To facilitate operation of a facility for chemical conversion of a feed that comprises a reactor (2) containing a slurry constituted by at least one suspension of at least one solid in a liquid, a gas supply, and a circuit that is external of the reactor, for continuous movement of a slurry stream, wherein the external circuit withdraws slurry from the reactor from at least one point (A) and re-introduces at least a portion of the slurry at at least one other point (B), the facility is further provided with means for stopping circulation of the slurry in the circuit; means for pressurized introduction of at least one fluid for draining the slurry contained in the circuit; and means for circulating the slurry in the external circuit under conditions such that the Reynolds number is more than 2500.