[go: up one dir, main page]

WO1991005912A1 - A method and device for the production of cellulose pulp of improved quality - Google Patents

A method and device for the production of cellulose pulp of improved quality Download PDF

Info

Publication number
WO1991005912A1
WO1991005912A1 PCT/SE1990/000648 SE9000648W WO9105912A1 WO 1991005912 A1 WO1991005912 A1 WO 1991005912A1 SE 9000648 W SE9000648 W SE 9000648W WO 9105912 A1 WO9105912 A1 WO 9105912A1
Authority
WO
WIPO (PCT)
Prior art keywords
hydrocyclone unit
βecond
pump
flow
headbox
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.)
Ceased
Application number
PCT/SE1990/000648
Other languages
French (fr)
Inventor
Nils Anders Lennart Wikdahl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=8203268&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=WO1991005912(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Individual filed Critical Individual
Priority to JP3500294A priority Critical patent/JPH0781240B2/en
Priority to BR909006945A priority patent/BR9006945A/en
Publication of WO1991005912A1 publication Critical patent/WO1991005912A1/en
Priority to FI912765A priority patent/FI102302B1/en
Priority to NO912197A priority patent/NO178348C/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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
    • 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
    • D21D5/18—Purification of the pulp suspension by mechanical means; Apparatus therefor with the aid of centrifugal force
    • D21D5/24—Purification of the pulp suspension by mechanical means; Apparatus therefor with the aid of centrifugal force in cyclones
    • 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

Definitions

  • the present invention relates to a method and a device for the treatment of suspensions of cellulose fibers, which are to be cleaned and concentrated, wherein the cleaning also encompasses the elimination of light impurities.
  • hydrocyclone ⁇ Cleaning out light impurities by means of hydrocyclone ⁇ is also previously known, particularly in the treatment of recycled paper, which often contains significant amounts of waste plastic and ink etc.
  • the hydrocyclones normally used in this case are dimensioned and disposed in such a way that the base fraction contains the light impurities and the apex fraction the major portion of the input cellolose fibers.
  • Hydrocyclones for this purpose are also known in which both fractions are taken out at the same end through separate outlets.
  • the first mentioned type of ydrocyclone is referred to below as an A-cyclone, while the second is referred to as a B-cyclone.
  • the suspension produced by whatever method is first diluted to be able to be screened and/or cyclontreated, whereafter the cleaned suspension is thickened to be able to be intermediately stored.
  • This thickening is normally done in open thick ⁇ eners.
  • This thickening, intermediate storage and dilution involves extra costs, which can be eliminated by concentrating the pulp coming from the cycloning step and directly leading it to the wet machine, particularly by using the same pump for the primary cycloning step and a closed thickener working under pressure, as disclosed in Swedish Lay-Open Print 8305036-9.
  • one purpose of the present invention is to provide an improved system for manufacturing paper pulp of good quality, especially as regards elimination of impurities, both in the form of heavy and light particles.
  • Light particles are meant to include not only particles of low density, but also particles which due to their shape perform as lighter than cellulose fibers in hydrocyclone ⁇ ).
  • Another purpose is to provide a system which eliminates the need for thickening for intermediate storage of al ⁇ ready cleaned pulp ⁇ u ⁇ pen ⁇ ion.
  • the invention provides an essentially continous process which performs, in one sequence, cleaning, concentration and final treatment in a wet machine or paper machine.
  • One particular advantage of the invention i ⁇ the ⁇ yner- getic effect achieved by the combination of the functions of thickening and cleaning from light impurities, prefer ⁇ ably whilst simultaneously eliminating an intermediate storage ⁇ tep and a diluting step.
  • Hydrocyclone ⁇ must of cour ⁇ e be 5 operated with an e ⁇ sentially constant flow of liquid, and the output consistency is determined by the consistency of the pulp flow supply.
  • the flow to the wet machine or paper machine can then be additionally varied by a feedback which feeds a controllable portion of the output flow to -JO the input side of the cleaning system.
  • hydrocyclones function best if the liquid flows and pressure ratios are kept rather constant at the rated values.
  • the feedback can be to a point prior to the con ⁇ sistency control in connection with a first dilution, thus 0 keeping the consistency of the ⁇ u ⁇ pen ⁇ ion to the headbox constant and reducing the flow to the headbox.
  • the invention will now be described with reference to a non-limiting example, shown schematically in diagram form 5 in the drawing.
  • the schematic figure shows an example of a plant function ⁇ ing in accordance with the invention.
  • the major portion of the fiber material passing through it flows from a conven ⁇ tional silo l to a wet machine or paper machine 9 along a main path drawn a ⁇ a thick line.
  • the suction side of the pump 3 i ⁇ connected to the ⁇ ilo 2. and it receive ⁇ diluting water from the pump 12 via the valve 300, which i ⁇ controlled by the ⁇ en ⁇ or 301, which ⁇ en ⁇ e ⁇ the con ⁇ i ⁇ tency of the suspension exiting from the pressure side of the pump 3.
  • the con ⁇ i ⁇ tency i ⁇ controlled thereby to 2.5*.
  • the flow of the suspension supplied i ⁇ led through a valve 400 under the control of a flow ⁇ en ⁇ or 401 at a de ⁇ ired level.
  • the flow of fiber ⁇ through the valve 40 ⁇ i ⁇ thu ⁇ kept constant.
  • the pump 4 a centri ⁇ fugal pump, provide ⁇ an e ⁇ entially constant flow, and the 5 pres ⁇ ure on the ⁇ uction ⁇ ide i ⁇ determined by the level in the white water tank 10. the level of which i ⁇ kept con- ⁇ tant in a known manner.
  • the pump 4 a ⁇ long as its coun- terpre ⁇ ure i ⁇ ⁇ table, give ⁇ a predetermined flow with a con ⁇ i ⁇ tency determined by the amount of fiber ⁇ per unit of 0 time which passes through the valve 400.
  • the suspension thus diluted is led through a ⁇ creen 5, which i ⁇ primarily intended to eliminate ⁇ crap particle ⁇ and other larger particle ⁇ , which could damage the cyclone ⁇ , to a multi-hydrocyclone unit 6 with A-cyclone ⁇ , o the base fraction of which is conducted further.
  • the con ⁇ i ⁇ tency of the ba ⁇ e fraction will be 0.45*, i.e. somewhat thinner than the suspension supplied.
  • This consi ⁇ tency is suitable for the following wet 0 or paper machine 9, to the headbox 8 of which the ⁇ u ⁇ - pen ⁇ ion i ⁇ conducted via a valve 800, controlled by a ⁇ en ⁇ or 801, in thi ⁇ ca ⁇ e a pressure ⁇ en ⁇ or.
  • the headbox thus receives the su ⁇ pen ⁇ ion at a controlled pre ⁇ ure.
  • the ⁇ en ⁇ or 801 can be a level ⁇ en ⁇ or or a flow ⁇ en ⁇ or.
  • Recovery unite are connected to the two multi-hydro- cyclone unite 6 and 7.
  • the recovery units are shown here a ⁇ cascade coupled units with individual pumps at the inlets and with the outlets connected to a common level in the tank 10. Although only two step ⁇ in each unit have been ⁇ hown, the number of ⁇ teps i ⁇ determined by the de ⁇ ired degree of recovery and purification.
  • the recovery units to the unit 6 consist of A-cyclones, while the recycling units to unit 7 are B-cyclones.
  • the number of ⁇ tep ⁇ in the recycling from unit 7 i ⁇ po ⁇ itively affected. as i ⁇ the number of individual cyclones in the units, if the latter are constructed in accordance with Swedish patent application 8802580-4.
  • the unit 7 provides both a cleaning from light impurities and a thickening of the suspension thus cleaned, which combination i ⁇ the great advantage of the invention.
  • Thi ⁇ thickening can be done in different degree ⁇ depending on the cyclone dimensions, the pre ⁇ ure drop and the di ⁇ tribution of apex and ba ⁇ e flow ⁇ of the incoming suspension.
  • the thickening factor which always exceeds 1, and in thi ⁇ example i ⁇ 3.33, can be increa ⁇ ed to 5 for example, if ⁇ o required, and thi ⁇ can be done without negatively effecting the ⁇ eparation of light impurities; on the contrary, the separation effect will tend to increa ⁇ e.
  • the fiber content in the ba ⁇ e fraction may thereby increa ⁇ e, ⁇ o that the proce ⁇ ing work in the recovery unite increa ⁇ e ⁇ , but thi ⁇ can be dealt with by using hydrocyclones according to the Swedish patent application 8802580-4.
  • the above-mentioned thickening is a result of ⁇ eparation of water and fiber ⁇ .
  • the degree of thickening in a hydro- cyclone i ⁇ determined by the effectivene ⁇ of thi ⁇ ⁇ epara ⁇ tion. in order to achieve a high degree of thickening, the hydrocyclone i ⁇ made with a smaller ba ⁇ e opening than the apex opening.
  • the conical ⁇ epara- tion chamber ⁇ hould have a large ⁇ t diameter of le ⁇ than 125 mm and preferably le ⁇ than 100 mm. Furthermore, the diameter of the ba ⁇ e opening ⁇ hould be le ⁇ than a fifth of the large ⁇ t diameter of the separation chamber.
  • hydrocyclone ⁇ ⁇ hould be operated with predetermined liquid flow ⁇ .
  • thi ⁇ i ⁇ the case with the headbox of a wet o machine or paper machine, where the flow, pre ⁇ ure and consistency may need to be varied.
  • the con ⁇ i ⁇ tency, at con ⁇ tant flow can be controlled by controlling the flow and consi ⁇ tency of the ⁇ u ⁇ pen ⁇ ion ⁇ upplied via the valve 400.
  • the flow to the headbox 8 can be controlled by a return line 13 with the valve 130 controlled by a pre ⁇ ure ⁇ en ⁇ or 131.
  • Thi ⁇ return line 13 can, in accordance with the first embodiment, open into the ⁇ uction ⁇ ide of the pump 4, which will cause the fiber flow to the headbox 8 to be unchanged while the con ⁇ i ⁇ tency i ⁇ changed.
  • control measures within the scope of the invention to vary for example the degree of thickening in the ⁇ y ⁇ tem.
  • a ⁇ ingle main pump 4 pump ⁇ the diluted suspension to the units 6 and 7 coupled in series and then to the headbox 8.
  • the ⁇ e pre ⁇ ure drop ⁇ are essentially a function of the flow.
  • control of the valves 800 and 130 must be done in ⁇ uch a manner that the operating condition ⁇ for the multi-hydro ⁇ cyclone unite are not affected negatively.
  • the main pump 4 - ⁇ a centrifugal pump, driven at essentially con ⁇ tant rotational ⁇ peed, with falling pre ⁇ ure head as flow increases.
  • the ⁇ y ⁇ tem i ⁇ de ⁇ igned ⁇ o that at the rated flow the pre ⁇ ure head i ⁇ ⁇ ufficient for the pre ⁇ ure drop ⁇ in the multi-hydrocyclone units 6 and 7 and the valve 800 at a normal work point, and controlling within reasonable limits of the flow through the valve 800 to keep the pressure or the level in the headbox 8 does not involve any appreciable disruption.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
  • Silicon Compounds (AREA)
  • Materials For Medical Uses (AREA)
  • Magnetic Record Carriers (AREA)
  • Particle Formation And Scattering Control In Inkjet Printers (AREA)
  • Bakery Products And Manufacturing Methods Therefor (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)

Abstract

In a process and a device, a cellulose suspension of thin consistency, the consistency and flow rate of which is known, is conducted to the suction side of a main pump (4), to the pressure side of which there are coupled in sequence a first multi-hydrocyclone unit (6) for cleaning out heavy impurities, a second multi-hydrocyclone unit (7) for cleaning out light impurities, and a headbox (8) for a wet machine or paper machine (9). This provides, on one hand, cleaning and pulp or paper production uninterrupted by intermediate storage, and on the other hand a thickening of the pulp in the second multi-hydrocyclone unit from a suitable consistency for cleaning to a thicker consistency suitable for spreading on a wire or the like.

Description

A method and device for the production of cellulose pulp of improved quality
The present invention relates to a method and a device for the treatment of suspensions of cellulose fibers, which are to be cleaned and concentrated, wherein the cleaning also encompasses the elimination of light impurities.
The cleaning of cellulose suspensions from heavy im¬ purities, such as sand, bark and short shiveβ, is now normally done in hydrocycloneβ, in which the impurities are taken out in the apex fraction and the purified suspension in the base fraction, such cleaning presupposes a low fiber content, 0.1-3*. preferably 0.2-2*.
Cleaning out light impurities by means of hydrocycloneβ is also previously known, particularly in the treatment of recycled paper, which often contains significant amounts of waste plastic and ink etc. The hydrocyclones normally used in this case are dimensioned and disposed in such a way that the base fraction contains the light impurities and the apex fraction the major portion of the input cellolose fibers. Hydrocyclones for this purpose are also known in which both fractions are taken out at the same end through separate outlets.
The first mentioned type of ydrocyclone is referred to below as an A-cyclone, while the second is referred to as a B-cyclone.
Since hydrocyclones are not perfect separators, recycling units are always required for economic reasons, which recover cellulose fibers from the reject material. Such recovering is previously known. As regards recycling with B-cycloneβ, reference is made to Swedish patent applica- tion 8802580-4 from 8 July 1988, which describes hydro¬ cyclones particularly suited for such recycling.
in plants presently used for manufacturing paper and market pulp, it is usual that the suspension produced by whatever method (cooking, defibration, bleaching, beating of recycled paper) is first diluted to be able to be screened and/or cyclontreated, whereafter the cleaned suspension is thickened to be able to be intermediately stored. This thickening is normally done in open thick¬ eners. In order to thereafter be able to conduct the pulp to a wet machine it must be diluted once again, as a rule to a concentration which is higher than that used for the cleaning step. This thickening, intermediate storage and dilution involves extra costs, which can be eliminated by concentrating the pulp coming from the cycloning step and directly leading it to the wet machine, particularly by using the same pump for the primary cycloning step and a closed thickener working under pressure, as disclosed in Swedish Lay-Open Print 8305036-9.
As mentioned aboved, however, there is an increasing need for removal of light impurities, especially plastic, and this applies not only to recycled paper but also to wood, particularly from populated areas, which contains in¬ creasing amounts of plastic impurities. Plastic particles can also come in during production in the plant. Even small amounts of these impurities can present difficulties in paper production, stripes in the paper web can appear for example when coating.
one purpose of the present invention is to provide an improved system for manufacturing paper pulp of good quality, especially as regards elimination of impurities, both in the form of heavy and light particles. (Light particles are meant to include not only particles of low density, but also particles which due to their shape perform as lighter than cellulose fibers in hydrocycloneβ).
Another purpose is to provide a system which eliminates the need for thickening for intermediate storage of al¬ ready cleaned pulp βuβpenβion. instead, the invention provides an essentially continous process which performs, in one sequence, cleaning, concentration and final treatment in a wet machine or paper machine.
These and other purposes and advantageβ are achieved according to the invention by the proceββ according to claim 1 and by a device according to claim 8.
One particular advantage of the invention iβ the βyner- getic effect achieved by the combination of the functions of thickening and cleaning from light impurities, prefer¬ ably whilst simultaneously eliminating an intermediate storage βtep and a diluting step.
What makes the invention possible iβ the fact that the suspension fraction coming from the apex in a hydrocyclone designed for eliminating lighter impurities has a conβiβt- ency which iβ increased in relation to that of the βus- pension supplied, since much water accompanies the light impurities in the base fraction.
A particularly high consistency can be achieved, with very good separation of light impurities, if one can accept that some cellulose fibres will accompany the base fraction, whereby the recovery is simplified by reducing the number of recycling stepβ by uβing hydrocycloneβ of the type described in Swedish patent application 8802580-4 (not yet publicly available).
According to the invention, it is poββible to achieve a consistency of between 1 and 3* after combined cleaning of the light impurities and thickening, which is a suit¬ able starting consistency for many types of wet machines and paper machines. Hydrocycloneβ must of courβe be 5 operated with an eβsentially constant flow of liquid, and the output consistency is determined by the consistency of the pulp flow supply. The flow to the wet machine or paper machine can then be additionally varied by a feedback which feeds a controllable portion of the output flow to -JO the input side of the cleaning system.
It is suitable to provide the white water tank of the wet or paper machine with a spillway to keep the water level constant, and to take the necessary diluting water from 5 there for the process.
As a rule, hydrocyclones function best if the liquid flows and pressure ratios are kept rather constant at the rated values. However, in different operating situations it can o be necessary to vary the flow to a wet machine or paper machine. It is therefore suitable to arrange a diversion of the treated suβpenβion, which returns the unused but cleaned and concentrated βuspension. This recycling can be done to a point immediately in front of the main pump, 5 without changing the fiber flow to the wet machine or paper machine, but with the result that the consistency of the βuspenβion to the headbox will be increased. Alterna¬ tively, the feedback can be to a point prior to the con¬ sistency control in connection with a first dilution, thus 0 keeping the consistency of the βuβpenβion to the headbox constant and reducing the flow to the headbox.
The invention will now be described with reference to a non-limiting example, shown schematically in diagram form 5 in the drawing. The schematic figure shows an example of a plant function¬ ing in accordance with the invention. The major portion of the fiber material passing through it flows from a conven¬ tional silo l to a wet machine or paper machine 9 along a main path drawn aβ a thick line. The pulp with a conβiβt- ency of 10-12* iβ diluted in the lower portion of the βilo
1 to about 3.5*, and is diluted at the input side of a pump 103 to a controlled consiβtency of 3.0* and iβ then led to a silo 2, where the level iβ kept constant. The diluting water is taken via a pump 12 from the white water of the wet or paper machine. The person skilled in the art will understand how the level and consiβtency in the βilo
2 will be controlled and therefore it iβ βufficient to state that the dilution is controlled by actuating the valves 100 and 101 by the sensor 102 and the level by the level βenβor 200, which controls the speed regulator 104 to the pump 103. 105 iβ a control unit which openβ the valves 100 and 101 in parallel and controls the flow therethrough in a predetermined ratio. In the silo 2, there iβ thereby achieved a constant level and a conβtant conβiβtency for the suspension.
The suction side of the pump 3 iβ connected to the βilo 2. and it receiveβ diluting water from the pump 12 via the valve 300, which iβ controlled by the βenβor 301, which βenβeβ the conβiβtency of the suspension exiting from the pressure side of the pump 3. The conβiβtency iβ controlled thereby to 2.5*. The flow of the suspension supplied iβ led through a valve 400 under the control of a flow βenβor 401 at a deβired level. The flow of fiberβ through the valve 40~ iβ thuβ kept constant.
A controlled flow of suspension with a controlled con¬ βiβtency (fiber concentration) iβ thuβ led to the βuction βide of the pump 4. For the present, one can disregard the line 13, which refers to a particular aspect of the invention which will be described in more detail below. The pump 4, a centri¬ fugal pump, provideβ an eββentially constant flow, and the 5 presβure on the βuction βide iβ determined by the level in the white water tank 10. the level of which iβ kept con- βtant in a known manner. The pump 4, aβ long as its coun- terpreββure iβ βtable, giveβ a predetermined flow with a conβiβtency determined by the amount of fiberβ per unit of 0 time which passes through the valve 400. With the valueβ according to the example, a conβiβtency of 0.5* iβ attain¬ ed on the preββure βide of the pump 4, which iβ a suitable value for cycloning, even though thinner and thicker con¬ sistencies are possible to work with. 5
The suspension thus diluted is led through a βcreen 5, which iβ primarily intended to eliminate βcrap particleβ and other larger particleβ, which could damage the cycloneβ, to a multi-hydrocyclone unit 6 with A-cycloneβ, o the base fraction of which is conducted further. The conβiβtency of the baβe fraction will be 0.45*, i.e. somewhat thinner than the suspension supplied. This baβe fraction iβ moved on without intermediate pumping to a multi-hydrocyclone unit 7 with B-cycloneβ, where the fiber 5 iβ removed aβ an apex fraction, while the lighter par¬ ticles go into the baβe fraction, in thiβ apex fraction, the cellulose fiberβ are enriched to a higher conβiβtency, in the example to 1.5*, thuβ thickened by a factor of 3.33. This consiβtency is suitable for the following wet 0 or paper machine 9, to the headbox 8 of which the βuβ- penβion iβ conducted via a valve 800, controlled by a βenβor 801, in thiβ caβe a pressure βenβor. The headbox thus receives the suβpenβion at a controlled preββure. If βo deβired, the βenβor 801 can be a level βenβor or a flow βenβor.
Recovery unite are connected to the two multi-hydro- cyclone unite 6 and 7. The recovery units are shown here aβ cascade coupled units with individual pumps at the inlets and with the outlets connected to a common level in the tank 10. Although only two stepβ in each unit have been βhown, the number of βteps iβ determined by the deβired degree of recovery and purification. The recovery units to the unit 6 consist of A-cyclones, while the recycling units to unit 7 are B-cyclones. The number of βtepβ in the recycling from unit 7 iβ poβitively affected. as iβ the number of individual cyclones in the units, if the latter are constructed in accordance with Swedish patent application 8802580-4.
in the example, the unit 7 provides both a cleaning from light impurities and a thickening of the suspension thus cleaned, which combination iβ the great advantage of the invention. Thiβ thickening can be done in different degreeβ depending on the cyclone dimensions, the preββure drop and the diβtribution of apex and baβe flowβ of the incoming suspension. The thickening factor, which always exceeds 1, and in thiβ example iβ 3.33, can be increaβed to 5 for example, if βo required, and thiβ can be done without negatively effecting the βeparation of light impurities; on the contrary, the separation effect will tend to increaβe. The fiber content in the baβe fraction may thereby increaβe, βo that the proceββing work in the recovery unite increaβeβ, but thiβ can be dealt with by using hydrocyclones according to the Swedish patent application 8802580-4.
The above-mentioned thickening is a result of βeparation of water and fiberβ. The degree of thickening in a hydro- cyclone iβ determined by the effectiveneββ of thiβ βepara¬ tion. in order to achieve a high degree of thickening, the hydrocyclone iβ made with a smaller baβe opening than the apex opening. For the βeparation work, the conical βepara- tion chamber βhould have a largeβt diameter of leββ than 125 mm and preferably leββ than 100 mm. Furthermore, the diameter of the baβe opening βhould be leββ than a fifth of the largeβt diameter of the separation chamber.
5
The main flow of fiberβ has now been explained. The return flowβ from the recycling βtepβ go through the line 11' back to the suction side of the pump 4. Thiβ eanβ, that if the line 13 were not there, the entire flow of fiberβ, 0 under βtability conditionβ, coming in via the valve 400, would be fed out to the headbox 8. The flow iβ then determined by the capacity of the pump 4 and by the flow-offβ, determined by the normally conβtant preββure ratios, in the apex fraction of unit 6 and in the baβe 5 fraction of unit 7.
For optimal operation, hydrocycloneβ βhould be operated with predetermined liquid flowβ. However, it iβ not certain that thiβ iβ the case with the headbox of a wet o machine or paper machine, where the flow, preββure and consistency may need to be varied. The conβiβtency, at conβtant flow, can be controlled by controlling the flow and consiβtency of the βuβpenβion βupplied via the valve 400. The flow to the headbox 8 can be controlled by a return line 13 with the valve 130 controlled by a preββure βenβor 131. Thiβ return line 13 can, in accordance with the first embodiment, open into the βuction βide of the pump 4, which will cause the fiber flow to the headbox 8 to be unchanged while the conβiβtency iβ changed.
In accordance with a second embodiment, drawn with daβhed lineβ in the Figure, the return flow iβ effected via a line 13' back to a point prior to the pump 3, in thiβ caβe upβtrea of the dilution control valve 300, but in any caβe to a point upstream of the consiβtency and flow control which determineβ the fiber flow βupplied to the βuction βide of the pump 4. controlling the liquid flow to the headbox 8 by means of the valve 130 does not effect the conβiβtency of the suspension βupply.
The invention haβ now been deβcribed on the basis of a non-limiting example, from which it is clear that βuch a βyβtem can be controlled within wide limite. Even if the flow capacity for the cyclone equipment iβ given by the deβign, it iβ possible to vary within wide limits the capacity of the pulp flow and the conβiβtency of the βus- penβion outflow.
As mentioned, it iβ alβo possible by designing control measures within the scope of the invention to vary for example the degree of thickening in the βyβtem.
One βhould note in particular that a βingle main pump 4 pumpβ the diluted suspension to the units 6 and 7 coupled in series and then to the headbox 8. In a representative example, the presβure drop between the inlet and the baβe in a A-cyclone iβ 1 bar and the preββure drop in a
B-cyclone between the inlet and the apex iβ 1.5 bar. Theβe preββure dropβ are essentially a function of the flow. The pump 4 iβ dimenβioned βo that it can both compenβate theβe preββure dropβ and produce βufficient preββure to the headbox 8.
control of the valves 800 and 130 must be done in βuch a manner that the operating conditionβ for the multi-hydro¬ cyclone unite are not affected negatively. The main pump 4 -β a centrifugal pump, driven at essentially conβtant rotational βpeed, with falling preββure head as flow increases. The βyβtem iβ deβigned βo that at the rated flow the preββure head iβ βufficient for the preββure dropβ in the multi-hydrocyclone units 6 and 7 and the valve 800 at a normal work point, and controlling within reasonable limits of the flow through the valve 800 to keep the pressure or the level in the headbox 8 does not involve any appreciable disruption. Major changes in the preββure drop over the valve 800 cannot be tolerated, however, βince the working conditions for the unite 6 and 7 would be adversely affected. In order to make signi¬ ficant changes in the feed flow to the box 8, there must therefore be a diverβion via the shunt valve 130 so that the preββure on the βuβpenβion can be kept reasonably constant. The shunt valve 130 can then either be control- led manually with reference to a manometer or can be preββure controlled in the manner βhown in the drawing.
The variouβ controls in the drawing have been βhown aβ mutually independent local controlβ. It will be under- βtood, however, that βuch controlβ can be effected by a common computer.

Claims

1. Proceββ for manufacturing celluloβe pulp with improved quality propertieβ, eβpecially aβ regardβ the content of light, βolid impurities such as particleβ of plaβtic and the like, characterized in that a fiber βuβpenβion of low conβiβtency iβ cauβed by a main pump (4) to paββ through a firβt multi-hydrocyclone unit (6) to separate out heavy particles and a second multi-hydrocyclone unit (7) in¬ cluded in the βame pump circuit for βeparating out light particleβ at the βame time aβ the pulp conβiβtency iβ made higher during treatment in the βecond multi-hydrocyclone unit (7), and that at leaβt a portion of the pulp βuβpen¬ βion thuβ treated iβ thereafter conducted directly without intermediate pumping to the headbox (8) of a wet machine or paper machine.
2. Process according to claim l, characterized in that the βuβpenβion conducted to the wet machine or paper machine passes through a controllable valve (800), which iβ con¬ trolled by a βenβor (801) for preββure, flow or level in the head box (8) of the wet machine or paper machine.
3. Proceββ according to claim 1, characterized in that a portion of the flow which emergeβ cleaned from the βecond multi-hydrocyclone unit (7) iβ recycled for intake up- βtream of the main pump (4).
4. Proceββ according to claim 3, characterized in that the recycled flow iβ controlled by meanβ of a valve (130) to achieve the deβired preββure for the cleaned βuβpenβion coming from thiβ βecond multi-hydrocyclone unit.
5. Proceββ according to claim 3, characterized in that the reintroduction iβ arranged at the βuction βide of the main pump (4) .
6. Process according to claim 3, characterized in that the reintroduction is arranged to a diluting device (300) upβtreamβ of the βuction βide of the main pump (4).
7. Proceββ according to claim 1, characterized in that to the βuction βide of the main pump (4) by means of a βecond pump (3) there iβ pumped a βuβpenβion which iβ controlled aβ to itβ flow rate and conβiβtency, the βuction βide of said main pump (4) being coupled to a level regulated tank (10) included in the white water βyβtem of the wet machine or paper machine, dilution being effected with white water therefrom.
8. Proceββ according to claim l, characterized in that the βecond multi-hydrocyclone unit iβ provided with hydro¬ cycloneβ with conical βeparation chamberβ with a greateβt diameter of leββ than 125 mm and preferably leββ than
100 mm, and with a baβe opening diameter which iβ leββ than a fifth of the largeβt diameter of the βeparation chamber and an apex opening which is greater than the baβe opening.
9. Device for manufacturing cellulose pulp with improved quality properties, particularly aβ regards the content of light, solid impurities βuch aβ particleβ of plaβtic and the like, characterized by the combination of a pump (4), a firβt multi-hydrocyclone unit (6) for βeparating out heavy particleβ, a βecond multi-hydrocyclone unit (7) for βeparating out light particleβ, and the headbox (8) of a wet machine or paper machine (9) coupled in βerieβ with each other, said βecond multi-hydrocyclone unit βerving at the βame time aβ a means for thickening the cleaned suspension.
10. Device according to claim 9, characterized by a con¬ trollable valve (800) which is coupled between the βecond multi-hydrocyclone unit (7) and the headbox, and meanβ (801) for βensing and, by actuating the valve (800), con¬ trolling presβure. flow or the level in the headbox.
11. Device according to claim 9 or 10, characterized by a βhunt line (13, 13') which, for diverting βuβpenβion, iβ connected at a diverβion point between the second multi- -hydrocyclone unit (7) and the headbox (8) and leads to an introduction point which is located upstream of βaid pump (4).
12. Device according to claim 11, characterized in that in the shunt line (13, 13') there is a valve (130).
13. Device according to claim 12, characterized by a control device (131) which iβ diβpoβed to control the valve (130) in reβponβe to the preeβure at βaid diverβion point.
14. Device according to claim 11, characterized in that βaid βhunt line (13, 13') leadβ to a diluting device diβpoβed upβtream of the pump (4).
15. Device according to claim 9, characterized in that the βecond multi-hydrocyclone unit iβ made of hydrocycloneβ with conical βeparation chamberβ with a largeβt diameter of at most 125 mm, preferably at most 100 mm, and with the baβe opening and an apex opening, the baβe opening dia¬ meter being leββ than a fifth of the largeβt diameter of the βeparation chamber and the apex opening being larger than the baβe opening.
PCT/SE1990/000648 1989-10-10 1990-10-09 A method and device for the production of cellulose pulp of improved quality Ceased WO1991005912A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
JP3500294A JPH0781240B2 (en) 1989-10-10 1990-10-09 Method and apparatus for producing improved quality cellulose pulp
BR909006945A BR9006945A (en) 1989-10-10 1990-10-09 PROCESS AND APPARATUS FOR THE MANUFACTURE OF CELLULOSE PULP WITH PERFECT QUALITY PROPERTIES
FI912765A FI102302B1 (en) 1989-10-10 1991-06-07 Method and arrangement for production of pulp with improved quality properties
NO912197A NO178348C (en) 1989-10-10 1991-06-07 Method and apparatus for producing cellulose pulp with improved quality properties

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE89850341.2 1989-10-10
EP89850341A EP0422314B1 (en) 1989-10-10 1989-10-10 A method and device for the production of cellulose pulp of improved quality

Publications (1)

Publication Number Publication Date
WO1991005912A1 true WO1991005912A1 (en) 1991-05-02

Family

ID=8203268

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1990/000648 Ceased WO1991005912A1 (en) 1989-10-10 1990-10-09 A method and device for the production of cellulose pulp of improved quality

Country Status (10)

Country Link
EP (1) EP0422314B1 (en)
JP (1) JPH0781240B2 (en)
AT (1) ATE104382T1 (en)
BR (1) BR9006945A (en)
CA (1) CA2042366C (en)
DD (1) DD296722A5 (en)
DE (2) DE68914666T2 (en)
ES (1) ES2023626T3 (en)
NO (1) NO178348C (en)
WO (1) WO1991005912A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998011297A1 (en) * 1996-09-16 1998-03-19 Alfa Laval Ab A method and a plant for treating of a contaminated pulp suspension
WO1998011296A1 (en) * 1996-09-16 1998-03-19 Alfa Laval Ab Method and plant for treating a contaminated pulp suspension
US5753083A (en) * 1995-06-27 1998-05-19 Voith Sulzer Papiermaschinen Gmbh Hydraulic support arrangement for a shoe press device
WO2003016617A1 (en) * 2001-08-15 2003-02-27 Metso Paper, Inc. Headbox of a paper machine or equivalent
RU2708110C1 (en) * 2019-04-09 2019-12-04 Николай Васильевич Байкин Fibrous materials sorting device

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9317817D0 (en) * 1993-08-27 1993-10-13 Wiggins Teape Group The Ltd Papermaking process and apparatus for use therewith
FI103734B (en) * 1997-11-11 1999-08-31 Ahlstrom Machinery Oy Method and plant for the treatment of fiber suspension
FI112806B (en) 2001-03-09 2004-01-15 Metso Paper Inc A method for controlling the quality of a pulp
DE10358567A1 (en) * 2003-12-15 2005-09-08 Nordland Papier Gmbh Method and device for treating a pulp
CN110409212B (en) * 2019-07-19 2021-09-03 王洲 Sandwich type hand towel and production process thereof

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0090928A2 (en) * 1982-04-05 1983-10-12 CLARK & VICARIO CORPORATION Multiple hydrocyclone apparatus
WO1986003143A1 (en) * 1984-11-28 1986-06-05 Noel Carroll Cyclone separator
DE3722440A1 (en) * 1986-07-10 1988-01-14 N Proizv Ob Krachmaloproduktam Multi-cyclone system

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3912579A (en) * 1969-06-04 1975-10-14 Bergstrom Paper Co Reverse cleaning and de-inking of paper stock
USRE29472E (en) * 1971-09-29 1977-11-15 Clark & Vicario Corporation Conduit system for conveying fibrous stock from deaerator chamber to headbox in papermaking machine
US4312701A (en) * 1980-11-07 1982-01-26 Hydro-Thermal Corporation Method for defibrating waste paper and dispersing contaminants
SE435581B (en) * 1982-08-16 1984-10-08 Celleco Ab PROCEDURE FOR DIVIDING A MIXTURE OF A RELATIVELY LOWER FIBER SUSPENSION (ACCEPT) AND LIGHT POLLUTION (REJECT)
SE451736B (en) * 1983-09-19 1987-10-26 Nils Anders Lennart Wikdahl WHEN WATERING A WATER SUSPENSION CONTAINING CELLULOSA FIBERS
JP5650037B2 (en) 2011-03-30 2015-01-07 株式会社タムロン Telephoto zoom lens

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0090928A2 (en) * 1982-04-05 1983-10-12 CLARK & VICARIO CORPORATION Multiple hydrocyclone apparatus
WO1986003143A1 (en) * 1984-11-28 1986-06-05 Noel Carroll Cyclone separator
DE3722440A1 (en) * 1986-07-10 1988-01-14 N Proizv Ob Krachmaloproduktam Multi-cyclone system

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5753083A (en) * 1995-06-27 1998-05-19 Voith Sulzer Papiermaschinen Gmbh Hydraulic support arrangement for a shoe press device
WO1998011297A1 (en) * 1996-09-16 1998-03-19 Alfa Laval Ab A method and a plant for treating of a contaminated pulp suspension
WO1998011296A1 (en) * 1996-09-16 1998-03-19 Alfa Laval Ab Method and plant for treating a contaminated pulp suspension
WO2003016617A1 (en) * 2001-08-15 2003-02-27 Metso Paper, Inc. Headbox of a paper machine or equivalent
RU2708110C1 (en) * 2019-04-09 2019-12-04 Николай Васильевич Байкин Fibrous materials sorting device

Also Published As

Publication number Publication date
EP0422314A1 (en) 1991-04-17
ES2023626T3 (en) 1994-07-01
DE68914666T2 (en) 1994-08-18
DE68914666D1 (en) 1994-05-19
NO178348C (en) 2001-03-05
ATE104382T1 (en) 1994-04-15
NO178348B (en) 1995-11-27
ES2023626A4 (en) 1992-02-01
BR9006945A (en) 1991-10-08
CA2042366A1 (en) 1991-04-11
EP0422314B1 (en) 1994-04-13
CA2042366C (en) 1995-07-04
DD296722A5 (en) 1991-12-12
DE422314T1 (en) 1991-07-25
NO912197D0 (en) 1991-06-07
NO912197L (en) 1991-06-07
JPH04502188A (en) 1992-04-16
JPH0781240B2 (en) 1995-08-30

Similar Documents

Publication Publication Date Title
US4704201A (en) Waste paper processing system
US4231526A (en) Process and apparatus for treating waste paper
NO178705B (en) Process for Removing Color Particles and / or Sticky Contaminants from Recycled Paper-Cellulose Pulp
EP0422314B1 (en) A method and device for the production of cellulose pulp of improved quality
FI82082B (en) FOERFARANDE OCH ANORDNING FOER BEHANDLING AV MASSA.
CN108137709A (en) The production method of cellulose nanometer fibril
JP2003516480A (en) Printing paper raw material, manufacturing method thereof and printing paper
EP1071844B1 (en) A process and apparatus for the production of cellulose pulps of improved quality
US6003683A (en) Forward or reverse hydrocyclone systems and methods
EP1592841B1 (en) Apparatus and method in the treatment of the stock passed to a headbox of a paper machine or equivalent
US5470432A (en) Method and arrangement for the treatment of a fiber suspension
FI102302B (en) Method and apparatus for producing cellulose pulp with improved quality properties
US7951263B2 (en) Method and apparatus for treating pulp
CA2228440A1 (en) Forward or reverse hydrocyclone systems and methods
US3237763A (en) Method and apparatus for concentrating fibrous suspensions
SE507387C2 (en) Process and plant for treating a contaminated pulp suspension
US3007519A (en) Cleaning systems for paper making machines
JPS60151394A (en) Concentration of fiber suspension in concentrator
FI116575B (en) Paper Machine Method and Arrangement
WO2004067838A1 (en) Method and device for handling filler-containing broke in a paper machine and a board machine
FI75197B (en) SAETT VID URVATTNING AV EN FIBERSUSPENSION I EN URVATTNINGSANORDNING.
SE431572B (en) Process for cleaning fibre suspensions, especially in the cellulose and paper industry, in a hydrocyclone installation

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): BR CA FI JP NO US

WWE Wipo information: entry into national phase

Ref document number: 2042366

Country of ref document: CA

WWE Wipo information: entry into national phase

Ref document number: 912765

Country of ref document: FI

WWG Wipo information: grant in national office

Ref document number: 912765

Country of ref document: FI