Patent ID: 8778191

Claim:
A method of filtering a fluid by means of a centrifugal filtering device, in which the device comprises an inner casing forming an inner space with an inner pressure and an outer casing forming an outer space with an outer pressure, wherein the inner casing and the outer casing are rotatable around a central axis extending through the inner casing and the outer casing, a fluid inlet configured to permit feeding of the fluid into the inner space, and at least one filter being located between the inner space and the outer space, wherein the method comprises: feeding a fluid to be filtered into the inner space by means of the fluid inlet; rotating the inner casing at a first rotational speed, thereby creating a centrifugal pressure forcing at least a part of the fluid from the inner space through the filter and to a radially outer position of the outer space, the filtered fluid forming a filtrate and the non-filtered fluid forming a concentrate, the filtrate having a rotational movement and a kinetic energy; transporting the filtrate from the radially outer position of the outer space to a radially inner position of the outer space, wherein the transporting of the filtrate from the radially outer position of the outer space to the radially inner position space transfers the kinetic energy from the filtrate to the outer casing, thereby permitting regaining of mechanical energy, and discharging the filtrate and the concentrate from the centrifugal filtering device.