Development of an optimized conceptual plant design for supercritical water gasification of biomass
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Journal Title
Journal ISSN
Volume Title
Insinööritieteiden korkeakoulu |
Master's thesis
Date
2015-01-26
Department
Major/Subject
Energy Technology
Mcode
K3007
Degree programme
Energia- ja LVI-tekniikan koulutusohjelma
Language
en
Pages
138+22
Series
Abstract
Supercritical water gasification, SCWG as a mean for hydrothermal processing of biomass, has illustrated the potential to counter technical barriers that continue to face the wide deployment of biomass based energy systems. The advantageous varying chemical and physical properties of water around the pseudo critical point allow for energetic efficient recovery of the organic constituents in solid biomass. This research provides a systematic approach to fill the knowledge gap for upscaling the process from laboratory bench scale to commercial demonstration. The thermodynamic constraints and drivers of the SCWG reactor were analyzed with an equilibrium model developed on Matlab(R) that depicts the solid biomass transformation to synthetic gases. In addition to, a reactor simulation model on Aspen plus(R) was developed to assess the influence of the different heterogeneous structures of biomass as well as the overall energetic conversion of the process. Based on parametric studies, design decision variables were used to select optimal process conditions as well as an appropriate feedstock to maximize the energetic valorization into synthetic natural gas, SNG and hydrogen. Conceptual plant flowsheets for SCWG of spirulina algae were developed on Aspen plus(R) for both SNG and hydrogen production. The advantageous reactor system configurations are integrated in the process layout with consequential gas purification, mechanical power extraction and downstream indirect production to maximize the energetic polygeneration of chemical fuels, power and thermal heat. The design and synthesis for the process blocks, components and equipment was based on operational data for referenced pilot or commercial units. Heat integration studies based on the pinch analysis method were conducted for the conceptual designs. The minimum process utility demands were computed, and different energy recovery scenarios as well as alternative design configurations for optimal heat recovery were assessed. The thermodynamic performance of designs were evaluated by the overall process energetic and fuel equivalent efficiencies.Description
Supervisor
Järvinen, MikaThesis advisor
Kohl, ThomasKeywords
supercritical water gasification, algae, conceptual process design, synthetic natural gas, hydrogen