Design optimization of a fixed bed biomass gasifier of a two stage incinerator

Waste wood, a renewable energy source is used as feedstock for Universiti Teknologi Malaysia’s newly-developed two-stage incinerator system. The research goals are to optimize the operation of the thermal system, to improve its combustion efficiency and to minimize its pollutants formation. The work...

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Main Author:	Mat Tokit, Ernie
Format:	Thesis
Language:	English
Published:	2008
Subjects:	TJ Mechanical engineering and machinery
Online Access:	http://eprints.utm.my/id/eprint/12196/1/ErnieMatTokitMFKM2008.pdf
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id	my-utm-ep.12196
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spelling	my-utm-ep.121962018-07-23T05:45:37Z Design optimization of a fixed bed biomass gasifier of a two stage incinerator 2008-10 Mat Tokit, Ernie TJ Mechanical engineering and machinery Waste wood, a renewable energy source is used as feedstock for Universiti Teknologi Malaysia’s newly-developed two-stage incinerator system. The research goals are to optimize the operation of the thermal system, to improve its combustion efficiency and to minimize its pollutants formation. The work focuses on one of its components, i.e. the primary chamber which comprises of a large updraft fixed-bed chamber, measuring 187.5cm in height and 194.5 cm in diameter respectively. During experimental work, the primary chamber is fed in batches of the processed feedstock while the air for combustion is metered through an eight air nozzle supply system, incorporated at the lower side of the tapered chamber. The feedstock will undergo four different processes; drying, devolatilisation, gasification and combustion. The combustion process is evaluated with the variation of fuel’s moisture content, i.e. set at 17%, 31%, and 40% respectively. The initial experimental work indicates that the temperature and oxide of nitrogen (NO) concentration are decreased with the increase of the moisture in the fuel. Furthermore, the concentration of carbon monoxide (CO) increases with the variation of this operating parameter. However the change for carbon dioxide (CO2) and oxygen (O2) concentrations are only around 1% with the variation of this operating parameter. For optimum operating condition, where the gasification efficiency is 95.53%, the moisture content of the fuel is best set at 17%; giving outlet operating temperature of 550oC and exhaust gas concentrations with 1213 ppm of CO, 6% of CO2, 66 ppm of NO and 14% of O2 respectively. In parallel to the experimental work, a computational fluid dynamics software is used to simulate the performance of the primary chamber at optimum operating condition. This technique provides detail insights on the dynamics of flow and the combustion behavior that occur in the reference chamber. A steady state model is formulated for the updraft fixed bed reactor. Here the predicted optimum gasification efficiency stands at 95.49% with CO, CO2, NO and O2 concentrations as 1301 ppm, 6.5%, 53.7 ppm and 13.5% respectively. The major amendment to the chamber design is proposed on the aspects of air-exit-velocity, i.e. by using smaller diameter of the air nozzles. In doing so, it will create high air-jet penetration in the combustion zone. Higher combustion temperature above 850oC is created for the gasification and combustion zones. This will also reduce NO formation from 54 ppm to 25 ppm at the exit point of the chamber. 2008-10 Thesis http://eprints.utm.my/id/eprint/12196/ http://eprints.utm.my/id/eprint/12196/1/ErnieMatTokitMFKM2008.pdf application/pdf en public masters Universiti Teknologi Malaysia, Faculty of Mechanical Engineering Faculty of Mechanical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TJ Mechanical engineering and machinery
spellingShingle	TJ Mechanical engineering and machinery Mat Tokit, Ernie Design optimization of a fixed bed biomass gasifier of a two stage incinerator
description	Waste wood, a renewable energy source is used as feedstock for Universiti Teknologi Malaysia’s newly-developed two-stage incinerator system. The research goals are to optimize the operation of the thermal system, to improve its combustion efficiency and to minimize its pollutants formation. The work focuses on one of its components, i.e. the primary chamber which comprises of a large updraft fixed-bed chamber, measuring 187.5cm in height and 194.5 cm in diameter respectively. During experimental work, the primary chamber is fed in batches of the processed feedstock while the air for combustion is metered through an eight air nozzle supply system, incorporated at the lower side of the tapered chamber. The feedstock will undergo four different processes; drying, devolatilisation, gasification and combustion. The combustion process is evaluated with the variation of fuel’s moisture content, i.e. set at 17%, 31%, and 40% respectively. The initial experimental work indicates that the temperature and oxide of nitrogen (NO) concentration are decreased with the increase of the moisture in the fuel. Furthermore, the concentration of carbon monoxide (CO) increases with the variation of this operating parameter. However the change for carbon dioxide (CO2) and oxygen (O2) concentrations are only around 1% with the variation of this operating parameter. For optimum operating condition, where the gasification efficiency is 95.53%, the moisture content of the fuel is best set at 17%; giving outlet operating temperature of 550oC and exhaust gas concentrations with 1213 ppm of CO, 6% of CO2, 66 ppm of NO and 14% of O2 respectively. In parallel to the experimental work, a computational fluid dynamics software is used to simulate the performance of the primary chamber at optimum operating condition. This technique provides detail insights on the dynamics of flow and the combustion behavior that occur in the reference chamber. A steady state model is formulated for the updraft fixed bed reactor. Here the predicted optimum gasification efficiency stands at 95.49% with CO, CO2, NO and O2 concentrations as 1301 ppm, 6.5%, 53.7 ppm and 13.5% respectively. The major amendment to the chamber design is proposed on the aspects of air-exit-velocity, i.e. by using smaller diameter of the air nozzles. In doing so, it will create high air-jet penetration in the combustion zone. Higher combustion temperature above 850oC is created for the gasification and combustion zones. This will also reduce NO formation from 54 ppm to 25 ppm at the exit point of the chamber.
format	Thesis
qualification_level	Master's degree
author	Mat Tokit, Ernie
author_facet	Mat Tokit, Ernie
author_sort	Mat Tokit, Ernie
title	Design optimization of a fixed bed biomass gasifier of a two stage incinerator
title_short	Design optimization of a fixed bed biomass gasifier of a two stage incinerator
title_full	Design optimization of a fixed bed biomass gasifier of a two stage incinerator
title_fullStr	Design optimization of a fixed bed biomass gasifier of a two stage incinerator
title_full_unstemmed	Design optimization of a fixed bed biomass gasifier of a two stage incinerator
title_sort	design optimization of a fixed bed biomass gasifier of a two stage incinerator
granting_institution	Universiti Teknologi Malaysia, Faculty of Mechanical Engineering
granting_department	Faculty of Mechanical Engineering
publishDate	2008
url	http://eprints.utm.my/id/eprint/12196/1/ErnieMatTokitMFKM2008.pdf
_version_	1747814905431457792

Design optimization of a fixed bed biomass gasifier of a two stage incinerator

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