Applications

Process design of agitators

Agitation and mixing may be performed with several objectives:
1. Blending of miscible liquids.
2. Dispersion of immiscible liquids and gases in liquids.
3. Suspension of solid particles in slurry.
4. Enhancement of heat exchange between the fluid and the boundary of a container.
5. Enhancement of mass transfer between dispersed phases.

1.	Blending Operation
		The simplest and most common operation
		Mixing miscible liquids having dissimilar viscosity, density, temp.,concentration
		Hydrodynamics: flow-controlled, axial impeller
		Agitation purpose: to achieve homogeneity
		Applications: storage, reaction, heat transfer

2.	Dispersion Operations
		Mixing of immiscible phases (solid-liquid, liquid-liquid, gas-liquid, gas-solid-liquid)
		Agitation purpose:    - Disperse one of the phases    - Achieve an intimate contact between immiscible phases; one of the phases must be       dispersed in the other
		Dispersion: one phase is broken into small particles surrounded by the continuous liquid phase
		Hydrodynamics: flow-shear controlled, radial impeller
		Applications: liquid-liquid extraction, absorption, hydrogenation, chlorination

3.	Solids Suspension Operations
		The second most common operation
		Suspending insoluble solids in a liquid
		Hydrodynamics: flow-controlled, axial impeller
		Agitation purpose: keep particles suspended in the liquid phase
		Applications: crystallization, slurry feed vessels, solid catalytic reactions, solids dissolving

4.	Heat Transfer Operations
		Involve: heating, cooling and maintaining
		Hydrodynamics: flow controlled, axial impeller
		Agitation purpose: temperature uniformity and improve vessel side heat transfer coefficient
		Sizing an agitator to achieve a specific heat transfer coefficient is impractical
		Applications: heating, cooling, reaction, distillation, crystallization

5.	Gas-Liquid Mass Transfer Operations
		It is the transfer of mass from high concentration to low concentration (chemical industry application)
		Hydrodynamics: flow controlled, axial impeller
		Applications: filtering, crystallization, diffusion

Selection of Impeller Type
All mixing impellers produce both fluid velocity and fluid shear, but different types of impellers produce different degrees of flow and turbulence, either of which may be important, depending on the application
- Food & Beverage & Dairy
- Pharmacuticals
- Chemicals
- BioPharma
- Water treatment

MGT MIXING delivers various agitator types to meet diverse industries and tanks such as:
- Marine type agitator
- UZ type agitator
- Gate type agitator
- Anchor agitator
- Helical Ribbon
- Shear mixer (disperser disc, rotor stator, jet mixer)
- High efficiency and hydrofoil impeller
- MILK impeller
- Pitched Blade type agitator
- Coaxial systems
- Special applications
- Cristalizer

Determine Impeller Size and RPM Requirement
This depends on the kind of impeller and operating conditions described by the Reynolds, Froude, and Power numbers as well as individual characteristics whose effects have been correlated. For the popular turbine impeller, the ratio of diameters of impeller and vessel falls in the range, d/D,=0.3-0.6, the lower values at high rpm, in gas dispersion, for example.

Determine of Torque
In order for power (the rate at which work is done) to be meaningful there must be a standard of comparison. The most common unit to measure linear force is horsepower which defined as the energy to move 100 pounds 330feet in 1 minute.
Mechanical transmission products, such gearboxes, are evaluated on the basis of torque of rotation energy. Rotational power is defined as force times angular velocity. The angular velocity of a mixing impeller is normally measured in revolutions per minute (RPM).
The amount of torque applied to fluid mix is one of the most important factors in determining mixing results.

Torque is defined as:
Torque [Newton*meter]= (HP x 7126)/RPM