Ph.d Student: Jacob Brix Supervisors: Peter A. Jensen, Anker D. Jensen

1. Coal devolatilization and char conversion under suspension fired conditions inO2/N2 and O2/CO2 atmospheres Ph.d Student: Jacob Brix Supervisors: Peter A. Jensen, Anker D. Jensen

2. The Oxy-Fuel Concept and Project Goal ”There is an urgent need for the full-scale demonstration of coal plants with CCS [2]” • Project Goal: • To provide experimental data and models for fuel conversion and NO emission at high concentrations of CO2 to promote the industrialization of oxy-fuel combustion. [1] IEA, Key World Energy Statistics, 2008 [2] IEA, Energy Technology Perspectives, 2008

3. Coal Devolatilization in O2/N2 and O2/CO2 Fuel: Bituminous coal, 90 – 106 μm. Equipment: Isothermal Entrained Flow Reactor. O2 Conc.: 5 – 6 vol. % (Inlet conditions), λ = 3. No difference is found in volatile weight loss when N2 is replaced with CO2. Fuel: Char sampled during devolatilization. Equipment: ThermoGravimetric Analyzer. O2 Conc.: 5 vol. %. Heating Rate: 5 K min-1. No difference is found in char reactivity when N2 is replaced with CO2 during devolatilization. CHEC Annual Day 2010, October 5

4. Char Conversion in O2/N2 and O2/CO2 Fuel: Bituminous coal, 90 – 106 μm. Equipment: Isothermal Entrained Flow Reactor. Reactor Temperature: 1373 K. λ: 3.3 – 9.8. No apparent difference is found in char conversion rate when N2 is replaced with CO2. Fuel: Bituminous coal, 90 – 106 μm. Equipment: Isothermal Entrained Flow Reactor. Reactor Temperature: 1673 K. λ: 1.9. A slower char conversion in CO2 than in N2 at high temperature witness of an effect of external mass transfer control. CHEC Annual Day 2010, October 5

5. Modelling Char Conversion Fuel: Bituminous coal, 90 – 106 μm. Equipment: Isothermal Entrained Flow Reactor. Reactor Temperature: 1373 K. λ: 3.3 – 9.8. The model captures experimental trends and predicts char conversion rates well over a wide range of experimental conditions. Number of Data Points: 108 O2 Conc.: 5 – 28 vol. % (Inlet conditions), λ = 1.9 – 15.2 Reactor Temperature: 1173 K - 1673 K. Model accuracy is generally similar or better than comparative literature model but requires less input parameters. CHEC Annual Day 2010, October 5

6. Project Status & Conclusions • Status: • Generation of an extensive data set covering suspension fired coal combustion in O2/N2 and O2/CO2. • Development of a predictive char conversion model with reliable kinetics covering zone I - III. • Parallel Work: • Generation of a large data set covering NO emission and particle temperature measurements in O2/N2 and O2/CO2 combustion in a laboratory fixed bed reactor. • Conclusions: • No differences has been found in volatile weight loss between N2 and CO2 based environments. • No differences has been found in intrinsic reactivity of char formed in O2/N2 and O2/CO2. • It is found that the lower diffusion coefficient of O2 in CO2 compared to N2 significantly influence char conversion in and near zone III. CHEC Annual Day 2010, October 5

7. Thank You For Your Attention! jac@kt.dtu.dk