Optimization of process variables for briquetting of biochar from corn stover

Abstract

Instead of compressing biomass into briquettes, this study considers the compression of biochar. Densification is necessary for biochar to increase bulk density for convenience of handling, transportation, and storage. Response surface methodology was employed, and briquetting of biochar from corn stover was carried out in this study to investigate the effects of moisture content (at levels of 16, 17.6, 20, 22.4, and 24%), pressure (at levels of 21.5, 25, 30, 35, and 38.5 MPa), and residence time (at levels of 4, 6.4, 10, 13.6, and 16 s), on crushing resistance, dimensional stability of briquettes, and specific energy consumption of briquetting. The results showed that the effects of the variables on each evaluation index were significant (P < 0.01), the influence order was obtained, and the regression models are set up. The optimum condition for the briquetting process was moisture content of 18.5%, pressure of 38.5 MPa, and residence time of 4 s, giving mean values of the briquette crushing resistance of 49.9 N, dimensional stability of 93.8%, and specific energy consumption of briquetting of 4.41 MJ/t, respectively. The errors between the predicted values and the experimental values are all less than 5%.

Parameters optimization for compressing a mixture of decomposed rice straw and biochar into a seedling-raising mat

“…Biochar is the pyrolysis product of biomass such as crop straw, which can improve soil fertility and physicochemical properties of straw seedling substrate, and is conducive to the growth of crops (Meng et al 2011;Carter et al 2013;Nieto et al 2016;Gao et al 2017;Jiao et al 2020). Wen et.…”