EP3015178A1 - Method and device for moisture-dependent control of waste paper sorting assemblies - Google Patents

Abstract

The invention relates to the control of a paper sorting plant for the sorting of waste paper-cardboard mixtures, wherein a measurement of moisture in the region of the entry of the sorting in the sorting takes place and depending on the measured moisture control of operating parameters of one or more units of the sorting takes place.

Description

The invention relates to a method and a device for controlling the operation of waste paper sorting plants. The generic term "waste paper" refers here mixtures of waste paper and cardboard from private households or commercial enterprises.

The sorting of the waste paper-cardboard mixtures is necessary so that the waste paper can be utilized as raw material in the papermaking industry by the paper industry. The recycling rate of waste paper for this purpose is well above 70%. It can be observed that the relative proportion of cardboard in the wastepaper-cartonboard mixtures increases significantly, partly because of the decline in the amount of printed paper, in particular newspapers and magazines, due to the Internet but due to increasing internet purchases is increasing.

The basis of papermaking from waste paper is the deinking process, with which the printed ink is completely washed out of printed waste paper, so that the remaining paper fiber can be used to produce new paper. The waste paper fraction formed by printed paper such as newspapers, magazines and the like, which can be used after the deinking process to raw material for the production of new paper, is therefore also referred to as deinking material.

So that the processing of the waste paper can be carried out economically in the deinking process, it is important to obtain as pure a deinking material sorting product as possible by sorting the waste paper / paperboard mixtures. For this purpose, it is necessary, in addition to foreign substances or contaminants such as plastics to separate the cardboard as completely as possible from the deinking material fraction.

On the other hand, the sorting of waste paper-cardboard mixtures should be economical, which requires automatic sorting. These, in turn, should be used as well and consistently as possible in order to be able to work economically, which requires being able to drive the highest possible and consistent throughput, while at the same time being able to ensure the best possible quality of the deinking starting product.

Automatic sorting systems for sorting waste paper-cardboard mixtures are known. Usually, after the feed bunker, a coarse screen and a fine screen are used as input units in order to deposit large-area cardboard boxes by means of the coarse screens and to deposit foreign substances and small shreds of paper by means of the fine screens. Thereafter, the separation of small-area cardboard and deinking material by mechanical aggregates such as spikers spear and segregate the cardboard boxes with spikes, and optically controlled aggregates such as near-infrared scanner and camera systems that optically recognize the cardboard and optionally plastic parts and their ejection from the Cause material flow.

Examples of such known sorting systems, which work with optoelectronic systems for distinguishing paper and cardboard and to effect their separation, can be found in the EP 1 533 045 B1 , of the EP 0 873 797 A2 , or the EP 1 048 363 B1 ,

It is also known in such automatic sorting systems, for the purpose of maintaining a required quality of deinking material as sorting product to control the plant operation in a certain way. This is done by monitoring the deinking material discharge at the end of the sorting process. This can be done with a near-infrared scanner system or a camera system that recognizes residual cardboard left in the deinking material discharge. If a predetermined limit is exceeded Such residual cartonage is then throttled the speed of the plant to reduce their mass flow rate. Too high a proportion of cardboard in the deinking material discharge means that the speed and mass throughput of the plant are too high to effect a sufficiently complete separation of the cardboard. This is important because the proportion of cardboard in the waste paper / paperboard mixture can vary greatly depending on the origin of the waste paper product.

• Ein erster Nachteil besteht darin, dass der Steuereingriff aufgrund der Überwachung der Materialaustragsqualität am Ende der Sortieranlage erfolgt. Wenn beispielsweise die aus dem Aufgabebunker erfolgende Materialzufuhr sich in der Zusammensetzung ändert, weil die momentane Charge einen höheren Kartonagenanteil hat, kann das von der Anlage erst mit einer Verzögerung erfaßt werden, die der Durchlaufzeit des Materials durch die gesamte Anlage entspricht.

However, this known control method has two major disadvantages:

• A first disadvantage is that the control intervention takes place due to the monitoring of the material discharge quality at the end of the sorting system. For example, if the material feed from the feed bunker changes in composition because the current batch has a higher percentage of cardboard, this can only be detected by the equipment with a delay corresponding to the throughput time of the material throughout the equipment.

The second disadvantage is that the quality control by means of near-infrared scanner or a camera system detects only the surface quality, so the composition of the material flow reproduces on the surface, so that the validity of the detection is deficient.

Finally, this known system control is not optimal, because it can act only in terms of slowing down the system and thus reducing the mass flow rate on the system, and because a reduction in mass flow rate, of course, has a negative impact on the efficiency of the system.

However, it is also known to install combined near-infrared and camera systems immediately after the task from the task bunker in order to prevent poor quality development and to intervene immediately and immediately. This happens because the throughput is reduced immediately after detection of an unfavorable material composition with increased cardboard content. Consequences, however, are as described above. Even there, however, there is the disadvantage described above of insufficient informativeness of the detection taking place only on the surface. in addition comes the fact that just larger cardboard boxes tend to concentrate in the feed mixture on the surface, which falsifies the recognition results. Again, the control intervention causes only a slowdown of the system and / or a reduction in throughput and thus a deterioration of cost-effectiveness.

The object of the invention is therefore to provide an improved method and a device for carrying out this method in order to enable optimized control of an automatic sorting system.

The solution to this problem is according to claim 1 (independent method claim) and according to the independent device claim is that a detection of the moisture content of the waste paper-cardboard mixture takes place and a plant control in dependence on the determined moisture of the material to be sorted. In this case, the moisture content of the paper-paperboard mixture is already detected at the beginning of the sorting process, preferably in the feed bunker, so that changes occurring during operation of the moisture of the sorting goods coming from the feed bunker have no time delay on the control of the system.

The invention is based on the recognition that the moisture of the material to be sorted has a significant influence on the sorting behavior and that also has an insignificant effect on the quality of the sorting product. The moisture content of waste paper carton blends can vary greatly; the state of such mixtures ranges from completely dry to very wet. It depends on the seasons as well as on storage and transport conditions. Material stored in warehouses has less moisture, while outdoor stored material may be very humid due to humidity and may also be quite wet due to rain, for example when transported in open containers, or when the wind blows rain into partially opened collection containers.

The effect of moisture in the material to be sorted is both a change in weight, as paper and cardboard are naturally heavier due to moisture absorbed, as well as a large change in stiffness. The greater weight of wet paperboard packaging makes blistering with air nozzles on the near-infrared separator less reliable, and the loss of rigidity With moist cardboard packaging, these can be impaled and removed less easily by a spiker.

In conventional sorting systems, there is no control due to any sorting criteria. The only intervention, as described above, takes place in known systems by throttling the material throughput, if too high a proportion of cardboard in the deinking Materialaustrag signals an overload of the system. With the plant control system according to the invention due to the current moisture of the sorting material when entering the sorting process to the effect that not only the speed and thus the mass flow rate of the system is changed, but function-optimizing effect on the individual units of the system, the sorting result at largely constant throughput of Improved system and be kept at a high level, even if difficult to handle sorting material with high humidity passes through the plant.

According to the invention, the degree of moisture of the material to be sorted is already detected in or at the feed bin, ie before the material to be sorted enters the actual sorting plant. The recorded moisture content of the material to be sorted serves as the basis for automated adjustment of the aggregates of the sorting system to optimize the sorting quality without loss of sorting speed and avoiding disturbances in the operation of the plant. The moisture measurement can preferably be carried out by means of a microwave resonance method. Thus, a penetration depth of the measurement of about 5 cm can be achieved. For this purpose, for example, be arranged on the walls of the task bunker in several height positions sensors, so that the humidity measurements can be made at different locations, or it can be done immediately following the task bunker moisture measurements.

An advantage of an optimally working sorting system is a pre-screening of the feed material by using a coarse screen known per se in order to sort out large-area cardboard boxes. This pre-screening of the delivery material through a coarse screen is carried out before the sorting material is fed into the charging bunker, where the moisture measurement takes place. This already reduces the problem of moisture in the paper, because the main component in the material mixture, which draws more water, is usually the Cardboard. This usually has a much higher degree of moisture than printed waste paper. By pre-screening, the moisturizing value of the feed material can be shifted slightly downwards, for example from 18% to 14%, since large-sized, high moisture content cardboard boxes are then no longer present in the material mixture entering the actual sorting plant. Because this improves the average surface tension or rigidity of the sorted material, a mechanical separation is simplified. In addition, then after a Vorabsiebung the material supplied to the plant has a more uniform density and a smaller grain size, which favors the sorting quality of the system, since the system can be adjusted to the optimized material.

• Bei Sieben kann in Abhängigkeit von der Feuchte eine Geschwindigkeitsregulierung der Paddel oder Scheiben erfolgen. Weiter kann bei den Sieben eine feuchteabhängige Einstellung der Neigung erfolgen, damit die Verweilzeit der Kartonagen auf dem Sieb immer im wesentlichen gleich bleibt und eine gleichbleibende Ausbringung sichergestellt ist, also die Geschwindigkeit der Kartonage beim Siebdurchlauf im wesentlichen gleich bleibt, obwohl feuchte Kartonagen schwerer beweglich als trockene Kartonagen sind. Es kann damit eine sogenannte Teppichbildung auf den Sieben vermieden werden, die aus starker Überlagerung des Sortiergutes herrührt, insbesondere wenn sich größere Kartonagen unten befinden, was zu einer verminderten Siebwirkung und damit auch Siebleistung führen würde.

The control of the individual units of the sorting system as a function of the detected moisture content of the sorting material can be carried out in terms of functional optimization of the respective unit depending on its specific mode of operation and independently of the other units of the plant in the following manner:

• In screens, depending on the humidity, a speed control of the paddles or discs can be carried out. Further, with the sieves a moisture-dependent adjustment of the inclination can be made so that the residence time of the cardboard always remains substantially the same on the screen and a consistent output is ensured, so the speed of the cardboard during the sieve run remains substantially the same, although moist cardboard heavier than dry cardboard boxes are. It can thus be avoided so-called carpet formation on the screens, which results from strong superimposition of the sorting material, especially when larger cardboard boxes are at the bottom, which would lead to a reduced screening effect and thus screen performance.

In air separators, for example, the blowing pressure and / or the suction pressure for sucking airworthy paper can be adjusted according to the humidity, in order to take into account the higher weight of wet paper.

In the case of the near-infrared separator, the blow-off pressure can be changed as a function of the humidity, so that the higher the humidity, the higher the blow-off pressure, so that heavier cardboard boxes with uniform parabola parallels are discharged due to the moisture content can. The Ausblasimpulsdauer can be adapted to the humidity, so that it is slightly longer at higher humidity.

With the Spiker, the velocities of the drum and the accelerator belt leading to the Spiker can be reduced slightly at higher humidity, so that there is less vibration and struck cardboard can not detach from the spike due to vibration.

In addition, an apex adjustment can be made vertically and / or horizontally on the near-infrared separator to help keep the ejection parabola of the differently heavy and differently stiff material depending on the degree of moisture substantially constant and thus maintain the quality of separation.

If the prescreening described above is used, the homogeneity of the material mixture entering the feed bunker is improved because of the pre-separation of large cardboard boxes, thereby making the moisture measurement more accurate; This means that the measured values recorded by the individual sensors correspond more exactly to the average moisture content of the sorted material.

Vorabsiebung also has the advantage that disturbances of the sorting system are avoided by congestion, as they occur again and again when a screening of large cardboard boxes only after abandonment of the material mixture from the hopper on the actual sorting, especially the danger of congestion with increasing humidity of the Material and thus decreasing stiffness of cardboard packaging increases significantly.

An embodiment of the invention is sketched in the accompanying drawings only very schematically and will be explained briefly in the following.

The drawing shows in the form of a block diagram a waste paper sorting system with a controller according to the invention by integrated humidity measurement.

A task bunker 1 conveys the material mixture to be sorted to the actual sorting system, which has a conventional sequence of units in the embodiment.

Upstream of the feed bunker 1 is a pre-screening unit 2, which sifts large-area cardboard from the feed material, so that the remaining paper-cardboard waste mixture no longer contains large-area cardboard. The material passing from this presoiling unit 2 into the receiving bunker 1 is therefore more homogeneous in terms of particle size and has a more uniform moisture content, after the cardboard material known to be particularly moisture-wicking has been deposited in the area of the large-area cardboard.

Downstream of the task bunker 1 is the actual sorting system, which may comprise several units, of which only a few are shown here by way of example. Thus, in the schematic representation of the drawing, a sieve unit 3, a near-infrared separator unit 4 and a spike unit 5 are shown. At the end of the system is a collecting container 6, which collects the deinking material as a sorting product.

The sequence of units shown in the drawing is only an example. There may be more or less aggregates, and the order may vary. In the embodiment, a near-infrared separator 4 is shown in front of a Spiker unit 5, this order can also be reversed. Instead of a sieve unit 3, several sieve units of different sieve size can be connected in series. The arranged between the units transport sections are indicated only by connecting lines.

In particular, it should be borne in mind that the invention relates neither to the specific units used, nor to the number of units, nor to the order of aggregates in the course of the sorting system, but rather to the humidity-dependent control of the units to optimize their operation ,

The measurement of the moisture is preferably carried out in the feed hopper 1, on whose inner wall a plurality of sensors 7 are distributed both on the circumference and in different height positions can be arranged. Alternatively (not shown), the moisture measurement can also take place at the discharge directly behind the hopper 1.

A controller 8 controls the system as a function of the humidity measured by the sensors 7 of the sorted material. Via output lines 9, the individual units and possibly also the intermediate transport areas are controlled in the manner described above to optimally adjust their operation or function depending on the moisture content of the material to be sorted, so that an optimal sorting results with the greatest possible system throughput. The is shown by indicated control lines 9 from the controller 8 to the units and the intervening transport units (belts).

Claims (15)

A method for controlling a waste paper sorting plant for sorting mixtures consisting essentially of waste paper and cardboard, wherein the degree of moisture of the sorted material in the region of its entry into the sorting plant is detected by measurement, and wherein depending on the measured moisture content of the sorted material at least one Operating parameters of at least one of the aggregates of the sorting system is set. The method of claim 1, wherein the operating parameters of a plurality of aggregates of the sorting system are set in dependence on the measured moisture content of the sorting. A method according to claim 1 or 2, wherein prior to the measuring point of the moisture content of the sorting a pre-screening of larger cardboard from the mixture. Method according to one of claims 1 to 3, wherein the measurement of the degree of moisture of the sorted goods in a task bunker (1), from which the sorted material is fed to the aggregates of the sorting system. Method according to claim 4, wherein the measurement of the degree of moisture of the sorting material takes place at several points of the circumference and / or at several height positions of the feed bunker (1). Method according to one of claims 1 to 5, wherein depending on the measured moisture level of the sorting material, the inclination and / or the opening width of Siebaggregaten is controlled. Method according to one of claims 1 to 5, wherein, depending on the measured moisture level of the sorting material, blow-out pressure and / or blow-pulse duration and / or the suction pressure of air classifiers, near infrared separation units or similar units are controlled. Method according to one of claims 1 to 5, wherein depending on the measured moisture level of the sorting belt speeds of transport sections of the sorting system and / or operating speeds of Spikeraggregaten be controlled. Method according to one of claims 1 to 5, wherein depending on the measured moisture content of the sorting material, the horizontal and / or vertical separating vertex position of near-infrared separating units or similar ejection units is controlled. Device for carrying out the method according to one of claims 1 to 9, having one or more sensors (7) for detecting the degree of moisture in the sorting material, further comprising a controller (8) which receives moisture measurement signals from the or each sensor (7) and in dependence thereof generates control signals for controlling at least one operating parameter of at least one unit (3, 4, 5) of the sorting system. Device according to claim 1, wherein the screening plant is preceded by a preliminary screening unit (1) for separating larger cardboard boxes. Device according to claim 10 or 11, wherein the sorting system comprises one or more screening units (3) which is or are controllable by the regulator with respect to screen pitch and / or screening speed. Device according to claim 10 or 11, wherein the sorting system comprises a near-infrared separator unit, which controllable by means of the regulator with respect to horizontal and / or vertical separating vertex adjustment, blow-off pressure and / or Ausblasimpulsdauer is. Device according to claim 10 or 11, wherein the sorting system comprises a spike unit (5) whose operation is controllable by the controller (8). Device according to claim 10 or 11, wherein the sorting system has at least one transport section whose speed and / or another parameter can be controlled by the controller (8).

Images