The plate heat exchanger is composed of a group of corrugated metal plates. There are four corner holes on the plate for the two liquids for heat transfer to alternately exchange heat through their respective channels. After a certain period of time, the plate heat exchanger will adhere to a layer of white scale on the inner and outer walls. The main cause of scale formation is due to the relatively low solubility of calcium and magnesium salts in water. The solubility of this salt decreases as the water temperature rises, and it becomes intolerable salt. This salt will have the following effects on the plate heat exchanger:
(1) The thermal conductivity of scale is very poor. It is 30-50 times smaller than the heat conductivity of steel. The presence of scale will make the heat transfer on the heated surface worse, so that the heat transfer surface cannot reach the ideal temperature drop. According to the introduction of relevant data, after experiments, if 1mm thick scale is generated, the plate heat exchanger will reduce its efficiency by about 10%.
(2) It is difficult to remove the scale attached to the heat transfer surface. The maintenance cost is increased, which not only consumes manpower and material resources, but also damages the heating surface and reduces the life of the plate heat exchanger.
(3) After the scale is generated, the cross section of the internal and external circulation of the heat transfer surface will be reduced. Increased circulation resistance of circulating water inside and outside the heat transfer surface. In severe cases, the flow cross-section is very small and even being completely blocked will prevent the plate heat exchanger from operating normally.