12-10-2012, 04:42 PM
Mechanically Agitated Vesels
Mechanically Agitated.ppt (Size: 2.57 MB / Downloads: 54)
Vessels
Typical vessels- vertical circular cylinders
Rectangular tanks also used
Impeller consists of a hollow shaft and a flat blade turbine.
Promotes rapid reactions between gases, liquids, and solids in high-pressure reaction vessels.
Turbine creates suction, drawing gas in at the top of the shaft. Gas travels through the shaft and exits as bubbles that are thoroughly dispersed by the turbine blades..
Agitation and Mixing
To suspend solids
To blend miscible liquids
To make homogenous solid mixtures and pastes
To disperse gas through liquid
To make emulsions from immiscible liquids
To promote heat transfer
Types Of Mixers:
Static Mixers
No moving parts, continuation of pipe
Divides stream until molecular diffusion prevails
Used for gases, low viscosity liquids
Dynamic Mixers
Movement of agitators/mixers/homogenizers responsible for mixing
Can be used for solids, liquids and gases
Additional power required running motors and other accessories
Hydrofoil Left hand (LH) propeller
In majority of industrial mixing applications
A Clockwise rotation (motor end), creates a downward flow to produce optimal tank turnover.
Flat blade turbine
Offers very high torque,
blending at the expense of efficiency, or when high shear is required.
Ex: liquid-liquid emulsions, high intensity solids scrubbing.
Concave blade CD-6 Impeller
For gas dispersion applications
Has a unique blade design that handles higher gas rates for improved process efficiency.
Characterized by curved pipe sections mounted to a disc.
Results in a lower power number (ungassed = 3.20) and increased efficiency.
Paddles
Versatile form of turbines- contains as many forward agitators as the backward.
This pattern allows better and speedier mixing.
Paddle agitator can be used for small batch precision mixing as it can take as little as the 20% of the maximum capacity.
Suitable for both wet and dry ingredients, it is recommended for fertilizers, chemicals and minerals.
WHAT IS VORTEX?
A vortex is a spinning, often turbulent, flow (or any spiral motion) with closed streamlines.
It is a flow involving rotation about an axis.
The shape of media or mass rotating rapidly around a center forms a vortex.