Corrosion and scaling of the circulating water in the constant and reduced pressure fifth-line cooler in petrochemical industries
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The image below shows the tube bundle of the water-cooled cooler on the fifth stage of the atmospheric and vacuum distillation tower in petrochemical industries. Model is FA600-113-25-2, with the tube bundle made of 10# steel. The operating condition is that the tube side uses circulating water, while the shell side uses reduced five-line flow ； Operating temperature: 30 degrees for the tube side and 167 degrees for the shell side ； The pressure in the tube side is 0.6 MPa, and that in the shell side is 0.59 MPa. This tube bundle has been in use for over 2 years, and a large amount of scale has accumulated on the circulating water side, along with corrosion, which affects the cooling performance of the water cooler.
In the petrochemical industry, water coolers using circulating water are prone to scaling and corrosion problems. This is because the circulating water contains various minerals and impurities, such as calcium and magnesium ions; these substances tend to undergo chemical reactions with the pipe walls at high temperatures, resulting in scale formation. Scale not only reduces heat exchange efficiency but can also cause pipe blockages and corrosion. Corrosion mainly occurs as a result of oxygen and other corrosive substances such as chloride ions in the circulating water acting on the steel. To prevent this, chemical agents can be used for regular cleaning, while water quality should be monitored to control the pH level and the concentration of corrosive substances in the circulating water, with appropriate addition of corrosion inhibitors. .