The working principle of a crystallization kettle is mainly based on the solubility changes of the solution under specific conditions to drive crystal growth. The specific process is as follows:
Dissolution and saturation: The material (solute) to be prepared is usually added to the solvent in solid form to form a solution. When heating the raw materials and solvents, solubility usually increases with increasing temperature until reaching saturation.
Cooling and supersaturation: Next, control the cooling system of the crystallization kettle to gradually lower the temperature of the solution. When the temperature drops below the solubility curve, the solution becomes supersaturated, which means that the amount of solution contained in the solution exceeds the amount that can be dissolved at that temperature.
Crystal growth: In a supersaturated state, solutes begin to precipitate from the solution and gradually form crystals. This process is spontaneous because after the precipitation of crystals, the solute concentration in the solution decreases, approaching the solubility curve until a new equilibrium is reached.
Stirring and mixing: The stirring device in the crystallization kettle plays a crucial role by continuously stirring the solution to ensure uniform distribution of solutes in the solution, thereby preventing excessive concentration or precipitation of solutes in local areas. Stirring also helps to disperse the formed crystals, preventing them from sticking together or forming excessively large crystals.
Control and regulation: The crystallization kettle is equipped with various control and regulation devices, such as temperature monitoring devices, pressure sensors, stirring speed controllers, etc. These devices can adjust operating parameters as needed (such as temperature, pressure, stirring speed, etc.) to optimize the crystallization process and obtain the required crystal quality and yield.
In general, the crystallization kettle allows solutes to precipitate from the solution and form crystals by controlling the temperature, stirring, and mixing conditions of the solution. This type of equipment is applied in industries such as chemical, pharmaceutical, and food to prepare various high-purity solid products.