View Full Version : flooded evaporator oil return

17-01-2013, 04:27 PM
Hello everyone.
A open-type screw ethylene glycol unit.10℃ inlet 0℃ outlet.refrigerating capacity is 4300kW.I want to use flooded evaporator.but I am afraid the oil can't return.The compressor is open-type compressor.and the oil sparator is big enough.
which is better, flooded evaporator or thermosyphon evaporator.How to resolve the oil return? use auto-oil receiver or injector?

17-01-2013, 05:34 PM
take a look at a sabroe skid set up


and dont laugh at me first video attempt [ I'm certainly no cool Monkey Spanners ]

LPR, flooded evap and hydraulicly operated oil return injection system

may suit your needs and you can mimic the design

R's chillerman

17-01-2013, 08:28 PM
Hi Chiller what you got strung all over the PAC in the video? Is it a climacheck system or some such?

17-01-2013, 08:35 PM
yeah sort of mate was logging various temps / pressures

commisioning failed

kept shutting down intermitently on low lpr level

turned out during high load the violent vapour rising up the level indicator gave false readings

cure was baffles fitted to make bubbles smaller

R's chillerman

Marcos Rogerio
08-02-2013, 02:35 PM
Hi Joanna, take a look in the link below.



08-02-2013, 04:48 PM
What refrigerant is it running on?

We are talking big size, or slow moving liquid, if I understand you correctly and you want a 10 kelvin difference between the inlet and outlet of the ethylene glycol in the evaporator?

I'm not familiar with thermosyphon evaporators, but I have a fair knowledge of flooded evaporators and their operation.

A tad more information would be nice before I make my judgements.

I'm guessing we are talking about *****, where the oil rich part will be on top, so I would suggest what we call an "oil boiler" where warm liquid from the pilot receiver passes on one side, and a static level from the evaporator is on the other side.
Every time the pilot receiver is drained, warm liquid passing through the heat exchanger causes the liquid on the evaporator side to boil, and lift oil up into the suction of the compressor.

To more easily explain, consider these drawings

In this first picture we have a basic evaporator, with a surge drum on top... Notice the vertical pipe on the side, this is the oil boiler.


In this second drawing I have marked out a few basic things just to be sure :)


And in this last drawing I have explained the function of the oil boiler.


To be sure that the oil boiler functions properly, it is essential that the refrigerant charge in the system is balanced so that at standstill, with no boiling in the system, the level must be near the level of the sight glass, doesn't need to be in the middle of the glass, but a maximum of 10 cm below the glass is what I have found to be the critical point.

hope this helps :)

09-02-2013, 12:29 AM
4000 odd Kw glycol chiller, would make economical sense to apply ammonia with a large AlfaLaval plate HX and surge vessel above, flooded evap, gravity thermosyphon feed.