REPLACEMENT OF HCFC-22 REFRIGERANTS WITH AMMONIA: A CHALLENGE FOR HOCKEY ARENAS IN QUEBEC Jean-Paul Lacoursière, P.E. University of Sherbrooke jpla@sympatico.ca Claude Dumas, P.E. Ville de Montréal cdumas@ville.montreal.qc.ca Tampa, FL, April 2009 1
Presentation Content Introduction Montreal Protocol on Ozone Depleting Substances Refrigeration System in Hockey Arena Replacement of HCFC-22 refrigerant Conventional Design Intrinsically Safer design Conclusion Tampa, FL, April 2009 2
Introduction Montreal Protocol on Ozone Depleting Substances Adopted in 1987 Canadian Legislations to phase out Ozone Depleting Substances starting 2010, forbidden construction or import of products or equipments using these substances Tampa, FL, April 2009 3
Introduction Refrigeration systems in hockey arena 500 hockey arenas (operated by municipalities) 400 arenas use HCFC22 as Refrigerant 35 operated by Montreal Very close to populated areas (meters) Tampa, FL, April 2009 4
Introduction Refrigeration systems in hockey arena In the 70 s HCFC22 was judged to be safer All these facilities have to be upgraded with an ozone friendlier refrigerant Ammonia is the refrigerant of choice Tampa, FL, April 2009 5
Conventional Design Ammonia Inventory 2258 kg Air Evaporative condenser Air 25 HP H 2 O PRV Liquid Oil separator Oil separator Oil separator D D D PRV Brine Surge Drum Evaporator Vaporiser Shell and tube Flooded Oil tank CMP 125 HP CMP 125 HP CMP 125 HP Safety valve to stack 5 000 lbs 2 268 kg High pressure receiver Tampa, FL, April 2009 6 H 2 O
Class T Machinery Room Tampa, FL, April 2009 7
External Ice Rink Tampa, FL, April 2009 8
HP Receiver sight glass leak ERPG3 750 ppm 45 m ERPG2 150 ppm 135 m Tampa, FL, April 2009 9
Ammonia Impact on Condominiums Tampa, FL, April 2009 10
Intrinsically Safer Design Atmosphere Ammonia Inventory 333 kg Evaporative Condenser PRV Drainer Air 25 HP N H 2 O Roof Class T Machine Room Liquid Oil Pot (E) (L) Surge Drum Evaporator P/H/X Flooded To Transfert System (F) To oil recirculating pump Brine (G) Compressor 125 HP (A) Oil Separator Compressor 125 HP Oil Separator Compressor 125 HP Oil Separator D D D (H) (B) (J) (C) Relief valve, outlet to water tank for capture (D) 735 lb 333 kg Service Tank To transfert pump Tampa, FL, April 2009 11 H 2 O 5 HP
Intrinsically Safer Design Critically Charged System Entire charge is located in the evaporator (s) A plates and frames heat exchanger and surge drum are used instead of a shell and tubes to minimize ammonia inventory Existing High Pressure receiver is modified for use as a Service Tank Tampa, FL, April 2009 12
Intrinsically Safer Design Two modes of operation are planned: Refrigeration mode all liquid ammonia is in the plates and frames heat exchanger evaporator and surge drum (winter) Standby mode All liquid ammonia is in the service tank (summer) Tampa, FL, April 2009 13
Intrinsically Safer Design This design allows a reduction of ammonia inventory to 333 kg. This represents a safer alternative than the base case with 2,268 kg Tampa, FL, April 2009 14
Intrinsically Safer Design Additional Mitigation Measures Ammonia scrubber on the emergency ventilation system with a vertical stack Closed circuit oil drainage Water tank to scrub ammonia relief valve discharges Ammonia detectors in evaporative condenser shelter and evaporative condenser with interlocks to equipment shutdown system Tampa, FL, April 2009 15
Intrinsically Safer Design Population exposure Ammonia exposure reduced below 25 ppm Tampa, FL, April 2009 16
Conclusion Ammonia inventory reduced from 2,268 kg to 333 kg with Critically Charged System (85%) Additional simple measures reduce impact of accidental release Water tank for relief valve discharges Ammonia refrigeration can be used with minimal risk and nuisance to nearby residents. Tampa, FL, April 2009 17