Supercritical Boiler Technology

7/30/2019 Supercritical Boiler Technology

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LEADING THE INDUSTRYIN SUPERCRITICAL

BOILER TECHNOLOGY


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Alstom is a global leader in the world of power generation, setting the

benchmark for clean, innovative technologies to create customer value.

We supply major equipment in 25% of the installed base worldwide.

And weve developed an unmatched level of expertise in steam

generation and fuel combustion technology, having supplied more

than 400 GWe of boilers around the world.

Our boilers convert fuel into steam for the generation of electricity

cleanly, cost-effectively, reliably. As the No 1 supplier of boilers

worldwide, we can meet your project requirements today and in the

future with the design, manufacture and supply of state-of-the-art

systems and equipment.

HIGH-EFFICIENCY

SUPERCRITICAL TECHNOLOGY

Alstom pioneered supercritical steam generation and today leads

the industry in supercritical boiler technology. We have directly

supplied more than 80,000 MWe of supercritical boilers world-

wide. In addition weve trained and licensed other companies to

install an additional 72,000 MWe of Alstom supercritical boilertechnology. Globally, we have unmatched experience in tailoring

boiler designs to fuel properties.


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FOR CLEAN POWER TODAY!

Leading Through Technology

Today, our advanced high-efficiency pulverized coal supercritical

boilers offer plant owners many benefits. The technologys higher

steam temperature and pressure parameters deliver the most

economical way to improve plant efficiency and operatingflexibility, achieve fuel cost savings, and reduce emissions for each

kWh of electricity generated. Alstoms Advanced Supercritical

technology reduces allemissions, including CO2.

In fact, an efficiency improvement of 1 percentage point equals

2%-3% less CO2 emitted.

Alstom is also driving the development and deployment of the

next generation ofclean coal combustion technologies. We are

investing in the future of clean power across 22 development

centers and 13 laboratories around the world with the express

goal of minimizing environmental impact. One Alstom combustion

technology currently in the pilot plant demonstration phase

enables the capture

of CO2 emissions

from fossil fuels,

including pulverized

coal boilers. Known

as oxy-fuel firing,

this technology is

being tested in a 30

MWth pilot at the

Schwarze Pumpe

Power Station in Germany. Oxy-fuel firing is especially promising

for CO2 -free supercritical generation in the near term.

In addition to our own R&D activities, we participate in a

number of public development projects and partnerships,

including those sponsored by the European Union and the US

Department of Energy, as well as nearly all joint boiler materialsdevelopment programs.

Why Alstom Advanced

Supercritical?

Superior environmental

performance

Highest unit efficiency

Operating flexibility

Design tailored to fuel choice

Fuel cost savings


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Once-through supercritical technology offers important benefits

to plant owners, including:

Increased efficiency

Lower emissions levels

Lower operating costs

Greater operating flexibility

These benefits are possible because of the higher steam pressures

and temperatures which are a hallmark of the technology.

Understanding Supercritical Technology

Water/steam circulation systems are divided into two main

classifications: once-through, in which the water and steam

generated in the furnace waterwalls passes through only once;

and drum-type boilers, in which water/steam separation occurs,and water is recycled back to the waterwalls.

Supercritical conditions occur when the boiler pressure increases

above the critical pressure of 3,208 psi / 221.2 bar. Above this

point, two phase mixtures of water and steam cease to exist, and

are replaced by a single supercritical fluid. This eliminates the need

for water/steam separation in drums during operation, and allows

a simpler separator to be employed during start-up conditions.

Increased Efficiency and Lower Emission Levels

Plants that employ todays generation of Alstom supercritical

boilers can operate at cycle efficiencies in excess of 42-45% HHV

(44-47% LHV). As efficiency is increased, less fuel is consumed per

kilowatt-hour (kWh) with a corresponding decrease in emissions

per kWh. Because these units do not have thick-walled steam

drums, their start-up times are quicker, further enhancing

efficiency and plant economics. We continue to develop increasingly

efficient supercritical cycles for improved efficiency. Alstoms current

technology development will lead to our prototype ultra-supercritical

plant, operating at 1290 F (700 C) / 5075 psi (350 bar).

Lower Operating Costs

Lower fuel consumption is a direct consequence of higher

efficiencies. Fuel costs are a power plants largest operating costitem. Because the capital cost of supercritical plants is close to

those of subcritical plants, overall life cycle costs are often reduced.

THE SUPERCRITICAL

DIFFERENCE

Heat Rate Improvement vs.

Steam Conditions (Single Reheat)

Faster Start-up Time with Once-Through Design


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Greater Operational Flexibility

Todays market realities demand that units are not only designed

for baseload operation, but are capable of cycling and/or two-shiftoperation. Units must be designed for rapid response times.

Alstom once-through supercritical boilers have the ability to

respond and adjust to changes in load demand while maintaining

tight control of steam temperatures.

Alstoms supercritical boilers operate in the sliding pressure

mode, where pressure is reduced with load. This allows the

maintenance of relatively constant first-stage turbine temperature,

reducing the thermal stress on components as the unit is cycled.

Less stress translates into less maintenance and higher availability.

Todays generation of supercritical boilers boast high availabilities,

comparable to those of subcritical units, as well as improved plant

efficiency at lower loads.

Unlike drum boilers, once-

through units do not have a

fixed evaporative point: the

final evaporation occurs in the

furnace wall systems with steam

that is leaving the furnace

walls being superheated to a

certain degree. Since the

evaporation point is not fixed,

heat duties can be shifted

between the furnace and the

superheaters, allowing for

adjustment to changing

slagging and fouling

conditions caused by

changing fuel properties.

Sliding Pressure Operation

for Once-Through Boilers

1. Constant pressure operation

2. Modified sliding pressure operation3. Pure sliding pressure operation

Efficiency Improvement with Increasing Steam Conditions

Today

psi/OF/OF(bar/OC/OC)

SUBCRITICAL

Material Improvement Milestones

1960 1980 2000 2010 2020

Efficiency

Increase

5075/1350/1400350/730/760

SUPERCRITICAL

Mature technology

CONTINUED ADVANCEMENTS

Steam Conditions

2400/1000/1000167/540/540

3500/1000/1050240/540/565

3900/1075/1110270/580/600

4050/1110/1150

280/600/620

5075/1290/1330350/700/720

R&D ongoing USAUSC MaterialsConsortium & EC

AD 700 project(Ni-base)

R&D ongoing

Marketintro. by

JapanandEurope

DOE USC Matl.

DOE Steam Turbine Matl.AD 700 projectCOMTES 700


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Alstom technologies deliver realistic solutions for reliable clean

coal generation now. Our advanced supercritical boiler designs are

at the heart of todays state-of-the art plants, meeting the diverse

requirements of projects all over the globe and firing the full

range of international coals.

With Alstoms supercritical boiler design advantages, coal is

clean, economical and secure.

ADVANCED

BOILER DESIGNS

1 x 750 MWe, US


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Spiral Configuration

Benefits from averaging of lateral heat absorption variation

(each tube forms a part of each furnace wall)

Simplified inlet header arrangement

Large number of operating units

Use of smooth bore tubing throughout

entire furnace wall system

No individual tube orifices

Vertical Configuration

Simpler windbox openings

Simpler furnace water wall support system

Elimination of intermediate furnace wall transition header

Less costly to construct

Easier to identify and repair

tubes leaks

Lower water wall system pressure

drop thereby reducing required feed

pump power

Furnace Wall Designs

In todays market, two designs dominate for once-through units:

the spiral furnace tube arrangement and thevertical tube arrangement.

Design choice is governed by furnace size and customer preference

there are advantages to both, depending on project drivers.

The furnace walls are exposed to the greatest heat flux of all

heat-absorbing surfaces. This is because of the intense radiant

heat from the fireball.

For any given furnace size, the spiral wall unit in which the tube is

wrapped around the unit has fewer tubes than the vertical wall unit.

The vertical waterwall design uses internal ribbing in the tubes to

improve heat transfer. The vertical wall option is available for larger

units where lower perimeter-to-furnace plan area ratios result in

higher fluid flow per tube. The vertically oriented tubes are

self-supporting within the wall, allowing a simpler

support system. In fact, the relative simplicity of a

vertical wall furnace can result in significant

construction cost savings.


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Two-Pass, Pendant ArrangementTower Boiler Arrangement

Tower and Two-Pass Designs

Alstom provides tower and two-pass boiler designs, both of

which are widespread in power generation applications. In a tower

design, all heating surfaces are horizontal and drainable, and

generally in a single vertical configuration within the furnace

bounding walls.

Niederaussem Unit K, Germany

1 x 1000 MWe

Tower Design

Houshi Units 5-7, China

3 x 600 MWe

Two-Pass Design

Two-pass is a shorter design which incorporates vertical heating

surface in the radiant section of the furnace, and horizontal

surface in a parallel backpass. The selection of boiler configuration

is project specific, with consideration given to fuel ash

characteristics, site restrictions, and customer preference.

ADVANCED

BOILER DESIGNS

Nominal 900 MWe

2 x 800 MWe, South Korea


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Advanced Materials

High temperature materials enable the steam conditions and

corresponding thermal efficiency of advanced supercritical

steam cycles. Ideally, materials used in steam generator pressure

parts combine high temperature strength with reasonable

resistance to oxidation. In addition, the workability of the

materials and corrosion behavior are important attributes.

The increase of steam conditions primarily affects the waterwalls,

final superheater and reheater tubing, and the thick-walled

components, mainly the high pressure outlet headers and piping

to the turbine. Classes of materials include conventional and

advanced ferritic steel, austenitic steel, and nickel alloys.

Several boiler materials with improved mechanical properties

have been developed recently, and new materials still in the R&D

stages will enable higher ultra-supercritical steam cycles than are

today commercially available. Most materials development is

being conducted under national or internationally coordinated

programs. Alstom participates in nearly all cooperative materials

development programs, including the AD 700 / COMTES 700

program funded by the European Commission, and the US

Ultra-Supercritical Materials Consortiumsponsored by the

US Department of Energy.

Material Development Stages and Related Steam Parameter Limits

Membrane Wall

FutureOptions

Current

Past

Tubes SH Outlet Header

T92Nickel Alloy

Nickel Alloy Nickel Alloy

Austenitic NF 12,SAVE 12, VM12

7 CrMo VTiB 10 10HCM 2S

Austenitic E 911, P 92, P 122

Bar SHO0C - SH Temp0C - RH Temp

Austenitic P 9113 CrMo 4 4

260550570

270580600

290600620

300630650

350700720

260550570

270580600

290600620

300630650

350700720

260550570

270580600

290600620

300630650

350700720

9-12%Cr-Steels

X 20CrMoV 121

X 20CrMoV 121

Waterwall Tubes SH Outlet Header


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BEIJIANG CHINA

2 x 1000 MWe

Chinese Bituminous

Owner: Tianjian Guotou Jinning

Power Generation Ltd.

Commercial operation: 2010

Most advanced steam

conditions for China

COMANCHE 3 US

1 x 814 MWe

Powder River Basin coal

Owner: Xcel Energy


Will achieve one of the

lowest NOx levels in US

Recent ReferencesAlstom Advanced Supercritical Boiler Technology

A WORLD OF

SUCCESS STORIES

BELCHATOW POLAND

1 x 833 MWe

Lignite

Owner: BOT Elektrownia

Belchatow SACommercial operation: 2010

Highest efficiency level of

any brown coal-fired plant

in the country

IATAN 2 US

1 x 920 MWePowder River Basin coal

Owner: Kansas City Power

& Light


Features advanced vertical

wall construction

NEURATH F & G GERMANY

2 x 1100 MWe

Lignite

Owner: RWE Power AG


CO2, SO2, NOx and dust

emissions reduced by 31%

compared to existing

lignite-fired plants


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PEE DEE US

1 x 640 MWe

Eastern Bituminous

Owner: Santee Cooper


Designed to fire up to

30% petcoke

YONGHUNG SOUTH KOREA

2 x 800 MWe

International coal

Owner: KEPCO


First units based on the new

800 MWe Korean Standard

Thermal Power Plant

NING HAI CHINA

2 x 1000 MWe

Range of Chinese coals

Owner: Zhejiang Guohua Zheneng

Power Generation Co.


Another addition to Chinas

highest-efficiency fleet

WAI GAO QIAO PHASE II CHINA

2 x 900 MWe

Range of Chinese coals

Owner: Shanghai Municipal

Electric Company

Commercial operation:

2003-2004

Design replicated in Wai Gao

Qiao Phase III 2 x 1000 MWe,

scheduled to enter commercial

operation in 2008

1954: Earliest Extant Supercritical Generating Unit in the World

Alstom laid the foundation for todays Advanced Supercritical fleet at

Philadelphia Electric Companys Eddystone Unit 1 (US). Eddystone

pushed the technology for steam generating electric plants, pioneering

substantial increases in steam pressure, steam temperature and unit

size. At the time of start up, the 394 MWe Eddystone 1 was

the most efficient plant in the United States. It is still operating

at advanced steam conditions.

Initial steam cycle: 5293 psig, 1200/1050/1050 F

365 bar, 649/566/566 C

Current steam cycle: 5200 psig, 1130/1030/1030 F

359 bar, 610/554/554 C


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Alstom is a global leader in supplying firing systems for utility

boilers. Our firing systems burn a wide range of fuels, reduce

emissions levels and retain excellent levels of availability

and reliability.

Primary classes of utility-scale firing systems include suspension

firing and fluidized bed combustion.

In suspension firing, the fuel is either finely ground (for solid

fuels), atomized (for liquid fuels), or fired as a gas that quickly

burns as it mixes with combustion air and passes through the

furnace. Fuel is not recirculated in suspension firing as it is in

fluidized bed combustion.

FIRING SYSTEMS

Taean, one of the 20 x 500 MWe sliding pressure supercritical units using Alstom

technology in Korea. Since 1995, this unit has operated in daily two-shift operation

with high reliability.

State of the Art. Proven. Innovative.

2 x 800 MWe efficient and highly reliable supercritical steam generation since

1996 at the Schwarze Pumpe Station in Germany.


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TangentialFiring

Alstoms preeminent

suspension firing

system is tangential

(corner) firing,

with a track record of reliable performance, efficient combustion,

and very low nitrogen oxide emissions.

With tangential firing, a stable fireball is formed in the center of

the furnace over the entire operating range. Heat absorption

profiles are more predictable. As boiler load changes, corresponding

fuel elevations are deployed. Tangential firing has the additional

advantage of a stable flame pattern with any combination of

fuel elevations in service. Unbalances are minimized, and the

predictable lateral heat absorption profiles allow a more

conservative design of furnace wall circuits.

Alstoms family of TFS

2000 firing systems

employs both horizontal

and vertical staging of combustion air to produce ultra-low NOx

emissions. The latest addition to this product line is the TFS-XP

system, delivering enhanced performance to owners of new

pulverized coal units. Vortex control improvements to this design

result in better gas mixing, lower combustible gaseous emissions,

and uniform furnace outlet energy.

Circulating Fluidized Bed

Alstoms most popular fluidized bed combustion system is the

Circulating Fluid Bed (CFB). Used especially for more difficult to

burn fuels, CFBs also reduce NOx emissions because of their

lower combustion temperatures. Longer residence time of fuel in

the boiler is key unburned fuel is captured and recirculated for

further combustion. The addition of a sorbent (generally limestone)

also allows SO2 capture within the boiler for reduced SO2emissions without post-combustion capture.

Supercritical CFB For Maximum Fuel Flexibilityand Efficiency

Alstom has led the power industry in scaling-up utility-class CFB

boilers from 50 MWe to 600 MWe. Now customers can benefit

from our expertise in both supercritical and CFB technology

with Alstoms commercial designs for 400-600 MWe supercritical

CFB units. This premier technology application combines the

improved efficiency of advanced supercritical steam cycles with

the unparalleled fuel flexibility of CFBs. Based on rational design

innovations in larger size boilers, including 6 cyclones and higher

steam parameters, Alstoms supercritical CFB technology is

another step in bringing our customers added value, improving

the overall environmental performance of coal-fired plants, and

reducing global CO2 emissions.

Alstom An Industry Leader

Alstom introduced tangential firing

systems to the power generation

industry. Today, Alstoms family of

advanced low NOx tangential firing

systems leads the industry in

reduced emissions.

Supercritical CFB Boiler Design


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Alstom has the expertise and experience to make todays energy

production as clean and efficient as it can be. We are a world-

leading provider ofintegrated environmental solutions for power,

petrochemical and industrial plants including ways to improve

the performance and lifespan of your existing units.

In addition to high-efficiency boilers, Alstom's supercritical plant

offering includes supercritical turbines, mills, air heaters and post-

combustion equipment. Alstoms in-furnace and post-combustion

technologies can help meet todays strictest requirements for NOx,

SOx, VOCs, mercury, CO and particulates. And our integrated

boiler/backend designs will optimize your units sizing and

performance criteria, all with the lowest installed and operating costs.

Renewable targets? Alstoms experts in biomass co-firing can

reduce your carbon footprint and help your bottom-line.

Alstoms unparalleled breadth of product offering in Air Quality

Control (AQS) systems and Energy Recovery systems means we

can meet your toughest project requirements. With the largest

installed base in the world for air preheaters and coal pulverizers,

our customers benefit from superior performance, increased

efficiencies, and reliable service. And with more than 70 years

of experience in customizing AQS systems for new and existing

plants, you can depend on Alstom to deliver sustainable,

high-quality solutions at a competitive cost and performance ratio.

MORE SOLUTIONS

FOR CLEAN POWER

1 x 1000 MWe, Germany


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For further information,

please contact one of our

Regional Offices or e-mail

[email protected]

Western Europe/South America/

Africa/Middle East

Sales Region

Tel: +33 (0)1 46 29 16 32

Fax: +33 (0)1 46 29 16 70

Central and Eastern Europe/India

Sales Region

Tel: +49 711 917 1269

Fax: +49 711 917 1222

Tel: +91 124 4221 100

Fax: +91 124 4221 660

Asia Pacific

Sales Region

Tel: +33 (0)1 46 29 15 85

Fax: +33 (0)1 46 29 16 70

North America/Mexico/

Central America/CaribbeanSales Region

Tel: +1 860 285 2348

Fax: +1 860 285 4172

Ref: PWER/BPROB/BOILERTECHNO/eng/BUBB/12.07/US/3329 ALSTOM 2007. Alstom, the

Alstom logo and any alternative version thereofare trademarks and service marks of Alstom.The other names mentioned, registered or not,are the property of their respective companies.Please note: The information in this brochure isof a general nature, and may not be applicable foruse in any specific application. Reprinted 2007.

www.power.alstom.com

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