Recovery/online
ammonia decontamination technology helps processors realize
increased productivity.
Because
chloroflourocarbons (CFCs) are becoming increasingly regulated and
CFCs and hydrochloroflourocarbons (HCFCs) are being phased out, using
ammonia as an alternative refrigerant is gaining popularity. While
ammonia systems are a successful substitute in many manufacturing
environments, contamination problems exist that reduce efficiency,
increase energy use and can lead to catastrophic damage resulting in
line shutdown. Recent technological developments can predict
contamination problems such as moisture, oil and particulate.
Because ammonia and water have a great affinity for each
other, water in the refrigerant side of an ammonia chiller can create
serious problems. It mixes with the lubricating oil and forms organic
acids that can damage the cooling system. By changing the ammonia from
an anhydrous to an aqueous ammonia solution, water degrades chiller
efficiency as power use ramps up.
Moisture can enter an ammonia chiller in several ways.
The most common include ruptures; joint, seal, packing and valve
leakage; and condensation during installation. When water enters the
ammonia side of a chiller it:
• Increase refrigerant temperature.
• Decreases pump performance, piping pressure and evaporator
efficiency.
• Increases energy costs.
• Forms explosive or unstable compounds.
Mineral-
and paraffin-based oils in an ammonia system can:
• Leech into the ammonia side from
the discharge side of the compressor.
• Travel through the condenser and receiver to settle in the the
evaporator.
• Oil log the evaporator, thereby significantly reducing system
efficiency.
When particulate such as rust, metal particles or dirt contaminate a
chiller, they cause serious damage, including premature wear; clogged
restrictions, metering devices, oil lines and filters; and reduced
efficiency.
To address these problems, processors can use a
refrigerant-side decontamination system. It recovers refrigerant at
high speeds and simultaneously decontaminates it.
The system works by recovering ammonia when a system is
down for repairs. The system recovers and stores refrigerant in the
proper cylinders, then decontaminates it on-site so it can be used to
recharge the system. This can be particularly important to a plant's
toxicity reduction inventory.
Two examples can show how this recover/reclamation system
works.
Example. A vitamin manufacturer had a process chiller
that was scheduled for repairs, but it was having trouble finding a
company willing to perform the refrigerant recovery. This two-tiered
system used simple refrigerant-grade ammonia on on side and special
process ammonia, which contained acetylene, hexane and potassium
hydroxide on the other. Because ammonia reacts negatively with many
chemicals and attacks anything made of copper, the refrigerant was
difficult to recover, making the process mixture even more volatile.
Using its recovery system, special hoses and safety gear, recovery
system personnel connected to the process chiller. A day and half
later, 20,000 lb of ammonia had been recovered and stored to await
reinstallation. "That was impressive to watch," said the
vitamin plant manager. "The ammonia was recovered faster than we
expected. Days were cut off the repair time, and a small fortune was
saved in lost production."
Recovery/reclamation technology also provides increased
uptime. Ammonia-side services use the system to remove water, oil and
particulate from a refrigeration system while it continues to operate.
While the ammonia replacement cost is low, the downtime
needed to recover the old ammonia and replace it with the new can can
be prohibitive. The recovery/reclamation system can be used to
decontaminate old ammonia that is warehoused for disposal, allowing it
to be used again. This significantly reduces the net weight of
materials to be disposed.
Another example. An 8,000 gal liquid overfeed system used
to manufacture latex rubber was performing significantly below
capacity. The service contractor discovered a large amount of water in
the refrigerant. The standard method for returning the system to peak
efficiency would have been to shut down the line, recover the
contaminated refrigerant and replace it with new. If the leak was
slow, it could be identified and repaired during the scheduled
maintenance shutdown. But, the downtime could cost the plant hundreds
of thousands of dollars a day in lost production.
Instead, the decontamination system, primed with ammonia,
was connected to the chiller and provided high volume distillation. As
the refrigerant passed through the system, moisture was removed as
well as particulate and excess lubricating oil. In a matter of 10
days, more than 1,000 gal of water had been removed and the chiller
returned to peak efficiency. PCE
For more information
Call (845) 735-6000