Mixing Process in a Stirred Tank

Abstract

Beacon Diagnostics Pvt. Ltd is well equipped, independent manufacturing facility as per WHO guidelines & U.S.F.D.A regulations. Beacon is a Research & Development Oriented Company. Their R&D sections are doing continuous research in Diagnostic Products at Navsari, Gujarat, India. Beacon Diagnostics Pvt. Ltd has faced problems in dilute process of chemicals, the mixing of chemicals in dilute process does not result into the homogenous mixture. It also causes difference in pH values at various levels for same chemical mixture in tank. This dilute process is t ime consuming. This project intend to modify the agitator to make the mixture homogenous so that we can get equal pH value at all levels for sa me chemical mixture in Stirling tank. Homogeneous mixture and required pH value of mixture is achieved by modifying industrial agitator .In this project, we modified agitator by increasing Number of Impeller Blade, using of Agitator with different shapes of blades, changing position and orientation of agitator. Result shows that By changing position and orientation of agitator at bottom of stirred tank with 45 0 Angle homogeneous mixture with 7.1 pH value at upper side and bottom side of stirred tank is received. Time of dilute process is reduced to 30 minutes from 2 hour.

Liquid-Phase Mixing in Stirred Vessels: Turbulent Flow Regime

“…Sasakura et al 34 have extensively carried out experimentation with flat-blade impellers of a variety of impeller diameters, different numbers of blades, and blade widths. They have observed that as the number of blades is increased the power number of the impeller increases and the mixing time decreases.…”

“…Sasakura et al 34 measured mixing times for impeller diameters over a range D ) 0.08-0.24 m in a vessel diameter of 0.3 m and arrived at the relation of the form θ mix ∝ D -3 for flat, eight-bladed turbine agitators. This was the first study to indicate the inverse cubic dependence of θ mix on the impeller diameter.…”

“…Sasakura et al 34 have carried out extensive investigations regarding the effect of the measurement location on the mixing time in a vessel stirred by FBTs. They have measured mixing times based on the conductivity response at eight altogether different locations encompassing the region near the liquid surface, the region of vigorous mixing (below impeller), and the region near the vessel bottom.…”

“…Mq ) 1 -exp(-kqNt); kq ) 0.418 for FBT, kq ) 0.295 for PBT Ogawa et al 35 model based on circulation of the fluid through a number of backmixed cells in series (Nθmix -2 -0.518NθC -2 ) 0.5 ) 5(T/D) 1.5 (NθCNP) -0.5 Sasakura et al 34 network of well-mixed zones exchanging flows; mass balance for solute written for each zone a small portion of the tank is well mixed; fluid circulates between the bulk and the well-mixed zone; the model is similar to that of Norwood and Metzner 10…”

Oscillating grid turbulence and bulk mixing at high schmidt numbers

“…Reynolds number and mixing time including two parameters depending on the geometrical characteristics of the mixing vessel, the agitator type and the Reynolds number region. A relation connecting mixing time, circulation time of newtonian liquids and power number in a mixing vessel, was presented by Sasakura et al (1980). For the mixing time measurement, a conductivity technique was applied.…”