Conventional and autothermal pyrolysis of corn stover: Overcoming the processing challenges of high-ash agricultural residues

Polin, Joseph P.; Carr, Howard D.; Whitmer, Lysle E.; Smith, Ryan G.; Brown, Robert C.

doi:10.1016/j.jaap.2019.104679

Title: Conventional and autothermal pyrolysis of corn stover: Overcoming the processing challenges of high-ash agricultural residues

Abstract

The high ash content of agricultural residues and other kinds of herbaceous biomass makes it a challenging feedstock for fast pyrolysis to bio-oil. Using corn stover as a representative feedstock, this study investigates fast pyrolysis of high ash, herbaceous biomass in a pilot-scale fluidized bed reactor using both conventional, nitrogen-blown and autothermal, air-blown operation. Initial efforts to pyrolyze corn stover were challenged by bed fouling, which prevented steady reactor operation. Substitution of coarser bed material allowed operation at higher superficial velocities, which promoted attrition and elutriation of recalcitrant biochar particles from the reactor. This resulted in dramatic improvement in stable reactor operation for both conventional and autothermal pyrolysis with bio-oil yields among the highest reported for pyrolysis of corn stover. The oxygen-to-biomass equivalence ratio required for autothermal operation was 6.8%. Autothermal operation also resulted in significant process intensification, increasing corn stover throughput from 7.8 kg hr^–1 to 21.9 kg hr^–1 for this 8.9 cm diameter reactor. Air-blown, autothermal operation did not significantly reduce bio-oil yield despite the presence of partial oxidation reactions. In conclusion, carbon balances indicate carbon yields of biochar and aqueous, bio-oil light ends decreased by 18.5% and 4.7%, respectively, during autothermal pyrolysis compared to conventional pyrolysis whilemore »« less

Authors:

Polin, Joseph P. ^[1]; Carr, Howard D. ^[1]; Whitmer, Lysle E. ^[1]; Smith, Ryan G. ^[1]; Brown, Robert C. ^[1]

Iowa State Univ., Ames, IA (United States)

Publication Date:: Mon Aug 12 00:00:00 EDT 2019

Research Org.:: RAPID Manufacturing Institute, New York, NY (United States)

Sponsoring Org.:: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Manufacturing Office

OSTI Identifier:: 1642386

Grant/Contract Number:: EE0007888

Resource Type:: Accepted Manuscript

Journal Name:: Journal of Analytical and Applied Pyrolysis

Additional Journal Information:: Journal Volume: 143; Journal Issue: C; Journal ID: ISSN 0165-2370

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 09 BIOMASS FUELS; Corn stover; Autothermal; Fast pyrolysis; Fluidized bed; Process intensification

Citation Formats


                    Polin, Joseph P., Carr, Howard D., Whitmer, Lysle E., Smith, Ryan G., and Brown, Robert C. Conventional and autothermal pyrolysis of corn stover: Overcoming the processing challenges of high-ash agricultural residues.  United States: N. p., 2019. 
Web.  doi:10.1016/j.jaap.2019.104679.

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                    Polin, Joseph P., Carr, Howard D., Whitmer, Lysle E., Smith, Ryan G., & Brown, Robert C. Conventional and autothermal pyrolysis of corn stover: Overcoming the processing challenges of high-ash agricultural residues.  United States.  https://doi.org/10.1016/j.jaap.2019.104679

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                    Polin, Joseph P., Carr, Howard D., Whitmer, Lysle E., Smith, Ryan G., and Brown, Robert C. Mon .  
"Conventional and autothermal pyrolysis of corn stover: Overcoming the processing challenges of high-ash agricultural residues".  United States.  https://doi.org/10.1016/j.jaap.2019.104679.  https://www.osti.gov/servlets/purl/1642386.

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@article{osti_1642386,

  title        = {Conventional and autothermal pyrolysis of corn stover: Overcoming the processing challenges of high-ash agricultural residues},

  author       = {Polin, Joseph P. and Carr, Howard D. and Whitmer, Lysle E. and Smith, Ryan G. and Brown, Robert C.},

  abstractNote = {The high ash content of agricultural residues and other kinds of herbaceous biomass makes it a challenging feedstock for fast pyrolysis to bio-oil. Using corn stover as a representative feedstock, this study investigates fast pyrolysis of high ash, herbaceous biomass in a pilot-scale fluidized bed reactor using both conventional, nitrogen-blown and autothermal, air-blown operation. Initial efforts to pyrolyze corn stover were challenged by bed fouling, which prevented steady reactor operation. Substitution of coarser bed material allowed operation at higher superficial velocities, which promoted attrition and elutriation of recalcitrant biochar particles from the reactor. This resulted in dramatic improvement in stable reactor operation for both conventional and autothermal pyrolysis with bio-oil yields among the highest reported for pyrolysis of corn stover. The oxygen-to-biomass equivalence ratio required for autothermal operation was 6.8%. Autothermal operation also resulted in significant process intensification, increasing corn stover throughput from 7.8 kg hr–1 to 21.9 kg hr–1 for this 8.9 cm diameter reactor. Air-blown, autothermal operation did not significantly reduce bio-oil yield despite the presence of partial oxidation reactions. In conclusion, carbon balances indicate carbon yields of biochar and aqueous, bio-oil light ends decreased by 18.5% and 4.7%, respectively, during autothermal pyrolysis compared to conventional pyrolysis while the more valuable, organic-rich heavy ends of the bio-oil were essentially preserved.},

  doi          = {10.1016/j.jaap.2019.104679},

  journal      = {Journal of Analytical and Applied Pyrolysis},

  number       = C,

  volume       = 143,

  place        = {United States},

  year         = {Mon Aug 12 00:00:00 EDT 2019},

  month        = {Mon Aug 12 00:00:00 EDT 2019}

}

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Table 1: Properties of corn stover biomass*

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