Spray Cooling for Performance Enhancement of Air-Cooled Condensers J.S. Maulbetsch M. N. DiFilippo K. D. Zammit EPRI Advanced Cooling Workshop Charlotte, North Carolina August 9, 2008
Alternative Solutions Hybrid wet-dry systems – Commonly used for plume abatement – Several design options Spray-enhanced dry cooling – Technology adaptation from gas turbine units
Spray-Enhanced Dry Cooling In gas turbines, inlet air cooling racks used to enhance efficiency – Pre-cooling spray nozzles introduce fine mist In dry cooling systems, approach could be applied to pre-cool inlet air – Reduce capacity loss – Water use intermittent; rate ~25% full wet cooling
Spray-Enhanced Dry Cooling Without pre-cooling, ambient T increase from ~55º to 90ºF reduces capacity – For 235-MW unit, lose 10 to 12 MW (~5%) If air pre-cooled to 70% relative humidity, capacity loss reduced – For 235-MW unit, lose only 3 to 5 MW
Chinese Camp
ACC at Chinese Camp
Sprays in operation
Mist entering fan
Enhancement Spray
Spray Enhancement Test Setup
Hot Day Performance Average DB Temperature Profiles Crockett Single-Cell Spray Testing 100 95 DB Temperature, F 90 85 Deck DB Fan Outlet DB 80 B Exch DB 75 Glycol 70 Deck WB Fan Oultlet WB 65 60 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM
Maximum Cooling Effect Maximum Cooling Effect for Cell B Airflow 10 gpm 15 gpm 20 gom 25 gpm 5 gpm 18 16 Cooling Effect, deg F 14 12 10 8 6 4 2 0 0 5 10 15 20 25 Wet Bulb Depression, deg F
Cooling Effect Results Cooling Effect vs. Wet Bulb Depression Spray rate = 19 gpm 14 12 Cooling Effect, deg F 10 8 6 4 2 0 13.5 14 14.5 15 15.5 16 16.5 Wet Bulb Depression, deg F
Data Correlation T De ck DB -T Fan DB v s (T De ck DB -T De ck W B ) x S p ra y R a te S ingle-C ell T es ting, C roc k ett 14 12 10 T DeckDB -T FanDB , F 8 6 4 2 0 0 50 100 150 200 250 300 350 400 450 500 (T D eck D B -T D ec kW B )x S p ra y R a te , F x g p m
Correlation vs. Spray Rate (T De ck DB -T Fan DB) /(T De ck DB -T De ck W B ) v s S p ra y R a te S ingle-C ell T es ting, C roc k ett 0.8 (T DeckDB -T FanDB )/(T DeckDB -T DeckWB ) 0.6 0.4 0.2 0.0 0.0 5.0 10.0 15.0 20.0 25.0 S p ra y R a te , g p m
El Dorado Energy Center
El Dorado ACC
Effect on Backpressure Turbine Back Pressure vs Spray Rate - July ElDorado LLC Amb DB = 115 F 7 Steam Flow = 1,067,000 #/hr 110 F 6 Back Pressure, "Hg 105 F 100 F 5 95 F 90 F 4 3 2 0 20 40 60 80 100 120 Spray Rate, gpm/cell
Power Recovery Recovered Power vs Start Temp vs Spray Period 4,000 Water Budget = 35,210,000 gallons 3,800 Spray Period - 10am-8:59pm 3,600 Recov Power, MWHr 3,400 Water Budget = 26,410,000 gallons 3,200 10am-8:59pm 3,000 10am to 7:59pm 2,800 10am-6:59pm 2,600 11am-6:59pm 2,400 85 90 95 100 105 Start Temperature for Spraying, F
Now What? Showstoppers - Surface wetting - Rainback - Cost (Approx $0.5 M for 40 cell, plus $0.7 M to 2.0M for water treatment and storage) Approaches - Nozzle choice/location - Flow modeling - Demisters
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