Rotary Valves in Pneumatic Conveying Systems

Rotary valves are used almost universally in pneumatic conveying systems. They serve three main functions: 1) to provide a pressure-seal (airlock) between two adjacent processes, 2) to provide solids metering (feeding) and 3) to provide a combination of solids metering and a pressure-seal for feeding solids into a pneumatic conveying system. Rotary valves are common devices for feeding solids into a pneumatic conveying pipeline, and they function in different ways in different circumstances. For instance, rotary valves can function as follows: • As an airlock at locations where an air-seal is needed, such as at the end of a pneumatic conveying system where the conveyed solids are discharged from a receiving vessel into a storage hopper, bin or silo • As a feeder when they are used to discharge a fixed or a variable volumetric flow of solids from an upstream process to a downstream process • As a combination airlock and a feeder when they meter solids into a pneumatic conveying pipeline Key aspects of how rotary valves are designed and used are discussed below. Types of rotary valves. Rotary valves are generally made in the following three varieties: 1. Drop-through type 2. Off-set or side-entry type 3. Blow-through…