The present contribution summarizes research related to the numerical computation of pneumatic conveying systems applying the Euler/Lagrange approach. For that purpose, a rigorous modelling of the particulate phase was aspired, including the relevant fluid dynamic forces, particle-wall collisions with wall roughness and inter-particle collisions. For the validation of the computations, experiments of Huber and Sommerfeld were selected for the conveying through a 80mm stainless steel pipe with 5m horizontal pipe, bend and 5m vertical pipe. The majority of the computations were done for the same pipe system; however, in this instance, consisting of 150mm stainless steel pipes. In these cases the average conveying velocity was 27m/s and the particle mass loading was 0.3 (mass flow rate of particles/mass flow rate of air). For this configuration the influence of wall roughness, inter-particle collisions, particle size, and mass loading on the resulting particle concentration distribution, the secondary flow as well as the pressure drop in the different pipe elements was analyzed. Moreover, a segregation parameter was defined which describes the location of the maximum particle concentration throughout the pipe system. The secondary flow intensity (SFI) was used to characterize the influence of the particle phase on the developing structure of the secondary flow.