CO2-avskiljning med syrgasförbränning -

nya tekniska möjligheter

Klas Andersson Avd. Energiteknik

Chalmers Tekniska Högskola

Chalmers Energikonferens 14 december 2012

• Combustion and CO2 capture

technologies – 12 researchers, 2 research engineers

– Power & industrial processes

• Combustion chemistry

• Heat transfer

• Flue gas cleaning: primary and secondary control

• Our objectives

– Knowledge development in thermal processes to reduce harmful emissions

– Develop the knowledge in close collaboration with power and industrial sectors

Air-Fuel Combustion

Air

Fuel Flue gas CO2: 10-20 % N2: 60-70%

Combustion Process

Oxy-Fuel vs. Air-Fuel Combustion - principle changes

Principle changes:

• Feed gas composition • Concentration of N2

• Recycle of flue gas • Concentration of combustion products • Residence time • Temperature

O2

Fuel

Flue Gas Recycling

Combustion Process

CO2:80-90%

Oxy-Fuel Combustion On-going and planned demonstration projects

• Yuong Dong PP (Korea)

• Ciuden Pilot plant (Spain)

• Futuregen 2 (US)

• Draxs PP (UK)

• Callide PP (Australia)

• Lacque plant (France)

Coal-fired power plant Utility: Vattenfall AB 411 MWe ηel=0.47 w/o capture ηel=0.39 w capture 2.5 million tonnes CO2/year

Nordjyllandsvaerket, Danmark

Rening av Kväveoxider (NOx) i syrgasförbränning

• Feed gas composition

• Concentration of N2

• Recycle of flue gas

• Concentration of combustion products

• Residence time

• Temperature

High-temperature NOx reduction

N2 + O2

2 NO Thermal

High-Temperature NOx Reduction

• Plug-flow • Gas-phase • NOin = 1000ppm • N2in = 0% • O2/CO2 • t = 1 s • λ = 0.9 • No Fuel-N

Figure: Normann. F, Andersson, K, Leckner, B, Johnsson, F, Fuel 87 (2008) 3579–3585, 2008

Reverse Zeldovich Reburning

Oxy-BECCS: Negativa

CO2 utsläpp?

Biomass in todays’ power plants Biomass contains Cl and alkali compounds:

• Introduces problems with corrosion above 500ºC

• Low efficiencey of plants burning biomass

• Efficiency improves with co-firing

• But corrosion problems remain

• Coal-related CO2 emissions remain

Combustion of biomass and coal in oxy-fuel combustion

• Is it possible to control or mitigate high-temperature corrosion

using the sulphation route for alkaline components?

• This would enable negative CO2 emissions and high electrical

efficiency

SO3 formation: Air-Fuel vs. Oxy-Fuel

• Feed gas composition:

oxygen availability

• Recycle of flue gas

• Concentration of combustion products: SO2 SO3

• Residence time

• Temperature

Biomass in oxy-fuel combustion – sulfation of alkali

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

50

100

150

200

250

Con

cent

ratio

n [p

pm]

Time [s]

K-Species

KCl AirKCl Oxy1KCl Oxy2K2SO4(s) Air

K2SO4(s) Oxy1

K2SO4(s) Oxy1

K2Cl2 Air

K2Cl2 Oxy1

K2Cl2 Oxy2

KOH AirKOH Oxy1KOH Oxy2

Biomass in oxy-fuel combustion

• Drax White Rose Power Station (UK)

• 2012: 400 MWe based on biomass

• 2020: Only biomass • 2017-2018: 304 MWe new Oxy-BECCS plant

Tack för att ni lyssnade!