The plate heat exchanger is a high-efficiency heat exchanger which is assembled by stacking a series of metal plates with a certain corrugated shape. A thin rectangular channel is formed between the various sheets, and heat is exchanged through the plates. Plate heat exchangers are ideal equipmentfor heat exchange between liquid-liquid and liquid-vapor. It has the characteristics of high heat exchange efficiency, small heat loss, compact and light structure, small floor space, wide application and long service life. In the case of the same pressure loss, the heat transfer coefficient is 3-5 times higher than tube heat exchanger, and the floor space is one-third of the tube heat exchanger, and the heat recovery rate can be as high as 90% or more. There are two types of plate heat exchanger(frame type and brazed type). The plate form mainly consists of herringbone corrugated board, horizontal straight corrugated board and nodular plate.