AT516657A2 - TRANSPARENCY FEEDING SYSTEM FOR A FIBERGLAVE MACHINE AND METHOD FOR SUPPLYING A SUPPLY WATER TO A MULTILAYER RUNNING OF A FIBERATOR WEAVING MACHINE - Google Patents

Abstract

There is provided a headbox feeding system for a fibrous web machine, comprising fiber adding means (3) for adding fibers to a feed water, additive adding means (5) for adding an additive to the feed water, a mixing means (6) disposed downstream of the fiber adding means and the additive adding means in order to mix the fibers and the additive in the feed water and from which the resulting mixture is fed to a multilayer headbox and a recirculation means (10). The recirculation means (10) is configured to recycle a portion of the mixture from a location upstream of the multi-layer casserole to a location upstream of the additive adding device (5) into the feed water.

Description

TRANSPARENCY FEEDING SYSTEM FOR A FIBERGLAVE MACHINE AND METHOD FOR SUPPLYING A SUPPLY WATER TO A MULTILAYER RUNNING OF A FIBERATOR WEAVING MACHINE

The present invention relates to a headbox feed system for a fibrous web machine and to a method for feeding a feed water to a multi-layer headbox of a fibrous web machine.

From EP 2 784 214 A1, for example, a headbox feeding system for a fibrous web machine is known. In this headbox feed system, refined fibers and an additive in the form of cationic starch are added to a feed water and mixed by means of a pump. Colloidal silica is then added downstream of the pump and the resulting mixture is fed to an intermediate layer of a multi-layer cake to form an aqueous, middle layer. This design allows for identification of the addition time of the additive, which allows the pulp web properties to be better controlled. For cost reasons, it is desirable to keep the use of materials, in particular the use of the additive, as low as possible, while at the same time a sufficient quality of the fibrous web produced is to be ensured.

Therefore, it is the object of the present invention to provide a headbox feed system for a fibrous web machine and a method for feeding a feed water to a multi-layer headbox of a fibrous web machine, with which the material usage can be reduced while ensuring sufficient quality of a manufactured fibrous web.

The object of the invention is achieved with a headbox feed system according to claim 1 and a method for feeding a feed water to a multi-layer headbox of a fibrous web machine according to claim 9. Advantageous developments of the invention are the subject of the dependent claims.

The headbox feeding system of the present invention for a fibrous web machine (for example, a paper or board machine) has a fiber adding means for adding fibers to a feed water, additive adding means for adding an additive (which preferably serves to increase the adhesion between the fibers) into the feed water mixing means disposed downstream of the fiber adding means and the additive adding means and configured to mix the fibers and the additive in the feed water and from which the resultant mixture is supplied to a multi-layer bake, and a recirculation means. In this case, the recirculation device is designed to return a portion of the mixture from a point upstream of the multilayer headbox to a point upstream of the additive addition device into the feed water.

The fact that a portion of the resulting mixture is returned to the supply water before reaching the Mehrlagenstoffauflaufs, at a location upstream of the additive addition means, the consumption of the additive and the added fibers can be reduced, while at the same time a sufficient quality of the fibrous web produced is ensured. As a result, natural resources such as wood or waste paper, etc. can be saved and the manufacturing cost can be reduced as a whole.

There is also included an arrangement in which at least one recycle conduit branches off upstream of a water distributor upstream of the multilayer headbox and / or at least one recirculation conduit downstream of the water manifold branches off (preferably from a line that leads from the water distributor to a machine chest).

The feed water is preferably white water, which may be mixed with pulp. However, the feed water may also be fresh water or service water or contaminated water, which may be mixed with pulp.

Preferably, the additive adding means is located downstream of the fiber adding means and the recycling means returns the mixture to the feed water at a location between the fiber adding means and the additive adding means. With this arrangement, i. the return between the fiber adding device and additive device, a high quality of the produced fibrous web can be achieved.

Preferably, the feedback device has a control valve, with which the proportion of the recirculated mixture can be adjusted.

As a result, it is possible in a simple manner to set the optimum return portion or to adapt the return portion optimally to the respective operating situation.

Preferably, the control valve is set to recirculate approximately 5 to 20% of the mixture with respect to a total flow (i.e., a flow rate of the mixture at the downstream branch point of the recirculation device). This allows a very good balance between the reduction in material usage and sufficient quality of the fibrous web produced.

Preferably, the headbox feed system is further provided with an auxiliary addition means located downstream of the fiber adding means and upstream of the additive adding means for adding a filler and / or a chemical to the feed water. Preferably, the chemical is a retention chemical, such as colloidal silica. It is also possible as a chemical, for example, to add starch (for example cationic starch) by means of the additional addition device.

Preferably, the recirculation means returns the mixture to the feed water at a location between the supplemental addition means and the additive addition means. Alternatively, the recirculation means may recirculate the mixture into the feed water via a manifold connected to the supplemental addition device along with the filler and / or chemical to be added. As a result, the recycled mixture with the filler and / or the chemical can already be premixed, so that overall improved mixing is achieved, which in turn increases the quality of the fibrous web to be produced.

Preferably, the additive is starch. This leads to a high adhesion / bonding between the fibers. In particular, cationic starch is preferred, which has a very high binding capacity.

Preferably, the fibers are refined fibers and / or nanofibers. Refined fibers include, for example, recycled fibers or chopped wood pulp, which fibers have been refined by means of a refiner which modifies fiber properties. The typical fiber length of refined fibers ranges from several hundred microns to two to three millimeters (depending on the fiber length of the original wood material and the recycling rate). Nanofibers are significantly smaller than the refined fibers, for example, the fiber width is in the nanometer range and the fiber length is usually in the range of a few micrometers. By using nanofibers, the quality of the fibrous web produced can be further improved.

Preferably, the multi-layer headbox contains three superimposed layers, wherein the headbox feed system supplies the resulting mixture to the middle layer of the multi-layer headbox. The other two plies of the multi-ply bake are connected to a pulp feed system which feeds pulp to these two plies. Thus, according to the invention, not customary stock is fed to the middle layer of the multicompartment casserole, but a mixture of feed water, fibers and additive (and optionally an additive). As a result, a fibrous web of sufficient quality can be inexpensively manufactured.

The invention also relates to a method for feeding a feed water to a multi-layer casserole of a fibrous web machine (preferably a paper or board machine) comprising the steps of adding fibers to the feed water, adding an additive to the feed water, mixing the fibers and the additive in the feed water at a location downstream of the fiber feed point and the additive addition point and feeding the resulting mixture to the multilayer headbox, and returning a portion of the mixture from a location upstream of the multi-layer headbox to a location upstream of the additive addition point into the feed water.

Preferably, the additive addition occurs downstream of the fiber addition and the mixture is recycled to the feed water at a location between the fiber addition point and the additive addition point.

Preferably, about 5 to 20% of the mixture is recycled with respect to a total flow (of the mixture).

Preferably, the method further comprises the step of adding a filler and / or a chemical, which is preferably a retention chemical such as colloidal silica, to the feed water at a location downstream of the fiber feed point and upstream of the additive feed point.

The mixture is preferably recycled to the feed water at a point between the additional addition point and the additive addition point. Alternatively, the mixture may first be premixed with the filler and / or chemical to be added and then returned to the feed water.

Preferably, the additive is starch, preferably cationic starch.

More preferably, the fibers are refined fibers and / or nanofibers.

The multi-layer headbox preferably contains three layers arranged one above the other and the resulting mixture is fed to the middle layer of the multi-media headbox, wherein fibrous pulp is fed to the other two layers of the multi-headbox.

The same advantages and effects obtainable in connection with the headbox system mentioned above are also obtainable by the above-mentioned method. Also, the explanations relating to the above-mentioned headbox system apply equally to the above-mentioned method.

Hereinafter, a preferred embodiment of the invention with reference to the accompanying Figure 1 is explained.

FIG. 1 schematically illustrates a headbox feed system for a fibrous web machine according to the preferred embodiment of the present invention.

Referring to Fig. 1, the headbox feeding system for a fibrous web machine (e.g., a paper board machine) according to the preferred embodiment has a water supply means 1 for supplying feed water, which is white water in this embodiment, into a machine chest 2. Starting from the machine chest 2, the feed water, optionally mixed with pulp, via a line 9a to a mixing device 6, here in the form of a feed pump supplied. A fiber adding device 3, an auxiliary adding device 4 and an additive adding device 5 are provided in this order in the direction from the upstream end of the pipe 9a to the downstream end of the pipe 9a. The fiber adding device 3 in this embodiment gives refined fibers or nanofibers to the one located in the pipe 9a

Feed water too. The additive addition device 4 in this embodiment adds colloidal silica as a retention chemical to the feed water. The additive adding device 5 in this example adds cationic starch to the feed water.

The fibers, the colloidal silica and the cationic starch are mixed by the mixer 6 in the feed water, and the resultant mixture is supplied via a pipe 9b to a filter 7 which removes foreign matters (such as impurities, plastic particles, metal grains, etc.) from the water resulting mixture removed.

Subsequently, the mixture is supplied via a line 9c to a water and mixture distributor 8, and from there to a middle layer of a three-layer Mehrstoffauflaufs (not shown). Pulp pulp is supplied to the other two layers of the multi-fuel casserole.

Furthermore, the exemplary embodiment according to the invention has a return device in the form of a return line 10 and a control valve, not shown. The recycle line 10 branches off from a location between the mixer 6 and the multilayer headbox (upstream of the water and mixture manifold 8) and directs a portion of the resulting mixture to a location upstream of the additive addition device 5, i. the additive addition point, back. In the present embodiment, the return line 10 terminates in a manifold connected to the supplemental feed device 4, through which the recycled portion of the mixture is returned together with the chemical to be added to the supply water present in the line 9a (ie, the recycled portion of the mixture is mixed with the feed line) Chemical premixed and then added to the feed water). By means of the control valve while the proportion of the recirculated mixture can be adjusted. In this embodiment, the control valve is set such that approximately 5 to 20% of the mixture is recirculated with respect to a total flow (i.e., a flow rate of the mixture at the downstream branch point of the recycle line 6).

Further, the headbox feed system is provided with a second return line 11 which returns excess feed water from the water and mixture manifold 8 to the machine chest 2.

As described above, in this embodiment, the return line 10 is provided, which from a point between mixing device 6 and water and mixture distributor 8, d. H. upstream of the water and mixture manifold 8, and returns a portion of the resulting mixture to a location upstream of the additive addition device 5. Additionally or alternatively, a recirculation line may be provided which branches off downstream of the water and mixture distributor 8, preferably from the line 11, and returns a portion of the resulting mixture to a location upstream of the additive addition device 5.

With the headbox feeding system according to the present embodiment, by recycling the resulting mixture, the material input can be reduced while ensuring sufficient quality of the fibrous web. This will be shown below by means of two examples. The quality of the fibrous web is evaluated on the basis of the achieved strength of the fibrous web.

First example

In the first example, nanofibers and cationic starch are added by the fiber addition device 3 and the additive addition device 5 in white water (no additional addition). Without recirculation and with the addition of 0.5% / 1.0% / 1.5% nanofibers and 8 kg / t cationic starch, a fibrous web with a [Fluygen] strength of 350 to 500 J / m2 can be achieved. With recycle (ie a return of 5 to 20% of the mixture with respect to a total flow), with the addition of 0.5% / 1.0% / 1.5% nanofibers, as well as only 6 kg / t of cationic starch, a fibrous web can be formed with one [Fluygen] strength of 350 to 550 J / m2 can be achieved.

Second example

In the second example, refined fibers, colloidal silica and cationic starch are added through the fiber feeder 3, the additive feeder 4 and the additive feeder 5 in white water, respectively. Without recirculation and with the addition of 5% refined fibers, 300 g / t colloidal silica and 8 kg / t starch, a fibrous web with a [fluid] strength of 250 to 290 J / m2 can be achieved. With feedback (5 to 20% feedback), the same strength range, i. [Fluygen] strength of 250 to 290 J / m 2, with addition of 5% refined fibers, 300 g / t of colloidal silica, and only 6 kg / t of starch.

Consequently, it is possible with the headbox feed system according to the invention (as well as the method according to the invention) to reduce the use of material and at the same time to ensure or improve the quality of the fibrous web produced.

Claims (15)

A headbox feeding system for a fibrous web machine, comprising: fiber adding means (3) for adding fibers to a feed water, additive adding means (5) for adding an additive to the feed water, a mixing means disposed downstream of the fiber adding means (3) and the additive adding means (5) (6) configured to mix the fibers and the additive in the feed water and from which the resulting mixture is fed to a multi-layer bake, and recycle means (10) configured to recover a portion of the mixture of a point upstream of the Mehrlagenstoffauflaufs to a point upstream of the additive addition means (5) in the feed water due. The headbox feed system according to claim 1, wherein the additive adding means (5) is disposed downstream of the fiber adding means (3), and the recycling means (10) returns the mixture into the feed water at a position between the fiber adding means (3) and the additive adding means (5). 3. Headbox feed system according to claim 1 or 2, wherein the return means (10) comprises a control valve with which the proportion of the recirculated mixture can be adjusted. 4. Headbox feed system according to claim 3, wherein the control valve is set such that about 5 - 20% of the mixture are recycled with respect to a total flow. The headbox feed system according to any one of claims 1 to 4, further comprising additional feed means (4) disposed downstream of the fiber adding means (3) and upstream of the additive adding means (5) for adding a filler and / or a chemical, preferably a retention chemical such as colloidal silica is, in the feed water. 6. headbox feed system according to claim 5, wherein the recirculation means (10), the mixture at one point between the additional addition means (4) and the additive addition means (5) in the feed water, or the return means (10) the mixture via a with the additional addition means (4 ), together with the filler to be added and / or the chemical to be added back into the feed water. The headbox feed system according to any one of claims 1 to 6, wherein the additive is starch, preferably cationic starch, and / or the fibers are refined fibers and / or nanofibers. The headbox feed system of any one of claims 1 to 7, wherein the multi-layer headbox comprises three superimposed layers, and the headbox feed system supplies the resulting mixture to the center layer of the multi-layer headbox, and the other two layers of the multi-layer headbox are connected to a pulp feed system. A method of feeding a feed water to a multi-layer bunk of a fibrous web machine, comprising adding fibers to the feed water, adding an additive to the feed water, mixing the fibers and the additive in the feed water at a location downstream of the fiber feed point and the additive addition point and feed the resulting mixture to the headbox and returning a portion of the mixture from a location upstream of the headbox to a location upstream of the additive addition point into the feed water. The process of claim 9, wherein the addition of additive occurs downstream of the fiber addition and the mixture is recycled to the feed water at a location between the fiber addition point and the additive addition point. The process of claim 9 or 10, wherein about 5-20% of the mixture is recycled relative to a total flow. The method of any one of claims 9 to 11, further comprising the step of adding a filler and / or a chemical, which is preferably a retention chemical such as colloidal silica, into the feed water at a location downstream of the fiber feed point and upstream of the additive feed point. 13. The method of claim 12, wherein the mixture is recycled at a point between the additional addition point and the additive addition point in the feed water, or the mixture is first premixed with the added filler and / or the chemical to be added and then returned to the feed water. 14. The method according to any one of claims 9 to 13, wherein the additive is starch, preferably cationic starch, and / or the fibers are refined fibers and / or nanofibers. 15. The method according to any one of claims 9 to 14, wherein the multi-layer headbox contains three superimposed layers and the resulting mixture is fed to the middle layer of Mehrlagenstoffauflaufs, and pulp is fed to the other two layers of Mehrlagenstoffauflaufs pulp.