Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F1/00—Wet end of machines for making continuous webs of paper
  • D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials

Definitions

• the present invention relates to a method and apparatus for recovering fibre and fibre-based solids from filtrates containing both solids and lipophilic extractive agents, i.e. extractives of mechanical or chemi-mechanical pulp industry
• Lipophilic extractives i.e. mainly resin from wood, cause various problems particularly in the production of pulp and paper from mechanical or chemi- mechanical pulp. The most common problems are fouling of wires and showers, and deposits at the paper machine. Lipophilic extractives and their deposits also decrease the strength and brightness properties of the paper and cause holes in the paper.
• TMP ThermoMechanical Pulping
• CTMP ChemiThermoMechanical Pulping
• GW GroundWood
• PGW Pressure GroundWood
• APMP Alkaline Peroxide Mechanical Pulping
• CMP ChemiMechanical Pulping
• Modifying the water circulations and the use of more efficient washing equipment means in practice increasing the loss of solids multifold compared with the present situation. Modifying the water circulations alone would increase the solids loss to be even 4 - 5 fold compared with the present. More efficient presses in the wash of lipophilic extractives would increase the solids loss even from this up to 3 - 6 fold. Further, more efficient presses separate from the pulp to the water fine solids, which would have a clearly improving influence on the optic properties in the paper to be producing. Thus, if the filtrate from this press was removed from the process, the optic properties of the pulp would deteriorate. Changing the water circulations and employing more efficient presses presuppose development of more efficient fibre recovering equipment and introducing them into use.
• a PWG (Pressure Ground Wood) process Fig. 1
• the wood is introduced into the process as logs which are then ground at 2 at a high pressure to a fibre suspension.
• the thickening device 4 is called a hot loop thickener.
• the consistency of the fibre suspension is raised by removing from it filtrate, which is introduced into a hot water tank 6. Part of the filtrate in question is pumped from the hot water tank 6 to serve as shower water in refining while the rest flows into a channel 8 and further to the water cleaning system of the mill.
• the fibre suspension thickened in the hop loop thickener 4 is then introduced into sorting 10, however, before that the suspension is diluted, 12, with liquid obtained at least partly from the process itself.
• sorting 10 the fibre suspension continues to a disc filter 14, which again removes liquid/filtrate from the suspension.
• Filtrates of two types are obtained from the disc filter 14 by conventional methods, i.e. a clear filtrate and a cloudy filtrate, each into its own filtrate tank 16 and 18. Sometimes also a so-called super clear filtrate is separated which practically does not contain fines at all.
• the thickened fibre suspension flows to a bleach press 20 with which the consistency of the suspension is raised to the level required by the bleaching process. Filtrate from the bleach press 20 is collected to a bleach press filtrate tank 22 and from there in most cases all of it is used in the dilution 24 preceding the disc filter 14.
• the thickened fibre suspension from the bleach press 20 flows to a bleaching 26 (peroxide bleaching in the figure), which is followed by a washing press 28, which aims at removing reaction products of the bleaching from the fibre suspension. After the washing press 28 the suspension travels to the paper mill while the filtrate from the washing press 28 flows to a washing press filtrate tank 30.
• the filtrate collected there is used with filtrate from the bleach press 20 in the dilution 24 preceding the disc filter 14 and with fresh water in a dilution 32 preceding the washing press 28. It should be noted from the above description that the several dilution and the following pressing and thickening stages mentioned above mean in practice washing the fibre suspension whereby extractives or other substances detached from the fibres during the process and intended to be removed, are washed from the suspension.
• Table I presents extractive and solids contents of various filtrates in a prior art process (Fig. 1) and Table II illustrates solids contents and extractives retentions of various filtrates from prior art presses
• fibre recovery is usually not employed, or if it is, the fibre recovery is based on screening and filtering methods or flotation. Problems with these methods are for example: the low consistency of the recovered solids, the retention of lipophilic extractives into the solids to be recovered and/or the poor solids recovery degree. The problems in the separation are mostly due to the high fines content in the filtrate, the size of the lipophilic extractives is approx. 0.1 - 2 ⁇ m and the size of the fibre material >5 ⁇ m which means that the filtering must employ a small hole size.
• the result achievable with the present fibre recovery methods is a compromise between the volume of the recovered fibres and the extractives load recycled to the process. Table III presents results obtained with various fibre recovery apparatus.
• the most common fibre recovering apparatus are disc and drum thickeners in which the fibre and the fines are filtered through a solids cake as completely as possible. This method gives a fairly high solids recovery degree but at the same time the solids cake filters efficiently also colloidal substances off from the water. If the thickness of the solids cake is decreased the retention of colloids decreases but also the solids recovery efficiency decreases.
• the flotation method gives a high degree of solids recovery.
• air bubbles remove also colloidal material with the solids.
• a drawback of a flotator is the low consistency of the recovered material and the large share of the colloidal detrimental material returning o the process.
• Fig. 1 illustrates a prior art process of manufacturing mechanical pulp
• Figs. 2a and 2b illustrate schematically the operation principle of two different centrifuges
• Fig. 3 illustrates a so-called decanter centrifuge
• Fig. 4 illustrates a so-called screen bowl centrifuge
• Fig. 5 illustrates the results of a mill-scale test run of the method of the invention
• Fig. 6 illustrates a flow sheet used in the simulation of the method of the invention
• Fig. 7 illustrates the solids losses of the process obtained from the simulation according to Fig. 6 with different solids recovering methods, as a function of the volume of the filtrate taken to the solids recovery
• Fig. 8 illustrates the solids losses of the process obtained from the simulation according to Fig. 6 with various process filtrates, as a function of the volume of the filtrate discharged from the process
• Fig. 9 illustrates the separation efficiencies of lipophilic extractives obtained from the simulation according to Fig. 6 with various process filtrates, as a function of the volume of the filtrate discharged from the process;
• Fig. 10 illustrates the separation efficiencies of lipophilic extractives obtained from the simulation according to Fig. 6 with various solids recovery methods, as a function of the volume of the filtrate taken to the solids recovery;
• Fig. 11 illustrates the consistencies of the discharged pulp obtained from the simulation according to Fig. 6 with various solids recovery methods, as a function of the volume of the filtrate taken to the solids recovery;
• Fig. 12 illustrates a preferred process application of the method and the apparatus of the invention;
• Fig. 13 illustrates another preferred process application of the method and the apparatus of the invention
• Fig. 14 illustrates a third preferred process application of the method and the apparatus of the invention.
• Fig. 15 illustrates a fourth preferred process application of the method and the apparatus of the invention.
• Fig. 16 illustrates a fifth preferred process application of the method and the apparatus of the invention
• Fig. 17 illustrates a sixth preferred process application of the method and the apparatus of the invention
• Fig. 18 illustrates a seventh preferred process application of the method and the apparatus of the invention.
• Fig. 19 illustrates an eighth preferred process application of the method and the apparatus of the invention.
• Centrifuging means a sorting or a separation process based on the centrifugal force.
• the centrifugal force created in the centrifuging has the same kind of an effect on material as the gravitational force in settling.
• the centrifugal force created in the centrifuging is hundreds or thousands of times stronger than the gravitational force; therefore centrifuging
• Fig. 2a is a schematic illustration of a centrifuge which is composed of a cylinder 40 to be rotated at a high speed and having a closed wall. The centrifugal force separates from the material supplied into the cylinder 40 the heavy fraction against the wall of the cylinder to a dense layer 42 while the liquid and the lighter material remain as layers 44 of their own on top of the solid material layer.
• Filtering centrifuges in turn are, in a way, combinations of filtering devices and centrifuges (Fig. 2b).
• filtering centrifuges the separation of particles itself takes place by filtering.
• the starting point of the filtering centrifuges as well is a rotating cylinder 50, but unlike a sedimentation centrifuge, it has a porous surface provided with holes, slots or other apertures suitable for the purpose.
• the driving force in the filtering is, however, the hydrostatic pressure created by the centrifugal force, which is why the methods are classified in separation methods based on centrifuging.
• the heavy material is accumulated onto the surface, in this case the perforated surface, of the cylinder and the lighter material closer to the axis of the cylinder.
• the liquid is removed via the apertures in the cylinder 50 and the extractives retain into the solid material layer.
• particles are separated by means of the centrifugal force as in the sedimentation centrifuging.
• the combination apparatus additionally comprise a washing/thickening zone which functions according to the same principle as a filtering centrifuge.
• the method must be continuous as the processes of the industry in this field are continuous and the liquid volumes to be treated are large. Batch- type operation is out of the question.
• the capacity must be high, at least ten litres per second.
• the method must be applicable in the treatment of sludges and suspensions. Also long-fibre suspensions are treated which further raises the requirements set on the apparatus.
• the fibre recovery degree must be high as the fibre is valuable paper manufacture raw material, which cannot be wasted.
• significant extractives retention is not acceptable, either, as expressly a solution is sought by means of which the problems caused by extractives could be avoided in the manufacture of both pulp and paper.
• the apparatus should be able to reach a high final consistency so as not to have to recycle the fibre returned from the apparatus for reuse back to the process via a thickener.
• the decanter centrifuge 60 illustrated in Fig. 3 and discussed for example in patent publication EP-A1 -447742 comprises an outer casing 62, which surrounds the rotating parts of the device and comprises discharge outlets 64 and 66 for the thickened material and the filtrate.
• an outer casing 62 which surrounds the rotating parts of the device and comprises discharge outlets 64 and 66 for the thickened material and the filtrate.
• Inside the outer shell there is a rotating bowl 68, one end 70 of which is in this structure conical and the other end 72 cylindrical.
• Each end of the bowl has been provided with discharge openings 74 and 76. These are located at the end 72 of the bowl 68 having a larger diameter in the end plate 78 of the bowl 68, and at the narrower end 70 directly along the periphery of the casing of the bowl 68.
• the bowl 68 has been supported with bearings 80 at both the ends.
• a screw conveyor 82 has been placed inside the bowl 68, the screw thread of which extends close to the inner wall of the bowl 68.
• the screw conveyor 82 and the bowl 68 have been connected to each other via gears 86 so that a small difference is created between the rotation speed of the screen conveyor 82 and that of the bowl 68.
• the purpose of this difference is to force the screw conveyor 82 to feed the solids separated by the centrifugal force onto the inner surface of the bowl 68 towards the outlet 74 at the narrower end 70 of the bowl 68.
• the decanter centrifuge illustrated in the figure works so that the suspension to be treated is supplied via the pipe 88 to the screw conveyor 82, which rotates at a high speed. From there the liquid shoots out due to the centrifugal force created by the high rotational speed via holes 92 into the bowl 68 and there, further due to the centrifugal force, the heavy solids are separated from the liquid onto the surface of the bowl 68 while the liquid, being lighter, remains further inside.
• the screw conveyor 82 rotating inside the bowl 68 scrapes with it solid material from the surface of the bowl 68 towards the narrower end 70 of the bowl and from there towards the outlet 74 while the liquid flows to the opposite direction, in other words to a direction where the liquid gets further away from the center line of the rotating bowl 68.
• the thickness of the liquid layer in the bowl 68 is determined by the liquid outlets 76, or rather their distance from the inner surface of the bowl 68.
• the liquid is discharged from the bowl via the opposite end compared with the solids.
• other clearly lighter solid material such as in the case of the invention the extractive material particles, are removed with the liquid. In this way the separated fractions are discharged from the apparatus each via their own outlets 64 and 66.
• Decanter centrifuges have been disclosed also in Swedish patent publications 509400 and 501213.
• the basic operation principles of the solutions disclosed in these are of course the same as that of the centrifuge illustrated in Fig. 3. Only for example the feed point of the liquid to be treated may vary which results in a little different flow directions of the fractions in the apparatus.
• the division of the liquid into fractions is performed with a uniform, non-perforated rotating surface.
• the separation portion 96 into which in practise flows only solids separated from the liquid, there is a screen surface 97 through which the finer fraction of the solids is removed from the apparatus to a discharge hopper 98.
• the coarser fraction of the solids is discharged via the end of the apparatus to a discharge chute 99.
• This portion may also be called a solids washing portion.
• the solving of the problems the invention addresses can be started with an apparatus, the characteristic features of which are both that the liquid is divided into fractions by a revolving unbroken surface, and that the revolving speed of the apparatus, more precisely that of the bowl or the cylinder of the apparatus, is high.
• the central acceleration the apparatus develops we have determined it in our experiments. Based on the tests we have performed, the central acceleration should be more than 200 * g, preferably more than 700 * g, most preferably more than 1000 * g.
• a test run was performed with a solids recovery method and a method for separating solids and extractives in a productions scale PGW pulp production plant in connection with a paper mill.
• the wood species were spruce and the filtrate was filtrate from a washing press.
• the bleaching process was ditionite bleaching and the pulp was brought to the washing press directly from a disc filter.
• a bleaching press was not in use.
• the solids recovery apparatus was a decanter centrifuge; the capacity of the decanter centrifuge was informed by the producer of the apparatus to be 20 m 3 /h.
• the length of the centrifuge was 3975 mm, the width 1140 mm and the height 1570 mm.
• Figure 5 illustrates the different degrees of solids recovery at different feed rates as a function of the rotating speed of the decanted cylinder.
• the test apparatus was adjusted to give as high a discharge consistency of the solids as possible. This kind of an adjustment is as such better suited in the concentration of the biological sludge of waste water treatment plants than in the treatment of pulp production waters. By optimising the apparatus the solids recovery degree and the capacity can be improved further.
• the reference number 100 refers to the wood material brought to the process, the material being diluted to a suitable consistency at 102.
• Filtrate from the circulation water tank 104 of the process is used in the dilution.
• the pulp obtained from the dilution is brought to screening 106 and the accepted fraction obtained from the screening is thickened for example with a disc filter 108.
• the purpose of the thickening is both, as is natural, to raise the consistency of the pulp and to remove extractives from the pulp.
• the thickened pulp is reintroduced to dilution 110 where the consistency is adjusted to be suitable for further processing.
• the pulp is brought to a washer 112, which is preferably a press, either a screw or a wire press. After the wash the pulp 114 is transported either directly to the paper mill or to bleaching.
• Figure 6 illustrates also, how the filtrate from the thickener 108, which in this example is disc filter, and the wash filtrate from the washer 112, however, via a filtrate tank 1 16 of its own, are brought to a circulation water tank 104, where filtrates from different sources are mixed with each other.
• a decanter centrifuge 60 has been connected to the process and filtrate obtained from the washer 1 12 is brought from the filtrate tank 1 16 to the decanter centrifuge via a valve 1 18.
• the task of the centrifuge 60 is to recover from the filtrate fibre material suitable for paper production, the material being guided in a flow 120 to pulp 1 14, which is forwarded to further processing, and to separate from the filtrate lipophilic extractives to a separate flow 122.
• Figure 6 further illustrates with the reference number 124 clean fresh water brought to the process to replace the water volume discharged from the process. Water is removed for example with the pulp 1 14 discharged from the process and both from the circulation water tank 104 in the flow 126 and from the filtrate tank 1 16 with the extractives in the flow 122.
• the simulations takes place in a balanced situation when the operation of the process is stable.
• a 'softwood' component is treated as the solid material, lipophilic extractive material both in a water phase and in a solids phase as the 'org' component, and water as the 'water' component.
• the consistency has been determined by dividing the 'softwood' flow by the total flow, in other words the lipophilic extractives have not been calculated as solids.
• Lipophilic extractives only in the water phase can be separated with the water in a press/thickener, the lipophilic extractives in the solid phase move with the solid material.
• the retention of the lipophilic extractives relates to the behaviour of lipophilic extractives in the water phase, only.
• the retained lipophilic extractives remain in the water phase.
• the solids flow is chosen to be 1 kg/s.
• the total volume of lipophilic extractives is known to be 8 mg/g and their share in the water phase is 60 %.
• the water flow is 0.992 kg/s.
• the consistency is 50 % and the total flow rate 2 kg/s.
• the filtrate tank of the press The module used MIXDIV.
• the values of the screening method final consistency 1 %, retention of lipophilic extractives 0 %, recovery degree of solids 60 %, the module used FLOTA2.
• the values of the disc filter final consistency 15 %, retention of lipophilic extractives 30 %, recovery degree of solids 95 %, the module used FLOTA2.
• Figure 7 illustrates the solids losses (%) of the process obtained from a simulation according to Figure 6 as a function of the filtrate volume flowing to the solids recovery (l/kg abs. dry matter) with different solids recovery methods.
• the recovery methods were a decanter centrifuge, a screening method and a disc filter. For comparison, also a case was taken up where solids were not recovered.
• the results indicate that the solids losses with a decanter centrifuge and a disc filter are essentially the same, i.e. less than 10 % compared with a situation where solids were not recovered.
• the solids losses were a little more than one third compared with the situation with no fibre recovery.
• Figure 8 illustrates solids losses (%) of the process obtained from a simulation according to Figure 6 as a function of the filtrate volume discharged from the (l/kg abs. dry pulp) with different process filtrates.
• the process filtrates treated were filtrates from a screw press and a wire press and for comparison so-called clear filtrate of the present technology.
• the amount of solids removed with the filtrate from a screw press is about three times the amount removed by a wire press, and roughly expressed about twenty times the amount removed with a clear filtrate.
• Figure 9 illustrates separation efficiencies of lipophilic extractives (%) as a function of the filtrate volume discharged from the process (l/kg abs. dry pulp) obtained from a simulation according to Figure 6 with different process filtrates.
• a screw press reaches a level of its own. Its separation efficiency very quickly rises over thirty percent and ends up at over fifty percent. The separation efficiency of a wire press rises more slowly, however, reaching in the end a level of close to forty percent.
• Figure 10 illustrates separation efficiencies of lipophilic extractives (%) as a function of the filtrate volume flowing to the solids recovery (l/kg abs. dry pulp) obtained from a simulation according to Figure 6 with different solids recovery methods.
• the recovery methods were the same as in Figure 6.
• the best separation efficiency was reached with a decanter centrifuge or, when solids were not recovered, the screening method was a little worse and the disc filter even a little worse than the screening method.
• Figure 11 illustrates consistencies (%) of the discharged pulp as a function of the filtrate volume flowing to the fibre recovery (l/kg abs. dry pulp) obtained from a simulation according to Figure 6 with different solids recovery methods.
• An interesting feature is that the consistency of the discharging pulp remains practically constant irrespective of the volume of filtrate with all other recovery methods except with the screening method with which the consistency decreased from forty percent to less than 25 percent.
• a process application according to a preferred embodiment of the invention is illustrated in Figure 12.
• the application is a PGW plant (also GW and other processes based on grinding), into which the wood material is brought in the form of logs, which are ground under high pressure.
• the fibre suspension produces as a result of the grinding 142 is transported to a so-called hot loop thickening 144 where filtrate is removed from the suspension.
• the suspension itself continues thickened to a sorting 146 and the filtrate to a hot water tank 148.
• a part of the liquid from the hot water tank 148 is returned to the grinding 142 and a part is taken to a decanter centrifuge 60 where the solids S are recovered from the liquid in the manner described above and can be recycled to the process.
• the extractives E remaining in the liquid phase are discharged from the process separate from the solids S.
• FIG 13 illustrates a process application according to another preferred embodiment of the invention. Also this application relates to a PGW plant (also GW and other processes based on grinding) and resembles closely the application in Figure 12; in the version of Figure 13, only a press 150 has been added after the hot loop thickener 144.
• the filtrate from the press 150 is taken to a filtrate tank 152 from which at least a portion of the filtrate is further taken to decanter centrifuge 60 where the extractive material and the solids to be recovered and to be recycled to the process are separated to form separate flows.
• Figure 14 illustrates a process application according to a third preferred embodiment of the invention.
• This application relates to a pulp manufacturing process portion following a sorting 160. After the sorting 160 the pulp suspension is guided to a thickening 162 where the filtrate is separated and transported to a circulation water tank 164. A portion of the filtrate is returned to the pulp suspension prior to the sorting 160 to dilute the suspension and a portion is guided to the decanter centrifuge 60 where the usable solid material S is separated from the filtrate for recycling to the process, and the extractive material E for removal from the process.
• FIG. 15 illustrates a process application according to a fourth preferred embodiment of the invention.
• This application relates to a thickening and pressing process preceding the bleaching of mechanical or chemi-mechanical pulp.
• a thickening 170 in which filtrate is removed to a circulation water tank 172 in order to raise the consistency.
• the thickened fibre suspension is introduced further to a bleaching press 174, where filtrate is further removed from the suspension.
• the fibre suspension travels from the bleaching press 174 to bleaching 176 and the filtrate from the press 174 to a filtrate tank 178.
• a portion of the filtrate collected to the filtrate tank 178 is transported to dilute the pulp before the thickening 170 and a portion to the decanter centrifuge 60, where the filtrate is divided in the way described above into a fraction containing solids S to be recycled into the process, and into a fraction containing extractives E to be removed from the process.
• Figure 16 illustrates a process application according to a fifth preferred embodiment of the invention suitable for use in connection with any of the processes covered by this invention.
• the decanter centrifuge has been arranged to treat filtrate from a washing press 182 following a bleaching 180.
• a portion of the filtrate of the washing press 182 is guided from the filtrate tank 184 back to the process to be used prior to the press 182 in the dilution of the fibre suspension while a portion flows to the decanter centrifuge 60.
• the solid material S is separated from the filtrate for recycling to the process and the extractives E for removal from the process.
• FIG 17 illustrates a process application according to a sixth preferred embodiment of the invention. It describes a refining process (CTMP or APMP); the fibre suspension obtained after a refining phase 190 of the process is transported to a press 192 in which filtrate is pressed out from the suspension by a know method. The filtrate is guided to a filtrate tank 194 from which at least a portion of the filtrate is guided to a decanter centrifuge 60, which separates from the filtrate the recoverable solids S to a flow of its own to be returned to the process and the extractive material E to a flow to be discharged from the process.
• CTMP refining process
• APMP APMP
• Figure 18 illustrates a process application according to a seventh preferred embodiment of the invention. Also that describes for example a refining process (TMP, CTMP, CMP, APMP and other processes in which the wood raw material is chopped into ships prior to at least a partial mechanical defiberizing), in which a first press 200 is arranged to treat the chips. It has been found advantageous to recover already at this stage at least part of the filtrate via a filtrate tank 202 to the decanter centrifuge 60 in order to separate from each other the extractives E, and the solids S to be returned to the process.
• TMP refining process
• CTMP CMP
• APMP partial mechanical defiberizing
• Figure 19 illustrates a process application according to an eighth preferred embodiment of the invention, suitable for use in connection with any mechanical or chemi-mechanical process.
• the figure illustrates how an apparatus 212 has been disposed after a filtrate tank 210 and prior to a decanter centrifuge 60; the apparatus 212 can be for example a screen, a separator, a fractionator, a thickener or a corresponding device, which is intended to have an appropriate influence on the filtrate to be introduced into the decanter centrifuge 60.
• One possibility is for example a thickener with which water is separated from the filtrate flowing to the decanter centrifuge whereby the size of the centrifuge required can be reduced as the liquid flow to be treated decreases.
• the process described also creates a situation where, when the apparatus 212 is for example a disc filter (the consistency of the incoming pulp for example 0.3 %) whereby the extractives readily remain in the suspension thickened by the disc filter, there are in the filtrate of the disc filter (consistency 0 %) relatively small amounts of extractives as they accumulate into the cake (consistency 0,6 %) of the disc filter which is transported further to the centrifuge. Then, although the centrifuge can be fairly small in size the liquid flow it treats contains remarkable amounts of extractives.
• Another altemative is an apparatus separating fibre fractions with which a portion of the fibre can be removed before the centrifuge.
• the processed described above can include also washers, which in this context are devices in which the consistency of the pulp fed into the device and that of the pulp discharged from the device are essentially the same.
• the filtrate of the washer is analogous with the filtrate of a thickener or a press or a corresponding device, which removes liquid from the pulp, and thus it can be treated in a decanter centrifuge or a corresponding device for separating extractives from the usable solids.
• the decanter centrifuge or the corresponding device 60 is always preceded by a filtrate tank, in suitable conditions this can be omitted altogether, in which case there is a pipeline extending from a press or a corresponding device to the decanter centrifuge or a corresponding device.
• the filtrate tank can be replaced by two or even three filtrate tanks if the preceding liquid removing device allows separating several types of filtrates (for example cloudy, clear, super clear).
• each portion of the above filtrates can be used in the way desired (for example as dilution liquid, as liquid to be treated in a decanter centrifuge, as waste water to be transferred to a channel, etc.)

Landscapes

• Paper (AREA)
• Extraction Or Liquid Replacement (AREA)
• Treatment Of Liquids With Adsorbents In General (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=8561155

Family Applications (1)

Country Status (6)

Families Citing this family (3)

Family Cites Families (4)

• 2001
  • 2001-05-09 FI FI20010967A patent/FI110580B/fi not_active IP Right Cessation
• 2002
  • 2002-05-07 EP EP02722318A patent/EP1392913B1/de not_active Expired - Lifetime
  • 2002-05-07 CA CA002446407A patent/CA2446407C/en not_active Expired - Fee Related
  • 2002-05-07 AT AT02722318T patent/ATE435328T1/de not_active IP Right Cessation
  • 2002-05-07 DE DE60232791T patent/DE60232791D1/de not_active Expired - Lifetime
  • 2002-05-07 WO PCT/FI2002/000391 patent/WO2002090647A1/en not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events