EP0055701B1 - Verfahren zum Regeln eines Druckbehälters zur Behandlung von Zellstoff - Google Patents

Verfahren zum Regeln eines Druckbehälters zur Behandlung von Zellstoff Download PDF

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Publication number
EP0055701B1
EP0055701B1 EP81890204A EP81890204A EP0055701B1 EP 0055701 B1 EP0055701 B1 EP 0055701B1 EP 81890204 A EP81890204 A EP 81890204A EP 81890204 A EP81890204 A EP 81890204A EP 0055701 B1 EP0055701 B1 EP 0055701B1
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EP
European Patent Office
Prior art keywords
pulp
vessel
flow
flow rate
treatment
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.)
Expired
Application number
EP81890204A
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English (en)
French (fr)
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EP0055701A1 (de
Inventor
Finn Jacobsen
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.)
Metso Fiber Karlstad AB
Original Assignee
Kamyr AB
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Application filed by Kamyr AB filed Critical Kamyr AB
Priority to AT81890204T priority Critical patent/ATE16614T1/de
Publication of EP0055701A1 publication Critical patent/EP0055701A1/de
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Publication of EP0055701B1 publication Critical patent/EP0055701B1/de
Expired legal-status Critical Current

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    • 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
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/02—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents

Definitions

  • the invention relates to a method of controlling a pressure-tight vessel for treating cellulosic pulp flowing in a substantially continuous stream, comprising feeding pulp into the vessel at a controlled flow rate, withdrawing treated pulp at a controlled flow rate, feeding treatment liquid into the vessel, and withdrawing treatment liquid at a controlled flow rate.
  • the conventional filtrate tanks also require adequate pump capacity and pressure head controls to both dilute the incoming stock and circulate the excess (surplus) liquor countercurrently back into the process.
  • Considerable pressure head on the pump or pumps is required since the pressure process is conventionally kept well above the static head of the filtrate tank which was exposed to the atmosphere.
  • the conventional diffusers needed extraction liquor flow control and separate wash liquor flow control to the preceding stage in multi-stage arrangements.
  • a known method of bleaching cellulosic pulp continuously fed through a bleaching plant comprising at least two chemical treatment stages (FR-A-1 468 440) the consistency and the flow rate of the pulp at a point of supply thereof to the bleaching plant are maintained constant at desired set values, and a desired change of consistency of the pulp at a point of transfer from a preceding stage to a subsequent stage is caused by adding or withdrawing liquid at such a rate as is required for maintaining the rate of flow of the pulp at said transfer point constant at a predetermined value.
  • a flow rate meter and a valve controlled by said flow rate meter there is no relation-back between said valves of different stages.
  • the invention as claimed is intended to remedy these drawbacks. It solves the problem of providing a method facilitating control of the absolute value of the consistency of the cellulosic pulp discharged from the plant in that the flow rate of the pulp entering the vessel and the flow rate of the treatment liquid leaving the vessel is controlled in response to the flow rate of the pulp leaving the vessel and consistency of the pulp leaving the vessel.
  • the advantages offered by the invention are mainly that variations in pulp characteristics, production rate and temperature will not affect pulp consistency since they will be governed purely through flow control using straightforward instrumentation regulators.
  • all flows in and out of the vessel are kept constant and continuous to eliminate the problems commonly associated with such vessels. Consequently, pressurized diffusers may now be easily incorporated in a pressurized system thereby eliminating the need for intermediate surge tanks, reducing pump power demand to a minimum, and totally eliminating the air entrainment and gas emission problems since the present invention no longer requires atmospheric discharge.
  • Level controllers will no longer be required and the number of flow controllers is almost halved since the extraction controller for one stage now concurrently serves as the wash liquor controller for the preceding stage.
  • the present invention covers a method for controlling the continuous flow of cellulosic material suspensions of medium consistency (8% to 15% BD) in pulp processing to achieve simpler and more efficient dewatering.
  • Additional cellulosic flow treatment may include feeding treatment liquid into the liquid inlet and may also include chemical admission and/or temperature control over the treatment (wash- displacement) liquid relative to the characteristics of the pulp withdrawn through the pulp outlet.
  • adapting the method to a multistage pressurized diffuser system comprises connecting the desired number of such diffusers in series using the pulp withdrawn from one diffuser as the pulp feed for the succeeding diffuser with optional intermediate temperature and chemical control of the treatment liquid relative to the pulp flow through the pulp outlet. Further, passing the pulp through an enlarged portion of the feed pipe or a vessel between the diffusers provides a desired retention time between liquid extractions.
  • the agitator in the outlet end of the first diffuser in series measures pulp concentration.
  • the exemplary diffuser 10 illustrated in Figure 1 comprises a conical housing 11 with top part 11' and bottom part 11" having a pulp inlet 12 and outlet 13, with a powered rotatable scraper 14 mounted in the bottom of housing 11 facilitating discharge of pulp from the housing 11 after treatment.
  • a withdrawn liquid outlet 17 extends from the top part of the housing 11.
  • a screen body 18 is mounted inside and substantially concentric with the housing 11, the body 18 having perforations or apertures formed therein to allow passage of liquid therethrough but prevent the passage of suspended solids therethrough.
  • the bearings 19 and 19' are provided between the body 18 and housing 11 to allow relative linear movement of screen 18 with respect to housing 11 in dimension "A".
  • the screen 18 is rigidly attached to one end thereof to a reciprocal shaft 23, which shaft 23 passes through a seal 24 at the top of the housing 11.
  • a conventional drive device 25 (such as shown in U.S. Patent 4,041,560) reciprocates the shaft 23 in dimension A. Normally, drive 25 will operate to move the screen 18 downwardly at about the same speed as the pulp flow from inlet 12 to outlet 13, and then move it upwardly much more quickly, and then restart the downward movement.
  • the speed and nature of operation of the drive 25 may be varied as desired to accomplish the objectives of the present invention, as may be the details, dimensions, and relative spacings, of the housing 11 and screen 18.
  • a treatment liquid inlet 26 is provided for treatment of suspension passing through the housing 11.
  • Treatment liquid introduced through inlet 26 is spread out by baffles 27 arranged circumferentially around a concentric liquid distribution body 15 fastened to the housing part 11" by three arms 15' of which one is hollow and in connection with the inlet 26.
  • exemplary apparatus utilizable in practicing the method of the invention includes pressurized diffuser 10, and associated inlet and outlet flow controls and the like.
  • the pulp flow (slurry) from a continuous digester, a storage tower or the like enters pipeline 28, flows through stock pump 29 (which alternatively may comprise a valve), and enters the top of the vertically aligned pressurized diffuser 10 and flows past movable screen 18 therein.
  • the pulp flow entering pressurized diffuser 10, possibly of varying consistency, is stabilized in consistency under its passage through the diffuser 10 by means of fine adjustment of the extraction flow 30 through outlet 17 relative to wash liquor flow 31 into inlets 26 of said pressurized diffuser 10.
  • the bottom discharging agitator 14 of pressurized diffuser 10 gives a very reliable output signal for consistency control to a consistency controller 32 and control ratio relay 33.
  • This signal adjusts the set point of control ratio relay 33 between the wash liquor flow control FIC 34 and the extraction liquor flow control FIC 35.
  • Control ratio relay 33 may have a limited range, for example, 0.9-1.3, to keep extraction flow deviations within the desired tolerances.
  • the discharge flow 36 from outlet 13 is measured by pulp discharge flow monitor 37 and a signal is transmitted to pre-set pulp flow controller FIC 38 which controls the stock pump 29 feeding the diffuser 10 [or controls a valve, depending on the pressure in the preceding vessel and the pressure demand for succeeding processes]. From pulp flow controller FIC 38, a proportional signal is transmitted to pulp flow ratio relay 39 which in turn controls the set point of the wash liquor controller FIC 34 which governs the wash liquid flow to the pressure diffuser 10.
  • Wash (or displacement) liquor flow controller FIC 34 receives signals from wash liquor sensing means 40 and pulp flow ratio relay 39 to send a composite signal to control ratio relay 33.
  • the composite signal through wash liquor controller FIC 34 governs the flow of wash liquor to the pressurized diffuser 10 through wash liquor control means 41.
  • the composite signal is set from wash liquor controller FIC 34 to control ratio relay 33.
  • a signal is then transmitted from control ratio relay 33 to extraction flow controller FIC 35.
  • the combination of the signals from extraction flow sensing means 42 and from the control ratio relay 33 through extraction flow controller FIC 35 governs the extraction flow control means 43.
  • simultaneous pulp flow and consistency control is achieved by regulating the extraction liquor flow relative to the wash liquor flow with reference to the pulp discharge flow, which in turn governs inlet pulp flow and wash liquor flow. That is, if the consistency of the incoming pulp stream tends to drop, the extraction flow will increase to maintain constant discharge consistency, while the pulp flow entering the diffuser will increase correspondingly so as to maintain a constant fiber flow discharging from the diffuser.
  • the flow control system operates generally according to the description of Figure 2, moreoverto optimize performance of pressurized diffuser 10, the speed of screen 18 may be automatically adjusted to match that of the average pulp stream speed through pressurized diffuser 10 by means of a pressure differential control PDIC 44 which regulates the drive 25 (e.g., regulates the flow of oil when drive 25 is a hydraulic cylinder) relative to the pressure differential between the top and bottom of diffuser 10, taken at points 45, 46.
  • the optimization process is independent of the flow and consistency control system described in Figure 2.
  • FIG 4 shows the flow and consistency control system as shown in Figure 2 and the pressure differential control PDIC 44 optimization method shown in Figure 3 with the addition of chemical admission controller FIC 47 and stock temperature controller TIC 48 which are connected to the wash liquor line 31 just prior to the wash liquor control 41.
  • Displacement or wash liquor enters pipeline 49 and chemical additions made at point 50 are controlled by chemical admission controller FIC 47 which receives the necessary data, for example, on pH or conductivity, from trans: mitter 51 which may be located directly in the discharging pulp stream 36.
  • the chemical admission controller combines the signal from transmitter 51 with one from chemical flow sensor means 52 to determine the amount of chemical admissions through chemical flow control 53 (which may be a valve or pump).
  • Passing wash (displacement) liquor through heat exchanger 54 permits the indirect heating or cooling of the pulp stream itself passing through the pressurized diffuser 10.
  • the temperature of the heat exchange medium is regulated through temperature controller TIC 48 and attendant flow control 55 wherein the temperature data transmitter 56 may be located in the discharging pulp stream 36. The location of the temperature data transmitter 56 allows automatic temperature control of the pulp stream entering succeeding treatment steps by controlling the temperature of the pulp stream discharging from the preceding diffuser.
  • a multi-stage pressure diffuser arrangement employing the flow control method can be understood with reference to Figure 5. While Figure 2 illustrates in detail the flow control system of a single diffuser, Figure 5 illustrates a multi-stage arrangement.
  • the wash liquid flow controller 34 of Section A becomes the extraction flow controller for diffuser 10' of Section B, and similarly the wash liquid flow controller 34' of Section B becomes the extraction flow controller for diffuser 10" of Section C.
  • the ratio relay 39 sends identical signals to the subsequent flow controllers 34', 34", so that they are automatically set at the same flow rate.
  • booster pumps 58, 58', 58" only have pressure heads sufficient to compensate for decreases in pressure through, for example, control valves 41, 41' and 41" and pipings.
  • booster pumps 58, 58', 58" can raise the wash (displacement) liquor pressure from diffuser 10' to that in the preceding diffuser 10. This additional pressure head need basically correspond to pulp line friction losses between the diffusers.
  • extraction flow 30 from the first pressurized diffuser 10 which governs the pulp flow consistency of the system should be free of surge effects.
  • extraction flow 30 from diffuser 10 should enter a surge or liquor tank 59.
  • Tank 59 the only one required in the flow control system, may be pressurized if the diffusers 10, 10', 10" are connected in the blow line from a pressurized vessel (e.g., continuous digester or oxygen reactor).
  • a vapor or gas cushion 60 acting on the gas relief flow 61 through valve 62 enables tank 59 to absorb surges.
  • Gas analyzers 63 may be incorporated in the gas relief line 61 if desired. This prevents surge flow variances from affecting succeeding process steps.
  • the other constant flow and consistency effects are obtained according to the steps described with Figure 2.
  • the discharging pulp stream 36" from the final diffuser 10" may flow directly to any final treatment or processing stage or into a storage tower.
  • a discharge pressure control PIC 64 governs the pressure of the discharging stream 36" relative to that of final pressure diffuser 10" by controlling valve 65. It is understood that the present invention is not limited to a three-stage system.
  • FIG. 6 A multiple stage arrangement employing the flow control method with intermediate chemical admission to the wash (displacement) liquor is illustrated in Figure 6.
  • the chemical, admission controller 47' operates in a similar manner to that described with Figure 4.
  • the indirect heating and cooling of the wash (displacement) liquor in the heat exchange 54, and associated components also operate in the same manner as in Figure 4.
  • Utilization of the optional hydraulically filled retention vessel 66 necessitates that the chemical admission controller FIC 47' combines the signals received from transmitter 52 and ratio relay 67 which in turn receives a signal proportional to the pulp flow in line 36. A change in the pulp flow will thus result in an immediate and proportional change in chemical admission flow.
  • the systems as described above are capable of practicing the method of the invention so that the flow rate of the pulp being withdrawn through the pulp outlet 36 by controlling the flow rate (by control of pump 29) of pulp fed into the first stage diffuser 10; and are capable of setting and controlling the consistency of the pulp being withdrawn through outlets 36, 36" by controlling the flow rate (via flow controller 35) of withdrawn liquid from outlet 17 of first stage diffuser 10 through conduit 30.
  • the nature of the pulp treatment and the qualities of the pulp withdrawn from each stage are controlled by adding desired chemicals to the treatment liquids introduced into inlets 26 through lines 31, 31', and controlling the temperature of the treatment liquid via temperature controllers 48 and associated heat exchangers 54.
  • the qualities of the withdrawn pulp in lines 36, 36" are sensed (by components 51 and 56), and control of the treatment liquid chemical addition and temperature is effected in response to such sensing.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
  • Immobilizing And Processing Of Enzymes And Microorganisms (AREA)
  • Medicines Containing Antibodies Or Antigens For Use As Internal Diagnostic Agents (AREA)
  • Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)
  • Processing Of Color Television Signals (AREA)
  • Investigating Or Analysing Biological Materials (AREA)
  • Materials For Medical Uses (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)

Claims (8)

1. Verfahren zum Regeln eines Druckbehälters zur Behandlung von Zellstoff, wobei die Pulpe in einer gleichförmigen Strömung geführt wird, mit einem Eintrag der Pulpe in den Behälter mit einer regelbaren Durchflußrate, mit einem Austrag der behandelten Pulpe mit einer regelbaren Durchflußrate, mit einem Eintrag einer Behandlungsflüssigkeit in den Behälter und mit einem Austrag der Behandlungsflüssigkeit mit einer regelbaren Durchflußrate, dadurch gekennzeichnet, daß die Durchflußrate der in den Behälter eingetragenen Pulpe und die Durchflußrate der Behandlungsflüssigkeit aus dem Behälter in Abhängigkeit von der Durchflußrate der Pulpe aus dem Behälter und der Konsistenz der aus dem Behälter ausgetragenen Pulpe geregelt wird.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Art der Behandlung der Pulpe und die Beschaffenheit der aus dem Behälter ausgetragenen Pulpe durch den Zusatz gewünschter Chemikalien zur Behandlungsflüssigkeit und durch Regelung der Temperatur der Behandlungsflüssigkeit geregelt wird, daß die Beschaffenheit der aus dem Behälter ausgetragenen Pulpe gemessen wird und daß der Beimengung von chemischen Zusätzen und die Behandlungstemperatur in Abhängigkeit dieser Meßresultate geregelt wird.
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, daß die aus dem Behälter ausgetragene Pulpe in einen zweiten, daran anschließenden Behandlungsapparat eingebracht wird.
4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, daß die aus dem zweiten Behandlungsapparat ausgetragene Pulpe in einen dritten, daran anschließenden Apparat eingebracht wird, wobei die aus dem Behälter ausgetragene Behandlungsflüssigkeit als Behandlungsflüssigkeit im vorangehenden Apparat Verwendung findet.
5. Verfahren nach Anspruch 3 oder 4, dadurch gekennzeichnet, daß die aus dem Behälter ausgetragene Pulpe aufgestaut wird, bevor die Pulpe in den daran anschließenden Apparat eingebracht wird.
6. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die charakteristischen Eigenschaften der aus dem Behälter ausgetragenen Pulpe gemessen werden, daß die Temperatur der zu behandelnden Pulpe durch Beheizung oder Abkühlung der Behandlungsflüssigkeit indirekt eingestellt wird, daß die charakteristischen chemischen Eigenschaften der Pulpe durch die Beimengung chemischer Zusätze in die Behandlungsflüssigkeit geregelt werden, und daß die Beimengung chemischer Zusätze und die Temperatur der Behandlungsflüssigkeit in Abhängigkeit der Messungen der charakteristischen Eigenschaften der Pulpe geregelt werden.
7. Verfahren nach Anspruch 1 oder 6, dadurch gekennzeichnet, daß die Durchflußrate und die Konsistenz der aus dem Behälter ausgetragenen Pulpe gemessen werden.
8. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß im Druckbehälter nahe der Eintrags- öffnung für die Pulpe ein bewegliches Sieb angeordnet ist, und daß die Siebgeschwindigkeit in Richtung der Strömung der Pulpe mit der durchschnittlichen Geschwindigkeit der in der Strömung zu behandelnden Pulpe übereinstimmt.
EP81890204A 1980-12-31 1981-12-18 Verfahren zum Regeln eines Druckbehälters zur Behandlung von Zellstoff Expired EP0055701B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81890204T ATE16614T1 (de) 1980-12-31 1981-12-18 Verfahren zum regeln eines druckbehaelters zur behandlung von zellstoff.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US22181280A 1980-12-31 1980-12-31
US221812 1980-12-31

Publications (2)

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EP0055701A1 EP0055701A1 (de) 1982-07-07
EP0055701B1 true EP0055701B1 (de) 1985-11-21

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EP81890204A Expired EP0055701B1 (de) 1980-12-31 1981-12-18 Verfahren zum Regeln eines Druckbehälters zur Behandlung von Zellstoff

Country Status (8)

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EP (1) EP0055701B1 (de)
JP (1) JPS57133292A (de)
AT (1) ATE16614T1 (de)
BR (1) BR8108558A (de)
CA (1) CA1173603A (de)
DE (1) DE3173030D1 (de)
FI (1) FI69139C (de)
NO (1) NO157626C (de)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4793161A (en) * 1987-11-27 1988-12-27 Kamyr Ab Effective diffuser/thickener screen backflushing
US4908896A (en) * 1987-11-27 1990-03-20 Kamyr Ab Backflushing pressure diffuser screens
US5066362A (en) * 1987-12-01 1991-11-19 Kamyr, Inc. Extended delignification in pressure diffusers
US5021127A (en) * 1987-12-01 1991-06-04 Kamyr, Inc. Extended delignification in pressure diffusers
SE462435B (sv) * 1988-11-11 1990-06-25 Kamyr Ab Saett att stabilisera tryck- och floedesfoerhaallandena i en silapparat och silapparat haerfoer
US4975148A (en) * 1988-12-06 1990-12-04 Ahlstromforetagen Svenska Ab Cold blow system for batch production of pulp
FI82082C (fi) * 1989-03-29 1991-12-10 Ahlstroem Oy Foerfarande och anordning foer behandling av massa.
US5538632A (en) * 1993-10-28 1996-07-23 Beloit Technologies, Inc. Multiple filter dynamic washer
JPWO2015080190A1 (ja) * 2013-11-29 2017-03-16 三菱化学株式会社 スラリーの洗浄装置及び洗浄システム
FI130499B (en) * 2021-03-25 2023-10-10 Metsae Fibre Oy Method and device for treating mixtures of liquids and solids

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE312269B (de) * 1964-12-17 1969-07-07 T Aremaa
FR1468440A (fr) * 1965-02-17 1967-02-03 Kamyr Ab Procédé pour agir sur la consistance de pulpe cellulosique dans des installations de blanchiment
US3807202A (en) * 1969-09-30 1974-04-30 K Gunkel Continuous washing apparatus for pulp stock and the like
SE394821B (sv) * 1975-04-15 1977-07-11 Kamyr Ab Sett och anordning for avvattning av suspensioner i rorelse
GB1566099A (en) * 1976-11-11 1980-04-30 Largo Lintec Ltd Pulping cellulosic material
US4212239A (en) * 1979-02-15 1980-07-15 Hobart Corporation Method and apparatus for removing moisture from wet pulp

Also Published As

Publication number Publication date
EP0055701A1 (de) 1982-07-07
DE3173030D1 (en) 1986-01-02
FI814173L (fi) 1982-07-01
NO157626C (no) 1988-04-20
FI69139C (fi) 1985-12-10
BR8108558A (pt) 1982-10-19
CA1173603A (en) 1984-09-04
ATE16614T1 (de) 1985-12-15
JPS57133292A (en) 1982-08-17
FI69139B (fi) 1985-08-30
NO157626B (no) 1988-01-11
NO814440L (no) 1982-07-01

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