Experimental study on explosion hazard of methanol-polyvinyl alcohol two-phase system in industrial processes

Abstract

During the production, storage, and packaging of polyvinyl alcohol (PVA), methanol may volatilize to form a methanol/PVA dust two-phase system, posing a high risk of explosion. To fill the research gap on the explosion characteristics of methanol/PVA dust systems, the variation laws of explosion parameters such as the lower explosion limit (LEL), explosion intensity, and minimum ignition energy (MIE) of methanol-PVA two-phase systems at different concentrations were studied using a modified 20L explosion sphere device. The addition of methanol significantly reduced the LEL of PVA dust. When the methanol concentration increased from 0 % to 5 %, the minimum explosion concentration of PVA dust decreased from 150 g m⁻³ to 10 g m⁻³. Based on the experimental results, an empirical formula for the MIE of the gas-solid system at different methanol concentrations was proposed. The MIE of the two-phase system decreased sharply with the increase in methanol gas concentration. When the methanol content exceeded 10 %, the MIE of the two-phase system could be as low as 2–3 mJ, which is lower than the brush discharge energy commonly seen between non-metallic packaging bags and grounded metal surfaces. The explosion pressure of the two-phase system first increased and then decreased with the increase in the added methanol concentration. When the PVA dust concentration was low, the explosion pressure increased significantly. However, when the PVA dust concentration exceeds the optimal explosion concentration, the explosion pressure curve levels off, and the influence of methanol concentration on the explosion pressure of the two-phase system diminishes, with the explosion pressure increase not exceeding 0.05 MPa. The maximum rate of explosion pressure rise of the two-phase system showed a continuous upward trend with the increase in methanol concentration. The results hold significant reference value for the prevention and control of industrial dust explosions.