Originally Posted by
jbmorris
I am NOT a refrigeration expert and I only have a basic understanding of refrigeration operation, but I need some help in fixing a problem.
I work at a chemical plant in China which has a newly commissioned Frick 2-stage system which has 2 reliability issues: Moisture in the system and oil carryover from the Booster Compressor.
The system data:
- ***** R507 with Frick 13 oil
The Frick oil I don't know ,but someone will
- Booster suction pressure (Vac) -.15barG (-4.43"mg)
- Booster Discharge Pressure 2.1 barG (30.87 psig) Booster oil supply temperature 50Deg C (122 Deg F)
- Booster Discharge Temperature 60 Deg C
- High Stage Suction Pressure 1.85 barG (26.83 psig)
The oil separator has a 3 stage demister/coalescer but I have not seen the drawings of these yet...only relying on what I was told by our Chinese process engineer.
I have a couple of concerns I'd like opinions on:
1. How easily does the ***** disengage from the oil?
- At 45 Deg C, Frick 13 has density of 938.9 kg/m3 and specific gravity of 0.939
- at 70 Deg C R507 has specific gravity of 1.07
Usually pretty good if oil temp is 15deg C above saturated discharge temp
2. would running a higher oil temperature help
You could run it a bit higher but doubt it will reduce oil
carryover
3. We are contemplating raising our Booster suction pressure to slightly positive. What effects will this have on oil carryover and system operation.
- Right now our chillers on Booster suction operate at about -55 Deg C
- Our chillers on High stage suction operate at -16 Deg C
This could increase oil carryover , due to mass flow rate increasing through oil seperator & coalescers.
4. Is dP across our coalescers too high? Is it possible our biggest issue is gas velocity?
What is your dp acrross coalescers?
I'd appreciate your expert help on this problem.