1. Drying Oven
The drying box constitutes the core component of the lyophiliser, its function being to house the material to be dried. The container is characterised by its vacuum-sealed, low-pressure design. Typically, it is manufactured from 304 or 316L stainless steel, a material that exhibits excellent corrosion resistance and facilitates ease of cleaning, thereby conforming to the stringent standards set for food and pharmaceutical grade containers. The interior of the drying oven is typically equipped with shelves for the purpose of materials placement, and the materials utilised for these shelves, in conjunction with the method of temperature control, exert a significant influence on the efficacy of the drying process.
2. Refrigeration System
The refrigeration system is responsible for rapidly lowering the materials' temperature to below the eutectic point, thereby ensuring their stability at low temperatures. The apparatus is composed of the following components: a compressor, a condenser, an evaporator and a throttling device. The refrigerant circulates within the system in order to achieve a state of low temperature by absorbing the heat of the material.
3. Vacuum System
The vacuum system is instrumental in establishing the requisite low-pressure environment for the process of sublimation drying. This system typically comprises a vacuum pump, vacuum pipeline, and vacuum valve. The vacuum pump plays a pivotal role in this process by reducing the internal pressure within the drying box through the process of air pumping, thereby inducing the direct sublimation of ice crystals into water vapour.
4. Heating System
The heating system is responsible for providing heat for the sublimation process, with common heating methods including silicone oil circulation heating and electric heating. The application of silicone oil circulation heating has been demonstrated to exhibit high temperature uniformity, thereby rendering it suitable for use with heat-sensitive materials. The temperature range and heating rate of the heating system can be adjusted according to the material characteristics.
5.Cold Trap
The condenser plays a pivotal role in the sublimation process by capturing the water vapour that is generated and converting it into liquid form. This process is essential in maintaining the desired vacuum level and preventing the accumulation of water vapour, which could potentially compromise the integrity of the system. The condenser typically employs low-temperature refrigeration technology to facilitate efficient condensation.
6. Control System
Contemporary freeze-drying apparatus is generally equipped with state-of-the-art programmable logic controller (PLC) systems, which facilitate precise regulation of critical parameters such as temperature, vacuum, heating power, and duration. The control system is equipped with a range of features, including programmed control, data recording and exporting, and remote monitoring capabilities.
