Proof-of-Concept of High-Pressure Torrefaction for Improvement of Pelletized Biomass Fuel Properties and Process Cost Reduction

• Published in: Energies (Basel) Vol. 13; no. 18; p. 4790
• Main Authors: Matyjewicz, Bartosz, Świechowski, Kacper, Koziel, Jacek A., Białowiec, Andrzej
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2020
• Subjects: Atmospheric pressure; Biomass; Biomass energy; Calorific value; Carbon; Densification; Drying; Energy consumption; Experiments; grinding; Moisture content; Nuclear fuels; pellet; pressure torrefaction; Pyrolysis; renewable energy sources; Sulfur content; thermogravimetric analysis; Poland
• ISSN: 1996-1073; 1996-1073
• DOI: 10.3390/en13184790

This paper provides a comprehensive description of the new approach to biomass torrefaction under high-pressure conditions. A new type of laboratory-scale high-pressure reactor was designed and built. The aim of the study was to compare the high-pressure torrefaction with conventional near atmospheric pressure torrefaction. Specifically, we investigated the torrefaction process influence on the fuel properties of wooden-pellet for two different pressure regimes up to 15 bar. All torrefaction processes were conducted at 300 °C, at 30 min of residence time. The initial analysis of the increased pressure impact on the torrefaction parameters: mass yields, energy densification ratio, energy yield, process energy consumption, the proximate analysis, high heating value, and energy needed to grind torrefied pellets was completed. The results show that high-pressure torrefaction needed up to six percent less energy, whereas energy densification in the pellet was ~12% higher compared to conventional torrefaction. The presence of pressure during torrefaction did not have an impact on the energy required for pellet grinding (p < 0.05).