Monte Carlo simulation of gas-solids suspension flows in impinging streams reactors

Abstract

Impinging streams reactors have been employed in various fields of chemical engineering, as a means of enhancing the rates of convective transfer processes. The analysis of the hydrodynamics of gas-solids suspension flows in these reactors requires that collisions between particles be taken into account. The stochastic model for gas-solids suspension flows, based on the Boltzmann transport equation, is presented. The system of nonlinear integro-differential transport equations is solved using the Monte Carlo method. A qualitative agreement is obtained between the predicted and experimental results for the particle concentration distribution in an impinging streams reactor. The particle concentrations in the impingement zone of two particle-laden jets are strongly reduced by the effects of inter-particle collisions. The analysis of laminar pipe flows in the absence of gravity and lift forces (Saffman force etc.) reveals a collision-induced migration of particles towards the pipe wall and, to a lesser extent, towards the core. In turbulent vertical pipe flow, particles migrate towards the pipe core and the laminar sublayer. Collison-induced effects become more pronounced in mixture flows with particles of different sizes and densities.