Numerical investigation on flame propagation and pressure development in vented explosion

The understanding of the explosion phenomenon is essential for an effective and safe engineering practice, particularly in refinery and chemical plants. Explosion venting technology is one of the effective techniques in protection measures against accidental internal gas explosions by relieving the...

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Main Author:	Mohd. Zaidi, Nur Hazwani Fatihah
Format:	Thesis
Language:	English
Published:	2017
Subjects:	TP Chemical technology
Online Access:	http://eprints.utm.my/id/eprint/78372/1/NurHazwaniFatihahMFChE2017.pdf
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spelling	my-utm-ep.783722018-08-26T04:56:09Z Numerical investigation on flame propagation and pressure development in vented explosion 2017-08 Mohd. Zaidi, Nur Hazwani Fatihah TP Chemical technology The understanding of the explosion phenomenon is essential for an effective and safe engineering practice, particularly in refinery and chemical plants. Explosion venting technology is one of the effective techniques in protection measures against accidental internal gas explosions by relieving the pressure generated within the volume. The factors governing to the explosion development such as geometry, ignition position and vent burst pressure have been extensively studied. However, the details physical and dynamic mechanism responsible for the generation of significant pressure peaks during vented explosions is insufficient, making it difficult for designing the accurate explosion reliefs in practical situations. The primary motivation of this research was to better understand the turbulent flame propagation in vented gas explosion using modelling approach. Computational Fluid Dynamic (CFD) analyses using ANSYS Fluent is adopted to study the vented gas explosions process. Computations of the deflagrating flames were run in small-scale combustion chambers with two different volume sizes of 0.02 m3 and 0.0065 m3, closed at the one end and open at the opposite face. Only stoichiometric concentration of hydrogen, propane and methane-air mixtures were considered with different ignition positions (end and central ignition) and vent static burst pressure (Pv). The condition of the analysis was following experimental data done from previous researcher. From the findings, end ignition gave higher reduced overpressure on simulation results, about 1.4 times higher compared to central ignition due to the larger flame surface area attained. Thus, the time flame needed to reach the venting area became longer. The vents inclusion in the enclosures caused the reduction on the peak overpressure. As the Pv was further increased, i.e. from 98 mbar to 424 mbar, the venting effectiveness became lesser by 24 % for the methane explosion but not to the vented propane explosion in simulation analysis. This work confirmed that fuel reactivity gave important role on determining the venting effectiveness as stoichiometric hydrogen attained higher reduced explosion pressure (Pred) of 4.150 bar compared that of stoichiometric methane and propane vented explosion, 0.945 and 1.045 bar, respectively, if ignited at central location. It can be said that the distance from the location of ignition to the vent area, the fuel reactivity and Pv have significant roles to determine the duration of the pressure build up and the amount of vented mass, which describes the external explosion intensity. 2017-08 Thesis http://eprints.utm.my/id/eprint/78372/ http://eprints.utm.my/id/eprint/78372/1/NurHazwaniFatihahMFChE2017.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:105164 masters Universiti Teknologi Malaysia, Faculty of Chemical Engineering Faculty of Chemical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TP Chemical technology
spellingShingle	TP Chemical technology Mohd. Zaidi, Nur Hazwani Fatihah Numerical investigation on flame propagation and pressure development in vented explosion
description	The understanding of the explosion phenomenon is essential for an effective and safe engineering practice, particularly in refinery and chemical plants. Explosion venting technology is one of the effective techniques in protection measures against accidental internal gas explosions by relieving the pressure generated within the volume. The factors governing to the explosion development such as geometry, ignition position and vent burst pressure have been extensively studied. However, the details physical and dynamic mechanism responsible for the generation of significant pressure peaks during vented explosions is insufficient, making it difficult for designing the accurate explosion reliefs in practical situations. The primary motivation of this research was to better understand the turbulent flame propagation in vented gas explosion using modelling approach. Computational Fluid Dynamic (CFD) analyses using ANSYS Fluent is adopted to study the vented gas explosions process. Computations of the deflagrating flames were run in small-scale combustion chambers with two different volume sizes of 0.02 m3 and 0.0065 m3, closed at the one end and open at the opposite face. Only stoichiometric concentration of hydrogen, propane and methane-air mixtures were considered with different ignition positions (end and central ignition) and vent static burst pressure (Pv). The condition of the analysis was following experimental data done from previous researcher. From the findings, end ignition gave higher reduced overpressure on simulation results, about 1.4 times higher compared to central ignition due to the larger flame surface area attained. Thus, the time flame needed to reach the venting area became longer. The vents inclusion in the enclosures caused the reduction on the peak overpressure. As the Pv was further increased, i.e. from 98 mbar to 424 mbar, the venting effectiveness became lesser by 24 % for the methane explosion but not to the vented propane explosion in simulation analysis. This work confirmed that fuel reactivity gave important role on determining the venting effectiveness as stoichiometric hydrogen attained higher reduced explosion pressure (Pred) of 4.150 bar compared that of stoichiometric methane and propane vented explosion, 0.945 and 1.045 bar, respectively, if ignited at central location. It can be said that the distance from the location of ignition to the vent area, the fuel reactivity and Pv have significant roles to determine the duration of the pressure build up and the amount of vented mass, which describes the external explosion intensity.
format	Thesis
qualification_level	Master's degree
author	Mohd. Zaidi, Nur Hazwani Fatihah
author_facet	Mohd. Zaidi, Nur Hazwani Fatihah
author_sort	Mohd. Zaidi, Nur Hazwani Fatihah
title	Numerical investigation on flame propagation and pressure development in vented explosion
title_short	Numerical investigation on flame propagation and pressure development in vented explosion
title_full	Numerical investigation on flame propagation and pressure development in vented explosion
title_fullStr	Numerical investigation on flame propagation and pressure development in vented explosion
title_full_unstemmed	Numerical investigation on flame propagation and pressure development in vented explosion
title_sort	numerical investigation on flame propagation and pressure development in vented explosion
granting_institution	Universiti Teknologi Malaysia, Faculty of Chemical Engineering
granting_department	Faculty of Chemical Engineering
publishDate	2017
url	http://eprints.utm.my/id/eprint/78372/1/NurHazwaniFatihahMFChE2017.pdf
_version_	1747817973148549120

Numerical investigation on flame propagation and pressure development in vented explosion

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