Mathematical Modeling of Fast Biomass Pyrolysis and Bio-Oil Formation. Note II: Secondary Gas-Phase Reactions and Bio-Oil Formation

Abstract

This paper summarizes the research activities done at Politecnico di Milano in the field of the detailed kinetic modeling of fast pyrolysis of biomass to produce bio-oil. Note I of this work already discussed biomass characterization and the multistep pyrolysis mechanisms of reference species. The model is able to provide a detailed composition of pyrolysis products and char residue. Different critical steps are involved in this multicomponent, multiphase and multiscale problem. The first complexity relies in biomass characterization. Then, fast pyrolysis process involves detailed kinetic mechanisms, first in the solid phase for the biomass pyrolysis, then in the gas-phase for the secondary reactions of released products. The complexity of these kinetic mechanisms requires strong simplifications, thus chemical lumping procedures are extensively applied. Successive or secondary gas phase reactions of gas and tar components released during the pyrolysis process complement the kinetic model, together with the heterogeneous reactions of residual char. The modeling of fast pyrolysis process requires a comprehensive description of the coupled transport and kinetic processes, both at the particle and the reactor scale. A few examples and comparisons with experimental data validate the reliability of the overall model. Finally, the composition and physical properties of the pyrolysis bio-oil are also discussed, with emphasis on combustion and pollutant emissions.

A rigorous process modeling methodology for biomass fast pyrolysis with an entrained‐flow reactor

“…[6] Each phase has its own set of coupled mass, momentum, and energy balance equations, described in detail by Humbird et al [8] This model makes use of the updated biomass decomposition kinetics of Ranzi et al, [9] which incorporate a more detailed evaluation of biomass composition and pyrolysis products. Like the original model, [8] it does not consider secondary gas phase reactions (eg, Ranzi et al [11] ) which can be important at temperatures as low as 400 C. [12] These could be added for a more complete description in future work. The reactions and their corresponding rate constants (using Humbird et al's notation), k n ,…”

Measuring biomass fast pyrolysis kinetics: State of the art

“…The most applied semi‐detailed mechanism for complete biomass pyrolysis is that developed by Ranzi et al (Table ; Debiagi et al, ; Faravelli et al, ; Ranzi et al, , , , ) This mechanism consists of individual decomposition schemes for cellulose, hemicellulose, and lignin. The mechanism is versatile as variations in feedstock composition can be accounted for.…”

“…The most applied semi-detailed mechanism for complete biomass pyrolysis is that developed by Ranzi et al (Table 9; Debiagi et al, 2015;Faravelli et al, 2010;Ranzi et al, 2008Ranzi et al, , 2012Ranzi et al, , 2017aRanzi et al, , 2017b This mechanism consists of individual…”

“…Besides, these studies can also help in designing a suitable catalyst to improve the selectivity towards desired products (Butler et al, ; Li et al, ). Numerous studies have been performed over the years to decode the kinetic mechanisms of biomass fast pyrolysis (Agarwal, Dauenhauer, Huber, & Auerbach, ; Bai et al, ; Bai & Brown, ; Banyasz, Li, Lyons‐Hart, & Shafer, ; Bradbury, Sakai, & Shafizadeh, ; Branca, Di Blasi, Mango, & Hrablay, ; Broido & Nelson, ; Choi et al, ; Chu, Subrahmanyam, & Huber, ; Custodis, Hemberger, Ma, & van Bokhoven, ; Debiagi et al, ; Faravelli, Frassoldati, Migliavacca, & Ranzi, ; Gai et al, ; Huang, Liu, Tong, Li, & Wu, ; Huang, Liu, Wei, Huang, & Li, ; Kawamoto, Murayama, & Saka, ; Kawamoto & Saka, ; Khachatryan, Xu, Wu, Pechagin, & Asatryan, ; Kim, Bai, & Brown, ; Lou, Wu, & Lyu, ; Mayes & Broadbelt, ; Mayes, Nolte, Beckham, Shanks, & Broadbelt, ; Mettler, Mushrif, et al, 2012; Miller & Bellan, ; Norinaga, Shoji, Kudo, & Hayashi, ; Nowakowska, Herbinet, Dufour, & Glaude, ; Patwardhan, Dalluge, Shanks, & Brown, ; Patwardhan, Satrio, Brown, & Shanks, ; Piskorz, Majerski, Radlein, Vladars‐Usas, & Scott, ; Piskorz, Radlein, & Scott, ; Ranzi et al, , ; Ranzi, Debiagi, & Frassoldati, , ; Ronsse, Dalluge, Prins, & Brown, ; Scheer et al, ; Scheer, Mukarakate, Robichaud, Nimlos, & Ellison, ; Shafizadeh & Fu, ; Shen & Gu, ; Shen, Gu, & Bridgwater, ; Shen, Xiao, Gu, & Luo, ; Varhegyi, Jakab, & Antal, ; Vasiliou et al, ; Vinu & Broadbelt, ; Wang, Ru, Lin, & Luo, ; Werner, Pommer, & Broström, ; Zhang, Li, Yang, & Blasiak, ; Zhang, Nolte, & Shanks, ; Zhou, Li, Mabon, & Broadbelt, ; Zhou, Nolte, Mayes, Shanks, & Broadbelt,…”

Modeling for Pyrolysis of Solid Biomass

“…Ranzi et al [12] discussed in this paper a comprehensive and unifying mathematical model that describes the chemistry of fast biomass pyrolysis. Emphasis is given to the multicomponent, multiphase, multiscale nature of this problem, together with the several simplifications for both the gas and solid phase kinetic mechanisms.…”