US3338525A - Method of cooling pulp suspensions in grinding and refining operations - Google Patents

Method of cooling pulp suspensions in grinding and refining operations Download PDF

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Publication number
US3338525A
US3338525A US413207A US41320764A US3338525A US 3338525 A US3338525 A US 3338525A US 413207 A US413207 A US 413207A US 41320764 A US41320764 A US 41320764A US 3338525 A US3338525 A US 3338525A
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United States
Prior art keywords
grinding
pulp
temperature
conduit
cooling
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Expired - Lifetime
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US413207A
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English (en)
Inventor
Asplund Arne Johan Arthur
Karl N Cederquist
Reinhall Rolf Bertil
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Valmet AB
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Defibrator AB
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Publication date
Application filed by Defibrator AB filed Critical Defibrator AB
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D1/00—Methods of beating or refining; Beaters of the Hollander type
    • D21D1/20—Methods of refining
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
    • D21B1/00—Fibrous raw materials or their mechanical treatment
    • D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
    • D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D1/00—Methods of beating or refining; Beaters of the Hollander type
    • D21D1/02—Methods of beating; Beaters of the Hollander type
    • D21D1/12—Beaters with means for continuous pulp discharge
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G9/00—Other accessories for paper-making machines

Definitions

  • This invention relates to a method of cooling pulp suspensions in grinding and refining operations.
  • pulp types contemplated here comprise all kinds of sernichemical, chemomechanical and mechanical pulp made of wood chips which are produced with high yield ranging from 75 to 95 percent and contain a substantial quantity of lignin and'hemicellulose.
  • One main object of the invention is to overcome the difficulties set forth in a novel way by providing a method which renders poscomprises between 35 and 45 material, is in a plastic state at temperature about or immediately above 100 C. and that at a temperature of C. already part of the 'intercellular substance has begun to be converted into an amorphous plastic mass. Itis probable that this plastic state drastically obstructs the fibrillation and prolongs the grinding time required for attaining a desired or predetermined freeness. It has also been established that the temperature in grinding and refining processes must not exceed 100 C. and suitably not surpass C. The best results have been attained with temperatures not exceeding 60 to 70 C.
  • FIG. 1 is a more or less diagrammatical'lateral eleva; tion of a plant constructed according to the invention.
  • FIG. 2 is a similar lateral elevation of a plant according to a modified embodiment of the invention.
  • FIG. 3 is a sectional view line III-III of FIG. 2.
  • the embodiment according to FIG. 1 illustrates a re fining operation carried out in three stepswith a coolingby applying negative pressure to the two last steps thereof.
  • the refining is intended to be effected in a disc refiner negative pressure there areno difficulties in pumping pulpon a larger scale following with a chemo-mechanical spruce stock manufactured in the manner described hereinbefore and with the same yield.
  • the freeness of the defibrated pulp is about 720 CSF and the pulp shall be ground and refined to a freeness value of 150 CSF. In the grinding and refining to a freeness of 150 CSF totally 700 kwh. are consumed per one ton of stock which value when divided to the three steps gives about 230 kWh. per one ton of stock in each step.
  • reference numeral denotes a centricleaner into which the digested pulp ground in a defibrator (not shown) is introduced through a conduit 12.
  • the stock may be withdrawn through a sluice from the defibrator in which superatmospheric pressure exists, accompanying steam and uncondensable gases escaping from the centricleaner 10 through a pipe 14.
  • the pulp is assumed to have a bone-dry content of about 17 percent and a temperature of 100 C. upon having left the defibrator.
  • Cooling water having a temperature of 20 C. is at the sametime supplied to the centricleaner 10 through a pipe 16 in such quantity that a pulp concentration of about 10 percent is obtained in the bin 18 disposed under the centricleaner.
  • Disposed in the bin 18 may be an impeller member 22 driven by an electric motor 20. If it is necessary entirelyor partly to remove the digestion chemicals prior to the refining steps such removal is most suitably efliected by washing the stock in bins, on sieves or by means of presses located between the centricleaner 10 and the bin 18.
  • the pulp suspension is now conducted through a conduit 24 which may house a pump 26, to a first refiner 28 driven by an electric motor 30.
  • a grinding is effected at a temperature which must not surpass 60 C.
  • the temperature rise will thus be 20 C.
  • the refiners may prevail a pressure of 1-3 kilograms per square centimeter for example.
  • the refiners may be of the type shown and described in the US. patent specification No. 2,891,733.
  • a temperature of 60 C. exists in the discharge conduit 32 from the refiner 28.
  • a cooling is now effected according to the invention in an evaporator 34, in which a negative pressure is maintained which in the embodiment in consideration is an absolute pressure of 55 mm. Hg corresponding to a boiling point of the water at 40 C.
  • a throttling or pressure reducing valve 36 is provided in the conduit 36 and further the conduit 32 may be given a height assisting in keeping a higher pressure in the refiner 28 than in the evaporator 34.
  • the suspension is introduced tangentially into said evaporator.
  • the pulp suspension cooled in the evaporator 34 is fed through a conduit 52 and a pump 53 into a second refiner 54 driven by an electric motor 56.
  • a renewed grinding is effected under rise of temperature so that the pulp suspension entering the discharge conduit 58 again has been heated to 60 C.
  • a conduit 60 provided with a throttle valve 62 part of the ground pulp may be returned to the evaporator 34 for repeated cooling therein and a subsequent grinding treatment in the refiner 54.
  • the conduit 58 is through a throttle valve 64 connected to a second evaporator 66 in which a negative pressure is kept in the same manner as in the evaporator 34 to cause the pulp suspension to be cooled to 40 C. by evaporation of water.
  • the developed vapors escape through a conduit 68 to a condenser 70 which through a conduit 72 is in connection with the vacuum pump 46 and which through the pipe 42 is supplied with cooling water.
  • the condensate is discharged from the condenser 70 through the conduit 74 in which a liquid column is built up which is capable of surmounting the negative pressure in the condenser.
  • the conduit 74 is extended downwardly below the liquid level in an open vessel 76 in the same manner as the conduit 48.
  • conduit 78 which may house a pump 79 extends to a third refiner 80 driven by an electric motor 82.
  • this refiner still another grinding of the pulp is effected which then leaves through a conduit 84 controlled by a valve 86 for a following treating step which does not form part of the present invention and therefor not described here.
  • the temperature of the leaving pulp is this time also 60 C.
  • Part of the fiber pulp may be recycled through a conduit 88 provided with a throttle valve 89 to the evaporator 66.
  • the refining is conducted with recycling of cooled refined pulp it is possible to operate with somewhat higher pressure on/ and corresponding higher temperature of, the entering pulp suspension w'thout the temperature during the grinding process surpassing the allowable upper limit.
  • the quantity of pulp passed through each refiner per time unit becomes greater and the suspension becomes capable of taking up more heat per each grade of temperature rise than in the case where no recycling is applied.
  • the refiner is constructed in a specific manner, it is also possible directly to produce negative pressure in their interior and continuously to remove the produced steam at the same rate as the forming thereof and in this manner to conduct the grinding operation at a constant temperature.
  • FIGS. 2 and 3 illustrate diagrammatically a constructive embodiment of this modification of the method.
  • a refiner 90 is provided with a horizontal stationary cylinder 91 within which a grinding member 92 is rotatably mounted.
  • This member is formed with a central, four-edged boxlike beam which at its ends has axle journals 94, 96.
  • the axle journal 94 is connected to a driving motor 98.
  • the grinding member 92 has further four wings which during rotation of the member knead the material against the interior wall of the cylinder 91 which wall may be grooved to increase the friction.
  • the beam-formed portion of the grinding member has perforations 102 and the axle journal 96 is provided with a central bore and by means of a box'device 104 and a stationary pipe conduit 106 connected to an injection condenser 108. This latter is fed with cooling water through a conduit 1110 and kept at negative pressure by means of a vacuum pump 112.
  • a negative pressure corresponding to a boiling point of the water of 55 C. is applied to the cylinder 91.
  • a relatively concentrated pulp suspension the concentration of which may amount to between 10 and 20 percent, is fed into the cylinder from a container 114 through a conduit 116 in which is disposed a sluice or throttle valve 118.
  • the ground pulp is discharged through a conduit 120.
  • the pulp during its passage through the cylinder is ground by the grinding member 92, the developed heat being transformed to steam which is continuously withdrawn 5 through the bored journal 96 to the condenser 108. The heat escapes in vapor enthalpy and a constant temperature will prevail in the suspension.
  • the ground pulp is conveyed through the conduit 120 to a container 122 and Withdrawn for further treatment or working through a conduit 124 which is provided with a pump 126 and a valve 128. From the condenser 108 a conduit 130 extends to the container 122 for maintaining the desired negative pressure in said container. Through a conduit 132 housing a valve 134 pulp suspension may 10 be recycled by the pump 126 until the desired degree of .refining has been reached.
  • a conduit 136 extends from the condenser 108 down into a drain container 138, said conduit having a length surpassing the length corresponding to the negative pressure in the condenser.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
US413207A 1964-03-10 1964-11-23 Method of cooling pulp suspensions in grinding and refining operations Expired - Lifetime US3338525A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE2986/64A SE308983B (es) 1964-03-10 1964-03-10

Publications (1)

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US3338525A true US3338525A (en) 1967-08-29

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US413207A Expired - Lifetime US3338525A (en) 1964-03-10 1964-11-23 Method of cooling pulp suspensions in grinding and refining operations

Country Status (10)

Country Link
US (1) US3338525A (es)
AT (1) AT273651B (es)
BE (1) BE660872A (es)
CH (1) CH425443A (es)
DE (1) DE1461013A1 (es)
FI (1) FI44751C (es)
FR (1) FR1439080A (es)
NL (1) NL6503032A (es)
NO (1) NO125540B (es)
SE (1) SE308983B (es)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1912940A1 (de) * 1968-04-02 1970-02-26 Defibrator Aktiebolaget Verfahren zum Herstellen von mechanischem Faserstoff
US5219563A (en) * 1988-05-11 1993-06-15 Glaxo Group Limited Drug adsorbates
US6165317A (en) * 1995-06-12 2000-12-26 Andritz Sprout-Bauer, Inc. Control of refined pulp quality by adjusting high temperature pre-heat residence time
US20010050151A1 (en) * 1997-08-08 2001-12-13 Marc J. Sabourin Method of pretreating lignocellulose fiber-containing material for the pulp making process
WO2013072558A1 (en) * 2011-11-14 2013-05-23 Upm-Kymmene Corporation A disc refiner and a method for its use

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004014392B4 (de) * 2004-03-24 2007-04-12 Voith Patent Gmbh Verfahren zum Reinigen einer störstoffhaltigen Faserstoffsuspension für die Papiererzeugung

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US962118A (en) * 1908-09-14 1910-06-21 William H Bradley Drying apparatus.
GB519758A (en) * 1938-10-14 1940-04-04 George William Riley Improvements in or relating to apparatus for the treatment of grain and like granular materials
US2689688A (en) * 1949-11-04 1954-09-21 Lillian Maude Watts Low-pressure method and apparatus for pneumatic elevating
US2841339A (en) * 1954-03-25 1958-07-01 Dale T Gilmore Dehydrating and pulverizing machine

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US962118A (en) * 1908-09-14 1910-06-21 William H Bradley Drying apparatus.
GB519758A (en) * 1938-10-14 1940-04-04 George William Riley Improvements in or relating to apparatus for the treatment of grain and like granular materials
US2689688A (en) * 1949-11-04 1954-09-21 Lillian Maude Watts Low-pressure method and apparatus for pneumatic elevating
US2841339A (en) * 1954-03-25 1958-07-01 Dale T Gilmore Dehydrating and pulverizing machine

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1912940A1 (de) * 1968-04-02 1970-02-26 Defibrator Aktiebolaget Verfahren zum Herstellen von mechanischem Faserstoff
US5219563A (en) * 1988-05-11 1993-06-15 Glaxo Group Limited Drug adsorbates
US6165317A (en) * 1995-06-12 2000-12-26 Andritz Sprout-Bauer, Inc. Control of refined pulp quality by adjusting high temperature pre-heat residence time
US20010050151A1 (en) * 1997-08-08 2001-12-13 Marc J. Sabourin Method of pretreating lignocellulose fiber-containing material for the pulp making process
US6899791B2 (en) 1997-08-08 2005-05-31 Andritz Inc. Method of pretreating lignocellulose fiber-containing material in a pulp refining process
WO2013072558A1 (en) * 2011-11-14 2013-05-23 Upm-Kymmene Corporation A disc refiner and a method for its use

Also Published As

Publication number Publication date
FR1439080A (fr) 1966-05-20
BE660872A (es) 1965-09-10
NL6503032A (es) 1965-09-13
CH425443A (de) 1966-11-30
SE308983B (es) 1969-03-03
FI44751C (fi) 1971-12-10
AT273651B (de) 1969-08-25
NO125540B (es) 1972-09-25
FI44751B (es) 1971-08-31
DE1461013A1 (de) 1969-03-13

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