The invention relates to a centrifugal separator comprising a rotor arranged to be rotatable around an axis of rotation (x). An inlet chamber is formed in the rotor and an inlet pipe extends into the rotor and has an opening in the inlet chamber for supply of a liquid mixture of components. An inlet arrangement is provided in the inlet chamber, comprising a set of annular discs coaxial with the rotor and forming passages for liquid between the discs, or a helically shaped element coaxial with the rotor and forming passages for liquid between the windings of the helically shaped element. The separator further comprises vanes arranged upstream of the inlet arrangement such as to cause a pre-rotation and pre-acceleration of the liquid mixture. The vanes may be provided on a removable element of the rotor.