High Discharge temperature Mycom 200 VLD 5.8 fwith economizer .. Hi everybody

[sicisici]

Hi everybody, i'm having problem with my compressor , for discharge temperature above 80 °C . the ampere absorbtion is ok and discharge pression is less 13 bar .
How could i fix this error?1421914216142171421814215

[RANGER1]

sicisci,
Can you tell us a bit more like
- refrigerant
- suction & discharge pressures
- oil pressure above discharge pressure or nett oil pressure.
- oil temperature
- how oil is cooled, water or thermosyphon oil cooling.
- oil injection, does it have a valve in oil line, line connects into rotor housing half
way along on drive side of compressor.
- What is compressor cooling, freezer of some kind?

Maximum discharge temperature is 90 deg C & not uncommon for discharge temperature to be around 80-85 deg C


If you had -33 deg C sst & +37 deg C sct theoretical discharge temperature would be 80.8 Deg C with 50 deg C oil temperature

[cduque]

In screw compressors the discharge temperature is maintained around 80ºC with the oil cooling.
If you're having problems with high discharge temperature the problem might be in your oil cooling system or in the oil flow (filters?). Check it out.

[sicisici]

in that compressor i have ammonia, and a ammonia thermosifon to cool oil without oil valve and a economizer.
Last week i had oil temperature oil and i fixed that problem putting:
economizer start at 90% from 95% and economizer stop at 80% from 80% and added same oil in the compressor!
Now I'm having problem with discharge temperature , about 84 °C with alarm at 80 °C.

[Josip]

Hi, sicisici :)

welcome to RE forums...


in that compressor i have ammonia, and a ammonia thermosifon to cool oil without oil valve and a economizer.
Last week i had oil temperature oil and i fixed that problem putting:
economizer start at 90% from 95% and economizer stop at 80% from 80% and added same oil in the compressor!
Now I'm having problem with discharge temperature , about 84 °C with alarm at 80 °C.

to be able to help you we need some info about your system otherwise this guessing can last forever ;)

... there are some questions from RANGER1 still not answered ...

Assuming your compressor is running in one stage ... within evaporating/suction pressure about -35*C and condensing pressure about +35*C ... maybe ice-cream production!?!

economizer is probably there to sub-cool liquid for low temp. heat exchanger..

and until now no problem with your system ... right?

can you tell us what happened or what you changed within system and after that you have some higher discharge temperature ...


This one is not clear to me :

Last week i had oil temperature oil and i fixed that problem putting: economizer start at 90% from 95% and economizer stop at 80% from 80% and added same oil in the compressor!
can you, please, explain those numbers and start&stop of economizer in some simple way....

... why you add some oil ...?


Then if you can give us data about:

1. suction temperature
2. suction super-heat

*****************************************
3.discharge temperature ... is about 84*C
4. discharge super-heat is about 48K..
5. discharge pressure is equal or less then 13 barg .. saturated temp is about (T=36,3*C)
******************************************

6. inlet oil temperature or oil temperature after oil cooler

... if you can read those data from your compressor controller or some other control panel

7. Type of ammonia condenser

Do you have some other compressor/s in the same circuit?



Sorry, but to be able to help you we need as much as possible info about plant ...

Best regards, Josip :)

[sicisici]

Here you are compressor monitor photo, is in italian ,and i suppose you could understand,

[RANGER1]

Sorry cannot see monitor

[RANGER1]

sicisici,
Oil pressure looks a bit low to me, as it's below 2bar.
Can you let us know what your recommended oil pressure is.
I would suggest 2.5bar

Discharge pressure is a bit high as well, check condensers working correctly, fans & water sprays.
Also check for air in system, does it have auto air purger?

Maybe clean all oil filters first.

Alarm of 80 deg C seem to low, should be 85 deg C alarm & 90 deg C trip point

Also check oil injection line cooling compressor, which is oil line connected to drive rotor side.
Is it oil from oil pump or inlet or outlet?

[sicisici]

Thanks so much.... oil from pump...i suppose..i'll make you another photo

[sicisici]

[QUOTE=jave a look about oil pump and piping

[RANGER1]

[QUOTE=jave a look about oil pump and piping

sicisici,
From what I can see red capped valve is oil injection valve supplying cooling to compressor.
How far open is this valve, check, as could be open a least 3 to 4 turns, maybe even more

Have you cleaned oil filters & increased oil pressure, purged air from system?

[Magoo]

Totally agree with Ranger 1 , high discharge temperature problems are directly related to oil flow rates and oil injection temperatures.
If you have a filter screen not a filter. Between oil separator and oil pump, check that is super clean.

[Tycho]

you said earlier that you added oil to the compressor, so this must mean that the level was low?

You should also check if there is an oil build up on the NH3 side of the oil cooler.

A good way to find out if you have oil collecting on the wrong side of the oil cooler is to run your hand from the top and down to the bottom of the outside shell on the oil cooler.

If there is oil, the ammonia will be on top, so the top will be "cool" to the touch, but the oil will be almost the same temperature as the oil in the compressor, so you should notice a distinct temperature difference on the shell if oil has collected on the NH3 side of the oil cooler.