GB1510758A - Method and apparatus for the treatment of fibrous suspensions - Google Patents

Abstract

1510758 Centrifugal separation; comminuting apparatus J M VOITH GmbH 5 Oct 1976 [30 Oct 1975] 41182/76 Headings BID B2A and B2P A suspension of fibrous material, e.g. cellulose or paper, to be purified is fed at 1 under pressure to an inlet chamber 2 of a casing in which a rotor 4 having orifices 3 is arranged for rotation; the suspension then passes through these orifices into the interior of a peripherally-imperforated drum 5 open at one end and arranged coaxially with and about the rotor 4 for rotation therewith. The rotor and drum are rotated to create a vortex 6 within the drum so as to cause heavy impurities in the suspension to move radially outwardly towards the inner surface of the drum and lighter impurities to collect in the central region of the vortex; the heavy and lighter impurities and the rest of the suspension are discharged from the open end of the drum; the heavy and lighter impurities are removed from the casing; the direction of flow of the rest of the suspension is reversed at its discharge from the open end of the drum so as to cause such suspension to flow through a filter zone 8 defined between the outer peripheral surface of the drum 5 and a filter 10 arranged coaxially with, and encircling, the drum; purified suspension which passes through the filter is removed from the casing; and impurities unable to pass through the filter are conveyed back to the inlet chamber 2. The rotor 4 may be provided with a vortex stabilizing and centering ring 21. The lighter and heavy impurities are removed from the casing through outlets 7 and 9 respectively which are fitted with closure means 18, 19 intermittently openable or controllable by the amount of impurities flowing out or by the pressure prevailing in the casing. Purified suspension is removed through an extraction outlet 11 while impurities which do not pass through the filter 10 are conveyed by obliquely disposed or helical vanes 12 on the drum towards the inlet chamber into which they are fed back by means of an annular member 13 rotating with the drum. Any large fragments in the suspension are broken down by devices 14, 15, e.g. cutters or perforated discs, mounted on the member 13 and the casing respectively. An annular chamber 16 having an outlet 17 may be provided adjacent the devices 14, 15 for collecting fragments which necessitate further breaking down.