copyright wmi/l. f. 'tex' hildebrand 02/2003 1 acid problems in ammonia refrigeration...

Copyright WMI/L. F. 'TEX' Hildebrand 02/2003

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Acid problems inAmmonia Refrigeration Systems

Presented at:

IIAR 2003 Ammonia Refrigeration Conference & Exhibition,

Albuquerque, New Mexico


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Presented by:

L. F. “Tex” Hildebrand


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IIAR Bulletin 108– Water in Ammonia causes

•loss of capacity•Increase of horsepower•“Chemical changes to compressor

oil. . .’–Organic acids–Sludges–etc.


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Water, if left unchecked, in an ammonia refrigeration plant will result in:

– Contamination,– Sludge, and– Corrosion damage to

components


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Symptoms of contamination Strainers clogging. Corrosion failure to float valve

cartridges, solenoid valves, thermal expansion valves, check valves, etc. (wherever liquid is throttled).

Sight glasses coated from inside with a brown emulsion (gooey stuff!).

Problems maintaining evaporating temperatures.


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Causes of contamination - Let us look at The Players and their roles:

• AMMONIA• COMPRESSOR• OIL• AIR• WATER• CO2

• DISSOCIATION BY-PRODUCTS• SLUDGE (BECOMES THE “MAALOX”)• ANAEROBIC BACTERIA• ORGANIC ACID(S)


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Remedies – The actual remedy applied will vary

with the extent of contamination found in the system. Generally the following class conditions will apply:1. When contamination is discovered at

an early stage2. When contamination has progressed

to a more serious state3. A very seriously contaminated system


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Remedies (Class Condition-1). NOTE: This remedy should be used in conjunction to all others.– Install an ammonia still to remove

the water and stop the contamination from progressing.

– Liquid filters in pumped liquid lines will help clean up the contamination. (However, if water is not removed, contamination will continue to grow).


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Remedies (Class Condition-2).– Shut down system and remove all

ammonia charge.– De-hydrate entire system with

appropriate evacuation – Re-charge system with

refrigeration grade ammonia.– Insure proper ventilation if CO2 is

in use in plant processes.


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Remedies (Class Condition-3).– Shut down system and remove all

ammonia charge.– Using an appropriate mixture of

solvents, clean all vessels, and piping, if possible.

– Clean or replace all sight glasses, strainers, throttling device kits.

– Repair or replace all check valves.


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Remedies (Class Condition-3 Cont’d).– Change oil and filters on all

compressors.– Dehydrate entire system with

appropriate evacuation.– Re-charge system with

REFRIGERATION GRADE AMMONIA.


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PHILLIPS 701 Pilot Valve Parts (1)

New Parts Damaged Parts


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Strainer basket

OldFrom -40 Deg. F. Liquid Makeup from Controlled Pressure Receiver

Newfor comparison


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TXV Cage Assembly

New

Used (1)


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Damaged TXV Cage Assembly

Used (2)

Used (1) Example of brown emulsion (gooey stuff!)


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Used (1)

Used (1)


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Used (2)

Used (2)


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Damaged Phillips Pilot Float Valve Cartridge

Used


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Damage on In-Line Check Valve Parts


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Preventative Maintenance Insure that ammonia still is

installed and is functioning properly.

System Opening Policy (Line Breaking Permit Procedure).

Periodic inspections for negative pressure leaks (shaft seals, valve stems, etc.)


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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.


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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.


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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, and particle count.


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Oil samples should always be collected adhering to a written oil sample procedure to insure accuracy and repeatability.

Periodic tests should be performed according to IIAR Bulletin 108.

Install filter in liquid ammonia lines.


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Summary Water seriously damages the

lubricating properties of oil and promotes component corrosion. Increased water concentrations indicate possible condensation, coolant leaks, or process leaks around the seals. Improper maintenance procedures may also contribute to this problem.


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Summary (Cont’d) Organic acids, a by-product of oil

oxidation, degrade oil properties and lead to corrosion of the internal components.

The Total Acid Number (TAN) is lowest as a virgin oil and can gradually increase with use.


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Summary (Cont’d) A steady rise in the Total Acid

Number (TAN) is an alarm for an oil change.

Increase in acid levels is typically caused by oil oxidation over time. However, acids generated due to contamination by-products will send the Total Acid Number (TAN) soaring in a relatively short time span.


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Summary (Cont’d)•The invasion of contaminants from

the surrounding environment in the form of dirt, water, and process contamination are the leading cause of machine degradation and failure. Monitoring increased contamination should be the trigger to take action in order to save the oil and avoid unnecessary machine wear.


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Summary (Cont’d)•By identifying potential sources of

contamination, it is possible to more effectively monitor the level of contaminants in the lubricating oils. Potential contaminants and sources of ingression will be identified. This will allow for proper monitoring, and specific corrective action when contamination is found.


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Elements Possible Source Elements Possible Source

I ron (Fe)Shafts, Gears,Housing, PistonRings, Cylinder Walls

Silicon (Si)Dirt, DefoamantAdditive

Copper (Cu)Brass/ Bronze Alloys,Bearings, Bushings,Thrust Washers

Boron (B)Anti-corrosion inCoolants

Lead (Pb)Bearings, Anti-WearGears

Sodium (Na)Detergent Additive,Coolant Additive

Tin (Sn)Bearing Alloys,Bearing Cages,Solder

Barium (Ba)Rust and CorrosionInhibitors

Aluminum(Al)

Pumps, ThrustWashers, Pistons

Calcium (Ca)Detergent/ DispersantAdditive

Chromium(Cr)

Roller Bearings,Piston Rings,Cylinder Walls

Phosphorus(P)

Anti-wear Additive, EPGear Additive

Nickel (Ni)Pumps, GearPlatings, Valves

Potassium (K) Coolant Additive

Titanium (Ti) Exotic AlloyMolybdenum(Mo)

EP Additive

Silver (Ag) Some Bearings Zinc (Zn) Anti-wear Additive

Magnesium(Mg)

Detergent Additive,Coolant Additive

Vanadium (V) Turbine Blades

Identification of elements in particulate matter


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Questions?


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Thank You!“Tex”

copyright wmi/l. f. 'tex' hildebrand 02/2003 1 acid problems in ammonia refrigeration...

Documents

tex hildebrand slide

copyright wmil

refrigeration grade

ammonia refrigeration

acid problems

ammonia charge

comparison slide

contaminated system