Discussion on the anti-corrosion of heat exchange equipment
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Corrosion protection of heat exchange equipment is very important in chemical production, especially for those used with circulating water. Are there any other methods besides improving water quality? Are there heat exchangers equipped with magnesium rods for electrochemical corrosion protection? (Magnesium rods are included in household water heaters.)
Heat exchangers are exposed to almost all types of corrosion encountered in the petroleum and chemical industries, and such corrosion is usually hidden, making it difficult to detect. Once internal leakage is detected in the equipment, the corrosion is already quite severe. Moreover, in general, managers do not pay enough attention to the timely updating of stationary equipment. Additionally, heat exchangers account for a large proportion of investments, and the costs associated with their replacement are high, making it difficult to carry out replacements in a timely manner. There are many factors that cause corrosion in heat exchangers, and it is somewhat difficult to carry out effective anti-corrosion measures for them. In my opinion, the main aspects are as follows: 1. Strengthen anti-corrosion measures in terms of manufacturing processes, such as improving desulfurization and dechlorination processes ； 2. Identify the type of corrosion and upgrade the material of the tube bundle accordingly ； 3. Strengthen the anti-corrosion management of coatings ； 4. For circulating water coolers, it is necessary to improve the management of the quality of the circulating water, such as reducing the amount of silt in it ； 5. For circulating water coolers, it is necessary to increase the flow rate of the circulating water in order to prevent scaling due to too low flow rates, which could lead to corrosion beneath the scale ； 6. For tube bundles that have been in use for a long time or have a history of blockages, it is advisable to update them promptly.
Circulating water heat exchangers are generally made of carbon steel, with the inner surface coated to prevent corrosion; copper tubes are also used for the heat exchange tubes. Installing active metals such as magnesium rods is a common anti-corrosion measure. Metals like magnesium rods are more reactive than carbon steel, and they corrode first in corrosive environments, thereby protecting the carbon steel equipment. This method is commonly known as cathodic protection using sacrificial anodes.
Thank you, I finally understand. But I haven’t seen such equipment in my own factory yet. Could you give an example of a situation where it’s necessary to use this method for corrosion protection?