Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/04—Addition to the pulp; After-treatment of added substances in the pulp
  • D21H23/06—Controlling the addition
  • D21H23/12—Controlling the addition by measuring properties of the formed web
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/78—Controlling or regulating not limited to any particular process or apparatus
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
  • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
  • D21H17/675—Oxides, hydroxides or carbonates
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
  • D21H17/70—Inorganic compounds forming new compounds in situ, e.g. within the pulp or paper, by chemical reaction with other substances added separately

Definitions

• the invention relates to a method for producing a fibrous web in a machine comprising a headbox, a wire section, a press section and a drying section, using a first fiber-containing suspension, in which the fibers in a reactor are at least partially mixed with one by a precipitation process Proportion of the ash-forming precipitation product contained in the fibrous web are loaded.
• US Pat. No. 5,223,090 describes a process for producing a fiber suspension containing a precipitation product, namely calcium carbonate, in which fiber material with elongated fibers with a cell wall surrounding a cavity is used, the fibers having a moisture content which is sufficient to dehydrate them To form pulp of a pulp.
• the fibers have a moisture content that corresponds to a proportion of 40 to 50% of the weight of the fibers.
• the water is essentially present inside the fibers and inside the fiber walls.
• calcium oxide or calcium hydroxide is added to the pulp, so that at least a part of the calcium oxide or calcium hydroxide introduced is associated with the water present in the pulp.
• the fibrous cellulosic material is then contacted with carbon dioxide while simultaneously being subjected to a shear mixing process to produce a fibrous material with a substantial amount of calcium carbonate in the hollow interior and within the fiber walls of the cellulosic fibers.
• DE 102 04 254 A1 relates to a process for the preparation of fibers contained in a fiber suspension, in which the fibers loaded with the precipitation product are milled in a range from approximately 0.05 to approximately 5 ⁇ m to produce maximum dimensions of the precipitation product particles. Crystalline precipitate particles are generated. The crystalline precipitation product particles are generated in an online process directly in the stock preparation line.
• Papers containing fillers or ashes can be used for a large number of purposes, for example for the production of cigarette paper which has a weight per unit area of between 16 and 26 g / m 2 . It is often watermarked and is said to be very thin, smoldering and tasteless. In addition, it should have good optical values with regard to the degree of whiteness. The smoldering ability is mostly achieved by impregnation to leave a good-looking white ash. Cigarette paper is mostly made from linen or hemp fibers, cotton, sulfate pulp, paper machine waste and other fiber sources. The filler content of cigarette paper is between 5 and 40%, with 30% being regarded as the standard value.
• the fiber loaded with calcium carbonate can also be used for the production of packaging paper and cardboard.
• Packaging papers are usually produced as a multi-layer product with basis weights over 150 g / m 2 .
• the degree of grinding varies from 600 to 50 CSF or 20 to 80 ° SR, based on the end product produced.
• Sack papers require high porosity and high mechanical strength in order to meet the high requirements that arise from the rough treatment during the filling process and during the period of use, such as for cement bags.
• the paper must be strong enough to absorb impacts and, accordingly, have a high energy absorption rate.
• the sack paper must also be porous and sufficiently permeable to air to ensure easy filling.
• Sack papers are typically made as a product with basis weights between 70 and 80 g / m 2 from a long fiber kraft pulp and with a freeness between 600 to 425 CSF or 20 to 30 ° SR.
• a medium degree of grinding as described above, is aimed for, which is usually achieved by high-consistency grinding, while low-consistency grinding is used in conventional types of paper, for example in graphic papers.
• the result of the high-consistency grinding is a good bond between the fibers and a high porosity.
• the sack kraft paper is predominantly made from bleached and unbleached fibers, and a filler content of 5 to 15% can be present in the sack paper produced.
• Filter paper needs a high controlled porosity and pore distribution. It must have sufficient mechanical strength to counter the flow of the medium to be filtered. Filter paper is produced with a basis weight of 12 to 1200 g / m 2 .
• an air filter it is between 100 and 200 g / m 2 , with an oil and fuel filter between 50 and 80 g / m 2 , with a food filter up to 1000 g / m 2 , with a coffee filter up to 100 g / m 2 m 2 , for a tea bag between 12 and 20 g / m 2 and for a vacuum cleaner bag between 100 and 150 g / m 2 .
• All filters are made from a variety of fibers such as cellulose fibers, bleached and unbleached fibers, kraft pulp, DIP (deinked) paper, recycled fibers, TMP (thermomechanical) paper, etc., with a grinding degree of 600 to 350 CSF or from 20 to 35 ° SR is sought.
• fibers such as cellulose fibers, bleached and unbleached fibers, kraft pulp, DIP (deinked) paper, recycled fibers, TMP (thermomechanical) paper, etc.
• the retention of the fibrous web in the wire section is regulated in that the amount of the retention agent is replenished in accordance with the material densities measured in the white water and in the headbox. It has been shown that retention control leads to a better constant maintenance of the properties of the fibrous web, for example the consistency or the sheet properties, and advantageously affects the runnability of the paper machine, i. H. their efficiency, as well as the paper quality.
• this object is achieved in a method of the beginning mentioned type solved in that the ash content in the fibrous web produced from the fibrous suspension is measured during the production of the fibrous web and that the supply of the precipitate to the pulp suspension fed to the headbox is regulated on the basis of the measured ash content of the fibrous web.
• a method is particularly advantageous in which the ash content of the pulp suspension made available to the machine is regulated by mixing in accordance with the measured value from the first pulp suspension and a second pulp suspension containing at least essentially no precipitation products and then fed to the headbox.
• the ash content of the fiber suspension made available to the machine in the first fiber suspension is regulated by metering a first substance to be precipitated and a second substance which causes the precipitation reaction and thereby produces the precipitation product in the first fiber suspension.
• the calcium carbonate precipitation product which is precipitated from calcium hydroxide by means of carbon dioxide, is advantageous.
• the method is also advantageously designed such that the pH of the first fiber suspension is regulated in the reactor during the precipitation to produce the precipitation product. It is advantageous here if the respective pH value is compared with a correspondingly predeterminable target value and the control deviation is reduced or eliminated via at least one of the following process control variables: residence time of the fiber reaction in the reactor, inflow rate of the fiber suspension, pressure of the carbon dioxide, temperature of the fiber suspension and / or the calcium hydroxide, pressure in the reactor, temperature and / or pressure of the carbon dioxide, concentration of the carbon dioxide in the liquid phase, concentration of the calcium hydroxide and the fibers, by a specific fiber surface.
• the invention also relates to a machine for performing a method.
• the machine is characterized in that a measuring arrangement for measuring the ash content is arranged in the machine, in particular in the wire section, the press section, the dryer section or after the dryer section, which is connected via a signal line to a device for producing the fiber suspension arranged controller is connected.
• the machine thus has a control device for adjusting or regulating the ash content of the fibrous web produced from the fibrous suspension, ie. H. in the area of the paper machine after the headbox.
• the invention ensures constant processes for producing a fibrous web, which leads to an increase in quality and efficiency. It is no longer necessary to add fresh ash. Retention agent is saved, and the ash content introduced into the fiber suspension by fiber loading can be maximized by adjusting its content by direct regulation or control. This simplifies the overall process and significantly reduces the proportion of ash not bound to the fibers.
• the controlled variable of the fiber loading process for adjusting the ash content in the paper is the addition of the calcium hydroxide content.
• the proportion of ash in the fibrous material loaded with calcium carbonate is between 0.05 and 60%, preferably between 1 and 40%.
• FIG. 1 is a schematic view of a device for loading fibers contained in a fiber suspension with a filler by a chemical precipitation reaction with a pump disperser
• FIG. 2 shows a view of the pump disperger according to FIG. 1 in the direction of arrows A
• FIG. 3 shows a machine for producing a fibrous web in a simplified representation
• FIG. 4 shows a diagram of the control arrangement.
• a fiber suspension is fed to a pump disperger, ie a pump buffer 12, in a device 10 (FIG. 1) and is subjected to shear forces in this device in order to break up the fiber material into individual fibers, ie to expose the surfaces of the fibers and accordingly to enlarge the contact area.
• the pump disperger 12 is also used as a reactor for a chemical precipitation reaction. In particular, it can be designed such that a reduction in the flow rate of the fiber suspension results in a reaction channel 14. In the present case, it is designed such that the fibrous suspension is generally transported radially outward from a central, radially inner region.
• a static mixer can also be used.
• the reaction channel 14 of the pump disperger 12 is at least partially limited by structured surfaces, which can each be formed, for example, by a set of teeth or knives.
• the reaction channel 14 is formed between two opposing plates 16 with structured surfaces, between which the fiber suspension is transported radially outwards.
• a plug screw 18 is connected upstream of the pump disperger 12 in order to compress the fiber suspension to form a plug.
• the plug screw 18 is preceded by a feed screw 20, which is arranged in an at least substantially cylindrical channel or housing 22.
• the channel 22 has a connection 24 for supplying a mixture which, for example, consists at least of the fiber suspension, water and calcium oxide and / or calcium hydroxide.
• the plug screw 18 is rotatably arranged in a conical channel 26, the cross section of which tapers in the material flow direction S in order to compress the fibrous suspension by forming a plug in a channel 28 which adjoins the plug screw 18 and is arranged directly in front of the pump disperger 12.
• This channel 28, which is arranged directly in front of the pump disperger 12 is provided with a screw conveyor 30 and has a connection 32 for the direct introduction of carbon dioxide into the fiber suspension, which is no longer liquid but still moist.
• the screws 18, 20, 30 either have a common drive shaft 34, or they can at least partially be driven separately.
• the plug is loosened by a swirl cross 36 provided in the center of the plug screw 18, and the surfaces of the fiber material are correspondingly enlarged.
• the opposing structured surfaces of the plates 16 generate shear forces in the fiber material, which increases the contact area of the carbon dioxide reacting with the calcium hydroxide attached to the fibers and thus ensures a quick and efficient reaction.
• the pump disperger 12 has an outlet 38, which is arranged at least substantially tangentially to the plates 16, for the thickened loaded fibrous suspension.
• a carbon dioxide supply can also be provided in this area in order to set the desired pH.
• the pump disperser 12 can have an inlet 40, which is arranged at least substantially tangentially to the plates 16, for diluting the loaded substance with water and / or calcium hydroxide, in particular from an upstream substance thickening, to less than 6%, preferably between 3 and 6%. The material becomes pumpable again through the appropriate dilution.
• the fibrous suspension is produced, for example, by dissolving pulp or waste paper with additives in a pulper 42 or fed to the loading process as a non-dried fibrous material.
• Calcium oxide or calcium hydroxide is then added in a region 44 and mixed with the fiber suspension.
• the fiber suspension is then thickened in a region 46 by dewatering until a still moist slurry is formed. This creates a fiber suspension that is no longer liquid, but still moist.
• the loaded fiber suspension is then passed from the area 46 into the pump disperser 12, in which the carbon dioxide is introduced.
• FIGS. 1 and 2 for loading fibers contained in a fiber suspension with a filler is only one possible device out of a large number of possible devices.
• Further devices with exemplary character are, for example, also from the already mentioned German patent application DE 100 33 979 A1 and DE 102 04 254 A1 are known, the German patent application “FL-roch Ash content "of the applicant with the registration number HPP11846 DE shows a possible device.
• a machine 48 (FIG. 3) adjoining the area for fiber preparation shown in FIGS. 1 and 2 for producing a fibrous web 50, which has a headbox 52, a wire section 54, a press section 56, a dryer section 58, an applicator 60 for Applying glue and calenders 62, 64 and a winding device 66, there is a measuring arrangement 68 for online measurement, the ash content of the fibrous web 50, which either in the wire section 54, in the press section 56 or in the dryer section 58 or after this, for example in front of the calender 64.
• the positioning of the measuring arrangement 68 in the dryer section 58 is particularly suitable.
• the measuring arrangement 68 is connected via a signal line 70 to a controller 72 (FIG. 4) arranged in or after the device 10 for regulating the composition of the fiber suspension.
• the measuring arrangement 66 detects, for example optically, the ash content of the fibrous web 50 as a controlled variable and forms an electrical signal variable therefrom, which it supplies to the controller 72. This in turn generates signal quantities for the addition of calcium oxide or calcium hydroxide 74, for the associated stoichiometric addition of carbon dioxide 76, for the addition of dilution water 78 and for the addition of further chemicals 80, for example a retention agent, in an area 82 which is either within the Reactor for the production of the loaded fiber-containing fiber suspension or after this is arranged.
• the controller 72 preferably also regulates, if present, the addition or admixture of a fibrous suspension fed from another device via a line 84 through a valve 86, the fibers of which are not loaded with calcium carbonate, in order to reduce or increase the proportion of the fibrous suspension with loaded fibrous material increase, which is fed to the headbox 52 via a line 88.

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ID=34968616

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Cited By (2)

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Citations (2)

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• 2004
  • 2004-06-09 DE DE102004028047A patent/DE102004028047A1/de not_active Withdrawn
• 2005
  • 2005-06-01 WO PCT/EP2005/005862 patent/WO2005121451A1/de active Application Filing
  • 2005-06-01 CA CA002569884A patent/CA2569884A1/en not_active Abandoned
  • 2005-06-01 CN CNA2005800178658A patent/CN1961119A/zh active Pending
  • 2005-06-01 RU RU2006146943/12A patent/RU2006146943A/ru not_active Application Discontinuation
  • 2005-06-01 EP EP05745080A patent/EP1759060A1/de not_active Withdrawn
• 2006
  • 2006-12-08 US US11/608,387 patent/US20070107860A1/en not_active Abandoned

Patent Citations (2)

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