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Compared to plate heat exchangers, plate-and-shell heat exchangers use a plate bundle instead of individual plates; this plate bundle is typically formed by welding plates together, either using laser welding or plasma welding. Because it has high technical requirements for laser welding. There is an external pressure vessel shell, known as the casing. The shell withstands the pressure of the fluid medium. The plate bundle is formed by welding together multiple plates, whose flow channels are shaped like herringbone waves; adjacent plates are inverted with respect to each other, which improves heat exchange efficiency and increases turbulence, thereby preventing the formation of fouling on the plate surfaces. The heat transfer plate bundle and the shell constitute the most basic structure of a plate-and-shell heat exchanger; therefore, it inherits the advantages of plate heat exchangers, namely high heat transfer efficiency and low floor space requirement. At the same time, it inherits the advantages of shell-and-tube heat exchangers in terms of resistance to high temperatures and high pressures. The plate bundle is fixed to brackets inside the shell and connected via corrugated expansion joints and shell nozzles, allowing for easy removal of the plate bundle. Another feature of it is that it does not use adhesive strips, thus saving a lot of costs and offering high economic efficiency. Plate-shell heat exchangers are widely used in the petrochemical and natural gas industries, power plants, as well as industries such as food and pharmaceuticals.