什么是陽離子電導率？為什么它很重要？（中英文）
在公用事業(yè)行業(yè)，陽離子電導率測量可幫助工廠識別小問題，以便工廠人員能夠在問題發(fā)展成重大并發(fā)癥之前解決問題。
In the utility industry, cation conductivity measurements help plants identify minor problems so plant personnel can remedy the issues before they become major complications.
什么是陽離子電導率？它是如何工作的？
What is cation conductivity, and how does it work?
陽離子電導率是監(jiān)測蒸汽或水樣中污染物的最佳方法之一。它也被稱為離子交換后電導率 (CACE)、酸電導率和交換后電導率。
離子“種類”或離子存在于樣品流中，因為化合物在水中分解（溶解）。高工藝溫度會加速這一過程。其他測量方法用于識別系統(tǒng)中的其他污染物。
這些離子可以帶正電（陽離子）——包括鈉、銅、鐵、錳和氫——也可以帶負電（陰離子），如氯化物和硫酸鹽，它們特別令人擔憂，因為它們是腐蝕源。陽離子電導率將帶正電的離子從陽離子樹脂柱中的工藝流中分離出來。
例如，在發(fā)電廠中，工程師希望識別可能因冷凝器管泄漏而存在的鹽等污染物。鹽會溶解并產(chǎn)生 NA+ 和 Cl-。陽離子樹脂將捕獲帶正電的鈉離子，取代帶正電的氫離子，氫離子將與帶負電的氯離子結合生成 HCL 并增加電導率測量值，從而表明存在污染物。
Cation conductivity is one of the best ways to monitor for contaminants within a steam or water sample. It is also referred to as Conductivity after Ion Exchange (CACE), Acid Conductivity and After Exchange Conductivity.
Ionic “species” or ions are present in a sample stream because compounds break down (dissolve) in water. High process temperatures accelerate this process. Other measurements are used to identify other contaminants in the system.
These ions can be positively charged (cations) – including sodium, copper, iron, manganese and hydrogen – and negatively charged (anions), like chlorides and sulfates which are of particular concern as they are sources of corrosion. Cation conductivity separates the positively charged ions from the process stream in a cation resin column.
As an example, in a power plant, we wish to identify contaminants like salts that might be present as a result of a condenser tube leak. The salt will dissolve and create NA+ and Cl-. The cation resin will capture the positively charged Sodium ions, displace a positively charged hydrogen ion which will bond with the negatively charged chloride ion creating HCL and increasing the conductivity measurement value thereby indicating a contaminant is present.
為什么陽離子電導率在公用設施中如此重要？
Why is cation conductivity significant in a utility plant?
陽離子電導率可防止污染物在工廠中引起更嚴重的問題。
例如，當氯化鈉進入渦輪機并在渦輪葉片上形成沉積物，并且該渦輪機隨后在沒有任何干燥空氣保護的情況下關閉時，氯化鈉沉積物、空氣中的氧氣和水分的結合使氯離子變得具有高度腐蝕性并在渦輪葉片表面形成凹坑。隨著時間的推移，這些凹坑可能導致災難性的故障。
在高壓鍋爐（10 Mpag，1450 psig 及以上）中，氯化鈉污染會導致鍋爐管的嚴重腐蝕，從而導致水壁發(fā)生氫脆故障。陽離子電導率可以盡早發(fā)現(xiàn)這一問題，從而更大限度地提高工廠工藝中的清潔水并最大限度地減少停機時間。
Cation conductivity prevents contaminants from causing more significant issues in the plant.
For example, when sodium chloride enters a turbine and forms a deposit on the turbine blades and that turbine is later shut down without any dry-air protection, the combination of sodium chloride deposit, oxygen In the air and moisture allow the chloride ion to become highly corrosive and form pits on the turbine blade surfaces. Over time these pits can lead to catastrophic failures.
In high-pressure boilers (10 Mpag, 1450 psig and above) sodium chloride contamination can lead to aggressive corrosion of the boiler tubes leading to hydrogen embrittlement failures in the water walls. Cation conductivity can catch this problem early to maximize clean water in a plant’s processes and minimize downtime.
什么是陽離子樹脂柱？
What are cation resin columns?
陽離子樹脂柱通過使用帶負電的塑料珠捕獲溶液中的帶正電的離子，將陽離子交換為陰離子。
帶正電的陽離子與塑料珠上的功能組結合，取代釋放的氫離子。釋放的氫離子可以產(chǎn)生酸性溶液 - 這就是陽離子電導率有時被稱為酸電導率或陽離子交換后電導率 (CACE) 的原因。陽離子樹脂柱對污染物高度敏感，可以檢測到低濃度的污染物。
非反應性塑料柱的長度與直徑的比對于確保樹脂的適當流動、停留時間和體積很重要。
大多數(shù)陽離子交換樹脂都包含顏色指示劑，當樹脂耗盡（無法交換離子）時，它會改變顏色，不同的樹脂制造商使用不同的顏色指示劑染料，最常見的是深紫色或深紅色，耗盡時分別變?yōu)闇\棕色和淺紅色。
顏色變化依次發(fā)生，直到所有樹脂都耗盡。
當柱子中的所有樹脂都變色時，樹脂就無法再去除任何陽離子，陽離子會從柱子中流出，從而增加出口處的電導率?，F(xiàn)在應該用新樹脂或再生樹脂替換舊樹脂。
Cation resin columns exchange cations for anions by using negatively charged plastic beads to capture positively charged ions in a solution.
The positively charged cations bind to functional groups on the plastic beads, replacing a hydrogen ion which is released. The released hydrogen ions can create an acidic solution – that’s why cation conductivity is sometimes called acid conductivity or Conductivity after Cation Exchange (CACE). Cation resin columns are highly sensitive to contaminants and can detect low levels of them.
The length to diameter ratio of the non-reactive plastic column is important to ensure proper flow, residence time and volume of resin.
Most cation exchange resin includes a color indicator such that when the resin is exhausted (unable to exchange ions) it changes color, different resin manufacturers use different color indicator dyes most commonly deep purple or dark red, and change to light brown and light red, respectively, when exhausted.
The color change happens sequentially until all the resin is exhausted.
When all the resin in the column has changed color, the resin can no longer remove any cations and they can exit the column which increases the conductivity on the outlet. The resin should now be replaced with fresh resin or regenerated resin.
陽離子樹脂柱可用于哪些應用？
What applications are cation resin columns used with?
陽離子樹脂柱可用于多種應用，包括：
? 發(fā)現(xiàn)因發(fā)電廠腐蝕而產(chǎn)生的鐵
? 檢測礦物質和礦物鹽/酸性污染物
? 檢測鈉，通常來自冷卻系統(tǒng)泄漏，這可能會迅速損壞設備
? 識別可能將污染物引入工藝的泄漏
? 檢測鍋爐蒸汽中攜帶的化合物
Cation resin columns can be helpful in several applications, including:
? Spotting iron which is due to corrosion of the power plant
? Detecting minerals and mineral salts/acid contaminants
? Detecting sodium, typically from cooling system leaks which can damage equipment quickly
? Identifying leaks that can introduce contaminants to the process
? Detecting compounds carried over in the steam from the boiler
公用事業(yè)工廠在陽離子電導率方面經(jīng)常面臨哪些挑戰(zhàn)？
What challenges do utility plants often face with cation conductivity?
有時工廠會使用設計不良或尺寸過大的陽離子交換筒，誤以為這樣可以延長使用壽命。然而，這可能會導致交換率不理想、樹脂動力學不佳、浸出并導致測量不準確。
除了使用正確的離子交換柱、優(yōu)質樹脂以及在耗盡時更換或再生樹脂外，樣品溫度也會對陽離子電導率測量產(chǎn)生不利影響。
例如，電導率對溫度高度敏感，因此樣品溫度不能太高。通過使用高質量樹脂、定期維護以及仔細控制樣品流量和溫度可以防止這些問題。不要僅僅依賴儀器的內(nèi)置溫度補償，而是在工程師的操作條件下對其進行驗證。
考慮使用二次取樣冷卻來消除溫度偏差并提高測量穩(wěn)定性。
Sometimes plants use poorly designed or oversized cation exchange cartridges with the misguided belief that they will extend service life. However, this can result in suboptimal exchange rates, poor resin kinetics, leaching and can lead to inaccurate measurements.
In addition to using the correct ion exchange column, good quality resin and replacing or regenerating the resin when exhausted, sample temperature can adversely affect cation conductivity measurements.
For example, conductivity is highly temperature-sensitive, so the sample temperature mustn’t be too hot. These issues are prevented by using high-quality resin, conducting regular maintenance, and carefully controlling the sample flow and temperature. Don’t just rely on an instrument’s built-in temperature compensation, validate it in your operating conditions.
Consider using secondary sample cooling to remove temperature bias and improve measurement stability.
公用事業(yè)工廠如何確保陽離子電導率計劃成功？
How can utility plants ensure a successful cation conductivity program?
確保用戶使用適當?shù)年栯x子樹脂柱尺寸來提供所需的運行時間，并且測量傳感器在與電導率傳感器兼容的流速下是準確的，通常約為每分鐘 100 到 200 cc。
此外，確保用戶了解 EPRI、IAPWS 和 ASTM 的最新指南和最佳實踐。如果需要，可以聘請專家合作伙伴來確保測量準確可靠。
將用戶的分析系統(tǒng)與 EPRI 和 IAPWS 指導進行基準測試，以確定工廠類型、化學和操作參數(shù)的最低核心儀器?？紤]使用智能化學警報增強系統(tǒng)，以提高對測量的信心。
Ensure you utilize the appropriate cation resin column size to deliver the runtime you require and that your measurement sensor is accurate at flow rates compatible with conductivity sensors, usually about 100 to 200 cc per minute.
Additionally, assure you are up-to-date on the latest guidelines and best practices from EPRI, IAPWS and ASTM. If needed, you can pull in an expert partner to ensure your measurements are accurate and dependable.
Benchmark your analytic system to EPRI and IAPWS guidance on minimum core instrumentation for your plant type, chemistry and operating parameters. Consider augmenting the system with Smart Chemistry Alarms for improved confidence in measurements.
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