Exp 4 Flashcards
What is the aim of the study described?
To study the effect of various agitators on mixing of aluminum salts with water, measure the power number for a mixing system, and relate the power number and Reynolds number in a mixing system.
What is the principle behind mixing in industrial processes?
Mixing is generally performed by a rotating impeller in a vessel and is crucial for the production of various products in multiple industries.
In which industries is mixing an essential operation?
- Food
- Petroleum
- Mining
- Pharmaceutical
- Pulp and Paper
- Chemical
- Environmental cleaning
What is the structure of the mixing system described in the experiment?
A vertical cylinder with a wide open top and specific inner diameter and height.
What types of impellers are used in the experimental setup?
- Radial flow mixing device (turbine)
- Axial flow agitator (marine propeller)
What is the formula for power utilized for mixing?
P = 2πTrNT
What do the variables in the power formula represent?
- P: Power utilized for mixing
- T: Torque (N.m)
- r: Radius of impeller (mm)
- N: Speed of impeller (rpm)
How is power consumption correlated to impeller speed?
By means of dimensionless numbers, Power number (Np) and Reynolds number (NRe).
What is the formula for Power number (Np)?
Np = (P)/(N^3 * D^5)
What is the formula for Reynolds number (NRe)?
NRe = (ρ * N * D^2)/μ
What do the variables in the Reynolds number formula represent?
- ρ: Density of the fluid
- N: Speed of the impeller
- D: Diameter of the impeller
- μ: Viscosity of the feed (Pa.s)
How is Kp calculated for each impeller?
Kp = Ne * NRe
What is the purpose of incorporating baffles into the mixing system?
To avoid vortex formation which leads to improper mixing.
Fill in the blank: The impeller is placed on the vessel centerline at ______ of the liquid height.
1/3rd
