spray cooling for performance enhancement of air...
TRANSCRIPT
Spray Cooling for Performance Enhancement of
Air-Cooled CondensersJ.S. MaulbetschM. N. DiFilippoK. D. Zammit
EPRI Advanced Cooling WorkshopCharlotte, 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
Spray Enhancement
Spray Enhancement Test Setup
Hot Day Performance
Average DB Temperature ProfilesCrockett Single-Cell Spray Testing
60
65
70
75
80
85
90
95
100
12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM
DB T
empe
ratu
re, F
Deck DB
Fan Outlet DB
B Exch DB
Glycol
Deck WB
Fan Oultlet WB
Maximum Cooling Effect
Maximum Cooling Effect for Cell B Airflow
02
468
101214
1618
0 5 10 15 20 25
Wet Bulb Depression, deg F
Coo
ling
Effe
ct, d
eg F
10 gpm 15 gpm 20 gom 25 gpm 5 gpm
Cooling Effect Results
Cooling Effect vs. Wet Bulb Depression
0
2
4
6
8
10
12
14
13.5 14 14.5 15 15.5 16 16.5
Wet Bulb Depression, deg F
Coo
ling
Effe
ct, d
eg F
Spray rate = 19 gpm
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 teS ing le -C e ll T es t ing , C roc k e t t
0
2
4
6
8
10
12
14
0 50 100 150 200 250 300 350 400 450 500
(T D e c k D B -T D e c k W B )x S p ra y R a te , F x g p m
T Dec
kDB
-TFa
nDB
, F
Data Correlation
(T De ck DB-T Fan DB)/(T De ck DB-T De ck W B) v s S p ra y R a teS ing le -C e ll T es t ing , C roc k e t t
0 .0
0 .2
0 .4
0 .6
0 .8
0 .0 5 .0 10 .0 15 .0 20 .0 25 .0
S p ra y R a te , g p m
(TD
eckD
B-T
FanD
B)/(
T Dec
kDB
-TD
eckW
B)
Correlation vs. Spray Rate
El Dorado Energy Center
El Dorado ACC
Effect on Backpressure
Turbine Back Pressure vs Spray Rate - JulyElDorado LLC
2
3
4
5
6
7
0 20 40 60 80 100 120
Spray Rate, gpm/cell
Back
Pre
ssur
e, "
Hg
Amb DB = 115 F
110 F
105 F
100 F
95 F
90 F
Steam Flow = 1,067,000 #/hr
Power Recovery
Recovered Power vs Start Temp vs Spray Period
2,400
2,600
2,800
3,000
3,200
3,400
3,600
3,800
4,000
85 90 95 100 105
Start Temperature for Spraying, F
Rec
ov P
ower
, MW
Hr
10am to 7:59pm
10am-8:59pm
10am-6:59pm
11am-6:59pm
Water Budget = 35,210,000 gallons
Spray Period - 10am-8:59pm
Water Budget = 26,410,000 gallons
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