A new 20Â L experimental vessel for dust explosion and measurement of local concentration

To further study the distribution of local dust concentration, our work evaluated the dispersion quality of tracer particles in a new 20 L experimental vessel with a multi-nozzle injection system. Adopting the light extinction method and a high-speed camera system, local dust concentrations were obtained based on the measured optical transmittance through the dust cloud at various positions inside the 20 L vessel. Afterwards, the spatial uniformity of dust dispersion was examined using the obtained local concentrations. Based on the Lambert-Beer law, a quantitative description of dust local concentration in the upper, lower and central areas was obtained by experiment and calculation, respectively. Results show that the dust concentrations of central area in the vertical direction from top to bottom were higher than concentrations on the both left and right sides. The dust concentration on the right side near the vessel wall was slightly higher than that on the left. For two different dust dispersion durations of 20 ms and 50 ms, the local dust concentrations reached peak at 50 ms and then decreased with time due to the gravity impact on dust and turbulence intensity. In the dust cloud, the large-particle dust settles faster while the small-particle dust disperses better under the airflow action. After continuous dispersion, with the injection nozzles on two sides as the axis, dust concentration changes are symmetric between the upper and the lower areas. From analysis of dust concentrations for two dispersion durations, the variations of local dust concentrations at the selected seven measuring positions differ very little with one another. That is, the dispersion duration of 20 ms or 50 ms has little impact on the spatial uniformity of dust dispersion in the 20 L vessel.