Dave Dickey Forum Moderator 286 Posts
Re: How do I calculate the power required by a motor?12 August 2011 at 1:29pm
This question has missing information about the impeller, which has been estimated to do the calculations. In addition to tank diameter and straight side, impeller dimensions are needed, like impeller diameter, blade width, number of helical ribbons, impeller height, and pitch of helix. Estimated values are impeller diameter of 92 inches, blade width of 9.2 inches, 2 helical ribbons, impeller height 138 inches, and helix pitch of 92 inches.
I have never seen fluid viscosity in deci Pascal seconds, but that looks like 65 Pa.s, or 65,000 m Pa.s, or 65,000 cp. With those assumptions the impeller will draw about 620 hp, and a 750 hp motor recommended with a 220 mm diameter shaft. If the viscosity is really 650 m Pa.s or 650 cp, then the impeller power is112 hp, which could be handled with a 125 hp motor and a 127 mm diameter shaft. If the impeller is shorter, not as high, the power would be less, even for a 3,600 gallon batch, since impeller power is proportional to the submerged impeller height.
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