Liquid nitrogen technology benefits freeze-dryers - Lyophilization Articles & Reports

Liquid nitrogen technology benefits freeze-dryers
Edited by: Processingtalk Editorial Team on 5 April 2005
Renowned freeze-drying experts Usifroid, in collaboration with Air Liquide, the world leaders in cryogenic applications, have developed and optimised a design to apply liquid nitrogen to freeze dryers.
In a freeze dryer, liquid nitrogen, or 'LN2', is used in two places: in a cryogenic heat exchanger, to cool down the silicone oil circulated in the shelves; and in the condenser coils, to trap the vapour into ice.
Cooling energy comes from both a change of state, as liquid nitrogen evaporates into gas, and a change of temperature, as the gaseous nitrogen temperature rises.
The combination of these two changes gives savings of over 50% of the LN2 consumption compared to systems with temperature change alone.
LN2 offers many benefits to the lyophilization process and production.
Cooling power is almost constant throughout the temperature range and is available instantly, with a lower minimum temperature that allows for specific recipe or organic solvent trapping.
Temperature and power control is more accurate and more flexible for better product quality and reproducibility.
A much simpler system offers ease of operation, with increased flexibility and better reliability.
Compared with conventional systems using reciprocal compressors, LN2 systems offer much greater reliability while requiring much less maintenance.
Compared with screw compressors, which are more reliable than reciprocating compressors, LN2 systems are still superior, offering space savings, a reduction in noise level, and requiring no particular expertise to maintain.
Usifroid started developing LN2 systems in collaboration with the Air Liquide Advanced Technology Centre in 1991, and was the first to deliver a large industrial lyophilizer using liquid nitrogen only.
LN2 has been increasingly the chosen solution and today, with over 60% of Usifroid production-scale freeze dryers being equipped with LN2 systems.
Usifroid has also developed an evaluation programme to compare LN2 with reciprocating compressors and screw compressors with non-CFC refrigerant, helping you engineer the most suitable system for your project.
Production-scale freeze dryers with LN2 and other Usifroid products are available in the UK and Ireland through freeze drying specialists Biopharma Process Systems.