I have a vessel with a top entering agitator without baffles. The vessel height is 2 m and vessel inside diameter is 1.5 m. The impeller type is three 60-degree pitched blades. Each blade has an inclination of 60-degress in respect to the agitator shaft too. The impeller diameter is 880 mm. The pitched blades are fixed to a cylinder that is 122 mm in height and with a 125 mm diameter. The width of the blade at the cylinder is 112 mm and at the end is 80 mm. The shaft diameter is 100 mm. The agitator has a velocity redactor of 1 to 10. The agitator has not driver and has not characteristics label. I want to use this vessel in the production of 50% calcium nitrate solution with a density of 1450 Kg/cubic meter and a dynamic viscosity of 1.35-1.8 cp. What will be the calculated power at 180 rpm and 360 rpm?
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Re: Calculating rpm power
10 May 2007 at 1:29pmThe answer is dont do it.
There is no way an impeller that large should ever be rotated at 180 rpm in a vessel that size. Without baffles, the liquid contents would swirl over the top to the tank an splash everywhere around the tank. At 180 rpm, without baffles, the impeller power draw would be about 7.8 kW, that's kilowatts, not watts. At 360 rpm, the power jumps to 61 kW. The mixer described is suitable for a much larger tank, not for one 2 m tall and 1.5 m in diameter, regardless of the contents. Baffles only make the design worse, because the power levels are about three times the levels without baffles.
Do not attempt to operate the mixer in the manner described!
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