EP0421968A2

EP0421968A2 - Conical refiner

Info

Publication number: EP0421968A2
Application number: EP90850323A
Authority: EP
Inventors: Jorma Lumiainen
Original assignee: Sunds Defibrator Jylha OY
Current assignee: Sunds Defibrator Jylha OY
Priority date: 1989-10-05
Filing date: 1990-10-01
Publication date: 1991-04-10
Also published as: FI85391C; EP0421968A3; FI894732A0; FI85391B; FI894732A

Abstract

A conical refiner for the refining of paper pulps or the like, comprising a stationary stator blade (2) and a rotating rotor blade (1), with a refining zone (6) formed between the blades so that one end of the refining zone opens to the pulp infeed side and the other end to the delivery side of the refiner. A drawback with currently used refiner constructions is that the pulp fed into the refiner is not refined uniformly, so that the pulp flowing out of the refiner contains both refined fibres and fines and unrefined fibres. In prior art, these have been screened only after the refining. In the present invention, the refiner is provided with a screening unit (4, 7) working on the principle of a pressure screen, the screen plate (4) of the screening unit being of an essentially cylindrical form and coaxial with the refiner blades (1, 2), said screening unit being fixedly connected to the stator blade and located at a desired point in the direction of the pulp flow. The rotor blade (1) has a cylindrical shape in the region of the pressure screen (4, 7) and is provided with a component (3) producing the driving power for the pressure screen.

Description

Conical refiner for the refining of paper pulps or the like, comprising a stationary stator blade and a rotating rotor blade, with a refining zone formed between the blades so that one end of the refining zone opens to the pulp infeed side and the other end to the delivery side of the refiner.
A drawback with conventional refiners is that the pulp fed into the refiner is not refined uniformly, which means that the pulp flowing out of the refiner contains both refined fibres and fines and unrefined fibres. For this reason, the pulp must be screened into different fractions to enable the unrefined fibres to be fed back into the refining process. If the screening is performed after the refining, which is usually the case in current practice, a complex process is required.
The object of the present invention is to achieve a conical refiner which is free of the drawback referred to. The conical refiner of the invention is characterized in that the refiner is provided with a screening unit working on the principle of a pressure screen, the screen plate of the screening unit being of an essentially cylindrical form and coaxial with the refiner blades, said screening unit being fixedly connected to the stator blade and located at a desired point in the direction of the pulp flow, and that the rotor blade has a cylindrical shape in the region of the pressure screen and is provided with a means producing the driving power for the pressure screen.
A preferred embodiment of the conical refiner of the invention is characterized in that the means producing the driving power for the pressure screen consists of a number of vanes.
Another preferred embodiment of the conical refiner of the invention is characterized in that the pressure screen is placed essentially at the middle of the stator blade so that it divides the refining zone into two parts.
Yet another preferred embodiment of the conical refiner of the invention is characterized in that the cylindrical part of the rotor blade is longer in the axial direction of the refiner than the screen plate.
Since the pressure screen is a fixed part of the refiner and is located at a desired point in the refining zone, the invention allows the screening to be performed during the refining.
In the following, the invention is described in detail by the aid of examples of preferred embodiments by referring to the attached drawing, presenting a vertical section through the conical refiner of the invention.
In the figure, number 1 refers to the rotor blade, which is rotated by the axle 5 of the conical refiner, said axle being connected to a driving motor (not shown). Number 2 refers to the stationary stator blade 2. The blades are coaxial. The refining zone 6 is the gap between the blades 1, 2. Paper pulp or similar fibrous matter is supplied into the conical refiner through a feed connection A, from where the pulp moves into the refining zone 6, advancing in the refining zone in the axial direction of the refiner to the delivery side.
The stator blade 2 is provided with a screening unit 4, 7 employing the principle of a pressure screen, said unit being placed at a desired level in the direction of the pulp flow. The screening unit consists of a cylindrical screen plate 4 and an essentially circular accept space 7 behind it, said space being provided with a connection B for the removal of the accepted pulp fraction. In the region of the screen plate 4, the rotor blade 1 is of a cylindrical form and provided with vanes 3 or equivalent, which serve to clean the surface of the screen plate and to take the rejected pulp fraction to the next refining stage. In the axial direction of the refiner, the vanes 3 are somewhat longer than the screen plate. After the latter refining stage, the refined pulp fraction enters the delivery space 8 of the refiner, from where it is removed via an exit connection C.
It is obvious to a person skilled in the art the invention is not restricted to the examples of its embodiments described above, but that it may instead be varied within the scope of the following claims. In the figure, the pressure screen 4, 7 is located essentially at the middle of the stator blade in the direction of the pulp flow, but it can as well be located at other positions on the stator blade. In this case, the cylindrical part of the rotor blade must be placed at a corresponding level for the pressure screen to function in the desired manner. The conical refiner can also be driven in the opposite direction, in which case the exit connection C serves as a feed connection and connection A as an exit connection.

Claims

1. Conical refiner for the refining of paper pulps or the like, comprising a stationary stator blade (2) and a rotating rotor blade (1), with a refining zone (6) formed between the blades so that one end of the refining zone opens to the pulp infeed side and the other end to the delivery side of the refiner, characterized in that the refiner is provided with a screening unit (4, 7) working on the principle of a pressure screen, the screen plate (4) of the screening unit being of an essentially cylindrical form and coaxial with the refiner blades (1, 2), said screening unit being fixedly connected to the stator blade and located at a desired point in the direction of the pulp flow, and that the rotor blade (1) has a cylindrical shape in the region of the pressure screen (4, 7) and is provided with a means (3) producing the driving power for the pressure screen.

2. Conical refiner according to claim 1,characterized in that the means producing the driving power for the pressure screen (4, 7) consists of a number of vanes (3).

3. Conical refiner according to claim 1 or 2, characterized in that, in the direction of the pulp flow, the pressure screen (4, 7) is placed essentially at the middle of the stator blade (2), so that it divides the refining zone (6) into two parts.

4. Conical refiner according to any one of claims 1-3, characterized in that, in the axial direction of the refiner, the cylindrical part of the rotor blade (1) is longer than the screen plate (4).

5. Conical refiner according to any one of claims 1-4, characterized in that the pulp rejected by the screen plate (4) passes through the second part of the refining zone to the delivery side (8) of the refiner and is removed via the exit connection (C).