Tower is a process equipment of cylindrical welding structure, which is composed of cylinder, head ( cover) support. It is a kind of non-standard equipment specially designed manufactured for some production process requirements. Tower is a vertical equipment for distillation, purification, absorption, distillation other chemical unit operations, widely used for mass transfer heat transfer between gas-liquid liquid-liquid phases. According to the structure of tower internals, the tower can be divided into plate tower packed tower. If the inside of the container only supports materials without chemical reaction other physical chemical processes, there is no facility only simple auxiliary structure, it is also called tank. Vessels are divided into vertical (axis vertical) horizontal (axis horizontal) according to the type. Most of the towers are pressure vessels. Equipment for gas liquid phase liquid liquid phase material transfer. According to the structure, it can be divided into plate tower packing tower. There are a certain number of trays in the tray tower, the gas contacts with the liquid layer on the tray in the form of bubble jet to transfer the substance. The packing tower is equipped with a certain height of packing, the liquid flows top to bottom along the packing, the gas contacts with the liquid membrane bottom to top to carry out material transfer. It is often used in distillation, water absorption, extraction other operations.