Types of fouling in heat exchangers
For the commonly used heat exchangers, generally the fouling is classified into the following categories according to the fouling mechanism.
(1) Crystallized fouling: refers to the inorganic salt dissolved in the supersaturated flowing liquid and deposited on the surface of the heat exchanger, which is called crystallization fouling. Scale is the most common scale in industrial equipment. In water-cooled systems, due to supersaturated calcium in water, magnesium salts are crystallized from water in the surface of the heat exchanger due to changes in temperature, pH etc., and scale is formed
(2) Particulate soil: solid particles suspended in a fluid system such as sand, dust, carbon black, and dirt formed on the heat transfer surface.
(3) Chemical reaction fouling: formation of deposits between the heated surface and the fluid due to auto-oxidation and polymerization chemical reactions
(4) Corrosive type fouling: The heat exchange surface is corroded due to corrosive or corrosive impurities, and corrosion products are deposited on the heat exchange surface to form dirt.
(5) Bio-type soil: It is a kind of sticky deposit formed by the microbial population and its excreta and chemical pollutants, mud and other components adhering to the wall of heat exchange tubes, pipes.It called bio-type fouling.
(6) Solidified soil: On the super-cooled heat transfer surface, the cleaned liquid or the highly dissolved components of the multi-component solution are solidified and deposited to form fouling.