Effect of Segregation on the Reaction Rate of Sewage Sludge Pyrolysis in a Bubbling Fluidized Bed
The evolution of the pyrolysis of sewage sludge in a fixed and a fluidized bed was analyzed using a novel measuring technique. This original measuring technique consists of installing the whole reactor over a precision scale, capable of measuring the mass of the complete reactor with enough precision to detect the mass released by the sewage sludge sample during its pyrolysis. The inert conditions required for the pyrolysis process were obtained supplying the bed with a nitrogen flowrate, and the bed temperature was adjusted to either 500 ºC or 600 ºC using a group of three electric resistors. The sewage sludge sample was supplied through the top of the bed in a batch of 10 g. The measurement of the mass released by the sewage sludge sample was employed to determine the evolution of the reaction rate during the pyrolysis, the total amount of volatile matter released, and the pyrolysis time. The pyrolysis tests of sewage sludge in the fluidized bed were conducted using two different bed materials of the same size but different densities: silica sand and sepiolite particles. The higher density of silica sand particles induces a flotsam behavior for the sewage sludge particles which move close to the bed surface. In contrast, the lower density of sepiolite produces a neutrally-buoyant behavior for the sewage sludge particles, which shows a proper circulation throughout the whole bed in this case. The analysis of the evolution of the pyrolysis process in both fluidized beds show that the pyrolysis is faster when buoyancy effects are negligible, i.e. in the bed conformed by sepiolite particles. Moreover, sepiolite was found to show an absorbent capability for the volatile matter released during the pyrolysis of sewage sludge.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1131968Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 677
 A. Demirbas, M. F. Demirbas, Importance of algae oil as a source of biodiesel. Energy Conversion and Management, vol. 52, pp. 163–170, 2011.
 I. Fonts, M. Azuara, G. Gea, M. B. J. Murillo, Study of the pyrolysis liquids obtained from different sewage sludge. Journal of Analytical and Applied Pyrolysis, vol. 85, pp. 184–91, 2009.
 P. Manara, A. Zabaniotou, Towards sewage sludge based biofuels via thermochemical conversion – A review. Renewable and Sustainable Energy Reviews, vol. 16, pp. 2566–2582, 2012.
 W. Rulkens, Sewage sludge as a biomass resource for the production of energy: overview and assessment of the various options. Energy & Fuels, vol. 22, pp. 9–15, 2008.
 D. Fytili, A. Zabaniotou, Utilization of sewage sludge in EU application of old and new methods – A review. Renewable and Sustainable Energy Reviews, vol. 12, pp. 116–40, 2008.
 H. Fan, H. Zhou, J. Wang, Pyrolysis of municipal sewage sludges in a slowly heating and gas sweeping fixed-bed reactor. Energy Conversion and Management, vol. 88, pp. 1151–1158, 2014.
 G. Liu, H. Song, J. Wua, Thermogravimetric study and kinetic analysis of dried industrial sludge pyrolysis. Waste Management, vol. 41, pp. 128–133, 2015.
 B. Leckner, Developments in fluidized bed conversion of solid fuels. Thermal Science, vol. 20, pp. S1–S18, 2016.
 B. Leckner, Fluidized bed combustion: Mixing and pollutant limitation. Progress in Energy Combustion Science, vol. 24, pp. 31–61, 1998.
 A. Gómez-Barea, B. Leckner, Modeling of biomass gasification in fluidized beds. Progress in Energy and Combustion Science, vol. 36, pp. 444–509, 2010.
 I. N. S. Winaya, T. Shimizu, D. Yamada, A new method to evaluate horizontal solid dispersion in a bubbling fluidized bed. Powder Technology, vol. 178, pp. 173–178, 2007.
 G. M. Rios, K. Dang Tran, H. Masson, Free object motion in a gas fluidized bed. Chemical Engineering Communications, vol. 47, pp. 247–272, 1986.
 A. Soria-Verdugo, L. M. García-Gutiérrez, N. García-Hernando, U. Ruiz-Rivas, Buoyancy effects on objects moving in a bubbling fluidized bed. Chemical Engineering Science, vol. 66, pp. 2833–2841, 2011.
 M. C. Samolada, A. A. Zabaniotou, Comparative assessment of municipal sewage sludge incineration, gasification and pyrolysis for a sustainable sludge-to energy management in Greece. Waste Management, vol. 34, pp. 411–420, 2014.
 E. S. Park, B. S. Kang, J. S. Kim, Recovery of oils with high caloric value and low contaminant content by pyrolysis of digested and dried sewage sludge containing polymer flocculants. Energy & Fuels, vol. 22, pp. 1335-1340, 2008.
 H. J. Park, H. S. Heo, Y. K. Park, J. H. Yim, J. K. Jeon, J. Park, C. Ryu, S. S. Kim, Clean bio-oil production from fast pyrolysis of sewage sludge: Effects of reaction conditions and metal oxide catalysts. Bioresource Technology, vol. 101, pp. 83-85, 2010.
 R. O. Arazo, D. A. D. Genuino, M. D. G. de Luna, S. C. Capareda, Bio-oil production from dry sewage sludge by fast pyrolysis in an electrically-heated fluidized bed reactor. Sustainable Environmental Research, vol. 27, pp. 7-14, 2017.
 Y. Sun, B. S. Jin, Y. J. Huang, W. Zuo, J. Q. Jia, Y. Y. Wang, Distribution and characteristics of products from pyrolysis of sewage sludge. Advanced Materials Research, vol. 726, pp. 2885-2893, 2013.
 Y. Sun, B. Jin, W. Wu, W. Zuo, Y. Zhang, Y. Zhang, Y. Huang, Effects of temperature and composite alumina on pyrolysis of sewage sludge. Journal of Environmental Sciences, vol. 30, pp. 1-8, 2015.
 P. C. Carman, Fluid flow through granular beds. Transactions of the Institute of Chemical Engineers, vol. 15, pp. 150-166, 1937.
 J. Sánchez-Prieto, A. Soria-Verdugo, J. V. Briongos, D. Santana, The effect of temperature on the distributor design in bubbling fluidized beds. Powder Technology, vol. 261, pp. 176–184, 2014.
 S. A. Scott, J. S. Dennis, J. F. Davidson, A. N. Hayhurst, Thermogravimetric measurements of the kinetics of pyrolysis of dried sewage sludge. Fuel, vol. 85, pp. 1248-53, 2006.
 A. Soria-Verdugo, N. Garcia-Hernando, L. M. Garcia-Gutierrez, U. Ruiz-Rivas, Analysis of biomass and sewage sludge devolatilization using the distributed activation energy model. Energy Conversion and Management, vol. 65, pp. 239-244, 2013.
 K. Jayaraman, I. Gökalp, Pyrolysis, combustion and gasification characteristics of miscanthus and sewage sludge. Energy Conversion and Management, vol. 89, pp. 83-91, 2015.
 A. Soria-Verdugo, E. Goos, N. Garcia-Hernando, Effect of the number of TGA curves employed on the biomass pyrolysis kinetics results obtained using the Distributed Activation Energy Model. Fuel Processing Technology, vol. 134, pp. 360-371, 2015.
 A. Soria-Verdugo, E. Goos, J. Arrieta-Sanagustín, N. Garcia-Hernando, Modeling of the pyrolysis of biomass under parabolic and exponential temperature increases using the Distributed Activation Energy Model. Energy Conversion and Management, vol. 118, pp. 223-230, 2016.
 A. Soria-Verdugo, E. Goos, A. Morato-Godino, N. Garcia-Hernando, U. Riedel. Pyrolysis of biofuels of the future: Sewage sludge and microalgae – Thermogravimetric analysis and modelling of the pyrolysis under different temperature conditions. Energy Conversion and Management, vol. 138, pp. 261-272, 2016.
 A. Soria-Verdugo, A. Morato-Godino, L.M. Garcia-Gutierrez, N. García-Hernando, Pyrolysis of sewage sludge in a bubbling fluidized bed: determination of the reaction rate. In 12th International Conference on Fluidized Bed Technology, Krakow (Poland), May 2017.