The plate heat exchanger is a high-efficiency heat exchanger which is assembled from a series of metal sheets with a certain corrugated shape. A thin rectangular channel is formed between the various sheets, and heat is exchanged through the sheets.It has the characteristics of high heat exchange efficiency, small heat loss, compact and light structure, small floor space and long service life. In the case of the same pressure loss, the heat transfer coefficient is 3-5 higher than that of the tube heat exchanger, and the heat recovery rate can be as high as 90% or more.In order to ensure the service life of the plate heat exchanger, not only the correct use of the equipment, but also the correct shutdown. The plate heat exchanger must stop the pump and cut off the power before stopping. If a vent valve is installed in the line, it should be opened. When the plate heat exchanger is stopped, the heat medium inlet valve is slowly closed, the inlet valve of the cold medium is closed, and the outlet valves of the two media are finally closed.For mediums with high temperature and corrosive media, the plate heat exchanger should be shut down as much as possible to avoid scalding and corroding equipment when the equipment is opened.