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Causes of scale formation in plate heat exchanger
Aug 11, 2020

Plate heat exchangers have more internal turbulence than other heat exchangers and have a strong self-cleaning capability, so they are less prone to scaling. However, scaling will inevitably occur after long-term use. In order not to affect the use, we need to know the cause of scaling and then solve the problem accordingly.


1. Granular dirt: the accumulation of solid particles suspended in the fluid on the heat exchange surface. Such dirt also includes the precipitation layer formed by the gravity effect of larger solid particles on the horizontal heat exchange surface, namely the deposition of dirt and other colloidal particles.


2, corrosive dirt: corrosive fluid or fluid containing corrosive impurities, corrosion on the surface of the plate heat exchanger caused by the dirt, usually, the degree of corrosion depends on the composition of the fluid, temperature and the pH value of the treated fluid.


3. Chemical reaction dirt: the dirt produced by chemical reaction 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. Solidified dirt: the dirt formed by fluid solidifying on the supercooled heat exchange surface, such as ice solidified on the heat exchange surface when water is below the freezing point. The uniformity of temperature distribution has a great influence on such dirt.


5. Crystalline dirt: The deposits formed by the crystallization of inorganic salts dissolved in fluids on the surface of plate heat exchangers usually occur during supersaturation or cooling. Typical dirt such as calcium carbonate, calcium sulfate and silica scaling layer on the cooling water side.


6. Biological fouling: Except for seawater cooling device, biological fouling generally refers to microbial fouling, which may produce slime, which in turn provides conditions for the reproduction of biological fouling. Such fouling is very sensitive to temperature, and under appropriate temperature conditions, biological fouling can generate appreciable thickness of fouling layer.

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