How can I improve stirring! ! !
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We have a crystallization tank. During its initial design, due to the lack of expertise on the part of the designers, a closed-type enamel tank was used. As it was a closed system, an impeller-type agitator was chosen for mixing. For this 5000-liter crystallization tank, a single layer of impeller agitators was used; when the amount of material being processed was large or when the crystallized material was quite thick, it often happened that the material couldn’t be properly mixed. If the crystalline particles were large, increasing the agitator speed could help improve the situation, but this didn’t work when the crystals were in powder or needle form, as the material would often stick to the walls of the tank. It’s not possible to replace the crystallization tank at the moment – do anyone have any other good solutions? I once thought about adding an extra layer of stirring, but it’s not easy to do since it’s made of enamel!
The bottom layer uses anchor-type elements, while straight paddles are installed on top; the discharge valve is a rising-angle valve. A heating element is placed around the discharge valve.
I wonder what method you use for crystallization? It is not impossible to use paddle stirring for thick crystalline materials; paddle stirring operates at a fast speed, requires a powerful motor, and delivers good mixing results. However, if the material often sticks to the walls, a spiral scraper is required; this scraper rotates coaxially with the mixer, but the mixing speed must be significantly reduced. At very low rotation speeds (2 revolutions per minute), a single impeller mixer is essentially ineffective, and therefore an impeller mixer cannot be used as a mixing method in such cases.
Change the mixing device to use a spiral mixer, or adjust the feeding speed
There are various ways to do this, with the principle being that the projection of the mixing area on the plane passing through the center line of the mixing shaft should be as small as possible in order to reduce the mixing resistance.
Since it is a closed enamel kettle, it is not possible to replace the large agitator, and the crystallization method is cooling-induced crystallization.
Stirred with a screw conveyor, variable frequency. Start with a higher speed, then reduce it later.
It must have a continuously variable transmission to meet the requirements mentioned above.
For crystallization tanks like yours, the largest size we have built is 40 m3. It is recommended that you use anchor-type impellers
I’m not sure what the maximum viscosity of the materials you use can reach. For those that are slightly sticky, use anchor or frame impellers. It’s best to bring a scraper. The rotation speed should preferably be kept below 20 rpm. If it’s particularly sticky, like industrial adhesive tape. It is estimated that screws and belts will be used (usually not for crystallization). The rotation speed should be 3~5 rpm.