Forced Circulation (FC)
It is the most used type of crystallizer in the industry. The crystal particle size is in the range of about 0.2-0.8 mm. By adding salt leg to the crystallizer, narrower range of crystal particles can be obtained. The recirculation rate, solution velocity in the heat exchanger tubes, steam velocity in the evaporation zone, pump blade tip speed, crystal residence time and the percentage of crystals in the crystallizer are important parameters to design the equipment.
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Advantages:
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Its design is simpler compared to other crystallizer types.
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Investment cost is lower.
Draft Tube Baffle (DTB)
Larger crystal grains are obtained compared to the FC crystallizer. Up to 2.5 mm crystal size can be reached. The crystallizer has mother liquor and slurry (solution-crystal mixture) outlets. Larger crystals are obtained due to the crystallizer structure. In order to obtain the desired crystal sizes, the growth and clarification zones must be carefully designed.
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Advantages:
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Larger crystals are obtained compared to the FC crystallizer.
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Particle size distribution is better than FC crystallizers.
Growth Type (OSLO)
Oslo type crystallizers are also called fluidized bed crystallizers. Since the crystal grains do not come into contact with the axial pump, secondary nucleation is prevented. Due to its structure, it is the type of crystallizer with the highest particle residence time. Crystal grains in the range of 1.5-5mm can be obtained.
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Advantages:
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Very large crystals can be obtained.
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Particle size distribution is much better compared to other crystallizer types.