Influence of turbulence flow on explosion characteristics of coal dust in 20 L vessel

The measurement of transient turbulent flow and coal dust explosion parameters were carried out in a 20 L cylindrical tank of transparent organic glass and an iron explosion experiment tank with two sets of pneumatic dispers-ed system,respectively. The turbulence characteristics and explosion parameters were studied under pneumatic pres-sures of 0. 4-0. 8 MPa. The results show that under different pneumatic pressures,the Urms is in the range of 1． 1- 6． 2 m / s,the average turbulence integral scale is in the range of 40-72 mm,and Reynolds number is 8 000-16 300 in 100-250 ms. The explosion peak-pressure is linear in the range of 1. 1-6. 2 m / s and increases from 0． 78 MPa to 1． 17 MPa. The increase of the dP / dt max is obvious within a relative low velocity Urms of 1. 1-3. 5 m / s,and the in-crease of the dP / dt max is slowing down in Urms of 3. 5-6. 2 m / s. Although larger turbulence intensity accelerates the blend and reaction of coal dust with air fully,it can also lead to a decrease in the efficiency of heat transfer and mass transfer between coal powder particles. By using the theory of ueff,max ,the result is consistent with the dynamic change trend of the explosion intensity.