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

Authors

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, Mika

Thesis advisor

Kohl, Thomas

Keywords

supercritical water gasification, algae, conceptual process design, synthetic natural gas, hydrogen

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Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-201501301790

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[dipl] Insinööritieteiden korkeakoulu / ENG