Chemical Engineer - Cooling Water (2) What is the common problems of cooling water
化工冷却水2--冷却水中常见的问题
Last post we discussed about what is cooling water, this post we will discuss the common cooling water problems and what is the possible solution for these problems.
上一个帖子我们讨论了什么是冷却水,这个帖子我们就简单介绍一下冷却水中的常见问题.
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In general, there are three main problem associated with industrial cooling water, corrosion, scaling and bio-fouling [1].
一般来说工业冷却水中几个主要常见的问题为金属腐蚀，矿物质结垢和生物沉积。
First, let us talk about CORROSION, corrosion normally happened on the Carbon Steel / yellow metal heat exchanger tubing; the reason for corrosion is the electrochemical reaction happened on the metal surface. Where the steel surface can divide into anode and cathode, on anode; the Fe release electrons to form Fe2+/3+; and on cathode, oxygen will reduce to O2-. There are a lot of types of corrosion, for example, general corrosion, pitting, under deposit corrosion and MIC (microbiological induced corrosion). While each mechanism can be talked a lot, the most hazard corrosion form is localized corrosion, which is difficult to detect and failure can occurred in a short time. The common way to mitigate corrosion would be change metallurgy and/use chemical inhibitor control [2].
首先我们可以探讨一下腐蚀，腐蚀通常是在碳钢和铜合金的热交换管上发生的。腐蚀发生的主要原因是电化学法使金属表面的电化学反应。反应的时候进入本面会分成阴极和阳极阳极中铁会释放电子变成铁离子，阴极上氧气会被氧化成氧离子。腐蚀有很多的种类，比如说平均腐蚀，点蚀，沉积下腐蚀还有生物腐蚀。这里的每一种分类都可以讨论很多，不过总的来说危害最大的腐蚀是局部腐蚀。这种腐蚀很难检测并且很容易在短时间内形成失效。常见的应对方法是升级金属材料或者使用化学缓蚀剂。
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SCALING, is another big issue for the cooling water. Like the CaCO3 formed during the water boiling process; some scale will precipitated when the temperature of water rise up. When scaling building up, it not only decrease the heat transfer performance for the heat exchanger but also increase the operation pressure. For cooling water, it will be worse since a lot of water will evaporated in the cooling tower case the cooling water concentration increase. The common way of scaling control would be soften the source water and using scaling inhibitors.
结垢，是工业冷却水中的又一大问题。比如碳酸钙这样的结构就会在生活中烧水的过程中产生水垢，许多的矿物质会在温度升高的时候沉积出来。一旦积垢增加，不仅会减少热传递并且有可能会增加过程压力。对于冷却水来说这一过程会被加速因为许多水会被蒸发来释放热量。常见的处理方法有软化水源还有使用阻垢剂。
BIO-FOULING, when we introduce the river water to the engineer process, we invite the microbiological friends coming in the process as well. These living creatures can stay and grow in the warm and nutritive cooling water environment to form bio-films. Similar as scaling, this will effect the heat transfer coefficient as well as increase the operation pressure. Moreover, the bio-film can form MIC dur to certain types of bacteria. The common way to control bio-fouling is using biocide just like the swimming pool. But the type and dosage for biocide need to be carefully designed [3].
生物沉积，当我们吸入河水的时候我们也把河水中别的小朋友都带了进来。这些小生物会在冷却水中的温暖和有营养的环境里快乐的生长，并产生生物膜。就和结垢一样，这些生物膜会影响热传递并且会增加过程压力；另外，这些生物膜还可能会导致生物腐蚀。通常的控制办法是使用杀菌剂，就像我们处理游泳池的水一样。但是化工过程中的杀菌剂的种类和剂量都要严格控制。
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This chapter we talked about the common problems that happened in the cooling water and some common treatment methods. While each one of them can be talked into much more detail which will be happened in the following sections. Stay tuned and happy steemit.
本章我们主要讲述了一下工业冷却水的常见问题和处理方法，其实其中的每一个问题都可以在细节上有许多的讨论，在以后的章节之后我们可能会介绍。祝大家开心steemit。
Reference,
[1].Chemical Engineering at the University of Florida" (PDF). www.che.ufl.edu. Retrieved 27 March 2018.
[2].Hemmasian-Ettefagh, Ali (2010). "Corrosion Inhibition of Carbon Steel in Cooling Water". Materials Performance. 49: 60–65.
[3]. https://www.watertechonline.com/wastewater/article/15550672/biofouling-prevention-in-industrial-cooling-water-systems
