Characteristics of gas-solid two-phase flow in axial and swirling flow pneumatic conveying

摘要

To improve the capacity and efficiency of pneumatic conveying systems, a swirling flow generator was developed to achieve swirling flow pneumatic conveying (SFPC) for particles. A numerical simulation of axial flow pneumatic conveying (AFPC) and swirling flow pneumatic conveying (SFPC) for particles was carried out using the Lagrange particle tracking method (LPTM), in which the interactions of the gas phase and solid phase were taken into account. The distributions of particle concentration and particle velocity were analysed. The results indicate that the distribution of particle concentration was improved by swirling flow and that of the particle velocity increased first and then decreased with swirling flow intensity; however, the particle velocity still increased by more than 40 % relative to the velocity observed in AFPC. Swirling flow exhibited the optimal behaviour when the swirling intensity was approximately 0,3. The swirling intensity decayed faster with greater axial gas velocity exponentially. The results of pressure loss experiments in AFPC and SFPC showed that there was an optimal gas velocity in AFPC that minimised the pressure loss. The optimal gas velocity increased with mass flow rate; the pressure loss in SFPC first increased and then decreased with swirling intensity. The maximum pressure loss in SFPC was larger than that in AFPC while the swirling intensity was 0,35; 0,376; 0,38 and the mass flow rate was 1,5 kg/s; 1,9 kg/s; 2,5 kg/s. The pressure loss in SFPC was lower than that in AFPC while swirling intensity was higher than a certain value.