Hydrothermal Carbonization of the Wet Fraction from Mixed Municipal Solid Waste: A Fuel and Structural Analysis of Hydrochars

Maciej Śliz, Klaudia Czerwińska, Aneta Magdziarz, Lidia Lombardi and Małgorzata Wilk
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Maciej Śliz: Department of Heat Engineering and Environment Protection, AGH University of Science and Technology, Mickiewicza 30 Av., 30-059 Krakow, Poland
Klaudia Czerwińska: Department of Heat Engineering and Environment Protection, AGH University of Science and Technology, Mickiewicza 30 Av., 30-059 Krakow, Poland
Aneta Magdziarz: Department of Heat Engineering and Environment Protection, AGH University of Science and Technology, Mickiewicza 30 Av., 30-059 Krakow, Poland
Lidia Lombardi: Niccolò Cusano University, Via Don Carlo Gnocchi 3, 00166 Rome, Italy
Małgorzata Wilk: Department of Heat Engineering and Environment Protection, AGH University of Science and Technology, Mickiewicza 30 Av., 30-059 Krakow, Poland

Energies, 2022, vol. 15, issue 18, 1-15

Abstract: One of the by-products of a mechanical-biological waste treatment plant is the under-sieve fraction, which requires separation prior to further processing of municipal mixed waste. This stream usually follows the fate of landfilling. Instead, it could be introduced to the hydrothermal carbonization (HTC) process to improve its fuel properties and become solid recovered fuel. The organic fraction and high moisture content (approximately 26%) of under-sieve fraction are favorable properties for the HTC process. In this study, hydrochars, the solid product of HTC, were produced at 200 and 220 °C with residence times of 1, 4, and 8 h. The main aim of this investigation was to establish the influence of different process parameters on hydrochars’ fuel properties. Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were employed in the analyses. The results confirmed the positive effects of hydrothermal carbonization on the under-sieve fraction of municipal mixed waste properties. The ignition temperature increased from 247 °C to 288 °C and burnout temperature decreased to 443 °C from 489 °C after hydrothermal carbonization, causing a shorter combustion process. The determined key combustion parameters were: S = 12.4 × 10 ?8 %·min ?2 ·°C ?3 , H f = 1174.9 °C and Di = 0.0075%·min ?3 , which in comparison to USF decreased by 44%, increased by 33%, and decreased by 29%, respectively, and became closer to those of coal. Furthermore, the identified structural changes indicate that hydrochars could be successfully used in energy production. The most promising results were found for hydrochar produced at 220 °C for 1 h, leading to a better combustion performance and providing a more stable and a less violent flame.

Keywords: hydrothermal carbonization; municipal solid waste; TGA; FTIR; SEM-EDS (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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