Pour water into the cleaning tank of the shell and tube heat exchanger to check that the system cycle is normal, and then add an appropriate amount of cleaning agent to start the cycle cleaning. According to the chemical cleaning process, during the cycle, the concentration of the cleaning solution in the cleaning tank should be checked every 1h, so that the concentration of the cleaning solution is always maintained within the safe and effective range of 0.10-0.15mol/L, and the cleaning is added according to the measured data. Agent. Chemical cleaning without disassembly may take longer, and a combination of cyclic cleaning and overnight immersion cleaning can be used to clean. When the concentration of the cleaning agent does not change for 2 hours or the amount of change is very small, the cycle can be stopped.