Heat exchangers are indispensable equipment for heat exchange and transfer in chemical production processes. In industrial production such as petroleum, chemical, light industry, pharmaceutical, energy etc., it is often used to heat a low temperature fluid or to cool a high temperature fluid, vaporize the liquid into steam or condense the steam into a liquid. The heat exchanger can be a unit of equipment such as heaters, coolers and condensers. Heat exchangers are important unit equipment in chemical production. According to statistics, the tonnage of heat exchangers accounts for about 20% of the entire process equipment and even up to 30%. With the rapid development of energy-saving technologies, there are more and more types of heat exchangers. It is suitable for heat exchangers with different media, different working conditions, different temperatures and different pressures. The structure type is also different. Heat exchangers can be classified according to heat transfer principle, use and structure. According to the heat transfer principle, it can be divided into surface heat exchanger, regenerative heat exchanger, fluid connection indirect heat exchanger and direct contact heat exchanger. According to the use, it can be divided into heater, preheater, superheater and evaporator. According to the structure of the heat exchanger, it can be divided into a floating head heat exchanger, a fixed tube plate heat exchanger, a U-shaped tube plate heat exchanger and plate heat exchanger.