Freeze-drying installations

A typical grinding and sieving system (Fig. 2.5) produces dust which has to be collected. If in addition a CIP (cleaning in place) installation is installed, the total preparation equipment becomes a major part of the whole freezing and freeze drying installation. Figure 2.6 shows only the collecting container for the dust, which is sorted by size while below the container is the vibration transport system. 

Remmele et al. [3.55] studied with infrared spectroscopy the structure-hydration behavior of a 49.4 mg/mL lysozyme D20 solution with and without 10 % sucrose. The sample was cooled n in the measuring chamber to -100 °C and then connected to a freeze drying installation, after which the temperature of the sample was raised to +40 °C ... 

Fig. 2.2. Automatic filling of a product to be freeze dried in vials, which are cooled by LN2. In the installation the following steps are carried out with a speed of up to 9000 vials per hour Precooling of the vials down to -180 °C, filling of the vials, shock freezing of the product, placing the stoppers on the vials (photograph Groninger Co. GmbH, D-7180 Crailsheim).

Figure 2.7.1. shows the schema of a process for freezing pellets for freeze drying and Fig. 2.7.2 illustrates the details of the freezing chamber. Such installations are offered under the trade name Cryopel with throughputs between 10 and 250 kg/h. 

The leak rates of a freeze drying plant can be measured at the empty plant with the condenser cooled and the shelves heated by measuring the pressure rise per time multiplied by the installation volume in the dimension (mbar L/s). It should be noted, that the plant has to be evacuated for several hours, e. g. down to 10-2 mbar, before the pressure rise measurements, to avoid the influence of small amounts of ice and the desorption of gas from the surfaces. Furthermore, the pressure rise should be measured up to 0.2 or 0.4 mbar to detect possible gas desorption. Only if the pressure rise has been for some time proportional with time (Fig. 2.33.1), it represents a leak rate, which is defined as... 

AMSCO International Inc. [2.14] offers complete installations for VHP sterilization of freeze drying plants, which are programmable and automatic 4 to 400 g H202 per injection can be preset, as well as the parameter of the drying-, sterilization- and venting phases. The process is documented. Figure 2.47 shows an AMSCO-VHP generator. 

Freeze drying plants must be easily cleaned, a task which for pilot installations may be done by hand. This is difficult to document and one has to rely on the experience and conscientiousness of the operator. Gaster [2.16] presents a survey of advantages and disadvantages of cleaning methods from hand operation to spray sysfems with a sequence of... 

The merit of Malinin s work is the comparative study of water content of bones by reproducible methods. The measurement of water vapor pressure during the drying cannot be used dirctly to determine the RM, as Malinin correctly states. Measurement of the description rates (DR) provide a means to follow quantitatively the course of desorption drying. The method is described in Section 1.2.2, but cannot be applied in an installation used by Malinin because the condenser cannot be separated from the chamber by a valve. By using the data given in the paper of Malinin it is possible to estimate the freeze drying process of bone transplants as follows ... 

The installations have been taken over from the seller at (date and time). Before the take-over, the seller has successfully corrected complaints listed in appendix 1 of the takeover protocol. The freezing and freeze drying plant is registered as GF 50/95/1 and the loading and unloading system as GF 50/95/2. 

This does not sound to be very complicated, but it certainly is not a trivial job. It requires special skills and sophisticated installations in order to process materials in a suitable form, especially matrix certified reference materials. Imagine a few thousand bottles of freeze-dried orange juice with demonstrated homogeneity and stability for metals content In addition... 

This system is designed to clean the freeze-drying chamber and condenser with water for injection. Spraying with WFI at an inlet temperature of (provide value) °C effects cleaning of the chamber. There are jet rods installed in the drying chamber and the pathway to the condenser. The position of these rods as well as the distribution of the spray jets provides good coverage all over the interior surfaces of the chamber with WFI. The jet rods are equipped with full cone and flat jet nozzles. 

In this the refrigerant vapor is compressed mechanically. Two-stage motor compressors are used mostly in freeze-drying systems. This compressor is installed in a screwed-on housing together with an electric motor. 

---