Abstract
Miscanthus was treated by hydrothermal carbonisation in a 2-L batch reactor at 200 °C and 250 °C with residence times ranging between 0 and 24 h to understand the impact of residence time has on the resulting bio-coal combustion chemistry. Increasing the residence time results in dehydration of the bio-coal and increased repolymerisation; however, temperature has the greatest influence on bio-coal properties. After 24 h at 200 °C, bio-coal has similar properties to that of the 250 °C + 0 h bio-coal. After 1 h at 250 °C, the cellulose present in the raw biomass appears to be largely removed. The removal of cellulose and the associated dehydration and repolymerisation results in bio-coal having a ‘coal like’ combustion profile, which exhibits a decreasing reactivity with increasing residence time. At 200 °C + 0 h, 75% of the alkali metal is removed, increasing to 86% with increasing residence time. Further extraction is seen at 250 °C. Phosphorus and sulphur appear to undergo substantial extraction at 200 °C + 0 h but then are reincorporated with increasing residence time. The calcium content increases in the bio-coal with increasing residence time at 200 °C but then reduces after 1 h at 250 °C. Increasing temperature and residence time has been shown to decrease the fuels’ fouling and slagging propensity.
Highlights
Hydrothermal carbonisation (HTC) is a thermal conversion process capable of producing sustainable carbonaceous products from biomasses and waste materials
The results show for both temperatures that increasing the residence time increases the carbon density, reduces the oxygen density and increases the energy density of the resulting bio-coal, with the highest energy density being observed for HTC
Miscanthus was hydrothermally carbonised at 200 ◦ C and 250 ◦ C with varying residence times from 0 to 24 h to better understand the influence residence time has on the inorganic and combustion chemistry of bio-coal derived from lignocellulosic biomasses
Summary
Hydrothermal carbonisation (HTC) is a thermal conversion process capable of producing sustainable carbonaceous products from biomasses and waste materials. The reaction rates and products from HTC are governed to a large extent by reaction temperature, which governs the extent of hydrolysis, dehydration and polymerisation reactions [9,10] and the onset of the degradation of key components such as cellulose, hemicellulose and lignin [10,11,12,13]. Residence time is another important parameter, with studies in the literature ranging from less than 5 min up to several days. This is important as several authors have suggested that HTC may reduce the slagging, fouling and corrosion propensity of the resulting bio-coal, as demonstrated through either alkali metal or ash reductions [2,13,14,15,16,17,18,19,20,21,22]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
