University of Twente Student Theses


Supercritical water gasification of biomass: modeling of char formation and a socio-economic study

Polanco Pacheco, Christian Andrés (2017) Supercritical water gasification of biomass: modeling of char formation and a socio-economic study.

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Abstract:Supercritical water gasification is an exciting technology and a more convenient choice against anaerobic digestion for the recycling of wet streams of organic biomass. This technology does not need drying as pre-treatment and also takes considerably less residence time, minutes or even seconds depending on the conditions. In this process, highly pressurized water is in contact with organic biomass which is instantly decomposed into gaseous products but also into unwanted side-products known as char. This char is a cracking product, which decreases the gasification efficiency, causing plugging in the heat exchanger or deposits on the reactor walls which leads to fouling. This study investigates the char formation problem in supercritical gasification through a Computational Fluid Dynamics (CFD) numerical model using commercial software ANSYS Fluent with glucose as biomass model compound. The model includes complete thermo-physical properties at supercritical conditions for all species involved, chemical reactions and kinetic data from lab-scale experimental results for the formation of char and gaseous products. The numerical simulations were carried in laminar and turbulent flow. The results were replicated and show good agreement with experimental data. Therefore, the developed numerical model is considered as successful. It can mimic the char formation behavior under the influence of changing temperature and give valuable insights for future reactor and process optimization. In the last part of the thesis, a socio-economic assessment of the technology under a Dutch context is presented. Results showed that a supercritical water gasification process design could be economically feasible and that has fascinating perspectives as a tailor-made waste management solution for specific niches, where it can further mature and consolidate.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Programme:Sustainable Energy Technology MSc (60443)
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