Selecting Designing & Troubleshooting Feeders

Feeders are used to control the rate of material discharge from a bin, hopper, silo or bunker outlet. Unfortunately, the mechanisms governing operation of feeders under bin outlets are not well understood in the bulk solids handling industry. As a result, many existing screw and belt feeders, as well as a myriad of other types of feeders, do not operate properly. This often leads to excessive power consumption, abrasive wear, particle attrition and, even worse, unreliable material flow. This topic is important to industry because methods are available to minimize, if not eliminate, process irregularities caused by improper design of volumetric and gravimetric bulk solids feeders.

How to Prevent Particle Caking and Attrition of Bulk Solids

Powder caking, whether or raw material in bags or drums, or during storage of in-process material, is a major cause of problems. Being able to predict the conditions under which caking occurs, as well as identifying the material properties that lead to caking is necessary for avoiding or solving this problem. This session will discuss a novel approach that utilizes both micro and macro properties of powders to identify the causes of caking and develop solutions. Properties discussed will include particle surface composition and hardness, moisture sorption/desorption characteristics, particle strength and size distribution, a powder’s response to temperature and humidity cycling, and the change in shear strength as a function of time consolidation and environmental conditions.

Particle degradation, or attrition, can also be a major concern during the handling of friable bulk solids. Particle attrition can negatively impact product quality, performance, or induce bulk solids flow problems. Understanding the causes of particle attrition, as well as common solutions which can be employed to minimize, if not eliminate this problem, will be covered in this session