During the daily operation of the plate heat exchanger, scaling, corrosion and biological slime often occur in its circulating water system. As a result, the heat exchange efficiency of the plate heat exchanger is reduced, the circulating water flow rate and the pressure drop are increased. The reasons for the failure of the plate heat exchanger in the heating system are as follows:
(1) In the secondary network system of the heating system, the water used for the plate heat exchanger is generally untreated tap water containing a large amount of scale ions such as Ca2 + and Mg2 +. In the actual production process, the method of adding anticorrosive and scale inhibitors is often used to reduce the hardness of tap water. However, due to inadequate equipment and operation management, the addition of anti-corrosion and scale inhibitors cannot meet the requirements, which causes a large amount of Ca2 + and Mg2 + to saturate from the water and deposit on the metal surfaces in the heat exchanger and the pipe network to form scale.
(2) After the sediment and various bacteria and algae in the water enter the circulating water system. The temperature is suitable for the growth and reproduction of microorganisms, and a large amount of microbial slime is generated in the system, which is attached to the heat exchanger and mixed with scale to form biological dirt.
(3) Dissolved oxygen and salt in water will cause oxygen corrosion and chemical corrosion to the metal material of the heating system.Because the heating system is composed of a variety of metal materials. In water containing a large amount of electrolyte salts, galvanic couples and corroded batteries are formed between different metals, thereby causing electrochemical corrosion of heating system metals.