In industrial fluid cokers, bitumen is first mixed with steam in a premixer, and then fed to the atomization nozzle. The objective of this work was to evaluate the Impact of both the premixer and the nozzle geometrical configuration on the quality of the liquid-solid contact resulting from injections of liquid into a gas-solid fluidized bed. To assess the quality of the liquid-solid contact a method based on electric conductance measurements of the bed material previously developed by the authors [9] was used. Liquid atomization efficiency in open air, spray geometry, and spray stability were also characterized to evaluate their effects on the nozzle spraying performance within the fluidized bed. This study indicated that spray stability is highly beneficial to the liquid-solid contact efficiency. In particular, fluid constrictions such as the series of converging and diverging sections within the nozzle have a stabilizing effect on the spray Future optimization of the existing liquid-injection systems should consider alternative gas-liquid premixers and nozzle geometries to enhance the jet stability. (C) 2010 Elsevier B.V. All rights reserved