A. Ahlstrom Osakeyhtio

A. Ahlstroom Osakeyhtio

Frey Viking Sundman

Toivo J Niskanen

Johan E Gullichsen

Jorma A Tuomaala

An apparatus for fiberizing and screening of fibrous material, which comprises of a rotating drum (1) the drum wall (2) of which consists of a non-perforated (7) and a perforated (8) part. The non-perforated part in the inlet end of the drum is separated from the perforated part in the outlet end of the drum by means of a partition wall (9) having an opening (10). The height (h) of the partition wall varies so that a periodical overflow is achieved when the drum rotates.

Apparatus for fiberizing and screening of fibrous materials

A process for washing fibre stock. The fibre stock is described is passed along a passage 14 from a stock inlet 15 to a stock outlet 16. The passage is defined by a portion of the inner surface of a substantially horizontal cylindrical screen 4, preferably a wire gauze. Washing liquid such as water is introduced into the passage, preferably by means of apertures 9 in a longitudinally extending hollow member 8. Effluent liquid passes through the screen, for extraction e.g. through outlets 24 and 25. To enable the washing of stock of high consistency e.g. up to 8%, while avoiding plugging of the screen 4, the arrangement is such that the stock only partially fills the cylindrical screen and is subjected to a tumbling action by the rotary movement of the cylindrical screen as the stock moves along the passage 14 to the stock outlet 16. The hollow member 8 is displaced downwardly from the axis of the cylindrical screen, so as to be positioned within the tumbling stock. In an alternative arrangement, the screen is defined by an endless belt carried over a series of rollers and having a portion of upwardly concave cross-section.

Process for washing fibre stock

A process and apparatus for washing fibre stock. The fibre stock is passed along a passage 14 from a stock inlet 15 to a stock outlet 16. The passage is defined by a portion of the inner surface of a substantially horizontal cylindrical screen 4, preferably a wire gauze. Washing liquid such as water is introduced into the passage, preferably by means of apertures 9 in a longitudinally extending hollow member 8. Effluent liquid passes through the screen, for extraction e.g. through outlets 24 and 25. To enable the washing of stock of high consistency e.g. up to 8%, while avoiding plugging of the screen 4, the arrangement is such that the stock only partially fills the cylindrical screen and is subjected to a tumbling action by the rotary movement of the cylindrical screen as the stock moves along the passage 14 to the stock outlet 16. The hollow member 8 is displaced downwardly from the axis of the cylindrical screen, so as to be positioned within the tumbling stock. In an alternative arrangement, the screen is defined by an endless belt carried over a series of rollers and having a portion of upwardly concave cross-section.

Apparatus for washing fibre stock

Press for removing water, wherein the material to be treated is led together with a wire which is pervious to water through a press nip zone formed by opposite surfaces. The press comprises compressible means for transporting the material to be treated. This means runs through the press nip and comprises several compression chambers which open out against the wire pervious to water. The compression chambers are preferably made so that they expand towards the water transmitting wire or felt, e.g. like a truncated pyramid.

Press for removing water

The disclosure describes a method and a device for pumping fiber suspensions of high consistency. Shear forces disrupting fiber flocs are induced near the front edge of the vanes of the impeller in a centrifugal pump which fluidize the fiber suspension hereby converting it into an easily pumpable state. This is effected by an inlet part having recesses and/or lobes in its inner surface in front of the impeller which cooperate with a rotor having an outer surface in which there are recesses and/or lobes disposed into the inlet part.

Method and apparatus for pumping fiber suspensions

A pulp containing lignocellulosic fibers is treated with chlorine in two steps. In the first step, chlorine in the amount of 0.6-0.9 grams per gram of lignin in the fibers, is mixed in the gaseous state into the pulp and in a second step the reaction products, which contain chlorinated lignin, are removed by displacing the liquid in the pulp with a chlorine solution, the amount of active chlorine in the solution in the second step being between 0.1 and 0.3 grams per gram of the lignin initially present in the pulp. In this manner 92% delignification is achieved without any intermediate washing between the two steps and with a total amount of chlorine between 0.7 and 1.2 grams per gram of lignin. The consistency of the pulp in both steps is the same and is between 6 and 12%.

Method for treatment of lignocellulosic material with chlorine

A process for bleaching cellulose pulp with molecular oxygen under alkaline conditions and at an elevated temperature in a bleaching zone is disclosed in which oxygen gas is dispersed into an alkaline bleaching solution under an increased pressure, the oxygen-containing, alkaline bleaching solution is heated to at least the elevated bleaching temperature, the pressure of the hot, oxygen-containing, alkaline bleaching solution is lowered to the pressure prevailing in the bleaching zone, and the hot, oxygen-containing, alkaline bleaching solution is brought, in the bleaching zone, into contact with the cellulose pulp to bleach the latter with the oxygen gas released from the bleaching solution.

Process for bleaching cellulose pulp with molecular oxygen

A method and apparatus for drying pulp, wherein the pulp is pre-dried to 60 to 70%, disintegrated and then formed into a layer of fibres on a moving wire which is dried by passing hot air through it to achieve a dryness of 90%. According to a preferred embodiment of the invention the layer of fibres is cooled by air compressed by press rolls after which it is cut into sheets which are piled into bales.

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Karhula, Finland

Frey Viking Sundman