Impact of ammonia fiber expansion (AFEX) pretreatment on energy consumption during drying, grinding, and pelletization of corn stover

Journal Article · Fri Jan 08 00:00:00 EST 2016 · Drying Technology

DOI:https://doi.org/10.1080/07373937.2015.1112809· OSTI ID:1357243

Bonner, Ian Jeffery ^[1]; Thompson, David N. ^[1]; Plummer, Mitchell ^[1]; Dee, Matthew ^[1]; Tumuluru, Jaya Shankar ^[1]; Pace, David ^[1]; Teymouri, Farzaneh ^[1]; Campbell, Timothy ^[1]; Bals, Bryan ^[1]

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1. Idaho National Lab. (INL), Idaho Falls, ID (United States)

Pretreatment and densification of biomass can increase the viability of bioenergy production by providing a feedstock that is readily hydrolyzed and able to be transported greater distances. Ammonia Fiber Expansion (AFEX) is one such method targeted for use at distributed depots to create a value-added and densified feedstock for bioenergy use. However, the pretreatment process results in a high-moisture material that must be dried, further size reduced, and pelletized; all of which are energy intensive processes. This work quantifies the energy consumption required to dry, grind, and densify AFEX pretreated corn stover compared to non-pretreated stover and explores the potential of reduced drying as a means to conserve energy. The purpose of this work is to understand whether material property changes resulting from AFEX pretreatment influence the material performance in downstream formatting operations. Material properties, heat balance equations, and a rotary drum dryer model were used to model a commercial scale rotary drum dryer for AFEX pretreated corn stover, showing the potential to reduce dryer energy consumption by up to 36% compared to non-pretreated corn stover. Laboratory measured grinding and pelleting energies were both very sensitive to material moisture content. Overall, the total energy required for drying, grinding, and pelleting amounts to a savings of up to 20 kWh/dry ton for the AFEX pretreated material when dried to a low moisture content, equating to up to 0.55 /kg savings for gas and electricity. Grinding and pelleting of high moisture AFEX pretreated stover was shown to be more costly than the savings collected through reduced drying. Furthermore, while the energy and cost savings shown here are modest, the results help to highlight operational challenges and opportunities for continued improvement.

• Research Organization: Idaho National Lab., Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• Grant/Contract Number: AC07-05ID14517
• OSTI ID: 1357243
• Report Number(s): INL/JOU-15-35699
• Journal Information: Drying Technology, Vol. 34, Issue 11; ISSN 0737-3937
• Publisher: Taylor & Francis
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
AFEX
biomass
corn stover
rotary dryer
energy analysis
heat and mass transfer
mathematical modeling