Bench-Scale Fluidized-Bed Pyrolysis of Switchgrass for Bio-Oil Production

Abstract

The U.S. biomass initiative is counting on lignocellulosic conversion to boost the quantities of biofuels currently produced from starches in order to achieve much needed energy security in the future. However, with current challenges in fermentation of lignocellulosic material to ethanol, other methods of converting biomass to usable energy have received consideration nationally. One thermochemical technique, fast pyrolysis, is being considered by the Agricultural Research Service (ARS) researchers of the USDA for processing energy crops such as switchgrass and other agricultural residues, e.g., barley hulls and alfalfa stems for bio-oil (pyrolysis oil or pyrolysis liquids) production. A 2.5 kg/h biomass fast pyrolyzer has been developed at ARS and tested for switchgrass conversion. The unit has provided useful data such as energy requirements and product yields that can be used as design parameters for larger systems based on the processing of perennial energy crops. Bio-oil yields greater than 60% by mass have been demonstrated for switchgrass, with energy conversion efficiencies ranging from 52 to 81%. The results show that char yielded would suffice in providing all the energy required for the endothermic pyrolysis reaction process. The composition of the noncondensable gas produced has been initially characterized. Initial mass and energy balances have been calculated based on this system, yielding useful parameters for future economic and design studies.

Regional differences in the economic feasibility of advanced biorefineries: Fast pyrolysis and hydroprocessing

“…The results are presented in Table 2. Switchgrass (Agblevor and Besler, 1996;Agblevor et al, 1995;Boateng et al, 2007;Fahmi et al, 2008) (Anon, 2008), and the ENR 20-city Construction Cost Index (Anon, 2012a Gulf Coast basis. The DOD's area cost factors are adjusted to place them on the same baseline basis by using the average area cost factor for Louisiana as unity.…”

Switchgrass for bioethanol and other value-added applications: A review

“…Pyrolysis of Cave-in-Rock switchgrass to produce bio-oil was conducted by Boateng et al (2007) using a fluidized bed system. The study reported bio-oil yields greater than 60% by mass with energy conversion efficiencies ranging from 52% to 81%.…”

Characterization of Biochar from Switchgrass Carbonization

“…Imam and Capareda [10] reported increases in switchgrass biochar heating value (HV), carbon content, and surface area and decreases in biochar yield, hydrogen, and nitrogen contents with increasing pyrolysis temperatures (400, 500 and 600 °C). Boateng et al [4] discussed the potential use of pyrolysis biochar as fuel to supply part of the thermal energy necessary during switchgrass pyrolysis. However, they noted that the high ash content of the char (25% by mass) would be problematic in further thermal conversion, i.e., combustion.…”