Liquids are injected into fluidized beds in a variety of industrial processes. Installing a draft tube downstream of the nozzle works to optimize the jet-bed interactions so that the liquid feed is more evenly dispersed amongst the bed solids. Triboelectric probes were used to confirm the location of the "mixing zone" inside the draft tube, and also to study the effects a draft tube had on the upstream and downstream jet boundaries. Its publication shows how the presence of a draft tube affects the expansion angle and the penetration depth of a gas-liquid jet in a fluidized bed. (c) 2008 Elsevier B.V. All rights reserved.