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www.coolingconsult.dkpdfR22_20POLUTION_20OF_20R7

VIEWS: 22 PAGES: 12

									         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?




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             M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, 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.



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  onsult
                M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, 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                  +      AMMONIUM                     +             AMMONIUM
                           CYANIDE                          CHLORIDE                                    FLOURIDE

CHClF2 + 5NH3 => NH4CN                                   + NH4Cl                           +             2NH4F
                              Will react with iron           Dissolves in NH3 liquid                     Colorless crystals
                              Colorless                      Very corrosive
                              crystals                                                                    Precipitates




                               NB: Reaction products are aggressive or very poisonous


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                      M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com
                                                                Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
               Ammoniacyanide will react with iron in the system

R22      +       R717 + IRON =>             AMMONIUM                 + AMMONIUM +                 AMMONIUM +
HYDROGEN
                                           FERROCYANIDE                 CHLORIDE                  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 ex-
                                    posed to air.
                              NB: Reaction products are aggressive or very poisonous

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      ooling
      onsult
                      M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, 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


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                            M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com
                                                                      Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
                             How much is created?

Every kg R22 in a R717 system will create :

                  0,62 kg AMMONIUMCHLORIDE                                               NH4Cl
                  0,86 kg AMMONIUMFLOURIDE                                              NH4F
1 kg R22 =>       0,55 kg AMMONIUMFERROCYANIDE (NH4)4Fe(CN)6
                          IRONBLUE Fe4Fe(CN)6
                  0,004-0,012 kg HYDROGEN                                 H2




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     onsult
              M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com
                                                        Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
              Where do the reaction products settle?
AMMONIUMCHLORIDE                                        Settles as porous crystals where NH3
NH4Cl                                                   liquid evaporates, mainly in expansion
AMMONIUMFERROCYANIDE                                    devices and evaporators
(NH4)4Fe(CN)6

AMMONIUMFLOURIDE                                        Settles as crystals in the NH3 liquid where
NH4F                                                    they are created, mainly in high pressure
IRONBLUE                                                receiver and high pressure liquid line.
Fe4(Fe(CH6))3

HYDROGEN     H2                                         Assembles as non condensible gas in
                                                        condenser and / or receiver


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                  M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, 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.




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                   M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com
                                                             Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
                      Excessive Corrosion




         Pistons from PM valves exposed in two weeks to
         the corrosive environment of a R22 poluted R717
         system.
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           M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com
                                                     Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
                     Practical examples of damage on systems
                         Blocked by corrosion                                                                                     Blue
                                                                                                                                  coloring
                                                                                   Check valves blocked

                                                                                                                                     Sludge
                                                                                Compressor bearing
                                                                                break down


                     Pump damage                                                                    Blue coloring
                                               Sludge
                          Blue coloring                                     Housing
Blue coloring                                                               filled with
and                                                                         sludge
                                                                                                                                 Big
                                                                                                                                 amount
corrosion
                                                 Pipe blocked                                                                    of sludge


                                                                                                                 Pipes and
                                                                                                                 valves
                                                                                                                 totally
                                                                                                                 blocked

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            onsult
                             M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com
                                                                       Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415
                            How to clean the system?
AMMONIUMCHLORIDE NH4Cl:                                               Dissolves in water


AMMONIUMFLOURIDE NH4F                                    Dissolves in cold water and
AMMONIUMFEEROCYANIDE                                            decompose in hot water
 (NH4)4Fe(CN)6


IRONBLUE      Fe((Fe(CH6))3:                                          Will not dissolve in water,
                                                                      mechanical cleaning necessary


Corrosion products:                                                   Mechanical cleaning

                          NB: Reaction products are aggressive or very poisonous

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     onsult
                 M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, 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



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ooling
onsult
             M. Sc. Mech. Per Skærbæk Nielsen, +45 28720673, +45 721990, skaer@mail.dk, ww.coolingconsult.com
                                                       Bjødstrupvej 77, 8310 Tranbjerg, Denmark, CVR: 28445415

								
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