Abstract: Installation for chemical conversion of a feedstock by Fischer-Tropsch reaction comprising a reactor that contains a slurry constituted by at least one suspension of at least one solid in a liquid, a gas feed, a circuit, external to the reactor, of continuous circulation of a stream of slurry, whereby said slurry is drawn off at least one point (A) and reintroduced at least in part at least one other point (B), a section for separation of at least one slurry fluid that passes through said external circuit, whereby said installation also comprises: means allowing to shut down the circulation of said slurry in said circuit, means for introducing under pressure at least one fluid for purging the slurry that is contained in the circuit, and means allowing the circulation of the slurry in said external circuit under conditions such that the Reynolds number is greater than 2,500.