Study on Explosion and Venting Characteristics of Ethanol Mist

Due to the low flash point and high vapor pressure of ethanol, serious combustion and explosion accidents are readily triggered during industrial storage and transportation. Explosion venting is therefore regarded as a critical safety protection measure. To reveal the explosion venting characteristics of ethanol mist and provide experimental guidance for industrial venting design, a comprehensive experimental platform was established based on a 20 L spherical explosion vessel, integrating mist dispersion, ignition, pressure and flame acquisition, and explosion venting units. Explosion and venting experiments of ethanol were conducted under a concentration range of 0~800 g/m³, with three different vent diameters and six distinct static activation pressures. The results show that an ethanol mist concentration of 500 g/m³ produces the most severe explosion under the experimental conditions investigated, with a maximum explosion pressure of 0.79 MPa and a peak explosion index of 34.8 MPa·m/s. It is clearly found that increasing the static activation pressure and reducing the venting diameter lead to higher explosion pressures and suppressed flame propagation. When the static activation pressure is increased from 320.22 kPa to 426.96 kPa, the maximum explosion pressure is increased by 31.9%, while the average flame propagation velocity is reduced by 25.5%. When the venting diameter is enlarged from 60 mm to 100 mm, the maximum flame propagation velocity is increased by 15.3%. A smaller venting diameter results in a more elongated flame jet with concentrated sparks, whereas a higher static activation pressure delays the flame appearance time and increases spark generation. Based on the experimental data, the venting area equation specified in the NFPA 68 standard is modified, and a venting area model applicable to ethanol mist explosions is established. The findings provide valuable experimental evidence and data support for the optimization and design of explosion venting systems in the industrial storage and transportation of ethanol.