(70cd) Guide to Handling Rotary Airlock Leakage in Pneumatic Conveying Systems

Pneumatic conveying systems utilize pressure differential created by a gas source to drive the transfer of material. Rotary airlock valves are the most common piece of equipment used to feed the material into or out of the air stream. The rotary airlock, however, is not a perfect sealing device and there is an inherent leak of the convey medium proportional to the pressure differential across the airlock. The leakage volume can create a number of process issues if not dealt with properly. Airlock leakage has been known to limit flow of material into airlocks, create major housekeeping or environmental issues and pressurize upstream equipment. There is no single equipment arrangement that will properly vent all applications. Rather the best solution is a function of the available equipment, material characteristics, and proper pipe selection. The intent of this paper is to analyze six industry methods for handling leakage, where each can fail a user and the applications that best suit the individual method.