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Jianwei Cheng - One of the best experts on this subject based on the ideXlab platform.
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Safety Operations and Assessment for Sealed Mine Atmosphere
Explosions in Underground Coal Mines, 2018Co-Authors: Jianwei ChengAbstract:A new concept, Explosibility safety factor (SF), is introduced and defined to improve the safety for the rescue works. It can clearly show how dangerous the current atmospheric status is if the state point locates in any not-explosive zones and also provides a measurement method to measure the safety margin when dealing with the Explosibility of a sealed mine atmosphere. A series of theoretical explosion risk assessment models to fully analyze the evolution of explosion risk in an underground mine atmosphere are proposed: (1) for an “not-explosive” atmosphere, judging the evolution of explosion risk and estimating the change-of-state time span from “not-explosive” to “explosive”; (2) for an “explosive” atmosphere, a set of mathematical equations are theoretically derived to estimate the inertisation time of a sealed mine atmosphere by using different inerting approaches and the “critical” time span of moving out of explosive zone and stating the best risk mitigation strategy are estimated.
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Application and Illustrative Examples
Explosions in Underground Coal Mines, 2018Co-Authors: Jianwei ChengAbstract:This chapter deals with coding the software program with the Visual Basic language. The computer program named “CCMER” (C omprehensive C onsultation M odel for E xplosion R isk in Mine Atmosphere) which is capable of all the analysing models mentioned in the previous chapters to provide a tool of predicting the gas species change trends and tracking of the Explosibility of mine atmosphere at any time points has been developed. Case studies are also given to illustrate the applications of “CCMER”, the developed computer program.
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Improved Explosibility Diagram Method
Explosions in Underground Coal Mines, 2018Co-Authors: Jianwei ChengAbstract:In this chapter, some of the unique influential factors existing in a mine sealed volume which may greatly change the determination judgments are reviewed and presented. In order to achieve better and more accurate Explosibility judgments, a modified Coward Explosibility diagram method is proposed in this chapter. The important characteristic points or parameters to construct the Explosibility triangle such as: upper flammable limit, lower flammable limit, nose limit, etc. are corrected or modified. The cross-verification study using the USBM Explosibility diagram served as a double check and has also been referenced at the end of this chapter.
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explosion risk assessment model for underground mine atmosphere
Journal of Fire Sciences, 2017Co-Authors: Xixi Zhang, Jianwei Cheng, Apurna GhoshAbstract:In the coal mining industry, explosions or mine fires present the most hazardous safety threats for coal miners or mine rescue members. Hence, the determination of the mine atmosphere Explosibility and its evolution are critical for the success of mine rescues or controlling the severity of a mine accident. However, although there are numbers of methods which can be used to identify the Explosibility, none of them could well indicate the change to the explosion risk time evolution. The reason is that the underground sealed atmospheric compositions are so complicated and their dynamical changes are also affected by various influence factors. There is no one method that could well handle all such considerations. Therefore, accurately knowing the mine atmospheric status is still a complicated problem for mining engineers. Method of analyzing the explosion safety margin for an underground sealed atmosphere is urgently desired. This article is going to propose a series of theoretical explosion risk assessment ...
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Explosibility safety factor an approach to assess mine gas explosion risk
Fire Technology, 2015Co-Authors: Jianwei Cheng, Fu Bao ZhouAbstract:The determination of Explosibility is critical for mine rescues or controlling the severity of a mine accident, especially for the gas explosion event. After a severe coal mine fire or an explosion event, a common practice for minimizing the risk is to seal the related area, and then to inject the inert gas (N2 and/or CO2) into the sealed area to extinguish the fire and prevent potential explosions. At the same time, rescue works will be immediately planned. In order to avoid the risk associated with a potential secondary explosion, the rescue workers are not allowed to go underground until the atmosphere of the sealed area no longer has the possible Explosibility. Therefore, mining engineers must precisely know how dangerous the current situation is and what is the risk degree. One Explosibility method, the Coward Explosibility diagram, can clearly identify the explosive status of a mine atmosphere and track its Explosibility trend as the compositions of mine atmosphere change. However, the Coward diagram can only identify the mine gas Explosibility, but it lacks the ability showing the safety margin. In this paper, a new concept, Explosibility safety factor (SF), is introduced and defined to improve the safety for the rescue works when using the Coward method. It can clearly show how dangerous the current atmospheric status is if the state point locates in any not-explosive zones and also provide a measurement method to scale the safety margin when dealing with the Explosibility of a sealed mine atmosphere. Application of this factor is also demonstrated at the end of the paper.
Paul Amyotte - One of the best experts on this subject based on the ideXlab platform.
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Niacin, lycopodium and polyethylene powder Explosibility in 20-L and 1-m3 test chambers
Journal of Loss Prevention in the Process Industries, 2019Co-Authors: Albert Addo, Faisal Khan, Ashok G. Dastidar, Jérôme Taveau, Luke S. Morrison, Paul AmyotteAbstract:Abstract An experimental program has been undertaken to investigate the Explosibility of selected organic dusts. The work is part of a larger research project aimed at examination of a category of combustible dusts known as marginally explosible. These are materials that appear to explode in laboratory-scale test chambers, but which may not produce appreciable overpressures and rates of pressure rise in intermediate-scale chambers. Recent work by other researchers has also demonstrated that for some materials, the reverse occurs – i.e., values of explosion parameters are higher in a 1-m3 chamber than one with a volume of 20 L. Uncertainties can therefore arise in the design of dust explosion risk reduction measures. The following materials were tested in the current work: niacin, lycopodium and polyethylene, all of which are well-known to be combustible and which cover a relatively wide range of explosion consequence severity. The concept of marginal Explosibility was incorporated by testing both fine and coarse fractions of polyethylene. Experiments were conducted at Dalhousie University using the following equipment: (i) Siwek 20-L explosion chamber for determination of maximum explosion pressure (Pmax), volume-normalized maximum rate of pressure rise (KSt), and minimum explosible concentration (MEC), (ii) MIKE 3 apparatus for determination of minimum ignition energy (MIE), and (iii) BAM oven for determination of minimum ignition temperature (MIT). Testing was also conducted at Fauske & Associates, LLC using a 1-m3 explosion chamber for determination of Pmax, KSt and MEC. All equipment were calibrated against reference dusts, and relevant ASTM methodologies were followed in all tests. The explosion data followed known trends in accordance with relevant physical and chemical phenomena. For example, Pmax and KSt values for the fine sample of polyethylene were higher than those for the coarse sample because of the decrease in particle size. MEC values for all samples were comparable in both the 20-L and 1-m3 chambers. Pmax and KSt values compared favorably in the different size vessels except for the coarse polyethylene sample. In this case, KSt determined in a volume of 1 m3 was significantly higher than the value from 20-L testing. The fact that the 20-L KSt was low (23 bar m/s) does not indicate marginal Explosibility of the coarse polyethylene. This sample is clearly explosible as evidenced by the measured values of MEC, MIE, MIT, and 1-m3 KSt (at both 550 and 600 ms ignition delay times).
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Influence of liquid and vapourized solvents on Explosibility of pharmaceutical excipient dusts
Process Safety Progress, 2014Co-Authors: Nur Hossain, Paul Amyotte, Faisal Khan, Ashok G. Dastidar, Rolf K. Eckhoff, Meftah Abuswer, Yuan ChunmiaoAbstract:Hybrid mixtures of a combustible dust and flammable gas are found in many industrial processes. Such fuel systems are often encountered in the pharmaceutical industry when excipient (nonpharmaceutically active ingredient) powders undergo transfer in either a dry or solvent prewetted state into an environment possibly containing a flammable gas. The research described in this article simulated the conditions of the above scenarios with microcrystalline cellulose and lactose as excipients, and methanol, ethanol, and isopropanol as solvents. Standardized dust Explosibility test equipment (Siwek 20-L explosion chamber, MIKE 3 apparatus, and BAM oven) and ASTM test protocols were used to determine the following Explosibility parameters: maximum explosion pressure (Pmax), volume-normalized maximum rate of pressure rise (KSt), minimum explosible concentration (MEC), minimum ignition energy (MIE), and minimum ignition temperature (MIT). The experimental results demonstrate the significant enhancements in explosion likelihood and explosion severity brought about by solvent admixture in either mode. The extent of solvent influence was found to be specific to the given excipient and method of solvent addition. Solvent burning velocity considerations help to account for some of the experimental observations but for others, a more rigorous evaluation of solvent and excipient physical property data is needed. © 2014 American Institute of Chemical Engineers Process Saf Prog 33: 374–379, 2014
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Myth No. 7 (Ignition Source): Dusts Ignite Only with a High-Energy Ignition Source
An Introduction to Dust Explosions, 2013Co-Authors: Paul AmyotteAbstract:Chapter 8 deals with the myth that dusts ignite only with a high-energy ignition source. The reality is that while energetic ignition sources on the order of several thousand joules are routinely used in closed-vessel dust Explosibility testing to overcome ignitability limitations imposed by the harsh test conditions, there is clear evidence that some dusts will ignite at spark energies less than 1 mJ (millijoule) under conditions of lower turbulence intensity.
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Explosibility of micron- and nano-size titanium powders
Journal of Loss Prevention in the Process Industries, 2013Co-Authors: Simon P. Boilard, Paul Amyotte, Faisal Khan, Ashok G. Dastidar, Rolf K. EckhoffAbstract:Abstract Explosibility of micron- and nano-titanium was determined and compared according to explosion severity and likelihood using standard dust explosion equipment. ASTM methods were followed using a Siwek 20-L explosion chamber, MIKE 3 apparatus and BAM oven. The Explosibility parameters investigated for both size ranges of titanium include explosion severity (maximum explosion pressure (Pmax) and size-normalized maximum rate of pressure rise (KSt)) and explosion likelihood (minimum explosible concentration (MEC), minimum ignition energy (MIE) and minimum ignition temperature (MIT)). Titanium particle sizes were −100 mesh (
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Explosibility of Polyamide and Polyester Fibers
Journal of Loss Prevention in the Process Industries, 2013Co-Authors: Ivan Iarossi, Paul Amyotte, Faisal Khan, Ashok G. Dastidar, Luca Marmo, Rolf K. EckhoffAbstract:The current research is aimed at investigating the explosion behavior of hazardous materials in relation to aspects of particulate size. The materials of study are flocculent (fibrous) polyamide 6.6 (nylon) and polyester (polyethylene terephthalate). These materials may be termed nontraditional dusts due to their cylindrical shape which necessitates consideration of both particle diameter and length. The experimental work undertaken is divided into two main parts. The first deals with the determination of deflagration parameters for polyamide 6.6 (dtex 3.3) for different lengths: 0.3 mm, 0.5 mm, 0.75 mm, 0.9 mm and 1 mm; the second involves a study of the deflagration behavior of polyester and polyamide 6.6 samples, each having a length of 0.5 mm and two different values of dtex, namely 1.7 and 3.3. (Dtex or decitex is a unit of measure for the linear density of fibers. It is equivalent to the mass in grams per 10,000 m of a single filament, and can be converted to a particle diameter.) The Explosibility parameters investigated for both flocculent materials include maximum explosion pressure (Pmax), size-normalized maximum rate of pressure rise (KSt), minimum explosible concentration (MEC), minimum ignition energy (MIE) and minimum ignition temperature (MIT). ASTM protocols were followed using standard dust Explosibility test equipment (Siwek 20-L explosion chamber, MIKE 3 apparatus and BAM oven). Both qualitative and quantitative analyses were undertaken as indicated by the following examples. Qualitative observation of the post-explosion residue for polyamide 6.6 indicated a complex interwoven structure, whereas the polyester residue showed a shiny, melt-type appearance. Quantitatively, the highest values of Pmax and KSt were obtained at the shortest length and finest dtex for a given material. For a given length, polyester displayed a greater difference in Pmax and KSt at different values of dtex than polyamide 6.6. Long ignition delay times were observed in the BAM oven (MIT measurements) for polyester, and video framing of explosions in the MIKE 3 apparatus (MIE measurements) enabled observation of secondary ignitions caused by flame propagation after the initial ignition occurring at the spark electrodes.
Jacob Miller - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the 20 L dust Explosibility testing chamber and comparison to a modified 38 L vessel for underground coal
Elsevier, 2018Co-Authors: Robert Eades, Kyle Perry, Catherine Johnson, Jacob MillerAbstract:The phenomenon of combustible dust explosions is present within many industries. Tests for Explosibility of dust clouds per ASTM E1226 use a 20 L explosive chamber that places the combustible dust directly below the dispersion nozzle which generates a thorough mixture for testing purposes. However, in the underground coal mining industry, there are a number of geologic, mining, and regulatory factors that change the deposition scheme of combustible coal dust. This causes the atmosphere of a coal mine to have a variable rock dust-coal dust mixture at the time of ignition. To investigate the impact of this variable atmosphere, a series of lean Explosibility tests were conducted on a sample of Pittsburgh Pulverized coal dust. These Explosibility tests were conducted in a 38 L chamber with a 5 kJ Sobbe igniter. The 38 L chamber generates a variable air-dust mixture prior to ignition. The test results indicate that the 38 L chamber experiences reduced explosive pressures, and lower Explosibility index values when compared to the 20 L chamber. Keywords: Dust explosion, Coal mining, Coal dust, Explosibility testin
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Evaluation of the 20 L dust Explosibility testing chamber and comparison to a modified 38 L vessel for underground coal
International Journal of Mining Science and Technology, 2018Co-Authors: Robert Quentin Eades, Kyle A. Perry, Catherine E. Johnson, Jacob MillerAbstract:Abstract The phenomenon of combustible dust explosions is present within many industries. Tests for Explosibility of dust clouds per ASTM E1226 use a 20 L explosive chamber that places the combustible dust directly below the dispersion nozzle which generates a thorough mixture for testing purposes. However, in the underground coal mining industry, there are a number of geologic, mining, and regulatory factors that change the deposition scheme of combustible coal dust. This causes the atmosphere of a coal mine to have a variable rock dust-coal dust mixture at the time of ignition. To investigate the impact of this variable atmosphere, a series of lean Explosibility tests were conducted on a sample of Pittsburgh Pulverized coal dust. These Explosibility tests were conducted in a 38 L chamber with a 5 kJ Sobbe igniter. The 38 L chamber generates a variable air-dust mixture prior to ignition. The test results indicate that the 38 L chamber experiences reduced explosive pressures, and lower Explosibility index values when compared to the 20 L chamber.
Yi Luo - One of the best experts on this subject based on the ideXlab platform.
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MODELING ATMOSPHERE COMPOSITION AND DETERMINING Explosibility IN A SEALED COAL MINE VOLUME
Archives of Mining Sciences, 2014Co-Authors: Jianwei Cheng, Yi LuoAbstract:Explosions originated from or around the sealed areas in underground coal mines present a serious safety threat. The Explosibility of the mine atmosphere depends on the composition of oxygen, combustible and inert gases. In additional, the composition in the inaccessible sealed areas change with time under various factors, such as gases emissions, air leakage, inert gases injected, etc. In order to improve mine safety, in this paper, a mathematical model based on the control volume approach to simulate the atmosphere compositions is developed, and the expanded Coward Explosibility triangle diagram is used to assess the mine gas explosion risk. A computer program is developed to carry out the required computations and to display the results. In addition, the USBM Explosibility diagram is also included in the program to serve as a double check.
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MODELING ATMOSPHERE COMPOSITION AND DETERMINING Explosibility IN A SEALED COAL MINE VOLUME MODELOWANIE SKŁADU POWIETRZA I OKREŚLANIE NIEBEZPIECZEŃSTWA WYBUCHU W ZAMKNIĘTEJ PRZESTRZENI W OBRĘBIE KOPALNI WĘGLA
2014Co-Authors: Jianwei Cheng, Yi LuoAbstract:Explosions originated from or around the sealed areas in underground coal mines present a serious safety threat. The Explosibility of the mine atmosphere depends on the composition of oxygen, combustible and inert gases. In additional, the composition in the inaccessible sealed areas change with time under various factors, such as gases emissions, air leakage, inert gases injected, etc. In order to improve mine safety, in this paper, a mathematical model based on the control volume approach to simulate the atmosphere compositions is developed, and the expanded Coward Explosibility triangle diagram is used to assess the mine gas explosion risk. A computer program is developed to carry out the required computations and to display the results. In addition, the USBM Explosibility diagram is also included in the program to serve as a double check.
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Modified explosive diagram for determining gas-mixture Explosibility
Journal of Loss Prevention in the Process Industries, 2013Co-Authors: Jianwei Cheng, Yi LuoAbstract:Abstract Determination of mine gas Explosibility is definitely a significant work for mine safety especially when any mine rescue strategies are under planning or implementing. In detail, its importance can be well understood by the following two aspects: First, if a coal mine's production is under the normal conditions, the underground mine atmosphere must be monitored as a timely matter and its Explosibility should also be determined shortly due to the continuous emission of methane or other combustible gases. Thus, the critical time which means a time period that combustible gases could build up to reach the lower flammable limit and then pass the upper flammable limit can be effectively watched and controlled. Second, when facing a mine rescue work or mitigating a hazard of mine accidents (gas explosion, coal fire, etc.), the Explosibility determination is also very critical for miners' lives. In this paper, a widely used mine gas Explosibility determination method, the Coward diagram, is going to be modified to improve its accuracy. The improvements made in this research effort include: (1) expanding the original Coward diagram; (2) correcting flammable limits; (3) redefining the nose limit for each combustible gas; (4) developing an equation to predict the excess amount of inert gas for individual combustible gas. Finally, the flowchart of the modified Coward Explosibility diagram method is listed. By a cross-verification study, it shows that the modified Coward method has better accuracy and reliability and could be applied in practices.
Robert Quentin Eades - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the 20 L dust Explosibility testing chamber and comparison to a modified 38 L vessel for underground coal
International Journal of Mining Science and Technology, 2018Co-Authors: Robert Quentin Eades, Kyle A. Perry, Catherine E. Johnson, Jacob MillerAbstract:Abstract The phenomenon of combustible dust explosions is present within many industries. Tests for Explosibility of dust clouds per ASTM E1226 use a 20 L explosive chamber that places the combustible dust directly below the dispersion nozzle which generates a thorough mixture for testing purposes. However, in the underground coal mining industry, there are a number of geologic, mining, and regulatory factors that change the deposition scheme of combustible coal dust. This causes the atmosphere of a coal mine to have a variable rock dust-coal dust mixture at the time of ignition. To investigate the impact of this variable atmosphere, a series of lean Explosibility tests were conducted on a sample of Pittsburgh Pulverized coal dust. These Explosibility tests were conducted in a 38 L chamber with a 5 kJ Sobbe igniter. The 38 L chamber generates a variable air-dust mixture prior to ignition. The test results indicate that the 38 L chamber experiences reduced explosive pressures, and lower Explosibility index values when compared to the 20 L chamber.
