ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Analysis of mixing effect and power consumption of cone-bottom dual Rushton turbines stirred tank

Yong-Xin Dai, Zhao-Hui Wang, Yi-Wei Fan, and Zi-Qiang Cheng

Key Laboratory of Metallurgical Equipment and Control Technology of Ministry of Education, Wuhan University of Science and Technology, Wuhan, China

E-mail: zhwang@wust.edu.cn

Received: 26 August 2021  Accepted: 4 December 2021

Abstract:

At present, the research on stirred tanks in the chemical process has focused on the flat-bottom and dish-bottom stirred tanks, and there are few reports on the cone-bottom stirred tanks. Based on the flow pattern of the flow field in the tank, this paper analyzes the stirring effect and power consumption of the cone-bottom stirred tank with dual Rushton turbines. Computational fluid dynamics (CFD) software is used to simulate the flow field characteristics in the stirred tank. The effects of the cone-bottom height, the impeller spacing and the ratio of impeller diameter to tank diameter on the power consumption and the flow pattern of the flow field in the tank are analyzed. The results show that when the ratio of cone-bottom height to the inner diameter of the tank is less than 0.0147, there is dispersed flow in the stirred tank. The dispersed flow can improve the velocity distribution of the bottom fluid. Compared with parallel flow, the power consumption and effective mixing zone of dispersed flow are reduced by 1.5% and 2.6%. When the ratio of the impeller spacing to the inner diameter of the tank is less than 0.294, the mixed flow is in the stirred tank. The fluid turbulence between the connected flow blades is the strongest, and the power consumption is relatively small. The change of the ratio of impeller diameter to tank diameter has the greatest impact on the connected flow, and the parallel flow is the least. When the ratio of impeller diameter to tank diameter is 1:1.7, the power number is reduced by 22.8% and 44.6% compared to 1:2 and 1:2.3, respectively.

Keywords: Stirred tank; Power consumption; Computational fluid dynamics (CFD); Flow pattern; Taper

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-02010-1

Chemical Papers 76 (4) 2177–2191 (2022)