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Comparative energy and techno-economic analyses of two different configurations for hydrothermal carbonization of yard waste
- Akbari, Maryam, Oyedun, Adetoyese Olajire, Kumar, Amit
- Bioresource technology reports 2019 v.7 pp. 100210
- biocoal, biomass, energy, heat, heat exchangers, hydrochars, hydrothermal carbonization, models, production costs, separators, steam, yard wastes
- Hydrothermal carbonization (HTC) includes conversion of wet biomass to hydrochar, a coal-like product, eliminating the need for biomass pre-drying. There has been limited focus on the techno-economic assessment of the HTC process in the literature. In this study, techno-economic models were developed to assess the economics of bio-coal production from yard waste for two different HTC plant configurations. In configuration A, heat is recovered by steam using several flash separators while in configuration B special heat exchangers are used. Process models were developed for the two configurations and then further used to estimate bio-coal production costs. The bio-coal cost and the net energy ratio (NER, or ratio of energy output to the energy input in the system) indicate that configuration A is preferable in terms of energy (NER of 5.2 versus 1.4 for configuration B) but less desired economically because it costs 3.3 $/GJ more than configuration B.