GEA Liquid Nitrogen Freezer

Not only does the process prevent the deterioration of product properties, the subsequently produced pellets can then be stored frozen and distributed, or transferred to a freeze dryer to maintain their characteristic properties and, in the case of microbial cells, their viability, at ambient temperature.

Often used to freeze liquid products for easy storage and handling, GEA’s Liquid Nitrogen Freezer (LNF) offers extremely fast processing for optimal freezing and subsequent lyophilization. In combination with GEA’s RAY freeze dryers, the nitrogen-frozen pellets deliver superior product quality (in terms of colony forming units) and freeze-drying cycles that are substantially shorter (<24h) than those achievable with slab freezing systems.

Compared with other freezing methods such as blast freezers or drum freezers, the LNF is compact, comprises almost no moving parts and is very easy to maintain and clean. It’s clean-in-place (CIP)-compatible but can also be disassembled and sanitized.

Main components of the LNF include the following:

•    Liquid feed arrangement to feed the liquid droplets into the pelletizer through feed tubes
•    Pelletizer tank with a conical outlet to freeze the pellets in liquid nitrogen at –196 °C
•    Motorized agitator to ensure that the liquid nitrogen is constantly moving to prevent agglomeration
•    Liquid nitrogen supply valve and control
•    Screw conveyor to remove the frozen pellets from the pelletizer tank
•    Ventilation system to prevent nitrogen gas escaping into the production room.

Furthermore, as liquid nitrogen freezing forms droplets, the frozen product is dust free and free flowing, resulting in almost no product loss. Key benefits include:

•  Very quick freezing
•  Minimal product loss
•  Simple and reliable operation
•  Easy to clean
•  Free flowing product.

The feed and discharge arrangements can be dismantled and separated for cleaning and sterilizing, and the pelletizer is available with a CIP system. The modular plant can be supplied in three different industrial sizes for throughput capacities of 100–500 L/h and a pilot unit for batch operation. The pellet size is typically 2–4 mm.

Liquid nitrogen freezing is the perfect processing solution for expensive and/or sensitive products, but requires 3–4 kg of nitrogen per kilogram of product frozen, so operating costs should be considered during the evaluation procedure.

The size of the spherical droplets formed during the procedure is very uniform and mainly dependent on the viscosity of the liquid being frozen.

Offering the same fast freezing and high throughput functionality as the full-scale plant, GEA also offers a pilot-scale version. Designed with research and small-scale applications in mind, customers can rent a unit to run tests and trials at their own location before investing in an industrial-size unit.

As bacterial cultures rapidly start to lose activity after harvesting, it is a clear advantage to be able to freeze rapidly and conduct tests on site next to the fermentation line. With the LNF-6 pilot plant, we can deliver cost-effective and demonstrable benefits.