CA2016966A1 - Method and an apparatus for treating fiber suspension - Google Patents
Method and an apparatus for treating fiber suspensionInfo
- Publication number
- CA2016966A1 CA2016966A1 CA002016966A CA2016966A CA2016966A1 CA 2016966 A1 CA2016966 A1 CA 2016966A1 CA 002016966 A CA002016966 A CA 002016966A CA 2016966 A CA2016966 A CA 2016966A CA 2016966 A1 CA2016966 A1 CA 2016966A1
- Authority
- CA
- Canada
- Prior art keywords
- filter
- accordance
- counter
- suspension
- fraction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/18—Drum screens
- B07B1/20—Stationary drums with moving interior agitators
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Paper (AREA)
Abstract
Abstract The present invention relates to a method and an apparatus for treating fiber suspension. The method and apparatus are especially suitable for power screening of fiber suspension flowing to the head box of a paper machine.
In known filter apparatuses the accept pulp is thickened or diluted, the distribution of pulp fraction is changed and the filter apparatuses have created pulses in the accept pulp. In order to eliminate or minimize these problems a new type of a rotor (7) has been developed to be used with the filter cylinder, on the surface of which on the filter cylinder side protrusions (10) of different shape have been arranged, by which protrusions not only is the filter cylinder (6) kept clean, but also is affected on the axial flow of the fiber suspension.
(Fig. 3)
In known filter apparatuses the accept pulp is thickened or diluted, the distribution of pulp fraction is changed and the filter apparatuses have created pulses in the accept pulp. In order to eliminate or minimize these problems a new type of a rotor (7) has been developed to be used with the filter cylinder, on the surface of which on the filter cylinder side protrusions (10) of different shape have been arranged, by which protrusions not only is the filter cylinder (6) kept clean, but also is affected on the axial flow of the fiber suspension.
(Fig. 3)
Description
A METHOD AND A~ APPARATUS FOR TREATING FIBER SUSPENSION
The present invention relates to a method and an apparatus for treating fiber suspension. The method in accordance with the invention is especially suitable for screening pulps of the pulp and paper industry and also for thickening. The apparatus part of the invention relates to a rotor construction of a power screen or a thickener.
There are, in principle, two previously known types of rotor arrangements, which both are commonly used and the purpose of which is, as well known, to maintain the filter surface clean, in other words to prevent the generation of a fiber matting on the filter surface. An example of one of the types can be appreciated for example, from the U.S. patent 4193865 issued March 18, 1980, which discloses a rotor arrangement, in which a rotatable rotor is arranged inside a cylindrical, stationary filter cylinder, and which rotor comprises blades located close to the surface of the filter cylinder, which blades in the construction in accordance with said patent form an angle with the axis of the cylinder. The filter surface is subjected to pressure pulses when the blades move and the pressure pulses consequently open the openings on the surface. There are also arrangements, in which the blades are located on both sides of the filter cylinder. In such a case the suspension being treated is introduced either to the inside or the outside of the cylinder and the discharge of the accept respectively takes place on the outside or the inside of the cylinder.
An example of the second type is, for example, an arrangement in accordance with US patent 3437204 issued April 8, 1969, in which the rotor is a substantially cylindrical, closed piece, the surface of which has almost hemispherical protrusions.
The pulp in this type of apparatus i5 A
introduced to the treating space between the rotor cylinder and the filter cylinder outside the rotor cylinder, whereby the purpose of the rotor protrusions, so called bumps, is both to press the pulp against the filter cylinder and to draw the matted pulp with the trailing edge from the openings of the filter cylinder.
Because this type of construction has a highly thickening effect on the pulp, three dilution water conduits have been mounted in the arrangement in accordance with the above mentioned patent at different levels in the filter cylinder so as to satisfactorily carry out the screening of the fiber suspension. A corresponding "bump rotor" is disclosed also in US patent 3363759 issued January 16, 1968, in which the rotor is slightly conical for the reason explained later on in this description.
Also other embodiments are known of the above mentioned cylindrical rotor, in a connection of which different kinds of protrusions on the filter cylinder side are considered to be used within different specifications.
German patent application 3006482 published October 8, 1981 (J.M. Voith GmbH) discloses a knotter, which has on the surface of a cylindrical rotor drum plough-shaped protrusions made of plate material, the purpose of which is to create strongly mixing forces in the pulp between the rotor and the filter cylinder so that the fibers would penetrate the filter cylinder as effectively as possible and the knots, chips and the like were separated from the rest.
US patents 4188286 issued February 12, 1980 and 4202761 issued May 13, 1980 illustrate a filter apparatus, which has a rotatable cylindrical rotor inside the filter cylinder.
Protrusions have been arranged on the rotor surface on the filter cylinder side, and the protrusions are V-shaped of their axial cross-section in such a way that the one rotational edge has an evenly . . .
rising front surface, a gurface parallel to the rlm of the rotor and a back surface substantially perpendlcular agalnst the rotor surface. These pro~rusions are arranged on the surface of the rotor cylinder ~n a particular angle position relative to the axial directlon so that all tha protrusions of the rotor are at a slmilar position relatlve to the axis of the rotor.
Accordlng to the US patent specifications pulp can be introduced into this apparatus at either slde of the filter cyllnder. If pulp ls lntroduced to the outside of the fllter cyllnder and the accept ls discharged from the inside of the filter cylinder, in other words from the rotor side, the rotatlonal direction of the rotor is such that the accept is sub~ected to a downwardly inclined force component by the angle position of the protrusions and that said inclined/rising ~urface of the protrusions operates as a front ~urface. If, again, the pulp ls lntroduced between the rotor and the filter cylinder, ln other words the accept ls discharged from the outside of the fllter cylinder, the rotational direction is opposite relative to the prevlously descrlbed, the protruslons tend to slow down the downwardly flowlng pulp and the surface which ls perpendlcular relative to the surface of the rotor cylinder operates as the front surface.
Practical industrial experiments have, however, proved that the above described apparatuses do not operate satisfactorily in all application conditions. For example, the first mentioned blade rotor creates too strong pressure pulses at the accept side of the filter cylinder, and is not therefore suitable, for example, in head boxes of the paper machines, since they should not have any fluctuation of pressure. The apparatus also tends to dilute the accept, and therefore the blade rotor ls not applicable ln apparatuses, whlch require pulp of a constant consistency.
Slnce the blades, (4 to 8 blades) ln the blade rotor are spaced relatlvely far from each other, a fiber matting always accumulates on the surface of the filter cyllnder before the next blade scrapes lt off. Thus the use of the fllter ls not effectlve. Addltlonally, said rotor type is expenslve to manufacture due to accura~e shapes of the blades and a careful finlshlng.
A substantlally cyllndrlcal rotor lllustrated as another model, which has almost hemlspherlcal protruslons, operates ln some applicatlons almost ideally, but, for example, wlth the head box of a paper machlne lts operatlon can be provlded wlth addltlonal precondltlons. Because the pulp suspenslon flowlng to the head box should be homogeneous, both ln conslstency and ln flber slze, the power screen should not vary these values. However, thls klnd of a "bump rotor" tends to dllute accept and addltlonally lt causes fluctuatlon in the conslstency values. In the performed experlments lt was dlscovered that a rotor of a certain mentloned type diluted accept between -0.15 to-0.45 ~ when the accept consistency was 3 %. Consequently, the consistency varles absolutely countlng +/- 5 %, which is too much when alming at a homogeneous and quallfled flnal product. On the other hand, fractionation also takes place in the screen comprising a "bump rotor~, in other words the mutual relation between the fractlons of the fiber suspension supplied to the filter cylinder changes in the screen in such a way that the relation of the fractions of the accept is no longer the same as that of the orlginally supplied pulp. With a "bump rotor" the extent of change of said fractionation was in the experiments between 5 to 10 ~ according to the clearance of the filter cylinder and the rotor. The corresponding extent of change with a blade rotor was about 20 ~ and therefore even a "bump rotorN is a considerable improvement to the previous apparatuses.
These defect~ of a filter apparatus provlded with a ~bump rotor n described above have led to some improvement attempts, such as the above mentioned guidance of the dilution water to the filter surface and in another case the slightly conical shape of the rotor. Both described alternatives reflect the problem occurring in communica~lon with the cylindrical rotor i.e. the uneverness in the use of a filter cyllnder in its different zones. A fact is that the flow through the filter cylinder is at its greatest immediately after pulp has come into communicatlon with the cylinder and the rotor. Consequently the pulp thickens to some extent and when the pulp flows downwardly along the surface of the filter cylinder, the amount of the suspension flowing through the filter openlngs continuously diminishes.
Attempt~ have been made to prevent this by feedlng dilution water to different levels of the fllter surface, whlch results ln a sllghtly more effective operation of the fllter cylinder, but which also results in the disadvantage of a relatively high dilution of the accept. Another possibility is to vary the clearance be~ween a filter cylinder and a rotor, whereby a greater clearance in the upper part of the filter apparatus enables a hlgher speed of the downwardly flowing pulp, whereby the pulp fills the clearance better and more homogeneously.
A respective operating method is appreciated from the arrangement disclosed in the US-patent application 4188286, in which the protrusions are inclined relative to the axis of the filter cylinder. The main purpose of the inclinatlon is to prevent the fiber or fiber flocs from attaching to the front edge of the protrusion and from being conveyed with it. A secondary purpose is to bring the accept pulp in the treatment space between the rotor and the filter cylinder sub~ect to a downward force component, by which it ls possible to accelerate to some extent the operatlon of a filter apparatus, st least to accelerate the dlscharge of the accept from the fllter.
The most developed embodlment ln the market at the moment ls lllustrated by the method ln accordance wlth FI patent 77279 and by the arrangement developed to realize thls method. The method ln accordance wlth sald patent ls characterlzed ln that flber suspe~slon ls sub~ected to axlal forces, the lntenslty and the dlrectlon of whlch vary accordlng to the mutual axlal posltion between the polnt of appllcation and the counter surface of the fllter cyllnder, and which are utllized to change the axial speed profile of the fiber suspension yet maintaining the dlrectlon of the flow contlnuously towards the discharge end.
The apparatus ln accordance wlth sald lnventlon is characterlzed ln that at least one of the counter surfaces of the fllter cylinder, belng agalnst the other, has at least one bump or the llke, the dlrection of the front surface of whlch varleg accordlng to the axlal positlon of the bump and by whlch the pulp partlcle ln the space between the counter surfaces ls sub~ected to an axlal force component, the lntenslty of whlch varies ln functlon of the axlal posltlon of the counter surfaces of the pulp partlcles, and which changes the speed profile of the flber suspenslon flowing between the comter surfaces.
Although the arrangement and the method in accordance with the invention are superior over the prior art technique, it is stlll possible to further develop the method described in the patent specification and the technical arrangement realizing it. Minute experiments have shown that all rotors, whlch use any klnd of protrusions whether they are of bladellke, hemlspherical, rectangular or any other type, have beglnning from the peak of said protrusion towards the tralllng dlrectlon, pulp, whose conslstency and re~ect content is hlgher than approxlmltely ln the screening zone. Thls i8, of course, due to the fact that the pressure stroke caused on the pulp by the bump has pressed acceptable material through the fllter surface, whereby both llquid and acceptable fiber material flows through the screen surface. It has also been dlscovered in the experlments that sald pulp whlch has a hlgher consistency and which contains more re~ectable materlal tends to remain against the screen surface regardless of the fact that the effect of the bump on the rotor on said pulp portion stops. This, of cource, weakens the capacity of the screener, because fresh or less screened pulp must first penetrate said layer of a higher con8igtency to pass the filter. When thickeners are concerned the fiber mattlng accumulated on the filter surface causes a situation where in order for the flltrate to pass the opening of the fllter surface it must also be pressed through said fiber matting.
The present inventio~ relates to a method and apparatus for conveying the above mentloned thlcker and coarser pulp portion from the fllter surface towards the surface of the rotor so that the fresher pulp comes into dlrect communication with the filter surface, whereby the defects or disadvantages of the prior art apparatuses have been eliminated or minimized.
The method in accordance with the present invention is characterized in that the fraction concentrated ad~acent to the filter surface and/or containing coarser material is sub~ected to a force component directed away from the filter surface, by means of which sald fraction is conveyed away from the ad~acence of the filter surface.
An embodiment of the apparatus in accordance wlth the present invention ls characterized in that at least one gulde plate i3 arranged to communlcate with the counter member of the fllter surface, whlch gulde plate guldes the coarser and/or thlcker suspension concentrated ad~acent to the fllter surface, away from the ad~acence of the filter surface.
Another embodlment of the apparatus ln accordance wlth the present lnventlon ls characterlzed ln that the counter surface to the fllter surface has at least one member, whlch ls formed by a protruslon arranged on the counter surface and a gulde plate extendlng from the level o~ the counter surface hlgher than sald protruslon, whlch protruslon and guide plate leave an opening therebetween, through which the thicker and/or coarser fraction can flow under the guide plate.
The method and apparatug in accordance wlth the present invention are described more in detail below, by way of example, with reference to the accompanying drawlngs, in whlch:
Flg.l is a schematlc illustratlon of a screener in accordance with FI Patent 77279;
Fig.2 is a schematlc side view of a protrusion of a rotor described in the above mentioned FI patent of a screener in accordance with Fig.l;
Flgs.3 _ and b are schematlc illustrations of a protrusion of a rotor in accordance with a preferred embodiment of the present inventlon developed for the apparatus in accordance with Fig.l; Fig. 3_ is a section on the line D-D of Fig. 3b which is a section on line C-C of Fig.
3a and with the rotor surface omitted;
Figs.4 _ and _ are schematic illustrations of an auxlliary apparatus for intensifying the operation of the protrusion in accordance with the invention arranged into communlcatlon with an embodlment ln accordance wlth Flg.3; and Flgs.5 _ and b are schematlc sectional lllustrations of two protruslon arrangements ln accordance with a second embodiment of the lnvention to replace the substantlally spherlcal calotte shaped protrusions of a so called "bump~ rotor, wlth Flg. 5c being a plan of the protrusions of Flgs. 5_ and 5_ as such look the same ln plan and wlth the rotor surface belng omitted.
Accordlng to Flg.l a fllter apparatus 1, ln accordance with a preferred embodlment of the inventlon, comprises the following members: an outer caslng 2, conduit 3 for the lnflowlng pulp, condults 4 and 5 for the accept and the reJect respectlvely, a statlonary fllter cylinder 6 and thereln a substantially cyllndrlcal or possibly conlcal rotor 7 having a shaft 8 wlth drlve means 9. The filter cylinder 6 may, ln princlple, be of any prevlously known type, but the best results are achleved, if a contoured filter cylinder ls used. Generally, the apparatus ln accordance with the drawlng operates ln such a way that the flber suspension is introduced through conduit 3 and flows to the gap between the filter cylinder 6 and the rotor 7, to the so called n treatment" space. The accept, which has flowed through the openlngs of the filter cylinder - when a thlckener is in question the filtrate corresponds to the accept - is discharged through the conduit 4 as far as to the lower end of the gap between the filter cylinder 6 and the rotor 7 and the pulp, which flows away from the gap is discharged through the reiect conduit 5. Fig.l also teacheg that members 10 on the surface of the rotor 7, on the side faclng the f~lter cylinder 6 the shape of which members 10 may vary, for example, in the way described in FI patent 77279, according to in which zone the~ are located, in other words, ln whlch axlal part of the rotor they are located.
Flg.2 ls a schematlc lllugtration of a member lO, the front surface 11 of whlch may be either parallel to the dlrectlon of the axl-~ of the cyllnder, lncllned to some directlon relatlve to the axls or further dlvlded lnto portlons, the incllnatlon of whlch portlons relative to the axls may be chosen as deslred. Thls klnd of front surface 11, when movlng relatlve to the pulp towards arrow B subJects the pulp not only to a tangential force component, but also almost always to an axial force component which pumps pulp towards the center area of the cylinder and also always to a pressure stroke towards the fllter surface, lntenslfylng the pulp treatment, due to the effect of which the acceptable fiber materlal and liquld are pressed through the fllter and a zone of coarser, to some extent thlckened materlal ls generated on the surface of the filter. The front surface 11 of a member lO ln accordance wlth an embodlment of FI patent 77279 ls substantially perpendlcular agalnst the surface of rotor 7. The front surface 11 may, of course, also be lncllned elther to one or the other dlrectlon. The protruslon has a part 13 substantlally parallel to the surface of rotor 7 and an inclined surface 14 descendlng from part 13 to the surface of the rotor 7.
The above mentioned pressure stroke, which intensifies screening and also thickenlng, is generated exactly at the front surface of the protrusion or slightly before it, and on the other hand an underpressure zone has tended ~o be created on the incllned surface of the trailing side of the protrusion, which zone would draw said coarser and thickened material away from the ad~acence of the filter surface.
Flgs. 3_ and 3b illustrate a protrusion arrangement 20 of the rotor in accordance with an embodiment of the present P762E~/E8 lnventlon, ln whlch arrangement a pressure pulse towardq the filter surface ls generated by a protruslon 22, which, ln princlple, may be of any shape. Slgnlflcant of the protruslon arrangement 20 ig that a member 26 ha been arranged at the tralllng slde of the front surface 24 of the protruslon 22 whlch member extend~ closer to the lnner surface of the fllter 6 than the protruslon 22. Member 26 ls further characterlzed by a gap 28 formed between the member and the protruslon 22, through whlch the thlcker and coarser pulp generated between the protruslon and the fllter surface 18 allowed to pass to the space between member 26 and the rotor surface, from where it is further dlscharged to the ad~acence of the rotor surface, as arrows A ln Flgs. 3_ and 3b illustrate. Consequently, an underpressurlzed zone ls generated between the member and the fllter surface, whlch zone ls fllled by fresher, less treated pulp. The member 26 ls formed by a gulde plate 30 made of bent plate materlal in the embodiment of the flgure, which plate 30 corresponds to the inclined tralllng surface 14 of the member lO ln the arrangement illustrated in Flg.2 creatlng a corresponding underpressure stroke on the fllter surface, and by a plate 32 located on the flow inlet side of the protrusion 20 (most usually at the level of the upper surface of the protrusion when the rotor is vertically positioned). Plate 32 prevents the flow of the fiber materlal, whlch has flowed under part 26 from flowing to the upstream side of the protrusion, and on the other hand, also the suspension flowing along the surface of the rotor from flowing under the guide plate 30.
Fig.4 illustrates a protrusion 20 ~n accordance with Fig.3, which communicates with a backwardly lnclined plate 40 arranged to the downstream side of it, the purpose of which plate 40 ls to guide the unscreened or at least less screened pulp, which has flowed along the surface of the rotor, from under the part 26 to above the flowing pulp layer. In other wordg the ob~ectlve is to replace the thickened pulp lncludlng reJect and flowlng accordlng to arrow A by fregh pulp flowlng from the fllt~r surface ad~acent to the rotor surface according to arrow E.
Flgs. 5_, _ and _ lllustrate how the pulp replacement ln accordance wlth the lnvention may be reallzed when so called bump rotors ln accordance wlth the prior art are used. As known, the bump is formed elther by an exactly hemlspherlcal or at least a sherical calotte-shaped protrusion, which may either be a closed protrusion 50 (Fig.S_) attached to the ~urface of the rotor or ln some cases possibly a protruslon 52 (Flg.5b) pressed on the casing of the rotor from inside of the rotor. In that case a scraper 54 may of cour~e be either a completely separate bent protruslon made of metal or the llke material (Flg.5_) - or a protruslon pressed more deeply from lnslde of the surface of the rotor (Flg.Sb), whlch protruslon ls open substantlally from the top and from the downstream slde as lllustrated ln Figs.5b and 5c.
The operation corresponding to the prevlous embodlments may be created by a so called blade, for example, in such a way that both the outer and the lnner surfaces of the blade are provided with guide plates arranged wlthin certaln dlstances from each other, whlch gulde plates either "cut~
coarser flber material, thlckened ad~acent to the filter surface, carry lt into the blade and remove it on the tralling edge of the blade to the other side of the blade or gulde ln a corresponding way fresher, less treated suspension through the lnner space of the blade to the fllter surface. Naturally, said flow passages of the suspenslon lnslde the blade must be separated from each other wlth lntermedlate walls, which may be elther perpendicular against the blade surfaces or in a suitably chosen angle relatlve to them. The guide plates are further characterized ln that they are located lntermlttently relatlve to each other on the opposite surfaces of the blade.
An alternatlve to the above described arrangement i8 to arrange the guide plates above the blade surface wlth lntermedlate members ln such a way that the flow ~f the deslred pulp fractlon takeg place from between the blade and the guide plate. By varylng the locatlon of these gulde plates or the gulde plates mentloned ln the prevlous alternatlve to different parts of the blade, the pulp replacement process described already wlth the previous embodlments ls carrled out.
A rotor provided with the protrusion or blade construction in accordance wlth the invention is applicable to be utlllzed both with smooth and grooved filter cylinders, so the fllter cylinder may be either completely smooth or grooved ln different ways, as described ln FI-patent 77279.
Thus by utllizlng thege arrangements ln accordance wlth the lnventlon new rotors may be applled in older type of filter cyllnders and vlce versa. Thls results in a fllter cyllnder-rotor combinatlon operatlng better than the prevlous screening and thickening arrangements.
The rotor arrangement ln accordance with the invention was tested in the performed experiments in connection with dlf~erent filter cyllnders and different rotors were compared with each other. The filter cyllnders used in the experlments were both smooth cylinders and cylinders made of dlfferent plate contours. The test results were examined and lt was dlscovered that the apparatus in accordance with the lnventlon operates wlth all filter cyllnders more effectlvely than the other rotors. In other words the most preferred fllter embodlment accordlng to these tests was a fllter cyllnder, the grooves of whlch were formed substantlally by the bottom surface parallel to the cyllnder caslng, the lncllned slde ~urface on the upstream side (the lnflow dlrectlon of the flow) relatlve to the bottom surface and the slde gurface substantially perpendlcular agalnst the caslng surface of the cyllnder on the downstream slde relative to the bottom surface.
As ls clear from the above descrlptlon, the method and apparatus ln accordance wlth the lnventlon have enabled the ellmlnatlon or mlnlmlzatlon of the defects of the methods and apparatugeg of the prlor art and at same tlme lt has been posslble to galn conslderable increases ln the maxlmum capacity. However, it must be noted that above descrlption includes only a few most important embodiments of our lnvention, whlch are by no means glven to restrict the scope of invention from what ls deflned ln the accompanylng clalms, whlch alone deflne the scope of lnventlon.
The present invention relates to a method and an apparatus for treating fiber suspension. The method in accordance with the invention is especially suitable for screening pulps of the pulp and paper industry and also for thickening. The apparatus part of the invention relates to a rotor construction of a power screen or a thickener.
There are, in principle, two previously known types of rotor arrangements, which both are commonly used and the purpose of which is, as well known, to maintain the filter surface clean, in other words to prevent the generation of a fiber matting on the filter surface. An example of one of the types can be appreciated for example, from the U.S. patent 4193865 issued March 18, 1980, which discloses a rotor arrangement, in which a rotatable rotor is arranged inside a cylindrical, stationary filter cylinder, and which rotor comprises blades located close to the surface of the filter cylinder, which blades in the construction in accordance with said patent form an angle with the axis of the cylinder. The filter surface is subjected to pressure pulses when the blades move and the pressure pulses consequently open the openings on the surface. There are also arrangements, in which the blades are located on both sides of the filter cylinder. In such a case the suspension being treated is introduced either to the inside or the outside of the cylinder and the discharge of the accept respectively takes place on the outside or the inside of the cylinder.
An example of the second type is, for example, an arrangement in accordance with US patent 3437204 issued April 8, 1969, in which the rotor is a substantially cylindrical, closed piece, the surface of which has almost hemispherical protrusions.
The pulp in this type of apparatus i5 A
introduced to the treating space between the rotor cylinder and the filter cylinder outside the rotor cylinder, whereby the purpose of the rotor protrusions, so called bumps, is both to press the pulp against the filter cylinder and to draw the matted pulp with the trailing edge from the openings of the filter cylinder.
Because this type of construction has a highly thickening effect on the pulp, three dilution water conduits have been mounted in the arrangement in accordance with the above mentioned patent at different levels in the filter cylinder so as to satisfactorily carry out the screening of the fiber suspension. A corresponding "bump rotor" is disclosed also in US patent 3363759 issued January 16, 1968, in which the rotor is slightly conical for the reason explained later on in this description.
Also other embodiments are known of the above mentioned cylindrical rotor, in a connection of which different kinds of protrusions on the filter cylinder side are considered to be used within different specifications.
German patent application 3006482 published October 8, 1981 (J.M. Voith GmbH) discloses a knotter, which has on the surface of a cylindrical rotor drum plough-shaped protrusions made of plate material, the purpose of which is to create strongly mixing forces in the pulp between the rotor and the filter cylinder so that the fibers would penetrate the filter cylinder as effectively as possible and the knots, chips and the like were separated from the rest.
US patents 4188286 issued February 12, 1980 and 4202761 issued May 13, 1980 illustrate a filter apparatus, which has a rotatable cylindrical rotor inside the filter cylinder.
Protrusions have been arranged on the rotor surface on the filter cylinder side, and the protrusions are V-shaped of their axial cross-section in such a way that the one rotational edge has an evenly . . .
rising front surface, a gurface parallel to the rlm of the rotor and a back surface substantially perpendlcular agalnst the rotor surface. These pro~rusions are arranged on the surface of the rotor cylinder ~n a particular angle position relative to the axial directlon so that all tha protrusions of the rotor are at a slmilar position relatlve to the axis of the rotor.
Accordlng to the US patent specifications pulp can be introduced into this apparatus at either slde of the filter cyllnder. If pulp ls lntroduced to the outside of the fllter cyllnder and the accept ls discharged from the inside of the filter cylinder, in other words from the rotor side, the rotatlonal direction of the rotor is such that the accept is sub~ected to a downwardly inclined force component by the angle position of the protrusions and that said inclined/rising ~urface of the protrusions operates as a front ~urface. If, again, the pulp ls lntroduced between the rotor and the filter cylinder, ln other words the accept ls discharged from the outside of the fllter cylinder, the rotational direction is opposite relative to the prevlously descrlbed, the protruslons tend to slow down the downwardly flowlng pulp and the surface which ls perpendlcular relative to the surface of the rotor cylinder operates as the front surface.
Practical industrial experiments have, however, proved that the above described apparatuses do not operate satisfactorily in all application conditions. For example, the first mentioned blade rotor creates too strong pressure pulses at the accept side of the filter cylinder, and is not therefore suitable, for example, in head boxes of the paper machines, since they should not have any fluctuation of pressure. The apparatus also tends to dilute the accept, and therefore the blade rotor ls not applicable ln apparatuses, whlch require pulp of a constant consistency.
Slnce the blades, (4 to 8 blades) ln the blade rotor are spaced relatlvely far from each other, a fiber matting always accumulates on the surface of the filter cyllnder before the next blade scrapes lt off. Thus the use of the fllter ls not effectlve. Addltlonally, said rotor type is expenslve to manufacture due to accura~e shapes of the blades and a careful finlshlng.
A substantlally cyllndrlcal rotor lllustrated as another model, which has almost hemlspherlcal protruslons, operates ln some applicatlons almost ideally, but, for example, wlth the head box of a paper machlne lts operatlon can be provlded wlth addltlonal precondltlons. Because the pulp suspenslon flowlng to the head box should be homogeneous, both ln conslstency and ln flber slze, the power screen should not vary these values. However, thls klnd of a "bump rotor" tends to dllute accept and addltlonally lt causes fluctuatlon in the conslstency values. In the performed experlments lt was dlscovered that a rotor of a certain mentloned type diluted accept between -0.15 to-0.45 ~ when the accept consistency was 3 %. Consequently, the consistency varles absolutely countlng +/- 5 %, which is too much when alming at a homogeneous and quallfled flnal product. On the other hand, fractionation also takes place in the screen comprising a "bump rotor~, in other words the mutual relation between the fractlons of the fiber suspension supplied to the filter cylinder changes in the screen in such a way that the relation of the fractions of the accept is no longer the same as that of the orlginally supplied pulp. With a "bump rotor" the extent of change of said fractionation was in the experiments between 5 to 10 ~ according to the clearance of the filter cylinder and the rotor. The corresponding extent of change with a blade rotor was about 20 ~ and therefore even a "bump rotorN is a considerable improvement to the previous apparatuses.
These defect~ of a filter apparatus provlded with a ~bump rotor n described above have led to some improvement attempts, such as the above mentioned guidance of the dilution water to the filter surface and in another case the slightly conical shape of the rotor. Both described alternatives reflect the problem occurring in communica~lon with the cylindrical rotor i.e. the uneverness in the use of a filter cyllnder in its different zones. A fact is that the flow through the filter cylinder is at its greatest immediately after pulp has come into communicatlon with the cylinder and the rotor. Consequently the pulp thickens to some extent and when the pulp flows downwardly along the surface of the filter cylinder, the amount of the suspension flowing through the filter openlngs continuously diminishes.
Attempt~ have been made to prevent this by feedlng dilution water to different levels of the fllter surface, whlch results ln a sllghtly more effective operation of the fllter cylinder, but which also results in the disadvantage of a relatively high dilution of the accept. Another possibility is to vary the clearance be~ween a filter cylinder and a rotor, whereby a greater clearance in the upper part of the filter apparatus enables a hlgher speed of the downwardly flowing pulp, whereby the pulp fills the clearance better and more homogeneously.
A respective operating method is appreciated from the arrangement disclosed in the US-patent application 4188286, in which the protrusions are inclined relative to the axis of the filter cylinder. The main purpose of the inclinatlon is to prevent the fiber or fiber flocs from attaching to the front edge of the protrusion and from being conveyed with it. A secondary purpose is to bring the accept pulp in the treatment space between the rotor and the filter cylinder sub~ect to a downward force component, by which it ls possible to accelerate to some extent the operatlon of a filter apparatus, st least to accelerate the dlscharge of the accept from the fllter.
The most developed embodlment ln the market at the moment ls lllustrated by the method ln accordance wlth FI patent 77279 and by the arrangement developed to realize thls method. The method ln accordance wlth sald patent ls characterlzed ln that flber suspe~slon ls sub~ected to axlal forces, the lntenslty and the dlrectlon of whlch vary accordlng to the mutual axlal posltion between the polnt of appllcation and the counter surface of the fllter cyllnder, and which are utllized to change the axial speed profile of the fiber suspension yet maintaining the dlrectlon of the flow contlnuously towards the discharge end.
The apparatus ln accordance wlth sald lnventlon is characterlzed ln that at least one of the counter surfaces of the fllter cylinder, belng agalnst the other, has at least one bump or the llke, the dlrection of the front surface of whlch varleg accordlng to the axlal positlon of the bump and by whlch the pulp partlcle ln the space between the counter surfaces ls sub~ected to an axlal force component, the lntenslty of whlch varies ln functlon of the axlal posltlon of the counter surfaces of the pulp partlcles, and which changes the speed profile of the flber suspenslon flowing between the comter surfaces.
Although the arrangement and the method in accordance with the invention are superior over the prior art technique, it is stlll possible to further develop the method described in the patent specification and the technical arrangement realizing it. Minute experiments have shown that all rotors, whlch use any klnd of protrusions whether they are of bladellke, hemlspherical, rectangular or any other type, have beglnning from the peak of said protrusion towards the tralllng dlrectlon, pulp, whose conslstency and re~ect content is hlgher than approxlmltely ln the screening zone. Thls i8, of course, due to the fact that the pressure stroke caused on the pulp by the bump has pressed acceptable material through the fllter surface, whereby both llquid and acceptable fiber material flows through the screen surface. It has also been dlscovered in the experlments that sald pulp whlch has a hlgher consistency and which contains more re~ectable materlal tends to remain against the screen surface regardless of the fact that the effect of the bump on the rotor on said pulp portion stops. This, of cource, weakens the capacity of the screener, because fresh or less screened pulp must first penetrate said layer of a higher con8igtency to pass the filter. When thickeners are concerned the fiber mattlng accumulated on the filter surface causes a situation where in order for the flltrate to pass the opening of the fllter surface it must also be pressed through said fiber matting.
The present inventio~ relates to a method and apparatus for conveying the above mentloned thlcker and coarser pulp portion from the fllter surface towards the surface of the rotor so that the fresher pulp comes into dlrect communication with the filter surface, whereby the defects or disadvantages of the prior art apparatuses have been eliminated or minimized.
The method in accordance with the present invention is characterized in that the fraction concentrated ad~acent to the filter surface and/or containing coarser material is sub~ected to a force component directed away from the filter surface, by means of which sald fraction is conveyed away from the ad~acence of the filter surface.
An embodiment of the apparatus in accordance wlth the present invention ls characterized in that at least one gulde plate i3 arranged to communlcate with the counter member of the fllter surface, whlch gulde plate guldes the coarser and/or thlcker suspension concentrated ad~acent to the fllter surface, away from the ad~acence of the filter surface.
Another embodlment of the apparatus ln accordance wlth the present lnventlon ls characterlzed ln that the counter surface to the fllter surface has at least one member, whlch ls formed by a protruslon arranged on the counter surface and a gulde plate extendlng from the level o~ the counter surface hlgher than sald protruslon, whlch protruslon and guide plate leave an opening therebetween, through which the thicker and/or coarser fraction can flow under the guide plate.
The method and apparatug in accordance wlth the present invention are described more in detail below, by way of example, with reference to the accompanying drawlngs, in whlch:
Flg.l is a schematlc illustratlon of a screener in accordance with FI Patent 77279;
Fig.2 is a schematlc side view of a protrusion of a rotor described in the above mentioned FI patent of a screener in accordance with Fig.l;
Flgs.3 _ and b are schematlc illustrations of a protrusion of a rotor in accordance with a preferred embodiment of the present inventlon developed for the apparatus in accordance with Fig.l; Fig. 3_ is a section on the line D-D of Fig. 3b which is a section on line C-C of Fig.
3a and with the rotor surface omitted;
Figs.4 _ and _ are schematic illustrations of an auxlliary apparatus for intensifying the operation of the protrusion in accordance with the invention arranged into communlcatlon with an embodlment ln accordance wlth Flg.3; and Flgs.5 _ and b are schematlc sectional lllustrations of two protruslon arrangements ln accordance with a second embodiment of the lnvention to replace the substantlally spherlcal calotte shaped protrusions of a so called "bump~ rotor, wlth Flg. 5c being a plan of the protrusions of Flgs. 5_ and 5_ as such look the same ln plan and wlth the rotor surface belng omitted.
Accordlng to Flg.l a fllter apparatus 1, ln accordance with a preferred embodlment of the inventlon, comprises the following members: an outer caslng 2, conduit 3 for the lnflowlng pulp, condults 4 and 5 for the accept and the reJect respectlvely, a statlonary fllter cylinder 6 and thereln a substantially cyllndrlcal or possibly conlcal rotor 7 having a shaft 8 wlth drlve means 9. The filter cylinder 6 may, ln princlple, be of any prevlously known type, but the best results are achleved, if a contoured filter cylinder ls used. Generally, the apparatus ln accordance with the drawlng operates ln such a way that the flber suspension is introduced through conduit 3 and flows to the gap between the filter cylinder 6 and the rotor 7, to the so called n treatment" space. The accept, which has flowed through the openlngs of the filter cylinder - when a thlckener is in question the filtrate corresponds to the accept - is discharged through the conduit 4 as far as to the lower end of the gap between the filter cylinder 6 and the rotor 7 and the pulp, which flows away from the gap is discharged through the reiect conduit 5. Fig.l also teacheg that members 10 on the surface of the rotor 7, on the side faclng the f~lter cylinder 6 the shape of which members 10 may vary, for example, in the way described in FI patent 77279, according to in which zone the~ are located, in other words, ln whlch axlal part of the rotor they are located.
Flg.2 ls a schematlc lllugtration of a member lO, the front surface 11 of whlch may be either parallel to the dlrectlon of the axl-~ of the cyllnder, lncllned to some directlon relatlve to the axls or further dlvlded lnto portlons, the incllnatlon of whlch portlons relative to the axls may be chosen as deslred. Thls klnd of front surface 11, when movlng relatlve to the pulp towards arrow B subJects the pulp not only to a tangential force component, but also almost always to an axial force component which pumps pulp towards the center area of the cylinder and also always to a pressure stroke towards the fllter surface, lntenslfylng the pulp treatment, due to the effect of which the acceptable fiber materlal and liquld are pressed through the fllter and a zone of coarser, to some extent thlckened materlal ls generated on the surface of the filter. The front surface 11 of a member lO ln accordance wlth an embodlment of FI patent 77279 ls substantially perpendlcular agalnst the surface of rotor 7. The front surface 11 may, of course, also be lncllned elther to one or the other dlrectlon. The protruslon has a part 13 substantlally parallel to the surface of rotor 7 and an inclined surface 14 descendlng from part 13 to the surface of the rotor 7.
The above mentioned pressure stroke, which intensifies screening and also thickenlng, is generated exactly at the front surface of the protrusion or slightly before it, and on the other hand an underpressure zone has tended ~o be created on the incllned surface of the trailing side of the protrusion, which zone would draw said coarser and thickened material away from the ad~acence of the filter surface.
Flgs. 3_ and 3b illustrate a protrusion arrangement 20 of the rotor in accordance with an embodiment of the present P762E~/E8 lnventlon, ln whlch arrangement a pressure pulse towardq the filter surface ls generated by a protruslon 22, which, ln princlple, may be of any shape. Slgnlflcant of the protruslon arrangement 20 ig that a member 26 ha been arranged at the tralllng slde of the front surface 24 of the protruslon 22 whlch member extend~ closer to the lnner surface of the fllter 6 than the protruslon 22. Member 26 ls further characterlzed by a gap 28 formed between the member and the protruslon 22, through whlch the thlcker and coarser pulp generated between the protruslon and the fllter surface 18 allowed to pass to the space between member 26 and the rotor surface, from where it is further dlscharged to the ad~acence of the rotor surface, as arrows A ln Flgs. 3_ and 3b illustrate. Consequently, an underpressurlzed zone ls generated between the member and the fllter surface, whlch zone ls fllled by fresher, less treated pulp. The member 26 ls formed by a gulde plate 30 made of bent plate materlal in the embodiment of the flgure, which plate 30 corresponds to the inclined tralllng surface 14 of the member lO ln the arrangement illustrated in Flg.2 creatlng a corresponding underpressure stroke on the fllter surface, and by a plate 32 located on the flow inlet side of the protrusion 20 (most usually at the level of the upper surface of the protrusion when the rotor is vertically positioned). Plate 32 prevents the flow of the fiber materlal, whlch has flowed under part 26 from flowing to the upstream side of the protrusion, and on the other hand, also the suspension flowing along the surface of the rotor from flowing under the guide plate 30.
Fig.4 illustrates a protrusion 20 ~n accordance with Fig.3, which communicates with a backwardly lnclined plate 40 arranged to the downstream side of it, the purpose of which plate 40 ls to guide the unscreened or at least less screened pulp, which has flowed along the surface of the rotor, from under the part 26 to above the flowing pulp layer. In other wordg the ob~ectlve is to replace the thickened pulp lncludlng reJect and flowlng accordlng to arrow A by fregh pulp flowlng from the fllt~r surface ad~acent to the rotor surface according to arrow E.
Flgs. 5_, _ and _ lllustrate how the pulp replacement ln accordance wlth the lnvention may be reallzed when so called bump rotors ln accordance wlth the prior art are used. As known, the bump is formed elther by an exactly hemlspherlcal or at least a sherical calotte-shaped protrusion, which may either be a closed protrusion 50 (Fig.S_) attached to the ~urface of the rotor or ln some cases possibly a protruslon 52 (Flg.5b) pressed on the casing of the rotor from inside of the rotor. In that case a scraper 54 may of cour~e be either a completely separate bent protruslon made of metal or the llke material (Flg.5_) - or a protruslon pressed more deeply from lnslde of the surface of the rotor (Flg.Sb), whlch protruslon ls open substantlally from the top and from the downstream slde as lllustrated ln Figs.5b and 5c.
The operation corresponding to the prevlous embodlments may be created by a so called blade, for example, in such a way that both the outer and the lnner surfaces of the blade are provided with guide plates arranged wlthin certaln dlstances from each other, whlch gulde plates either "cut~
coarser flber material, thlckened ad~acent to the filter surface, carry lt into the blade and remove it on the tralling edge of the blade to the other side of the blade or gulde ln a corresponding way fresher, less treated suspension through the lnner space of the blade to the fllter surface. Naturally, said flow passages of the suspenslon lnslde the blade must be separated from each other wlth lntermedlate walls, which may be elther perpendicular against the blade surfaces or in a suitably chosen angle relatlve to them. The guide plates are further characterized ln that they are located lntermlttently relatlve to each other on the opposite surfaces of the blade.
An alternatlve to the above described arrangement i8 to arrange the guide plates above the blade surface wlth lntermedlate members ln such a way that the flow ~f the deslred pulp fractlon takeg place from between the blade and the guide plate. By varylng the locatlon of these gulde plates or the gulde plates mentloned ln the prevlous alternatlve to different parts of the blade, the pulp replacement process described already wlth the previous embodlments ls carrled out.
A rotor provided with the protrusion or blade construction in accordance wlth the invention is applicable to be utlllzed both with smooth and grooved filter cylinders, so the fllter cylinder may be either completely smooth or grooved ln different ways, as described ln FI-patent 77279.
Thus by utllizlng thege arrangements ln accordance wlth the lnventlon new rotors may be applled in older type of filter cyllnders and vlce versa. Thls results in a fllter cyllnder-rotor combinatlon operatlng better than the prevlous screening and thickening arrangements.
The rotor arrangement ln accordance with the invention was tested in the performed experiments in connection with dlf~erent filter cyllnders and different rotors were compared with each other. The filter cyllnders used in the experlments were both smooth cylinders and cylinders made of dlfferent plate contours. The test results were examined and lt was dlscovered that the apparatus in accordance with the lnventlon operates wlth all filter cyllnders more effectlvely than the other rotors. In other words the most preferred fllter embodlment accordlng to these tests was a fllter cyllnder, the grooves of whlch were formed substantlally by the bottom surface parallel to the cyllnder caslng, the lncllned slde ~urface on the upstream side (the lnflow dlrectlon of the flow) relatlve to the bottom surface and the slde gurface substantially perpendlcular agalnst the caslng surface of the cyllnder on the downstream slde relative to the bottom surface.
As ls clear from the above descrlptlon, the method and apparatus ln accordance wlth the lnventlon have enabled the ellmlnatlon or mlnlmlzatlon of the defects of the methods and apparatugeg of the prlor art and at same tlme lt has been posslble to galn conslderable increases ln the maxlmum capacity. However, it must be noted that above descrlption includes only a few most important embodiments of our lnvention, whlch are by no means glven to restrict the scope of invention from what ls deflned ln the accompanylng clalms, whlch alone deflne the scope of lnventlon.
Claims (21)
1. Method of treating fiber suspension, in which method suspension is introduced to a space between a filter surface and its counter member, a so called treatment space, wherefrom the finer fraction is discharged through the openings of the filter surface and the coarser fraction remains in said space flowing to the discharge end of the filter surface and being discharged there from the apparatus, characterized in that the fraction concentrated adjacent to the filter surface and/or containing coarser material is subjected to a force component directed away from the filter surface, by means of which said fraction is conveyed away from the adjacence of the filter surface.
2. Method in accordance with claim 1, characterized in that less treated suspension is introduced to the filter surface to replace said fraction conveyed away.
3. Method in accordance with claim 2, characterized in that the fraction concentrated adjacent to the filter surface and/or containing coarser material is subjected to a force component directed away from the filter surface, by means of which said fraction is forced away from the adjacence of the filter surface.
4. Method in accordance with claim 1, characterized in that the fraction concentrated adjacent to the filter surface, and that less treated suspension is conveyed to the filter surface to replace said fraction by subjecting said suspension to a radial force component directed towards the filter surface.
5. Method in accordance with claim 1, characterized in that the fraction concentrated adjacent to the filter surface and/or containing coarser material is subjected to a force component directed away from the filter surface, by means of which said fraction is forced away from the adjacence of the filter surface and that less treated suspension is forced to the filter surface to replace said fraction by subjecting said suspension to a radial force component directed towards the filter surface.
6. Apparatus for treating fiber suspension, which apparatus (1) comprises an outer casing (2) provided with conduits (3,4 and 5) for the pulp being introduced, the finer fraction and the coarser fraction, and two devices operating with each other, of which one is a filter cylinder (6) and the other a counter member (7), whereby at least one of said devices (6,7) is rotatable, characterized in that at least one guide plate is arranged in connection with the counter member, which guide plate is such as to guide the coarser and/or thicker suspension concentrated adjacent to the filter surface away from the adjacence of the filter surface.
7. Apparatus for treating fiber suspension, which apparatus (1) comprises an outer casing (2) provided with conduits (3,4 and 5) for the pulp being introduced, the finer fraction and the coarser fraction, and two counter surfaces operating with each other, of which one is a filter cylinder (6) and the other a counter surface (7), which substantially corresponds of its form to the filter cylinder (6), whereby at least one of said counter surfaces (6,7) is rotatable, characterized in that the counter surface (7) has at least one member (10), which is formed by a protrusion (22,50,52) arranged on the counter surface (7) and a guide plate (30,54) extending from the level of the counter surface (7) higher than the protrusion, which protrusion and guide plate have an opening between them, through which the thicker and/or coarser fraction is allowed to flow under the guide plate (30,54) and sideways from under the guide plate (30,54).
8. Apparatus in accordance with claim 7, characterized in that the counter surface (7) is a rotatable rotor, the casing surface of which is provided on the side of the filter surface with at least one member (10), which is formed by a protrusion (22,50,52) arranged on the counter surface (7), and a guide plate (30,54) extending from the level of the counter surface (7) higher than the protrusion.
9. Apparatus in accordance with claim 7, characterized in that the guide plate (30,54) is attached to the counter surface (7) from the trailing side of the protrusion (22,50,52) in such a way that the guide plate (30,54) forms an acute angle with the counter surface (7), opening towards the protrusion (22,50,52).
10. Apparatus in accordance with claim 7, characterized in that the guide plate (30) is supported on the counter surface (7) on the plate (32) from the side of the protrusion (22), which receives the axial flow component of the suspension, which at the same time prevents the suspension flowing along the counter surface (7) from flowing under the guide plate (30).
11. Apparatus in accordance with claim 7, characterized in that the guide plate (54) is curved, advantageously part of a spherical surface, of its shape.
12. Apparatus in accordance with claim 7, characterized in that a blade member (40) is arranged on the trailing side of the protrusion (22,50,52) relative to the axial flow component of the suspension, by which blade member less treated suspension flowing in front of the protrusion (22,50,52) is guided towards the filter surface (6).
13. Apparatus in accordance with claim 6, characterized in that the counter member is a blade of a blade rotor, the inner space of which is formed by ducts substantially perpendicular against the axis of the apparatus or slightly deviating therefrom and the outer surface of which is provided with guide plates to guide the, thickened/coarser suspension away from the adjacence of the filter surface and/or to guide fresher suspension to the adjacence of the filter surface.
14. Apparatus in accordance with claim 6, characterized in that the counter member is a blade of a blade rotor, the surface of which on the side of the filter member is provided with a member of guide plates within certain distances and attached with intermediate members, and by means of which guide plates the pulp in the treatment space is guided away from the adjacence of the filter member.
15. Apparatus in accordance with claim 14, characterized in that the farther surface relative to the filter member of the blade is provided with a number of guide plates attached with intermediary members, which plates are located in the longitudinal direction of the blade between the guide plates on the opposite surface of the blade, whereby they guide fresher pulp to the treatment space.
16. Use of an apparatus in accordance with one of claims 6 or 7 for treating fiber suspensions of pulp and paper industry, characterized in that a filter cylinder is utilized in it having a grooved surface on the rotor side.
17. Use in accordance with claim 16, characterized in that a filter cylinder is utilized in it, the grooves of which are formed at least by a side surface, substantially perpendicular against the rim, and an inclined side surface.
18. Use in accordance with claim 16, characterized in that a filter cylinder is utilized in it, the grooves of which are formed by at least two inclined or curved side surfaces.
19. Use in accordance with claim 16, characterized in that a filter cylinder is utilized in it, the grooves of which are formed by a bottom surface, substantially parallel to the casing surface of the filter cylinder, an inclined side surface on the upstream side relative to the bottom surface and a side surface, substantially perpendicular against the casing surface on the downstream side relative to the bottom surface.
20. A counter member (7) on its own for use in an apparatus for treating fiber suspension, characterized in that at least one guide plate is provided on or formed from the counter member and is shaped and/or dimensioned so as in use to guide the coarser and/or thicker suspension concentrating adjacent the filter surface away from the adjacence of the filter surface.
21. A counter member in accordance with claim 20, having any of the features thereof claimed in anyone of claims 8 - 19.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI892356 | 1989-05-17 | ||
| FI892356A FI84191C (en) | 1989-05-17 | 1989-05-17 | Method and apparatus for treating fiber suspension |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2016966A1 true CA2016966A1 (en) | 1990-11-17 |
Family
ID=8528440
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002016966A Abandoned CA2016966A1 (en) | 1989-05-17 | 1990-05-16 | Method and an apparatus for treating fiber suspension |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0398685A1 (en) |
| JP (1) | JPH0364590A (en) |
| KR (1) | KR900017668A (en) |
| BR (1) | BR9002307A (en) |
| CA (1) | CA2016966A1 (en) |
| FI (1) | FI84191C (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4000248A1 (en) * | 1990-01-06 | 1991-07-11 | Emil Holz | ROTOR FOR PRESSURE SORTER FOR SORTING FIBER SUSPENSIONS |
| FR2666598B1 (en) * | 1990-09-10 | 1994-05-27 | Escher Wyss Gmbh | PROCESS FOR SEPARATING, ESPECIALLY SORTING OR SPLITTING A SUSPENSION OF PAPER PULP. |
| GB2284394B (en) * | 1992-09-02 | 1995-11-15 | Total Mobility Vehicles Ltd | Independent wheel suspension |
| JP2735089B2 (en) * | 1993-03-22 | 1998-04-02 | 株式会社サトミ製作所 | How to remove light and fine foreign matter |
| FR2790270B1 (en) * | 1999-02-26 | 2001-11-16 | Lamort E & M | PROCESSES AND MEANS FOR FILTERING PULP |
| SE526033C3 (en) * | 2003-11-06 | 2009-12-08 | Metso Paper Inc | Screening device and strainer for screening of pulp suspensions |
| CN117066107B (en) * | 2023-10-16 | 2023-12-12 | 甘肃省地质矿产勘查开发局第三地质矿产勘查院 | Be applied to piece removal equipment that charcoal thick liquid method carried gold |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3953325A (en) * | 1972-09-27 | 1976-04-27 | Nelson Douglas G | Pulp screen with rotating cleaning foil |
| JPS5841889A (en) * | 1981-09-05 | 1983-03-11 | Otsuka Chem Co Ltd | Production of condensed polyalkoxyphosphazene |
| FR2516563A1 (en) * | 1981-11-18 | 1983-05-20 | Lamort E & M | IMPROVEMENTS ON PAPER PULP CLEANERS AND THEIR SCREWS |
| JPS58133009A (en) * | 1982-02-02 | 1983-08-08 | Nippon Gakki Seizo Kk | Power amplifier |
| DE3322578C2 (en) * | 1983-06-14 | 1986-01-16 | Sulzer-Escher Wyss GmbH, 7980 Ravensburg | Sorting device |
| FI77279C (en) * | 1987-04-30 | 1989-02-10 | Ahlstroem Oy | FOERFARANDE OCH ANORDNING FOER BEHANDLING AV FIBERSUSPENSION. |
| EP0298499B1 (en) * | 1987-07-08 | 1994-03-16 | A. Ahlstrom Corporation | Method and apparatus for thickening fiber suspension |
-
1989
- 1989-05-17 FI FI892356A patent/FI84191C/en not_active IP Right Cessation
-
1990
- 1990-05-16 EP EP90305288A patent/EP0398685A1/en not_active Withdrawn
- 1990-05-16 CA CA002016966A patent/CA2016966A1/en not_active Abandoned
- 1990-05-17 BR BR909002307A patent/BR9002307A/en unknown
- 1990-05-17 JP JP2128089A patent/JPH0364590A/en active Pending
- 1990-05-17 KR KR1019900007217A patent/KR900017668A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| BR9002307A (en) | 1991-08-06 |
| JPH0364590A (en) | 1991-03-19 |
| FI84191C (en) | 1992-11-25 |
| KR900017668A (en) | 1990-12-19 |
| EP0398685A1 (en) | 1990-11-22 |
| FI892356A0 (en) | 1989-05-17 |
| FI84191B (en) | 1991-07-15 |
| FI892356A (en) | 1990-11-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |