Agitators / Mixers for Vessels
Based on Viscocity and Specific Gravity of Liquid, design will depend on Reynold's Number.
Based on geometry of vessel, many factors for impeller can be decided.
For Disc Blade turbine, Flat Blade turbine and Backward Blade turbine, diameter of impeller depends on Width factor to Vessel Diameter. My program calculates Impeller OD and indictes it. For Paddle, Anchor, Anchor/Paddle and Gate: Diameter of impeller depends on Width factor to Vessel Diameter. My program calculates Impeller OD. Tip speed of impeller = 82.5 meters per minute or 250 feet per minute. Agitator Speed depends on tip speed of impeller. Program calculates RPM of agitator. My program then calculates the power absorbed for mixing. If the shaft RPM is less than 300, based on the absorbed power (output power of gearbox) and output RPM of gearbox, My program selects gearbox. My program indicates selected size of gearbox, which can be changed to next higher or lower value. My program then calculates diameter of shaft. You can select 4 types of materials for shaft. Indicated values of Yield Stress and Elastic Limit, in Kgs/ mm2 are as follows. Carbon Steel: Shear Stress 30.0, Elastic Limit 170.0. EN8: Shear Stress 55.0 Elastic Limit 246.0 EN24: Shear Stress 80.0 Elastic Limit 320.0 Stainless Steel: Shear Stress 50.0 Elastic Limit 230.0 You can select Safety Factor for calculation of shaft diameter. Torque at end of shaft = (746 * motor hp) / (2 * pi * (rpm / 60)) [in N-mt] Bending Moment = Torque * Safety Factor [in N-mm] Force at the end of impeller blade, Fm = Bending Moment / (0.75 * 0.5 * Impeller Dia)
My program then calculates maximum Bending Moment is at the end of shaft, Average Bending Moment at the end of shaft and Polar modulus of the shaft in cubic mm. My program then recalcuates Diameter of Impeller based on Critical Speed, and indicates recommended Impeller OD for Critical Speed. My program then reiterates till elastic limits is less than permisiible value by increasing shaft diameter. My program then calculates Critical Speed of Impeller. My program then reiterates till critical speed is more or less than 20% of agitator speed by increasing shaft diameter. My program then indicates Final values after calculation of Critical Speed, Shaft RPM, Impeller Diameter and Shaft Diameter. |