Modeling of Pneumatic Transport in the Mode of Braked Dense Layer

The process of pneumatic transport in the mode of braked dense layer is the most promising method of moving bulk materials over short distances. With its use, it would be possible to achieve the preservation of a dense layer over the whole section of the transport pipe, and also a high concentration of the solid phase in the flow, which would bring its value closer to the concentration in the fixed bed. The process of pneumatic transport in the regime of a braked dense layer was studied by methods of computational fluid dynamics. Satisfactory agreement of experimental data and calculation results with the use of DEM-particle model was established. The use of DEM method allows to solve the set problems by modeling the position of each particle in the system, which is affected by external and internal forces. A model of the motion of each particle is created, as well as the interaction of each particle-particle and particle-boundary pair, which predominantly determine the main features of the DEM motion. The results of the study confirmed that the selected model of solid particle motion adequately describes the process. The interrelation and influence of the form of braking device and the dependence of the particle motion mode on the stability of the pneumatic transport operation in the mode of braked dense layer were investigated. Change of modes (transition from the braked dense layer to the piston mode) is determined by pressure pulsations at the outlet - in the braked dense layer this parameter does not exceed 10%. According to the calculated results, it was found that the increase of simplex D0/D (i.e. decrease of compression ratio) leads to the growth of minimum gas velocity. With the increase of the diameter of the transport pipe, the value of minimum velocity slightly decreases.