Centrifugal separator for separating a liquid mixture, and method therefor

A centrifugal separator for separating a liquid mixture, the separator comprising:

• a frame which delimits a space that is sealed relative to the surroundings of the frame and in which a centrifuge rotor is arranged,
• a drive member configured to rotate the centrifuge rotor in relation to the frame around an axis of rotation, wherein the centrifuge rotor encloses a separation chamber that is arranged to receive the supply of liquid mixture to be separated via an inlet and in which separation of the liquid mixture takes place during operation,
• at least one liquid outlet for discharging a separated liquid phase,
• at least one sludge outlet arranged at the periphery of the centrifuge rotor for intermittently discharging a separated sludge component to the space delimited by the frame,
• a pump device arranged for removing gas to obtain sub-atmospheric pressure in the space during operation,
• a measuring unit arranged to measure the sub-atmospheric pressure Px in the space during operation, and
• a control unit configured to
• receive a value of the sub-atmospheric pressure Px from the measuring unit, and to
• initiate discharge of the separated sludge component via the at least one sludge outlet when the received value Px is within a preset pressure interval ΔP, and
• supply liquid to a seal that seals the space relative to the surroundings of the frame before initiating the discharge of the separated sludge component via the at least one outlet.