Agitator

What are tank mixers? How do you size a tank mixer?

Tank mixers are the same as tank agitators which is an agitator mounted on a tank to aid process operations with fluid mixing.

Tank mixers are sized by taking into account the conditions of the application & industry. This impacts material selection, electrical & mechanical loading and performance criteria. The customer will generally have a starting point and we work with them to build a picture of the overall requirement.

Required sizing details are:

• Tank Dimensions
• Duty Requirement
• Design & Operation Temperatures & Pressures
• Electrical duties
• Mechanical seal duties
• Mixing requirements such as Liquid-Liquid Mixing, Liquid-Solid Mixing etc
• Materials of construction

What is a slurry agitator?

A slurry is any liquid with some solids contained in the solution. A slurry agitator can handle such liquids and provides the mixing required.

A slurry agitator is often used to keep the solids in suspension to prevent settling out and forming on the base of the vessel or bulk tank before being transferred to the next stage of processing.

Examples would be in the API sector where solvents contain the active ingredient and are then filtered via a filter dryer.

What are the various agitator impeller types?

Standard Hydrofoils: these impellers are axial flow high efficiency  general purpose – they are designed to offer mixing with low Power requirements. They are also low shear and will not damage sensitive process media.

Wide Blade Hydrofoils: these impellers are axial flow high efficiency –  general purpose – they are designed with higher pumping in mind in comparison to the Standard Hydrofoils impellers. They are low shear and they use more power however they would still use less power in comparison to the  Pitched or Straight Blade Turbines.

Pitched Blade Turbines: are high pumping axial flow impellers, they are high shear so that could damage sensitive Process Media.

Straight Blade Turbines: are radial flow impellers, they are also high shear and are used for suspending solids where uniform suspension is required or for moving heavy liquids off the bottom of Tanks. Some applications of this are in the biotechnology sector.

RCI (Retreat Curve Impellers): can be used on Glass Lined Tank/Agitators, they offer lower shear than the Straight Blade Turbines with lower power requirements. They are usually used as a Bottom Impeller because they can be positioned very close to the curve of the bottom dish of the Tank, the blades curve upwards and they are also curved towards the end of the blades.

Gas Dispersion Impellers: are used for Mixing Gas into Liquids.

Rushton Turbine: is a gas dispersion impeller for mixing Gas into Liquids, such as hydrogenation and chlorination applications

Saw Tooth Disk or Dispersion Blade Impeller: is used for High Shear applications as they create lots of turbulence for breaking down solids. Typically used in the food sector, paints and other abrasive applications.

What is the difference between an agitator and a reactor?

The Agitator is a component for Mixing the contents of Reactor Vessels, typically found in API or Chemical sectors.

Which type of agitator is used for viscous liquids?

As the viscosity of the liquid media increases, the effectiveness of axial impellers decrease. For these applications, you use a number of impeller types better suited. These include UZ, Anchor, Helical coil and Transitional flow impellers

Batch mixing versus Continuous mixing?

• Batch mixing – if you need residence time for reaction, crystallisation, or storage capacity for downstream processing.
• Continuous mixing – if you have fast reactions or a fully continuous manufacturing process.
• Semi batch – using batch stirred tank vessels in combination with recirculation loops with static mixers or rotor stator mixers.