Use of Torrefaction and Solvent Extraction To Produce Ash-less Biomass as a Solid Fuel Feedstock for Co-firing

Abstract

As a result of the characteristics of biomass, biomass exploitation as a secondary fuel feedstock in co-firing is only technically and economically acceptable in the range of 5−10% (w/w). In this study, torrefaction and solvent extraction as biomass pretreatments were conducted to address feedstock limitations, making a larger share of biomass for co-firing feasible. The physical and chemical characteristics of the solvent-extracted biomass were investigated using proximate analysis, ultimate analysis, thermogravimetric analysis, and Fourier transform infrared spectroscopy. Biomass torrefied at 200, 250, 270, 300, and 330 °C was extracted by nonpolar organic solvent 1-methylnaphthalene at 350 °C for 1 h to produce ash-less biomass (extracted biomass). A dry, raw, woody biomass was also extracted under the same conditions to see the effect of torrefaction on the characteristics of extracted biomass and residue biomass. The result shows that solvent extraction was effective in producing ashless biomass, with less than 0.1 wt % (dry basis) ash content remaining in the extracted fraction. It was also found that the torrefaction temperature had an effect on the extracted biomass yield and slightly influenced the physical and chemical properties of the extracted biomass. The unique properties of the extracted biomass make it possible to use for other purposes, namely, as high-value functional materials.

Torrefaction and Degradative Solvent Extraction As Means of Processing Rice Husk Waste

“…This could have been caused by polycondensation reactions experienced by the hemicellulose and lignin that may occur under 200 °C and become more severe as the temperature increases. The reaction could induce the formation of a stable cross-linked carbohydrate polymer that leads to the formation of char, making the sample hard to extract . Up to 200 °C, the polycondensation reaction during torrefaction accounted for a decrease in the EB yield of the T200 extraction.…”

“…Extraction of T330 had a significantly lower yield of EB (12 wt %, db) and much higher yield of RB (51.9 wt %, db) compared to the other samples. This may have been caused by the severe cellulose degradation and initiated pyrolysis during torrefaction above 300 °C. , Torrefaction at this temperature generates more unextractable fraction (char) and explains the significantly lower and higher yield of EB and RB, respectively …”

“…The solvent extraction process was carried out at 300 °C using a small-batch autoclave reactor (Ilshin Autoclave) for 1 h after purging the reactor with N 2 . The detailed reactor configuration was discussed in previous publication . The extraction process was done by mixing and heating 30 g of each biomass sample with 1-MN with a weight ratio of 1:9.…”

“…The detailed reactor configuration was discussed in previous publication. 16 The extraction process was done by mixing and heating 30 g of each biomass sample with 1-MN with a weight ratio of 1:9. The slurry was then mixed with an agitator at 60 rpm.…”

“…Torrefaction is known to be advantageous in high-scale biomass processing as it enables the biomass to be stored and transported easily before any further conversions. Hidayat et al 16 tried to investigate the effect of torrefaction prior to solvent extraction on woody biomass, which has low ash content. Agro-industrial waste, however, is mostly grass-based biomass, which has a much higher ash content.…”