METHOD AND APPARATUS FOR REFINING LIGNOCELLULOSE-CONTAINING MATERIAL

Abstract: An apparatus for refining lignocellulose-containing material comprises a pressure-proof refiner housing (1, 40) with opposed refiner members (2, 3, 41, 42, 59, 60), which between themselves define a gap (8, 47). Liquid is supplied to the gap via radial passageways (12, 25, 26, 34, 50, 55, 56, 57) in a rotatable refiner member (2, 3, 42, 60), and the rotation of the refiner member brings about the desired pressure in the liquid, which pressure exceeds the pressure in the gap.

Description: Method and apparatus for refining lignocellulose-cont- aining material This invention relates to the refining of fibrous mater¬ ial, for example lignocellulose-containing material, in an apparatus comprising two opposed refiner members, at least one of which is rotatable, and which between them¬ selves form a gap for processing the lignocellulose-cont¬ aining material. Normally, the material is fed into the gap in the form of an aqueous dispersion, so that the material moves outward from within and is processed (refined) simult¬ aneously between the refiner members. During this process¬ ing great heat amounts develop, which can cause the water to evaporate. The reduction of water content caused hereby in the material can unfavourably affect the result of the refining process. When the .water content is too low, the material can be overheated locally and thereby be damaged and miscoloured. This applies especially to refiners with refiner members, which have a large extens¬ ion in radial direction, which in other respects is des¬ irable for intensifying the refining of the material. In order to overcome these- problems, it was found advant¬ ageous to maintain to the greatest possible extent the water content in the material while it is passing through the gap. The water content can be maintained by supplying water directly to the gap while the refining proces is going on. A remaining problem, however, is to establish an effect¬ ive control of the water supply, because it is very diff¬ icult to observe and record the conditions prevailing in the gap in respect of pressure, temperature and concentrat¬ ion. When liquid is supplied at the feed end of the gap, the first refining phase is to be carried out with too great an amount of water, as otherwise there would not be a sufficient liquid amount throughout the entire gap. Too much liquid at the beginning, however, results in too low a temperature and in inferior quality of the fibres refined. The present invention solves the aforesaid problem and at the same time provides a simple and reliable apparatus. As according to the invention the liquid is supplied through passageways in a rotating refiner member, a suit¬ able pressure in the liquid is obtained by the rotation of said member. This pressure is determined by the rot¬ ary speed of the refiner member and by the radial distance between the axis of rotation of the refining member and the opening of the passageway into the gap. This pressure must exceed the pressure in the gap. The liquid supply can thereby be controlled so that correct liquid amount and temperature are obtained in the gap. The fibre qual¬ ity is hereby improved, i.e. the fibres are longer and more fibrillated, and the shives content is reduced. The characterizing features of the invention become appar¬ ent from the attached claims. The invention is described in greater detail in the foll¬ owing, with refernce to the embodiments illustrated in the aceomp-aπyingdrawings, in which Fig. 1 is a cross- -section through a refiner housing comprising two count¬ er-rotating refiner members, Fig. ' 2 is a section along A-A in Fig. 1, Fig. 3 is a cross-section through a second embodiment comprising two counter-rotating refiner memb¬ ers, Fig. 4 is a cross-section through a further embodim¬ ent comprising counter-rotating refiner members, Fig. 5 is a section along A-A in Fig. 4, Figs. 6 arid 7 are cross- -sections through two further embodiments comprising counter-rotating refiner members, ig. " 8 is a section along A-A in Fig. 7, Fig. 9 is a cross-section through an embodiment comprising one stationary and one rotatable refiner member, Fig. 10 shows the . location of the liquid supply passageway at the embodiment shown in Fig. 9. Fig. 11 is a cross-sec-tion through another embodiment com¬ prising one stationary and one rotatable refiner member, Fig. 12 shows a further embodiment comprising one station¬ ary and one rotatable refiner member, Fig. 13 shows a nozzle for the supply of liquid to the gap between the refiner members, and Fig; 1*4 shows a detail of a refiner member where the nozzle is located. The embodiment shown in Fig. 1 comprises a pressure-proof refiner housing 1, in which a first and a second refiner member 2,3 rotatable in opposed directions are located. The members 2,3 are supported ' each on a rotary shaft 4,5 mounted outside the refiner housing 1. The refiner members 2,3 are provided on their surfaces facing toward each other with refiner disc segments 6,7, between which a gap 8 is formed. The first refiner member 2 is provided with apertures 9 for the supply of the material to be refined. In the refiner housing 1 a supply opening 10 is provided for feeding the material to the apertures 9- The second ref¬ iner member 3 is located on the shaft 5, . .which is axially movable for adjusting the gap 8. Outside the refiner memb¬ ers 2,3 an outlet 11 for the discharge of refined mater¬ ial from the refiner housing 1 is located. The first refiner member 2 is provided with a plurality of passageways 12 for liquid which extend from an axial passageway 13 in the centre of the shaft 4 radially outward in the refiner member 2 and open into the gap 8 at diff¬ erent radial distances from the centre. The liquid is supplied through a conduit 14 to the shaft 4 via a seal¬ ing box 15, which comprises an annular liquid chamber Iβ communicating with radial apertures 17 in the shaft 4. These apertures 17 lead ' inward to the axial passageway 13 in the centre of the shaft 4. The embodiment shown in Fig. 3 corresponds in principle to the first embodiment. Corresponding details have been given the same reference numerals. The liquid, however, is supplied through the second refiner member 3. Corresponding details have also in Fig. 4 the same refer¬ ence numerals as in Figs. 1 and 3- The shaft 5 is here providedwith four axial passageways 18,19, which are conn¬ ected to two separate liquid supply conduits 20,21. The liquid is transferred via a sealing box 15 having two annular liquid chambers 23,24, each of which communicates with two of the axial passageways 18 and, respectively, 19. The second refiner member 3 comprises radial passageways 25, β, which communicate with the axial passageways 18,19. The radial passageways 25,26 open into the gap 8 at diff¬ erent radial distances from the centre, so that liquid from the conduit 20 is supplied to the gap 8 through the passageways 25, and liquid from the conduit 21 is supplied to the gap through the passageways 26. In Fig. 6 corresponding details are designated as in Figs. 1, 3 and 4. Liquid is here supplied through a conduit 14 via a sealing box 15 to an axial passageway 27 in the centre of the axle 4. This axial passageway 27 is extend¬ ed by a pipe 28, which extends outward from the shaft end into a space 28 in the end portion of the opposed shaft 5. From this space 29 radial passageways 12 extend outward in the second refiner member 3. By this arrangement it is possible to supply liquid through the shaft 4, which is fixed in axial direction, while the liquid supply to the angled gap 8 still is possible from the inner refiner disc segment 7. The supply of liquid in this way can be advantageous, because the centrifugal force facilitates the penetration of the liquid into the material in the gap. The transfer of liquid from one shaft 4 to the other shaft 5 through the pipe 28 can give rise to a certain leakage from the space 29 outside .the pipe 28. This leak¬ age, however, is counteracted by the pump effect caused by the rotation of the refiner member 3. The liquid still leaking out in this way will flow outward to the gap 8 in the space between the refiner members 2,3 and thereby take along material, which may have been dislocated. In Figs. 7 and 8 an apparatus is shown where the liquid is supplied from the free end of the shaft 4. The shaft 4 is here provided with six axial passageways 30, which are connected in pairs to a device 31 for transferring liquid from conduits 32 to the shaft 4. The transfer dev¬ ice 31, like the aforesaid sealing boxes, comprises annul¬ ar liquid chambers 33, from which the liquid is led into the shaft 4. The radial passageways 3 in the refiner memb¬ er 2 open in pairs at different radial distances from the axis of rotation. According to this embodiment, these passageways 3 are provided behind the refiner dis.c segm-S ents 6 with pockets 35 intended to cool the refiner memb¬ er by means of the liquid supplied. The liquid is passed from the pockets 35 into the gap 8. The aforesaid embodiments can be combined in different ways, for example so that liquid is supplied to the gap from refiner disc segments on both sides of the gap. Figs. 9 and 10 -show an embodiment where a pressure-proof refiner housing 40 encloses a stationary refiner member 41 and a rotatable refiner member 42. The latter is att¬ ached on a rotary shaft 43, which extends outward from the refiner housing 40 and is supported outside thereof. A sealing box 44 is provided between the refiner housing and the shaft. On each refiner member 4l,42 refiner disc segments 45,46 are located, which between themselves def¬ ine a gap 47. The stationary refiner member 4l is formed with a central opening 48 for the supply of the material to be refined. The feed is ensured by a screw feeder 49. The rotatable refiner member 42 is axially movable in that the shaft 43 can be moved in axial direction. The refiner housing 40 is provided with an outlet 11 outside the refiner memb¬ ers 41,42. The rotatable refiner member 42 is provided with a plur¬ ality of passageways 0 for liquid. These passageways ex¬ tend from the centre of the shaft 43 radially outward in the refiner member and open into the gap 47 at different radial distances from the centre, as shown in Fig. 10. The liquid is supplied through the conduit 51 to an annul¬ ar liquid chamber 52 in the sealing box 44. This chamber 52 communicates with radial apertures 53 in the shaft 43 which lead inward to a central axial passageway 5 in the shaft. Said passageway 54 extends to the radial passageways 50. The embodiment according to Fig. 11 differs from Fig. 9 in that radial passageways 55,56,57, which open at diff¬ erent radial distances from the centre, are connected to separate conduits, in principle as shown in Figs. 4 and 5. The shaft 43 can be formed with six axial passageways 58, which are connected in pairs to each supply conduit, either via a sealing box 44 or from the end of the shaft 43. In Fig. 12 a variant of the invention is shown where a stationary refiner member 59 co-operates with a rotatable one 60, but where the gap 4 is formed with an inner radial portion and an outer angled portion. In other respects the embodiment agrees in principle with Fig. 9. Radial passageways 50 for liquid supply to the gap 47 open both into the radial portion of the gap and into the angledone thereof. In Fig. 13 is shown by way of example how the radial passageways 12 open into the gap 8. The first and, resp¬ ectively, the second refiner member 2 and, respectively, 3 are provided with refiner disc segments 6,7, the surface of which is formed with longitudinal members 6r,62 -for proces ing the material passing through the gap 8. For ensuring the processing between the members 6l,62, flow restrict¬ ions 63 are provided between the members 61 so that the material on its way out is forced upward from the grooves between the members 61. A nozzle 64- is connected to the passageway 12 so that its mouth 65 is directed in the flow direction of the material. The mouth portion of the nozzle 64 thus extends outward through the refiner disc segment 7 and constit¬ utes an integrated portion of the surface of the segment. The nozzle 64 is located in a bore 66 in the refiner memb¬ er 3 and retained in place by a bolt 67. The nozzle 64 communicates with the passageway 12 through a recess 68 extending all about,- which is surrounded by sealings 69. From said recess 68 a passageway 70 extends all the ' way to the mouth 65. The nozzle mouth, alternatively, can be directed across the gap 8. The liquid supply to the gap can be adjusted by varying the design of the nozzle 64 and the size of the passage¬ way 70. Different nozzles, thus, can be used for different diameters of the refiner member so that each portion of the gap is supplied with the desired amount of liquid. The liquid flow through the radial passageways in the refiner members can also be varied by adjusting the supply of liquid through the conduits. The aforedescribed nozzles can be used in all embodim¬ ents of the invention described above. It is also possible to imagine in the scope of the invent¬ ion idea embodiments other than those described above.

Claims: Claims 1. A method of refining lignocellulose-containing mat¬ erial, which is processed during its passage outward in a gap between two opposed refiner members, at least one of which is rotatable, at increased pressure and increas¬ ed temperature, and with liquid supplied to the gap, c h a r a c t e r i z e d i n that the liquid is supplied through one or more radial passageways in a rotating refiner member, and that the desired pressure in the liquid is effected by the rotation of the refiner member, and said pressure exceeds the pressure maintain¬ ed in the gap. 2. A method as defined in claim 1, c h-a r a c t e r - i z e d i n that the liquid is supplied to the gap in a plurality of positions at the same and/or at diff¬ erent radial distances from the axis of rotation of the refiner member. 3- A method as defined in claim 1, c h a r a c t e r ¬ i z e d i n that the liquid supply to the gap is adjustable. 4. A method as defined in claim 1, c h a r a c t e r ¬ i z e d i n that the liquid is supplied to the gap outward in the flow direction of the material. 5. An apparatus for refining lignocellulose-contain¬ ing material, comprising two opposed refiner members, at least one of which is rotatable, between which memb¬ ers a gap is formed, a pressure-proof refiner housing enclosing the refiner members, at least one opening located radially inside the gap in one of the refiner members for the supply of material to the gap, and a plurality of passageways for the supply of liquid to the gap, c h a r a c t e r i z e d i n that the liquid supply passageways are located in a rotatable refiner member and extends radially outward, so that the rotation of the refiner member brings about the desired, pressure in the liquid, which pressure exceeds the pressure maintained in the gap. 6. An apparatus as defined in claim 5, c h a r a c t ¬ e r i z e d i n that the radial passageways open in a plurality of positions at the same and/or different radial distances from the axis of rotation. 7. An apparatus as defined in claim 5, c h a r a c t ¬ e r i z e d i n that the radial passageways extend from one or several axial passageways in a shaft carrying the refiner member provided with radial passageways. 8. An apparatus as defined in claim 5, c h a r a c t ¬ e r i z e d i n that both refiner members are loc¬ ated on rotary shafts, and the radial passageways are located in one of said refiner members. 9. An apparatus as defined in claim 8, c h a r a c t ¬ e r i z e d i n that one rotary shaft is provided with a central axial passageway, which via a pipe passes over to the second rotary shaft, and the radial passage¬ ways are located in the refiner member located on said second shaft. 10. An apparstus as defined in claim 5, c h a r a c t ¬ e r i z e d i n that it comprises one rotatable and one stationary refiner member, and the radial passageways are located in the rotatable refiner member.

Inventors: SJOEBOM AXEL HENNING, SJOEBOM, AXEL, HENNING
Applicants: SUNDS DEFIBRATOR, SUNDS DEFIBRATOR AKTIEBOLAG
Application year: 1985
Main classification: D21B1
IPC codes: D21D1