In addition to main elements (a compressor and heat exchangers) the refrigeration unit scheme also includes the ancillary equipment: linear, protective, circulating and drain receivers, liquid separators, oil separators, refrigerant and cooling medium circulation pumps, air purgers and others.
For the purpose intended ammonia RM receivers are divided into linear, circulating and drain ones. Receivers are horizontal or vertical cylindrical vessels with refrigerant inlets and outlets, an equalizer line, fitting and kit components.
Fig. 1. The linear receiver placed under the ammonia RM condenser.
They are meant for trapping the oil, entrained with a refrigerant from the compressor, and for smoothing the pulsation of refrigerant discharge vapour. On the principle of operation, oil separators are divided into washing (bubbling) and inertial (cyclone, screen and combined ones).
Fig. 2 The inertia-type oil separator as a part of refrigerating machine unit.
Pumps are applied for circulation of cooling water in circulating-water systems, of intermediate cooling medium and liquid ammonia in pump circulating systems as well. Overhung pumps are used for water and cooling medium circulation. Special leakproof pumps are used for ammonia pumping.
Fig. 3 The electric pump unit of leakproof centrifugal type. External view.
An air purger is intended for removal of the air, intruding into the ammonia RM system.
Fig. 4 GEA Grasso air purger. External view.
Liquid separators are added to the diagram for compressors protection from liquid refrigerant ingress and, therefore, from hydraulic shock.
Fig. 5 The liquid separator: а – diagram, b – general view.