POWER GENERATION FROM COAL USING

SUPERCRITICAL CO2

D R Q I A N Z H U

9 T H I N T E R N A T I O N A L F R E I B E R G C O N F E R E N C E O N I G C C & X T LT E C H N O L O G I E S

3 - 8 J U N E 2 0 1 8 , B E R L I N , G E R M A N Y

SCOPE OF PRESENTATION

Q I A N Z H U

Senior analyst and author at the IEA Clean Coal Centre

A brief introduction to power cycles using •supercritical CO2 (sCO2) as a working fluid

Applications and benefits •

Approaches to power generation using sCO• 2 cycles

Technical challenges•

Recent advances in developing sCO• 2 cycles for power generation

Concluding remarks•

Non• -explosive, non-flammable, non-toxic and readily available at low cost

Reaches a supercritical state at •moderate conditions — 7.4 MPa and 31°C

Large fluid density (and low •pressure ratio) keeps turbomachinery small

CO 2 AS A WORKING FLUID

(Turchi, 2013)

Nuclear

Geothermal and waste heat

APPLICATIONS

Fossil fuel

(All images from Wilkes, 2014)

Solar power Ship-board propulsion

MAIN BENEFITS

High thermal efficiency at moderate temperatures•

Smaller size of all system components and a nominal gas path diameter, •leading to smaller plant footprint

Simple cycle and reduced balance of plant requirements•

Possibly lower capital, operation and maintenance costs•

Oxy• -combustion sCO2 cycle facilitates carbon capture

Two primary approaches to electricity generation using sCO2 cycle have been investigated

• indirect-heating, closed-loop Brayton cycle

directly• -fired, semi-closed, oxy-fuel Brayton cycles

sCO 2 CYCLES FOR POWER GENERATION

An indirect-heating, recuperated, closed Brayton cycle (US DOE)

INDIRECT-HEATING, CLOSED sCO 2 BRAYTON CYCLE

A directly-fired, semi-closed oxy-combustion sCO2 cycle (US DOE)

DIRECT-FIRED, SEMI-CLOSED sCO 2 CYCLES

TECHNICAL CHALLENGES

Turbomachinery design and performance•

Recuperator• design, performance and cost

sCO• 2 combustor (direct-fired sCO2 cycle)

Materials•

Sub• -components: valves and seals

Cycle configuration, system integration•

10 MWe high-pressure, high-temperature turbine rotor design (Turchi, 2013)

RECENT DEVELOPMENTS— key components

Toshiba’s 5 MWt supercritical oxy-combustor (Fetvedt, 2016)

Recuperator design(Carlson and others, 2014)

Materials testingMaterials testing(Holcomb and others, 2016)

RECENT DEVELOPMENTS— NATURAL GAS FUELLED ALLAM CYCLE

50 MWt Demo plant in La Porte, TX, USANatural gas fuelled, oxy• -combustion with combustion product CO2 ready for storageMirrors design of commercial plant to ensure •

scalabilityIncludes all components of the Allam Cycle•

Plant will undergo full performance evaluation•

A gas-fuelled 300 MWe commercial plant under development

Pre• -FEED study completed on full-scale plant; FEED and early development work has begun

Toshiba undertakes commercial turbine design•

(Fetvedt, 2016)

(Fetvedt, 2016)

RECENT DEVELOPMENTS— COAL-BASED ALLAM CYCLE

Integrate core Allam Cycle with •

existing gasification systemsSimple power cycle•

Highly efficient and flexible, lower •

costsAdditional R&D needs to include •

syngas clean-up process, handling of corrosion from impurities, and syngas combustor for low-CV fuels

(Fetvedt, 2016)

RECENT DEVELOPMENTS— ECHOGEN HEAT ENGINE EPS100

First commercial • 8 MWeprototype heat engine

Use recuperated closed sCO• 2 Brayton cycle

Turns waste heat to electricity•

Lower costs•

Images from: www.echogen.com

CONCLUDING REMARKS

The sCO• 2 Brayton cycles hold great potential for providing alternative power generation systems that can achieve higher plant efficiency and full carbon capture at lower costs

Two pathways have been identified for power generation from fossil fuels using •sCO2 cycles:

– indirect-heating closed Brayton cycle (coal based PC boiler/furnace)– directly-fired semi-closed sCO2 cycle (coal derived syngas and natural gas)

Some outstanding technical issues need to be addressed•

Extensive R&D has been carried out and significant progress has been made •recently in developing sCO2 cycle power systems. If solutions can be found to meet all the technical challenges in developing the sCO2 power cycles, they can have a huge impact on future power generation from coal in a carbon constrained world

THANK YOU FOR LISTENING

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