The vacuum Crystallizer is also called an adiabatic evaporation crystallizer, which, compared with other crystalline devices, is special in that it can evaporate heat supersaturated adiabatic in a vacuum environment, so that the solution reaches supersaturation and crystallizes. And in the application process, the vacuum mold can be intermittent operation, can also be continuous operation.
The use of vapor jets is usually used to generate and maintain a vacuum. From the actual application results, the use of vacuum crystallizer can achieve a very low temperature, while the larger crystals can be obtained. Such a modern crystallization equipment, in which the reaction process can be divided into vacuum cooling (adiabatic evaporation) and crystallization of two processes.
Because of high vacuum, operating temperature generally low to room temperature or close to room temperature. Usually, in the use of this mold to operate the process, the use of raw materials are basically rely on the external heater of the device to preheat, into the equipment that began flashing steam cooling, that is, instantaneous evaporation and cooling. Therefore, the vacuum crystallizer equipment has both evaporation effect and cooling effect.
The concentration and cooling of the solution are carried out simultaneously to reach the metastable zone rapidly. Because of this, when we use the vacuum crystallizer, usually do not need to set another heater or cooler, this can avoid the complex heat exchanger surface of the crystallization of the heat exchanger corrosion, because of its simple structure, so low cost, high production capacity.
The typical structure is mainly composed of an upright cylindrical descriptor, the top of which is communicated with the condenser and the vacuum device, and a discharging port is opened at the cone bottom. In the process of operation, first add the appropriate amount of hot concentrated solution, and then the spiral slurry mixer and vacuum condensing equipment will be operated. When the pressure inside the container is reduced, the solution begins to boil and cool to the limit of the condensing device. Small grains, usually not larger than about 60, can be obtained by vacuum crystallizer.