Modeling Concepts for Pulse Jet Filtration

Abstract

A new model is proposed for predicting system pressure loss for large, pulse jet filters. Key data inputs were derived from experiments involving single and three-bag systems filtering coal fly ash and talc with Dacron and wool felts. Pulse jet cleaning parameters, face velocity, and inlet concentration were the principal operating variables. Several techniques used in modeling reverse flow and mechanically shaken systems, such as the classical drag versus fabric loading relationships and dust dislodgement phenomena, have been applied successfully to pulse jet filtration. However, several new concepts are introduced to facilitate the physical description of the combined filtration and pulse jet cleaning processes. Highlighting the model design is the fact that steady state fabric dust loadings depend mainly on the adhesive force binding the dust layer to the fabric and the intensity of the cleaning pulse and not upon face velocity and inlet concentration. Additionally, the fabric dust loading is composed of two parts, a highly porous, “redeposited” phase and a freshly deposited layer whose K2 value is higher and readily predicted by filtration theory. The outgrowth of this study is a rational and relatively simple mathematical model whose output agrees well with test data from two independent sources.