Abstract: Water present in a hot gaseous product stream from a reactor system A,B (FIG. 1 ) containing hydrogen fluoride is separated from the stream in order to eliminate a potentially corrosive combination of water and HF. The water is removed by contacting the gaseous product stream with liquid HF in a distillation column so as to obtain a bottoms product containing liquid HF and water and a top product containing dry HF and the product to be recovered. The invention encompasses the separation process, a vessel for carrying out the process (FIGS. 2 to 4), a control system for the liquid HF supply to the distillation column (FIGS. 5 and 6) and a recovery system for recovering HF employed during operation of the reactor system in different regimes employing HF as a fluorination agent, as a diluent during catalyst regeneration and/or catalyst prefluorination (FIG. 7 ).

Abstract: A gas-liquid contact apparatus includes a rotor having an outer wall parallel to the axis of rotation of the rotor, a permeable element mounted within the rotor for rotation therewith, inlets to supply liquid and gas to the rotor and outlets for conducting a gas and liquid respectively from the rotor. The permeable element is made of a plurality of strips of permeable material in layers superimposed progressively from the outer wall inwards towards the axis of rotation, the strips being in end-to-end abutment and the abutments being circumferentially staggered in adjacent layers.