Suspended Sustance in NH3

[Compressor 12]

I have had the opportunity of being apart of starting a brand new facility built and designed by Ingersoll Rand which we all know is pretty new to the industrial (NH3) refrigeration business. IR has come from a background of Hussman which mainly works with large refrigerators (supermarkets, cosco, ect.).

We have been seeing what could be called normal start-up problems consisting of control issues, liquid pump problems, and debris ect. We have 2 separate systems here Med (50-33F) and Low Temp (-10F) running off the same cond. tower but separate screws (single stage). As of about 3 months ago with near perfect performance before, we have gone through 4 Liquid pump seals on 2 pumps and seeing a very weird substance suspended in our ammonia on the low side. This substance has IR and FES scratching their heads.

After draining the oil pot on the low side Acc. 3 times in a 3 month period (with minimal oil maybe 5gal total) and changing 3 oil filters on the low side screw, we cannot seem to pinpoint or figure out what this substance is. Some factors I believe to be a concern linked to this problems is listed as followed:

1. Location of construction being in farming community and lack of clean pipe during construction
2. Cavitation and cracking of oil in liquid pump
3. Possible use of wrong oil in pump at start-up (I was not employed at that time)

All liquid strainers have been pulled and problems are only found on the low side, either strainer completely clogged or restricted. The substance is found in the pots but not at the amount that we find when we pull the liquid pumps inside the inlet pipe. It seems this substance migrates to the low side and turns the ammonia almost pink in color. In large quantities after sitting and drying it comes to the consistency of powdered hot coco. Very weird.


I have pictures in my photo album of this substance and may be a help in figuring out our problem.

Any feedback would be greatly appreciated.

[Magoo]

Hi Compressor 12.
Sounds like surface rust, have you had sample oil and sediment analyised. A labratory will tell you exactly what it is.
Had similar problem, the oil drained from low side accumulators resembled a orange chocalate colour. Stemmed from pipework sitting around uncapped before installation.
magoo

[Magoo]

Compressor 12.
The next problem will be cleaning up the system. You have already had pump seal failures. Next will be compressor wear and premature re-builds, as it would appear that the whole system is contaminated.
The system recovery/clean-up will be long and expensive for someone.
magoo

[HallsEngineer]

Looks like sand oil and rust mixture. Are you near a sea or sandy area?

[Magoo]

Compressor 12
do you represent the client or the contractor, what ever which way, you will be a long on the site doing clean-up work. Been there done that as per previous. Lots of suction strainer sock replacements and oil changes, oil filter changes, and alot of midnight maintenance work. Do not envey what you have to do to clean up system.
magoo

[mad fridgie]

One has to guess that the liquid pump suction is directly into the bottom of the liquid pot, All contaminents are ending up here. (then into the pump)
Again I must guess that you do not a massive liquid head to pump inlet. Being the case strainers/filters can not be fitted (cavitation problems)
All I can suggest is to change the velocity in the pump feed.
Either by increase the size (diameter)of the of pump feed line (dropper) and take a side feed of for the pump. Or a simple seperation tank as close to the pump inlet
On both the bottom of each vessel or pipe is well below the pump inlet.
Allowing for particulate seperation, without causing pressure drop

[Poodzy]

If this a ammonia system i maybe able to help, we actually had the same type of situation here and we came across are problem because someone wanted to save a buck or two and they did not get certifed nh3 and we ended up with farm grade ammonia that was full of sand, As far as clean up goes drain the system and start over that is what we had to do here. Not sure if this what happened there but looks like the mud we had in the system here. Was 7 years ago and we still have some in the system that shows up every now and then.

[Compressor 12]

Thanks Guys for the Input,

Our area is the southern San Joaquin Valley in central CA. My main guess is the uncapped piping used before the install, and that the oil pot drop leg is too close to the suction to our liquid pumps. The amount of clean-up we have done already has been huge. With the pump seal problems now we are starting to see non-condensibles entering into the system, and our once new energy efficient system is using more and more power.

As far as doing a complete clean-up of the system I doubt we will be allowed the down time to do so. So our PM program just grew leaps and bounds. We have sent oil analysis samples off with no problems but we are looking into a substance analysis lab for further investigation.

Beyond rust and dirt I think there is another factor that may be involved. Has anyone ever heard of the oil in which valve companies coat there valves on the shelves with causing problems when the valves are installed without being completely cleaned? I think that may also be in the system. Just a thought....

The fact of the matter is we are going to be busy...

[Magoo]

Compressor12.
Keep up with regular changes of suction strainer socks, that will ellimnate the fine stuff getting into compressor/s. Consider a decanting/cleanable vessel dragging contaminated liquid out of system at drop leg, vessel with heater that evaporates liquid out, then isolate and clean out trash, repeat repeat till cleared. You will get a lot of mill scale and welding gunge as well. The sand content is going to a huge problem, mostly silicon based, very abbrasive on bearings and seals, can come from blasting vessels after manufacture and not cleaned out correctly.
A big cleanup job.
magoo

[coolcmt]

Hi Compressor 12

Like Magoo says a ammonia cleaner could help you. In Denmark there is a company called Cooling Consult, that has a very good one. Send an e-mail to Per S. Nilsen there. He is an expert when it comes to contaminated ammonia systems. Hope this helps....