GEA Grasso - 3 Description of Design and Function; Brief Description; Use; Design

OPERATING INSTRUCTIONS
CO
2
/NH
3
CASCADE UNIT
250 - 1000 KW
34 _551511_om_kas_gbr_1_.doc
3 DESCRIPTION OF DESIGN AND FUNCTION
3.1 Brief Description
3.1.1 Use
These 2-stage CO
2
/ NH
3
cascade units are highly efficient industrial refrigerating plant and as such are suitable for
use within the low temperature range with evaporating temperatures between -40 and -54°C, e.g.. for freezing
apparatus in the food indutry or for drying processes.
and NH are used.
The natural and environmentally friendly refrigerants CO
2 3
3.1.2 Design
low temperature and an NH
The cascade unit consists of a CO
2 3
high-temperature level with the following main
components:
(A) CO
screw compressor unit
2
(B) CO
liquid separator
2
(C) CO
pump unit with 1 or 2 parallel refrigerant pumps
2
(D) CO
expansion device (not illustrated)
2
(E) CO
2
-NH cascade heat exchanger module
3
(F) automatic oil return system of the CO
side (not illustrated)
2
(G) automatic oil return system of the NH
side (not illustrated)
3
(H) NH
screw compressor unit
3
(I) NH
injection system
3
(J) CO
condenser
2
(K) auxiliary refrigeration unit for CO
separator
2
(L) low voltage system with control
(M) joint stable baseframe
fig. 25: Diagram of the main components of the CO
2
/NH cascade, Part 1
3