(292d) Cyclones a la Zenz? | AIChE

(292d) Cyclones a la Zenz?


Knowlton, T. M. - Presenter, Particulate Solid Research, Inc.
Karri, R., Particulate Solid Research, Inc.
Dr. Fred Zenz was a one of the first people to chronicle flows in fluidized beds, risers, solids transport systems and cyclones in his famous pioneering Zenz/Othmer book “Fluidization and Fluid-Particle Systems:. Cyclones (which separate solids from an exit gas stream) are a necessary piece of equipment in nearly all fluidized-bed processes, and Fred was one of the first to develop a technique to predict cyclone efficiencies and cyclone pressure drops. The method that he developed is still in use today by many organizations and was widely publicized in the “Manual on Disposal of Refinery Wastes” in 1975.

The Zenz method of characterizing cyclone operation consists of taking the particle size distribution (PSD) in the carryover (entrained) solids from a fluidized bed and subdividing the PSD into several “cuts”. Each “cut” is then analyzed to determine if it can be collected by the cyclone relative to a collection model. The model is then used to calculate cyclone efficiency at extremely low loadings, and the effect of loading on cyclone efficiency is predicted.

Cyclone pressure drop is determined by summing several individual components of the pressure drop. A little-known aspect of cyclone pressure drop is that as solids loading increases from near zero loading, cyclone pressure drop initially decreases as solids loading is increased. The Zenz method cyclone analysis takes this unique characteristic of cyclones into account.

In this presentation, the Zenz method of cyclone analysis will be described in detail.