The invention in one embodiment is a nozzle device for coupling with a fluid distribution conduit for improving the distribution of an upward or downwardly flowing poly-phase mixture including at least one gas phase and at least one liquid phase, above at least one packed bed of granular solid or fluidized bed. The fluid distribution conduit for receiving liquid and gas phases has one or more lateral openings for flow over an upper portion of its height through which a gas phase can enter and has fluid distribution conduit having one or more lateral openings for flow over at least a lower portion of its height through which a liquid phase can enter the fluid distribution conduit. It also has at least one lower cross section for flow through which a mixture of gas and liquid communicate with a packed bed of granular solid or a fluidized bed. The nozzle device includes a venturi nozzle having an outer diameter not greater than an inner diameter of the lower cross section of the fluid distribution conduit, wherein the nozzle device may be fixedly coupled to and co-axially aligned with the lower cross section of the fluid distribution conduit. It is for accelerating and dispersing the liquid and gas phases passing out of the conduit.