Biotechnology Roche / Germany

Planning / Implementation / Main components:

Compressor by Bitzer Kühlmaschinen GmbH

Refrigerant:

Propene (R 1270)

System start-up:

2006

One important process in the research and production of biotechnological products is freezing and defrosting substances for transport and storage. For the pharmaceuticals company Roche the contractor Peter Huber Kältemaschinenbau developed a chiller run on propene using a reciprocating compressor by Bitzer.

Demands:

For the (de-)frosting processes Roche uses tanks with a volume of 300 l which are cooled down to -40°C in a clean room atmosphere. Here the company wanted an efficient refrigeration system to cope with fast changes in temperature between -50 and 130°C with an accuracy of +/- 1 K, with automatic drainage and refilling of the tank's cooling jacket. Furthermore, compliance with the Roche Environment Protection Guidelines restricted the choice of refrigerants to substances that protect the ozone layer and the climate.

Solution:

To meet these requirements, the contractor implemented a chiller that works with a small charge of 1.8 kg propene. The core element of the system is a two-stage semi-hermetic reciprocating Bitzer compressor, which is designed for use with propene. After being brought down to a temperature of -60 to -30°C, the propene then cools the silicone oil circulating in the cooling jacket. The output is 12 kW at a secondary refrigerant outlet temperature of 0°C, and 6.5 kW at -40°C.

Type of system

Chiller

Refrigerant:

Propene (R 1270)

Refrigerant charge

1,8 kg

Secondary refrigerant

Silicone oil

Evaporating temperature

-60 °C

Condensing temperature

-30 °C

Cooling capacity

6,5 to 12 kW

Main components

A two-stage semi-hermetic reciprocating Bitzer compressor, a plate heat exchanger acting as evaporator, a water-cooled coaxial condenser and a control unit (Modbus)

Special features / Comments

The safety concept of the system comprises separate refrigeration circuits into several sections so that in the event of a burst pipe, any refrigerant leak is limited to the affected section rather than the complete charge.