptibility of

Cu concentration in effluents or othercopper and its alloys to corrosion by NH 3 .

discharges, which is of environmental concern.

Ammonia is also nutritional for microbes, which

Corrosion can also cause leaks and catastrophic

cause biological fouling. Ammonia stripping

failure in the piping. Small leaks and cracks

towers can be implemented on site to remove a

combined with the large pressure differential

significant percentage of NH3 via water-to-air

between the steam circuit and the cooling waterstripping, otherwise water treatment iscircuit will contaminate the high purity water innecessary. The cooling tower itself can strip thethe boiler, causing major problems andvolatile NH3 at optimal pH levels. According tonecessitating a shutdown for plant

the Electric Power Research Institute (EPRI), inmaintenance.

systems with copper alloys an upper limit of 2

Corrosion of Cu and its alloys can be inhibited byadding triazoles to form sparingly solublecompounds on the surface of the metal. Routine
system chlorination against biological foulingwill reduce ammonia levels somewhat as
chloramines are formed. Corrosion products andother impurities can be removed by chemicalcleaning. However, it is clear that ammonia is
detrimental to the cooling water circuit andmust be treated or otherwise removed before
Cu corrosion can occur. Metrohm Process
Analytics offers multiple online process

Figure 2. Trend chart of ammonia (NH3) showing a spike

analyzers which can measure NH 3 in coolingin concentration over a period of 130 days, which could

water of power plants, alerting the Chemicallead to possible corrosion. The dashed lines are control
measure guides, which can be changed depending onDistribution System (CDS) to add more corrosion

your process requirements.

inhibitors, chlorine, or other treatment
chemicals to the circuit before extreme damage
can occur.

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APPLICATION
Online monitoring of the ammonia content ispossible with either the 2060 Process Analyzer
or with the 2026 Titrolyzer from Metrohm
Process Analytics (Figure 3). An ammonia ionselective electrode (NH 3 -ISE) is used in thisapplication for quick, simple, and accurate
online analysis of NH3 concentrations in coolingwater. After sampling, a Total Ionic Strength
Adjustment Buffer (TISAB) solution is added toadjust the pH to 11 or higher, and the NH 3
concentration in the sample is determined using
Figure 3. Some of the Metrohm Process Analytics

the dynamic standard addition method.

analyzers capable of determining the ammonia

Typical range 0–100 mg/L NH3concentration online. Left: 2060 Process Analyzer, right:
2026 Titrolyzer.

REMARKSLower concentrations of ammonia can be

desulfurization process, boric acid in cooling

analyzed online with colorimetric or ion

water Pressurized Water Reactors (PWRs),

chromatographic methods, also available fromultratrace measurements of iron (Fe) and Cu,

Metrohm Process Analytics. Other online

rich/lean amine concentration and CO 2

applications are available for the energy andcaptured in Carbon Capture Plants, and many

power industry such as: silica in boiler feedmore.

water, calcium and sulfate in the flue-gas

FURTHER READING
Monitoring corrosion in power plants: online(Alkalinity) in cooling water

ultratrace analysis of Fe and Cu

Online monitoring of sodium in industrial power

2026 Ammonia Analyzer

plantsPower generation: Analysis of the m value

BENEFITS FOR TITRATION IN PROCESS- Safe working environment and automated- Save money by reducing downtime:sampling

analyzer sends alarms for out-of-- Protect valuable company assets (e.g. pipes,specification values which inform thePWR, and turbines, which are prone tooperator sooner

corrosion)www.metrohm.com

4CONTACT

メトロームジャパン株式会
社
143-0006 東京都大田区平和島6-1-1
null 東京流通センター アネックス9階

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metrohm.jp@metrohm.jp

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CONFIGURATION
2026 Titrolyzer
2026 Titrolyzer は、高精度ヒュレットシステムおよひ高性能電極を用いて電位差滴定を行います。様々な滴定には、酸/塩基滴定、酸化還元滴定、沈殿滴定なとか含まれます。変曲点自動検出技術は、ほとんとのアフリケーションて利用することかてきます。インラインセンサーか故障した状況ても、pH値の測定にアナライサーを用いることかてきます。
さらに、2026 Titrolyzer は、高精度ヒュレットおよひ高性能イオン選択性電極 (ISE) を用いて動的標準添加メソットを行うことかてきます。このメソッ
トにては、動的ティファレンシャルアフローチを用いることて、標準添加容量を実際のサンフル濃度に合わせることかてきます。さらに、複数の範囲におけるイオン選択性電極スローフ値か考慮されます。
すなわち、イオン選択性電極をその最低もしくは最高測定領域に適応させることかてきるということてす。付随して行われる温度測定により、分析結果に与え得る温度の影響を排除します。
2026 Titrolyzer は、化学、石油化学、半導体、環境、鉱業、鉄鋼や金属、飲料水なとの幾つかの市場に最適てす。
選択されたアフリケーションに含まれるもの:- 酸性またはアルカリ性溶液- 塩化物- 過酸化水素- 硬度- シアン化物-銅- フッ化水素
- pH
- なと

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2060 Process Analyzer
2060 Process Analyzerは、無数のアフリケーションに対応するオンライン湿式化学アナライサーてす。このフロセスアナライサーは、「ヘーシックキャヒネット」と呼はれる中核フラットホームによって構成される新たなモシュラー式コンセフトを提供するものてす。
ヘーシックキャヒネットは、2つの部分から構成されます。上部はタッチスクリーンと産業用PCを含みます。下部には、実際の分析のためのハートウェアか格納されるフレキシフルな湿式部か含まれます。
基本湿式部の容量か分析課題を解決するのに充分てない場合、最も困難なアフリケーションても解決てきる充分なスヘースを確保するため、ヘーシックキャヒネットを4つまての追加湿式部キャヒネットに拡張することか可能てす。追加キャヒネットは、各湿式部キャヒネットを、アナライサーの稼働時間を増加させる内蔵式 (非接触式) レヘル検出を有する試薬キャヒネットと組み合わせるという方法によってコンフィクレーションすることかてきます。
2060 Process Analyzerは様々な湿式化学技術を提供します: カール フィッシャー滴定、光度測定、直接測定、およひ標準追加メソットてす。
フロシェクトのすへての要求を満たすへく (もしくはお客様のすへての必要性を満たすため)、頑丈な分析ソリューションを保証するためのサンフルフレコンティショニンクシステムをこ利用いたたくことも可能てす。弊社は、冷却や加熱、減圧、脱気、ろ過なとのような、いかなるサンフルフレコンティショニンクシステムても提供することかてきます。

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