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Design Advancements in USC Pulverized Coal Boilers
Dr Bin XuDoosan Babcock Energy America LLC
Presentation Summary
• The Drive for High Efficiency PC Power Plant
• European Status
• Evolution of POSIFLOWTM Furnace Design
• Boiler Design Improvements
• Conclusion Remarks
The Drive for High Cycle Coal Fired Power Plant
• Coal is the most abundant and cheapest fossil fuel source • Higher market stability than oil and natural gas, guarantees to stable COE• Significant growth in emerging markets (China, India) along with modest growth in mature market (USA, EU)• Addition of 3 billion tons of CO2 emissions annually • More stringent regulations on emissions and carbon footprints
.
1960 1980 2000 2020
35
40
45
50
30
FERRYBRIDGE
DRAXCASTLE PEAK
RATCLIFFE
MERI PORI
HEMWEGWANGQU
THERMIE 700 TARGET
DBE BAT
COST 522 TARGET
Cycle Efficiency (%HHV)
1990 2000 2010 2015
-30%
-20%
-10%
0%Traditional NaturalCirculation Boiler
Advanced Supercritical
Boilers
HEMWEG
COST 522
TARGETTHERMIE 700TARGET
% Reduction in CO2emissions
DBE BAT
2020
Efficiency Improvements for Emissions Reduction
Today’s best available USC boiler technologies offers ~18% reduction in all emissions per MW compared to traditional sub-critical boiler
Benefits of Higher Steam Conditions
SUBCRITICAL SUPERCRITICAL SUPERCRITICAL ULTRASUPERCRITICAL
Pressure psi 2400 3600 3800 4350
Main steam / reheat temp 1005F / 1005F 1060F / 1060F 1075F / 1075F 1110F / 1130 F
Typical Net Plant efficiency(gross) 38% 42% 43% 45%
CAPITAL COSTS
Boiler island Base 1% 1.50% 2%
AQCS Base -3% -4% -5%
CONSUMABLES
Coal Base -10% -13% -18%
Limestone Base -10% -13% -18%
Ammonia Base -10% -13% -18%
Cooling Water Base -10% -13% -18%
Auxiliary Power Base -10% -13% -18%
EMISSIONS
CO2 Base -10% -13% -18%
NOx Base -10% -13% -18%
SOx Base -10% -13% -18%
Mercury Base -10% -13% -18%
-10%
-10%
-13% -18%
-13% -18%
.
European Status
Typical European Unit
• High boiler efficiency boiler plant >91.0% (HHV) with steam conditions of around 4130 psi, 1115°F / 1150°F (current state of art)
• Carbon capture ready
• POSIFLOW™ furnace design
• Single stream air and gas system, no spare mills
• Single cooling tower incorporating stack
• Modularization to minimize construction schedule
POSIFLOWTM vertical tube low-mass-flux and spiral furnace arrangements
Evolution of Furnace Wall Technology
11NoCirculating pumps
20-25%30-35%30%Minimum load in once-through operation
Very GoodGoodBadLoad following
LowModerateHighTube-to-tube temperature differences at furnace wall
exit
LowHighHighFeed-pump power
NoNoYesAdjustable flow orifices
PositiveNegativeNegativeFlow characteristic
~205~450~370Mass flux at full load
(lb/ft2.s)
POSIFLOWTM
Low Mass Flux Design
Spiral FurnaceHigh Mass Flux
Design
Universal Pressure
High Mass Flux Design
Main differences between furnace arrangements for once-through boilers
Evolution of Furnace Wall Technology
Vertical Tube POSIFLOW™ Furnace
.
Significant advantages over spiral furnace boilers
(800 MWe unit)
Reduced Constructionschedule
Reduced Construction risk
Reduced Capital cost
�vertical panels and horizontal welds require less temporary support and are more accessible
�4,000 fewer welds�50,000 fewer construction hours�Lower steel weight by 850,000 lbs
.
(800 MWe unit)
Simpler maintenanceReduced Operational
cost
Advantages over spiral furnace boilers � Reduced pressure drop by ~ 140 psi� Lower feed pump power (~ 1 MWe)� Lower Benson load (25%) � Less susceptible to variations in heat input
Advantages over other vertical tube furnaces (high mass flux)� Sliding pressure for 2 shift operation� No orifices� Lower feed pump power
Through life benefits
Vertical Tube POSIFLOW™ Furnace
The Supercritical Downshot Boiler- for low volatile coals (anthracite)
• The advent of the low mass flux vertical tube furnace for wall fired furnaces can also be applied to the downshot furnace:
World’s first downshot POSIFLOWTM units (2 x 600MWe )Zhenxiong, China operation in 2010.
Design Improvements: Two-pass Boiler
SUSPENSION DECK
SE
PA
RA
TO
R V
ES
SE
LS
PLATENSUPERHEATER
SECONDARYREHEATER
FINALSUPERHEATER
PRIMARYSUPERHEATER
PRIMARYREHEATER
ECONOMISER
+16000
+24050
+32250
+39750
+50445
+60780
+75800 TOS
+65145
+18148
+23248
+28348
BURNER LEVEL
10500 8500 1500013000
17480
20700
0 1 2 3 4 5 6 7 8 9 10
SCALE
Recent design optimization exercise on boiler resulted in:
• 30% reduction in pressure part weight
• 16% reduction in steelwork weight
• 13% reduction in Boiler Island cost
Current Modified
• Flexibility in swan-neck pipes
• Flexibility in tubes and roof
Advantages
• Lowers top steel by 13 ft
• Reduced boilerhouse cost
• Reduction in shipping and transportation costs
• Reduced erection cost
• 50% reduction in slings
• 50% fewer welds
• Makes header unbalance work for you
• New DB method
Estimated Saving per unit: $1.75m
Eliminate Stub Pipes
Design Improvements –1
Current Design
• Advantages
•Fewer separators•Fewer risers•No arch downcomers•Reduced boiler width•Reduction in shipping•Reduced erection cost •Reduced weight•Doosan Babcock method
DisadvantageBoiler steam/water volume reduced – response to load change to be quantified – not thought significant
Improved Design
Estimated Saving per unit: $2.9m
Separators, Roof & Vestibule Circuitry
Design Improvements - 2
Design Improvements –3
Current• Integration of Hot and Cold Structures
- 70% reduction in hot structure weight, simpler to erect
• Modularization- reduce site construction costs and saves schedule
• Efficient Plate Gilled Economizer
- Clear gas lanes each bank
- Very resistant to erosion
- Lower pressure loss
- Fewer sootblowers
4.5 inches
5.0 inches
4.5 inches
5.0 inches
Over 25,000 MWe of power plant with H-fin
type of economizer have been installed.
Recent H-fin Econ order for a 750 MWe PRB
coal fired plant in US
• Reduce Airheater Leakage- Bisector Sec. AH + Tubular Pri. AH (2% leakage)
USC Reference Boiler for US ( PRB Coal)
Boiler Design Features:
• 800 MWe USC steam@ BSV : 5250 psi/1260 oF /1295 oF
• Sliding pressure, reheat control to 60% MCR, 25% MCR Benson load
• POSIFLOW™ furnace, two-pass, opposed wall firing
• Single stream (1x airheater, 1x FD Fan, 1x PA Fan, 1x SCR)
• 4 mills, 32 low NOx burners with OFA
• AH outlet gas temperature: 248 oF
• NOx emission: 0.03 lb/mm Btu
• Boiler Efficiency: 87.2% (HHV)
• Plant Efficiency: 42.7%(HHV)
SCALE OF METRES
0 5 10 15 20 25
22187.4 FURNACE WIDTH
+20830 BURNER
+17808HOPPER KNUCKLE
+0.0m (GRADE)
+7600
+25461 BURNER
+30093 BURNER
+34724 AFTER AIR
+38700
+48590
+54600
+70600 ROOF TUBES
+77550PENTHOUSE ROOF
MAIN STEAMOUTLET
REHEATEROUTLET
+75570
+76570+76170
+73100
+72450
SCRAPER CHAINCONVEYOR (SCC)
+17000 TOF
REHEATER
PRIMARYSUPERHEATER
+50520
ECONOMISER
ECONOMISER
+49520
+44620+44620
SEPERATORVESSEL
FINALSUPERHEATER
REHEATEROUTLET
PLATENSUPERHEATER
THERMOPROBE
TO STORAGEVESSEL
A A
B
B15747.4
+81000 TOS
4300
10000 11200 12800 11000
5322.3
6555 6555
S/B S/B
S/B S/B S/B
+47360 TOF
+69500 TOF
REHEATERINLET
BB
B
S/B S/B
S/B S/B
S/B S/B S/B
S/B S/BS/B S/B S/B
F/B F/B
Design based on Doosan Babcock’s best available Advanced Supercritical Boiler Technology for near term US market.
.
Conclusion Remarks
• Raising plant efficiency by employing advanced steam conditions is the primary solution to reduce the overall plant emissions including CO2 from coal fired power plants
• Today’s best available USC power plant technology offers good improvement in cycle efficiency with low risk, can achieve up to 18% reduction of overall all plant emissions compared to traditional sub-critical power plants
• The POSIFLOW™ furnace is now accepted worldwide as a simple, self compensating and cost effective design
• USC power plant’s CAPEX comparable to conventional plant for same MWe, with substantial reduction in OPEX due to less consumption in fuel and AQCS feed stocks
• Doosan Babcock is taking steps to reduce the total cost of ownership of boiler plant and will continue to do so on a continuous basis
“Doosan Babcock Energy remains committed to be an international leader in delivering advanced clean energy
technologies, products and services”
Thank you for your attention
http://www.doosanbabcock.com