DE10347920A1 - Method and device for loading a pulp suspension - Google Patents

Abstract

A device for loading a cellulose fiber pulp suspension (1) comprises an arrangement (2) of machines for loading the pulp suspension (1) with calcium carbonate, to which flue gas (3) containing carbon dioxide is supplied. The machines are followed by a degassing unit (6) for removing excess gas.

Description

The The invention relates to a method for loading a pulp suspension with calcium carbonate.

Several processes for loading pulp fibers with calcium carbonate are already known. In the US 6,413,365 describes a method in which fiber material is transported together with calcium oxide present in the suspension and / or calcium hydroxide via a feed line. From this, the pulp suspension is forwarded to a rotating distribution device. A reaction gas is introduced annularly into the pulp suspension; As a result, calcium carbonate crystals are formed in the pulp suspension. About the rotating distributor, the calcium carbonate crystals are distributed in the pulp suspension. This process is referred to as a fiber loading process.

In the DE 100 33 978 A1 describes a method for loading a pulp suspension, in which the pulp suspension, a calcium oxide and / or calcium hydroxide-containing medium and pure carbon dioxide or a carbon dioxide-containing medium are added. According to US 2002/0088566 A1, a combustion process is used for the production of carbon dioxide, which is in a process connection with the device for producing the pulp suspension. From the DE 101 20 637 A1 For example, a method of loading a pulp suspension is known in which the carbon dioxide is generated from the exhaust gas of a fuel or by lime burning. The carbon dioxide has a purity of between 65 and 99% and is contained, for example, in the exhaust gas of a power plant, an internal combustion engine, a boiler or a plant for the direct burning of fossil fuel.

It The object of the invention is a method of the aforementioned Kind of improving further.

• – Einbringen von Calciumhydroxid in flüssiger oder trockener Form oder von Calciumoxid in die Faserstoffsuspension,
• – Einbringen eines Kohlendioxid enthaltenden Rauchgases in die Faserstoffsuspension,
• – Ausfällen von Calciumcarbonat durch das in dem Rauchgas enthaltene Kohlendioxid und
• – Entfernen überschüssigen Rauchgases.

According to the invention, this object is achieved by a method having the following method steps:

• Introduction of calcium hydroxide in liquid or dry form or of calcium oxide into the pulp suspension,
• Introducing a carbon dioxide-containing flue gas into the pulp suspension,
• - Precipitation of calcium carbonate by the carbon dioxide contained in the flue gas and
• - Remove excess flue gas.

The invention describes a process for producing fiber-loaded precipitated calcium carbonate (FLPCC) and at the same time subjecting it to a grinding treatment in which the recycled fiber pulp raw material to be loaded, DIP (= deinked paper), secondary pulp , bleached or unbleached pulp, mechanical pulp, bleached or unbleached sulphate pulp, pulp, cotton, and / or hemp fibers (predominantly cigarette paper) and / or any pulp used on a paper machine. This applies regardless of whether the end product contains filler which has been produced by a precipitation process in batch reactors or by a milling process, or whether talc, titanium dioxide (TiO ₂ ), silicon, etc. are used. The milling process is also referred to as ground calcium carbonate (GCC).

If treated a pulp suspension with the fiber-loading technology results in a completely new product for the scope of the Paper production with new and improved properties compared to a product the state of the art. The fiber-loading technology allows direct in the stock preparation of a paper mill filler, in particular calcium carbonate, precipitate, on, evenly distributed and deposited in and between the fibers is as well as the treated pulp simultaneously during the precipitation process to undergo a grinding treatment.

The process for the production of precipitated calcium carbonate with simultaneous grinding treatment by means of the fiber-loading combination process is carried out in a conventional manner, including in addition to the publications mentioned above on the DE 101 07 448 A1 , the DE 101 13 998 A1 and the US Pat. No. 6,413,365 B1 is referenced.

With the FLPCC combination process described in this invention, the prior art filler material is replaced by the filler material made with the fiber-loading combination process technology. The field of application of the filler produced by the fiber-loading combination process technology covers the fields of application of the paper production of all types of paper including cigarette paper types, paper stocks, sack grades and paperboard and packaging paper grades having a filler content between 1 and 60% and / or a white topcoat have a filler content between 1 and 60%. The types of paper loaded and produced may be recycled paper, deinked paper (DIP), secondary pulp, bleached or unbleached pulp, mechanical pulp, bleached or unbleached sulphate pulp, or the like weft, linen, cotton and / or hemp fibers (predominantly for cigarette paper) and / or any stock on a paper machine, regardless of whether the end product contains filler.

With fibrous material made of fiber-loading combination process technology generally has a higher one drainage property as pulp produced by other methods; the drainage ability is 5 to 100 ml CSF or 0.2 to 15 ° SR depending on the required degree of grinding. Additionally owns the fabric produced by the fiber-loading process or the pulp a lower water retention capacity of 2 up to 25% depending from the raw material used for production. This allows a more effective production of various paper types such as FL (fiber-optic) copy and printing paper of all kinds, FL paper of all kinds, FL newsprint of all kinds and FL cigarette paper of all kinds, FL-B & P paper of all Type, FL sack paper of all kinds and FL filter paper, because the existing water of the stock suspension can be removed faster. Correspondingly faster also dries the fabric.

at FL cigarette paper, FL-B & P paper, FL sack kraft paper and FL filter paper that does not contain fillers need, can the free filler by means of an additional activated washing process before the grinding process, after the grinding process or after passing through the headbox or before being fed to the headbox Paper machine to be removed. This concerns the filler, which is not deposited on or in the fibers and accordingly can be washed out. The fibers themselves are still inside and outside with filler provided so that the positive effects of fiber-loading technology can be exploited.

The Fiber-loading technology can be used before or after the grinding process depending on the requirements placed on the final product become.

With The fiber-loading combination technology can be compared to the stand the technique a higher Freeness energiegünstig can be achieved, since up to 50% of the grinding energy can be saved; this has a positive influence on all types of paper in particular, undergo a grinding process in their preparation or one have high to very high freeness, such. B. FL cigarette papers, FL B & P papers, FL sack paper and FL filter paper. These are in particular FL cigarette papers with 100 to 25 CSF or 68 to 90 ° SR, FL-B & P papers with 600 to 50 CSF or 20 to 80 ° SR, FL sack kraft papers with 600 to 425 CSF or 20 to 30 ° SR and FL filter papers with 600 to 350 CSF or 20 to 35 ° SR.

The The high freeness achieved high mechanical skills of the final product have a positive effect on the production of FL cigarette papers, FL B & P papers FL sack paper and FL filter papers, as due to process-related mechanical loads in the different sections of the paper machine such as the press section, the dryer section and the area in which the fibrous web is rolled up, the intermediate produced and the final product to be produced by the use of winding, Umroll- and conversion machines is mechanically highly loaded. In particular, arise in the production of cigarette paper high mechanical loads on the used cigarette paper, partly due to the low basis weight and use be conditioned by winding machines.

By a better drying, d. H. to a residual moisture content of 1 to 20%, lets the efficiency for increase all paper types. A higher water retention capacity, d. H. 1 to 25%, gives a positive influence on the rewet, which is lower in the manufacturing process, as well as the printability the produced fibrous web. Another advantage for all paper types is the higher whiteness or the with up to 15 brightness points higher optical values, the in the production of all forms of paper and cardboard with or without white To emphasize cover layer. Through the use of fiber-loading technology are also the optical values, for example when using Deinking water, improved by up to 15 brightness points.

One Another advantage of Fiber Loading is the types of paper listed above in that for Special applications calendering is provided and this through the application of the fiber loading the so-called blackening (Black satin) by the incorporation of FL particles in, um and suppressed at the fiber and eliminated.

By the use of flue gas can be the carbon dioxide emissions reduce a paper mill by the carbon dioxide contained in the flue gas for the Fiber loading process is used. On the other side arises by the use of the carbon dioxide contained in the flue gas the advantage that transport and storage of liquefied carbon dioxide saved become.

advantageous embodiments The invention will become apparent from the dependent claims, the description and the drawing.

The according to an inventive Ver driving used flue gas, for example, has a carbon dioxide content between 2 and 30%. The flue gas can be cleaned prior to introduction into the fiber-loading process, for example with a washer, as described in the DE 101 20 637 A1 [Sections 0010 - 0011, scrubbing tower 14 in the single figure and related description].

From Advantage is when during charging or loading the pulp suspension with calcium carbonate a grinding energy in the range between 0.1 and 300 kWh per ton of fiber drought introduced becomes. Preferably, the loading and grinding can be done in separate and independent process steps one performed in an apparatus become.

According to one embodiment the invention is used as starting material aqueous pulp material, especially aqueous Fiber, from 0.1 to 20% consistency, preferably between 2 and 8% used.

According to the invention as filler preferably calcium hydroxide in the aqueous fibrous material, in particular the pulp, mixed, this being a solids content between 0.01 and 60%. According to the invention is also the use of a starting material other than calcium hydroxide or Calcium oxide to form the filler possible.

The Calcium hydroxide is passed through a static mixer or through a header tank admixed. Advantageously, the carbon dioxide in a moist pulp suspension with a preferred consistency of 0.1 to 60% according to the reaction parameters mixed. It falls Calcium carbonate in a carbon dioxide gas atmosphere.

According to the invention is simultaneously with the loading process (Fiber Loading) of the grinding process in an apparatus, the crystallizer; this is a grinding energy used, ranging between 0.1 and 300 kWh per ton of fiber dehydrated lies; Here is a short reaction time of the calcium hydroxide with important to carbon dioxide. The energy input, d. H. the amount of heat or the heating of the pulp suspension for the production of Crystals in various forms, is important to the invention.

When Starting material is used depending on the application of the respective reaction machine aqueous pulp with a fiber content between 0.01 and 60%.

In an advantageous embodiment of the method is provided that as a reactor, a static mixer, a refiner, a disperser and / or a fluffer FLPCC reactor is used, wherein the pulp content, in particular the Fiber content, with a static mixer between 0.01 and 15%; for a refiner (grinding machine) between 2 to 8% (low-consistency grinding) and between 20 to 35% (high consistency grinding) and one Disperser between 2 and 40% and a fluffer FLPCC reactor between 15 and 60%.

According to the invention, it is provided that the dilution water before, while or after the addition of carbon dioxide or calcium hydroxide or calcium oxide supplied becomes. It falls Calcium carbonate in the mixing of carbon dioxide in a calcium hydroxide solution or Suspension. The precipitation reaction Vice versa, the same happens when calcium hydroxide in less than one Carbon dioxide atmosphere standing Supplied with water becomes. It may be before, during or after the addition of carbon dioxide or calcium hydroxide dilution water be added.

With Advantage is for the precipitation reaction an energy input between 0.3 and 8 kWh / t used, in particular between 0.5 and 4 kWh / t if no grinding machine is used.

As well let yourself Provide that the process temperature between -15 and 120 C, in particular between 20 and 90 ° C, is.

According to the invention generate rhombohedral, scaleohedral and spherical crystals.

Advantageous the crystals have dimensions between 0.05 and 5 microns, in particular between 0.3 and 2.5 μm. Static and / or mobile, in particular rotating, Insert mixing elements. The method is advantageous in a printing area between 0 and 15 bar, in particular between 0 and 6 bar performed. there the pH is advantageously between 6 and 10, in particular between 6.5 and 8.5. Advantageously, the reaction time is between 0.05 seconds Minutes and 1 minute, especially between 0.05 and 10 seconds.

The The invention also relates to a device in which machines for loading the pulp suspension with calcium carbonate are present. These carbon dioxide-containing flue gas is supplied. The Machinery is a degassing system for removing excess gas downstream. The arrangement of the machines is basically off the above Documents known.

In a further development of the device is provided that the flue gas from a burn tion system, in particular a gas engine or a gas turbine, can be fed.

With Advantage includes the degassing a chest with a stirrer, a pressure sorter, a venting pump, a cyclone, a cleaner (high cyclone) and / or a deculator.

From Advantage is a development of the invention, in which the degassing arranged in the processing direction of the pulp suspension an intermediate chest is.

below the invention is in an embodiment closer by the single figure described. This shows a schematic view of a device for loading a pulp suspension.

A pulp suspension 1 (Figure) is in an arrangement not shown here in detail 2 supplied by machines for the fiber loading process. Likewise, the arrangement 2 also flue gas 3 from a storage container 4 via a gas pump 5 fed. The flue gas 3 comes for example from a power plant, an internal combustion engine, an internal combustion engine, a boiler or the like.

From the arrangement 2 becomes the pulp suspension 1 coming from the flue gas 3 Carbon dioxide has taken up to a degassing plant 6 forwarded in the pulp suspension 1 the carbon dioxide not absorbed by it and the non-recyclable residual gas are withdrawn. Subsequently, the pulp suspension 1 to an intermediate chest 7 forwarded. The intermediate chest 7 serves, for example, for intermediate storage of the pulp suspension 1 before it is forwarded to a headbox of a paper machine or other machine for making a fibrous web.

1

Fibrous suspension

2

arrangement

3

flue gas

4

reservoir

5

gas pump

6

degassing

7

Zwischenbütte

Claims (19)

Method for loading a pulp suspension ( 1 ) with cellulose fibers with calcium carbonate with the following process steps, introduction of calcium hydroxide in liquid or dry form or of calcium oxide into the pulp suspension ( 1 ), - introducing a carbon dioxide-containing flue gas ( 3 ) in the pulp suspension ( 1 ), - Precipitation of calcium carbonate by the in the flue gas ( 3 ) contained carbon dioxide and - removing excess flue gas ( 3 ) after the loading process. Method according to claim 1, characterized in that flue gas ( 3 ) containing between 2 and 30% of carbon dioxide in the pulp suspension ( 1 ) is introduced. A method according to claim 1 or 2, characterized in that a grinding energy is introduced in the range between 0.1 and 300 kWh per tonne fiber desiccant, wherein the loading and the grinding in an apparatus ( 42 ) be performed. Method according to one of claims 1 to 3, characterized in that aqueous starting material Fiber material, in particular aqueous fiber, of 0.1 to 20% consistency, preferably between 2 and 6% used becomes. A method according to claim 4, characterized in that the calcium hydroxide by a static mixer ( 16 ) or mixed through a receiver chest. Process according to one of Claims 1 to 5, characterized in that the reactor used is a static mixer, a refiner ( 80 ), a disperser and / or a fluffer-FLPCC reactor is used, wherein the pulp content, in particular the fiber content, in a static mixer between 0.01 and 15%; with a refiner and with a disperser between 2 and 40% and with a fluffer FLPCC reactor between 15 and 60%. Method according to one of claims 1 to 6, characterized that dilution water before, while or after the addition of carbon dioxide or calcium hydroxide or Calcium oxide is supplied. Method according to one of claims 1 to 7, characterized that for the precipitation reaction an energy input between 0.3 and 8 kWh / t, in particular between 0.5 and 4 kWh / t is used. Method according to one of claims 1 to 8, characterized that the process temperature between -15 and 120 ° C, in particular between 20 and 90 ° C, is. Method according to one of claims 1 to 9, characterized in that rhombohedral, scalenohedral and spherical crystals produced become. Method according to claim 10, characterized in that that the crystals dimensions between 0.05 and 5 microns, in particular between 0.3 and 2.5 μm, to have. Method according to one of claims 1 to 11, characterized in that static and / or movable, in particular rotating, mixing elements ( 68 ) are used. Method according to one of claims 1 to 12, characterized that it is in a pressure range between 0 and 15 bar, in particular between 0 and 6 bar, performed becomes. Method according to one of claims 1 to 13, characterized that it is at a pH between 6 and 10, in particular between 6.5 and 8.5, performed becomes. Method according to one of claims 1 to 14, characterized that the reaction time is between 0.05 seconds and 1 minute, in particular between 0.05 and 10 seconds. Device for carrying out a method according to one of Claims 1 to 15, characterized in that it comprises an arrangement ( 2 ) of machines for loading the pulp suspension ( 1 ) with calcium carbonate containing carbon dioxide-containing flue gas ( 3 ) and that the machines have a degassing system ( 6 ) is arranged downstream of the removal of excess gas. Apparatus according to claim 16, characterized in that the flue gas ( 3 ) from an incinerator, in particular a gas engine or a gas turbine, can be fed. Apparatus according to claim 16 or 17, characterized in that the degassing plant ( 6 ) comprises a chest with a stirrer, a pressure sorter, a venting pump, a cyclone, a cleaner (high cyclone) and / or a deculator. Device according to one of claims 16 to 18, characterized in that the degassing system ( 6 ) in the processing direction of the pulp suspension ( 1 ) an intermediate chest ( 7 ) is subordinate.