A Fundamental Study of Biomass Oxy-fuel Combustion and Co-combustion

1. A Fundamental Study of Biomass Oxy-fuel Combustion and Co-combustion Timipere S. Farrow Prof. Colin Snape: Supervisor Review Objectives Experimental Results Conclusion Future work

2. Presentation overview • Introduction • Carbon capture technologies • Detailed oxy-fuel combustion process • Objectives • Lab Scale Experimental techniques • Thermo gravimetric Analysis (TGA)/Horizontal Tube Furnace (HTF) • Drop Tube Furnace (DTF) • Results • Combustion reactivity of Biomass Fuel under oxy-fuel and air combustion • Co-firing sawdust and coal to identify the effect of biomass on coal char burnout • Co-firing in (DTF), the effect at higher temperature combustion Introduction Overview Objectives Experimental Results Conclusion Future work

3. Introduction • The presence of CO2 and other green house gas emissions in the atmosphere has become more problematic because of their negative environmental impact on climate • Stringent environmental laws on CO₂ emissions from coal combustion. World energy consumption is predicted to rise to 44% and CO₂ emissions to 39% in 2030 [1] • Increased interest in power generation industry towards technologies, which help to reduce CO2 emissions from fossil fuels combustion by means of CO₂ capturing. 1. International energy outlook, 2009 Introduction Review Objectives Experimental Results Conclusion Future work

4. Leading Techniques for CO₂ Capture • Biomass co-firing Presents a potential technique Introduction Review Objectives Experimental Results Conclusion Future work

5. Why Biomass and co-firing?Potential option for renewable based power generation • Unlike fossil fuels, biomass fuel is renewable and CO2-neutral in the sense that the CO2 it only releases recently fixed carbon when combusted thereby closing the carbon loop on a short time • Partial substitution of coal for combustion • In the UK, legislation is strong on CO₂ reduction to meet Kyoto target and EU’s target to reduce CO₂ emissions by 20% by 2020. • Hence the combination of oxy-fuel combustion with biomass fuel become a CO2 sink for power plants Introduction Review Objectives Experimental Results Conclusion Future work

6. Oxy-fuel combustion Process for cleaner fossil fuel utilisation • Fundamental studies of oxy-fuel coal combustion have demonstrated that oxygen concentrations in the range 30-40% produced temperature profiles matching those of conventional air firing with lower NOx and SOx emissions. Introduction Review Objectives Experimental Results Conclusion Future work

7. Objectives • To investigate the behaviour of biomass under oxy-fuel conditions in comparison to air fired condition in terms of: • Volatile yield • The associated nitrogen partitioning between char and volatiles in order to monitor NOx emissions. • Kinetic parameters which are useful for design of biomass oxy-fuel combustion system. 2. To investigate how biomass will affect coal char burnout during co-firing under oxy-fuel and air firing with particular emphasis on the catalytic effect of biomass-contained alkali and alkaline metals on coal char burnout Introduction Overview Objectives Experimental Results Conclusion Future work

8. Sawdust Devolatilisation Devolatilisation Devolatilisation Drop tube Furnace Horizontal tube furnace Thermo gravimetric analyser Thermo gravimetric Horizontal Tube Analyser (TGA) Furnace (DTF) Furnace (HTF) Re-firing Combustion Char Char Combustion Schematic diagram of experimental Approach Introduction Review Objectives Experimental Results Conclusion Future work

9. Thermo gravimetric analyser (TGA)and horizontal tube furnace (HTF) heating rate of 150⁰C/min • TGA Heating rate is miles away from reality yet give fundamental combustion information TGA HTF, replicates TGA char production Introduction Review Objectives Experimental Results Conclusion Future work

10. Drop Tube Furnace, High heating rate, short resident times (200-600ms) and 1600⁰C • High heating rate and high combustion temperatures, close to reality Introduction Review Objectives Experimental Results Conclusion Future work

11. What Effect does CO₂ have on volatile yield? • There is no particle size effect at both conditions except for the smallest particle size at 1100⁰C • The impact of oxy-fuel firing is pronounced at 1100⁰C due to volatile –char gasification reaction but low at low temperatures due to Poor thermal conductivity Introduction Review Objectives Experimental Results Conclusion Future work

12. Why do we need to maximise Nitrogen (N₂) yield in the volatile phase? • Char N₂ contribute to NOx formation • Beneficial to oxy-fuel due to high transformation of N₂ into the gaseous state at high temperature Introduction Review Objectives Experimental Results Conclusion Future work

13. TGA Combustion reactivity of biomass chars at 375⁰C • CO2 does not have effect on the combustion reactivity of the chars at low temperature hence the burnout is identical with air fired condition • Insignificant particle size effect is seen in during burnout in both conditions except for the smallest particle size. Introduction Review Objectives Experimental Results Conclusion Future work

14. Impact of low char combustion temperature on kinetic parameters • Variation is less due to poor thermal conductivity effect of CO2 compared with that of N2 Introduction Review Objectives Experimental Results Conclusion Future work

15. Benefits of Co-firing (TGA Analysis) • Improved burnout of blend but slightly more pronounced under oxy- fuel condition • Strong synergetic effect: an indication of interactions Introduction Review Objectives Experimental Results Conclusion Future work

16. Moving close to Reality, does biomass char still affect coal char burnout? Introduction Review Objectives Experimental Results Conclusion Future work

17. Improved coal char combustion, effect of catalytic inorganic metals in biomass fuel Introduction Review Objectives Experimental Results Conclusion Future work

18. conclusions • High reactivity observed for CO₂ at high temperature due to gasification reaction. • No particle size effect, can use bigger particle size for pulverised biomass fuel combustion systems • Biomass improved coal combustion. There is chemical interaction between the two fuels during co-combustion • Inorganic minerals in biomass catalysed coal char combustion Introduction Review Objectives Experimental Results Conclusion Future work

19. Completing PhD, what is left to be done • Devolatilisation of sawdust in DTF at different temperatures and different residence times • DTF char burnout • Co-firing at different temperatures and residence times at the two atmospheres • DTF burnout of blend chars • TGA burnout analysis of DTF chars (sawdust and blend chars) in air and oxy-fuel conditions Introduction Review Objectives Experimental Results Conclusion Future work

20. Thanks for YOUR Attention Introduction Review Objectives Experimental Results Conclusion Future work