Developments in circulating fluidised

bed combustion

by Dr Qian Zhu

qian.zhu@iea-coal.org.uk

IEA Clean Coal Centre Webinar

Wednesday 22 May 2013

Advantages of CFBC technology

The main advantages:

• Fuel flexibility

• Low emissions

• Stable operating conditions and good turndown

and load following capability

Current status of CFBC technology

• Efficiencies: subcritical CFB 38-40% (LHV), SC

CFB up to ~45% (LHV)

• Availability: average availability of 90% or

higher

• Operational flexibility

• Fuel flexibility

• Emissions: >95% desulphurisation rate, NOx

<200 mg/m3 , PM 20-50 mg/m

3

• Steam cycles

• Plant sizes: Lagisza 460 MWe, Baima 600 MWe,

Samcheok 550 MWe

• Applications: >46 GWe coal-fired power

generating units in operation worldwide

460 MWe Łagisza SC CFBC Unit

Design variations

FW’s single grid CFBC design Alstom’s pant-leg design

Furnace design

Solid separation systems

FW’s Compact Separator

Solid separation systems

B&W’s U-beam solid separator

Scale-up principle for cyclones

arrangement

External heat exchanger (EHE)

Integrated recycle heat

exchanger

CFBC Boilers - 26Nos (18 In

Operation)

Less than 30 Mwe - 5

30 to 70 Mwe - 6

>70 to 135 MWe - 11

250 MWe - 4

Increase in capacity of CFBC boilers

Increase in capacity of CFBC boilers

Recent CFB units installed, planned or under construction

Advanced steam cycle conditions

Advanced steam cycle with once-through boiler technology:

• 460 MWe Lagisza power plant: 27.5 MPa/560ºC/580ºC

• 600 MWe Baima demonstration unit: 24.5

MPa/571ºC(±5ºC)/569ºC(±5ºC)

• 330 MWe OGK-6, Novocherkassk plant: 24.7

MPa/565ºC/565ºC

• 550 MWe CFBC units at Samcheok Plant: 25.7

MPa/603ºC/603ºC

Other developments

• Fluidised bed ash coolers

• Improvements in refractory system designs,

fuel and sorbent feed system designs, and

ash extraction equipment design

• Modifications and optimisations in the design

and operating parameters of co-combustion

CFBC boilers

Various designs for fluidised-bed ash cooler

c) B&W’ fluidised-bed cooler

Developments in Oxy-CFB technology

A simplified flow diagram of an oxy-CFB combustion process

Design challenges

• Differences between air and

oxy-fuel combustion

conditions

• Boiler size

• Heat duty and heat transfer

• Pollutants emissions under

oxy-firing conditions

• Bed agglomeration

• Sulphur sorbent utilisation

efficiency

• Air ingress

• Material

R&D activities

R&D facilities

• CANMET Energy Technology Centre in Canada: 0.1 and

0.8 MWth CFB test rig

• Institute for Clean and Secure Energy, University of

Utah (USA): pilot-scale CFB test rig

• CIRCE at University of Zaragoza, Spain: 90 kWt oxy-

CFB reactor

• Advanced Energy Technologies, Czestochowa

University of Technology (Poland): 0.1 MWth CFB test

rig

• Technical Research Centre (VTT) of Finland: 30-100 kW

CFB combustor

• Universities in China

• Foster Wheeler and Alstom

CIUDEN Oxy-CFB demonstration project

The CIUDEN TDC for CO2

Capture

CIUDEN Oxy-CFB demonstration project

The main components of the CFB boiler at CIUDEN TDC

Performance and cost

Power consumption and output

Oxy-PC versus oxy-CFB

Advantages over oxy-PC include:

• reduction of unit size

• easier transition between air and O2 firing mode

• simple implementation

• ability to burn low-reactive fuel

• reduced air ingress

• lower excess O2

Conclusions

• CFBC technology has advanced significantly in

recent years making it competitive for coal-

fired power generation.

• Oxy-CFB technology is developing rapidly and

will evolve as the industry gains experience

and incorporates new innovations.

It is expected that CFBC technology will see

increasing applications in the power generation

industry in the near future.

Thank you very much for your time

Questions?

Qian Zhu, qian.zhu@iea-coal.org.uk

IEA Clean Coal Centre, http://www.iea-coal.org