A centrifugal separator for cleaning of a gas containing impurities in the form of solid and/or liquid particles, wherein the centrifugal separator comprises; - a stationary casing, which encloses a separation space and permits the gas to flow therethrough, wherein the stationary casing has an inner wall surface facing the separation space, - an inlet channel, which extends to the separation space and forms an inlet for the gas to be cleaned, - a rotating member, which is provided in the separation space downstream the inlet with regard to the gas flow and arranged to rotate in a direction (r) of rotation about an axis (x) of rotation, wherein the rotating member comprises a number of separation discs and a central space, and is adapted to bring the gas to rotate in the direction (r) of rotation for separating by means of centrifugal forces at least a main part of the impurities from the gas, wherein the inlet channel is a central channel extending into the central space of the rotating member, wherein the separation discs form gaps between the separation discs through which the gas to be cleaned is conveyed via the inlet channel and the central space, and wherein the separation discs form surfaces on which the particles to be separated from the gas may be cleaned and transported outwardly towards the inner wall surface, - a gas outlet channel, which with regard to the gas flow is provided downstream the rotating member for discharging the cleaned gas, and - at least a first outlet, which is provided for discharging the impurities from the separation space, wherein the centrifugal separator comprises a supply member which is configured to permit a supply of a separation aid humidifying the particles, which aid is in form of an aerosol, to the gas to be cleaned, and the supply member is arranged to permit the supply of the separation aid to the inlet channel, and to convert the separation aid supplied to the inlet channel to an aerosol, wherein the supply member comprises an aerosol nozzle through which the separation aid is supplied, characterized in that the supply member comprises a pipe element, which extends to the inlet channel and has a first end, that the first end of the pipe element is open to the inlet channel, is arranged outside the stationary casing and discharges laterally into the inlet channel, and that the aerosol nozzle is provided in the pipe element. - a stationary casing, which encloses a separation space and permits the gas to flow therethrough, wherein the stationary casing has an inner wall surface facing the separation space, - an inlet channel, which extends to the separation space and forms an inlet for the gas to be cleaned, - a rotating member, which is provided in the separation space downstream the inlet with regard to the gas flow and arranged to rotate in a direction (r) of rotation about an axis (x) of rotation, wherein the rotating member comprises a number of separation discs and a central space, and is adapted to bring the gas to rotate in the direction (r) of rotation for separating by means of centrifugal forces at least a main part of the impurities from the gas, wherein the inlet channel is a central channel extending into the central space of the rotating member, wherein the separation discs form gaps between the separation discs through which the gas to be cleaned is conveyed via the inlet channel and the central space, and wherein the separation discs form surfaces on which the particles to be separated from the gas may be cleaned and transported outwardly towards the inner wall surface, - a gas outlet channel, which with regard to the gas flow is provided downstream the rotating member for discharging the cleaned gas, and - at least a first outlet, which is provided for discharging the impurities from the separation space,