Combustion kinetics of hydrochar from cow-manure digestate via thermogravimetric analysis and peak deconvolution

Hydrothermal carbonization (HTC) can convert wet biomass into hydrochar (HC), a solid carbonaceous material exploitable as fuel. In this study, HTC was applied to anaerobic digestate from cow manure. HCs obtained at three HTC temperatures (180, 220, 250 degrees C) were characterized in detail and their combustion behavior was investigated by thermogravimetric analysis (TGA) coupled with peak deconvolution. Increasing HTC temperatures increased the fixed carbon content (17.9-20.7%), the ash content (27.2-32.5%) and the calorific value (14.3-18.2 MJ/kg), while decreased the hydrogen (5.01-4.54%) and oxygen content (24.09-12.35%) of HCs. DTG profiles peak deconvolution unveils the presence of five major components in the HCs. HCs combustion kinetics were studied applying the KAS method. Average apparent activation energy values of 100, 88, 67 kJ mol-1 were obtained for HC180, HC220, HC250, respectively. HTC at 250 degrees C produced the HC with the best fuel characteristics.

Automated summary

This study applied hydrothermal carbonization (HTC) to anaerobic digestate from cow manure, converting it into hydrochar (HC) with different characteristics at varying temperatures. The results showed that increasing HTC temperatures led to higher fixed carbon content, ash content, and calorific value of the HC, while reducing the hydrogen and oxygen content. The study also identified five major components in the HC and analyzed their combustion kinetics.