The hydrothermal carbonization process (HTC) is commonly used as a method for the thermal conversion of feedstock characterized by a high moisture level. The most popular materials are biomass, sewage sludge and food waste. One of the product of the HTC process is hydrochar, which might serve as a substitute for non-renewable fossil fuels. It is a solid material characterized by a high content of carbon. The properties of hydrochar depends mainly on the parameters of the HTC process: temperature and residence time. In this research the feedstock used in the HTC process was agricultural digestate obtained from biogas plant. Digestate is a by-product of the fermentation process which occurs during biogas production. In this study digestate was mixed with water and subjected to the HTC process at 190 and 200°C and residence time 0.5 – 2 h. Then the physical and chemical properties of hydrochar were analysed to assess its fuel properties. Based on the results, it was determined that higher temperature and longer residence time affect higher carbon content and calorific value in hydrochars.
Keywords
- Biomass
- Hydrothermal carbonization
- Hydrochar
- Process water
- Biofuels
Acknowledgment
This research was funded by the Ministry of Science and Higher Education, Poland [AGH grant no. 16.16.110.663/501.00-110000-10000]. Research project was partly supported by program „Excellence Initiative – Research University” for the AGH University of Krakow, Action D21.