Centrifugal separators and separation methods providing intermediate material ejection control

A method including:

• (a) rotating a drum assembly of a centrifugal separator at a separator velocity about a separator rotational axis, the drum assembly including a separator volume in fluid communication with a feed inlet to the separator volume and further including a drum ejection passage, the centrifugal separator further including a drum ejection passage control element mounted on the drum assembly for movement between a first drum ejection passage control position and a second drum ejection passage control position, wherein in the first drum ejection passage control position the drum ejection passage control element is positioned relative to the drum ejection passage to define a first flow area through the drum ejection passage from the separator volume to an area outside the separator volume and wherein in the second drum ejection passage control position the drum ejection passage control element is positioned relative to the drum ejection passage to define a second flow area through the drum ejection passage greater than the first flow area through the drum ejection passage to enable material from a maximum diameter of the separator volume to be ejected from the separator volume through the drum ejection passage when the drum ejection passage control element is in the second drum ejection passage control position;
• (b) while rotating the drum assembly at the separator velocity, moving an intermediate ejection control element mounted on the drum assembly from a first intermediate ejection control position to a second intermediate ejection control position relative to an intermediate ejection path included in the drum assembly, the intermediate ejection path extending from an intermediate ejection path inlet which is radially inward of the maximum diameter of the separator volume to an intermediate ejection path outlet, wherein in the first intermediate ejection control position the intermediate ejection control element is positioned relative to the intermediate ejection path to define a first flow area through the intermediate ejection path and wherein in the second intermediate ejection control position the intermediate ejection control element is positioned relative to the intermediate ejection path to define a second flow area through the intermediate ejection path greater than the first flow area through the intermediate ejection path;
• and
• (c) while rotating the drum assembly at the separator velocity, returning the intermediate ejection control element from the second intermediate ejection control position to the first intermediate ejection control position.