A heat exchanger is a device that transfers a portion of the heat from a hot fluid to a cold fluid. Heat exchangers are commonly used equipment in chemical, petroleum, power, food, and many other industrial sectors, and play an important role in production. Heat exchangers can be used as heaters, coolers, condensers, evaporators, and reboilers in chemical production, and are more widely applied. There are many types of heat exchangers, but according to the principles and methods of heat exchange between cold and hot fluids, they can be basically divided into three categories: partition type, hybrid type, and thermal storage type. Most heat exchangers are used in high temperature and corrosive environments (with high or low pH), where corrosion structures are very severe. The utilization rate of heat exchange equipment directly affects the efficiency and cost of refining processes.

Corrosion is a very important cause of damage to heat exchangers.

The corrosion of heat exchangers mainly refers to the corrosion of plates. Uniform corrosion and localized corrosion are the two main types of corrosion of stainless steel plates in plate heat exchangers. Impurities, salts, gases, and microorganisms in the heat exchanger medium can cause corrosion to the tube plate and weld seam. Research has shown that industrial water, whether freshwater or seawater, contains various ions and dissolved oxygen, among which the concentration changes of chloride ions and oxygen play an important role in the corrosion shape of metals. In addition, the complexity of the metal structure can also affect the corrosion morphology. Corrosion that is concentrated on individual small points on the metal surface and has a greater depth is called pitting corrosion, also known as small hole corrosion or pitting corrosion. Severe crevice corrosion occurs in the gaps and covered areas of metal surfaces. Therefore, the corrosion of the welds between the tube plate and the column tube is mainly caused by pitting corrosion and crevice corrosion. From the outside, there will be many corrosion products and deposits on the surface of the tube plate, distributed with bubbles of varying sizes. When using seawater as a medium, galvanic corrosion can also occur.

Stress corrosion of heat exchangers requires a specific corrosive environment and sufficient tensile stress. Electrochemical corrosion, heat exchanger, and heat exchanger electrochemical corrosion are the most widespread types of metal corrosion. When the metal inside the cooling water system is exposed to aqueous solution or humid atmosphere for a long time, a micro battery, also known as a corrosion battery, will form on the metal surface. Oxidation reaction occurs on the anode, causing dissolution and reduction reaction on the cathode. Causing continuous metal corrosion in the cooling water system, thereby threatening the safe operation of the system. Temperature has a significant impact on chemical corrosion in chemical corrosion, heat exchangers, and heat exchangers. Steel is not easily corroded in dry air, but it is prone to oxidation and the formation of oxide scales at high temperatures. Its carbides are prone to decarburization reactions, which reduce the surface strength and fatigue limit of steel.

Biological corrosion of heat exchangers is mainly caused by the contact of metal surfaces with circulating water and other media in the cooling water system, which can easily lead to biological corrosion. The reason for biological corrosion is that organisms feed on organic corrosion inhibitors, and their metabolism produces acids, which damage the metal's corrosion-resistant protective layer. Biological metabolism consumes oxygen, resulting in uneven oxygen concentration on the metal surface and causing oxygen concentration corrosion.

The heat exchanger uses ceramic anti-corrosion coating to reduce corrosion and extend its service life. Circulating cleaning can be used for heat exchanger cleaning, by pumping the cleaning solution into the circulating water system for circulation. This method has a better cleaning effect on the plates after scaling.