Post on 14-Oct-2020
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
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