RU2826706C1 - Method of mixing components of paper pulp during processing of waste paper and mixing unit for its implementation - Google Patents

Abstract

FIELD: processing of waste paper.

SUBSTANCE: group of inventions relates to processing of waste paper, namely to a method of mixing components of paper pulp when processing waste paper material and to a mixing unit for its implementation. Unit for mixing components of paper pulp during processing of waste paper material consists of a massive two-chamber mixing basin, into which a manifold and an intake branch pipe of the pump are embedded, wherein in each of the chambers a mixing device is supplied, made with possibility of being driven by an electric motor through a drive belt and a reduction gear or a conical gear reducer, directly connected to the rotor shaft, the intake branch pipe is connected to the headbox through the pump and supplies, at that, the manifold branch pipe and the pump intake branch pipe are embedded into the mass basin at angle of 45° in different directions, and each of them is installed on different sides of the partition, which is installed in the centre of the pool parallel to the walls of the chambers for a length extending beyond those edges of the chambers, into which the mixing devices are connected.

EFFECT: reduced risk of manifold clogging, increased time and intensity of primary mixing of flows, provision of stabilized direction of circulation of mass flow, avoiding risk of incompletely homogenised mass flow entering into headbox.

10 cl, 3 dwg, 8 tbl

Description

The solution relates to mass mixing units used in waste paper processing to improve flow homogeneity and to stabilize the direction of mass flow circulation.

Based on the findings of environmentalists, the issue of recycling waste paper must be approached comprehensively: from the beginning to the end of the cyclical process of obtaining and processing secondary raw materials.

The latest developments in the field of recycling paper raw materials allow it to be used as a semi-finished product in the manufacture of products of any quality, while more modern technological equipment and various chemical additives are used for production.

There are also specific features of using secondary raw materials, since the heterogeneity of the resulting mass does not guarantee the quality of the product. New methods of paper production developed by specialists are mainly based on the use of waste paper as the main component. The issues of the degree of processing, cleaning and mixing of waste paper mass are considered.

At the initial stage, it is necessary to comprehensively study many aspects of combined production. They should concern both the qualitative composition of secondary raw materials and their ability to interact with natural materials.

The fibers of waste paper recycled materials - secondary fibers - differ greatly in quality and structure from the fibers of natural raw materials - primary fibers, cellulose.

When subjected to various types of processing, the fibers lose their structure and integrity, which ultimately leads to the inability of the fibrous mass to absorb water, limits the ability to participate in chemical processes, and, consequently, worsens the quality of fibers obtained from secondary fiber. All this affects the appearance and quality of the final paper product.

The properties of paper and cardboard are largely determined by the fibrous semi-finished products.

For the structural elements of corrugated cardboard - paper for corrugating (fluting) and cardboard for flat layers of corrugated cardboard (liner), as well as for printing cardboard - high demands are placed on their mechanical properties.

First of all, they must combine sufficient strength and rigidity. When producing these elements from primary fiber - kraft cellulose and semi-cellulose - the mechanical strength indicators meet the requirements of the highest grades, both of the structural elements themselves and of the manufactured corrugated cardboard and box containers.

An alternative fibrous semi-finished product for the production of fluting and liner (test liner) is the mass obtained from waste paper - secondary fiber.

Waste paper pulp, being a derivative product from the processing of primary fiber, is inferior to the paper-forming properties of primary fiber. In connection with the task of increasing the strength of packaging paper and cardboard from waste paper, scientific work is constantly being conducted to find effective but cheap fibrous semi-finished products that would solve this problem in a composition with secondary fiber. Such fibrous semi-finished products are various types of wood pulp (WP). Thermomechanical pulp (TMP) and chemical-thermomechanical pulp (CTMP) turned out to be especially suitable.

To achieve the required quality indicators, waste paper raw materials are mixed with a flow of TMM wood fiber.

The method of mixing individual components of paper pulp must be selected taking into account the type of final product being produced, the total number and composition of the components and the method of preparing the pulp.

In the cyclic grinding method, mixing of properly prepared components is carried out in a mixing pool (see, for example: http://ros-printing.ru/articles/articles_2444.html).

The required amount of each component is fed into this pool. This amount can be determined using a float and a measuring rod. A specified amount of fillers, adhesives and most of the dyes are fed from measuring tanks into the same pool.

After mixing, some more dyes are added to the mass to obtain the exact shade. After that, the required amount of alumina is added and the finished mass is pumped into the machine pool. Usually, before this pool, the mass is passed through a mill to even out the grinding.

The above-described method of mixing all components in one mixing basin allows maintaining the ratio of individual fibrous components in the finished mass in a given proportion, while at the same time preventing different shades in the paper. This method is best suited for the production of colored high-quality papers produced in small quantities, with frequent changes in the assortment.

In the case of using a continuous milling method for the production of colored papers that do not allow for variations in shades, the components are mixed in two alternately used basins (see http://ros-printing.ru/articles/articles_2444.html for a diagram for two basins, as well as a diagram for two basins described in https://msd.com.ua/razmol-bumazhnoj-massy/smeshenie-voloknistyx-i-nevoloknistyx-komponentov-bumazhnoj-massy/ , published: 26.03.2015).

Pulp is continuously fed in a precisely specified quantity into the first pool. As soon as the cellulose in the pool reaches a certain level, its feed is switched to the second pool, and the corresponding amount of wood pulp is poured into the first pool from the reserve pool. Then fillers, sizing agents and dyes are introduced into this pool. The entire contents of the pool are mixed. Then the required amount of alumina is introduced. The prepared mass is pumped into the machine pool. As soon as the cellulose in the second pool reaches a specified level, its feed is again switched to the first pool, in which the entire mixing process is repeated. If such a scheme for preparing paper pulp involves two or more fibrous components, the grinding of which is carried out in a continuous manner, it is necessary to maintain the specified ratio of these components by feeding them through a composition regulator (quantity regulator). The described scheme for preparing paper pulp allows obtaining good results during reconstruction and modernization of paper pulp preparation departments for small and medium-capacity paper machines, the production program of which provides for the production of colored papers that do not allow for different shades, with frequent changes in the specified range of manufactured products.

In the production of mass types of paper on high-performance paper machines producing one type of paper, a complete continuous process of mixing all components of the paper pulp is used, which is controlled by the most modern control devices and regulating devices. One of the schemes of such a continuous process is given at (https://msd.com.ua/razmol-bumazhnoj-massy/smeshenie-voloknistyx-i-nevoloknistyx-komponentov-bumazhnoj-massy/ , published: 26.03.2015).

Individual fibrous components, fillers, etc., are fed to the composition regulator in a final prepared and liquid form with a precisely adjusted concentration. In the composition regulator, the precise dosing of fibrous components in a given ratio is carried out, just like the dosing of all other components of the paper pulp. Measuring flow meters, control valves for dosing fibrous components and special dosing pumps for fillers, adhesive emulsions and dyes are widely used.

The components, adjusted in the specified ratios, enter the sectional mixer.

The control of each section is linked to the established ratio and to maintaining a constant mass level in the mixing basin. From the mixing basin, the finished mass enters a special quantity regulator, the action of which depends on the speed of the paper machine.

The machine rejects from the collecting basin also go to the section mixer. However, the machine rejects dispenser is not connected to the dispensers of other fibrous materials, but is controlled by a special sensor directly connected to the finished mass quantity regulator. Such a device allows to avoid malfunctions that occur due to excess or shortage of ground rejects.

The described scheme for dosing and mixing the components of paper pulp operates completely automatically and allows continuous regulation of the ratio between individual components, however, as a rule, only within a limited range.

From Vanchakov M.V., Kuleshov A.V., Konovalova G.N. Technology and equipment for waste paper processing: a tutorial. - 2nd ed., corrected. and add. - SPbGTURP. SPb., 2011. 4.1. - 99 p. (see https://nizrp.narod.ru/texnoborudpererabmakul1_.pdf) it is known that waste paper arriving at the enterprise is subjected to dry grinding in hammer mills to fragments ranging in size from 1 to 5 cm. The crushed waste paper, which is a mechanical mixture of particles of fibrous and polymeric materials, is fed to sieves, where streams of individual components are separated from this mixture. Such separation is possible on conveyor or stationary vibrating sieves, through the cells of which the fibrous component and small heavy contaminants are sifted, and the film goes into a storage tank for subsequent disposal.

The fibrous component, containing the remains of small polymer particles and heavy contaminants, undergoes aero-separation and is additionally purified. The paper component, purified in this way from polymers, is fed into a mixer for mixing with water, additional dissolution and further processing in an aqueous medium, in accordance with the requirements of the production technology.

But the technology of mixing and the mixer device are not described in this literature.

The closest solution can be taken to be "EQUIPMENT FOR PULP AND PAPER PRODUCTION" in two volumes Volume 1. Equipment for the production of fibrous semi-finished products EDITED by the State Prize laureate V. A. CHICHAYEV, Moscow, Lesnaya Promyshlennost Publishing House 1981 - further [1], where on pp. 327-328 the pulp mixers are noted and there are schematic drawings of the inlet pipes located at right angles.

In general, [1] describes the process of mixing the components of paper pulp during the processing of waste paper raw materials, in which a two-chamber mass mixing pool is used, in which the mixing of masses fed through a collector is carried out, and the mixing is carried out in a closed cycle inside the pool using mixing devices located in each chamber and driven into rotation by an electric motor through a drive belt and a gearbox or a bevel gearbox directly connected to the rotor shaft, and the mixed masses are taken from the pool using a suction pipe, through which they are directed into a pressure box using a pump.

The disadvantages of using this design and other known mixer technologies described above when organizing the mixing of the mass flow with the waste paper flow (mass flow from primary fiber) is the short time for mixing the waste paper, as a result of which the non-homogenized mass flow enters directly into the machine pool and then into the pressure box, immediately entering the mass flow and partially entering the pressure box.

The result of the influx of non-uniform mass is low quality of the web

cardboard, the formation of “waves” and, as a consequence, a drop in the strength characteristics of the final product.

The objective of the invention is to eliminate the above-mentioned disadvantages.

The technical result of the claimed solution is:

- reducing the risk of collector clogging,

- increasing the time and intensity of primary mixing of flows,

- ensuring a stabilized direction of circulation of the mass flow,

- avoiding the risk of an incompletely homogenized mass flow entering the headbox.

The specified technical result is achieved due to the fact that a method is claimed for mixing paper pulp components during the processing of waste paper raw materials, in which a two-chamber mass mixing pool is used, in which the mixing of masses fed through a collector is carried out, wherein the mixing is carried out in a closed cycle inside the pool using mixing devices located in each chamber and driven into rotation by an electric motor through a drive belt and a reducer or a bevel gear reducer directly connected to the rotor shaft, and the mixed masses are selected from the pool using an intake pipe, through which they are directed into a pressure box using a pump, characterized in that the collector pipe and the pump intake pipe are cut into the mass pool at an angle of 45° in different directions, while each of them is located on different sides of the partition, which is placed in the center of the pool parallel to the walls of the chambers and extends along the length further than those edges of the chambers to which the mixing devices are connected.

Preferably, the partition is placed on the top of a wedge-shaped protrusion with a slope of 45°, the wedge of which is oriented inside the pool, and the pump intake pipe is inserted through the inclined surface of the wedge-shaped protrusion.

Preferably, the pool chambers are formed by two partitions, which are placed in the middle part of the pool so that an inter-chamber zone is formed between the partitions.

Preferably, the manifold is made to contain mass and chemical feeds that are inserted perpendicular to the manifold axis.

Preferably, a mesh filter is installed at the end of the pump intake pipe.

Also claimed is a unit for mixing components of paper pulp during processing of waste paper raw materials, consisting of a two-chamber mass mixing basin, into which a collector and a pump intake pipe are cut in, wherein a mixing device is supplied to each of the chambers, made with the possibility of being driven into rotation by an electric motor via a drive belt and a gear reducer or a bevel gear reducer directly connected to the rotor shaft, the intake pipe is connected to a pressure box via a pump and inlets, characterized in that the collector pipe and the pump intake pipe are cut into the mass basin at an angle of 45° in different directions, and each of them is installed on different sides of a partition, which is installed in the center of the basin parallel to the walls of the chambers for a length extending beyond those edges of the chambers to which the mixing devices are supplied.

Preferably, the partition is installed on the top of a wedge-shaped protrusion with a slope of 45°, the wedge of which is oriented towards the inside of the pool, and the suction pipe of the pump is introduced through the inclined surface of the wedge-shaped protrusion.

Preferably, the chambers of the pool are formed by two partitions, which are placed in the middle part of the pool so that an inter-chamber zone is formed between the partitions.

Preferably, the manifold comprises mass and chemical feeds cut into it perpendicular to its axis.

Preferably, a mesh filter is installed at the end of the pump intake pipe.

Brief description of the drawings

Fig. 1 shows the structure of the mass mixing unit (top view).

Fig. 2 shows the structure of the mass mixing unit (view in volume).

Fig. 3 shows the structure of the mass mixing unit (projections and sections from Fig. 1).

In the drawings: 1 - mixer, 2 - mixing chamber, 3 - interchamber partitions, 4 - interchamber zone, 5 - mixing device, 6 - stock pump, 7 - valve, 8 - pump intake pipe, 9 - manifold outlet, 10 - manifold, 11, 12 - reject inlets, 13 - TMM, 14 - long-fiber fraction (LFF), 15 - short-fiber fraction (SFF), 16 - dye, 17, 18 - chemicals, 19 - partition, 20 - drive belt, 21 - electric motor, 22 - electric motor shaft, 23 - stock basin, 24 - blade propeller, 25 - blades, 26 - pump intake pipe filter, 27 - wedge-shaped protrusion, 28 - mixing device axis, α - the angle of entry of the branch pipe and the angle of entry of the pump intake pipe; the arrows indicate the direction of movement of the mixing masses.

Implementation of the invention

Mixing of the components of the paper pulp during processing of waste paper raw materials occurs using a two-chamber mass mixing pool 1 (see Fig. 1-Fig. 3). In pool 23 of the mixer 1, mixing of the masses fed through the collector 10 is carried out. Mixing is carried out in a closed cycle inside the pool 23 using mixing devices 5 located in each chamber 2 and driven into rotation by an electric motor 21 through a drive belt 20 and a shaft reducer 22 or a bevel gear reducer (not shown), directly connected to the shaft 22 of the rotor of the electric motor 21.

The mixed masses are collected from pool 23 using intake pipe 8, through which they are directed into the pressure box using pump 6.

The unit for mixing the components of paper pulp during processing of waste paper raw materials consists of a two-chamber mass mixing pool 23, into which a collector 10 and an intake pipe 8 of a pump 6 are cut. A mixing device 6 is supplied to each of the chambers 2, which is designed with the possibility of being driven into rotation by an electric motor 21 via a drive belt 20 and a reducer or a bevel gear reducer, directly connected to the shaft 22 of the rotor of the electric motor 21. The intake pipe 8 is connected to a pressure box (not shown) via a pump 6 and feeds (not shown).

What is new is that the branch pipe 9 of the collector 10 and the intake branch pipe 8 of the pump 6 are cut into the mass pool 1 at an angle of 45° in different directions, while each of them is located on different sides of the partition 19, which is placed in the center of the pool 23 parallel to the walls 3 of the chambers 2 and extends along the length further than those edges of the chambers 2 to which the mixing devices 5 are connected.

Chambers 2 of pool 23 are formed by two partitions 3, which are placed in the middle part of pool 23 so that an inter-chamber zone 4 is formed between partitions 3.

Collector 10 is made to contain mass feeds (11, 12 - reject feeds, 13 - TMM, 14 - DVF, 15 - KVF, 16 - dye) and chemicals (17, 18), which are cut perpendicular to the axis of collector 10.

When the mass enters from the waste paper mass flow and the mass of TMP, rejects and chemicals (10-18), which are cut perpendicular to the axis of the collector 10, the mass swirls and the flow becomes more turbulent, which allows: to reduce the risk of clogging of the collector 10, as well as to increase the time and intensity of the primary mixing of the flows.

Primary mixing of the composition occurs in collector 10 in the zones of insertion of mass supplies (11 - 16) and chemicals (17, 18), further mixing occurs when passing through the zone of blades 25 of screws 24 of the mixer and in the middle section of the pool (interchamber zone 4).

The partition 19, which is placed in the center of the pool 23 parallel to the walls 3 of the chambers 2 and extends along the length further than those edges of the chambers 2 to which the mixing devices 5 are connected, is made in such a design and such a location in order to avoid the intake of insufficiently mixed (just received from the collector 10) mass. The installation of the partition 19 also allows stabilizing the direction of circulation of the mass flow. It acts as a flow divider.

If the partition 19 is placed on the top of the wedge-shaped protrusion 27 with a slope of α = 45°, the wedge of which is oriented inside the pool 23, and the intake pipe 8 of the pump 6 is introduced through the inclined surface of the wedge-shaped protrusion 27, then in addition to the partition 19, the role of a flow divider is also performed by the wedge-shaped protrusion 27, which also enhances the stabilization of the direction of circulation of the mass flow.

In a similar manner, the branch pipe 9 of the collector 10 and the intake branch pipe 8 of the pump 6, cut into the mass pool 1 at an angle of 45° in different directions, and at the same time located on different sides of the partition 19, are also oriented with the outlet and inlet openings, respectively, not counter to the mass flow, but sideways.

Thus, the masses circulate around the pool 23 for a long time and until they are completely mixed.

Insertion of pipes 9 and 8 into pool 1 at an angle of 45°, which also makes it possible to direct the flow of the mixture of waste paper mass and TMM mass to the axis 28 of the mixing device 5, that is, to direct the flow to pass the cycle through the compartment of the machine pool 23.

This design of the mixer as a whole allows to significantly increase the time required to improve the homogeneity of the flow.

The presence of filter 26 at the end of the intake pipe 8 of pump 6 allows for the selection of a mass of such fiber sizes that have already undergone segmentation by mixing cycles and are capable of passing through the pores of filter 26. Filter 26 is a cylindrical mesh with a rounded tip. During the process of mass suction through filter 26, its upper part (counter to the mass flow) becomes clogged, while the lower part does not become clogged and continues to suck in only sufficiently mixed masses capable of passing through filter 26.

It is permissible that instead of filter 26 a mesh is used, which is placed at the end of the intake pipe 8 or inside it.

From the mixing basin, the mass is directed to the suction side of pump 6 of the first stage of the cleaning plant. The mass is diluted to the concentration of the headbox and passes further through the first stage screens and the feed pump of the headbox. The mass is pumped through the machine screens into the headbox.

To regulate and control dehydration, chemicals 17, 18 are used to improve dehydration and fiber retention; to give the paper the required shade, a brown dye is used, which is fed through the pipe 16.

In the conditions of the existing shortage of high-quality waste paper (brands MS-5B, MS-6B), the use of the declared solution will allow to extract from waste and return to production difficult-to-process types of waste paper (water-resistant, grease-resistant, laminated...), the main volume of which is contained in the composition of MSW (municipal solid waste) and is currently not extracted due to the complexity of solving the problem of homogenizing the flow of waste paper mass (MM) going into the pressure box in known types of mixers.

In general, the implementation of this technology can serve as one of the areas for the successful implementation of the reform of the state waste management system in terms of paper and cardboard as part of MSW.

The use of TMM+MM as raw material improves the environmental and sanitary-hygienic indicators of the product in bulk due to the addition of primary fiber (TMM), which will reduce the requirements for barrier coatings (the possibility of using in the case of manufacturing consumer packaging - for example, for packaging pizza, takeaway pies, agricultural products, etc.). The use of primary fiber in the composition of the original raw material allows to reduce the consumption of chemicals, recycled water for washing, improve the quality of wastewater discharges, reduce the volume of waste paper recycling waste disposal. Ensures the rational use of acutely scarce waste paper raw materials and its partial replacement with primary fiber.

But without solving the problem of homogenizing the flow in the mixer, the use of a mixture of TMM+MM raw materials is not possible.

Using the claimed solution, mass mixing tests were conducted.

The tests showed the balances of the mixer operation in different operating modes with different additives (see Tables 1-8 below).

*Explanations for tables:

BDM - paper making machine,

DV MM - long-fiber waste paper pulp,

KV MM - short-fiber waste paper pulp.

Claims (10)

1. A unit for mixing paper pulp components during the processing of waste paper raw materials, consisting of a two-chamber mass mixing basin, into which a collector and a pump intake pipe are cut in, wherein a mixing device is supplied to each of the chambers, which is designed with the possibility of being driven into rotation by an electric motor via a drive belt and a gear reducer or a bevel gear reducer directly connected to the rotor shaft, the intake pipe is connected to a pressure box via a pump and inlets, characterized in that the collector pipe and the pump intake pipe are cut into the mass basin at an angle of 45° in different directions, and each of them is installed on different sides of a partition, which is installed in the center of the basin parallel to the walls of the chambers for a length extending beyond those edges of the chambers to which the mixing devices are supplied. 2. The device according to item 1, characterized in that the partition is installed on the top of a wedge-shaped protrusion with a slope of 45°, the wedge of which is oriented towards the inside of the pool, and the suction pipe of the pump is inserted through the inclined surface of the wedge-shaped protrusion. 3. The device according to item 1, characterized in that the chambers of the pool are formed by two partitions, which are placed in the middle part of the pool so that an inter-chamber zone is formed between the partitions. 4. The device according to item 1, characterized in that the collector contains mass and chemical supplies cut into it perpendicular to its axis. 5. The device according to item 1, characterized in that a mesh filter is installed at the end of the pump intake pipe. 6. A method for mixing components of paper pulp during the processing of waste paper raw materials, in which the mixing of the masses fed through a collector is carried out, wherein the mixing is carried out in a closed cycle inside the pool using mixing devices, the mixed masses are taken from the pool using an intake pipe, through which they are directed into a pressure box using a pump, characterized in that the mixing of the components of the paper pulp is carried out using a mixing unit according to paragraph 1, the collector pipe and the intake pipe of the pump are cut into the mass pool at an angle of 45° in different directions, while each of them is located on different sides of the partition, which is placed in the center of the pool parallel to the walls of the chambers and extends along the length further than those edges of the chambers to which the mixing devices are connected. 7. The method according to item 6, characterized in that the partition is placed on the top of a wedge-shaped protrusion with a slope of 45°, the wedge of which is oriented inside the pool, and the intake pipe of the pump is inserted through the inclined surface of the wedge-shaped protrusion. 8. The method according to item 6, characterized in that the chambers of the pool are formed by two partitions, which are placed in the middle part of the pool so that an inter-chamber zone is formed between the partitions. 9. The method according to item 6, characterized in that the collector is made to contain supplies of masses and chemicals, which are cut perpendicular to the axis of the collector. 10. The method according to item 6, characterized in that a mesh filter is installed at the end of the pump intake pipe.