Air Dryer problem

[tvrao161]

Hi,
anybody can pl give me a cause for the following problem.

We have an air dryer (kaeser TI901) was originally running with two compressors of copeland make but they have failed at a time due to the mixup of condensate drain with the refrigerant circuit in its moisture trap & in one of its heat exchanger(two heat exchangers in series).

we removed the refrigerant circuit going into the mosture trap & faulty heat exchanger i.e bypassed. now the connection is directly from Th.Exp.Valve to other heat exchanger.

Installed 1no. Maneurop MTZ64 compressor and started the unit with one heat exchanger in circuit. It has run for few days but again failed the compressor due to its oil has flushed out from compressor(oil remaind in the close circuit).

Kindly suggest what could be the reason for oil going out from the compressor.

Gas -R404a

Regards

[monkey spanners]

If liquid refrigerant returns to the compressor it will evaporate in the oil and make it foam, this will then get pumped out of the compressor with the refrigerant leading to the compressor failing.

You need to check the sizing of the expansion device, the evaporator duty and compressor duty, and also any capacity control and de superheater system (if fitted) that keeps the compressor loaded when there is not much air that needs drying.

[Peter_1]

Like Monkey Spanners said, look at the capacity control system which loads the compressor with discharge gasses at the moments with almost no air flow through the separator.

[The Viking]

The above +
Another thing that causes the oil to migrate from the compressor is a lack of refrigerant.

.

[tvrao161]

thanks for the reply to all.
We will change the txv (from 10ton to 6ton size) that should work for this compressor. yes this unit is fitted with capacity control but it is also not connected in circuit. can u pl explain the de superheater system?

our unit is fitted with accumulator (discharge of compressor is passing thro accumulator & also suction is connected to accum). is this the same de superheater? pl explain its function.
regards

[dorinspeedy]

There is on most air driers an accumulator and a device for evoparate any liquid can enter to compressor same as a sort of accumulator, other have a hot gas bypass, another have a presure switch to control the fan. On Kaeser is probably txv + termocontrol of some kind to turn off the compressor or multipe controls.

[dorinspeedy]

that accumulator is a heat exchanger, the hot gas exiting the compressor heats the mixture of gas-loquid exiting the evaporator tranforming it in gas for enetring in suction of compressor.

[glenn1340]

It seems to me there`s a lot of things on this dryer that are now not standard or out of circuit. I know it`s tempting to carry on changing this, modifying that etc. Wouldn`t it be better to bite the bullet and get the dryer back to its original spec and stop digging a larger hole for yourself?