PDA

View Full Version : NH3 Compressor with RWB II Plus control panel problem







angyoshin
19-10-2011, 09:20 AM
Hi every one

I have problem with my NH3 system. Problem is when NH3 compressor run full load (I mean slide valve > 90% and motor FLA > 90) suction temp, oil temp and sep temp value is very swing and NH3 compressor stop without any error message. If compressor run with slide valve < 90% it can work very well.

Any one have my same problem ?

Thank you.

Grizzly
19-10-2011, 05:58 PM
Just a guess, but has anyone or anything altered the working levels?
You just may be starving the compressor or cavitateing the pump.
When approaching 90% Slide value observe working levels, Comp operating pressures etc.
Also check the pressure differential across pump. Is there a diff pressure switch on the Liquid pump/s?
Does your control software not have a diagnosis page or digital input history you can interrogate?
Logically your comp may not be at fault just an unbalance in the system.
A bit of logical detective work may solve your issue.
Maybe, You may find out more by manually loading system to near 90% and checking what's happening elsewhere.
Good luck Grizzly

angyoshin
25-10-2011, 10:26 AM
Thank you Grizzly
I try to change every thing my control panel but still have problem.
I think my problem is noise because I test by remove oil temp sensor to measure ambient temp by control panel

RANGER1
25-10-2011, 10:59 AM
Thank you Grizzly
I try to change every thing my control panel but still have problem.
I think my problem is noise because I test by remove oil temp sensor to measure ambient temp by control panel

angyoshin,


Have you checked/changed power supply in panel.
If playing up can cause crazy things to happen.

angyoshin
25-10-2011, 11:01 AM
Where possible noise come from?
Thank you.

angyoshin
25-10-2011, 11:03 AM
i changed power supply already.

angyoshin
26-10-2011, 02:28 AM
I saw something in screw compressor manual.
" The major contributor to noise is usually not directly attributable to the compressor, and most of the
noise is likely to be generated by the oil separator, the discharge line, and the motor. These components generate noise primarily because of the pulsations of flow which are characteristic of the screw compressor. Noise generation increases when there is under- or over compression "
I already changed motor. what i should to do with oil sep and discharge line ?

angyoshin
26-10-2011, 02:28 AM
I saw something in screw compressor manual.
" The major contributor to noise is usually not directly attributable to the compressor, and most of the
noise is likely to be generated by the oil separator, the discharge line, and the motor. These components generate noise primarily because of the pulsations of flow which are characteristic of the screw compressor. Noise generation increases when there is under- or over compression "
I already changed motor. what i should to do with oil sep and discharge line ?

RANGER1
26-10-2011, 10:07 AM
angyoshin,
Do your sensors have screened cable & is it earthed correctly?

The compressor should not have over/under compression if RWB calibrated & working OK.

When was compressor last major service, maybe noise is generated from compressor.

angyoshin
26-10-2011, 10:40 AM
RANGER1,
Earthed cable of sensor is correct. Before this problem, The motor compressor was burst. After I change motor noise problem was happen.

RANGER1
26-10-2011, 09:23 PM
angyoshin

Coupling & alignment might be one issue, damaged compressor the other.

Was there a particular reason why motor blew up?

Can you give all pressure/temp readings when compressor is running.?

Is the noise there all the time now, or when compressor reaches a certain load?

angyoshin
27-10-2011, 05:53 AM
RANGER1

I test run compressor 2 time.

No.1 Setpoint suction pressure = 3.6 bar

Time Suct.Press. Suct.Temp. Disc.Press. Disc.Temp. Oil Press. Oil Temp. Sep.Temp. Slide Valve
Start 3.81 bar 25 C 5.5 bar 66 C 5.86 46 76 0 %
2 min. 3.66 16 11.85 62 11.10 42 47 55 %
4 min. 3.66 12 11.79 76 11.03 53 64 65
10 min. 3.65 0 11.72 78 11.16 52 77 85
12 min. 3.64 -3 11.72 77 11.16 50 78 85

It work can run over 1 hour without shutdown.

No.2 Setpoint suction pressure = 3.5 bar

Time Suct.Press. Suct.Temp. Disc.Press. Disc.Temp. Oil Press. Oil Temp. Sep.Temp. Slide Valve
1 min. 3.68 5 11.85 71 11.03 47 74 65
2 min. 3.65 0 11.85 75 11.03 50 74 75
4 min. 3.68 -3 11.99 72 11.37 46 74 90

at 4 min. noise is coming, All temp sensor value is swing, and compressor shutdown.

RANGER1
27-10-2011, 10:35 AM
angyoshin,
Its not plainly obvious but it looks probable that liquid ammonia is entering compressor, especially when loaded up quicker in set pont 2.
The oil & discharge temp drops 4 C
The liquid ammonia in a slug entering compressor can sound pretty bad in some cases if large enough.

I think check out levels in evaporator.

What type of evaporator is it & how are levels controlled?

Common causes can be oil in float or probe control column giving false levels, or leaking liquid makeup valve.

Isolate this liquid makeup on suction accumulator if possible & resume some tests.

Magoo
28-10-2011, 03:26 AM
Angyoshin,
may not be relevent, but had a similar problem on a RWB 11 plus, stopped at full load and no indication. Eventually problem sorted out, it was one of the CT coils on incoming power to system that went crazy at full load., created a supply imbalance and tripped the system out.