Simon Tradler, Anna Stadler, Werner Baumgartner,
"Hydrothermal Carbonization: a Decentralized and Discontinuous Technology to Convert Organic Food Waste into High Quality Hydrochar"
, in DAKAM Publishing, in BIOENG'15, Seite(n) 207-215, 11-2015, ISBN: 978-605-9207-15-7
Hydrothermal Carbonization: a Decentralized and Discontinuous Technology to Convert Organic Food Waste into High Quality Hydrochar
Sprache des Titels:
In the field of bioenergy, the main focus lies on the conversion of biomass into high quality products like biogas, soil improver and biochar. Unfortunately, modern biomass conversion processes still face numerous problems. To gain economic efficiency, biomass plants like anaerobic digesters need to be designed large-scaled and run continuously. Other technologies like pyrolysis, a dry-thermal process, need to pre-treat the biomass. A further general issue is inhomogeneous feedstock like organic food waste. In this work, we establish a new method that converts inhomogeneous organic food waste into high quality hydrochar. The hydrothermal carbonization (HTC) is a thermo-chemical process that mimics the natural coal formation. A closed reactor, i.e. an autoclave, is filled with wet biomass and treated at 180-250°C for several hours. The final product consists of a solid residue called hydrothermal carbon, a liquid and a gas phase, where the solid carbon constitutes about 40% of the total output. The process has exothermic characteristics, i.e. it releases up to a third of the energy stored in carbohydrates throughout the dehydration process. Here, we processed different compositions of feedstock, based on the analysis of food waste from several restaurants. Also, we tried to define thresholds for certain products in the food waste, for example animal fats and proteins. We examined the input-output stream, such as the solid, liquid and the gas phase, to define a controllable, automatic process. To determine the quality of the hydrochar, we examined the carbon with scanning electron microscope (SEM). Also, we did elemental analysis of the carbon to determine the heating value. Taken together, this process not only deals with inhomogeneous and wet biomass but also can run discontinuously and decentralized, since the plant size can be adapted depending on the requirements.