Impeller high solidity

Axial flow deviees sueh as high-effieieney (HE) impellers and pitehed blade turbines give better performanee than eonventional pitehed blade turbines. They are best suited to provide the essential flow patterns in a tank that keep the solids suspended. High-effieieney impellers effeetively eonvert meehanieal energy to vertieal flow... 

Reeently, Corpstein et al. [43] found that high-effieieney impellers provide the same levels of solids suspension at redueed eapital and operating eosts. They introdueed the term just-suspended for the most eommonly eneountered level of liquid solid agitation. This oeeurs when none of the solid partieles remains stationary on the bottom of the vessel for longer than 1-2 see. They developed a eorrelation of the speed required to aehieve just-suspended eonditions as ... 

Maxflo T Wide-blade, high-efficiency impeller Blending, np and Nq varY with tjP an9le and Transitional flow, number of blades Simultaneous gas dispersion and solid suspension (like mining),... 

K.J. Myers, R.R. Corpstein, A. Bakker, and J. S. Fasano, Solids suspension agitator design with pitched blade and high efficiency impellers, AIChE Symp. Series, 90(299), 186-190, (1994). 

Typical values for the impeller clearance off the vessel bottom are 7/4 for hydrofoil impellers and 7/3 for pitched-blade turbines. Hydrofoil impellers may be a poor choice when solid suspension is accompanied by other mixing duties, such as liquid-liquid dispersion or gas dispersion. For such cases, a multiple impeller system consisting of a high-efficiency impeller in combination with a 45"" pitched-blade impeller should be evaluated. Small pitched blade impellers with a... 

The high-speed impeller or shear mixer is the most eommon equipment to prepare dispersions of solids in liquid. High speed shear mills and kinetie shear mills have retained their usefulness beeause of their ability to deagglomerate material that is not adequately dispersed in the premixing step. A high-speed shear mill is eomposed of two elements - a container and an impeller. These factors are important in the design ... 

Stirred-tank reactors equipped with high-speed impellers are normally equipped with two or four baffles designed to prevent the formation of a vortex and rotation of the reaction mixture with the stirrer, as illustrated in Figure 4. Each baffle has a width of between 0.08 and 0,12 times the tank diameter. In normal practice, there is a space between the tank wall and the baffle equal to about one-third the baffle width. It is also desirable to keep the baffles off the bottom of the tank to keep solids from depositing. 

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