IMPROVING COOLING SYSTEM EFFICIENCY WITH PRE-COOLING AJ Schutte 15 August 2012
Introduction National power network under strain Electricity price increases Mining is electricity intensive Cost effective mining Inefficient mine cooling and ventilation system
South African mining Reduce operational cost SA mining depth requires cooling Surface refrigeration system System components Dams and transfer pumps Heat exchange towers Refrigeration machines
Surface refrigeration system layout
Mine cooling Surface refrigeration Cooling load Mine production water Bulk air coolers (BAC) Cooling components Pre-cooling towers Refrigeration machines
Mine water quality Production cause water temperature increase Salts dissolve Evaporation increases solution concentration Water treatment Solid particles suspension Settlers Mine production surpass settlers and treatment
Pre-cool towers Layout Fan Mist eliminators Spray nozzles Fill Production water cools Crystals + solid particles
Case study: Replace pre-cool towers Mine production exceeding infrastructure Summer refrigeration operate at 100% Winter period maintenance High efficiency film fill used Tower fan maintenance
Replaced pre-cool towers Original design exceed requirement New fill specified Direct drive fans New fill vibrates
Results - Temperatures Inlet temperature of 30 o C Flow 340l/s Old tower outlet temperature 23 o C New tower outlet temperature 19 o C Improvement of 4 o C
Results - Electricity 1 MW saving through out the day
Conclusion Replacing mine pre-cool towers resulted in a 4 o C colder outlet temperature This resulted in 24hour average electricity saving of 1MW Fans utilisation increased Winter period pre-cooling now possible
The End Questions? Thank you