A centrifugal separator for cleaning gas containing contaminants including a stationary casing, enclosing a separation space through which a gas flow is permitted, said stationary casing comprising a surrounding side wall, an upper end wall and a lower end wall, a gas inlet extending through the stationary casing and permitting supply of the gas to be cleaned, a rotating member comprising a plurality of separation members arranged in said separation space and being arranged to rotate around an axis of rotation, a gas outlet arranged in the stationary casing and configured to permit discharge of cleaned gas and comprising an outlet opening through a wall of the stationary casing, a drainage outlet arranged in a lower portion of the stationary casing and configured to permit discharge of liquid contaminants separated from the gas to be cleaned, a drive member for rotating the rotating member, wherein the centrifugal separator further comprises at least one guiding vane arranged for guiding separated liquid impurities on the inner surface of the lower end wall from a radial outer position to the drainage outlet.