Dust Explosion Risk Research Articles

Effect of particle size reduction due to dust dispersion on minimum ignition energy (MIE)

The 20-L dust explosion apparatus is widely used for dust explosion risk assessment, however the 1-m3 apparatus remains the gold standard for explosion testing by generating a turbulent dust cloud consistent with industrial scenarios. Recent studies show a 1-m3 dispersion leads to particle breakage, which can impact risk assessment. However, the effect of particle breakage on explosion risk assessment is not quantified.The focus of this work is to measure particle breakage in a 1-m3 and to quantify the effect of resulting particle size distribution shift on the explosion risk assessment by measuring change in the minimum ignition energy (MIE). We observed Ascorbic Acid particle size reduction in a 1-m3, resulting in a reduced post-dispersion MIE as compared to the pre-dispersion sample. This work aims to create awareness of dust particle breakage to improve the risk assessment process, to better prevent incidents.

Niacin, lycopodium and polyethylene powder explosibility in 20-L and 1-m3 test chambers

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).

Dust explosion hazard in the textile industry

The textile industry is not considered among those at high dust explosion risk, as official statistics (CSB 2010, Abbasi and Abbasi 2007, Yuan et al. 2015) account for a low incidence of episodes. Despite these data, there is also evidence that dust explosions may affect the textile industry with severe consequences. The Harbin linen explosion in China ( Hailin, 1988, Bowen 1988, Eckhoff 2003) is probably recognized as having been the most severe episode. Marmo et al. (2010), Piccinini (2008), Salatino et al. (2012) and the U.S. Fire Administration (1995) have discussed dust explosion episodes involving the textile compartment, with nylon flock and wool dust explosions. Amyotte summarized the state-of-the-art knowledge about flocculent materials (which mainly originate from the textile industry), explosion hazards, and the related studies in chapter thirteen of his well-known book (Amyotte 2013). The textile industry has two particular features regarding the dust explosion risk:a.The dust produced as a by-product of the textile process often belongs to the non-traditional dust category, as a result of the type of materials being handled, which are characterized by a marked flocculent attitude. Amyotte and his co-workers discussed flocculent dust behavior and the related risks in detail (Amyotte et al. 2011, 2012a, 2012b);b.The textile industry often needs control of the ambient moisture, which is generally accomplished using ventilation and environment humidification; the latter naturally implies a reduction in the risk of explosions. These particular features suggest that the risk of dust explosions in the textile industry deserves a dedicated discussion. The number of flocculent dust studies is somewhat limited. The role played by the particle size and aspect ratio (namely the diameter-to-length ratio) in explosibility proneness is still unclear. Worsfold et al. (2012) reported the importance of enlarging the knowledge on the hazards related to unconventional dust since most studies have focused on traditional dust. This work investigates the explosion hazards related to dust generated in the textile industry. Moreover, it presents some experimental results obtained by the authors, and detailed in Marmo et al. (2016, 2018), and illustrates the perspective of the study to increase the safety culture of these particular materials.

A study on the FTIR spectra of pre- and post-explosion coal dust to evaluate the effect of functional groups on dust explosion

Fourier transform infrared (FTIR) spectra of coal dust and its explosion solid residues were studied. Coal dust explosion test was carried out on a 20-L explosion device, and the variation of different functional groups and FTIR structural parameters of pre- and post-explosion dust were semi-quantitatively analyzed by deconvolution of the FTIR spectra. In addition, the relationship of explosion pressure (Pm) and pressure rise rate ((dP/dt)m) with functional groups was investigated. The results show that the largest consumption of functional groups in coal dust explosion process is distributed in 1800–1000cm−1 band, and most of the ether oxygen bond, methyl and benzene ring are removed from the coal macromolecule. The improved condensation degree of coal macromolecular aromatic ring and the decreased aliphatic side chains lead to a more compact coal molecular structure. The consumption of functional groups during coal dust explosion is positively correlated with the Pm and (dP/dt)m. The research provides a new feasible method for the evaluation of the organic dust explosion risk by its functional group. Moreover, it can be used effectively as basis for suppressing the organic dust explosion.

Effect of particle morphology on dust minimum ignition energy

Dust explosions are a threat to process industries. Studies have examined the effect of (particle size, chemical composition, and polydispersity) on dust explosion potential and severity; however the effect of particle morphology on dust explosions has largely been neglected. This work aims to show particle morphology has an important role in influencing dust minimum ignition energy (MIE). Two aluminum dust samples (spherical and irregular) with similar size distribution, polydispersity and chemical composition were examined in the Kühner MIKE3 MIE apparatus. It was found that irregular shaped dust has lower MIE compared to spherical shaped dust. This is attributed to the higher specific surface area of irregular shaped dust, which affects the dust cloud dynamics (turbulence, cloud concentration) and leads to lower resistance to thermal conduction. This study highlights the importance of particle morphology in affecting dust explosion parameters and makes a case to include it in dust explosion risk assessment.

Dust explosion risk in metal workings

Several episodes of metal dust explosions have been reported to have affected industries throughout the world, some of which have caused huge losses (Li et al., 2016). These dusts are typically wastes or by-products derived from machinery within metal manufacturing plants, which are collected in abatement systems (suction units, bag filters). A recent work by Marmo et al. (2017) has demonstrated the deflagration hazards of these dusts and how they are influenced by the particle size (mainly d10), chemical composition and metal oxide content.The dust samples studied in this work were collected from the following mechanical workings of metals.All these unit operations involve the generation of by-products or scraps that may be classified as dust, with different size distributions and chemical compositions, which of course depend on the nature of the processed goods. Among these, it is known that the aluminum industry is affected by a significant hazard, due to the high reactivity of aluminum dust. However, ferrous dust is also reactive and widespread. Light alloys, such as Magnesium alloys, are becoming frequent, especially in the automotive and aerospace industries. Therefore, new hazards are now coming to light.This work presents a study of 43 metal dust samples, collected at various process plants, and discusses how the unit operation that generated the dust samples may influence their ignition sensitivity and explosion violence. The paper includes size distribution and chemical characterization data, and SEM observations of the samples, as well as the results of KST and Pmax measurements.Of all the studied dusts, 59% were found to be explosible, according to the standard test (ISO 80079-20-2), while 100% of the samples collected at some of the dust abatement systems were explosible. Process dusts, such those collected at metal recovery plants from exhaust catalysts or foundry wastes, were found to be less hazardous. The findings of the work could contribute toward identifying the most hazardous operations and suggesting adequate explosion moderation measures for the metal manufacturing industry.

Minimum ignition energy and minimum explosible concentration of L-isoleucine and glycine powder

In this study, Minimum Ignition Energy (MIE) and Minimum Explosible Concentration (MEC) of L-isoleucine and glycine powder with two different particle size distributions were experimentally investigated. The experimental results showed that the values of MIE and MEC of L-isoleucine powder were lower than those of glycine powder. The pyrolysis and the combustible products of glycine and L-isoleucine powders were measured. The results showed that a number of flammable and combustible materials are formed during the pyrolysis of L-isoleucine, although few flammable compounds are generated during the pyrolysis of glycine due to polymerization. This result indicated that the L-isoleucine powder has a high risk of dust explosion as compared to the glycine powder. Consequentially, an appropriate risk assessment for the L-isoleucine powder with fine particles is necessary in the powder handle processes.

Development of dust ignition protected electrically powered forklift truck for combustible dust environment

Industries dealing with explosive gases and combustible dusts in processing or production are always at higher risk of gas or dust explosion. Purified terephthalic acid (PTA) plant of Indian Oil Corporation Ltd. (IOCL), Panipat, India has similar risk of dust explosion hazard, since PTA is a combustible substance in the form of dust or layer. To load, unload and transport the PTA bags in the plant, special forklift trucks are required. A prototype forklift truck for combustible dust atmosphere was developed in collaboration with M/s Action Construction Equipment Ltd. (ACE), Palwal, India. The electrical components with dust ignition protected design have been manufactured by ACE in consultation with CSIR-CIMFR, Dhanbad, India. All other possible sources of ignition are identified and suitable components/parts of forklift are used for hazardous atmosphere. This paper presents the design requirements of a dust ignition protected and battery operated forklift truck for safe use in zone 22 combustible dust atmosphere of the plant. [Received: December 24, 2016; Accepted: December 6, 2017]

Classification of particle breakage due to dust dispersion

Dust explosions are a major challenge in the area of process safety. Incidents occur on a frequent basis causing loss of life and property. Several standards such as ASTM, ISO etc. provide methods and procedures for explosion risk assessment by testing explosion parameters (Pmax and KSt) in the standard 20-L or 1-m3 apparatus. However, it is assumed that particle size distribution of the dispersed dust remains unaltered throughout the testing procedure. Recent studies have found that dust particle size distribution can significantly reduce upon dispersion in the standard 20-L and 36-L apparatus, which can affect the explosion parameters. The reduction in particle size distribution due to the dispersion process depends on the dust and explosion apparatus. Therefore, it is necessary to quantify the particle size reduction of different dusts due to dispersion in various explosion apparatuses (20-L, 36-L and 1-m3) and correlate it to the dust properties (brittleness index (hardness, fracture toughness) that influence particle breakage.This study aims to investigate post-dispersion particle size reduction in the 20-L, 36-L and 1-m3 dust explosion apparatus and classify dusts into particle breakage categories, with a range of brittleness index associated with each category. It will help the process industries identify dusts that are susceptible to breakage based on their brittleness index and prone to give misleading explosion results during dust explosion testing, permitting a proper dust explosion risk assessment. Ascorbic Acid, Acetaminophen (Paracetamol), Anthraquinone, Active Charcoal, Pittsburgh Pulverized Coal (PPC), Cornstarch, Lycopodium clavatum, and Polyethylene were used in this study. These materials were dispersed in the 20-L, 36-L and 1-m3 apparatus at a concentration of 500 g/m3 and post-dispersion samples were analyzed for particle size distribution changes. The mechanical properties (hardness and fracture toughness) of these materials were measured using Nanoindentation. The dispersion-induced change in size distribution was correlated to the measured mechanical properties of the dusts.Dispersion results show the 20-L and 36-L dust explosion apparatus cause significantly more particle breakage than the 1-m3 apparatus. Particle breakage is highest in Ascorbic Acid followed by Acetaminophen, Anthraquinone, Active Charcoal, and Pittsburgh Pulverized Coal, respectively. Cornstarch, Lycopodium clavatum and Polyethylene did not undergo particle size reduction due to dispersion. In addition, the 1-m3 apparatus caused particle breakage only in Ascorbic Acid, Acetaminophen and Anthraquinone. Nanoindentation results show Ascorbic Acid has the highest brittleness index value followed by Acetaminophen, Anthraquinone, Active Charcoal, and Pittsburgh Pulverized Coal, respectively. The brittleness index correlates directly to the particle breakage trend. Based on the results, Ascorbic Acid, Acetaminophen and Anthraquinone were classified into class I breakage category (high breakage). These materials are most susceptible to giving misleading explosion results because of altered particle size distributions. Active Charcoal and Pittsburgh Pulverized Coal were classified into class II breakage category (medium breakage), while Cornstarch, Lycopodium clavatum and Polyethylene were placed into class III breakage category (little or no breakage).

Development of research work in the air-water spraying area for reduction of methane and coal dust explosion hazard as well as for dust control in the Polish mining industry

The article presents a method for equipment designing and techniques to reduce methane ignition hazard, excessive dust in the place of operation and in conveyor transportation lines as well as methods to eliminate the risk of coal dust explosion. It describes technical solutions, the effects of these solutions and tests’ results related to effectiveness of the described air-water solutions as well as water spraying devices. The spraying systems used in longwall shearers and roadheaders, on conveyor belt transfer points as well as the spraying curtains in the roadways are described. A new approach to the assessment of the safety level in the zones protecting against coal dust explosion hazard is also given. Intensity of dust accretion along the explosion protecting zones is analyzed. The spraying device is suggested, the operation of which depends on dust concentration in the ventilation air. The article presents the results of tests on the effectiveness in dust reduction and suppression of methane ignition. The tests were carried out in the laboratory, on testing facilities and in-situ.

Exposure to Harmful Dusts on Fully Powered Longwall Coal Mines in Poland.

The mining production process is exposed to a series of different hazards. One of them is the accumulation of dust which can pose a serious threat to the life and health of mine workers. The analysis of dust hazard in hard coal mining should include two aspects. One is the risk of coal dust explosions, which poses a direct risk of injury or even loss of life, the second is the risk of harmful dust, associated with the possibility of negative health effects as a result of long-term exposure to dust in the worker’s body. The technologies currently applied in underground mining produce large amounts of coal and stone dust. Long-term exposure to dust and crystalline silica may cause chronic respiratory disease. The article presents the results of tests on the dust levels in the area of a fully-powered longwall. The tests were conducted for five longwalls from different hard coal mines. In each of them, the average values of inhalable and respirable dust as well as the percentage content of free silica in the dust were determined in ten selected working positions. Additionally, for the longwall with the highest dust concentration, the levels of dust were determined for the basic activities related to the phases of the technological cycle. The comparative analysis conducted and the results obtained demonstrate large variations in the dust levels in the different areas. The permissible values were significantly exceeded in a number of cases. This poses a great threat to the health of Polish miners. The results obtained indicate that it is necessary to undertake more effective measures in order to improve the working environment of the crew in hard coal mines.

Study of the explosible properties of textile dusts

In the past, the risk of dust explosions in the textile industry was considered very limited or even negligible. This was probably a consequence of the limited number of accidents that affected this industry, according to the available statistics (Abbasi and Abbasi, 2007; U.S. Chemical Safety Board, 2006; Yuan et al., 2015). However, despite these data, the textile industry has in fact suffered from some very severe dust explosions over the years, with fatalities, monetary losses and serious damage (Bowen, 1988; Eckhoff, 2003; Marmo, 2010; Piccinini, 2008; Salatino et al., 2012).The textile industry deals with “non-traditional dusts”, which mainly originate from fibrous materials as a result of fragmentation and abrasion. There is still very little knowledge about the explosion properties of textile fibers, as fibers have only recently been explicitly included in the list of materials considered dangerous through technical standards that regulate the protection from explosions of industrial processes. This lack of knowledge is demonstrated, from a practical point of view, by the scarce amount of data on textile fibers available in such databases as the well-known one (GESTIS-DUST-EX) by the Institut fuer Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung (IFA).The main aim of this work was to enlarge the knowledge on hazards related to textile-derived dusts. To this aim, an extensive survey has been carried out, in cooperation with a local federation of textile employers in a northern Italian district, on the characteristics of the dusts that are present as by-products. More than one hundred dust samples were collected from several industrial sites and from different processes. Some of these industries were part of the wool manufacturing chain, while others operated in the field of natural or synthetic fibers.The samples were analyzed to determine the particle size distribution. Wet-sieving and/or laser diffraction methods were used, depending on the nature of the sample. Twenty-two samples were submitted to the speditive explosibility test (SET), which was developed at the Politecnico di Torino (Danzi et al., 2016), and of these samples, 21 were found to be explosible. The samples, including those which were negative to SET, were submitted to a traditional test in a 20 l sphere to measure the maximum pressure (Pmax) and the deflagration index (KST). The minimum ignition energy (MIE) was measured with a Mike 3 device. Chemical and morphological characterizations of these samples were also performed.A discussion on the explosion risk in textile processes can be made on the basis of the obtained results. Details of the experimental program and all the obtained results are described in the paper.

Risk of Dust Explosions and Safety Measures for Them

Risk of Dust Explosions and Safety Measures for Them

Numerical Simulation on Smoke Spread and Temperature Distribution in a Corn Starch Explosion

It is discovered from dust explosion accidents in recent years that deep causes of the accidents lies in insufficient cognition of dust explosion danger, and no understanding on danger and information of the dust explosion. In the study, Fire Dynamics Simulator (FDS) evaluation tool is used aiming at Taiwan Formosa Fun Coast explosion accidents. The calculator is used for rebuilding the explosion situation. The factors affecting casualties under explosion are studied. The injured personnel participating in the party are evaluated according to smoke diffusion and temperature distribution for numerical simulation results. Some problems noted in the fire disaster after actual explosion are proposed, rational site analysis is given, thereby reducing dust explosion risk grade.

Explosion Characteristics of Torrefied Wheat Straw, Rape Straw, and Vine Shoots Fuels

Torrefaction is a method for upgrading raw biomass to produce solid fuels that exhibit higher energy density relative to that of the raw material. In countries that produce significant amounts of agricultural residues, torrefaction may facilitate the utilization of waste in the energy sector by adding value to the raw fuel and opening pathways for new applications. In typical scenarios for utilization as fuel, both the raw and torrefied materials are stored in granular form. Dependent upon the properties of the granular material, the risk of dust explosion may be significant. Torrefaction changes the physical and chemical properties of the biomass and, therefore, affect explosion risk and severity. This work investigates the dust explosion characteristics of raw and torrefied agricultural wastes typically produced in Central European countries. The objective is to provide a characterization of these fuels in terms of explosion properties and make recommendations on storage design and safety. Three residue...

A novel method of fuzzy fault tree analysis combined with VB program to identify and assess the risk of coal dust explosions.

Coal dust explosions (CDE) are one of the main threats to the occupational safety of coal miners. Aiming to identify and assess the risk of CDE, this paper proposes a novel method of fuzzy fault tree analysis combined with the Visual Basic (VB) program. In this methodology, various potential causes of the CDE are identified and a CDE fault tree is constructed. To overcome drawbacks from the lack of exact probability data for the basic events, fuzzy set theory is employed and the probability data of each basic event is treated as intuitionistic trapezoidal fuzzy numbers. In addition, a new approach for calculating the weighting of each expert is also introduced in this paper to reduce the error during the expert elicitation process. Specifically, an in-depth quantitative analysis of the fuzzy fault tree, such as the importance measure of the basic events and the cut sets, and the CDE occurrence probability is given to assess the explosion risk and acquire more details of the CDE. The VB program is applied to simplify the analysis process. A case study and analysis is provided to illustrate the effectiveness of this proposed method, and some suggestions are given to take preventive measures in advance and avoid CDE accidents.

Assessment of dust explosions in the sugar industry with regard to screening technology

The prevention of dust explosions is a necessary treatment to ensure the safe operation of sugar plants worldwide. Especially in the field of screening technology only few mistakes can lead to hazardous process conditions. This paper discusses the principles of sugar dust explosions with special focus on their formation. An example is given to show possible threats which can occur during production. Advices for choosing suitable process parameters and equipment are given. A professional dust control is key to decrease the risk of dust explosions.

Partial inerting of dust clouds using a modified standard minimum ignition energy device

Partial inerting is an important but underutilized mitigation technique in which minimum ignition energy (MIE) of a dust cloud is increased through inerting, reducing the risk of an accidental dust explosion or more accurately, a dust deflagration. This technique has wide application potential in numerous chemical and general manufacturing industries. The Kühner MIKE3 is the predominant apparatus for measurement of the minimum ignition energy (MIE) of combustible dusts worldwide. The current version of the MIKE3 device is not specifically designed to measure partial inerting minimum ignition energies. The purpose of this work is to demonstrate that a properly designed add on purge device and technique can accurately produce partial inerting MIE results with an existing MIE device.The purge device ensures complete purging of the Hartman dust dispersion tube with the desired gas concentration before experimentation. The same gas is then pulsed into the dispersion tube producing the dust dispersion for ignition testing. This approach leads to uniform testing conditions in the tube with respect to gas concentration which is essential for producing proper measurements. Additionally, experiments show the turbulence generated by the purging technique did not significantly affect the MIE measurements. Therefore, an important finding of this work is that purging the tube before partial inerting MIE testing results in a proper characterization of the relationship between the MIE and oxygen for the dust. The findings therefore demonstrate the need to amend existing or develop new standards for this type of dust testing. The effect of these modifications and techniques are demonstrated by the experimental determination of the partial inerting curve for Niacin (CaRo15) using the Kühner MIKE3 apparatus.

Ultrasonically dispersed dyed water mists as a substitute for colored powders

Colored powders such as colored corn starch are used in events such as The Color Run to blanket the air and surroundings with decorative color. Their use, however, presents a risk of dust explosion. The fact that such powders are used at events drawing large crowds makes any fire or explosion likely to result in a mass casualty incident. For instance, the Formosa Fun Coast explosion on June 27, 2015, resulted in multiple deaths and injuries. Development of alternatives to flammable/explosive colored powders would eliminate this hazard. We demonstrate as a proof-of-concept that an ultrasonically driven water mist can produce effects similar to those created by colored powders. Food coloring was dissolved in water, and the colored water was subsequently dispersed from various ultrasonic devices and photographed. Colored clouds were formed from the colored water. Colored clouds were visible under various conditions, and color combinations were possible. Possible risks of colored corn starch and water mists are discussed. An ultrasonic misting system is capable of safely replacing colored powders with regard to appearance.

Assessing the explosive dust concentration and explosion risk in Shahroud high-risk industries

Assessing the explosive dust concentration and explosion risk in Shahroud high-risk industries