A spectral approach of suspending solid particles in a turbulent stirred vessel

Abstract

The 2015 Grenville‐Mak‐Brown (GMB) correlation for predicting the just suspended condition assumes that the length scale of the suspending eddy is equivalent to the particle diameter. This article investigates the role of the time scale of the relevant eddies with respect to the particle response time. The local turbulence just above the tank bottom is gauged by means of single‐phase LESs at the just suspended conditions determined in new experiments in dilute suspensions. By means of a novel nondimensional Suspension number we found that the relevant suspending eddies in the inertial subrange are 1.2–1.5 times larger than the particle size while the required eddy time scale is of the order of two times the particle response time. Further, we concluded that the mean energy dissipation rate is a suitable approximation of the local energy responsible for suspension. These results do not impact the effectiveness of the GMB correlation.

Intensification of Solid–Liquid Suspension Performance in an Elliptical Uncovered Unbaffled Stirred Tank

“…There has already been some evidence to suggest that turbulence is the root cause of lifting force. , Further research also focused on the effects of turbulence detail on lifting force . For the just suspension process, the most important is not the macro turbulence but the local turbulence above the base . In addition, the eddies or vortexes at specific time scales are thought to be the direct cause of lifting force .…”

“…40 For the just suspension process, the most important is not the macro turbulence but the local turbulence above the base. 47 In addition, the eddies or vortexes at specific time scales are thought to be the direct cause of lifting force. 48 Consequently, it is now understood that vortex or eddy plays an important role in suspension and the primary issue of intensification in the suspension process is to generate more multi-scale (time scale and space scale) vortexes.…”

Numerical research on biomass wastewater treatment using double-partition vessel with off-centered impellers

“…Mechanically stirred vessels are widely used in the biological wastewater treatment process to perform several operations such as dissolution, crystallization, aerobic fermentation, hydrogenation, chlorination, organic oxidation, and chemical synthesis with suspended catalysts and/or suspension polymerization [2][3][4][5][6] . The treatment of complex multiphase components of biomass wastewater is usually performed using a multi-step method [1,[7][8][9] .…”