Effect of oxygen concentration, inert gas and CH4/H2 addition on the minimum ignition energy of coal dusts

• Published in: Journal of loss prevention in the process industries 2022-07, Vol.77, p.104772, Article 104772
• Main Authors: Wu, Dejian, Krietsch, Arne, Schmidt, Martin, Krause, Ulrich
• Format: Article
• Language: English
• Subjects: Empirical model; Hybrid mixture; Ignition energy; Inerting effect; Oxygen rich
• ISSN: 0950-4230
• DOI: 10.1016/j.jlp.2022.104772

MIKE III apparatus tests were conducted to investigate the minimum ignition energy (MIE) of coal dusts in air and O2/CO2 atmospheres with and without small amount of CH4/H2. The O2 mole fraction (XO2) in the gas mixtures varied from 21% to 50% with the CH4/H2 mole fraction from 0 to 2%. Experimental result showed that MIE of coal dusts significantly decreases even by three orders of magnitude in mJ with increasing XO2 and the addition of CH4/H2. Compared with CH4, H2 had a relatively strong promotion effect on the spark ignition of coal dusts. The inhibiting effect of CO2 was found to be much stronger than N2, but this inhibiting effect of CO2 could be eliminated by 9% increment of XO2. The effect on MIE of coal dusts thus followed by the order: 9% increment of XO2 > CO2 replacing N2 > 2% CH4 or H2 addition. Moreover, two empirical models were used to estimate the MIE of hybrid dust-gas mixture (HMIE), and the results showed that calculated data can well reflect the promoting effect of elevated XO2 and flammable gas addition, and the inhibiting effect of inert gas. •Explosion risk of coal dusts exposed to an electric spark was studied.•The effect on the MIE follows 9% increment of XO2 > replacing N2 by CO2 > 2% CH4/H2 addition.•H2 has a stronger promotion effect than CH4 on the ignition of coal dusts.•Two empirical models were used to estimate the HMIE.