According to the mechanism of fouling layer deposition, the plate type heat exchanger scale can be divided into granular dirt, crystal fouling, chemical reaction fouling, corrosive dirt, biofouling.
(1)Particulate soil: The accumulation of solid particles suspended in a fluid on a heat exchange surface. Such fouling also includes the deposition of larger solid particles on the horizontal heat transfer surface by gravity, the so-called deposition of fouling and other colloidal particles.
(2)Crystalline fouling: A deposit formed by the crystallization of an inorganic salt dissolved in a fluid on a heat exchange surface, usually occurring during supersaturation or cooling. Typical soils are calcium carbonate, calcium sulfate and silica fouling layers on the cooling water side.
(3)Chemical reaction fouling: The dirt generated by the chemical reaction carried out on the heat transfer surface, the heat transfer surface material does not participate in the reaction, but can be used as a catalyst for the chemical reaction.
(4)Corrosive soil: Corrosive fluid or fluid containing corrosive impurities that corrode the heat exchange surface. Generally, the degree of corrosion depends on the composition of the fluid, the temperature, and the pH of the fluid being treated.
(5)Biofouling: In addition to seawater cooling devices, general biofouling refers to microbial fouling. It may produce slime, which in turn provides conditions for the propagation of biofouling; this stain is sensitive to temperature, and at the appropriate temperature conditions, biofouling can produce a layer of dirt of considerable thickness.
(6)Solidified dirt: The dirt formed by the solidification of the fluid on the supercooled heat exchange surface. For example, when the water is below the freezing point, it solidifies into ice on the heat exchange surface. The uniformity of the temperature distribution has a great influence on this type of fouling.