A sparger system (10) for a reactor (21) includes a feed pipe arrangement for feeding reactants to the spargers on the floor of the reactor, via a distribution system disposed above the spargers. The outlets (12) of the spargers are typically oriented towards the floor or parallel to it in order to eject gas or other reactants across the floor. This reduces settling of catalyst on the floor of the reactor, which improves mixing of the slurry and reduces the problems associated with uncontrolled reactions.