Clean the dirt or plate scale in the flow channel of the heat exchanger. For the new operating system, clean it once a week according to the actual situation. When cleaning the scale on the surface of the plate (mainly refers to CaCO3), choose 0.3 sulfamic acid solution or 0.8 nitric acid solution containing 0.3 ulotropin, 0.2 aniline, 0.1 potassium thiocyanate as the cleaning solution, the cleaning temperature is 4O ~ 6O℃. When the equipment is not disassembled for chemical soaking and cleaning, it is necessary to open the heat exchanger cold medium inlet and outlet, or install DN25 cleaning port on the medium inlet and outlet pipe when installing the equipment. The mixed cleaning liquid is injected into the equipment, and the residual acid solution is cleaned with clean water after soaking to make pH≥7. When disassembling and cleaning, soak the plate in the cleaning solution for 30 min, then gently brush the scale with a soft brush, and finally clean it with clean water. Avoid damaging the plate and rubber pad during cleaning. If the method of mechanical backwashing without disassembly is adopted, a pipe opening should be connected on the medium inlet and outlet pipeline in advance, the equipment should be connected to the mechanical cleaning vehicle, the cleaning fluid should be injected into the equipment in the opposite direction of the medium flow, the cycle cleaning time should be 10 ~ 15 min, and the medium flow rate should be controlled at 0.05 ~ 0.15 m/s. Finally, clean water is used for several times to control the Cl concentration below