Cyclone pressure drop reduction and its effect on gas–particle separation capability: principle, performance, and assessment

Cyclone separators have been widely used for gas–particle separation in chemical engineering. However, their enhancement in separation performances usually increases the pressure drop, which inevitably leads to an increase in operating energy consumption. One of the challenging issues is how to reduce the cyclone pressure drop while improving separation performances. To gain insight into the pathways and impacts of cyclone pressure drop reduction, this work reviews the state-of-the-art technical principles, performances and effects, focusing on the processes, mechanisms, and characteristics of pressure drop reduction by inlet/outlet variations, additional auxiliary devices, local cyclone dimension improvement, and global optimization based on intelligent algorithms. The cyclone performances are assessed using a proposed index that combines the Euler number and the square-root particle cut-off Stokes number. It is suggested that the pressure drop and separation capability usually have a dynamic compromise. Considering the comprehensive performances, the technology using helical roof inlet, cross cone, increasing cylindrical height with h/D = 4.3 (H/D = 6.35), and globally optimized design by Sun et al. (2017) are respectively considered to the others. Particularly, the last one is recommended to be more representative in practice. Finally, the key issues to be considered in further research were also prospected.