To overcome the current difficulties in designing a slurry bubble column (SBC) reactor with respect to the effect of particle properties, the influence of solid concentration (C_s) on the hydrodynamics of a SBC was studied experimentally using ultrafast electron beam X-ray tomography. The real time gas flow structure, average bubble diameter and average gas holdup as a function of the superficial gas velocity and C_s have been reported. Corresponding three-phase simulations were also performed using the Euler-Euler multi-fluid model implemented in CFX 14. The bubble size distribution was calculated using the MUSIG model. The predicted gas holdup and bubble size distribution also show dependence on U_G and C_s and agree well with the measurements. The influence of particle concentration on the gas holdup and bubble size distribution in a slurry bubble column is investigated applying the advanced non-invasive ultrafast electron beam X-ray tomography technique. Corresponding three-phase simulations are performed using the Euler-Euler multi-fluid model implemented in CFD software.