Three-phase separator

Use of a three-phase separator comprising a normally horizontal vessel defining a liquid separation space and a gas space above the liquid separation space, which vessel has an inlet end space provided with a feed inlet and an outlet end space provided with separate outlets for the three phases, which vessel further comprises an inlet device comprising a primary gas-liquid separator which is arranged in the gas space and a tilted return tray arranged in the gas space under the primary separator having a lower end that is located near the inlet end wall of the vessel, such that a passage is defined between the lower end and the inlet end wall to separate a mixture of gas, oil and water into the constituents gas, oil and water.