The plate heat exchanger is a heat exchanger which is formed by pressing a thin metal plate into a heat exchanger plate having a certain corrugated shape, and then stacking and fastening with a splint and a bolt. During the use of the plate heat exchanger, due to improper operation of the water treatment equipment, the water quality control is not strict, and the circulating water that does not meet the water quality standard is injected into the heat exchanger, and the calcium and magnesium carbonate in the water is decomposed into calcium carbonate and hydrogen magnesium oxide after being heated. Some of these precipitates are bonded to the heated surface of the heat exchanger with a large heat to form a hard scale; the other part is suspended in the circulating water and deposited on the heated surface with a lower flow rate to form a secondary scale. Because the thermal conductivity of scale is extremely poor (the thermal conductivity is only 1130-1150 of the thermal conductivity of steel), the heat transfer of the plate heat exchanger is deteriorated, the heat transfer efficiency is greatly reduced, and the thermal energy is seriously wasted. According to the data, the thermal efficiency is reduced by about 8% for every 1 mm of scale increase. The presence of scale can block the plate heat exchanger passage, increasing the resistance of the system, affecting the safety of the equipment and the normal operation of the thermal system.