PAT tools and process optimisation
Comprehensive process monitoring is necessary in the development and subsequent production of high-value products, particularly in the biotech and pharmaceutical sectors, for internal quality assurance and regulatory compliance documentation.
Process analytical technologies, which include everything from product temperature sensors to online mass spectrometers, provide insight into complex processes and enable stable drying processes.
As a technology leader, we provide the following tools for our customers:
- LyoCam 2.0 – Camera system
- WTMplus 2.0 – Wireless product temperature measurement
- RFID reader
- LyoCoN – Controlled nucleation
- MTMplus – Manometric temperature measurement
- Capacitive sensor in addition to Pirani-gauge
- LPCplus – Process visualization
Industrial-scale freeze-drying requires robust processes that are initially developed on pilot systems and then scaled up. The objective is to develop drying recipes (profiles of vacuum and shelf temperature versus time) that allow the best possible quality to be achieved in the shortest possible time.
Pilot systems must therefore have the same technology and geometry as the subsequent production freeze-dryer, such as rectangular product chambers and shelves, cooled and heated by liquid media.
The following table lists the parameters used by Christ for process control and monitoring. When used together with basic recipes stored in the freeze dryer control system for various products, an automatic, self-optimising process can be achieved.
| Feature | Function | Area of application |
|---|---|---|
| WTMplus 2.0 T-sensor wireless | Product temperature measurement, wireless | Process monitoring, determination of completion of drying |
| T-sensor wired | Product temperature measurement, traditional wired | Process monitoring, determination of completion of drying |
| Lyo-Rx | Measurement of electrical resistance shows freezing-/melting point | Determination of freezing point, self-optimising sharp cycle possible |
| p (Pirani) | Drying vacuum, dependent on gas type | Display of drying vacuum |
| p (capacitive) | Drying vacuum (independent of gas type) | |
| dp/dt pressure increase test | Measurement of pressure increase in product chamber by closed intermediate valve | If the value falls below an adjustable limit value, the end of the main drying process is reached; can be used for automatic switching to the secondary drying process. |
| dp/dt, manometric pressure measurement (MTM) | By measurement with rapid-closing intermediate valves, determination of T at the sublimation interface, and further thermodynamic characteristics | Understanding the process, avoiding collapse |
| Comparative pressure measurement | Indicator to determine the end of drying of the main drying process | Process monitoring |
| Controlled nucleation | Uniform freezing for homogenous drying and product properties | Ice fog + over-pressure method |
| LyoCam 2.0 | Visual | Drying quality, artefacts, faults |
| Scale | Measurement of product weight during drying | End of drying, sublimation speed, can be used for further switching to post drying |
| Annealing | Also referred to as tempering (crystal growth by moderate heating of the frozen product) | More rapid drying without collapse, improved structure |
| dTfreezing | Lowest product temperature before switching over to Freezing -> Main Drying | Reliable freezing, No defrosting or collapse of the product in entry to main drying |
| dTmain drying | Lowest product temperature before switching over to the next process stage | Reliable drying (main drying and final drying) |
| Ice condenser temperature | Display and check whether desublimation is possible | Onset while large amounts of steam are present and stabilisation indicates completion of drying |
| Tshelf ON / OFF | Heating fluid temperature in shelf, flow and return | Difference indicates energy consumption due to sublimation |
| psafety | Pre-selectable safety pressure | Product protection, Sharp cycle, limited by psafety |
| pAlarm | Pre-selectable alarm pressure | Product protection, Sharp cycle, limited by palarm |
