JPS62191590A - Method for refining fiber material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for refining fibrous material in an apparatus having a refiner. First of all, T.I.
Refining of the pulverized fiber material, such as pulverulent material, by VfP, CTMP, CMP or other processes for producing high-yield or so-called mechanical pulps is contemplated. More particularly, the invention relates to a combination of actions to reduce the energy consumption during refining of fiber materials, since the energy conversion is very high when using fibrous materials, and the amount of pulp per refining stage is 7 tons per refining stage. The hit is about t o o o K
This is because it has an energy conversion of the magnitude Wh, ie with a two-stage refining it has a total of approximately 2000 KWh per tonne produced.

Only a small portion of this amount of energy is used directly for the disintegration operation, whereas the major part of the amount of energy is consumed in transporting the moisture in the fiber material and optionally the liquid added to the steam. The steam produced in the milling space of the refiner would otherwise occupy an undesirable volume, since the steam at the pressure present in the milling space would make it more difficult for the fiber material to naturally pass through the milling space. This is because it reduces the retention time of the fibrous material in the milling zone.

For this reason, the main objective of the present invention is to reduce the energy conversion during the sofaning process by a combination of actions detailed below.

Even though there are multiple refiners with both grinding surfaces moving to achieve the desired relative movement in the grinding space, in the following example a fixed part called the stator and a rotor (rotating It only includes refiners that have adjacent movable parts called children.

The first energy-saving effect is to keep the rotating parts (rpm) primarily the same as before but significantly reduce the number of cutting elements in the rotor and stator, which significantly reduces the grinding frequency. I will let you do it.

A second energy-saving effect is to simultaneously increase the volume of the refiner, ie, increase the retention time of the fibrous material between the grinding members, to partially offset the reduction in grinding frequency. Since there is a limit on the diameter of the attrition zone due to the centrifugal force acting on the fiber material at the rotational speed when using a disc refiner with only a radially oriented attrition space, it is preferable to make the attrition space cylindrical. Alternatively, the volume of the grinding zone can be increased by a somewhat conical shape.

In this way, the diameter of the grinding zone can be kept within a suitable range while at the same time increasing the length of the grinding zone.

As a third energy-saving effect, the steam generated in the grinding space can be removed while the steam is still present in the grinding space, with the aim of lowering the energy consumption to also partially compensate for the reduction in the grinding frequency. This increases the ease with which the fibrous material is accessible to the refiner's grinding surface, thereby increasing the retention time during which the fibrous material remains in the grinding zone.

For this reason, much research and development research has been carried out regarding the shape design of the grinding member. are interchangeable. Canadian Patent No. 0/137 discloses that grooves (gr.
Examples of disc-shaped as well as cone-shaped grinding segments are shown having various shapes with respect to oove) or rods.

Alternative shapes for the disc and the seven eyener are described in U.S. Patent No. 3. The grooves of the smaller disk diameter are spaced apart by a relatively large distance, and the grooves are spaced apart from each other by a relatively large distance from the periphery of the disk. It is clearly seen that the distance becomes smaller and smaller. By milling frequency we mean the number of rotor revolutions per second multiplied by the number of structures on the periphery of the milling surface.

7 minutes/! A rotor rotation speed of 00 to 1000 rotations is considered normal, and this is Otsu000-200θOH2
gives the degree of the magnitude of.

By using the method of the present invention, the number of rotors and stakes of cutting members can be reduced from the usual 20 to 30 pieces while maintaining the plate speed of the rotor, and the degree of grinding can be approximately reduced. It has been found that if the frequency is lowered from 300 to 100 Hz, the energy consumption can be reduced considerably, and in advantageous cases by more than half.

It is necessary to increase the volume of the grinding space by making the grinding machine more or less circular, that is to say to increase the holding time between the grinding members. This allows the fiber material path through the refiner, i.e. along the conical surface, to be increased to a greater extent than was previously possible with disc refiners, since, as mentioned above, the diameter of the attrition zone can be made too large. This is because it is undesirable to increase it.

In order to further increase the retention time of the fibrous material in the refiner according to the invention, the generated steam is extracted continuously and primarily along the length of the rotor bore. This should result in as complete a separation of the steam as possible in order to reduce the compressibility of the chip-fiber-water-steam mixture, and this steam separation should contribute effectively to the direction of the applied shear force on the chips and fibers. do.

Effective extraction of steam from the grinding zone of a refiner has long been an industrial problem.

For example, Canadian Patent No. 107 as seven examples of steam extraction.
the law of nature! In addition to the grooves, the grinding element is provided with openings which suitably conduct the steam from the grinding space and the subsequent fibrous material to the back side of the grinding element. .

According to the invention, the steam generated in the milling space is largely entrained from the milling zone and, if necessary, is also cleanly extracted from the main part of the subsequent fiber material.

Steam is then entrained from the refiner through one or more steam outlets separate from the fiber material outlet. The amount of steam withdrawn is further regulated by maintaining a suitable pressure differential between the steam outlet and the fiber material outlet.

Claims (1)

[Scope of Claims] 1. A refiner having an inlet and an outlet for fibrous material, in which the fibrous material passes through a grinding space between grinding surfaces in which the fibrous material moves relative to each other. For example, in a method of refining a wet wood chip mixture or suspension to reduce its energy consumption, the following steps are carried out: (a) maintaining a normal rotational speed of approximately 1000 to 1500 rpm, typically approximately 400 to 600 rpm; By reducing the number of cutting elements to, for example, approximately 20 to 30, the degree of grinding of the fibrous material is usually reduced to approximately 6,000 to 20,000.
(b) making the grinding surface conical or cylindrical in order to allow a larger volume of the grinding space without reducing the diameter of the grinding member; (c) increasing the holding time of the fibrous material in the grinding space to offset the number of grindings lost due to a decrease in the grinding frequency; and (c) increasing the holding time of the fibrous material in the grinding space to In order to compensate for the number of millings lost due to a decrease in the milling frequency, a further step is provided in which the steam liberated by energy conversion from the liquid subsequent to the fibrous material is discharged continuously and radially from the milling space. A refining method for fiber materials characterized by combining. 2. The steam released from the grinding space is liberated in the refiner from mainly all the fibrous material following the steam, and the steam is extracted from the refiner through at least one steam outlet separate from the outlet for the fibrous material. 2. The method of claim 1, wherein the amount of steam released from the refiner is regulated by maintaining a suitable pressure difference between the steam outlet and the fiber material outlet.