SE530340C2 - Device and method in connection with fiber forming - Google Patents

Description

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

Furthermore, ozone has previously been used to kill microbial cultures, to decompose pollutants including COD and BOD, to bleach substances in the final product.

U.S. Pat. 4083749 describes a method of producing a glued paper in which an aqueous slurry of pulp containing a cationic neutral sizing agent or a wet sheet prepared therefrom is treated with an oxidizing agent, e.g. ozone.

Fl 110 683B describes a method that uses ozone to kill microorganisms in the internal process water of a paper mill.

In the prior art, however, 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 an apparatus and method in which the backwater and / or pulp sludge is exposed to ozone gas, the ozone gas acting as a retention aid and as a catalyst for conventional retention aids, which makes the increase more effective by improving the increase mainly according to the first the phenomenon. The ozone gas thus acts as a bleaching agent at the same time as it lowers BOD and COD content and kills microorganisms.

BRIEF DESCRIPTION OF THE INVENTION According to the invention, there is provided a method of making three-dimensional, ber-based, molded cardboard products, which products are made in a production plant comprising a stock preparation section comprising a wafer for preparing a pulp slurry, which wafer section is connected to a mold section. comprises a forming tank and a forming unit, and a rear water tank which recirculates rear water from the forming unit to the stock preparation section where ozone gas is mixed in, to make the increase more efficient by increasing aggregation of the particles, in at least one of the following positions: 1) the rear water tank, 2) the rear water tank and the sewage preparation section, 3) the stock preparation section, 4) the forming tank, and 5) between the forming unit and the rear water tank. The production plant further comprises a drying section after the forming section, wherein condensed water from the drying process in the drying section is supplied to the rear water tank.

Additional retention aids are added to the pulp sludge in at least one of the following positions: 1) the stock preparation section, 2) the forinning tank.

According to an embodiment of the invention, ozone gas is mixed into a position before the addition of the retention aids. According to a further embodiment of the invention, ozone gas is mixed into a position which follows the addition of the retention aids and / or in connection with the retention aids.

According to a further embodiment of the invention, sizing agent is added to the pulp slurry and the ozone gas is mixed into a position before the addition of the sizing agents.

According to the invention, there is further provided a production plant comprising a stock preparation section comprising a store for preparing a pulp sludge, which store is connected to a forming section, which forming section comprises a forming tank and a feed unit, and a backwater tank arranged to recycle the backwater from the stock , the means for adding ozone being arranged in at least one of the following positions: 1) the rear water tank, 2) between the rear water tank and the stock preparation section, and 3) between the forming unit and the rear water tank.

According to further embodiments of the invention, means for adding ozone are further provided in at least one of the following positions: 4) the stock preparation section, 5) the forming tank.

DESCRIPTION OF THE FIGURES The invention will in the following be described in greater detail by various embodiments thereof with reference to the appended figures in which identical numerical references have been used in the various figures to denote corresponding components.

F ig. 1 schematically illustrates the fate of materials and water in the production of molded three-dimensional pulp objects, and Fig. 2 shows an embodiment of the mixing of ozone gas in a tank containing a fluid, and Figs. Fig. 3a shows a diagram of the substances in the backwater when ozone gas and retention chemicals have been added to the pulp slurry before a forming step;

DETAILED DESCRIPTION OF THE INVENTION Fig. 1 schematically illustrates the fate of materials and water in the production of molded three-dimensional pulp objects. To the left in F ig. 1, a pulp slurry section 1 is indicated in which a pulp sludge in one or two steps is mixed with pulp and water and in which various chemical additives are added, the pulp sludge from the pulp slurry section 1 being fed to the molding section 3 and giving a three-dimensional molded paper product, which product is dried in the following the drying section 4, after which the dried product can be subjected to finishing treatments.

In more detail, in the stock preparation step 1, pulp 6 and water supplied through the first backwater line 8 from the backwater tank 5 are mixed in the opener 19 to form a pulp sludge, e.g. a pulp sludge with a pulp concentration of 4% by weight. The pulp is preferably supplied through pulp bales which are dissolved and dissolved in water. The pulp used is preferably chemitromechanical pulp (CTMP), but pulp other than CTMP is also conceivable. CTMP is a preferred pulp in this context, as it is relatively easy to dewater a pulp sludge based on CTMP. The mixed pulp sludge is then fed via a first supply line 9 to the storage tank 10. Fresh water 7 can be used to clean the store 19, which water is then supplied to the storage tank 10 to further dilute the pulp sludge, e.g. to a pulp concentration of 3% by weight. In the storage tank 10, the pulp sludge can be kept in motion by means of a tube stirrer to avoid increase according to the second phenomenon, i.e. aggregation of larger groups. The pulp sludge is then fed via the second supply line 12 to the machine tank 14. Backwater is also fed via the second back water line 11 from the back water tank 5 to the second supply line 12 to further dilute the pulp sludge, e.g. to a pulp concentration of 1.5% by weight. In the machine tank 14, the pulp sludge can be kept in motion by means of a tube stirrer to avoid flocculation according to the second phenomenon. The pulp sludge is then passed via the third supply line 15 to the forming tank 16 in the forming section 2. Backwater is also dried via the third backwater line 13 from the backwater tank 5 to the third supply line 15 to further dilute the pulp sludge, e.g. . to a pulp concentration of 0.5% by weight.

A first tool in the forming unit 20 is immersed in the pulp slurry in the forming tartar 16 and an embryonic carrier product is formed on the first tool by being placed on a suction through the first tool. Then the first tool is removed from the stock and the first tool is moved towards a second tool, so that the formed product is squeezed between the first and the second tool. The formed fiber product is heated by the second tool so that at least a portion of the water in the formed fiberprode evaporates, which evaporated water is evacuated by suction. This process can be repeated in fl your heating and pressing steps and when the fi berry product has reached a desired dry matter content, preferably of at least 70%, it can be subjected to final drying by means of microwaves in the drying section 4, by means of the microwave oven / ovens 23. Before final drying by means of microwaves, fi the berry product is exposed to steam in order to achieve a more even distribution of the moisture content. The dried fi berry product leaving the drying section may then be ready for use or may be subjected to finishing such as e.g. lamination.

The water evacuated from the forming unit 20, by suction through the tools, is recycled to the backwater tank 5 through the fourth backwater line 18. From the drying section, condensed water can be recycled to the backwater tank 5 through the fifth backwater line 22. In the backwater tank 5, the backwater can be kept moving by a stirrer. If necessary, fresh water can be supplied to the rear water tank 5. Furthermore, rear water can also be evacuated from the rear water tank 5, possibly to an external treatment section.

Chemical additives, such as sizing agents, wetting agents, retention aids, color chemicals, oxidizing agents, may be added to the pulp slurry in any suitable position from the opener 19 to the preform 16, including the opener 19 and the forming tank 16.

According to the preferred embodiment of the invention, the backwater tank 5 is designed with equipment for adding ozone and for stirring, as shown in Fig. 2. Since ozone is an unstable compound with a relatively short half-life, it decomposes rapidly. Ozone is partially broken down into reactive OH radicals. Therefore, the evaluation of an ozone process always involves the reactions of two substances: ozone and OH radicals. The ozone, and also the OH- 10 15 20 25 35 530 340 11947 radicals, can react with substances in the water as well as with the water itself. The backwater is "charged" and becomes chemically active. When the backwater is supplied to the store 19, the second supply line 12 or the third supply line 15, the "charged" backwater will promote the aggregation of small particles and improve the effect of the retention means by acting as a kind of catalyst for polarization between particles, substances and additives. which are suspended in the water.

In other words, the ozone gas provides the advantages of 1) acting as a retention aid that promotes the aggregation of small substances to form small groups, whereby a larger amount of substances gets stuck in the ban path, which increases the yield of the starting materials, reduces clogging of the forming tools, increases dewatering capacity higher production quality and / or reduction of energy consumption for drying and dewatering, 2) improve the effects of other chemicals, especially conventional retention aids, which reduces the amount of retention chemicals needed. In addition, additional benefits are achieved when using ozone gas: 3) microorganisms are killed, which reduces the formation of foam, mucus and other effects of microorganisms, thereby reducing water consumption and enabling the water system to be shut down to a greater extent, 4) the BOD and COD content is reduced, also reduces water consumption and enables the water system to be shut down to a greater extent and if some of the water is allowed to go to sewage, less or no treatment is needed, 5) impurities are bleached, which reduces discoloration of the products.

Preferably ozone gas is added in an amount between 3 and 30 g / m 3 to the backwater tank 5, more preferably 4-20 g / m 3. The amount of ozone gas 31 added depends on factors such as the amount of substances in the fl uiden, the desired bleaching effect, economic factors, etc.

An embodiment of the ozone mixture is shown in Figs. 2. And fl uid 33, tex. a ers berslanima or rear water, is pumped into the tank 24. The storage tank 10, the machine tank 14 and / or the rear water tank 5 can e.g. be designed in a similar way to the tank 24.

As shown in the figure, the liquid 33 enters the tank 24 via a liquid inlet 26 at the top of the tank 24. The fluid 33 can be discharged through the outlet 30 and the valve 28 at the bottom of the tank 24. Ozone gas 31 is injected into the tank 24 through the ozone injection nozzles 25, in in the form of small bubbles, thereby increasing the contact surfaces with fl uiden 33 and particles and chemicals contained therein. The ozone gas 31 is preferably created by means of an ozone generator. A stirrer 27 is preferably provided inside the tank 24 for agitating the liquid 33 to further increase the possibilities for the bubbles 31 of ozone gas to react with the substances in the liquid 33, as well as to prevent aggregation of larger groups, 530 340 11947 i.e. fl increase according to the second phenomenon. Other agitators may be used for the 33 uiden 33. The top of the tank 24 is provided with outlet lines 29, 34 for evacuating the remaining ozone gas 31 which has passed the fl uiden 33 without having reacted. Other gases can also be evacuated through the outlets 29, 34. The remaining ozone gas 31 can either be led via a pipe 29 to an ozone depletor, or it can be returned to the ozone generator via the line 34, for reuse and to be subsequently recycled to the tank 24.

It is preferred to provide a contact time between the ozone gas 31 and the fl uiden 33 that is as long as possible, which enables the ozone gas 31 to react with the fl uiden 33 and substances therein. The tank 24 facilitates this, but the ozone gas 31 can also be supplied to a line in which the ozone gas 31 is mixed with the flowing liquid 33. It is also possible with a combination of tank 24 with a stirrer 27 and a line with a static mixer. The flow rate of the fluid in the tank 24, as well as through a static mixer, affects the amount of ozone gas 31 needed to produce the desired reactions. A high throughput rate can be compensated by a higher concentration of the ozone gas 31.

F ig. 3a and 3b show the effect on the substances in the backwater when using ozone gas and retention aid according to an experiment carried out in a paper mill.

The retention aids and the ozone gas were added to the pulp slurry in one step before molding.

In Fig. 3a, retention aids were added between the times: t = 3.3 and t = 19.6; between t = 12.7 and t = 19.6, ozone gas was also mixed. Time t in hours. As can be seen, the retention agents alone gave a reduction in substances of 0.9 g / l. The combination of ozone gas and retention aid gave a further reduction of substances of 0.6 g / l. I F ig. 3b ozone gas was mixed in between the times: t = 3.0 and t = 17.5; between t = 11.7 and t = 17.5 retention aids were also added. Time t in hours. As can be seen, ozone gas alone gave a reduction in substances of 0.4 g / l. The combination of ozone gas and retention aid gave a further reduction of substances of 1.1 g / l. It is also obvious from the figures that there will be a combination effect of the retention aids and the ozone gas, a combination effect of approximately 0.2 g / l. Thus, during this experiment, the retention aids gave ~ 60% of the decrease in substances while ozone gave ~ 27% and the combination accounted for ~ 13%. In both experiments, the temperature of the pulp sludge and the backwater was ~ 45 ° C and the pH ~ 6.5 ~ 7.0. The pulp sludge was fed with ozone gas in an amount of 5 g / m3 pulp sludge, which corresponded to ~ 0.4-0.5 kg 03 per tonne of fi ber product produced. The retention aid added was PAM + bentonite. The amount of bentonite added was 7 kg of bentonite per tonne of fi ber product produced. The amount added 10 15 20 530 340 11947 PAM was 0.5 kg PAM per tonne of fi berb product produced. When ozone gas and retention aids were used in combination in the experiments, the production rate increased by 5% but could not increase further due to mechanical limitations of the devices. Instead, the effect was used to increase dewatering and the drying energy decreased by 25-30%.

Since the invention has been shown and described in connection with the preferred embodiment thereof, it is to be understood that many modifications, substitutions and additions may be made which are within the intended broad scope of the following claims. From the above described, it can be seen that the present invention achieves at least one of the stated objects. The mixing of ozone gas 31 can also be facilitated by a mixing pump such as a kind of turbine pump, or by adding the ozone gas 31 in a line by means of a so-called non-ector or by means of a metering lance as well as other mixing means.

Furthermore, ozone gas 31 can also be mixed into the first, second, third, fourth and fifth backwater lines 8, 11, 13, 18 and 22, respectively, preferably using a static mixer. Furthermore, ozone gas 31 can also be mixed into the first, second and third supply lines 9, 12 and 15, respectively, preferably using a static mixer. Furthermore, ozone gas 31 can be mixed into the store 19, the storage tank 10 and / or the machine tank 14. The above-mentioned positions for mixing ozone can be used alone or in combination with other positions for mixing ozone.

Furthermore, the ozone gas 31 can be added before the addition of sizing agent.

Of course, dryers other than microwave dryers 23 can be used in the drying section 4.

Claims (6)

530 340 11947 PATENT CLAIMS 10 15 20 25 30 35. Method for producing three-dimensional, fiber-based, molded cardboard products, which products are produced in a production plant comprising a stock preparation section (1) comprising a server (19) for preparing a pulp sludge, which server (19) is connected to a forming section (3) , which forming section (3) comprises a forming tank (16) and a forming unit (20), and a backwater tank (5) which recirculates backwater from the forming unit (20) to the stock preparation section (1), characterized in that ozone gas (31) is mixed in, to make the increase more efficient by increasing the aggregation of fine particles, in at least one of the following positions: 1) the rear water tank (5), 2) between the rear water tank (5) and the stock preparation section (1), 3) the stock preparation section (1), 4) the forming tank (16), and 5) between the forming unit (20) and the rear water tarik (5). . A method according to claim 1, wherein the production plant further comprises a drying section (4) after the forming section (3), wherein the condenser Sß-raï V fl ü fi n from the drying process in the drying section (4) is supplied to the rear water tank (5). . Method according to any one of the preceding claims, wherein the retention means are added to the pulp sludge in at least one of the following positions: 1) the needle preparation section (1), 2) the forming tank (16). . A method according to claim 3, wherein ozone gas is mixed into a position before the addition of the retention aids. . A method according to claim 3 or 4, wherein ozone gas is mixed into a position after the addition of the retention aids. . A method according to any one of claims 3 to 5, wherein ozone gas is mixed in in conjunction with the retention aids. . A method according to claim 1, wherein sizing agent is added to the pulp alarm and wherein ozone gas is mixed into a position before the addition of the sizing agents. 10 530 340 10. Production plant comprising a stock preparation section (1) comprising a store (19) for preparing a pulp sludge, which store (19) is connected to a forming section (3), which forming section (3) comprises a forming tank (16) and a forming unit (20) , and a rear water tank (5) arranged to recirculate rear water from the forming unit (20) to the stock preparation section (1), characterized in that the means for adding ozone are arranged in at least one of the following positions: 1.) the backwater tariken, 2.) between the rear water tank (5) and the stock preparation section (1), and 3.) between the supply unit (20) and the rear water tank (5). . Production plant according to claim 8, wherein means for adding ozone gas are further arranged in at least one of the following positions: 4.) stock preparation section (1), 5.) the shaping tank (1 6.).