A centrifugal separator of the kind described is shown for instance in the Swedish Patent No. 19 666 from 1904. IT is unknown whether a centrifugal separator of this kind has been produced and used. From the turn of the century and thereafter the inlet of the separation chamber in centrifugal separators of this kind has been situated at the end of the separation chamber, towards which the base portions of the separation discs face. A conventional centrifugal separator of this kind is shown for instance in U.S. Pat. No. 3.986.663.
A principle advantage of a centrifugal separator, in which a mixture is conducted into the separation chamber at the end, toward which the apex portion of the separation discs face, is that the result of a pre-separation taking place in said inlet passages before the mixture has entered the separation chamber, can be taken maximum advantage of. Thus, a part of a relatively heavy component of the mixture, for instance solids, may be separated even as the mixture is on its way through said inlet passages extending between the central inlet chamber and the inlet of the separation chamber.
Relatively heavy components of the supplied mixture, separated in the inlet passages, may slide along the outer walls of the inlet passages directly into the outermost part of the separation chamber, radially outside the separation discs, without being disturbed by or disturbing the rest of the mixture when this flows into the separation chamber.
In a conventional centrifugal separator, in which the liquid mixture is instead introduced through inlet passages at the end of the base portion of the separation chamber, towards which the base portions of the separation discs face (see for instance U.S. Pat. No. 3.986.663), a relatively heavy component of the mixture, separated in the inlet passages, is forced to cross the flow of the rest of the mixture where the latter enters the separation chamber. This is a consequence of the fact that the inlet passages have an inclination relative to the rotor axis just about that of the conical separation discs. Thereby the result of the pre-separation in the inlet passages is spoiled wholly or partly. This undesired effect of the cross flow will become greatest when the mixture in its entirety is introduced into the separation chamber at the outer edge of the separation disc situated closest to the inlet passages.
A possible reason why the design known already in 1904 has not been generally accepted may have been practical difficulties with the sealing within the centrifuge rotor between the crossing flows of liquid mixture on the way into and separated liquid component on the way out of the separation chamber. In the known design the previously mentioned partition member is axially movable relative to a central column in the rotor body, against which it should seal radially at its inner edge during operation of the rotor. The inner edge of the partition member and, thus, the sealing place are situated very close to the outlet of the separation chamber for separated liquid component. Since the partition member has to be separated from the column each time the centrifuge rotor is disassembled for removal of separated sludge from the separation chamber, difficulties may arise with the sealing between the column and the partition member. Leakage of inflowing mixture to outflowing separated liquid will of course destroy the separation result.