How can cooling towers prevent corrosion and scaling of metal components when operating in high-humidity or high-salt-spray environments?
Publish Time: 2025-12-09
In high-humidity or high-salt-spray environments, cooling towers, as heat exchange equipment exposed to harsh climates for extended periods, face severe corrosion challenges. Moisture and chlorides in the air not only accelerate steel oxidation but can also form difficult-to-remove deposits on heat exchange surfaces, reducing heat transfer efficiency, clogging water flow channels, and even causing a decrease in structural strength. Therefore, effectively preventing corrosion and scaling of metal components is crucial for ensuring the long-term stable operation of cooling towers in coastal, island, or chemical industrial areas.
Firstly, material selection is the first line of defense against corrosion. For high-humidity and high-salt environments, key metal components of cooling towers—such as the tower frame, fan support, water collection tray, and fasteners—are typically made of materials with stronger corrosion resistance. For example, hot-dip galvanized steel provides good initial protection by using a zinc sacrificial anode to protect the base steel. Under more demanding conditions, stainless steel (such as 304 or 316L) is commonly used, as its chromium, nickel, molybdenum, and other alloying elements form a dense passivation film on the surface, effectively blocking chloride ion corrosion. Some high-end designs even use fiberglass reinforced plastic (FRP) or composite materials to replace metal structures, fundamentally avoiding the risk of electrochemical corrosion.
Secondly, surface protective coating systems further enhance durability. Even when using galvanized or stainless steel materials, localized corrosion risks remain at welds, cuts, or mechanical damage. Therefore, high-performance anti-corrosion coatings are often applied to metal surfaces, such as epoxy zinc-rich primer combined with polyurethane topcoat, forming a multi-layered barrier. These coatings not only have excellent adhesion and impermeability but also resist UV aging and salt spray corrosion. For parts such as packing support beams that are in long-term contact with circulating water, rubber linings or sprayed wear-resistant and anti-corrosion layers are used, combining erosion resistance and rust prevention.
Furthermore, water quality management is crucial for inhibiting scaling and microbial corrosion. In high-humidity, high-salinity areas, the water source itself often has a high salt content. Combined with the continuous deposition of salt from the air, this easily leads to the precipitation of calcium carbonate, calcium sulfate, or chloride crystals on heat exchange surfaces, forming scale. Simultaneously, the warm, humid environment promotes the growth of algae and bacteria (such as sulfate-reducing bacteria), whose metabolic products accelerate pitting and crevice corrosion. Therefore, a comprehensive water treatment system is essential: softening and filtering to remove hardness ions; adding corrosion and scale inhibitors to form a protective film; and regularly sterilizing and killing algae to control biofilm growth. Furthermore, properly controlling the concentration ratio and timely wastewater discharge can effectively slow down the scaling process.
In addition, structural design details are crucial. A good drainage slope prevents water stagnation and reduces localized corrosion; direct contact between dissimilar metals prevents galvanic corrosion; all connections should use sealant or anti-corrosion gaskets to prevent salt spray intrusion into gaps. If the fan blades are made of metal, special treatment is required, or engineering plastics should be used to completely avoid corrosion problems.
Finally, regular maintenance and monitoring are the guarantee of long-term protection. Even with adequate initial protection, coatings will still age over long-term operation, and water quality may fluctuate. Therefore, a regular inspection system is necessary, focusing on vulnerable areas such as welds, bolts, and corners of the water pan; using corrosion strips or online monitoring probes to assess the actual corrosion rate; and promptly cleaning and reapplying protective coatings upon detecting early rust or scaling to prevent minor issues from escalating into structural damage.
In conclusion, corrosion and scaling prevention for cooling towers operating in high-humidity, high-salt-spray areas does not rely on a single method, but rather on a systemic engineering approach encompassing materials, coatings, water treatment, structure, and operation and maintenance. Only through a multi-layered, full-cycle protection strategy can cooling towers remain robust in harsh environments, continuously and efficiently fulfilling their heat exchange mission and providing reliable protection for industrial systems.
