Experimental and theoretical investigation of the lower explosion limit of multiphase hybrid mixtures

Abstract

This article reports on experimental and theoretical investigations of the lower explosion limits of two‐ and three‐phase mixtures such as gas‐dust, spray‐gas, dust‐spray, and dust‐gas‐spray. The materials used were lycopodium and brown coal as combustible dusts, methane, and hydrogen as combustible gases and ethanol and isopropanol as sprays (liquid solvent).The experiments were performed in the standardized 20‐L spherical explosion chamber where modifications were done to allow the input of solvents and gases. The test protocol was in accordance with the European standard, EN 14034. The experimental results demonstrate significant enhancements in explosion likelihood brought about by gas or spray admixture with dust and vice versa. They also confirm that a hybrid mixture explosion is possible even when both dust and spray or gas concentrations are respectively lower than their minimum explosible concentration (MEC) and lower explosion limit (LEL). For example, the MEC of brown coal decreases from 250 to 60 g/m3, 60 and 100 g/m3 when small amounts of isopropanol spray, methane gas, and hydrogen gas respectively, were added (even though these concentrations of gases and solvents are all below the LEL of the individual substances).Comparisons have been made between the lower explosible limit of the experimental data and classical models such as those developed by Bartknecht, Le Chatelier, and Jiang and coworkers. This research provides safety practitioners with a practical means to characterize material hazards without the need to perform a large number of tests. © 2019 American Institute of Chemical Engineers Process Saf Prog, 1–13: e12045 2019