Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
  • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
  • D21D5/02—Straining or screening the pulp
  • D21D5/023—Stationary screen-drums
  • D21D5/026—Stationary screen-drums with rotating cleaning foils

Definitions

• the present invention relates to the problems of filtration of pulp and more particularly of pulp from the pulping of waste paper.
• filters comprising a rotor and a stator, one of the two, hereinafter called a screen fulfilling the filtering function comprising holes such as slots or holes, the other hereinafter called unclogger, fulfilling the unclogging function comprising means intended to generate pressure pulsations to prevent clogging of the bores.
• the screen can therefore be fixed or rotating and, conversely, the decolmator is rotating with a fixed screen and, fixed with a rotating screen.
• the liquid can either flow through the screen from the outside to the inside (towards the axis), so-called centripetal operation, or from the inside to the outside, so-called centrifugal operation.
• the dough arrives at one end of the cylindrical sieve, flows into the space between the cylindrical sieve and the decolmator, and exits at the other end.
• the decolmator turns, it tends to drag the dough with it in rotation. If the decolmator is fixed, it is the filter which tends to drive the dough in rotation. In both cases, as the effect of unclogging by the pressure pulses caused by the unclogging device is directly linked to the speed difference between the decolmator and the dough, the more the dough progresses towards the end of the sieve, the less effective the unclogging and this while the sieve is more prone to clogging.
• the long fibers have a harder time passing than the short fibers and therefore the proportion of long fibers compared to short fibers increases as the dough progresses, which accelerates both the flocculation process and the clogging process.
• the zone of strong deflocculation can be a zone of violent agitation arranged at the entry of the sieve;
• the present invention relates to a filtration apparatus or purifier of the type comprising a screen of cylindrical shape and a coaxial rotor provided with blades which produce pressure fluctuations to prevent clogging of said screen; said screen and said rotor comprising at least two parts, of substantially equivalent diameter, these parts being separated from each other by means intended to break the component of the speed of the liquid, which is parallel to the surface of the screen, and creating turbulence, characterized by the fact that said means are baffles constituted on the one hand by cavities arranged between the parts of the screen, the bottom of said cavities being possibly further from the rotor than the surface of the screen; and, on the other hand by annular deflectors carried by the rotor opposite each cavity; so that the majority of the liquid flow is forced to pass through the cavities.
• the present invention may also comprise all or part of the following arrangements, taken together or separately: a - the sieve consists of a stack of rings, b - the sieve consists of a grid obtained by juxtaposition of bars, sometimes called wires, which are either parallel to the axis of rotation of the rotor, either perpendicular or inclined, c - the screen consists of a juxtaposition of grids as described in the previous paragraph, these grids being separated by crowns, d - the sieve consists of a perforated cylindrical sheet plate, with holes or slits, e - the sieve consists of a stack of perforated cylindrical sheets with holes or slits, f - the cavities are hollow parallelepiped volumes, g - the cavities are hollow cylindrical volumes, h - some cavities can be connected at their bottom to a dilution inlet which can be ensured by water or less designed paste less than the filtered dough.
• the present invention also relates to the use of this device with regulating means allowing: a) either to adjust the speed of the rotor as a function of the pressure differential of the dough between the inlet of the device and one at less outlets accepted; b) either to adjust the rotor speed as a function of the flow rate (s) in at least one of the accepted product outlets; c) either by adjusting the rejection outlet flow rate of the apparatus as a function of the accepted flow rates and of the dilution flow rates measured to adjust the rejection rate of one or more parts of the screen; d) or by combining two or three of these means of regulation.
• the present invention also relates to the implementation of the means described above for the filtration of paper pulp.
• Figure 1 a first embodiment according to the invention comprising fins providing an area of strong deflocculation.
• Figure 2 a second embodiment comprising a slowdown zone obtained by means of baffles.
• Figure 3 a sectional view along AA of Figure 2.
• Figure 4 an alternative embodiment of Figure 2.
• Figure 5 a second alternative embodiment of Figure 2.
• Figure 7 a fourth embodiment using the slowing means of Figure 2, in a centripetal filter.
• Figure 8 a perspective view illustrating a sieve according to the invention.
• FIG. 9 a perspective view illustrating the rotor intended to be placed inside the screen of FIG. 8.
• Figure 10 a partial perspective view showing the interior of the screen of Figure 8.
• Figures 11 and 12 two partial and large-scale views of Figure 10.
• Figure 13 a partial view of the interior of an alternative embodiment of the screen of Figures 8, 10, 11 and 12.
• Figure 14 a partial view of an alternative embodiment of a filter element according to the invention.
• Figure 15 a partial view of another alternative embodiment of a filter element screen according to the invention.
• Figure 16 a vertical sectional view of a filter element according to the invention.
• Figure 17 an exemplary embodiment of a filtration apparatus.
• the sieve is constituted, as described in patent EP 0 707 109 by a stack of circles 1 of U-section, pressed against each other by means of two end rings 2 and 3 assembled to one another by tie rods 4 which make it possible to establish a prestress.
• the bases of the U are provided with holes (whether slits or holes).
• the dough arrives in the filter through its end located on the left of the figure (on the side of the crown 2) and emerges through its opposite end (on the side of the crown 3) by circulating in the space 6 located between the decolmator 5 and the sieve as indicated by the arrow fl.
• turbulence is created by fins 10 fixed on the decolmator and fins 11 fixed on the screen.
• These fins 10 and 11 may be radial or inclined and may have inclinations in the opposite direction.
• the shapes of the fins 10/11 are such that they overlap one another.
• a series of baffles are placed in the sieve which slow down the rotary movement of the dough.
• one or more circles 1 are replaced by a plurality of partitions 20, parallel to the axis of the filter which, with the edges of the two rings 1 which surround it, constitute a plurality of parallelepipedic cavities. C arranged around the entire circumference of the sieve.
• annular partition 21 is arranged perpendicular to the axis of the filter and carried by the rotor 5.
• the flow of dough is deflected by the annular partition 21 and strikes the partitions 20 which are linked to the sieve and crosses the cavities C to return to the space 6.
• Fluidization is understood to mean an agitated and flock-free state of the dough which promotes flow in the openings, holes or slots of the sieve.
• the screen is divided into two parts; a first part upstream of the crown of cavities C and a second part downstream, these two parts being separated from each other by the crown of cavities C.
• the baffle 20/21 is arranged in the middle of the screen; in Figure 4 it is arranged near the end, that is to say where the clogging effects are greatest due to the thickening of the dough.
• Figure 5 combines the provisions of Figures 2 and 4.
• Figure 6 combines the provisions of Figures 1 and 2.
• FIG. 7 represents a centripetal filter which uses the means of FIG. 2. The same elements have the same references.
• the sieve 1 is located inside the decolmator 5.
• the dough arrives through the end of the sieve and circulates in the space 6 located between the sieve 1 and the decolmator 5.
• the dough is deflected by the annular partition 21 and strikes the partitions 20.
• Figures 8 to 18 show an alternative embodiment of 'the apparatus implementing the method according to the present invention.
• Figure 8 shows a cylindrical screen 30 which consists of bars 31 arranged vertically next to each other with a slight clearance (between 0.05 mm and 1 mm) and fixed on horizontal rings 32, 33, 34, 35, 36 and 37. These rings 32 to 37 are crossed by tie rods 38, parallel to the axis of the cylinder, these tie rods 38 being fixed to the two end rings 32 and 37, so that the assembly is held by tightening the tie rods 38.
• FIG. 9 shows the rotor 40 which is placed inside the sieve of FIG. 8.
• This rotor is a cylinder which has three annular rings 41, 42, and 43. In the areas between the annular rings are arranged blades 45, usually called “foils" in the pulp industry.
• the foils 45 have the function of causing pressure / vacuum pulsations which tend to prevent clogging of the screen.
• the rings 41 to 43 are arranged on the rotor so as to be opposite the rings 33, 34 and 35.
• the annular rings 41, 42 and 43 define four zones of the rotor 40.
• the shape, number and inclination of the blades or foils 45 can vary from one zone to another.
• Figure 10 shows the screen of Figure 8 seen from the inside.
• crowns 33, 34 and 35 are hollow so as to define cavities C.
• the cavities C are not made as in the case of FIGS. 1 to 7 where the screen was made up of U.
• the crowns 33, 34, 35 are constituted by a ring comprising a multitude of parallelepipedic cavities having practically the same shape as the cavities C of FIGS. 1 to 7.
• Certain cavities C of the crowns 33 and / or 34 further comprise orifices which are connected to conduits 50 for dilution arrival.
• FIGS. 11 and 12 are detailed views, on a larger scale of FIG. 10.
• FIG. 13 illustrates a variant according to which, instead of having the parallelepipedic cavities C, there are cylindrical cavities or blind holes D, some of which can be connected to conduits 50.
• the annular ring of the rotor 41 (42,43) which cooperates with the ring 33 (34, 35) is arranged so as to to be practically at the middle of the cavities C or cylindrical holes D.
• the arrow F illustrates how dough coming from the zone located below the crowns 33, 41 is forced to enter a cavity C or D, this cavity and the crown 41 forming a baffle which considerably slows down the speed of the dough.
• FIG. 15 illustrates another alternative embodiment in which the same elements have the same references.
• the screen 30 is fixed and placed outside the rotor 40 which carries foils 45.
• the ring 41 of the rotor 40 is opposite the ring 33 of the screen 30 so that the cavities C of said ring 33 form with the annular crown 41 a series of baffles.
• a pipe 50 which is a water pipe.
• the filtration element according to the invention can comprise, from top to bottom:
• the filter element constituted by the screen 30 and the rotor 40 is thus divided into three zones X, Y and Z starting from the bottom.
• the dough to be cleaned arrives at Q at the base of the device.
• Zone X has an outlet 60 for so-called “accepted” products, that is to say products which have passed through the screen 30; zone Y has an outlet 61 for accepted products and zone Z an outlet 62 for accepted products.
• the device has a cover 63, an outlet R for discharges.
• the speed of the rotor 40 can be adjusted as a function of the pressure differential between the inlet Q into the apparatus and at least one of the pressures prevailing in the outlet conduits for the accepted products 60, 61, 62. It is also possible to adjust the speed of the rotor 40 as a function of one or more of the flow rates in the pipes 60, 61 or 62.
• the sieve can be produced in many ways either by stacking U-shaped rings of FIGS. 1 to 7, or by stacking grids obtained by juxtaposition of bars in FIGS. 13 and 14, or by stacking perforated cylindrical sheets or with slots of figure 16.
• they can be constituted by plates 70, in the mass of which grooves 71 have been dug with circular cutters, the slots then being machined with circular saws.
• edges of the cavities C or D are exactly at the same level as that of the internal wall of the screen 30.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Paper (AREA)
• Filtering Materials (AREA)
• Combined Means For Separation Of Solids (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Centrifugal Separators (AREA)
• Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)

Priority Applications (9)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9542587

Family Applications (1)

Country Status (12)

Cited By (5)

Families Citing this family (10)

Citations (4)

Family Cites Families (9)

• 1999
  • 1999-02-26 FR FR9902425A patent/FR2790270B1/fr not_active Expired - Lifetime
• 2000
  • 2000-02-25 BR BRPI0007868-9A patent/BR0007868B1/pt not_active IP Right Cessation
  • 2000-02-25 ES ES00907721T patent/ES2218131T3/es not_active Expired - Lifetime
  • 2000-02-25 CA CA002362500A patent/CA2362500C/fr not_active Expired - Fee Related
  • 2000-02-25 WO PCT/FR2000/000468 patent/WO2000050690A1/fr not_active Ceased
  • 2000-02-25 US US09/890,787 patent/US6679384B1/en not_active Expired - Lifetime
  • 2000-02-25 JP JP2000601244A patent/JP4530545B2/ja not_active Expired - Fee Related
  • 2000-02-25 EP EP00907721A patent/EP1155185B1/fr not_active Expired - Lifetime
  • 2000-02-25 AU AU29214/00A patent/AU2921400A/en not_active Abandoned
  • 2000-02-25 DE DE60009869T patent/DE60009869T2/de not_active Expired - Lifetime
  • 2000-02-25 AT AT00907721T patent/ATE264425T1/de active
• 2001
  • 2001-08-24 NO NO20014132A patent/NO317608B1/no not_active IP Right Cessation

Patent Citations (4)

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