The top entry agitators arose from the need to control mixtures at runtime or heat transmissions in the reactors and evolved by modifying and optimizing blade profiles.
In contrast, submersible mixers were developed by submersible pump manufacturers, who saw this possibility when applying a propeller to the submersible motor.
Large diameter impellers at low speeds provide better mixing throughout the liquid volume. Therefore, solid fillets distributed at the bottom of the tank and accumulated in the corners will be eliminated.
In addition, the top entry agitator provides vertical flows with direction and direction opposite to the action of gravity so it acts with greater speed and efficiency on the suspension of solids, fibers, etc. since the cause of stratification is the force of gravity.
Consequently we have a better mixing and much lower power levels.
There are no submerged electrical components.
No submerged bearings and seals are required.
On the other hand, corrosive and hot liquids can be used.
It is not necessary to stop the installation to do the maintenance work.
Furthermore, with a good design, it is not necessary to empty the tank for cleaning solids.
A practical example of top entry agitators:
Buffer tank section 9×9 m and liquid height 5 m. It is a question of homogenizing the residual water of correntias that it contains.
With submersible agitators, depending on the abacus used, 25W/m3 will be required.
The volume is 405 m3 405×25 = 10.125 W.
An 11kW submersible agitator with 600 mm propeller diameter is taken at a speed of 351 rpm.
With this we obtain a flow of 3977 m3 /h that will generate 9,8 renewals/hour.
With top entry agitator a thin profile propeller of high efficiency is taken. The diameter is 2500 mm and at a speed of 30 rpm. Consequently it will provide a flow velocity at the exit of the propeller of 0.54 m/s, a flow of 9535 m3 /h. This will generate 24 renewals/hour and a mixing time of 3.33 min. The drive motor will be 2.2 kW.
Undoubtedly, with 20% of the power you get a 239% flow and much better oriented and distributed.
