Using supplementary air in dense-phase pneumatic conveying
In past columns, we've discussed pneumatic conveying topics including system design, operation, equipment, and applications. Many of the columns have concentrated on one area of a pneumatic conveying system, such as the air (or other gas) mover, material supply vessel, material feeder (line charger), conveying line, or air-material receiver (or receiving bin). In this column, we'll focus on a topic related to the conveying line: introducing supplementary air to help aerate the conveyed material and prevent line plugs in dense-phase conveying systems.
Let's start by reviewing some dense-phase basics. Unlike in a dilute-phase system, in which the material is conveyed in suspension throughout the conveying line, in a dense-phase system the material is not conveyed in suspension and usually moves at a much lower velocity than in a dilute-phase system. The dense-phase system, in which the material-to-air ratio can be quite high, can be one of two basic types: