DE1217588B - Use of wood chippers - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

B 271

D 21b

German KL: 38 i - 4

Number: 1 217 588

File number: Z103961 c / 38 i

Filing date: October 5, 1963

Opening day: May 26, 1966

When using chips, chips, especially wood chips, in the wood processing Industry, it is necessary for many processing purposes that the wood is free from bark components because parts of the bark have a completely different structure and chemical composition than the wood desired for processing, so that, for example, when processing the schnitzel difficulties arise with chipboard or other pressed objects. In many cases the natural color of the bark is also undesirable. In addition, due to its porosity, the bark tends to increased absorption of binding agents. In addition, it is very soft and capable of this Reason not to give the finished products high stability.

The bark components are also undesirable in the pulp industry, as they are after the pulp boiling reduce the whiteness of the resulting pulp and greatly reduce the purity of the pulp affect.

In order to avoid these disadvantages in wood processing, one has so far been of it assumed that the wood should first be freed from the bark and then, for example using chopping machines, to shred. Debarking is done on a large scale by debarking machines. Through this there are additional costs and operations. In this measure, on the one hand Difficulty to overcome that in the peeling process with the bark not too much wood is lost. Provides On the other hand, the peeling is done so sparingly that part of the bark is still on the trunks remains adhered, the first-mentioned disadvantage is present again that after the comminution process the bark remains, if it is not sorted particularly well, on the chips or chippings.

It has now been found that it is possible to obtain bark-free chips from bark wood in a simple way to obtain. The invention consists in the use of known chopping machines with a a performance of at least 4001 m / sec. appropriate Impact force of the chopping knife on the wood for the production of barkless wood chips for the pulp digestion from wood still afflicted with the bark at a throughput Shredding of at least 1 cbm / min, preferably 2 cbm / min, based on 1 cbm of the chopping disk surrounding housing space minus the space required by the chopping disk.

Through a subsequent sorting, which is also carried out with known devices, Use of wood chippers

Applicant:
Waldhof pulp mill,

Mannheim-Waldhof, Sandhoferstr. 176

Named as inventor:

Franz Dorn, Kelheim;

Dr. Heinz Haas, Weinheim (a. D. Bergstrasse);

Dr. Otto Moldenhauer, Kreßbronn-Berg

can mostly be as dust and powder, but in any case in a significantly smaller size than the wood chips, resulting bark components, for example through a cyclone and through moving Sieve surfaces, e.g. B. vibrating sieves are separated. Previously common wood chippers less During normal operation, performance was provided by wood chips to which the bark still adheres relatively firmly. It was now surprising that more powerful chopping devices succeeded in attacking the bark To destroy the chips mechanically or in their structure by the comminution process to influence that they fall off easily from the wood components and are very strongly comminuted.

This occurs when the chopping knives hit the wood with a force equal to that of 400 t m / sec. is equivalent to. It has been shown when using this service that it is excellent Way the bark of z. B. beech wood is so much shredded that it is mechanically sorted can be separated from the wood chips so far that only a small residue remains in the Pulp sorting can be removed. However, it can also be used for other types of wood, such as Coniferous wood, the bark being removed. However, it has been found to be beneficial to the benefits to increase the devices, the more firmly the bark adheres to the wood.

Furthermore, to achieve the desired effect, it is necessary to direct the chopping process in such a way that that the chips formed when passing through the chopping disk immediately after the cutting process enter the adjoining cavity of the hacker in such an amount, that the schnitzel have enough opportunity to touch each other to avoid the damaged ones Loosen the bark even further

609 570/146

or repel. It has been found that at least 1, preferably 2 cbm of schnitzel per Cubic meters of space and minutes less chopping disk have to be pushed through. By the impact the shovel-like drivers on the back of the chopping disk, due to the rapid change of high pressure - caused by the cutting process - and subsequent sudden pressure reduction as well as the mutual influence of the schnitzel, the rind is practically complete separated and smashed and enters the downstream cyclone together with the cossettes, where preferably the dust particles are separated, and then on the sorters on which the coarser parts of the bark, which are much smaller than the wood chips, are sieved off.

The inventive use of the known wood chopping machine at the same time Debarking the cumbersome prior debarking on special devices is avoided. About that In addition, however, there is also a careful separation of bark and wood, which was previously the case with the known Peeling facilities could not be achieved. In addition, the bark falls dry and dusty so that it can be subjected to immediate further processing or use. This results in better utilization of the wood supplied. Another benefit comes in addition, with the appropriate choice of separation devices, such as cyclone and / or sorter, the dust-like pieces of bark adhering to the wooden parts are largely removed, so that the As a rule, bark particles that are quite firmly adhering to the wood do not wait until the pulp has been boiled must be removed. By using the wood chopping machine known per se according to the invention, One can be made of bark wood to which sorting devices are optionally connected downstream Produce pulp with a high purity and a high whiteness.

The invention will be described in more detail below using the example of the crushing and debarking of beech wood explained.

Beech wood in roll and billet form and an average bark content of 5 to 6%, the depends on the trunk thickness or the age of the wood, in the usual length of 1 m, becomes one Chopping machine supplied with four or more knives. The revolving chopping disk with knives Chops the wood after it has passed through the chipper jaw, depending on the setting of the chopping knife in wood chips with a thickness of 3 to 6 mm. For shattering or extensive loosening the bark adhering to the wood, the knife in question must be medium when it hits the wood Output of at least 4001 m / sec. exhibit. This is achieved in that the chopping disk with a correspondingly high number of revolutions works, at the same time the weight of the chopping disk is of crucial importance. Is the point of impact of the knife, for example has a length of 10 to 60 cm, far from the pivot point of the chopping disk, is sufficient according to the physical laws a slower rotation of the chopping disk to get the desired effect than if the point of impact is closer to the pivot point.

Compared to the movable chopping knife, the known chopping machines have a fixed one Knife, the so-called stick knife, attached, and behind or under the chopping knives has the Chopping disk has a through hole (channel). This construction determines the path that the Wood chips have to go through. After chopping off, the cutlets are cut through the stick knife prevented from dodging down. Rather, they are forced through the canal step through and thus get into the space of the chopping disk located behind the chopping disk surrounding housing. This cavity must be designed so that as a result of the driven Amount of chips and the air already present in them, an instantaneous compression occurs. The schnitzel meet on the way from the knives through the chopping disk into the housing space with great force both against the stick knife, against the inside of the chopping disk and against the ejection angle on the back of the chopping disk and the rear wall of the chopping hood. These bumps bring about a further loosening or shattering of the by the cleaver chipped or already chipped bark with it. In addition, there is also the fact that that by the vortex prevailing in the room the chips collide with each other and thereby repel the soft parts of the bark.

From the ejection angles on the back of the chopping disc and by means of the compressed air the wood chips are then thrown into a cyclone, which separates the chips from the dust particles that cause the consist largely of bark and fine sawdust. The further separation of coarser bark particles, which are not separated by the cyclone, can then in a known manner Sieve separators, e.g. B. shaking sieves, take place with appropriate hole sizes. The vast majority of the However, about 80 to 90% of the separated bark is in the separated bark after sorting Sawdust and can be used from there for other purposes, e.g. B. a combustion, are fed.

Claims (1)

Claim: Use of chopping machines known per se with an output of at least 400 t m / sec. corresponding impact force of the chopping knife on the wood for the production of Barkless wood chips for pulp digestion from imported chips that are still affected by the bark Wood with a throughput of chips of at least 1 cbm / min, preferably 2 cbm / min, based on 1 cbm of the housing space surrounding the chopping disk minus the Space requirement of the chopping disk. 609 570/146 5.66 © Bundesdruckerei Berlin