Date of Award

5-31-1993

Document Type

Thesis

Degree Name

Master of Science in Environmental Engineering - (M.S.)

Department

Civil and Environmental Engineering

First Advisor

Piero M. Armenante

Second Advisor

Angelo J. Perna

Third Advisor

Paul N. Cheremisinoff

Abstract

A significant amount of data can be found in the literature on power consumption of single-impeller agitation systems. However, little and incomplete information is available for power consumption in multiple-impeller systems. Therefore, the main objective of this study is to experimentally determine the power consumed by multiple impellers in mixing vessels as a function of impeller type, impeller off-bottom clearance, impeller spacing, and agitation speed.

In this work, the power dissipated by combinations of one, two or three impellers of either identical types or different types was studied. The power drawn by each individual impeller was measured by means of strain gages. The results indicate that the power consumed by each impeller is strongly dependent on the combination of impeller types, spacing, clearance, and the presence of other impellers. For triple-disc turbine systems, the maximum power consumption was found when the intermediate impeller was spaced midway between the other two. In addition, the total power drawn was approximately equal to the sum of each individual power drawn when the spacing was about twice the impeller diameter.

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