US3200032A - Continuous process for digesting cellulosic material - Google Patents

Continuous process for digesting cellulosic material Download PDF

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Publication number
US3200032A
US3200032A US245202A US24520262A US3200032A US 3200032 A US3200032 A US 3200032A US 245202 A US245202 A US 245202A US 24520262 A US24520262 A US 24520262A US 3200032 A US3200032 A US 3200032A
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United States
Prior art keywords
digesting
digester
liquor
fibrous material
cellulosic fibrous
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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 - Lifetime
Application number
US245202A
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English (en)
Inventor
Johan C F C Richter
Ole J Richter
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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Publication date
Priority claimed from JP4693661A external-priority patent/JPS498802B1/ja
Application filed by Kamyr AB filed Critical Kamyr AB
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Publication of US3200032A publication Critical patent/US3200032A/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/22—Other features of pulping processes
    • D21C3/26—Multistage processes

Definitions

  • the present invention relates to a continuous two-stage process for digesting cellulose and appartus adapted for carrying out this process.
  • the principal object of the invention is to provide a new and highly advantageous process and apparatus for the two-stage continuous digestion of cellulosic fiber material.
  • a more speciiic object of the invention is the provision of a two-stage cellulosic disgesting process and apparatus which are more economical and effective than prior proccdures and devices.
  • Other objects will also be hereinafter apparent.
  • the process of the invention involves charging cellulosic fiber material into one end of an elongated disgester, subjecting this material to a digesting cool: in two successive stages where the digesting liquor in the first stage flows concurrently with the tiber materiais and the liquor in the second stage flows countercurrently, discharging the thus digested material from the opposite end of the digester, washing the digested material subsequent to the second digesting cooi; but before discharge from the digester, and filtering od the spent digesting liquors from the digester in a Zone intermediate the inst and second digesting stages.
  • the apparatus contemplated herein comprises an elongated digester having a material inlet end and a material discharge end, means for continuously charging iiber material into the inlet end of the digester, means for continuously discharging digested fiber material from the discharge end of the digester, two successive digesting .zones positioned between the inlet and discharge ends of the digester, means for passing digesting liquor concurrently with the material through the first digesting zone, means for passing digesting liquor couutercurrently to the material through the second digesting zone, and sieve means intermediate the two digesting zones for straining ott spent digesting liquors from the digester.
  • the success of the invention is due to the combination of several unique features including concurrent flow between the digesting liquor and cellulosic iiber material in the first stage, countercurrent flow between the liquor and iiber material in the second stage and straining oit spent digesting liquor from the iber material in an intermediate or bordering zone between the digesting stages.
  • rthe straining operation may be performed through separate sieves, one for each digesting liquor, located relatively close to each other, or at comparatively small mutual distances.
  • Washing of the digested fiber material is preferably performed by passing a washing liquid comprising water, or tiltrate with digesting liquor residues, in countercurrent flow through the fiber material, after the second digesting stage but before discharge of the material from the digester.
  • the wash liquid is desirably passed into the digester, at or near the discharge end thereof, through a washing area to the second digestlidddfiz Patented Aug. 10, 1965 ing stage, where it is at least partly mixed with the digesting liquor of the second stage.
  • the resulting mixture of digesting liquor and washing liquid is then passed through the second digesting stage in countercurrent ow with the liber material.
  • the elongated digester of the invention is provided with appropriate sieve means, specifically, at least one, and generally, two sieve girdles, which are adapted to strain oit spent digesting liquors from the iiber material and are arranged along the wall of the digester at about Mi to 1/2 the length thereof, measured from the material inlet end.
  • the digester is also provided with conduit means at opposite sides of the sieve means for supplying two diterent digesting liquors so that the digesting liquors will pass through the ber material in opposite directions, i.e., first in concurrent ilow and then countercurrently, with respect to the fiber materal.
  • the spent liquors are then discharged through the sieve girdles in the intermediate zone between the two digesting stages.
  • the numeral 11 designates an upright cylindrical digester of essentially uniform crosssectional area, and a length equal to about ten times the diameter.
  • the digester is provided with appropriate charging or inlet means 13 of a type well known in the art, for example, as shown in United States Patent No. 2,459,180, utilizing a screw conveyor in the charging device, which is shown in more detail in Patent No. 2,459,180.
  • a comminuted cellulosic material, such as wood chips, is charged by the means 13 into the digester continuously or in the form of discrete successive batches.
  • the thus charged material moves aS a compact column vertically downward through the digester and is discharged at its lower end into a discharge conduit, generally indicated by the numeral 15, by means of a suitable discharging device, such as that shown in United States Patent No. 2,938,824.
  • the discharging device indicated generally as the pulp outlet 59, utilizes a screw conveyor which is shown in more detail in Patent No. 2,938,824.
  • the introduction and direction of feed of the charge material is indicated by the double arrows 17.
  • the fiber material is subjected to various treatment areas which are indicated as the separate Zones a, b, c and d, respectively.
  • the digesting liquor of the first digesting stage preferably consists of sulphate lye, c g., sodium or calcium sulphate lye.
  • the digesting liquor in zone a tiows in the same direction as the fiber material.
  • digesting liquor is sucked out through sieve girdle 23 by means of pump 2S, re-circulated in outer conduit 26 and through heating device 27, e.g., a heat exchanger, and then re-introduced through return tube 29, the latter terminating on the axis of the digester and discharging at approximately the level of, or somewhat above the level of, the sieve girdle 23.
  • the liquor circulating in said loop is heated by steam supplied as shown at fili to heat exchanger 27 to the desired temperature (eg, i0() to l75 C).
  • the fiow of liquor in the described circulation loop may be to 10 times as large as the flow of liquor in the longitudinal direction of the digester.
  • the heated liquor spreads from the orifice of the tube 29 radially outwards and heats the charge material to the desired digesting temperature.
  • heating may also take place by directly injecting steam into the outer circulation conduit or loop 26 or directly into ⁇ the digester.
  • the first stage digestion takes place in zone b, so that when the fiber material reaches the level of the second 'sieve girdle 33, digestion with the lye liquor is completed,
  • the lye liquor is strained olf through sieve girdle 33, and a part thereof is pumped by means of pump 35 back into circulation loop 25, and
  • the lye liquor in zone b still fiows in the same direction as the fiber material and by recirculation of the lye liquor, the liquor will move at a speed higher than the speed of the fiber charge material.
  • the lye liquor exerts a downwardly directed pressure kupon the material, which pressure, together with the gravity acting thereupon, aids in feeding the material coltotal length of the digester, and preferably at a point about 1/3 of the length thereof.
  • Sieve girdle 41 serves to strain off from the fiber material the spent digesting liquor employed in the second digesting stage c which digesting liquor flows upwardly in countercurrent relation to the direction of the fiber material in this stage, as indicated by the arrows 43. Between the two opposing liquor currents 39 and 46, there is formed a transition zone where the liquid is substantially stagnant or immobile.
  • Digesting liquor for the second stage is supplied through conduit 53 to pump 5l and then into digestion column lf by means of heat exchanger t7 and outlet orifice 4&9 at sieve girdle 45.
  • the second digesting zone c extends from sieve girdle 41 to the fourth sieve girdle 45, the latter being situated at a distance from the discharge end of the digester corresponding approximately to 1/s of the length of the digester.
  • Sieve girdle i5 is connected into a circulation loop 48 including heating device 47 and return tube 49, located centrally in the digester and having an outlet orifice located at the level of the sieve girdle d5, or somewhat higher. Part of the second digestion liquor is recovered at sieve girdle 45 and re-circulated through conduit 48 for reheating as in the case of the first digesting stage.
  • washing liquid may consist of pure water, or of filtrate taken from a subsequent wash filter and containing digesting liquor residues.
  • the washing liquid is supplied through spray nozzles S7 distributed around the periphery of the digester near pulp outlet 59.
  • a part of the wash liquid which also has a cooling effect, accompanies the pulp out through outlet 59.
  • Another part of the wash liquor is forced upwards through the material column and countercurrent thereto, as indicated by the arrows of, thereby displacing the digesting liquor from the réelle of tube 49, and forcing the same to move upwardly in countercurrent flow with respect to the fiber material, see arrows 43.
  • the second stage digesting liquor which is substantially spent, encounters the downwardly directed fluid current (see arrows 39) and is forced thereby to escape through sieve girdle 41.
  • the wash liquor fraction and second stage liquor fraction are passed to a container 63, cg., in the shape of a cyclone, which is maintained at a pressure considerably lower than the digesting pressure.
  • Liberated steam and gas are discharged from container 63 through conduit 65 in order to recover the heat content thereof, and spent liquor is discharged through conduit 67 to a chemical recovery plant.
  • the SO2 is let off through conduit 65 for return tothe digester.
  • the present invention is not limited to the digesting chemicals used herein but can be applied equally well with other digesting chemicals and processes which are susceptible and amenable to two-stage continuous operations in a single digester or vessel. To permit such use of the present invention, it is only necessary that the same pressure be used in the two treating stages, whereas the temperatures can be varied since it is Apossible for the temperature of the first stage herein to be considerably higher or lower than that of the second stage.
  • the present invention provides for the separation of spent lyes from distinct stages to permit recovery of their separate chemical contents. If recovery is not essential, or if the two types of spent lyes can be recovered simultaneously after mixing them, the conduits from sieves 33 and 41 can be connected together by means of conduit 69, whereby the recovery of both heat and chemical is greatly simplified.
  • a continuous process for digesting cellulosic iibrous material including the step of continuously charging cellulosic fibrous material into one end of an elongated digester; impregnating the cellulosic fibrous material with digesting liquor adjacent said one end ⁇ of the digester; digesting the impregnated material by treating the material with heated digesting liquor while passing it through the central portion of the digester; washing the material adjacent the other end of the digester; and discharging the digested material from said other end of the digester; the improvement which comprises conducting the digesting step in two stages by digesting the cellulosic fibrous material in a first digesting Zone in the central portion of the digester with heated digesting liquor owing through the first digesting zone concurrently with the cellulosic fibrous material; digesting the cellulosic fibrous material in a second digesting zone in the central portion of the digester with ⁇ a different digesting liquor flowing through the second digesting zone countercurrently with the cellulosic fibrous material;

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US245202A 1961-12-23 1962-12-17 Continuous process for digesting cellulosic material Expired - Lifetime US3200032A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP4693661A JPS498802B1 (enrdf_load_stackoverflow) 1961-12-23 1961-12-23
SE644562 1962-06-08

Publications (1)

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US3200032A true US3200032A (en) 1965-08-10

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US (1) US3200032A (enrdf_load_stackoverflow)
DE (1) DE1517143A1 (enrdf_load_stackoverflow)
FI (1) FI40678B (enrdf_load_stackoverflow)
NO (1) NO118248B (enrdf_load_stackoverflow)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303088A (en) * 1963-04-19 1967-02-07 Lummus Co Continuous liquid-phase rapid pulping
US3362868A (en) * 1963-01-11 1968-01-09 Kamyr Ab Method and apparatus for oxidizing spent digestion liquors
US3380883A (en) * 1963-09-27 1968-04-30 Kamyr Ab Method and apparatus for performing prehydrolysis in a continuous counterflow digester
US3413189A (en) * 1964-01-29 1968-11-26 Kamyr Ab Method of performing hydrolysis and alkalic digestion of cellulosic fiber material with prevention of lignin precipitation
US3425898A (en) * 1963-12-13 1969-02-04 Kamyr Ab Two stage chemical digestion within a single vessel with wash between stages
US3427218A (en) * 1964-07-10 1969-02-11 Kamyr Ab Method of performing counter-current continuous cellulose digestion
US3441475A (en) * 1965-07-09 1969-04-29 Domtar Ltd Continuous pulping apparatus
US3445328A (en) * 1964-01-25 1969-05-20 Kamyr Ab Method for continuous cellulose digestion utilizing two temperature zones
US3652384A (en) * 1966-06-24 1972-03-28 Ass Pulp & Paper Mills Countercurrent pulping of cellulosic materials including regulation of active chemical therein
US4002528A (en) * 1972-02-18 1977-01-11 Kamyr, Inc. Apparatus for processing pulp
US4061193A (en) * 1975-09-15 1977-12-06 Kamyr, Inc. Method and apparatus for digesting cellulose material without screening digesting liquid withdrawn through the digester top
US4071399A (en) * 1976-09-01 1978-01-31 Kamyr, Inc. Apparatus and method for the displacement impregnation of cellulosic chips material
US4941944A (en) * 1984-07-13 1990-07-17 Pierre A. Tonachel Method for continuous countercurrent ogranosolv saccharification of comminuted lignocellulosic materials
US5547012A (en) * 1993-05-04 1996-08-20 Kamyr, Inc. Dissolved solids control in pulp production
AU704580B2 (en) * 1993-05-04 1999-04-29 Kamyr Inc. Dissolved solids control in pulp protection
US5985096A (en) * 1997-09-23 1999-11-16 Ahlstrom Machinery Inc. Vertical pulping digester having substantially constant diameter
US20020129911A1 (en) * 2000-10-16 2002-09-19 Marcoccia Bruno S. Process and configuration for providing external upflow/internal downflow in a continuous digester
RU2486302C2 (ru) * 2008-03-20 2013-06-27 Метсо Пейпер Свиден Актиеболаг Система подачи, включающая насосы в параллельной компоновке, для варочного котла непрерывного действия
RU2490385C2 (ru) * 2008-03-20 2013-08-20 Метсо Пейпер Свиден Актиеболаг Система подачи, содержащая параллельно установленные насосы, для варочного котла непрерывного действия
US11162218B1 (en) 2020-09-30 2021-11-02 Robert Clayton Biomass pulp digester

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3212767A1 (de) * 1982-04-06 1983-10-06 Nicolaus Md Verwaltungsges Verfahren und reaktor zum kontinuierlichen aufschliessen von pflanzenfasermaterial

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2695232A (en) * 1950-07-08 1954-11-23 Kamyr Ab Apparatus for heating and controlling the temperature of a continuously operating cellulose digester
US2920697A (en) * 1953-03-28 1960-01-12 Braunschweigische Maschb Ansta Apparatus for the production of cellulose
US3035963A (en) * 1958-02-19 1962-05-22 Lummus Co Process for the continuous digestion of cellulosic materials
US3097987A (en) * 1960-02-08 1963-07-16 Ass Pulp & Paper Mills Continuous pulping process

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2695232A (en) * 1950-07-08 1954-11-23 Kamyr Ab Apparatus for heating and controlling the temperature of a continuously operating cellulose digester
US2920697A (en) * 1953-03-28 1960-01-12 Braunschweigische Maschb Ansta Apparatus for the production of cellulose
US3035963A (en) * 1958-02-19 1962-05-22 Lummus Co Process for the continuous digestion of cellulosic materials
US3097987A (en) * 1960-02-08 1963-07-16 Ass Pulp & Paper Mills Continuous pulping process

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3362868A (en) * 1963-01-11 1968-01-09 Kamyr Ab Method and apparatus for oxidizing spent digestion liquors
US3303088A (en) * 1963-04-19 1967-02-07 Lummus Co Continuous liquid-phase rapid pulping
US3380883A (en) * 1963-09-27 1968-04-30 Kamyr Ab Method and apparatus for performing prehydrolysis in a continuous counterflow digester
US3425898A (en) * 1963-12-13 1969-02-04 Kamyr Ab Two stage chemical digestion within a single vessel with wash between stages
US3445328A (en) * 1964-01-25 1969-05-20 Kamyr Ab Method for continuous cellulose digestion utilizing two temperature zones
US3413189A (en) * 1964-01-29 1968-11-26 Kamyr Ab Method of performing hydrolysis and alkalic digestion of cellulosic fiber material with prevention of lignin precipitation
US3427218A (en) * 1964-07-10 1969-02-11 Kamyr Ab Method of performing counter-current continuous cellulose digestion
US3441475A (en) * 1965-07-09 1969-04-29 Domtar Ltd Continuous pulping apparatus
US3652384A (en) * 1966-06-24 1972-03-28 Ass Pulp & Paper Mills Countercurrent pulping of cellulosic materials including regulation of active chemical therein
US4002528A (en) * 1972-02-18 1977-01-11 Kamyr, Inc. Apparatus for processing pulp
US4061193A (en) * 1975-09-15 1977-12-06 Kamyr, Inc. Method and apparatus for digesting cellulose material without screening digesting liquid withdrawn through the digester top
US4071399A (en) * 1976-09-01 1978-01-31 Kamyr, Inc. Apparatus and method for the displacement impregnation of cellulosic chips material
US4941944A (en) * 1984-07-13 1990-07-17 Pierre A. Tonachel Method for continuous countercurrent ogranosolv saccharification of comminuted lignocellulosic materials
US5547012A (en) * 1993-05-04 1996-08-20 Kamyr, Inc. Dissolved solids control in pulp production
AU690105B2 (en) * 1993-05-04 1998-04-23 Kamyr Inc. Dissolved solids control in pulp production
AU704580B2 (en) * 1993-05-04 1999-04-29 Kamyr Inc. Dissolved solids control in pulp protection
AU721103B2 (en) * 1993-05-04 2000-06-22 Kamyr Inc. Dissolved solids control in pulp protection
EP1873303A3 (en) * 1993-05-04 2008-06-18 Andritz Inc. Dissolved solids control in pulp production
US5985096A (en) * 1997-09-23 1999-11-16 Ahlstrom Machinery Inc. Vertical pulping digester having substantially constant diameter
US20020129911A1 (en) * 2000-10-16 2002-09-19 Marcoccia Bruno S. Process and configuration for providing external upflow/internal downflow in a continuous digester
RU2486302C2 (ru) * 2008-03-20 2013-06-27 Метсо Пейпер Свиден Актиеболаг Система подачи, включающая насосы в параллельной компоновке, для варочного котла непрерывного действия
RU2490385C2 (ru) * 2008-03-20 2013-08-20 Метсо Пейпер Свиден Актиеболаг Система подачи, содержащая параллельно установленные насосы, для варочного котла непрерывного действия
US11162218B1 (en) 2020-09-30 2021-11-02 Robert Clayton Biomass pulp digester

Also Published As

Publication number Publication date
FI40678B (enrdf_load_stackoverflow) 1968-12-31
DE1517143A1 (de) 1969-05-14
NO118248B (enrdf_load_stackoverflow) 1969-12-01

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