EP1462566A2 - Method and apparatus for beating pulp - Google Patents

Abstract

To beat wood and other fiber materials, the material is passed between two beating surfaces, where the speed difference between them is between 5 m/second and 12 m/second or zero. The material is fed as a web (6) between two rotating rollers (2,3) in a beater (1), to be spread evenly over their beating surfaces. The rollers are rotated by motors (4,5).

Description

The invention relates to a method for grinding fibrous materials between two grinding surfaces and a device for performing of the procedure.

The best possible use of strength of all types of fiber (wood fiber, Annual plants, animal etc.) allows a more cost-effective Production of paper, leather, etc. To use this potential must be able to treat the fibers by means of a so-called grinding so that the binding properties of the fibers through appropriate measures come into play.

This process was traditionally large in so-called "Dutch" cylindrical, discontinuous machines. by virtue of lack of throughput and high specific energy consumption these machines were replaced by continuously working refiners.

At the moment refiners are in the form of the (double) disc, cone or of the cylinder. Disadvantages of the previous disc, cone or Cylinder types are the relative speed along the grinding zone that a relatively high "idle power" - depending on the type of grinding required. at particularly low throughputs can in turn depend on the type Problems with the centering of the rotor in the direction of attack occur.

Another significant disadvantage e.g. the cone refiner is the bad one Pump effect, as the centrifugal force does not act in the direction of the material flow. This results in throughput problems and, subsequently, the necessity enlarge the grooves, which reduces the edge length. The high forces occurring and the relative displacement of the knives when queuing, the need a robust design due to the occurring bearing forces and the difficult set change can be seen.

A cylinder refiner avoids many of these disadvantages but with an ordinary cylinder refiner, similar to the Cone refiner throughput problems to be expected. This can be done by using of a feed with integrated pressure build-up can be avoided.

Despite a significant reduction in idle energy consumption at Cylinder refiners - approx. 40 to 50% less - are compared to the Total energy input the strength potentials stored in the fiber materials unfortunately only insufficiently activated and in the manufacture of finished products used.

With the conventional grinding of fiber materials used up to now occur additional e.g. undesirable in paper production Phenomena - such as a sharp increase in drainage resistance, (Schopperrieglereinheit increase, loss of optical properties etc.). This reduces the production capacity on the one hand, on the other hand are significantly higher energy inputs for dewatering the Fiber webs as well as higher drying capacities are required.

In conventional grinding, the fibers are pumped in Low consistency range (<10%) or by means of screw conveyance, Displacement pumps or MC pumps in the medium and high consistency range (10%> k> 35%) between rapidly rotating grinding media from rotors and stators with differential speeds of approx. brought v = 15 to 70 m / s. The surface roughening and bruising of the fiber material requires these high differential speeds simultaneous pressing of the fiber. The majority of the brought in Energy is lost in frictional heat. According to literature sources only about 3 to 10% of the energy used for fiber treatment.

The present invention is intended to reduce or avoid the above disadvantages.

It is therefore characterized in that the differential speed the grinding surfaces are in the range of - 5 m / s and +12 m / s, whereby advantageous the differential speed is almost zero. This allows a great economic advantage by reducing the idle power by achieve up to 90%. The low differential speed also allows a targeted application of pressure forces on the single fiber or Fiber composite whereby crushed grinding is achieved. The big ones technological advantages of crushed grinding were already included the use of the first ramming machines, but never could be integrated industrially in continuous process stages.

An advantageous development of the invention is characterized in that that the pulp is fed to the grinding in the form of a pulp web becomes. This has the advantage that very high capacities in one uniform process step already at the end of the pulp manufacturing process on the one hand, inexpensive and technologically targeted pre-grinding can be. This allows for further processing of the Fiber in conventional stock preparation systems a clear Reduction of the necessary grinding effort. Extensions of the grinding plants or improvements to achieve the grinding systems higher strengths can be eliminated.

According to a further variant of the invention, two or more Meals carried out in succession. The advantage of a serial Circuit is in an increased use of the existing fiber strength potential to see.

A favorable embodiment of the invention is characterized in that that the pulp is evenly distributed over the grinding zone. The size created surface paired with a great uniformity of Fiber distribution in both cross and longitudinal and Z direction leads to a high fiber hit probability with the advantage of a uniform Fiber treatment using the strength potential if possible many single fibers, i.e. the overall strength level can are used to a particularly large extent.

According to an advantageous development of the invention, the fibrous material fed directly from a thickening machine to the grinding machine. The technical and economic advantages are similar to those already mentioned. On top of that, the investment is due to the elimination of large laid paper, pipes, pumps, measurement and control technology is reduced and therefore the process can be made simpler.

The invention also relates to a device for carrying out the Process. It is characterized in that rollers are used as grinding media are provided. The advantage is continuous operation.

This is a particularly advantageous embodiment of the invention characterized that the rollers are driven at the same speed will / have the same speed. The advantage is one very little effort for friction force with intensive application of adjustable press forces. The low frictional force triggered by the almost nonexistent relative speed reduces the energy requirement for rail transport and crushing to almost zero.

According to a favorable further development of the invention, pairs of rollers are included wide grinding gap provided, the roller (s) for generating the wide grinding gap, a shoe support or a beam support can have. Due to the wide grinding gap design the forces on the one hand gentle intervention with simultaneous Extension of the dwell time. A favorable embodiment of the invention is characterized in that the rollers have spikes. The Spikes increase the "clothing surface" and enable a better one Penetration and treatment of the fiber material.

An advantageous development of the invention is characterized in that that the rollers have grooves or grooves, the grooves or Grooves run in the circumferential direction or at an angle to the roller axis can. The increase of the roller surface by means of scoring, grooving etc. brings the advantage that the number of reached and thus treated individual fibers is enlarged.

An advantageous embodiment of the invention is characterized in that that the grooves or grooves interlock. Is due to the design interlocking possible - positive locking - there is no Differential speed. The total energy expenditure is reduced or implemented in a kind of press grinding. This leads to a maximum Use of raw materials with regard to the development of strength with the least possible Increase in drainage resistance.

According to a favorable embodiment of the invention, the grooves or grooves are trapezoidal
According to an advantageous development of the invention, the bottom of the grooves or grooves can have drainage depressions. Residual water - for example with low inlet material densities - escapes into the wells and can be sucked out or spun out of these wells. This has the advantage that higher solid concentrations occur in the grinding zone. Depending on the process control, a necessary process step can be omitted or higher final dry contents can be achieved. This means that the energy required for a subsequent thickening stage or thermal drying can be reduced.

A favorable embodiment of the invention is characterized in that that the rollers have a drive.

According to an advantageous embodiment of the invention, the material is fed by means of its own web guide up to just before the grinding zone, whereby there is no need for pre-assemblies. The advantage lies in a reduction of investment costs and space requirements.

It has proven to be advantageous if the fibrous material comes directly from a thickening machine the grinder is fed, since this is an additional Machine for an even web-like distribution of the fiber material can be dispensed with.

In an advantageous embodiment of the invention is a moving Wire, rubber or the like -braid provided, this at least one Roll encloses or guided over deflection rollers and at least one Roller can be pressed.

The invention will now be described by way of example with reference to the drawings, Fig. 1 is a schematic representation of the invention, Fig. 2 is a schematic side view of a variant of the invention, Fig. 3 is a schematic side view of a further variant of the invention, FIG. 4 2 shows a schematic side view of a next variant of the invention, 5 shows an embodiment of the invention, FIGS. 6 and 7 show further variants represent the invention.

Roll speed, roll gap length, roll distance, differential speed, Contact pressure, surface structure and material properties determine the time of action of the grinding force on the regrind. The machines shown in the pictures look similar to one Press concept on a paper machine. Also for grinding applications can the basic principle of a so-called "Extended Refining's" or

Extended Retention Refinings (ERR) are used, whereby the Exposure time / meal can be increased many times.

One or more rollers can be used to increase the grinding effect (Nips) can be arranged in series. This illustrated Instructions apply to both low and high consistency grinding.

In addition to large ones, a large grinding gap is suitable for producing Roller diameters, any kind of shoe or beam support. Several of these wide nips can be produced in series and at short intervals consequences. These rollers can also improve and increase the Grinding uniformity is a flexible, pneumatic, hydraulic bearing Use substructure. The carrying shoe can be guided with support bodies that are used to support lubrication openings such as Bores, sintered metals used for the passage of the lubricant (Water, air, oil, etc.).

Essential for the novel treatment of fiber materials to increase the strength properties by using the in The potential of the fibers is the design of the roller surface. This can be smooth on one or two sides, with spikes or with wave-like grooves are provided. These grooves, gullies can be in the circumferential direction (see Fig.) or at an angle to across run to the roll axis direction.

The rollers have circumferential grooves that interlock. The depths of the Scoring is based on the type of fiber, the web fleece thickness and the Solids content selected. Trapezoidal depressions are also advantageous a groove depth of 1 to 25 mm. The groove bottom can be used with drainage depressions - e.g. additional holes for water drainage similar a suction roll principle in a press section of a paper machine be provided.

The grooves can be milled, ground, etched into the roller body, eroded or raised. A simple raised groove design, which differ due to the selected wire shape Allowing geometries can be done by winding.

Instead of a second pressure roller, a rotating wire, Rubber etc. braid enclose the roller body and by means of additional pressure for a long-term crushing. For maximum fiber crush due to the low contact pressure mainly rollers with smaller diameters are used.

Alternatively, one can be made from a wire or rubber braid existing tape can be pressed against the roller or over extend several rollers.

The roller circumferential speed - or a possibly set one Differential speed - also depends on the Roll surface.

For setting the speeds - any small differential speeds - The rollers are driven.

Rollers, the grooves and elevations in turn out to be of great advantage have a regular circumferential distance, similar to that Corrugated rollers in shaft production.

These grooves run parallel or at an angle of 0 ° to 45 ° to the Roller axis (helical teeth): They can be interrupted in the circumferential direction be what a short term especially at low substance concentrations and allows easy drainage. This favors the grinding.

The flank design of the grooves can in turn be small so-called Show signatures.

Since the grinding treatment is based on an intensive crushing, are also suitable grinding media basic structures similar to a perforated roller. In the case of a surface structure provided with holes, there is an additional one Drainage process during the grinding process. The holes can be carried out as blind bores, among other things.

Other variants are surface finishes, such as these at Grinders can be used. In this case, since there is no meshing the grinding media takes place, the rollers can be adjusted operated at different speeds. So that Ratio between shear and pressure can be varied.

The surfaces themselves are made from very hard material to get long downtimes.

The grinding elements on the roller body can be attached in segments will be or also individual and insertable elements that be made from high quality steel or ceramic.

For reasons of wear and tear, steel alloys will become like at present Refiners used, are suitable. All materials can also be surface-alloyed become.

Different materials can be used for special applications Pressure rollers can be used in combination.

The use of materials with different degrees of hardness or Material allows the grinding zone to be enlarged, which in turn increases the targeted crushing is favored.

With this machine concept, the idle drive power drops to approx. 3 - 5% of conventional grinding plants, the total energy requirement for Achieving the same strengths below 50%. In addition, opacity remains and other optical properties compared to the conventional one Better grind.

The capacity of these grinders is a function of the working width and the mass per unit area of the preceding distributor. The Working widths of the grinding machines can be easily specified Adjust production by changing the material distribution width.

The untreated web introduced into the grinding gap has a weight of 100 to 1500 g / m ² in most cases. This applies to LC (low consistency) as well as MC (middle consistency) and HC (high consistency) grinding. The mass per unit area can be adapted to the respective raw material.

There are basically two machine types in terms of consistency possible.

In the case of a feed in the low consistency area, the material is fed to the Grinding zone by means of its own path guidance, which runs until immediately before the grinding zone is sufficient. The goal is an even distribution of the regrind to get into the grinding zone. The fabric is not thickened, but could be brought to a higher consistency, especially only evenly distributed over the grinding zone.

Advantageously, e.g. grinding of waste paper carried out directly after a thickening machine. The one to be treated Fibers can be fed directly from the thickening machine to the grinding machine become. This is especially true when treating fabrics with higher ones Consistencies.

As soon as higher consistencies due to the already improved initials With this type of Grinding treatment spoken of high consistency grinding. The The range of consistency can vary very widely (advantageously 25% to 65% dry content - limitation only through mechanical drainage), and is essentially from the raw material, the area-related Mass of the fiber web and its pretreatment dependent. Hardwood, Recycled grades require a higher consistency than softwood - Fibers.

As in the case of low consistency grinding, the pulp is Guided and in this by targeted pressing of the rollers and

Control of the roller speeds primarily pinched. in this connection the inner and outer surface is enlarged and bond activated.

With this method it is essential that the grinding zone is even is filled so that the fiber material has the same treatment over the Receives web width.

The roller surfaces are similar to those in the case of low consistency grinding embossed, corrugated, spiked, can be a groove - Corrugated profile - similar to corrugated cardboard corrugation, etc.

Fig. 1 shows schematically a device according to the invention. The grinder 1 here consists of a roller 2 and a roller 3, which means Motor 4 and 5 are driven. The drive is preferably carried out with same speed, so that the regrind, here in the form of a track 6, only press but not subjected to shear forces.

2 shows a variant of the invention in a side view. The Rolls 2 and 3 of the grinding plant 1 are shown here with spikes However, corresponding grooves or grooves can also be provided his. Both rollers are pressed against each other. The unground Fibrous material is used by means of suitable belts 8 and 9 immediately before Grinding gap 7 introduced between the rollers 2 and 3 and evenly distributed over the grinding zone.

FIG. 3 shows a plant analogous to FIG. 2. However, there are two grinding devices here 1, 1 'with grinding rollers 2, 3 or 2', 3 'arranged one behind the other.

Fig. 4 shows an embodiment with a so-called central grinding roller 10, which has to absorb the forces of the other two rollers 11, 12. The advantage of such an arrangement is a compact design. at This configuration allows all rollers to have the same surface speed operate. Depending on the quality requirements of the The two outer rollers can be finished, however, different Press pressures, surface equipment and / or various, adjustable Have relative speeds.

Fig. 5 shows a variant of the invention, in which a moving wire, Rubber or the like -braid 13 encloses the roller 2. This allows a long-term crushing of the fiber can be achieved.

A further variant of the invention is shown in FIG moving wire, rubber or the like -braid 13 'is provided, the over Deflection rollers 14, 14 'is guided. The wrap α of the roller 2 can be from 0 ° (point pressure) to approx. 350 °.

The variant shown in Fig. 7 shows a moving wire, rubber or the like. -braid 13 ', which is guided over deflection rollers 14, 14' and against several rollers 2, 2 ', 2 ", 2"' is pressed. The pressure is applied on the one hand between the deflection rollers 14, 14 'and the end rollers 2, 2 "' and with the help of a support body 15 against the rollers 2 ', 2 ".

Claims (26)

Process for grinding fibrous materials between two grinding surfaces, characterized in that the difference in speed of the grinding surfaces is in the range from -5 m / s and +12 m / s. A method according to claim 1, characterized in that the differential speed is almost zero. A method according to claim 1 or 2, characterized in that the fibrous material is fed to the grinding in the form of a web. Method according to one of claims 1 to 3, characterized in that two or more grindings are carried out in succession. Method according to one of claims 1 to 4, characterized in that the fibrous material is distributed evenly over the grinding zone. Method according to one of claims 1 to 5, characterized in that the fibrous material is fed directly from a thickening machine to the grinding machine. Device for grinding fibrous materials between two grinding surfaces, characterized in that rollers (2, 3, 2 ', 3', 10, 11, 12) are provided as grinding bodies. Apparatus according to claim 7, characterized in that the rollers (2,3,2 ', 3') are driven at the same speed. Apparatus according to claim 7 or 8, characterized in that the rollers (2,3,2 ', 3', 10,11,12) are operated at the same surface speed. Device according to one of claims 7 to 9, characterized in that the rollers (2,3,2 ', 3', 10,11,12) are operated at the same surface speed but have different speeds Device according to one of claims 7 to 10, characterized in that pairs of rollers (2, 3 or 2 ', 3') are provided with a wide grinding gap. Apparatus according to claim 11, characterized in that the roller (s) for generating the wide grinding gap has or have a shoe support. Apparatus according to claim 11, characterized in that the roller (s) for generating the wide grinding gap has or have a beam support. Device according to one of claims 7 to 13, characterized in that the rollers (2,3,2 ', 3', 10,11,12) have spikes. Device according to one of claims 7 to 13, characterized in that the rollers (2,3,2 ', 3', 10,11,12) have grooves or grooves. Apparatus according to claim 15, characterized in that the grooves or grooves run in the circumferential direction. Apparatus according to claim 16, characterized in that the grooves or grooves run at an angle to the roller axis. Device according to one of claims 15 to 17, characterized in that the grooves or grooves interlock. Device according to one of claims 15 to 18, characterized in that the grooves or grooves are trapezoidal. Device according to one of claims 15 to 19, characterized in that the bottom of the grooves or grooves has drainage depressions. Device according to one of claims 7 to 20, characterized in that the roller surface has a predetermined roughness. Device according to one of claims 7 to 21, characterized in that the material is fed by means of its own web guide (8, 9) up to immediately before the grinding zone (7). Device according to one of claims 7 to 22, characterized in that the fibrous material is fed directly from a thickening machine to the grinding machine. Device according to one of claims 7 to 23, characterized in that a moving wire, rubber or the like. -braid (13, 13 ') is provided. Device according to claim 24, characterized in that the moving wire, rubber or the like. -braid (13, 13 ') encloses at least one roller (2). Device according to claim 24, characterized in that the moving wire, rubber or the like. -braid (13, 13 ') guided over deflecting rollers (14, 14') and pressed onto at least one roller (2, 2 ', 2 ", 2"').

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