Title: Improving bamboo’s fuel and storage properties with a net energy export through torrefaction paired with catalytic oxidation

Abstract

Using torrefied char, also known as biocoal, as solid fuel provides an opportunity to introduce a new, sustainable feedstock into the energy market. The goal of this study was to investigate how torrefaction improves the energy content and the grindability of Malaysian bamboo when conducted at various temperatures, and how these can be applied in an industrial scale torrefaction facility. In this regard, the Malaysian bamboo was torrefied at 250, 270, and 290 °C at a 1 hr residence time. The physiochemical properties of the products were characterized in terms of elemental, proximate, and compositional analyses. The higher heating value (HHV), combustion characteristics, and the grindability of the products were also investigated. In addition, the torrefied gas species were analyzed during the torrefaction experiment. Finally, the experimental findings were implemented into a 100,000 tonne per year capacity torrefaction plant to investigate its heat and mass balance and understand how a catalytic oxidation system can efficiently utilize the torrefaction gaseous products. The results showed that, when the torrefaction was conducted at 290 °C, the elemental carbon increased from 47 wt% to 63 wt%. Similarly, the HHV increased from 17.8 to 25.6 MJ/kg. The combustion behavior of all the products appears tomore » show three distinct combustion zones, with Zone I (25–200 °C) comprised mainly the evaporation of moisture, Zone II (200–400 °C) comprised mainly of the combustion of volatile matter, and Zone III (400–700 °C) comprised mainly of the combustion of fixed carbon. The grindability study showed that the torrefied bamboo at 290 °C required 2.7 times less time to mill through a 6 mm screen compared to the raw bamboo. Meanwhile, the energy required to grind the raw bamboo was about 938 kWh/tonne while it was only 111 kWh/tonne for the torrefied bamboo at 290 °C. A case study showed that catalytic oxidation can convert nearly 100% of the chemical energy contained in the torrefaction gas into usable thermal energy. In case of 270 °C operating temperature, the plant has 15.59 GJ/hr excess energy beyond what the process needs.« less

Authors:

Saha, Nepu  ^[1];

• Search DOE PAGES for author "Saha, Nepu"
• Search DOE PAGES for ORCID "0000-0002-2819-5714"

Fillerup, Eric P. ^[1]; Thomas, Brad J. ^[1]; Pilgrim, Corey David  ^[1];

• Search DOE PAGES for author "Pilgrim, Corey David"
• Search DOE PAGES for ORCID "0000-0001-9381-1256"

Causer, Thomas P. ^[2]; Herren, Dan ^[2]; Klinger, Jordan Lee  ^[1]

• Search DOE PAGES for author "Klinger, Jordan Lee"
• Search DOE PAGES for ORCID "0000-0003-4004-9864"

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+ Show Author Affiliations

1. Idaho National Lab. (INL), Idaho Falls, ID (United States)
2. Advanced Torrefaction Systems, LLC, Kirkwood, MO (United States)

Publication Date:

Thu Mar 24 00:00:00 EDT 2022

Research Org.:

Idaho National Laboratory (INL), Idaho Falls, ID (United States)

Sponsoring Org.:

USDOE Office of Nuclear Energy (NE); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Transportation Office. Bioenergy Technologies Office

OSTI Identifier:

1903027

Report Number(s):

INL/JOU-21-65213-Rev000
Journal ID: ISSN 1385-8947; TRN: US2311252

Grant/Contract Number:  

AC07-05ID14517

Resource Type:

Accepted Manuscript

Journal Name:

Chemical Engineering Journal

Additional Journal Information:

Journal Volume: 440; Journal Issue: C; Journal ID: ISSN 1385-8947

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

09 BIOMASS FUELS; Torrefaction; Higher heating value; Combustion characteristics; Grinding energy; Heat and mass balance; Catalytic oxidation