Jean-louis Dirion Olivier Bonnefoy Patricia Arlabosse Alexandre Govin Sylvain Salvador Stu tudy of f self lf-heating phenomenon of f torrefied wood in in contact wit ith oxygen octobre 1 st st 2014 PhD. th thes esis is started oct 2014 Brieuc Evangelista Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC How to to ach achie ieve th the energetic ic tr transi sition ? From fossil to renewable energy sources Increase biomasses energetic valorization Ther Th ermochemic ical Biochemical rou oute route (Combustion, co-combustion, gazeification, pyrolysis...) (Hydrolysis, fermentation, distillation...) Wea eak fu fuel el properties es Higher gr Hig grade fu fuel el Pretreatments - High water content - Lower water content - Grinding - Low energy density - Higher energy density - AFEX - Poor grindability - Better grindability - Torr orrefactio ion - Poor decay resistancy - Better decay resistancy - … 2 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC Development of of large scale torrefaction market expected to to the decade to to come (Th Thrän et et al al. 2016 2016) Safety issue Science beyond self-heating phenomenon: He Heat diss dissipation He Heat gen eneration Highly size dependent Exothermic reaction(s) Temperature Thermal runaway Self-ig Self ignit ition Not othing Self Self-heating Time 3 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC Ind Industria ial sa safety ty iss ssue (Esbjerg, Danemark, 1998) 70 000 tonnes de pellets de bois The larger the system the more sensitive to self-heating and self- ignition (Franck-Kamenetskii 1969) Phenomenon observed with torrefied wood (Verhoeff et al. 2012) 4 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC Th Thesis is sci scientific ap approach The larger the system Industrial issues Understanding and control of physicochemical phenomenon involved Multi-scale approach mg g kg Powder Particle Fixed bed particules Reaction only Diffusion + reaction Advection + diffusion + reaction 5 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC Th Thesis is sci scientific ap approach The larger the system Industrial issues Understanding and control of physicochemical phenomenon involved Multi-scale approach mg g kg Powder Particle Fixed bed particules Reaction only Diffusion + reaction Advection + diffusion + reaction Today’s program: how to desc scrib ibe th the reaction kin kinetic between oxygen an and tor orrefied wood? 6 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives Presentation overv rview a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC 1. 1. In Introduction a. Social context b. Scientific context 2. Bib 2. iblio liographic resu sults 3. Experimental par 3. arts a. Protocol presentation b. Calorimetry, TGA and DSC results 4. 4. Con onclusion & perspectives 7 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC What doe oes th the lit literature teach us us ? Coal industry: long time issue Reaction called « low – temperature oxidation » Related to mining and handling hazards General findings CO and CO 2 are the Chemisorption of O 2 main gaseous product creation of surface oxides (Gethner 1985) Thermal decomposition (Vastola et al. 1964) of surface oxides (Marinov 1977) Complex reaction Reactive sites: carbon atoms mecanism simplifies limiting reagent (Wang et al. 2003) (Teng & Hsieh 1999) 8 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC Clas lassical protocol* Raw material: beech wood powder (<80 µm) Temperature Inert atmosphere: nitrogen Oxidative atmosphere: O 2 + N 2 Torrefaction Drying Oxidative step Time 0 Two severities of torrefaction Mild (240°C, 20 min), yield 86 +/- 1% 𝑍𝑗𝑓𝑚𝑒 = 𝑛 𝑢𝑝𝑠𝑠𝑓𝑔𝑗𝑓𝑒 𝑛 𝑒𝑠𝑧 Severe (290°C, 3 min), yield 68 +/- 2% Oxidative step temperature range [°C] & experimental devices 40 70 100 140 150 225 Calorimeter TGA* TGA* DSC* 9 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC Cal alorim imetric ic resu esult lts, [40 40 ; 70 70] °C Specificity of the protocol Torrefaction ex situ Heat flow stabilized 10 hours under nitrogen flush then 12 hours under air flush Mildly torrefied Severely torrefied Maximum heat flow followed by an exponential decay • Highest number of free reactive site at time 0 and consumption Increase with torrefaction severity • Higher propensity to self-heat and self-ignite 10 10 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC Why doe oes th the heat flo flow not ot go go bac ack to to zero ? Diffusion ? = (5 µ𝑛) 2 𝐸 𝑃 2 𝑓𝑔𝑔 ~ 𝑀 𝑑 ² Effective diffusion coefficient: = 10 −16 𝑛 2 . 𝑡 −1 𝜐 𝑑 10ℎ Experimental artefact ? Equilibrium between pyrolysis reactions and oxygen adsorption (Kaji et al. 1987) Small ll heat of of physis isorption in involv lved 11 11 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
1. 1. Introduction 2. 2. Bib ibliography 3. 3. Exp Experimental al res esults 4. 4. Conclusi sion & pe persp spectives a. Social cont ntext a. Prot otoc ocol ol pres esent entation on b. Sciien entific cont ntext b. Calor orimet etry, TGA GA & DSC TGA resu sults, [100 100 ; 140 140] °C Mildly torrefied Severely torrefied Small amount of oxygen adsorbed on the wood surface Increase with severity of torrefaction • Higher number of free reactive sites → Increase of carbon content with torrefaction severity 12 12 Institut Mines-Télécom Institut Mines-Télécom 13 july 2017
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