collecting oil in evaporator

[aygul]

Hello everybody,
In chiller with water cooled condenser, compressor oil is collecting into the evaporator. How can we send this oil to the compressor carter? Isthere any solution without changing evaporator?

Thanks for your helps....

Aygul

[Tejbir Singh]

In chiller with water cooled condenser, compressor oil is collecting into the evaporator. How can we send this oil to the compressor carter? Isthere any solution without changing evaporator?

What the size(TR) of chiller?
Check the gas it will be short. for temporary solutions

Is there any unloading system in compressor?

If yes than unload the compressor all the oil in evaporator will move to compressor.this is temporary solution.

[chemi-cool]

Hi aygul.

There are a few solutions.
You can install an oil sepatator after the compressor.
You can add a U oil trap on the outlet of the evaporator.
You can add a little R12 to the refrigerant, it will help oil ruturning.

Also, check that the TEV is not too open, (superheat too low).

Can you give some more details of the chiller?

Chemi

[Superheatman]

Hello everybody,
In chiller with water cooled condenser, compressor oil is collecting into the evaporator. How can we send this oil to the compressor carter? Isthere any solution without changing evaporator?

Thanks for your helps....

Aygul

Hi...is it the case that as oil has collected in the evaporator that someone has been topping up the compressor sump...oil bound evaporator followed by loss of refrigeration effect...loss of suction superheat...I have found that after rectifying the root cause of this type of problem it is reasonably easy to return the oil to the compressor sump where it can be drained to the correct level by running the compressor at full load conditions.There are various reasons to cause oil migration to the evaporator but as other site members have already requested it is necessary to know the details of the unit and a rundown on the present running conditions......best of luck...maybe you could post some details...in any case...the answer is.. no ...you would not have to change the evaporator

[Peter_1]

Is this a new unit and was the problem there since the beginning or is it an old unit which gives just recently problems?
Own design?
Did someone changed something?
Did you serviced always this unit?
Is there a partial load system on the unit?
Enough gas in the system?
Not too high fluctuations in condensing pressure?
What is the superheat?
Furthet the same questions as Marc, shell and tube or plate HE and TEV or flooded?

[aygul]

Thanks all the answers...

evaporator is shell and tube type-refrigerant goes through tubes and water goes outside the tubes. Refrigerant is R22, i thing there is enough refrigerant in the system... there is no unloading... there is screw compressor in the system...
superheat aproximatelly 3 C... tev adjustment is 20 open tours (totally 40 tours)
I thing i increased superheat closing tev...
For oil return problem refrigerant velocity is important, when we increase superheat, can we supply to increase refrigerant velocity? or how much can i add R12 into the system?...

Compressor has oil seperator, can i add additional oil seperator into the system?

[Peter_1]

You're sure the screw has no partial load system (slide on the intake)
You must be sure and not guess if there is enough refrigerant in the system.
What about the answers on the other questions we - Chemi,Tejbir, Marc and I - posed you? We need correct answers and no guesses before we hurther can help you.

A TEV with 20 opening rotations on the spindle doesn't say anything. We need real measured temperature and pressure values.

You have to know what you're doing if you add R12 in the system, there is no rule to determine the quantity.

Adding a second oil separator won't help you if the original one had functioned before very well. Is the present one working fine for the moment?

You see, still too many questions before we can help.

[Superheatman]

Thanks all the answers...

evaporator is shell and tube type-refrigerant goes through tubes and water goes outside the tubes. Refrigerant is R22, i thing there is enough refrigerant in the system... there is no unloading... there is screw compressor in the system...
superheat aproximatelly 3 C... tev adjustment is 20 open tours (totally 40 tours)
I thing i increased superheat closing tev...
For oil return problem refrigerant velocity is important, when we increase superheat, can we supply to increase refrigerant velocity? or how much can i add R12 into the system?...

Compressor has oil seperator, can i add additional oil seperator into the system?

If there is a screw compressor in the system then what type of oil sump and pump is fitted or is there no oil pump at all????..if it was say a Dunham bush horizontal then there are several oil sump and pump configurations.....oil recovery on that type of screw is carried out by adjusting the discharge superheat to a minimum of 18 degrees .....any lower and the oil seperator mesh will not trap entrained oil and you will empty your sump into the system....I have seen 30 gallons of oil dissapear in about one minute due to this problem.......need much more detail yet.....what sort of screw is it etc?????

[chemi-cool]

Yes aygul, go and get all the details. I know its Sunday so first thing tomorow.

Could the present oil saparator is blocked?
Is there a sight glass in the oil returning line?

Chemi