During daily operation, loose mud, sand, and algae impurities adhering to the gaps between the plates of the plate heat exchanger should be periodically backwashed for preventive maintenance before forming hard scaling, in order to reduce the formation of fouling and blockage, resulting in a decrease in flow rate and a decrease in scaling rate. Taking the distilled water plate heat exchanger of a certain seawater desalination plant as an example, the online backwashing operation steps are as follows.
1) Close the inlet and outlet valves on the seawater side of the plate heat exchanger.
2) Disassemble the seawater inlet filter cartridge of the plate heat exchanger.
3) Connect the seawater inlet side drainage pipe to the plate replacement pressure plate filter cartridge flange and connect the external discharge pipeline.
4) Open the seawater outlet valve and backwash the plate. Precautions for online backwashing: Avoid overpressure backwashing and prevent the sealing gasket from being flushed out of the sealing groove; Repeatedly rinse multiple times; Check if the filter cartridge is damaged and replace it promptly.
Different methods can be used according to different situations. If the plate heat exchanger does not leak but the heat transfer efficiency decreases, offline cleaning can be chosen, preferably once a year. If there is leakage or offline cleaning is ineffective, the cleaning plate needs to be disassembled.
