Crystallization equipment can be effectively divided into two categories during use. A crystallizer that removes a part of the solvent and a crystallizer that does not remove the solvent can be effectively operated at normal pressure or under reduced pressure during operation.
Crystallization equipment can be effectively divided into batch operation and continuous operation to a certain extent. When used, it will effectively precipitate crystals from the unsaturated solution of solid matter. Under normal circumstances, it will effectively pass through its unsaturated solution → saturated solution → Supersaturated solution → nucleation → crystal growth and other processes.
Crystallization equipment principle explanation
1. During the operation of the crystallization equipment, its constant temperature evaporates, so that the volume of the solvent can be reduced, and the solution represented by the p point in the course of operation will effectively become its saturated solution, that is, become its The solution represented by point A on the S curve. At this point, if the evaporation stops and the temperature does not change, the solution at point A is in a dissolved equilibrium state, and the solute does not precipitate from the solution.
2. If the crystallization equipment continues to evaporate, it will be effective during the operation as the amount of solvent continues to decrease. At this time, the solution is a supersaturated solution, and the solute can naturally precipitate crystals from the solution.
3. When the crystallization equipment is operating, its capacity should remain unchanged, which will cause the temperature of the solution to decrease. If the temperature of the unsaturated solution represented by point P is reduced from t1°C to t2°C, the original P point The solution shown turns into a saturated solution represented by point B on the S-curve. At this point, if the cooling is stopped, the solution at point B is in a dissolved equilibrium state, and the solute does not precipitate from the solution. If you continue to cool, from t2 °C down to t3 °C, then the original point B solution must be replaced with B 'point that the solution is a supersaturated solution, the solute can naturally precipitate crystals from the solution.
Evaporation crystallization equipment
The evaporative crystallization equipment is one of the commonly used operating units in the pharmaceutical and chemical process during the operation of the evaporation crystallization process. During the process of use, it is very commonly used in the production process of almost all crystalline drugs. . The current crystallization of evaporation commonly used by companies is mainly convection and forced circulation. The above two types of evaporative crystallizers are mostly evaporatively crystallized by forced circulation.
The main principle of the evaporating and crystallization equipment is that the material liquid is effectively heated by the pump under the action of the pump, and the whole evaporator is evaporated. After so many cycles, the solution concentration exceeds the solubility at the temperature. The solute crystallizes out, and in this state a solution of the crystal that has appeared continues to be heated repeatedly under the action of the pump. The evaporating process is repeated until a large amount of crystals are formed, and the solution becomes a very thick suspension of crystals that cannot be circulated. Many kinds of drugs are heat-sensitive and the hardness of crystals is high.