ES2403344T3 - Device and method related to fiber molding - Google Patents

Abstract

A method for the production of three-dimensional fiber-based molded panel products, the products produced in a production facility comprising a pulp preparation section (1) comprising a shredder (19) for preparing a grout of Paste, the disposer (19) connected to a training section (3), the training section (3) comprising a training tank (16) and a training unit (20), and a pouring water tank (5 ) which recycles wastewater from the training unit (20) to the pulp preparation section (1), in which a first tool of the training unit (20) is being immersed in the pulp slurry in the formation tank (16) characterized in that a retention agent is being added and mixed, said retention agent being ozone gas (31), to make the flocculation more efficient through a greater aggregation of particles more fine, in at least one of the following positions: 1) the pouring water tank (5) 2) between the pouring water tank (5) and the pulp preparation section (1) 3) the Preparation of pulp (1), 4) the formation tank (16) and 5) between the formation unit (20) and the pouring water tank (5).

Description

Device and method related to fiber molding.

FIELD OF THE INVENTION

The invention relates to the production of fiber products from pulp and especially to three-dimensional objects such as "clam shells" containers, and other packaging products but also to objects such as drinking glasses for drinks or trays. , for example food trays; as is known for example from WO 97/22755.

BACKGROUND OF THE INVENTION

Flocculation is one of the essential phenomena in a molded panel process. This affects both the ease of operation of the machine and the quality of the final product and the training control, which is one of the most important goals of the manufacturing process. Flocculation is understood as a gathering of fibers, very short pulp fibers and fillers present in a float in flocs. The flocculation phenomenon can be divided into two different phenomena, of which one is flocculation of mainly small particles, that is, very short fibers of wood-based and mineral-based pulp, chemicals, impurities such as resins, and occasional fibers. They add in smaller groups. Small particle flocculation usually requires an auxiliary agent, such as a retention chemical, the effect of which is based on electrostatic interactions. The second phenomenon refers to aggregation of larger groups and is mainly a mechanical flocculation of fibers based on the dimensions of the suspended fibers and the consistency of the suspension. However, the second phenomenon is undesirable, that is, the flocculation of larger groups; and it is often prevented by keeping the grout at a constant flow.

The first phenomenon, on the contrary, is desirable. Smaller particle flocculation affects the retention of smaller particles and, in addition, the process and product quality factors dependent on such retention. The retention of smaller particles prevents clogging of the formation tools; it also reduces these particles in the pouring water since they stick to the fiber web. In addition, the raw material is used more efficiently if more of it adheres to the fiber web. In addition, the very shortest pulp fibers that remain in the pouring water increase the growth of microorganisms, and having smaller particles flowing around in the system can lead to problems such as silt formation, clogging, as well as production and altered product qualities. The water quality of the recycled process always tends to be gradually altered to a greater "closure" or reuse (recycling degree) in the production facility due to said small waste described above. In turn, this leads to a gradual effect of quality alteration, both on the actual production process and on the product produced in the production facility. This is a fundamental problem.

The invention relates to how to improve the first phenomenon, flocculation of mainly small particles, described above.

In addition, ozone has previously been used to destroy microbiological cultures, to decompose contaminants comprising COD and BOD, to bleach substances in the final product.

US Patent No. 4083749 discloses a method of manufacturing a glued paper where an aqueous pulp slurry containing a cationic neutral sizing agent or a wet sheet prepared therefrom is treated in an oxidizing agent, for example ozone.

Document FI 110683B discloses a method of using ozone to destroy microorganisms in the water of the internal process in a paper mill.

However, in the prior art, ozone gas has not been used as a retention additive or as a catalyst for other retention additives.

It is an object of the invention to provide a device and method where the pouring water and / or the slurry are subjected to ozone gas, where the ozone gas functions as a retention agent and as a catalyst for retention agents Conventional ones that make flocculation more effective by improving flocculation mainly according to the first phenomenon. Therefore, the ozone gas operates simultaneously as a bleaching agent, and further reducing the content of BOD and COD as well as destroying microorganisms.

SUMMARY OF THE INVENTION

According to the invention, a method according to claim 1 is provided. The production installation further comprises a drying section after the forming section and where condensed water from the drying process of the drying section is supplies the spill water tank.

Additional retention agents are added to the pulp slurry in at least one of the following positions: 1) the pulp preparation section 2) the forming tank.

According to an embodiment of the invention ozone gas is added and mixed in a position before the addition of the retention agents. According to a further embodiment of the invention, ozone gas is added and mixed in a position after the addition of the retention agents and / or together with the retention agents.

According to a further embodiment of the invention, sizing agents are added to the pulp slurry and the ozone gas is added and mixed in one position before the sizing agents are added.

Furthermore, according to the invention, a production installation according to claim is provided.

8.

In accordance with further embodiments of the invention, additional means of adding ozone gas are provided in at least one of the following positions 4) the pulp preparation section 5) the forming tank.

DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail by means of various embodiments thereof in reference to the accompanying drawings in which identical reference numbers have been used in the various figures of the drawings to indicate corresponding components.

Figure 1 schematically illustrates material and water flows in the production of molded three-dimensional paste objects, and

Figure 2 shows an embodiment of the addition and mixing of ozone gas in a tank containing fluid, and

Figure 3a shows a diagram of the substances in the pouring water where ozone gas and retention chemicals have been added to the pulp grout before a formation stage,

Figure 3b shows a diagram of the substances in the pouring water where ozone gas and retention chemicals have been added to the pulp slurry before a formation stage.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 schematically illustrates the material and water flows in the production of molded three-dimensional paste objects. On the left in Figure 1, a paper pulp preparation section 1 is indicated in which a pulp of slurry is mixed from pulp and water in one or more stages and where different chemical additives are added, the pulp slurry of the pulp preparation section 1 is supplied to the forming section 3 producing a product in the form of a three-dimensional molded panel, product that is dried in the next drying section 4, where the dried product can then be subjected to further treatments.

In more detail, the step of preparing pulp 1, pulp 6 and water, supplied through the first pouring water pipe 8 from the pouring water tank 5, is mixed in the disposer 19 to form a grout of pasta, for example pasta slurry having a paste concentration of 4% by weight. Preferably, the paste is provided through bales of pasta that disintegrate and dissolve in water. The paste used is preferably chemothermal-mechanical (CTMP) but a different CTMP paste can also be contemplated. CTMP is a preferred paste in this context, since it is relatively easy to dehydrate a slurry of CTMP-based paste. The mixed pulp slurry is subsequently passed to the storage tank 10 through a first supply pipe 9. Fresh water 7 can be used to clean the disposer 19 which is then supplied to the storage tank 10 by further diluting the pulp slurry, by example at a paste concentration of 3% by weight. In the storage tank 10, the pulp slurry can be kept moving by means of a stirrer to avoid flocculation according to the second phenomenon, that is the aggregation of larger groups. The pulp slurry is then passed to the machine tank 14 or through the second supply line 12. Pouring water through the second pouring water pipe 11 from the pouring water tank 5 is also supplied to the second supply line 12 to further dilute the pulp slurry, for example at a paste concentration of 1.5% by weight. In the machine tank 14, the pulp slurry can be kept moving by means of a stirrer to avoid flocculation according to the second phenomenon. The pulp slurry is then passed to the formation tank 16 of the formation section 2 through the third supply pipe

15. Pouring water through the third pouring water pipe 13 from the pouring water tank 5 is also supplied to the third supply pipe 15 to further dilute the pulp slurry, for example at a paste concentration of the 0.5% by weight.

A first tool of the formation unit 20 is immersed in the pulp slurry in the formation tank 16 and an embryonic fiber product is formed on the first tool by applying suction through the first tool. The first tool is then removed from the pulp and the first tool is carried against a second tool so that the fiber product formed is sandwiched between the first and the second tool. The fiber product formed is heated by the second tool, so that at least a part of the water in the fiber product formed is vaporized, vaporized water that is evacuated through suction. This process can be repeated in several stages of heating and pressing and, when the fiber product has reached a desirable dry solid content, preferably at least 70%, it can be subjected to a final microwave drying in the drying section 4, by microwave oven or ovens 23. Before final drying by microwave, the fiber product can be steamed to achieve a more evenly distributed moisture content. The dried fiber product leaving the drying section could be subsequently ready for use or subjected to further treatment such as, for example, rolling.

The water evacuated from the training unit 20, by suction through the tools, is recycled to the pouring water tank 5 through the fourth pouring water pipe 18. From the drying section the condensed water can be recycled to the discharge water tank 5 through the fifth discharge water pipe 22.

In the pouring water tank 5, the pouring water can be kept moving by means of a stirrer. If necessary, fresh water could be supplied to the pouring water tank 5. Additional pouring water could also be evacuated from the pouring water tank 5 possibly to an external purification section.

Chemical additives such as sizing agents, moisture resistance agents, retention agents, coloring chemicals, paste slurry agents in any appropriate position from the crusher 19 could be added to the formation tank 16, including the crusher 19 and the training tank 16.

In accordance with the preferred embodiment of the invention, the pouring water tank 5 is configured with an ozone gas addition and mixing equipment as shown in Figure 2. Ozone degrades rapidly, since ozone is an unstable compound with a relatively short half-life. Ozone partially degrades into reactive OH radicals. Therefore, the evaluation of an ozone process always involves the reactions of two species: ozone and OH radicals. Ozone, as well as OH radicals, can react with substances in the water as well as with the water itself. The pouring water is being “charged” and becomes chemically active. As the discharge water is supplied to the disposer 19, the second supply line 12 or the third supply line 15, the "charged" discharge water promotes the aggregation of the finest particles and enhances the effects of retention agents acting as a type of catalyst for the polarization between particles, substances and additives suspended in water.

That is, the ozone gas provides the advantages of 1) acting as a retention agent that promotes the aggregation of finer substances to form small groups, whereby more substances stick in the fiber band which increases the yield of the input materials, reduces the obstruction of the tools of formation, increases the capacity of dehydration that allows a greater quality of production and / or reduce the consumption of energy of dried and dehydrated 2) to enhance the effects of other chemical products in particular agents Conventional retention agents that reduce the amount of retention chemicals needed. In addition, using ozone gas, additional advantages are achieved: 3) microorganisms are destroyed which reduces the foam, silt and other effects of the microorganisms by reducing water consumption and allowing the water system to be more closed 4) the content of BOD and COD is lowered, which also reduces water consumption and allows the water system to be more closed and if part of the water is dumped into a sewer, less or no additional purification is needed 5) impurities are bleached reducing the discoloration of the products.

Preferably, between the ozone gas in the amount of 3-30 g / m3, pouring water is added to the pouring water tank 5, more preferably 4-20 g / m3. The amount of ozone gas supplied 31 depends on factors such as, the amount of substances in the fluid, the desired bleaching effects, economic factors, etc.

An exemplary embodiment of the addition and mixing of ozone is shown in Figure 2. A fluid 33, for example fiber slurry or pouring water, is pumped into the tank 24. For example, the storage tank 10, The machine tank 14 and / or the pouring water tank 5 could be configured similarly to the tank 24. As shown in the figure, the fluid 33 enters the tank 24 through a fluid inlet 26 at the top of the tank 24. The fluid 33 can be evacuated through the outlet 30 and the valve 28 at the bottom of the tank 24. Ozone gas 31 is injected, through the ozone injection nozzles 25, at inside the tank 24 in the form of small bubbles to thereby increase the contact surfaces with the fluid 33 and particles and chemicals contained therein. The ozone gas 31 is preferably generated by an ozone generator. Preferably, an agitator 27 is located inside the tank 24, to stir the fluid 33 to further increase the chances of the ozone gas bubbles 31 reacting with the substances in the fluid 33, as well as to prevent group aggregations. larger, that is flocculation according to the second phenomenon. Suitably, other means of agitation for the fluid 33 can be used. The upper part of the tank 24 is provided with outlet pipes 29, 34 for the evacuation of the remaining ozone gas 31 that has passed through the fluid 33 without having reacted. In addition, other gases could be evacuated through the outlets 29, 34. The remaining ozone gas 31 can be conducted through the pipe 29 to an ozone destroyer, or it can be returned to the ozone generator through the pipe 34, for reuse for then be recycled to tank 24.

It is preferred to provide a contact time between the ozone gas 31 and the fluid 33 that is as long as possible, allowing the ozone gas 31 to react with the fluid 33 and the substances contained therein. The tank 24 facilitates this, but the ozone gas 31 could also be supplied in a pipe in which the ozone gas 31 is mixed with the flowing fluid 33, A combination of a tank 24 with an agitator 27 and a pipe with a mixer static, it is also possible. The flow rate of the fluid in the tank 24 as well as through a static mixer affects the amount of ozone gas 31 necessary to achieve the desirable reactions. A high traffic flow can be compensated by a higher concentration of ozone gas 31.

Figure 3a and Figure 3b show the effect on the substances in the pouring water using ozone gas and retention agents according to an experiment carried out in a paper mill. Retention agents and ozone gas were added to the pulp slurry at a stage prior to formation. In Figure 3a, retention agents were added between the times: t = 3.3 and t = 19.6; between t = 12.7 and t = 19.6, ozone gas was also added and mixed. The time t in hours. As can be seen, the retention agents alone allowed a reduction of substances of 0.9 g / l. The combination of ozone gas and retention agents allowed a further reduction of substances of 0.6 g / l. In Figure 3b ozone gas was added and mixed between the times: t = 3.0 and t = 17.5; between t = 11.7 and t = 17.5, retention agents were also added. The time t in hours. As can be seen, the ozone gas alone allowed a reduction of substances of 0.4 g / l. The combination of ozone gas and retention agents allowed an additional reduction of substances of 1.1 g / l. As is also evident from the figures, there is a combination effect of the retention agents and the ozone gas, the combination effect of approximately 0.2 g / l. Therefore, during this experiment, the retention agents allowed ~ 60% of the substance reduction, while ozone allowed ~ 27% and the combination ~ 13%. In both experiments the temperature of the pulp slurry and the pouring water was ~ 45 ° C and the pH of -6.5-7.0. The pulp slurry was supplied with ozone gas in an amount of 5 g / m3 of slurry corresponding to -0.4-0.5 kg of O3 per ton of fiber product produced. The retention agent supplied was PAM + Bentonite. The amount of Bentonite supplied was 7 kg of Bentonite per ton of fiber product produced. The amount of PAM supplied was 0.5 kg of Pam per ton of fiber product produced. In the experiments, when ozone gas and retention agents were used in combination, the production speed increased 5%, but was prevented from increasing further due to the mechanical limits of the apparatus. Instead, the effect was used to increase dehydration and drying energy was reduced by 25-30%.

Although the invention has been shown and described in relation to the preferred embodiment thereof, it will be understood that many modifications, substitutions, and additions can be made that are within the intended scope of the following claims. From the foregoing, it can be seen that the present invention meets at least one of the stated objectives.

The addition and mixing of ozone gas 31 can also be facilitated by an addition and mixing pump such as a type of turbine pump, or by adding ozone gas 31 into a pipe by means of the help of a so-called ejector or by a lance dosing, as well as other mixing means.

In addition, ozone gas 31 could also be added and mixed in the first, second, third, fourth and fifth water pipes 8, 11, 13, 18, 22 respectively, preferably using a static mixer. In addition, ozone gas 31 could also be added and mixed in the first, second and third supply lines 9, 12, 15 respectively, preferably using a static mixer. Additional ozone gas 31 could also be added and mixed in the disposer 19, the storage tank 10 and / or the machine tank 14. The ozone addition and mixing positions mentioned above could be used independently or in combination with other positions of ozone addition and mixing.

In addition, ozone gas 31 can be added before the addition of sizing agents.

Of course, different dryers from microwave dryers 23 could be used in drying section 4.

Claims (9)

1. A method for the production of three-dimensional fiber-based molded panel products, the products produced in a production facility comprising a pulp preparation section (1) comprising a shredder (19) for preparing a paste slurry, the grinder (19) connected to a training section (3), the training section (3) comprising a training tank (16) and a training unit (20), and a pouring water tank (5) that recycles wastewater from the training unit

(twenty)

 to the pulp preparation section (1), in which a first tool of the training unit

(twenty)

 it is being immersed in the pulp slurry in the formation tank (16) characterized in that a retention agent is being added and mixed, said retention agent being ozone gas (31), to make the flocculation more effective through greater aggregation of finer particles, in at least one of the following positions: 1) the spill water tank (5) 2) between the spill water tank (5) and the pulp preparation section (1 ) 3) the pulp preparation section (1), 4) the formation tank (16) and 5) between the formation unit (20) and the pouring water tank (5).

2.

Method according to claim 1, wherein the production installation further comprises a drying section (4) after the forming section (3) and wherein condensed water from the drying process of the drying section ( 4) It is supplied to the pouring water tank (5).

3.

Method according to any preceding claim, wherein additional retention agents are added to the pulp slurry in at least one of the following positions: 1) the pulp preparation section (1) 2) the forming tank ( 16).

Four.

Method according to claim 3, wherein ozone gas is added and mixed in a position before the addition of the retention agents.

5.

Method according to claim 3 or 4, wherein ozone gas is added and mixed in a position after the addition of the retention agents.

6.

Method according to any of claims 3 to 5, wherein the ozone gas is added and mixed together with the retention agents.

7.

A method according to claim 1, wherein sizing agents are added to the pulp slurry and wherein ozone gas is added and mixed in a position before the sizing agents are added.

8.

A production facility comprising a pulp preparation section (1) comprising a shredder (19) for preparing a pulp of grout, the shredder (19) connected to a forming section (3), the forming section comprising (3) a training tank (16) and a training unit (20), and a pouring water tank (5) arranged to recycle pouring water from the training unit (20) to the preparation section of paper pulp (1) in which a first tool of the forming unit (20) is immersed in the pulp slurry in the forming tank (16), characterized in that means for adding retention agent are provided in at least one of the following positions: 1) the pouring water tank 2) between the pouring water tank (5) and the pulp preparation section (1) and 3) between the forming unit (20) and the tank of pouring water (5), said retention agent being ozone gas.

9.

A production facility according to claim 8, wherein ozone gas addition means are additionally provided in at least one of the following positions 4) the pulp preparation section (1) 5) the formation tank (16).