Mixing and Agitation
- Mild agitation is obtained by circulating the liquid with an impeller at superficial velocities of 0.1-0.2 ft/s and intense agitation at 0.07-1.0 ft/s.
- Intensity of agitation using impellers in baffled tanks is measured by power input and impeller tip speeds, as given in the table.
- In-line blenders are adequate when a contact time of 1-2 s is sufficient, with power inputs of 0.1-0.2 hp/gal.
- Power and Tip Speed requirements for agitation in baffled tanks
| Operation |
Power Needed hp/1,000 gal |
Tip speed ft/min |
| Blending |
0.2 - 0.5 |
|
| Homogenous reaction |
0.5 - 1.5 |
|
| Reaction with heat transfer |
1.5 - 5.0 |
10 - 15 |
| Liquid - liquid transfer |
5 - 10 |
15 - 20 |
| Liquid - gas mixing |
5 - 10 |
15 - 20 |
| Slurrying |
10 |
|
|
