05 Ecologically Sound Disposal Methods in Ammonia Technology // Umweltgerechte Entsorgung in der Ammoniak-Technik

Ecologically Sound Disposal Methods in Ammonia Technology

Please note these are German guidelines. You may want to consider them but should be
aware of your country’s regulations.


This paper covers only the materials used in ammonia-based refrigeration plants – i.e.
ammonia as a refrigerant and lubrication oil for various compressors – not the disposal of the plant or its components.


1. Ammonia (NH3)


1.1 Disposal in Cases of Leakage
Ammonia is a natural and environmentally compatible substance.
The binding limit value (BLV) for ammonia is 14 mg/m3 = 20 ppm
(0,7 mg/m3/1 Vppm). When emitting ammonia into the atmosphere, it is prohibited to cause environmental
damage. The ERGP-2 is 150 ppm = 105 mg/m3 (ERGP = Emergency Response
Planning Guidelines). It may therefore be released to the atmosphere.
Ammonia is not listed in the “TA Luft” (German Technical Guidelines on Air Quality
Control).If the concentration in the exhaust air rises above the value approved by the local
authority, the ammonia content must be lowered by water washing the air or by
applying water directly to the leakage site.

In such a case, please note the following:

• Collect the water/ammonia mixture (ammonium hydroxide) in suitable
receptacles or collecting tanks.

• Ammonia shows only a limited reaction with water, as in NH3 + H2O → NH4OH
→ NH4
+ + OH-. This situation causes the solution to undergo alkaline reaction.

• Most of the ammonia is only physically dissolved in the water. Please note the
high vapour pressure of NH3 vs. the vapour pressure of the water.

• Neutralise using hydrochloric acid or diluted sulphuric acid to a pH-value of
between 7 and 8 and dispose of by releasing to the sewer system and its
wastewater treatment plant (consult with plant operator, do not release to
surface water).

• Automate the waste air surface by connecting a gas scrubber with highly
diluted sulphuric acid (< 12 %) as the scrubbing liquid via the installed gas
alarm system. This gas scrubber scrubs and chemically binds the ammonia in
the ambient air. The resultant bond binds the ammonia for good – the
ammonia can no longer escape from the scrubbing fluid. The resultant
compound is completely harmless (artificial fertilizer).
Diluted sulphuric acid = WGK 1 Hazard Category Xi (irritant)

• No installation problems, provided the scrubbing chamber is double walled
with automatic monitoring.

• Properly dispose of the solution, making sure to comply with federal and state
regulations.

1.2 Disposal procedure for plant shutdowns or when reducing the refrigerant
charge

1.2.1 Disposal using Loan Containers
NH3 suppliers may avail themselves of loan containers for disposing of used
ammonia if necessary. These are returned for further commercial utilization.

1.2.2 On-site Combustion of Ammonia
The ammonia awaiting disposal is removed from the refrigeration plant in vapour form
and conducted to the disposal plant using a special high-pressure hose.
After a short warm-up period using propane gas, the disposal plant’s combustion
chamber is brought to a specific operating temperature. A carefully calculated supply
of air and NH3 causes the NH3 to spontaneously combust – without the addition of
propane gas – and then continue to burn in a controlled and calm way. The
temperature of the flame is approx. 700 °C. The main advantage of this type of combustion vs. catalytic combustion is that the
NH3 remains in the flame zone for a very long time and that the NO becomes
unstable at 700 °C and breaks down to nitrogen and oxygen. (2 NO ® N2 + O2 + 180.62 kJ)
The readings showed no nitrosyl compounds.
No C, F, Cl or S compounds are created as no fossil fuels are used to support the
flame. Ammonia is stable at normal temperatures, but when heated the reverse of its
synthesis occurs and it breaks down into its individual elements (92.28 kJ + 2 NH3 «
N2 + 3 H2).

Combustion causes the NH3 to dissociate into water vapour and nitrogen. Therefore,
the waste air from the disposal plant is invisible and odourless.
The H2O initially emerges as vapour and becomes detectable below the dew point.
Advantages:

• The disposal procedure is short, and there are no transport problems.

• The elimination of pressure vessels also eliminates potential risks, as well as the
costs of cleaning the vessels.

• This method allows for emptying the entire cooling system down to a vacuum, and
then refilling it with nitrogen or air.

• This type of disposal is recommended when 800 kg or more ammonia is
being disposed of.

1.2.3 Further Utilization as Ammonium Hydroxide
The waste ammonia is vaporised at ambient temperature. Because of the partial
pressures, the impurities remain in the vaporiser. The pure NH3 is then absorbed in
completely desalted water and processed into ammonium hydroxide (25 % NH3). The
resultant heat is dissipated.

1.2.4 Note:
Federal laws and regulations should be looked into in each case.
eurammon-Information No. 5 / March 2009

2. Ammonia Lubrication Oil
Lubrication oil from NH3 refrigeration plants (mineral oil) is covered by the Ordinance
on Waste Oils (Altölverordnung) § 5a and is thus not a residual material requiring
complex and costly disposal (unlike lubrication oils from other types of refrigerant
plant that don’t use NH3 as refrigerant). Because waste oils from NH3 plants contain neither PCB nor halogens, they fall under
waste code 130205 and may be disposed of as mineral lubricant oils.
NH3-soluble oils (PAG oils) are waste code 130206. Waste oils from NH3 plants may contain between 5 and 7 % ammonia, or even higher
in the case of PAG oils, so it is advisable to evacuate the warm lubrication oil prior to
the oil change and/or observe degasification times before sealing the transport
vessels.


Disposal procedure:

• Pickup by authorized carriers (with a permit to collect or convey wastes pursuant
to § 12 of the AbfG Waste Management Law).

• Hand over the oil to a carrier in exchange for an acceptance certificate.

• Reprocess in an officially licensed reprocessing plant.