Reducing gas hold-up has been identified as a key objective to improve the performance of Syncrude's LC-Finer(SM) unit. Redesign of the liquid recycle pan in the freeboard region, aided by multiphase CFD simulation and tests in a kerosene cold model experimental system, led to reduced gas hold-ups. The addition of an anti-foam agent did not provide any improvement. Cold-flow dimensional similitude tests demonstrated the importance of gas density, distributor geometry, and interfacial phenomena. Grid redesign was undertaken to diminish swirl and provide improved radial distribution of gas. Dispersion tests indicate favourable catalyst mixing in the reactors.