Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
  • D21B1/00—Fibrous raw materials or their mechanical treatment
  • D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
  • D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
  • D21B1/30—Defibrating by other means
  • D21B1/34—Kneading or mixing; Pulpers
  • D21B1/345—Pulpers
  • D21B1/347—Rotor assemblies

Definitions

• IMPROVED IMPELLER FOR PAPER PULPS KNEADERS This invention is about an impeller for paper pulps kneaders.
• kneaders are used for the making of paper pulps, which basically consist of a container wherein an impeller is placed that carries out the making of the pulp by chipping wastepaper into an aqueous bath.
• the action carried out by the kneader allows separating the cellulose fibres and making homogenous the water suspension of the same fibres. Another important function of the kneader is that of separating the ink which soaks the cellulose fibres' paper so as to remake new paper free of ink contamination.
• the impeller of the kneader has a frustum conical shape with the major base placed on the bottom of the tank and it is equipped with a number of blades cross-wound around a central vertical shaft which determines a longitudinal spin axis.
• the impeller acts essentially as a pump which conveys the paper pulp towards the bottom through the channels formed between the blades and then makes it ascend continuously from the bottom upward along the walls of the tank, thus carrying out the pulping action.
• the separation of the pulp from the ink takes place because of the rubbing among the fibres.
• the state of the art impellers are of the multi-start type, and they are usually equipped with three blades, like, for example, the state of the art kneader which is described in the patent EP 0 775 233 registered under the name of the same applicant of this patent.
• the kneader's impeller of the previously mentioned patent is exactly of the triple-start type, it has a frustum conical shape, and has a convergent taper towards the upper part of the tank which contains it. It must also be noticed that in the ending section of the blades there is a toothing having the function of promoting the tearing of the thicker parts of the mixture, such as cardboard for example, mostly in the pulping starting phase.
• the inconvenience that the impeller described in the abovementioned patent has, consists in that the toothing placed on the edge of the ending section of the blades is turned upwards and therefore is not able to develop an optimal tearing of the product to be treated.
• an impeller for paper pulps kneaders that in line with the main claim, it comprises:
• each of said blades has an ending section, connected to said bottom flange, where there is a toothing on its peripheral edge, said toothing being delimited between the following: - a first point that corresponds to the intersection between the peripheral edge of said blade and said peripheral edge of said ending section;
• the toothing being placed slanted and at the end of each blade, gets in contact with the entire mixture flow exiting from the channels among the blades and is thus able to carry out, compared to the state of the art impellers, a greater pulping level of the under treatment product.
• the presence of a directional member improves the radial flow of the product exiting from the impeller in proximity of the bottom and the axial flow during the subsequent ascent along the tank's walls.
• FIG. 1 shows an isometric view of an embodiment of the impeller of the invention
• FIG. 2 shows an isometric view of an operative embodiment of the impeller of the invention.
• the impeller of the invention is shown through an isometric view in figures 1 and 2, where is generally indicated with 1.
• the impeller comprises an essentially plan bottom flange 2, connectable to driving means equipped with a central shaft 4 which starts from the plane K defined by the bottom flange 2 and where blades 5 are cross- wound around it.
• the connection of the bottom flange 2 to the driving means takes place through screws which are coupled with through holes 3.
• the central shaft 4 determines the longitudinal spin axis X of the impeller 1 which, in the case here described, has a frustum conical shape with the major base placed in the lower part and thus in proximity of the bottom of the container that holds it and that here is not shown. Furthermore the impeller 1 is of the three-start type and thus is comprised of three blades.
• connection of the impeller 1 to the driving means can also take place through different screw systems, in which case the bottom flange 2 will be free of holes 3.
• the number of starts of the blades which make up the impeller can vary as a function of the different user's needs.
• each of said blades 5 has an ending section 6 connected to the bottom flange 2, where there is a toothing 7 on its peripheral edge 6a, which is delimited between the following: - a first point 8 that corresponds to the intersection between the peripheral edge 5a of the blade 5 and the peripheral edge 6a of the ending section 6 that as it is shown they have different inclinations among them;
• the toothing 7 involves the ending section of each channel 10 defined between each pair of blades 5 and therefore goes to involve all the under treatment material every time it flows through the same channel 10 during the rotation of the impeller.
• the toothing 7 being slanted with respect to the plane K of the bottom flange 2, always involves the entire mixture's flow and hence not only in the initial phase of the treatment as it occurs for the state of the art impellers wherein the toothing is placed on the peripheral edge 5a of each blade 5 and is turned upwards.
• the impeller comprises a directional member 11 which radially protrudes from the impeller 1 and it is developed along the peripheral edge 5a of each blade 5 starting from the first point 8.
• the directional member 11 is developed for a stretch of the axial pitch of each matching blade 5 which, preferably but not necessarily, corresponds to one fourth of the same pitch.
• the presence of the directional member 11 facilitates the radial outlet of the mixture from the channels between the blades and its subsequent ascent along the tank's walls.
• the mixture is greatly involved by the pulping action induced by the rotation of the impeller.
• the front comer 11a of said directional member 11 is radially arranged parallel to said plane K and its extension passes through said longitudinal axis X.
• a plane ⁇ is defined which passes through the longitudinal axis X of the impeller 1 and through the first point 8 and that it determines a direction 12 on the outer surface 5b of each blade 5.
• This direction by intersecting the longitudinal axis X, forms a ⁇ angle which further improves the effect generated by the presence of the directional members 11.
• the ending section 6 of each blade 5 turns out to be more outward slanted and thus it contributes, together with the pressure of the directional member 11 , to improve the mixture's radial flow exiting from the channels among the blades close to the bottom.
• the ascent of the mixture along the walls of the container which holds it is also facilitated.
• the impeller of the invention shown in figure 1 rotates in the clockwise direction indicated by the arrow 13.
• the invented impeller achieves the preset objects in both illustrated and described embodiments.
• some modifications suitable for improving its operation or for making its construction cheaper can be carried out.
• the impeller of the invention can be made by using any size, with any number of starts, and with blades having whatever inclination.

Landscapes

• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Mechanical Engineering (AREA)
• Paper (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=29561060

Family Applications (1)

Country Status (4)

Family Cites Families (2)

• 2002
  • 2002-05-27 IT ITVI20020110 patent/ITVI20020110A1/it unknown
• 2003
  • 2003-05-23 WO PCT/EP2003/005409 patent/WO2003100165A1/en not_active Application Discontinuation
  • 2003-05-23 EP EP03755116A patent/EP1511897A1/de not_active Withdrawn
  • 2003-05-23 AU AU2003250330A patent/AU2003250330A1/en not_active Abandoned

Non-Patent Citations (1)

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