Blending in the Laminar Regime

Calculate the minimum speed, Nc, for the cavern to reach the vessel wall from 

The minimum speed will be 24.4 rpm from Table 6-2 30 rpm is the next highest standard speed. 

Determine the number and location of the impeller(s). The height of the cavern will be approximately 40% of its diameter, in this case 1.2 m. Two impellers located at a clearance off the vessel base of 0.6 and 1.8 m will produce two intersecting caverns to a total height of 2.4 m which is higher than the maximum operating level. 

Calculate the power drawn by the two impellers and choose the motor size. The power drawn will be calculated from 

The next standard motor size is 7.5 hp, but this would mean that the impeller power draw will be 95% of the motor power. Choose a 10 hp motor. 

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Grenville, R. K., T. M. Hutchinson, and R. W. Higbee (2001). Optimisation of helical ribbon geometry for blending in the laminar regime, presented at MIXING XVIII, NAMF. 

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