Keeping the plates of the plate heat exchanger clean is one of the important conditions for maintaining a high heat transfer coefficient. Between the plates, the medium moves along narrow and tortuous flow channels. Even if a very thin layer of scale is produced, it may cause changes in the flow path, affect the movement of the fluid, increase the pressure drop, and decrease the heat transfer coefficient.

    The following Propellent  details how to clean the plate heat exchanger:
    1. Chemical cleaning method
    Chemical cleaning is to circulate the chemical cleaning liquid through the heat exchanger, and chemically react with the dirt, so that the dirt and other deposits on the surface of the plate are dissolved and peeled off. This method does not need to disassemble the heat exchanger, which not only simplifies the cleaning process, but also reduces the labor intensity of cleaning. Because the plate corrugation can promote the violent turbulence of the cleaning liquid, which is conducive to the dissolution of the scale layer, the chemical cleaning method is an ideal method. 

    1) Commonly used chemical cleaning agents

    ●Cleaning agents that use dissolution to decontaminate(including water and organic solvents);
    ●Surfactant cleaning agents that use surface activity to decontaminate (such as cationic, anionic, nonionic and zwitterionic surfactants);
    ●Chemical cleaning agents that use chemical reactions to decontaminate (such as acids, alkalis, salts, oxidants, etc.).

     2) Common methods of chemical cleaning

    ●Circulation method: Use a pump to force the cleaning fluid to circulate for cleaning.
    ●Dipping method: Fill the equipment with cleaning fluid and let it stand for a certain period of time.
    ●Surge method: Fill the equipment with cleaning liquid, discharge part of the cleaning liquid from the bottom at regular intervals, and then load the discharged liquid back into the equipment to achieve the purpose of stirring and cleaning.


    2. Mechanical (Physical) cleaning method
    Physical cleaning is to use various mechanical external forces and energy to clean the dirt on the surface of the plate or pipeline.For example, the plate is manually washed with a brush to achieve the cleaning effect.
    The physical cleaning method is relatively direct, non-corrosive and reliable. Howeverer,regarding the thick and hard scale layer,it is not easy to clean. And there will be"dead spots" when cleaning the inside of complex structure.

    3. Comprehensive cleaning method
    For hard and thick  dirt layers ,it is difficult to clean them using only one of the above methods.In order to keep the plate clean,the comprehensive method is to first use chemical cleaning to soften the scale layers, and then use mechanical (physical) cleaning to remove them.