Patent ID: 7485084

Claim:
A centrifugal separator for separation of a product in a least a relatively heavy phase and a relatively light phase, wherein the centrifugal separator comprises: a centrifuge rotor, which is rotatable around an axis (x) of rotation and comprises a rotor wall that encloses a separation space, which has a radially outer part, in which the heavy phase separated during operation is collected, and a radially inner part, in which the light phase separated during operation is collected, wherein the separation space has a central gas-filled space against which the collected separated light phase forms a free liquid surface and wherein the radially outer part is separated from the radially inner part by an interface layer level formed during operation, an inlet, which extends into the separation space through the rotor wall and is arranged to permit during operation feeding of the product to the separation space, a first outlet, which extends from the radially outer part through the rotor wall and is arranged to permit during operation discharge of the heavy phase through the first outlet, a second outlet, which extends from the radially inner part through the rotor wall and is arranged to permit during operation discharge of the light phase through the second outlet, and control equipment, arranged to permit during operation control of the interface layer level to a desired radial position by controlling the counter pressure in a least one of the first outlet and the second outlet, the centrifugal separator being designed in such a way that the separation space is closed to an environment and permits maintaining of a gas pressure in the central gas-filled space of the separation space, which gas pressure deviates from the pressure of the environment, a sensor for sensing, during operation, a parameter that is related to the gas pressure in the central gas-filled space of the separation space and which is connected to the control equipment, and the control equipment being arranged to control the counter pressure in at least one of the first outlet and the second outlet in response to the sensed parameter for controlling the interface layer level to the desired radial position.