Food freeze dryer

When the solution is rapidly frozen (cooling by 10-50 ℃ per minute), the grain size remains visible under the microscope; On the contrary, the crystals formed during slow freezing (1 ℃/min) are visible to the naked eye. Coarse crystals leave large gaps during sublimation, which can improve the efficiency of freeze-drying. Fine crystals leave smaller gaps after sublimation, which hinders the sublimation of the lower layer. The finished product of rapid freezing has fine particles, uniform appearance, large specific surface area, good porous structure, fast dissolution rate, and relatively stronger moisture absorption of the finished product. The drugs are pre frozen in two ways in the freeze-drying machine: one is to cool the product and drying oven simultaneously; Another method is to wait for the drying oven shelf to cool down to around -40 ℃ before placing the products. The former is equivalent to slow freezing, while the latter is between quick freezing and slow freezing, and is often used to balance freeze-drying efficiency and product quality. The disadvantage of this method is that when the product is put into the box, the water vapor in the air will quickly condense on the shelf. In the early stage of sublimation, if the plate heats up quickly, the large area of sublimation may exceed the normal load of the condenser. This phenomenon is particularly significant in summer. The freezing of the product is in a static state. Experience has shown that supercooling can easily occur to the point where the product temperature has reached the eutectic point. But the solute still does not crystallize. In order to overcome the supercooling phenomenon, the temperature at which the product freezes should be lower than a range below the eutectic point and should be maintained for a period of time until the product is completely frozen

The energy required for cooling and heating food is driven by a circulation pump and conducted to the shelf through a heat exchange medium, and then to the food. The cold source for cooling food is provided by the refrigeration system, and the heat source for heating food is provided by the heating tank. The switching between cooling and heating is achieved by controlling the electromagnetic valve switches of the cold and heat sources. When the temperature rises, steam enters the heating tank to heat the medium. A pneumatic three-way regulating valve is used to adjust the mixing ratio of the heat medium from the heating tank and the shelf reflux heat medium, and the opening and closing of the cooling water solenoid valve of the plate heat exchanger is controlled to control the temperature of the shelf. The system includes a heat medium heating tank plate heat exchanger, pneumatic control valve, cooling water solenoid valve, circulation pump, pipeline, solenoid valve, temperature sensor, etc

automatic control system

It has functions such as freeze-drying curve setting, vacuum pump testing and control, media temperature, food temperature, water trap temperature control, drying status detection, road removal, in-situ cleaning and sterilization, automatic protection and alarm.

Pneumatic system

Control pneumatic valves

In place cleaning and disinfection system

Used for cleaning and steam disinfection of dry box water traps