A catalyst return apparatus is disclosed as well as a riser reactor system comprising the conduit apparatus and a riser reactor, the conduit apparatus comprising a catalyst return conduit and at least two flow control devices in series, each flow control device arranged to control the flow of fluid through the conduit, wherein the length of the catalyst return conduit is more than 20 m. A process for reacting a feedstock in a riser reactor system comprising a riser reactor, the catalyst return apparatus and, and a stage vessel, the process comprising: holding a fluid comprising the catalyst in the at least one stage vessel for a residence time of at least 10 seconds.