NOVELTY - An installation for the chemical conversion of a charge rich in hydrogen and carbon monoxide by a Fischer-Tropsch reaction comprises means for stopping the circulation in the external circuit (14), introducing a flushing fluid under pressure (D), and enabling circulation in conditions such that the Reynolds number is greater than 2500 at any point in the circuit.    USE - The installation is used for a conversion of synthesis gas (CO + 2H2) by a Fischer-Tropsch reaction using an iron or cobalt catalyst.    ADVANTAGE - The process is automated and the suspension is maintained without any deposition in the reactor or external circuit. The process requires little maintenance and a limited number of personnel.    DETAILED DESCRIPTION - An installation for the chemical conversion of a charge rich in hydrogen and carbon monoxide by a Fischer-Tropsch reaction comprises a reactor containing a slurry comprising a suspension of a solid in a liquid, a supply of gas to the lower part of the reactor and a circuit external to the reactor. The circuit enables a continuous circulation of the slurry with withdrawal point and re-entry points from the reactor, the latter below the former, and a separation section. The system also comprises a means for stopping the circulation in the external circuit (14), introduction of a flushing fluid under pressure (D), and enabling circulation in conditions such that the Reynolds number is greater than 2500 at any point in the circuit.    An INDEPENDENT CLAIM is also included for a process using this installation.    DESCRIPTION OF DRAWING(S) - The figure illustrates the Fischer-Tropsch installation    supply of reactive gas (1)    reactor (2)    evacuation of gaseous effluents (3)    heat exchanger (4)    gas injection points (6)    external circuit (11, 12, 13)    stop valve (14)    automated valve (15)    pump (16)    separator section (17)    hydrocarbon separator (31)    liquid/gas separator (37)    automated valves (41, 42, 43)    control system (50)    exit point from reactor (A)    re-entry point to reactor (B)    two points of connection to the liquid/gas separator for flushing of external circuit (C, D)