Flame propagation and pressure characteristics of polymethyl methacrylate dust explosions in a horizontal pipe

Abstract

To reveal the characteristics of flame propagation and pressure in organic dust explosions during pneumatic transportation, 30 μm polymethyl methacrylate (PMMA) dust explosions with different airflow velocities were experimentally conducted in a horizontal pipe. The results showed that dust flame transited from the luminous flame with a continuous structure to discrete flames as flame propagating. After the appearance of the discrete flames, flame propagation velocity increased sharply owing to the positive feedback coupling between combustion and expansion. With the increase of dust concentration, the average flame propagation velocity, maximum flame temperature, temperature rising rate, maximum pressure, and maximum rate of pressure rise increased and then decreased. These explosion characteristics (except for the maximum flame temperature) increased significantly with the increase of airflow velocity. When airflow velocity increased from 6.39 m/s to 13.3 m/s, the peaks of average flame propagation velocity increased from 23.9 m/s to 38.2 m/s; the peaks of maximum pressure and maximum rate of pressure rise were increased by 1.9 and 6.1 times respectively. In addition, it was found that the optimum dust concentration decreased as airflow velocity increased. Furthermore, the relationship among flame propagation, temperature, and pressure was discussed in detail.