Transcript r22 polution of r717 refrigeration plants

R22 polution of R717 refrigeration systems
• How can it happen?
• How do R22 and R717 react in the system?
• What will be the “symptoms” on the system?
• How do we solve the problem if R22 gets into a R717 system?
• How do we avoid R22 gets into the system?
CC
ooling
onsult
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
How can R22 get into a R717 refrigeration system?
During service and maintenance:
• Using the same hoses, containers, tools and pressure vessels when working on
both R22 and R717 systems
•When second hand components from R22 systems are fitted on R717 systems
•Accidents, where the wrong refrigerant is charged to the system
Direct from the supplier of refrigerant:
•Supplier can use same charging system for R22 and R717
•Pressure vessels used for both R22 and R717
When changing refrigerant:
•Failing to get all oil and R22 out of a system which is changed to R717.
CC
ooling
onsult
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
How do R22 and R717 react in a R717 system?
Reactions will take place where R717 is in the liquid phase:
R22
+
R717
=> AMMONIUM
CYANIDE
CHClF2 + 5NH3 => NH4CN
+
AMMONIUM
CHLORIDE
+ NH4Cl
Will react with iron
Colorless
crystals
+
+
Dissolves in NH3 liquid
Very corrosive
AMMONIUM
FLOURIDE
2NH4F
Colorless crystals
Precipitates
NB: Reaction products are aggressive or very poisonous
CC
ooling
onsult
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Ammoniacyanide will react with iron in the system
R22
+
HYDROGEN
R717 + IRON =>
AMMONIUM
FERROCYANIDE
+ AMMONIUM +
CHLORIDE
AMMONIUM +
FLOURIDE
6CHClF2+28NH3+Fe =>(NH4)4Fe(CN)6 + 6NH4Cl + 12NH4F
+ H2
Dissolves in
Dissolves
Colorless
Non-
NH3 liquid.
in NH3 liquid
Crystals
conden-
Yellow color.
Corrosive
Precipitates
sible gas
Color change slowly
to grey/blue when exposed to air.
NB: Reaction products are aggressive or very poisonous
CC
ooling
onsult
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Ammoniumferrocyanide can react further:
R22
+
R717 +
IRON => IRONBLUE
+ AMMONIUM + AMMONIUM + HYDROGEN
CHLORIDE
FLOURIDE
18CHCLF2+72NH3+7Fe => Fe4(Fe(CN)6)3+ 18NH4Cl + 36NH4F + 9H2
Crystals
Dissolves
Colorless
Non
Strong blue
in NH3 liquid
crystals
condens-
Precipitates
Corrosive
Precipitates
ible gas
NB: Reaction products are aggressive or very poisonous
CC
ooling
onsult
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
How much is created?
Every kg R22 in a R717 system will create :
1 kg R22 =>
0,62 kg AMMONIUMCHLORIDE
NH4Cl
0,86 kg AMMONIUMFLOURIDE
NH4F
0,55 kg AMMONIUMFERROCYANIDE (NH4)4Fe(CN)6
IRONBLUE Fe4Fe(CN)6
0,004-0,012 kg HYDROGEN
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H2
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Where do the reaction products settle?
AMMONIUMCHLORIDE
NH4Cl
AMMONIUMFERROCYANIDE
(NH4)4Fe(CN)6
Settles as porous crystals where NH3
liquid evaporates, mainly in expansion
devices and evaporators
AMMONIUMFLOURIDE
NH4F
IRONBLUE
Fe4(Fe(CH6))3
Settles as crystals in the NH3 liquid where
they are created, mainly in high pressure
receiver and high pressure liquid line.
HYDROGEN
Assembles as non condensible gas in
condenser and / or receiver
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onsult
H2
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Secondary Effects
In the presense of zinc, Zincammoniumchloride Zn(NH3)2Cl
will be created:
Zincammoniumchloride
Zn(NH3)2Cl
Have a flux effect => reactive surfaces on metals
Ammoniumchloride
Creates a very corrosive environment
NH4Cl
Valves, regulators etc. can get “stuck” du to excessive corrosion.
CC
ooling
onsult
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Excessive Corrosion
CC
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onsult
Pistons from PM valves exposed in two weeks to
the corrosive environment of a R22 poluted R717
system.
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Practical examples of damage on systems
Blue
Blocked by corrosion
coloring
Check valves blocked
Sludge
Compressor bearing
break down
Pump damage
Blue coloring
Sludge
Blue coloring
Housing
filled with
sludge
Blue coloring
and
corrosion
Big
amount
of sludge
Pipe blocked
Pipes and
valves
totally
blocked
CC
ooling
onsult
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
How to clean the system?
AMMONIUMCHLORIDE NH4Cl:
AMMONIUMFLOURIDE NH4F
AMMONIUMFEEROCYANIDE
(NH4)4Fe(CN)6
IRONBLUE
Fe((Fe(CH6))3:
Corrosion products:
Dissolves in water
Dissolves in cold water and
decompose in hot water
Will not dissolve in water,
mechanical cleaning necessary
Mechanical cleaning
NB: Reaction products are aggressive or very poisonous
CC
ooling
onsult
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
Conclusions:
• R22 pollution of R717 systems can happen
• The quantity of reaction products is high
• Very corrosive environments can be created in the plant
• Valves, filters, controls and pipes can get blocked
• Compressors and NH3 pumps can be damaged
• Valves and controls can get stuck in corrosion
• System cleaning difficult and expensive
CC
ooling
onsult
M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, [email protected], ww.coolingconsult.com
Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415