How to control the pressure of pilot freeze dryer

Freeze vacuum drying is a new type of box structure introduced by a vacuum freeze dryer that combines a refrigeration system, a vacuum system, a thermal oil heating system, and a moisture dehumidification system, making maximum use of the material storage space in the box for drying.

The main methods for pressure control of pilot freeze dryers are:

1. Intermediate valve control method

It refers to achieving the purpose of pressure control by adjusting the cross-sectional area of the channel between the drying box and the water vapor condenser of the pilot freeze dryer to increase the partial pressure of water vapor in the drying box.

2. Water vapor condenser control method

It refers to the operating method of achieving pressure control by increasing the temperature of the surface of the water vapor condenser to reduce its condensation capacity, causing the partial pressure of water vapor in the drying box to rise.

3. Small butterfly valve control method

The purpose of pressure control in the box is achieved by intermittently opening or closing the valve between the water vapor condenser and the vacuum pump. The small butterfly valve control method uses the signal from the control system to control the opening and closing of the valve. When the pressure is higher than the set value (that is, the vacuum is too low), the valve is opened; when the pressure is lower than the set value (that is, the vacuum is too high), the valve is closed.

4. Aeration method

It refers to the operation method of controlling the air intake volume through a micro-regulating valve and introducing sterile air or nitrogen into the drying oven. This method is more commonly used in actual production.

The pilot freeze dryer is a small in-situ freeze-drying equipment, suitable for pilot workshops of pharmaceutical factories and small-scale production. It can also be used for freeze-drying of food, Chinese medicinal materials, etc. In-situ freeze-drying technology prevents contamination caused by the material transfer process and realizes the automation of drying and sublimation.