Chemical Engineer - Cooling Water (2) What is the common problems of cooling water
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.
In general, there are three main problem associated with industrial cooling water, corrosion, scaling and bio-fouling .
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 .
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.
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 .
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.
.Chemical Engineering at the University of Florida" (PDF). www.che.ufl.edu. Retrieved 27 March 2018.
.Hemmasian-Ettefagh, Ali (2010). "Corrosion Inhibition of Carbon Steel in Cooling Water". Materials Performance. 49: 60–65.