What Are the Causes of the Fouling in Plate Heat Exchangers
The plate heat exchanger will produce dirt after long-term use. Because the dirt layer has a very low thermal conductivity, it will increase the heat transfer resistance and reduce the heat transfer efficiency of the heat exchange equipment; When there is a scaling layer on the surface of the heat exchange equipment, the flow area of the fluid channel in the heat exchange equipment will be reduced, resulting in increased resistance when the fluid flows through the equipment, and more pump power will be consumed, resulting in increased production costs. What are the causes of fouling in the heat exchanger?
I. solidified dirt:
Dirt formed by the solidification of fluid on the supercooled heat exchange surface. For example, when water is below the freezing point, it solidifies into ice on the heat exchange surface. The uniformity of temperature distribution has a great influence on this kind of dirt.
II. Biological dirt:
Except for seawater cooling devices, general biological dirt refers to microbial dirt. It may produce slime, which in turn provides conditions for the reproduction of biological dirt. This kind of dirt is very sensitive to temperature. Under appropriate temperature conditions, biological dirt can generate a considerable thickness of dirt layer.
III. crystalline dirt:
Deposits formed by the crystallization of inorganic salts dissolved in the fluid on the heat exchange surface usually occur during supersaturation or cooling. Typical dirt such as calcium carbonate, calcium sulfate and silica scaling layer on the cooling water side.
IV. corrosive dirt:
Fouling caused by corrosive fluid or corrosive impurities in the fluid corroding the heat exchange surface. Generally, the degree of corrosion depends on the composition of the fluid, the temperature and the pH value of the fluid being treated.
V. particle dirt:
Accumulation of solid particles suspended in the fluid on the heat exchange surface. This kind of fouling also includes the precipitation layer of larger solid particles on the horizontal heat exchange surface due to gravity, that is, the deposition of the so-called precipitated fouling and other colloidal particles.
VI. chemical reaction dirt:
The dirt produced by the 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 chemical reaction.