There are many types of draft tube baffle crystallizers. According to the method in which the solution is supersaturated, there are many types of evaporation crystallizers and cooling crystallizers. According to the method in which the solution is supersaturated, it can be divided into evaporative crystallizer and cooling. The crystallizer can be used to divide the mother liquor circulation crystallizer and the crystal slurry (i.e., a mixture of the mother liquor and the crystal) in a circulating manner.
The draft tube baffle crystallizer can be divided into a continuous crystallizer and a batch crystallizer according to its operation mode. The commonly used crystallizer has a crystal tank which is a trough-shaped vessel, and a wall is provided with a jacket or a coiled tube inside the vessel. Used to heat or cool the solution in the tank. The crystallization tank can be used as an evaporation crystallizer or a cooling crystallizer. To increase the crystal production intensity, a stirrer can be added in the tank. The crystallization tank can be used for continuous operation or intermittent operation. The crystal is large, but the crystal is easy to form a crystal cluster, entraining the mother liquor, affecting the purity of the product. The crystallizer has a simple structure and low production intensity, and is suitable for the production of small batch products (such as chemical reagents and biochemical reagents).
When the drain pipe baffle crystallizer is operated, its feed liquid is added from the lower part of the circulation pipe, directly and away from the crystal.
After the crystal slurry at the bottom of the chamber is mixed, it is pumped to the heating chamber. The crystal slurry is heated in the heating chamber (usually 2 to 6 ° C), but no evaporation occurs. The hot crystal slurry boils after entering the crystallization chamber, so that the solution reaches supersaturation. Then, part of the solute is deposited on the surface of the suspended crystal grains to grow the crystal. The crystal slurry as the product is discharged from the upper part of the circulation tube. The forced circulation evaporation crystallizer has a large production capacity, but the product has a wide particle size distribution.