Maintenance; Compressor Oil - Atlas Copco GA 30+ Instruction Book

Instruction book
Energy recovery system in use (see drawing)
Compressor start-up
When the compressor is started up from cold, the oil temperature will be low. Bypass valve (BV2) shuts off
the oil supply through the heat exchanger (HE) and bypass valve (BV1) shuts off the oil supply through the
oil cooler (C0) to prevent the compressor oil from being cooled. The oil flows from the oil separator tank
(AR) through the oil filter(s) (OF) back to compressor element (E).
All energy input is used to rapidly warm up the compressor oil. No energy is recovered.
Maximum energy recovery
As soon as the oil temperature reaches the setpoint (opening temperature) of bypass valve (BV2), the valve
starts closing off the bypass over the heat exchanger (HE) oil flexible, gradually allowing the oil to flow
through the heat exchanger (HE). As the oil temperature rises to approx. 15 ˚C (27 ˚F) above the setpoint,
all the oil passes through the heat exchanger. The exchange of heat between the compressor oil and the heat
recovery water is maximum. The oil from the heat exchanger outlet flows via oil filter (OF), compressor
element (E) and separator (AR) back to the inlet of heat exchanger (HE). Bypass valve (BV1) bypasses the
oil cooler (C0) as long as the oil temperature remains below its setpoint.
Operation principle at different loads:
• Low consumption of recovered energy
The temperature of the oil leaving heat exchanger (HE) rises. When the temperature rises above its set
point, oil cooler bypass valve (BV1) will gradually allow the oil to be cooled in the oil cooler (Co).
• Recovery water flow too high/temperature too low
In this case, bypass valve (BV2) will open the bypass line allowing oil from heat exchanger (HE) to
be mixed with oil from separator (AR). Energy is transferred from the compressor oil to the water, but
at a relatively low temperature level.
Energy recovery system not in use
The oil circuit is the same as without installation of the energy recovery system.
No energy is recovered.
This situation should be considered as exceptional, e.g. in case of maintenance of the energy recovery
system or when no energy is required for a long period.
Run the unit unloaded for a few minutes before isolating the energy recovery system from the compressor.
Stopping the unit for a long period
In case of an open water system and/or if freezing temperatures can be expected, isolate the compressor
water system and blow it through with compressed air.
5.4

Maintenance

Compressor oil

For references used, consult section Energy recovery.
Oil change:
1. Run the unit until warm. Stop the unit, switch off the isolating switch and close the air outlet valve of
the compressor.
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