REPLACEMENT OF HCFC-22 REFRIGERANTS WITH AMMONIA: A CHALLENGE FOR HOCKEY ARENAS IN QUEBEC

Transcription

1 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

2 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

3 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

4 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

5 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

6 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 lbs kg High pressure receiver Tampa, FL, April H 2 O

7 Class T Machinery Room Tampa, FL, April

8 External Ice Rink Tampa, FL, April

9 HP Receiver sight glass leak ERPG3 750 ppm 45 m ERPG2 150 ppm 135 m Tampa, FL, April

10 Ammonia Impact on Condominiums Tampa, FL, April

11 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 H 2 O 5 HP

12 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

13 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

14 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

15 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

16 Intrinsically Safer Design Population exposure Ammonia exposure reduced below 25 ppm Tampa, FL, April

17 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