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charlie n
09-01-2014, 08:56 PM
Does anyone have any advise or instructions for cleanup of a cascade system that had a leak in the CO2/ammonia cascade condenser? The compressors are trashed (100+ TR Screws). I'm looking for what to do with the pipes before installing new compressors.

RANGER1
10-01-2014, 09:26 PM
Someone may correct me, but I'm thinking water or warm water on NH3 side only.

Ammonium carbamate is extremely soluble in water.

Suggest contact ammonia/CO2 supplier for exact details & any precautions with clean up.

Obviously pipe lines would have to be dried out as best as possible, draining water from low points etc.

Any residue left will block strainers & have to be cleaned.

Superfridge
12-01-2014, 08:06 AM
Hey Charlie N,
I have been thinking about posting a question regarding this exact situation for some time as there are a few NH3/CO2 systems about. I'm no help but please keep us up to date with the situation and good luck.

cricri
12-01-2014, 01:30 PM
Hi Charlie N,
we got similar issue 2 years ago, 5 t CO2 went accross 500kg ammonia after a condenser failure. CO2 went 11093out through the relief valves on LP. there was about 1 cm of carbamate all around the wall of LP vessel and pipes.
We filled up the ammonia plant of hot water (air has to be purged to make sure theat all pipes are completely filled) warmed by a 35kw electric heater to 70C and a put in circulation by a pump. every pipe was connected to the water system and cleaned, many connections with ball valves and quick coupling done.
we changed the water added with dispersant agent 3 times to get it clean, we checked the Ph target 7 before a water change. and the last time we added a sludge remover. water was retreated as it became Urea.
after that we purged water and dryed it with an air dryer (ie Munters).oil separator was cleaned separatly following same procedure.
compressor full of carbamate overaulled and reused.
after more than one year everything is going fine; oil analysis are OK for water contamination and other contaminants.
an other company at the same issue and cleaned the system with air warmed up to 70C. I have no information about the result. sublimation carbamate produces solid residues...
What is your brand of heat exchanger?
good luck, it's a hard work which took us about 3 month, we were not in a hurry, the plant was still running on MEG condensers and rental refrigeration units .
regards

charlie n
26-01-2014, 07:29 PM
We removed all internals from ICF valves and blanked the holes then we introduced steam inside everything. Not finished yet but it looks like it will work. Be careful, we overheated the Evap. condensers and damaged the plastic spray pipes & moisture eliminators. Valve internals are rusty. we will try cleaning them and re-installing but we're keeping spares on hand just in case. Many thanks for the suggestions. Will keep you posted.

mbc
28-02-2014, 03:52 PM
look co2 boils at -78 c and NH3 boils at-33 c
only you need to warm up all pipes both goes away if you are in hurry or you can not to heated you could use hot air inside pipe or N2 .

dvtruc
29-04-2014, 10:17 AM
Charlie n,

What kind and make of your CO2 condenser, the leak and new one. To avoid such problem, a double wall PHE or double tubesheet should be used.

Truc