Plate columns and packed columns
Plate columns and packed columns are one of the most important unit in chemical production  equipment. Tower equipment is by its internal structure to gas (steam) or liquid-liquid two-phase liquid between the full access to the mass transfer and heat transfer. Equipment to complete the tower by a distillation unit operations, absorption, desorption, extraction, washing, cooling and gas humidification and so on.

Classification of towers based on internal structure：plate column and packed column and so on. There are a certain number of trays in plate column。Gas is into the tower from the bottom of the tower, rising gas and falling liquid mass on each tray. Be with a certain degree of filler layer in packed column, for example，the higher the required height of the fill, filler can be divided into paragraphs. Membrane downward along the surface of the liquid flow of filler, filler gas mass transfer from the bottom up through the liquid membrane layer。 Tower packing is divided into two categories: random packing and structured packing. Random packing’s materials are metal, plastic and ceramics; structured packing’s materials are sheet metal or wire, and plastic mesh.