Study on the homogenization speed in a tank equipped with maxblend impeller.

摘要

The goal of this work is to characterize experimentally the performance of a Maxblend impeller for solid suspensions.;Significant efforts have been devoted to better understand the solid liquid mixing phenomena, because of the large number of industrial applications of this operation. The major objective of solid-liquid mixing is to first create and then maintain homogenous slurry conditions. Such operations are commonly carried out in tanks stirred by suitable mechanical agitators. The important point in designing a solid-liquid suspension is choosing a high performance impeller for achieving both the dispersion of the particles and their suspension, at the same time.;The Maxblend impeller is one of the most efficient kinds of the new generation impellers. It is composed of a large bottom paddle and an upper grid. The paddle acts as a pump and the grid provides dispersion capabilities. The Maxblend impeller represents an interesting alternative to close clearance impellers and it has been used in many different processes ranging from gas dispersion to polymerizations.;In this study, an experimental investigation is carried out to characterize the mixing performance, for Newtonian fluids in a cylindrical tank equipped with a Maxblend impeller.;The homogenization speed (NH) is introduced as the critical speed for the uniform suspension and it is measured by Electrical Resistance Tomography. The experimental work consisted in obtaining the power consumption and the mixing time for various liquid viscosities in Maxblend. Also the effects of vessel geometry, off-bottom clearance and solid loading on solid suspension efficiency are investigated. According to the results, it can be confirmed that Maxblend is an interesting technology to obtain a uniform suspension in light of short mixing time and low power consumption. Key Words: Mixing, Suspension, Solid-Liquid, Maxblend, Newtonian, Viscous fluid, Homogeneous suspension.