FI59277C - ANORDNING FOER RENING AV FIBERSUSPENSIONER - Google Patents

Description

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Patent- och raglatoratyrtiMn '' Arastan uthcd och utUkiifcm pubiieMd 31-03.81 (32) (33) (31) FyH *** r «« »Itara -» ** lnl prtorKcc (71) A. Ahlström Osakeyhtiö, Noormarkku, Suomi- Finland (FI) (72) Johan Gullichsen, Siuntio, Finland-Finland (Fl) (5U) Apparatus for cleaning fiber suspensions - Anordning för rening av fibersuspensioner (62) Divided by application 781789 - Avdelad fr & n an-sökan 781789

The present invention relates to an apparatus for purifying flowing high-density fiber suspensions, in particular in connection with the production of cellulosic pulps.

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Cleaning of fiber suspensions in the pulp industry is performed! »Usually at a consistency of 0.5 to 5%. Because of mass production! other processes take place at higher consistencies, e.g. 8-12%, j this means that the pulp must first be diluted for processing and then re-thickened. This requires a lot of power and requires supportive equipment. Nevertheless, treatment can lead to an inhomogeneous result.

The object of the invention is to provide a device by means of which a fiber suspension with a consistency of 5 to 25% can be purified. It is also an object of the invention to provide reliable and simple devices with low power requirements.

This is achieved by causing the fiber suspension to flow between the surfaces where it is subjected to repetitive, opposite direction changes and shear forces greater than the forces cohesive of the fiber network so that it is fluidized and removed while in the fluidized state.

The invention is based on the fact that when the fiber suspension is subjected to sufficiently high shear forces, it fluidizes, i.e. changes easily into a fluid form, whereby the fibers in it move relative to each other. In this case, for example, particles of different weights or sizes can be easily separated from one another. Since the treatment can be performed when the fiber suspension is very thick, the power consumption calculated for the fibrous material is small. There are protrusions and / or recesses on both surfaces between which the fiber suspension flows. As a result, the fiber suspension stream can be fluidized without having to use large velocity differences between surfaces. By properly dimensioning and shaping the protrusions and recesses of the surfaces, directionally changing flows deviating from the main flow direction of the fiber suspension are obtained such that the entire fiber suspension stream fluidizes even if the distance between the surfaces is large.

The vortex cleaners have, as is apparent from German patent application OS 24 23 528, a rotor with a rotating blade previously used in a cylindrical housing. However, the device is intended for low consistency.

For a device according to the invention, comprising a hollow rotor with external, mainly longitudinal ribs, a housing surrounding the rotor, the upper part of which is fitted with an inlet pipe for the fibrous suspension to be cleaned and a downwardly tapering conical lower end with an abandoned fraction a combined impeller and to which an approved fraction outlet pipe is connected, is characterized in that it comprises a fluidization zone delimited by the inner surfaces of the cylindrical upper and conical lower parts with substantially longitudinal ribs and the outer surface of the rotor.

The invention will now be described in more detail with reference to the accompanying drawing, in which Figure 1 shows an apparatus for cleaning a fiber suspension and Figure 2 shows a section along the line J-J in Figure 1.

The vortex cleaner shown in Figures 1 and 2 includes a housing 70, the upper portion 71 of which is cylindrical and the lower portion 72 is in the shape of a downwardly tapering cone. The cylindrical part of the housing has an inlet pipe 73 for the fiber suspension to be cleaned. At the lower end of the lower part of the housing there is an outlet pipe 87 to which a valve 74 is connected, through which the separated particles can be removed. Connected to the top of the housing is a pump housing 75 with a tangentially accepted fraction outlet pipe 76. A rotating impeller 78 in the pump housing and a rotating rotor 79 in the vortex cleaner housing 70 are mounted on the drive shaft 77. A rod 80 is mounted inside the rotor at its lower end. The housing has inner fins 81, the rotor has inner and outer fins 82 and 83, and the rod has outer fins 84.

The fiber suspension is fed to a fluidization zone 85 outside the rotor, bounded by the inner surface 88 of the housing and the outer surface 89 of the rotor, where it is vortexed and fluidized by the interaction of the surfaces of the high speed rotating rotor and the stationary housing. As a result of the centrifugal force caused by the vortex movement, the higher density particles move from the fiber suspension near the wall of the housing, from where they are carried by a downward flow to the lower end of the conical part of the housing, where they are removed fluded through valve 74. The approved fraction flows into the fluidization zone formed by the inner surface of the rotor inside the rotor and the outer surface of the rod ifM'i i ..

4,5277 through the impeller 86 to the impeller by means of which it is removed through the opening 76.

Experiments have shown that the fluidization channel should be 10 to 150 mm high, the most suitable height being 30 to 60 mm. The height of the U1 machines should be 0.1 to 0.3 parts of the height of the duct. The distance between the protrusions in the flow direction should be 2-50 times greater than their height, preferably 5-20 times. The speed of the moving surface should be 5-30 m / s, preferably higher than 10 m / s; the most suitable speed is about 20 m / s.

The power consumption of the vortex cleaner according to Figures 1 and 2 at a consistency of 12% is about 4 kWh / t. The power consumption of a conventional vortex cleaner at a consistency of 1% is approx. 8 kWh / t.

The invention is not limited to the embodiment shown, but numerous modifications may be made thereof without departing from the scope of the claims. The shape of the surfaces of the fluidization zones may differ from that shown in the figures by way of example.

Claims (2)

59277 5 Claim ί A vortex cleaner for high-density fiber suspensions comprising a hollow rotor with external, predominantly longitudinal ribs, a housing surrounding the rotor, the upper end of which is fitted with an inlet pipe for the fibrous suspension to be cleaned and the downwardly tapered conical a housing with an impeller connected to the rotor and to which an approved fraction outlet pipe is connected, characterized in that it comprises a fluidizing zone (85) delimited by the inner surfaces (88) of the substantially longitudinal ribs (81) and the outer surface (89) of the rotor (79) ). ‘I