Smouldering Fuel Processing, Emission Flammability, and Carbon Footprint

Chen, Yuying

Smouldering Fuel Processing, Emission Flammability, and Carbon Footprint

Chen, Yuying

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Publication Type:: Thesis
Issue Date:: 2023

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Field	Value	Language
dc.contributor.author	Chen, Yuying
dc.date.accessioned	2024-04-23T00:58:02Z
dc.date.available	2024-04-23T00:58:02Z
dc.date.issued	2023
dc.identifier.uri	http://hdl.handle.net/10453/178231
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_US.UTF-8
dc.description.abstract	Smouldering is an emerging method for biowaste removal, which has demonstrated many attractive advantages. However, as smouldering is an in-completed combustion, it tends to release many toxic emissions, like CO, CH4, and volatile organic compounds (VOCs), limiting its further promotion and application. Therefore, this thesis proposes and thoroughly investigates a novel combustion method for biowaste removal that uses a self-sustained flame co-existing with smouldering to clean the toxic smouldering emissions. Firstly, it is verified through experiments that the smouldering emission of biomass can be piloted to sustain a flame and the flame can co-exist with smouldering combustion. The critical smouldering flux of wood waste for maintaining a stable flame remains constant at 10-12 g/m2∙s. To reach such a smouldering flux, the minimum opposed airflow velocity required is 6 mm/s. Then, the effects of fuel property and smouldering direction (forward or opposed) on the critical conditions are investigated. It is found that an equivalent critical mass flux of flammable gases required for igniting the smouldering emissions is 0.5 g/m2∙s, regardless of the fuel type. Additionally, it is easier for the flame to remove more emissions from opposed smouldering which is recommended for the proposed biowaste removal process. The efficiency of the pollution mitigation of the applied flame is demonstrated by significantly lower CO and VOCs emissions (with ΔCO/ΔCO2<0.05 and ΔVOCs/ΔCO2<0.0005) after purification. Finally, four smouldering-based biowaste processing strategies: (a) full smouldering, (b) partial smouldering, (c) full smouldering with a flame, and (d) partial smouldering with a flame, are proposed and evaluated. The results show that full smouldering achieves the highest removal efficiency but generates significant greenhouse and toxic gases, while partial smouldering effectively generates stable biochar (with 0.2<H:C<0.5, 0.2<O:C<0.3, and R50=0.6), sequestering over 30 % carbon. And, a smaller airflow rate is recommended for the partial smouldering strategy to fix more carbon. It is also proved that the equivalent GHG from the four proposed processing strategies are all smaller than that from the conventional landfilling treatment. This work enriches strategies for the clean treatment of smouldering emissions and promotes an energy-efficient and environmentally friendly method for biowaste removal.	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/178231/1/thesis.pdf
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	© 2023 Yuying Chen
dc.rights	au.edu.uts.lib/cph
dc.title	Smouldering Fuel Processing, Emission Flammability, and Carbon Footprint	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

Smouldering is an emerging method for biowaste removal, which has demonstrated many attractive advantages. However, as smouldering is an in-completed combustion, it tends to release many toxic emissions, like CO, CH4, and volatile organic compounds (VOCs), limiting its further promotion and application. Therefore, this thesis proposes and thoroughly investigates a novel combustion method for biowaste removal that uses a self-sustained flame co-existing with smouldering to clean the toxic smouldering emissions. Firstly, it is verified through experiments that the smouldering emission of biomass can be piloted to sustain a flame and the flame can co-exist with smouldering combustion. The critical smouldering flux of wood waste for maintaining a stable flame remains constant at 10-12 g/m2∙s. To reach such a smouldering flux, the minimum opposed airflow velocity required is 6 mm/s. Then, the effects of fuel property and smouldering direction (forward or opposed) on the critical conditions are investigated. It is found that an equivalent critical mass flux of flammable gases required for igniting the smouldering emissions is 0.5 g/m2∙s, regardless of the fuel type. Additionally, it is easier for the flame to remove more emissions from opposed smouldering which is recommended for the proposed biowaste removal process. The efficiency of the pollution mitigation of the applied flame is demonstrated by significantly lower CO and VOCs emissions (with ΔCO/ΔCO2<0.05 and ΔVOCs/ΔCO2<0.0005) after purification. Finally, four smouldering-based biowaste processing strategies: (a) full smouldering, (b) partial smouldering, (c) full smouldering with a flame, and (d) partial smouldering with a flame, are proposed and evaluated. The results show that full smouldering achieves the highest removal efficiency but generates significant greenhouse and toxic gases, while partial smouldering effectively generates stable biochar (with 0.2

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