Plate heat exchangers are ideal equipment for liquid-liquid and liquid-vapor heat exchange. It has the characteristics of high heat exchange efficiency, small heat loss, compact and lightweight structure, small footprint, wide application and long service life. There are many types of plate stainless steel heat exchangers, and each type of plate heat exchanger has its own adaptation range. For cold and ice storage in areas with small temperature differences at the end, shallow-dense corrugated, high-NTU plate heat exchangers should be used. Asymmetrical plate heat exchangers and air coolers should be used for centralized heating of combined heat and power. The energy-saving device (economizer) should use fully welded plate heat exchanger. At the same time, the type of plate heat exchanger should be selected according to the design pressure and design temperature. If the design temperature is greater than 350 ° C and the design pressure is greater than 4 MPa, a plate and shell heat exchanger should be selected.