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| CRYSTALLISATION |
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NaCI / Unhydrous Na2SO4 Crystallisation
During Evaporation, the concentration of Solute increases & when crosses solubility point causes Solutes to separate out as Crystals. However, since other salts also precipitate out depending on the solubility, the Purity of Major Salt is not at high level, so that it can be reused.
Glauber’s Salt (Na2SO4.10 H2O) Crystallisation
If the major portion of salt in effluent is Sodium Sulfate, it is recovered as Glauber’s Salt. The liquor is concentrated to about 25% concentration & taken to a crystallizer which is subjected to a very high vacuum of 8 – 10 Torr with help of high pressure steam jet ejector system. Due to such high vacuum, the liquor starts boiling till the temperature reaches 10 – 12 C. At this temperature the salt starts crystallizing.
The axial flow pump is used for circulation of liquor & ensures that the crystal size is even and there is no localized accumulation of crystals. The slurry is pumped to a hydro extractor / pusher centrifuge to separate the salt from colored mother liquor, which is either taken back to feed or solar pond. |
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| THICKNER / AGITATED THIN FILM DRYER |
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Feed from Evaporation reject is fed to the thickener by the Product Pump. The thickener is a jacketed vessel with steam in the jacket and the liquid in a thin film on the walls of the thickener. Feed is evenly distributed on the outer & inner wall of Thickener with a distribution mechanism. When it comes in contact with steam, the water gets evaporated & the Product is thickened.
The thickened product is then sent to Filter where sludge can be collected from bottom & Mother Liquor taken back to Thickener.
For Sticky liquids, Agitated Thin Film Dryer is provided where the evaporation surface is continuously wiped off by Agitator. |
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| SPRAY DRYERS |
Spray Dryer is a continuous method of drying solutions, slurries and pastes – in the shortest possible time. The drying is quick because the liquid is atomized as fine droplets in a chamber through which the current of hot air is passed.
Atomization, creates a very large surface area or the heat and mass transfer. And hence drying is very fast. The hot air coming in contact with the droplets increases its temperature up to around wet bulb temperature of air. |
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The above features make spray drying plant suitable for following applications:
Continuous production
Large throughputs
Heat Sensitive material
Fully enclosed operation
Guaranteeing purity
Depending on the application, it is possible to have variation in the drying circuitry and to offer a tailor made system to suit the purpose. |
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