Dust cloud ignition by electrostatic discharges and the mythology of minimum ignition energy-do we know enough?

Abstract The ignition and explosion of coal dust are significant hazards in coal mines. In this study, the minimum ignition temperature and energy of non-stick coal dust were investigated empirically at different working conditions to identify the key factors that influence the sensitivity and characteristics of coal dust explosions. The results showed that for a given particle size, the minimum ignition temperature of the coal dust layer was inversely related to the thickness of the coal dust layer. Meanwhile, when the layer thickness was kept constant, the minimum ignition temperature of the coal dust layer decreased with smaller coal dust particle sizes. Over the range of particle sizes tested (25–75 μm), the minimum ignition temperature of the coal dust cloud gradually increased when larger particles was used. At the same particle size, the minimum ignition temperature of the coal dust layer was much lower than that of the coal dust cloud. Furthermore, the curves of minimum ignition energy all exhibited a minimum value in response to changes to single independent variables of mass concentration, ignition delay time and powder injection pressure. The interactions of these three independent variables were also examined, and the experimental results were fitted to establish a mathematical model of the minimum ignition energy of coal dust. Empirical verification demonstrated the accuracy and practicability of the model. The results of this research can provide an experimental and theoretical basis for preventing dust explosions in coal mines to enhance the safety of production.

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Sensitivity to ignition by electrostatic discharge of explosive dust / air

MATEC Web of Conferences ◽

10.1051/matecconf/201929012011 ◽

2019 ◽

Vol 290 ◽

pp. 12011 ◽

Cited By ~ 1

Author(s):

Dan Gabor ◽

Emilian Ghicioi ◽

Mihaela Părăian ◽

Niculina Vătavu ◽

Florin Adrian Păun ◽

...

Keyword(s):

Electrostatic Discharge ◽

Electrostatic Charge ◽

Explosion Hazard ◽

Explosive Mixture ◽

Ignition Energy ◽

Minimum Ignition Energy ◽

Electrostatic Discharges ◽

Industrial Sectors ◽

Surrounding Atmosphere

In industrial sectors that use, process, transport or store, substances such as combustible dusts could exist some workplaces with explosion hazard due to the possibility of dust/air explosive formation and ignition, both inside the installations and in the surrounding atmosphere. Methods and means of protection aim to prevent the development of explosive atmospheres, followed by preventing the occurrence of ignition sources and then limiting the effects of explosions. To assess the risk of ignition of the explosive atmosphere, there must be known first of all, the explosive atmosphere’s sensitivity to ignition by electrostatic discharge, respectively, the minimum ignition energy of the explosive mixture, afterwards being required an analysis on the possibilities of formation and discharge of electrostatic charge. For the most common combustible dusts, the minimum ignition energy is given, but for new types of flammable substances this parameter defining the sensitivity to ignition of the mixture by electrostatic discharges must be determined. The paper presents the results of research carried out in order to develop the methods and standards for determining the minimum ignition energy of the combustible dust / air mixture and of the methods for the assessment of the risk of ignition of the dust/air explosive atmosphere by electrostatic discharge.

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Test Method for Minimum Ignition Energy of a Dust Cloud in Air

10.1520/e2019-03r07 ◽

2007 ◽

Author(s):

Keyword(s):

Dust Cloud ◽

Test Method ◽

Ignition Energy ◽

Minimum Ignition Energy

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Aspects of laboratory tests for the determination of the minimum ignition energy of the fuel / dust mixture

MATEC Web of Conferences ◽

10.1051/matecconf/202134204004 ◽

2021 ◽

Vol 342 ◽

pp. 04004

Author(s):

Cătălin Mihai Popa ◽

Silviu Marin Nan ◽

Mihaela Părăian ◽

Adrian Jurca ◽

Florin Păun

Keyword(s):

Laboratory Tests ◽

Electrostatic Discharge ◽

Explosive Mixture ◽

Ignition Energy ◽

Minimum Ignition Energy ◽

Electrostatic Discharges ◽

Explosive Force ◽

And Storage ◽

Existing Data

During the technological processes of processing, production, handling and storage of combustible dusts, complex explosive mixtures may occur, the characteristics of which, in most cases, cannot be assimilated with the existing data in the specialized literature. If these combustible dusts are mixed with air in appropriate proportions and are initiated by an efficient source of ignition, they can burn rapidly and with considerable explosive force. One of the most common sources of ignition of potentially explosive atmospheres generated by the dust / air mixture is static electricity, materialized by electrostatic discharges. In order to assess the risk of ignition of an explosive mixture of air / dust, it is necessary to know the sensitivity of the explosive atmosphere to ignition, ie the value of the minimum ignition energy of the explosive mixture, which is then compared with the energy resulting from an electrostatic discharge. The paper presents a comparative analysis regarding the methods of determining the minimum ignition energy for air / fuel dust mixtures, using different devices, on the same type of dust.

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