Kinetic model of condensable co-products release during biomass torrefaction

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(1)Kinetic model of condensable co-products release during biomass torrefaction T. Nocquet, C. Dupont, J.M. Commandre, M. Grateau, S. Thiery, M.H.NGuyen, S. Salvador CIBSCOL – 04/06/12. 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. What is biomass torrefaction? Smooth thermal decomposition in default of air Between drying and pyrolysis – T = 200-300°C – Solid residence time = 10 min to several hours – Atmospheric pressure Volatile matter: • Gas (CO, CO2) • Condensable species (H2O, acids…). Biomass C6H9O4 + moisture~20% >70w%. Properties get more coal-like. Torrefied biomass C6H8O3 +moisture~3%. – – – –. H/C and O/C decrease Hydrophobic nature Energy densification Better grindability and flowability. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 2.

(2) 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. What is biomass torrefaction? Biorefinery approach Burnt or removed as waste Source of Green chemicals Volatile matter: • Gas (CO, CO2) • Condensable species (H2O, acids…). Biomass C6H9O4 + moisture~20% >70w%. Torrefied biomass C6H8O3 +moisture~3%. Energy carrier Fuel suitable for. gasification combustion. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 3. 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Objective and working plan Objective: To develop a model of biomass torrefaction able to predict both solid and volatile matter versus operating conditions and biomass composition.. Approach: summative contribution of the main biomass constituents ∆mbiomass = ∆mcellulose . %cellulose + ∆mlignin . %lignin + ∆mhemicellulose . %hemicellulose. Working plan: Lab-scale experiments: Thermogravimetric analysis Torrefaction unit TORNADE Kinetic modelling 21st European Biomass Conference , Copenhagen – June, 7th 2013. 4.

(3) 1. Introduction 2. Materials and method3. Experimental results 4. Modelling 5. Conclusion. Biomass: beech Drying at 105°C Milling <200 µm Ash (0.6%) Extractives (3.0%). 43.3%. Lignin. Cellulose. 22.0%. Avicel. Extracted from beech. 31.1%. Xylan Extracted from beech (Representative of hemicellulose) 5. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 1. Introduction 2. Materials and method3. Experimental results 4. Modelling 5. Conclusion. TGA: solid mass loss kinetics Setaram TG-DSC 111 Electronic balance Alumina tubes Carrier gas N2. Study in chemical regime Water. Crucibles. Error between replicates<1%. Water. Carrier gas N2. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 6.

(4) 1. Introduction 2. Materials and method3. Experimental results 4. Modelling 5. Conclusion. TORNADE: volatile matter production Torrefaction. Study in chemical regime. Gas and condensable Condensable species analyzer species collection. P. Mass balance : 99 - 104%. FTIR. M. (150 C) Temperature. N2. N2. Gas flowrate. 1 NL.min-1. Sample mass. 100-200 mg. Sample 0°C. Furnace. 220;250;280;300°C. Gas atmosphere -65°C. Reactor 7. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Kinetics of solid mass loss 100. 80 60 40 20. Beech Lignin. Cellulose Xylan. 250°C. 0. g / mass g in itia l (% ) Solid (wmf%). Solid (wmf%) g / mass g in itia l (% ). 100. 80 60 40 20. Beech Lignin. Cellulose Xylan. 280°C. 0. 0. 25. 50. 75. 100. 125. 150. 175. 0. 25. 50. Time (min) Time (min). 75. 100. 125. 150. 175. Time (min) Time (min). Lignin: smooth and continuous mass loss Xylan: fast and (very) sharp mass loss Cellulose: – T ≤ 250°C: nearly no mass loss – T ≥ 280°C: slow mass loss then the highest rate 21st European Biomass Conference , Copenhagen – June, 7th 2013. 8.

(5) 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Gas and condensable species yields yield (wmf%) gMass / g initial (%). 40. 220°C. Beech. 250°C. 30. 280°C. 20. 300°C. 10. ac. ac. ic. ic. rm Fo. Ac. Fo. rm. id. id. er at. et. hy al. de. W. ra. de. l. l rf u. no. Fu. M. et. ha. CO. 2. CO. 0. Main species: H2O, formaldehyde, acetic acid, CO2 Other species: CO, formic acid, methanol, furfural 9. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. 220°C. 40. Mass yield (wmf%) g / g initial (%). Cellulose. 250°C 280°C. 30. 300°C. 20 10 0. 220°C. 40. 280°C 300°C. 20 10. id. id. er. Fo. rm. ic. ac. ac. at W. ic et. Fo. Ac. rm. al. de. hy. rf u. ra. de. l. l no. Fu. et M. Lignin. 250°C. Each species not produced by all constituents. 280°C. 30. CO. 2. rm Fo. 220°C. 40. ha. ac i ic. ic et Ac. al. Fo. rm. d. id. er. ac. at. hy de. W. ra. de. l. ol. r fu. an et h. M. Fu. 2 CO. CO. 0. Formic acid only produced by xylan torrefaction. 300°C. 20 10. Acetic acid not produced by cellulose/lignin/xylan id. id. er. Fo. rm. ic. ac. ac. Ac. et. ic. at W. Comes from acetyl groups of hemicellulose Removed during extraction of xylan. Fo. rm. al. de. hy. rf u. ra. de. l. l Fu. no ha et. M. 2. CO. 0. CO. g / g initial (%) Mass yield (wmf%). Xylan. 250°C. 30. CO. Mass yield (wmf%) g / g initial (%). Gas and condensable species yields. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 10.

(6) 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Description with additive law? 220°C. 80. 250°C. Solid g / g mass in itia(wmf%) l (% ). 100. 60. 280°C. 40. 300°C Beech. 20. Additive law. 0 0. 25. 50. 75. 100. 125. 150. 175. Time (min) Time (min). Interactions between beech constituents from 280°C?. Correct at T ≤ 250°C Not correct at T ≥ 280°C. 11. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Mix of beech constituents Cellulose - Lignin. Cellulose - Xylan 100. 250°C 80 60. 280°C. 40. 300°C Mix (Cellulose – Lignin). 20. Additive law. 0 0. 25. 50. Solid g / g mass in itia(wmf%) l (% ). Solid g / gmass in itia(wmf%) l (% ). 100. 80. 250°C. 60. 280°C. 40. Mix (Cellulose – Xylan). 20. Additive law. 0. 75. 100. 125. 150. 0. 175. 25. Solid g / gmass in itial(wmf%) (% ). Xylan - Lignin 250°C 280°C 300°C. 60 40. Mix (Xylan – Lignin) Additive law. 0 0. 25. 50. 75. 100. Time (min) Time (min). 75. 100. 125. 150. 175. Interactions from 280°C between:. 80. 20. 50. Time(min) (min) Time. Time (min) Time (min) 100. 300°C. 125. 150. 175. Cellulose and Lignin Cellulose and Xylan Discrepancies linked with cellulose decomposition Decrease of the mix reaction rate. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 12.

(7) 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Interactions origin? One hypothesis Solid mass (wmf%). 100 80 60 40 20 Cellulose. Lignin. Xylan. 280°C. 0 0. 25. 50. 75. 100. 125. 150. 175. Time (min) Temps (min). Degradation of Xylan and Lignin:. Ramification of Cellulose by Rxylan Rlignin. Production of numerous radicals Rxylan Rlignin and/then of volatile matter Depolymerization of Cellulose. + Rxylan. Rxylan. + Rlignin. Rlignin. + 13. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Interactions origin? One hypothesis Solid mass (wmf%). 100 80 60. Interactions. 40 Cellulose with interactions. 20. Cellulose. Lignin. Xylan. 280°C. 125. 150. 0 0. 25. 50. 75. 100. 175. Time (min) Temps (min). Degradation of Xylan and Lignin:. Ramification of Cellulose by Rxylan Rlignin. Production of numerous radicals Rxylan Rlignin and/then of volatile matter Depolymerization of Cellulose. + Rxylan. Rxylan. + Rlignin. Rlignin. Decrease of Cellulose decomposition rate + 21st European Biomass Conference , Copenhagen – June, 7th 2013. 14.

(8) 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Kinetic model of biomass torrefaction Biomass composition. Cellulose. Lignin. Hemicellulose Xylan. Acetyl groups. 15. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Constituents sub-models Model of Di Blasi (1997) – 2 steps – 2 parallel reactions – First-order kinetics – Arrhenius law Yield of volatile species. kv1 A. V1 k1. B. V2. kv2 k2. C.  − Eai  k ij = A iexp   RT  Ysj = α s1j R V1 + α s2j R V2. α s1j = α s2j. Cellulose. H2O, CO2, CO, formaldehyde, furfural. Lignin. H2O, CO2, CO, formaldehyde, furfural, methanol. Xylan. H2O, CO2, CO, formaldehyde, methanol, formic acid. Acetyl groups. Acetic acid. Determination of the parameters Least-squares minimization method 21st European Biomass Conference June, 7th 2013 Di Blasi C, Lanzetta M (1997) Journal, Copenhagen of Analytical –and Applied Pyrolysis, 40-41:287.. 16.

(9) 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Kinetic model of biomass torrefaction. Anc Eaic αsc. Cellulose. kil Eail αsl. Lignin. Hemicellulose kix Eaix αsx. Empirical factor tN. Xylan. Acetyl groups. kix Eaix αsx. Additivity. Torrefied solid. CO, CO2, H2O, acetic acid, formaldehyde, formic acid, furfural, methanol 17. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Model validation 220°C. Rendement Solid mass(%m) (wmf%). Torrefaction model. Biomass composition. 250°C 280°C 300°C Experiment. Model. Time (min) Satisfactory results: – Prediction of solid yield with a difference < 3% – Estimation of 8 volatile species yields with differences < 40% 21st European Biomass Conference , Copenhagen – June, 7th 2013. 18.

(10) 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. Conclusion How to model torrefaction vs T, residence time and biomass composition ? Sum of the main biomass constituents: – Correct when T ≤ 250°C – Interactions between cellulose and other compounds when T ≥ 280°C Empirical factor on cellulose decomposition rate Satisfactory prediction of: – Solid mass loss – The 8 main volatile species yields: H2O, formaldehyde, acetic acid, CO2, CO, formic acid, methanol, furfural Not produced by all constituents. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 19. 1. Introduction 2. Materials and method 3. Experimental results 4. Modelling 5. Conclusion. What’s next? Confirm the interactions origin. Apply the model to other biomasses. Extend the model to other volatile species of interest for chemical industry. 21st European Biomass Conference , Copenhagen – June, 7th 2013. 20.

(11) If you have any questions or want more details, please contact: capucine.dupont@cea.fr 21st European Biomass Conference , Copenhagen – June, 7th 2013. 21.

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