design advancements in usc pulverized coal boiler design improvements • conclusion remarks the...

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