Biogas Conversionh using Dielectric Barrier Discharge Non-thermal Plasma

Transcription

1 Biogas Conversionh using Dielectric Barrier Discharge Non-thermal Plasma Yifei Sun*, Xiaolan Zeng, Zhijie Wang, Lina Liu School of Chemistry and Environment, Beihang University July. 3 rd, 2015

2 Outline 1. Background 2. Materials and Methods - Pyrolysis process of biomass wastes - Reforming of biogas using dielectric barrier discharge non-thermal plasma - Analytical methods 3. Results and Discussion -Pyrolytic characteristics of biomass wastes at different temperatures - Influence of discharge powers on the reforming products - Influence of gas components on the reforming products 4. Conclusion

3 Outline 1. Background 2. Materials and Methods - Pyrolysis process of biomass wastes - Reforming of biogas using dielectric barrier discharge non-thermal plasma - Analytical methods 3. Results and Discussion -Pyrolytic characteristics of biomass wastes at different temperatures - Influence of discharge powers on the reforming products - Influence of gas components on the reforming products 4. Conclusion

4 Energy status 1. Background Energy Crisis Fossil energy: non-renewable energy Facing serious energy crisis (from World Energy Council, London, 2004) oil gas coal 40 years 60 years 200 years environmental crisis BG:Biomass Gasification Source Change of Hydrogen in 21 Century Gasification technology would be the primary pattern of biomass energy conversion. Moreover, hydrogen production by gasification would be the main pathway to obtain renewable energy. Industrial civilization relying on fossil energy is just a scene of the history of human civilization. The time of renewable energy is a kind of historical regression and necessity.

5 Industrial wastes of China 1. Background Municipal solid wastes (10 8 ton) 2,00 1,80 1,60 1,40 1,20 1,00 0,80 0,60 0,40 0,20 0,00 Biomass energy: renewable energy MSW IW 36,00 31,00 26,00 21,00 16,00 11,00 6,00 1,00-4,00 Industrial solid wastes (10 8 ton) Industrial biomass waste xylogen cellulose hemicellulose Annual increment of MSW and IW in China In 2013, the IW reached 3.3 billion tons in China. Products of biomass pyrolysis gas tar char

6 eforming pyrolysis products by plasma 1. Background Gaseous products of biomass pyrolysis: H 2,CO,CH 4 and CO 2 ; Micromolecular hydrocarbon; Macromolecular hydrocarbon. Reforming of pyrolysis gas Catalytic reforming Steam reforming Partial oxidation Plasma reforming Plasma reforming Reforming pyrolysis products by plasma Free radical and ionic reaction Higher conversion of CH 4 Progress of modern reactor design Lower energy consumption of non-thermal plasma

7 Outline 1. Background 2. Materials and Methods - Pyrolysis process of biomass wastes - Reforming of biogas using dielectric barrier discharge non-thermal plasma - Analytical methods 3. Results and Discussion -Pyrolytic characteristics of biomass wastes at different temperatures - Influence of discharge powers on the reforming products - Influence of gas components on the reforming products 4. Conclusion

8 Pyrolysis process of biomass wastes 2. Materials and Methods Pyrolysis setup of Biomass wastes Biomass AC N 2 Tube furnace Air pocket Mass flowmeter Ice-water bath Methyl alcohol flowmeter Experimental conditions Pyrolysis temperatures:400,500,600,700,800 ºC

9 Pyrolysis process of biomass wastes 2. Materials and Methods Reforming setup by plasma Plasma reactor Methyl alcohol N 2 Mass flowmeter Gas mixer High-voltage electrode Ice-water bath GC H 2 CO CH 4 CO 2 Feed gas Carrier gas:n 2,50 ml/min Component 1: CH 4 and CO 2, CH 4 : CO 2 = 1:1, 1:2, 2:1 Component 2: CH 4, CO 2 and CO, CH 4 : CO 2 : CO= 1:1:3, 1:2:2, 2:1:2 Component 3: CH 4, CO 2 and H 2, CH 4 : CO 2 : H 2 = 1:1:1,1:2:1, 2:2:1

10 Analytical methods 2. Materials and Methods experimental material pine sawdust Grinding and selecting the pine sawdust with appropriate particle size, Drying at 105 ºC for 24h before use, 4g for each experiment dosage uv(x10,000) Chromatogram Test targets Total amounts of gas products CO 2, CH 4, CO, H Analysis and test test methods gas flowmeter GC-TCD (Carboxen-1010 PLOT) min Target gas H 2 N 2 CO CH 4 CO retention time /min

11 Evaluation index of plasma reforming 2. Materials and Methods The calculation methods of conversion of CO 2 and CH 4 (X), selectivity of H 2 and CO (S) and carbon balance (B) is as follows: [CO 2] in -[CO X (CO )(%) = [CO 2] in 2 out 2 [CH4] in -[CH4 ] out X (CH )(%) = [CH4 ] in [CO] out S(CO)(%) = [CH 4] in + [CO 2] in -[CH 4] S(H )(%) 4 = 0.5 [H2 ] out [CH 4] in -[CH 4] 2 out B(C) = 1- [CO] ] out + [CH 4] out + [CO 2] [CH 4] in + [CO 2] in out 100% 100% - [CO 2] 100% out out 100% Where [X] in represents the flow of target gas in the air inflow, whereas, [X] out represents the flow of target gas in the air out. B(C) represents the ratio of conversion of CH 4 and CO 2 in the air inflow to non-co carbon (containing tar, char, and et.al)

12 Outline 1. Background 2. Materials and Methods - Pyrolysis process of biomass wastes - Reforming of biogas using dielectric barrier discharge non-thermal plasma - Analytical methods 3. Results and Discussion -Pyrolytic characteristics of biomass wastes at different temperatures - Influence of discharge powers on the reforming products - Influence of gas components on the reforming products 4. Conclusion

13 Results and discussion Pyrolysis of biomass wastes Pyrolytic characteristics of biomass wastes at different temperatures n=3, RSD <10% Temperature ( ) H 2 +CO (mol%) H 2 /CO (mol/mol) With temperature increasing to 800 ºC, the ratio of H 2 +CO and CH 4 among total gas products increased to mol% and mol%, respectively. Moreover, the ratio of H 2 /CO increased to 0.34.

14 Temperature Influence of discharge powers 3. Results and discussion Reforming CH 4 and CO 2 (a) (c) (b) (d) Conversion of CH 4 and CO 2 and selectivity of CO and H 2 both increased with the addition of discharge powers.

15 Influence of discharge powers Reforming CH 4, CO 2 and CO (a) 3. Results and discussion (c) (b) (d) The addition of CO into CH 4 and CO 2 in the plasma reforming process would inhibit the conversion of CO 2 (b), however, it had tiny influence on the conversion of CH 4 (a). It can be concluded that CO 2 might have the unique transformation paths, however, CH 4 might have nonunique transformation paths.

16 Influence of discharge powers 3. Results and discussion Reforming CH 4, CO 2 and CO The total reforming reaction is as follows: CH 4 + CO2 CO + H2 It can be concluded from the results that CO 2 might have the unique transformation paths, however, CH 4 might have non-unique transformation paths. CO 2 + e CO + O +e CH + e CH +H + e 4 3 CH + e CH +H + e CH + e CH +H +H + e 4 2 CH + e C + 2H + e 4 2

17 Influence of discharge powers 3. Results and discussion Reforming CH 4, CO 2 and H 2 (a) (c) (b) (d) The addition of H 2 into CH 4 and CO 2 would inhibit the selectivity of H 2 (c) and improve the The selectivity of CO decreased with the increase of discharge powers (d). It indicates that selectivity of CO (d). However, it still had tiny influence on the conversion of CH 4 (b). This result CO may react to form other products at higher powers. confirms the consumption of non-unique transformation paths of CH 4.

18 Influence of gas components 3. Results and discussion Reforming gas of different components (a) (c) (b) (d) The Adding conversion CO in the of CH reaction 4 increased gas, the with selectivity the discharge of H 2 power increases increasing, (c), andwhereas the selectivity the of addition CO shows of CO little and change H 2 had (d); tiny Adding influence H 2 in on the reaction conversion gas, of the CHselectivity 4 (a). of H 2 decreases (c), and The the conversion selectivity of of CO CO 2 decreased increases through (d). adding both CO and H 2 in the reaction gas (b).

19 Carbon balance 3. Results and discussion (a) (c) (b) (d) B(c) increased with the increase of discharge power. It means that it will produce more non-co products at higher discharge power.

20 Outline 1. Background 2. Materials and Methods - Pyrolysis process of biomass wastes - Reforming of biogas using dielectric barrier discharge non-thermal plasma - Analytical methods 3. Results and Discussion -Pyrolytic characteristics of biomass wastes at different temperatures - Influence of discharge powers on the reforming products - Influence of gas components on the reforming products 4. Conclusion

21 4. Conclusion 4. Conclusion The increase of pyrolysis temperature of biomass contributes to the formation of syngas (H 2 +CO) ; The conversion of CH 4 is mainly influenced by the discharge power, whereas, the addition of CO and H 2 will reduce the conversion of CO 2 ; Adding CO in the reaction gas, the selectivity of H 2 increases, and the selectivity of CO shows little change; Adding H 2 in the reaction gas, the selectivity of H 2 decreases, and the selectivity of CO increases. The decomposition of CO 2 has the only path; however, the decomposition of CH 4 might have multiple paths. Free radical reaction is the main reaction mechanism. With the discharge power increasing, it will produce H 2 O, carbon deposition and even some organic liquids.

22 Acknowledgement Grands Supported: 4. Conclusion Nation Natural Science Foundation of China (Project No ), National Science and Technology Support Program of China (Project No. 2010BAC66B04), Royal Academy of Engineering, UK(12/13RECI051), Plasma-catalysis for the conversion of tar from biomass gasification into clean fuels Group Students

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