12 Journal Articles Investigating Explosion of Hybrid Mixtures
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12 Journal Articles Investigating Explosion of Hybrid Mixtures
Hybrid Mixture Explosion
Hybrid mixtures contain both a combustible dust and flammable gas. Explosion of hybrid mixtures represent an enhanced industry hazard as both the severity and likelihood can increase from the presence of the second fuel.
This post briefly summarizes 12 journal articles in this research area. Relevant industries, main findings, and points of disagreement are discussed. The final two sections give links to three minute summaries of each article and the full reference information.
The main focus of this post is hybrid explosion parameters determined in closed chambers at laboratory scale. For the current purposes, explosion severity is indicated by maximum rate of pressure rise and likelihood is indicated by explosibility limits. It is important to note that other parameters such as maximum overpressure, minimum ignition energy, and minimum ignition temperature may also be important to consider.
Other posts relevant to hybrid explosion can be found under the Hybrid Explosion and Hybrid Flame Structure keywords. A full listing of posts in other areas relevant to dust and gas explosion can be found from the Blog Keywords or Blog Categories pages.
Industry Coverage
The industries covered in this summary include mining, nuclear, pharmaceutical, and general processing. Explosion of hybrid mixtures in the mining industry is explored by Li et al., 2012 [1] and Ajrash et al., 2016 [2]. Both authors focus on adding small amounts of methane gas to explosible coal dust concentrations.
Hybrid mixtures in the nuclear industry are explored by Denkevits, 2007 [3], Denkevits, 2010 [4], Khalil, 2013 [5], and Denkevits and Hoess, 2015 [6]. These authors investigate explosion of hydrogen gas with the addition of graphite/carbon, tungsten, and aluminum dusts.
A variety of hybrid mixtures relevant to the pharmaceutical industry are explore by Dufaud et al., 2008 [7], Dufaud et al., 2009 [8], Garcia-Agreda et al., 2011 [9], Sanchirico et al., 2011 [10], and Hossain, 2014 [11]. These studies cover the largest breadth of explosion characteristics including severity, explosibility limits, and characterizing the explosion process for hybrid mixtures.
The last paper included in this review is from Pilao et al., 2006 [12]. This paper investigates the explosibility of cork dust and methane gas mixtures, and is relevant to the manufacturing of cork stoppers. This work demonstrates the importance of hybrid mixtures in general processing industries.
Summary of Main Findings
The largest finding across all papers is that even small amounts of the second fuel can greatly change the explosion severity and likelihood of the first. In most cases explosion severity is enhanced significantly, especially at fuel lean concentrations (e.g., see [1, 4, 11]). Adding a combustible dust to a fuel rich flammable gas, may cause a reduction in explosion severity [3]; However, it is important to keep in mind that dust may also increase the local turbulence leading to increased explosion severity instead (e.g., see Amyotte et al., 1988 [13]).
Almost all papers that investigate explosibility limits report explosions for mixtures below the gas lower flammability limit (LFL) and dust minimum explosible concentration (MEC) [2, 5, 8, 9, 10, 12]. This is important for explosion prevention as the presence of hybrid conditions mean that explosions can occur more easily than if only a single fuel is anticipated. The work of Dastidar et al., 2005 [14] presents considerations for hazard analysis of these mixtures in processing plants.
Two competing theories have been proposed for predicting explosion limits of hybrid mixtures: Le Chatelier’s Law and Bartknecht’s relation. See the derivation by Mashuga and Crowl [15] and the textbook by Bartknecht [16] for more information on these two theories, respectively. Further discussion on the experimental findings from the 12 papers summarized here is given in the “Points of Disagreement” Section below.
The work of Garcia-Agreda et al., 2011 [9] attempts to characterize the explosion process for hybrid mixtures. These authors proposed five explosion regimes depending on the amounts of fuel relative to their flammability criteria:
- Dust Driven Explosion – Dust > MEC, Gas < LFL
- Gas Driven Explosion – Dust < MEC, Gas > LFL
- Dual Fuel Explosion – Dust > MEC, Gas > LFL
- Synergistic Explosion – Dust < MEC, Gas < LFL
- No Explosion
This approach is useful for envisioning the combustion phenomena occurring for hybrid mixtures. This work was extended by Sanchirico et al., 2011 [10] to different ignition energy and turbulence levels. The work of Denkevits, 2007 [3], Denkevits, 2010 [4], and Denkevits and Hoess, 2015 [6] also demonstrate the combustion stages for hybrid mixtures and these authors developed the following groupings: gas-only explosion, two-step explosion, single-step explosion, and dust-only explosion.
Points of Disagreement
The first major point of disagreement focuses on the worst-case-scenario for explosion of hybrid mixtures. The results of Garcia-Agreda et al., 2011 [9] and Sanchirico et al., 2011 [10] suggest that the worst-case condition is pure gas near its stoichiometric concentration. These findings are in contrast to several studies [7, 8, 5, 4, 6] which demonstrate “more than additive effects” (term used by Dufaud et al., 2008 [7]). In these studies the worst case explosion occurred at different mixtures of dust and gas. The effect of chemical kinetics and dust-turbulence interaction on hybrid explosion severity is not well understood and the worst-case explosion severity question poses real problems for researchers and industry alike.
The second unresolved point of disagreement involves explosion limits of hybrid mixtures. Two competing theories have been presented in the literature. Le Chatelier’s Law treats the solid/gas mixture as a gas/gas mixture and assumes linear mixing between the explosion limits:
&bg=ffffff&fg=000&s=0 "c = MEC\left(1 - \frac{y}{LFL}\right)")
where the dust concentration at the flammability limit (
) can be estimated from the gas concentration (
). The individual flammability limits MEC and LFL are from the pure fuels alone. As explained by Mashuga and Crowl [15], this theory assumes that the fuels have similar flame temperature and combustion properties.
) can be estimated from the gas concentration (). The individual flammability limits MEC and LFL are from the pure fuels alone. As explained by Mashuga and Crowl [15], this theory assumes that the fuels have similar flame temperature and combustion properties.
The second competing theory is Bartknecht’s quadratic relation which states that explosion limits are wider than predicted using Le Chatelier’s Law. It is generally applied for fuels with low burning velocities (e.g., methane):
%5E%7B2%7D&bg=ffffff&fg=000&s=0 "c = MEC\left(1 - \frac{y}{LFL}\right)^{2}")
. This relation suggests that less dust is required to generate an explosible mixture than predicted using linear mixing at a given gas concentration.
From the 12 articles reviewed significant deviations were found in the conclusions on explosibility limits. Garcia-Agreda et al., 2011 [9] saw agreement between Le Chatelier’s Law and the flammability limits of methane gas and niacin dust mixtures. Dufaud et al., 2009 [8] and Ajrash et al., 2016 [2] found wider explosion limits as predicted using Bartknecht’s relation. However, in contrast to both these theories, several studies (Sanchirico et al., 2011 [10], Pilao et al., 2006 [12], and Khalil et al., 2013 [5]) found explosion limits narrower than predicted using either approach. These conflicting results demonstrate a need to better understand and characterize hybrid explosion limits.
Conclusion
This literature summary demonstrated several important points regarding explosion of hybrid mixtures. Again, it is important to highlight that parameters other than maximum rate of pressure rise and lower explosibility limits may be important to consider depending on the processing application.
The papers summarized in this post give a broad overview of the available literature. This summary is not all-inclusive and several important papers may be absent. For other paper summaries included on this website see the “Three Minute Papers” category or the Blog Keywords page.
Other papers that are of particular interest to explosion limits of hybrid mixtures include Amyotte et al., 1993 [17], Chatrathi, 1994 [18], Landman, 1995 [19], Nifuku et al., 2006 [20], Prugh, 2008 [21], Jiang et al., 2014 [22], Jiang et al., 2015 [23], and Addai et al., 2015 [24]. These papers should be reviewed by anyone looking to understand this research area.
Lastly, if you have any comments or questions please post them below. No thought is too small and I would love to hear from you! If you would like to connect further or discuss off-line you can reach me from the Contact Me page or at chris@mydustexplosionresearch.com.
12 Journal Articles for Explosion of Hybrid Mixtures
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| Major Finding: Hybrid flammability limits for cork dust/methane mixtures are narrower than the predictions of Le Chatelier’s Law | Major Finding: At medium gas concentration a two-stage explosion process occurs while at higher gas concentrations a single-stage explosion occurs | Major Finding: Hybrid mixtures can have “more than additive” effects on explosion consequence |
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| Major Finding: Hybrid explosibility limits are wider than predicted by Le Chatelier’s Law | Major Finding: Explosion of hybrid mixtures involving tungsten and hydrogen are more violent then hydrogen alone under fuel lean conditions | Major Finding: Hybrid explosions can be divided into five categories based on the fuel concentration |
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| Major Finding: Explosion severity decreases with dust addition along lines of constant mixed stoichiometric ratio | Major Finding: Explosion likelihood and severity increases with an increase in hydrogen gas content in the coal volatiles | Major Finding: Explosion severity of stoichiometric hydrogen is significantly increased by the presence of activated carbon dust |
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| Major Finding: Explosion severity and likelihood increase with addition of solvent to the dust in liquid or vapour form | Major Finding: At high dust concentrations hydrogen gas only acts to ignite the dust but is not involved in the subsequent combustion process | Major Finding: The explosion limits of coal/methane mixtures lie between Le Chatalier’s Law and Bartknecht’s relation |
Reference List for Explosion of Hybrid Mixtures
- Q. Li, B. Lin, H. Dai, and S. Zhao, “Explosion characteristics of H$_{2}$/CH$_{4}$/air and CH$_{4}$/coal dust/air mixtures,” Powder technology, vol. 229, pp. 222-228, 2012.
[Bibtex] [Summary] [Link]
- M. J. Ajrash, J. Zanganeh, and B. Moghtaderi, “Effects of ignition energy on fire and explosion characteristics of dilute hybrid fuel in ventilation air methane,” Journal of loss prevention in the process industries, vol. 40, pp. 207-216, 2016.
[Bibtex] [Summary] [Link]
- A. Denkevits, “Explosibility of hydrogen–graphite dust hybrid mixtures,” Journal of loss prevention in the process industries, vol. 20, pp. 698-707, 2007.
[Bibtex] [Summary] [Link]
- A. Denkevits, “Hydrogen/dust explosion hazard in ITER: Effect of nitrogen dilution on explosion behavior of hydrogen/tungsten dust/air mixtures,” Fusion engineering and design, vol. 85, pp. 1059-1063, 2010.
[Bibtex] [Summary] [Link]
- Y. Khalil, “Experimental investigation of the complex deflagration phenomena of hybrid mixtures of activated carbon dust/hydrogen/air,” Journal of loss prevention in the process industries, vol. 26, pp. 1027-1038, 2013.
[Bibtex] [Summary] [Link]
- A. Denkevits and B. Hoess, “Hybrid H$_{2}$/Al dust explosions in Siwek sphere,” Journal of loss prevention in the process industries, vol. 36, pp. 509-521, 2015.
[Bibtex] [Summary] [Link]
- O. Dufaud, L. Perrin, and M. Traoré, “Dust/vapour explosions: Hybrid behaviours?,” Journal of loss prevention in the process industries, vol. 21, pp. 481-484, 2008.
[Bibtex] [Summary] [Link]
- O. Dufaud, L. Perrin, S. Traoré, S. Chazelet, and D. Thomas, “Explosion of vapour/dust hybrid mixtures: A particular class,” Powder technology, vol. 190, pp. 269-273, 2009.
[Bibtex] [Summary] [Link]
- A. Garcia-Agreda, A. Di Benedetto, P. Russo, E. Salzano, and R. Sanchirico, “Dust/gas mixtures explosion regimes,” Powder technology, vol. 205, pp. 81-86, 2011.
[Bibtex] [Summary] [Link]
- R. Sanchirico, A. Di Benedetto, A. Garcia-Agreda, and P. Russo, “Study of the severity of hybrid mixture explosions and comparison to pure dust-air and vapour-air explosions,” Journal of loss prevention in the process industries, vol. 24, pp. 648-655, 2011.
[Bibtex] [Summary] [Link]
- N. Hossain, P. Amyotte, M. Abuswer, A. Dastidar, F. Khan, R. Eckhoff, and Y. Chunmiao, “Influence of liquid and vapourized solvents on explosibility of pharmaceutical excipient dusts,” Process safety progress, vol. 33, pp. 374-379, 2014.
[Bibtex] [Summary] [Link]
- R. Pilão, E. Ramalho, and C. Pinho, “Explosibility of cork dust in methane/air mixtures,” Journal of loss prevention in the process industries, vol. 19, pp. 17-23, 2006.
[Bibtex] [Summary] [Link]
- P. R. Amyotte, S. Chippett, and M. J. Pegg, “Effects of turbulence on dust explosions,” Progress in energy and combustion science, vol. 14, p. 293–-310, 1988.
[Bibtex] [Summary] [Link]
- A. G. Dastidar, B. Nalda-Reyes, and J. C. Dahn, “Evalutation of dust and hybrid mixture explosion potential in process plants,” Process safety progress, vol. 24, pp. 294-298, 2005.
[Bibtex] [Summary] [Link]
- C. V. Mashuga and D. A. Crowl, “Derivation of Le Chatelier’s mixing rule for flammable limits,” Process saftey progress, vol. 19, pp. 112-117, 2000.
[Bibtex]
- W. Bartknecht, Dust explosions: course, prevention, protection, Springer-Verlag Berlin and Heidelberg GmbH & Co. K, 1989.
[Bibtex] [Link]
- P. R. Amyotte, K. J. Mintz, M. J. Pegg, and Y. H. Sun, “The ignitability of coal dust-air and methane-coal dust-air mixtures,” Fuel, vol. 72, pp. 671-679, 1993.
[Bibtex]
- K. Chatrathi, “Dust and hybrid explosibility in a 1 m$^{3}$ spherical chamber,” Process saftey progress, vol. 13, pp. 183-189, 1994.
[Bibtex] [Summary] [Link]
- G. V. R. Landman, “Ignition behavior of hybrid mixtures of coal dust, methane, and air,” The journal of south african institute of mining and metallurgy, vol. 95, pp. 45-50, 1995.
[Bibtex]
- M. Nifuku, T. H., K. Fujino, K. Takaichi, C. Barre, P. E., M. Hatori, S. Fujiwara, S. Horiguchi, and I. Sochet, “Ignitability assessment of shredder dusts of refrigerator and the prevention of the dust explosion,” Journal of loss prevention in the process industries, vol. 19, pp. 181-186, 2006.
[Bibtex]
- R. W. Prugh, “The relationship between flash point and LFL with application to hybrid mixtures,” Process saftey progress, vol. 27, pp. 156-163, 2008.
[Bibtex]
- J. Jiang, Y. Liu, and S. Mannan, “A correlation of the lower flammability limit for hybrid mixtures,” Journal of loss prevention in the process industries, vol. 32, pp. 120-126, 2014.
[Bibtex]
- J. Jiang, Y. Liu, C. Mashuga, and S. Mannan, “Validation of a new formula for predicting the lower flammability limit of hybrid mixtures,” Journal of loss prevention in the process industries, vol. 35, pp. 52-58, 2015.
[Bibtex]
- E. Addai, D. Gabel, and U. Krause, “Lower explosion limit of hybrid mixtures of burnable gas and dust,” Journal of loss prevention in the process industries, vol. 36, pp. 497-504, 2015.
[Bibtex]
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