Tower is a process equipment with a cylindrical welded structure, consisting of a cylinder body, a head (or cap), and a support. It is a non-standard equipment designed and manufactured specifically for a certain production process requirement. A tower is an upright equipment used for distillation, purification, absorption, distillation and other chemical unit operations, widely used for mass and heat transfer between gas-liquid and liquid-liquid phases. According to the internal structure classification, towers can be divided into plate towers and packed towers. If the interior of a container only contains materials without undergoing chemical reactions or other physical or chemical processes, and there are no facilities or only simple auxiliary structures, it is also called a tank. Containers are classified into two types based on their type: vertical (with a vertical axis) and horizontal (with a horizontal axis). Most towers belong to pressure vessels. Equipment for transferring substances between gas and liquid phases or between liquid and liquid phases. Divided into two categories based on structure: plate towers and packed towers. There are a certain number of trays in the plate tower, and gas is transferred to the liquid layer on the trays in the form of bubbles or jets. There is a certain height of packing inside the packed tower, and the liquid flows down along the packing from top to bottom, while the gas contacts the liquid film in reverse flow from bottom to top for material transfer. Commonly used in distillation, water absorption, extraction and other operations.