Scale Up - Match the tip speed of one mixer to that of second disperser with differing blade sizes. bioreactor are the agitator specific power (power/volume, P/V) and the superficial gas velocity (U s), which is the gas flow divided by the tank cross-sectional area.RPM - calculating rpm needed to develop a desired tip speed with a know blade diameter. How do you calculate scale up Scale-up calculations depend on the specific process or equipment being scaled.Tip Speed - calculating tip speed based on a know blade diameter and rpm.STEP by STEP Example : time to heat up a tank. Our Tip Speed Calculator addresses the most common uses of the tip speed equation. M weight of material to cool in the tank (kg) Cp specific heat of the material (kJ/kg/K) time required to cool down the tank (s) 4. The geometries of the bioreactor and the impeller influence the. However, the mass transfer within a process is highly dependent on the scale. Kinetics and thermodynamics are virtually unaffected by the reaction volume. Several factors play a role in a reliable bioprocess scale-up 1, 2. ![]() Lower speeds will reduce the vortex in low viscosity batches.įrom an operator's perspective, one blade may function adequately in several different diameter tanks, resulting in less operator intervention. Scalabilityan important aspect in bioprocessing. The wide variety and complexity of mixing tasks encountered in. Higher tip speeds may produce superior grinds in difficult to disperse products or counter insufficient flow in high viscosity batches. F undamental to the chemical process industries (CPI) -whether specialty or bulk chemicals, pharmaceuticals, food products, minerals processing, environmental protection or other products or activities -is the need for mixing. As with blade diameter, there are advantages to varying the tip speed of these dispersion blades. So if we take a 1 foot diameter (D) blade and turn it one complete revolution, a point on its edge would have travelled pi (Π) 3.14 feet.īy multiplying by rpm (n) we get the Tip Speed formula: TipSpeed = Π × D × nīlade speed for a high speed disperser is 5200 fpm (feet per minute).ĭisperser manufacturers normally target between 40 fpm (feet per minute) for the tip speed of their dispersers. Figure 2: Among the di erent vessels P/V can be kept constant in the range of 10.0 18.2 W/m3. Figure 3 shows the P/V values for different volume vessels. Scale-up of solid-liquid mixing based on constant power/volume and equal blend time using VisiMix simulation. This lower P/V value within the scale-up zone was chosen to reduce tip speed and shearing. where D 1 T 1 are the diameter of impeller and tank for small vessel and D 2 T 2 are diameters of impeller and tank for large vessel utilized for scale-up operation. You may remember from early math classes that the circumference (perimeter) of a circle is equal to: In this study, the CHO culture was scaled up with a constant P/V of10.9 W/m 3. ![]() Blade Speed (tip speed), measures how far a point on the outer most edge of the disperser blade travels in a given amount of time.
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