When it comes to radiators, it is necessary to mention plate-fin radiators.
Its appearance has raised the heat transfer efficiency of radiators to a new level.
At the same time, plate-fin radiators have the advantages of small size, light weight, and can handle more than two kinds of media.
At present, its application has been widely applied in petroleum, chemical, natural gas processing and other industries. It is usually composed of baffles, fins, seals and deflectors, of which the plate bundle is an important part. Such a seemingly lightweight machine also needs to be carefully maintained to prevent it from being corroded by other substances. So let's analyze how to protect the radiator from corrosion?
1. To reduce the corrosivity of the medium, stress corrosion can be controlled by removing dissolved oxygen and oxidant in the medium, reducing the mass concentration of Cl - in the medium, and strictly controlling the mass concentration of sulfur in the medium is also an effective measure to control stress corrosion. The service life of plate heat exchanger can be extended by grasping the corrosion of plate heat exchanger medium to plate heat exchanger.
2. Improve the structure of plate-fin radiator. In order to avoid the retention of residual liquid and sediment, double-sided butt welding and continuous welding shall be used as far as possible during welding to avoid overlap welding and spot welding. The welding wire shall be filled in the welding process to ensure good weld formation.
3. Reduce residual stress. According to practical experience, the stress that causes stress corrosion cracking of plate heat exchanger is mainly residual stress, and the residual stress is mainly composed of internal stress caused by cold working and welding.
Heat treatment of cold-worked parts and welded parts is helpful to eliminate residual stress, thus also helping to prevent stress corrosion.
Stress annealing heat treatment or other methods of relieving residual stress are often used, such as hydrostatic test, vibration aging and hammering.
4. In electrochemical protection method, stress corrosion cracking is an anodic dissolution process under stress. Therefore, it can be controlled by electrochemical protection. The electrochemical protection method can not only prevent the stress corrosion cracking of the plate heat exchanger, but also stop the expansion of the plate heat exchanger even if the cracks occur under the condition of proper selection of protection parameters. Sacrificial anode protection or surface spraying of corrosion-resistant metal can be used.
5. The corrosion inhibitor is added to prevent the stress corrosion cracking of corrosion stainless steel from occurring in the activation potential zone. It must be covered with adsorption corrosion inhibitor. A dense adsorption film is formed on the metal surface, which inhibits the metal corrosion process. In this way, the surface of the plate heat exchanger is protected from corrosion.