How Things Work!
RETA 2012
National Conference
San Antonio, Texas
Long Term Consequences
of Water Contamination in
Closed Loop Anhydrous
Ammonia Refrigeration
Systems
Lawrence F. “TEX” Hildebrand
PSM / RMP Engineer
Wagner-Meinert, LLC
7617 Freedom Way
Fort Wayne, IN 46818
Tel 260 399 2387:
Email thildebrand@wmillc.com
Fax 260 489 7473
Overview of the problem
• In the long term. . . water, in any amount, in
a closed loop ammonia refrigeration system
can have very negative and serious
consequences. The white paper “Long-Term
Consequences of Water Contamination in
Closed
Loop
Anhydrous
Ammonia
Refrigeration Systems” and this presentation
address the negative effects in detail.
Overview of the problem –cont’d
• Water in a closed loop ammonia refrigeration
system is a problem that oftentimes
operators and plant owners are unaware of;
that can result in extremely high penalties to
be paid both in the immediate expense of
operating their refrigeration systems in a
contaminated condition and in the long-term
deterioration of the refrigeration system
itself.
WHAT IS ANYHDROUS
AMMONIA?
• Closed loop vapor compression ammonia
refrigeration systems are designed to utilize
Anhydrous Ammonia (NH3) as the
refrigerant. Anhydrous is an adjective
which is used to describe a substance or
compound that contains no water! All
design criteria, manufacturer’s equipment
rating data, service information etc.
published on this subject by equipment
manufacturers is based on this fact.
WHAT IS ANYHDROUS
AMMONIA? –cont’d
• When water is added to, or is allowed to
mix with, the ammonia refrigerant, the
composition of the substance changes and
it is no longer Anhydrous Ammonia (NH3),
but changes to Ammonium Hydroxide
(NH4+OH-) and this new substance is most
often referred to as aqueous ammonia.
Proper Specification
• The proper specification for Anhydrous
Ammonia for closed loop ammonia
refrigeration systems contains at least
99.995 percent ammonia, allowing only
33PPM maximum water, and a maximum of
2 PPM oil as impurities. This does not
include any appreciable room for air or
oxygen as a contaminant.
Allowable Water Content
•After all relevant sources, scenarios, and
consequences have been considered, the
ONLY correct choice, the one that is
recommended by IIAR, and which is in
agreement with the OSHA specification, for
closed loop ammonia refrigeration systems is
“P” Premium grade (AKA
“REFRIGERATION” grade) anhydrous
ammonia.
http://www.osha.gov/SLTC/etools/ammonia_refrigeration/am
monia/
Best Possible Heat Transfer
• The cleanliness of the refrigerant is the key
to getting the best heat transfer coefficient,
least operating cost, most effective use of
installed suction capacity of compressors,
and longest mean time to failure for the
operation of the industrial ammonia-based
refrigeration systems.
Detriments of Water
•Water in a closed loop ammonia
refrigeration system is enemy number 1 to
the proper operation of the refrigeration
system. Its presence in the refrigeration
system precipitates the degrading of
performance, capacity, cost of operation,
and mean time to failure of the associated
equipment.
Likelihood of Water in Your System
•Water contamination in ammonia refrigeration
systems is quite common, but mostly unrecognized. *A recent survey of ammonia
refrigerant plants was made in Denmark, Norway,
and Sweden. This survey covered some 136
individual refrigeration plants. The results clearly
indicated that water contamination of 2% to 6%
was quite common. Less common, plants
showed water contamination levels of 10%, 18%,
24% and 26%.
*Per Skaerbek Nielsen , Mech. Engineer Danfoss, “Effects of Water Contamination in
Ammonia Refrigeration Systems” Copyright Danfoss A/S, Denmark– November , 2000.
Likelihood of Water in Your System
Until water boil test procedures are
implemented and regularly carried out as a
part of regular maintenance inspection
procedures for Anhydrous Ammonia
Refrigeration Systems, the general
assumption will remain that water is not a
problem. Yet, as the referenced article
clearly spells out, the overwhelming majority
of plants surveyed proved to have
significant amounts of water.
Unrecognized Danger
• Water contamination in ammonia refrigeration
systems is much more common than most
owners / operators realize and the ignorance of
these facts does not keep the damage from
occurring in your specific plant. The damage
caused by its presence takes time to show
directly, because it takes time to ravish a
refrigeration system with the tragic reality. It is
mostly not recognized in the early stages when
mitigation would be much less costly than repair
and replacement after the damage has occurred.
Why be concerned with water contamination
in the ammonia refrigerant?
• Loss of refrigeration capacity requiring the lowering of
suction pressures to meet load conditions.
• Increase in horsepower to operate the system at required
temperatures.
• Increase in compressor suction volume due to handling
higher cubic feet per pound at for same evaporating
temperature.
• Increased energy consumption for same evaporating
temperature.
• Increased mass flow rate to evaporators required due to
volume occupied by water in mixture.
• Increase in discharge temperature of the compressors.
General causes & effects as it concerns the
refrigeration system & components.
• Emulsification of tramp oil throughout the refrigeration
system.
• Increase in component failure due to acids.
• Erosion of any component that is throttling liquid.
• Increase in maintenance required; i.e. clogging strainers,
regulators sticking, etc.
• Color of the oil drained from the oil pots.
• Sight glasses that you can’t see through because they are
coated with scum on the inside.
• Deterioration of compressor oil.
• Malfunctioning of thermal expansion valves.
Increased maintenance budget and unexpected
(unplanned) expenses that have to be met.
• Cost of increased energy consumption.
• Cost of increased use of repair parts and consumables.
• Cost of increased to stock additional repair parts necessary
to cover emergency shut down situations.
• Cost of increased (unplanned) maintenance man hours
spent.
• Need to re-adjust work schedule; vacations, time off, etc.
• Cost of increased down time of critical operational
processes, including re-scheduling production or needing
to schedule overtime to make up for lack of normal
production capacity.
Keeping Anhydrous Ammonia Pure!
• The best way to escape the necessity of dealing
with the entire composite list of the budgetary
issues discussed in the previous section is to
KEEP YOUR AMMONIA REFRIGERANT
ANHYDROUS. In plain English “Keep the water
out!” If, after the boil out tests previously
recommended are carried out, the evidence shows
a higher than acceptable level of water, set in
motion a constructive plan of action to remove the
contamination from your refrigeration system and
restore it to the health and performance of
Anhydrous (Refrigeration) grade ammonia.
Keeping Anhydrous Ammonia Pure!
• If the refrigeration system is not already
so equipped, it is strongly suggested
that a liquid filtration system should be
installed in the liquid line outlet of the
high pressure receiver (HPR), or
controlled pressure receiver (CPR) that
will remove any solids in the liquid
stream at a particle size of 0.5 micron
or larger.
Keeping Anhydrous Ammonia Pure!
• When making a selection of a liquid
filtration system it is necessary to
carefully investigate to ensure that all
the components of this filtration system
are totally compatible with the
ammonia refrigeration system. Note:
Only particulate matter can be
removed.
Keeping Anhydrous Ammonia Pure!
• There is not, at present, any
absorbent or adsorbent type filter
cartridge that will remove water
from the ammonia. Be very careful
NOT to install halocarbon type
cartridges in “an ammonia
refrigeration system”.
Keeping Anhydrous Ammonia Pure!
• The bonding cement used in the
manufacture of this type of
cartridge will immediately be
destroyed by the liquid ammonia
and the result would be brown or
black particulate matter from such
a cartridge scattered throughout
the ammonia system.
Keeping Anhydrous Ammonia Pure!
• Be fore-warned; the clean up after
such an event will be costly and
quite time consuming, even
requiring possible plant shutdowns
to accomplish.
How can water be removed from the
Ammonia Refrigeration System?
• When water or water vapor enters,
by whatever means, into the
pressure envelope of the closed
loop anhydrous ammonia
refrigeration system it immediately
combines with the anhydrous
ammonia to form an aqua
ammonia mixture, aka ammonium
hydroxide (HN4+OH-).
How can water be removed from the
Ammonia Refrigeration System?
• Once this mixture is formed,
the water component can
only be removed through a
process of distillation.
How can water be removed from the
Ammonia Refrigeration System?
• That is to say, the mixture must be
caused to boil at a low enough
temperature so that the ammonia
component will leave the boiling pool
as essentially pure ammonia vapor and
the remainder will be a highly
concentrated mixture of water with a
low percent of ammonia still in the
mixture.
How can water be removed from the
Ammonia Refrigeration System?
• Be advised, however, time is of the
essence to stop the ancillary damage
that will be caused by the by-products
of this contamination. The sludge,
acids, particulate matter, etc. all are
multiplied and compounded by the
amount of time in which the
contamination continues.
How can water be removed from the
Ammonia Refrigeration System?
• Once these contamination processes
have started, even taking all of the
water out may not completely stop the
degradation of the refrigeration system
completely without further remediation
requirements.
How can water be removed from the
Ammonia Refrigeration System?
• On severely contaminated systems that
have been allowed to remain in that
condition for a long period of time it
may be necessary to use a flushing
solution mixed into the ammonia liquid
to slowly restore the internal
cleanliness of the refrigeration system.
How can water be removed from the
Ammonia Refrigeration System?
I.
A number of commercial distilling
packages are available. Any one of
these; dehydrator, anhydrator, or
whatever else the package may be
named, will produce a stream of
essentially pure ammonia vapor plus
a separate stream of mixture of
water with approximately 28%
ammonia still in the mixture.
How can water be removed from the
Ammonia Refrigeration System?
II.
The Dump and replace the charge
method.
Oftentimes, when it is first discovered
that there is a significant amount of water
contamination in the refrigeration system,
the concept that simply replacing the
charge of ammonia will solve the problem
appears to be the easiest way to
remediate the problem.
How can water be removed from the
Ammonia Refrigeration System?
II.
The Dump and replace the charge
method.
This may be a viable solution, but
oftentimes when this approach is carried
out, the water contamination levels
previously measured quickly seem to
return to levels close to the contamination
recorded prior to undertaking the clean
up procedure.
How can water be removed from the
Ammonia Refrigeration System?
II.
The Dump and replace the charge
method.
The problem is that most piping systems,
as installed, have many low spots without
adequate provision for gravity draining
the contaminated mixture from the
system completely.
How can water be removed from the
Ammonia Refrigeration System?
II.
The Dump and replace the charge
method.
Thus, the evacuation procedure
must be relied on to boil out the
remaining contaminated ammonia
and water.
How can water be removed from the
Ammonia Refrigeration System?
II.
The Dump and replace the charge
method.
Unless sufficient time, utilizing a vacuum pump
of correct cfm capacity with the capability of
deep vacuum suction capacity is employed,
coupled with a heated nitrogen gas sweep to
thoroughly cleanse the entire system, this
method will turn out to be less than expected in
successfulness.
How can water be removed from the
Ammonia Refrigeration System?
II.
The Dump and replace the charge
method.
In a short time frame, the hidden
water will show up in its usual haunts
and the system remains
contaminated.
How can water be removed from the
Ammonia Refrigeration System?
II.
The Dump and replace the charge
method.
This may be a practical solution if the
water contamination is confined to only a
local area of the ammonia refrigeration
plant (i.e. to clean up after rupture of a
secondary fluid heat exchanger after a
repair has been made).
How can water be removed from the
Ammonia Refrigeration System?
II.
The Dump and replace the charge
method.
Dumping and re-charging the high side
vessel(s) should only be considered if
there was a recent leak causing
significant contamination levels of water
contamination in the high side.
Options for applying a distillation
process
I.
Hire an outside service contractor to do a
complete plant clean up in a relatively short
period of time.
II. Rent and install temporarily a large system
to clean up the entire system in a relatively
short period of time, then consider a
permanent solution.
III. Purchase, and install permanently, a
traditional Still or Remediator to remove
water from the refrigeration system.
Options for applying a distillation
process
IV.
Purchase, and install permanently, a small
automatic Still that provides for continuous,
safe, and automatic water & oil removal.
Careful consideration should be given to this
system as perhaps the most synergistic
approach to the good health of your ammonia
refrigeration plant.
Consider this as a preventative measure,
similar to an auto purger to prevent major
contamination from occurring in the first place.
Effect of water contamination in
Ammonia Refrigeration System
• The following 2 slides show graphs
indicating the degradation of suction
volume and increase in energy
required to operate the refrigeration
system when water contamination is
present in the refrigerant.
• For more detailed breakdown of
effects see Case Study, chapter 13 of
the Paper.
Photos of damage to components
on water contaminated systems
The photos in the following slides are
from a number of contaminated
systems which necessitated clean up
methods.
PHILLIPS 701 Pilot Valve Parts (1)
New Parts
Damaged Parts







44
PHILLIPS 701 Pilot Valve Parts (1)
45
PHILLIPS 701 Pilot Valve Parts (2)
46
Strainer basket
New
for comparison
Old
From -40 Deg. F. Liquid Makeup
from Controlled Pressure
Receiver

47
Strainer basket
48
Strainer basket
49
Liquid Line Shut-off Valve
50
TXV Cage Assembly
New
Used (1)


51
Damaged TXV Cage
Assembly

Used (1)
Used (1)

52
Damaged Phillips Pilot Float Valve Cartridge
Used



53

Damage on In-Line Check
Valve Parts




54
Preventative Maintenance
 Ensure that an ammonia still is
installed and is functioning properly.
 Utilize System Opening Policy (Line
Breaking Permit Procedure).
 Perform periodic inspections for
negative pressure leaks (shaft seals,
valve stems, etc.)
55
Preventative Maintenance (Cont’d).
 In plants where CO2 is used in the
process, special care should be
placed on proper ventilation systems
to preclude the CO2 concentration
from entering the Refrigeration
System, through possible vacuum
leaks or during service/maintenance
operations.
56
Preventative Maintenance (Cont’d).
 Regular oil samples from all
compressors should be analyzed for
water, particle count, wear debris,
Total Acid Number (TAN), and
properties of the lubricant, i.e.
viscosity, additive depletion, etc.
Trend charts for monitoring change
are useful.
57
Preventative Maintenance (Cont’d).
 Oil sample from new oil (to establish
baseline) should be included with
compressor oil samples.
 Periodic samples from oil in oil pots
should be sent to lab for analysis to
determine Total Acid Number (TAN),
water content, and particle count.
58
Wrap up
Any questions?
Wrap up
Thank you all for
attending!