# Gas Dispersion

**Category: **The Gas Dispersion ChemScale design procedure should be considered whenever there is gas in contact with a liquid.

**Size: **The size of an agitator problem for the Gas Dispersion ChemScale is the â€œEquivalent Volumeâ€. Equivalent Volume is equal to the actual volume multiplied by the specific gravity of the slurry.

**Difficulty:** The rate at which gas is sparged is the difficulty variable in submerged gas dispersion applications. This rate is the superficial gas velocity and is calculated by taking the sparged gas volumetric flow rate and dividing it by the cross sectional area of the tank.

**Dynamic Response: **The ultimate purpose of a turbine agitator is to achieve a desired process result. For Gas Dispersion applications, the dynamic response is the degree of Gas Dispersion and can be broken down fairly easy into the following categories:

**No Gas Dispersion:** Impeller is flooded (i.e. all the gas flows through the impeller and is not dispersed)

**Complete Dispersion:** Gas is completely dispersed to the tank wall

**Uniform Dispersion:** Gas is completely dispersed to the tank wall and circulated under the impeller

The ultimate role of a gas dispersion application is usually mass transfer. The agitator can affect the kla which will ultimately influence the mass transfer rate in the process.

### Typical Gas Dispersion applications are:

- Fermenters
- Strippers