In order to investigate the micro-mixing performance of centripetal turbine in a non-Newtonian fluid system, the parallel competitive reactions of phosphate/iodide/iodate were used to measure the segregation index in a 0.282 m diameter cylindrical oval-bottom baffled stirred tank. The micro-mixing performance was compared among standard six straight blade turbine (DT), down-pumping pitched blade turbine (PBTD), centripetal turbine (CT), and ten dual-impeller combinations. The power numbers of single impellers were measured experimentally. And the influences of injection time, power consumption of unit volume, impeller type on the segregation index were investigated. The results showed that the power number remained constant with the increase of power, and the power number of DT was roughly twice that of CT and four times of PBTD. With the increase of feeding time, the segregation index decreased gradually to an asymptotic level. With the increase of power consumption per unit volume, the segregation index of the three propellers decreased gradually, and keeps the relative level of DT<CT<PBTD. For the dual-impellers systems, the product distribution was dominated by the upper impeller since the feeding location was at the liquid surface. It was found that the combination of PBTD and DT with both strong shear and intensive circulation was more advantageous among the dual-impeller systems. In the dual CTs with backswept installation of lower propeller enhanced the micro-mixing. Contrast between single and double impellers at the same power consumption per unit volume, most of dual-impeller systems can improve the micro-mixing due to complementary flow pattern.
Juan YANG Qinghua ZHANG Chao YANG Zaisha MAO
. Micro-mixing characteristics of non-Newtonian fluid in a stirred tank agitated with different impellers[J]. The Chinese Journal of Process Engineering, 2019
, 19(5)
: 865
-871
.
DOI: 10.12034/j.issn.1009-606X.219128
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