US2640774A - Production of cellulose pulp - Google Patents

Production of cellulose pulp Download PDF

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Publication number
US2640774A
US2640774A US105162A US10516249A US2640774A US 2640774 A US2640774 A US 2640774A US 105162 A US105162 A US 105162A US 10516249 A US10516249 A US 10516249A US 2640774 A US2640774 A US 2640774A
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United States
Prior art keywords
steam
pressure
plant material
chips
digester
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Expired - Lifetime
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US105162A
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English (en)
Inventor
Ross James Hamilton
Hart John Semple
Strapp Richard Kevin
Maass Otto
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FPInnovations
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Pulp and Paper Research Institute of Canada
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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
    • D21C1/00—Pretreatment of the finely-divided materials before digesting
    • D21C1/02—Pretreatment of the finely-divided materials before digesting with water or steam
    • 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
    • D21C1/00—Pretreatment of the finely-divided materials before digesting
    • D21C1/10—Physical methods for facilitating impregnation

Definitions

  • This invention relates to the production of cellulosepulp from plant materials
  • the estimation inthe pretreatmentiproceduret may bea; relatives point may be defined as that. state: in which: the 'iylow superatmospheric pressure. anda there is cavity" of the fibre is entirely free from: liquid nonecessityof-maintainingthe: maximiun steam moisture and its well is saturated? throughout; pressure for any appreciable period following It i sat this saturation-r point that a1 wo'ocl fibre 49 attainment tl'iereofi commences to shrink on drying and exhibits its practice ithas been found.
  • the steam pressure he maintained at this upper limit only momentarily in order to reduce to a minimum adverse effects of this high pressure steaming on the structure of the cellulose in the Wood and on the solubility of the lignin and other .binding substances in normal pulping liquors.
  • the lower limit to which the pressure in the pressure vessel is reduced during pretreatment of-the chips may be any pressure which can conveniently be arrived at within an allotted period of time suitable for economical commercial operation and which will give the required differential between the upper and lower limits of pressure. At this point, it may be noted that the efficiency of the pretreatment procedure increases with an increase in the rate at which the pressure is dropped from the upper to the lower limit.
  • the lower limit of pressure may be superatmospheric, zero or subatmospheric.
  • the mechanism of the pretreatment procedure may be explained as follows: During filling of the pressure vessel with steam to establish therein the selected upper limit of steam pressure and temperature, the wood chips are heated to the temperature of the surrounding steam which penetrates the chips to some extent. During the ensuing rapid reduction of the steam pressure to the selected lower limit, the water within the wood chips is flashed into steam and flows out of the chips with considerable velocity. This high velocity outflow of steam from within the wood chips serves to efiiciently purge the latter of air, free water and certain penetration-retarding solids which are entrained and removed by the outflowing steam.
  • the pretreatment procedure has the peculiar characteristic that it results in the moisture content of the chips being brought to or very close to the fibre saturation point by either increasing or decreasing the original moisture content of the chips.
  • the pretreatment adds the required amount of moisture in the form of absorbed water.
  • the pretreatment brings the moisture content close to the fibre saturation point by removing free water.
  • Repetition of the pretreatment proceedur is desirable and, in many cases, necessary to bring the moisture content of the pretreated chips sufiiciently close to the fibre saturation point and to efiect substantially complete purging of the chips of air, free water, and certain other penetration-retarding substances.
  • a single application of the pretreatment procedure may give commercially satisfactory results but, as a general rule, two or more applications of the pretreatment procedure will be found necessary to obtain the optimum results.
  • excessive repetition of the pretreatment procedure may have detrimental effects on the cellulose and should be avoided.
  • the predetermined procedure which constitutes the basic novel feature of the invention serves, by its unique moisture-content regulating efiect and its eflicient removal of penetration-retarding substances, to place the chips in the optimum condition for rapidly absorbing and uniformly distributing throughout their structure or tissue the defibrating reagents contained in the cooking or pulping liquor. It is also important to note that these results are obtained without in any way adversely affecting the pulp making qualities of the chips.
  • the wood chips After being pretreated in accordance with the present invention the wood chips are rapidly and uniformly impregnated with the cooking liquor and heated to a pulping reaction temperature by one of several alternative procedures, the selection of which is dependent on such factors as the nature or species of the pretreated chips, the kind of pulp desired, and the type of cooking liquor used.
  • Figure l is a graph showing the moisture content regulating effect of a typical pretreatment procedure to which the raw material is subjected in accordance with the invention prior to being impregnated with the cooking liquor and heated to a pulping reaction temperature;
  • Fig. 2 is a sectional View of a typical digester or pressure vessel which may be employed in the commercial application of the invention.
  • the graph (Fig. 1) shows the moisture regulating efiect obtained in a laboratory experiment by subjecting Douglas fir chips of widely varying original moisture content to four successive applications of the pretreatment purging procedure.
  • each: application or the: pretreatment procedure the: cycle: of: raising the: stem pressure the pressurevessel'. to: the? upper. limit ('40 lbs. per square inch): andi quickly reducing: it: to therlowerf limit lbs; pensduarez inch; was' com:- pleted; in: approxi'matelv three minutess. It will be: HOtBdz that this-2 pretreatment incneasedl the moisture: contents oi. chips: having; an; content? of from; 0% to 25%; and. reduced to 401% the moisture: content of: chips; having.
  • pretreats mentprocedure With. reference to repetitionof. the pretreats mentprocedure, it-has-also been. established; that wood with. moisture contents normally en:- countered as well. aswater soaked: woods. may be efiiciently: purged. of penetration-retarding; substances and. brought to a. uniform; moisture: cone tent closely approaching, the fibre saturation point-by: from .twoto -four. applications of the pretreatment procedure.
  • valves.- l 4, and. t6) are closed and. cooking; liquor: is introduced intothe. digester through aevalve. 2D to commence( the impregnation and pulping-re? action. stages of the complete processfor: the productiozn of. cellulose pulp;
  • the impregnation andi pulping of. the wood chips may be carriedoutasa single-stage operation in which impregnation-takes placewhile thacooking liquor in. the digester. isbeine gradually heated: up to attain. pulpingereaction temperatures: and pressures; Im this. case;, the pretreatment of the: chips ensures that, ..bw'the. time pulping: reaction conditions are obtained in the digester,, the; chips; will. be unitormly penetrated by the pulping; or chemicalareagentsiof the'cools ing liquor. to-a much greater degree thamheretoforelw-iththe result thatzthe pulp produced will be: of. a.
  • the impregnation and pulping of the chips may also be carried out in such manner as to constitute essentially a two-stage operation. Precautions are taken to maintain the temperature of the cooking liquor below the pulping-reaction temperature until it has been .determined that the chips have absorbed and uniformly distributed throughout their structure the full amount of defibrating chemicals of the cooking liquor which the chips are capable of absorbing and distributing throughout their structure. The contents of the digester are then heated up to attain pulping reaction conditions of temperature and pressure. This two-stage procedure gives a greater margin of safety with reference to ensuring that all the chips are uniformly impregnated to the fullest possible extent before being subjected to pulping-reaction conditions of temperature and pressure.
  • the partially exhausted liquor which is withdrawn from the digester when the chips are completely impregnated is fortified and brought back to its original strength by the addition of white liquor.
  • Part of the cooking liquor is then preferably withdrawn from the digester through the bottom strainer 15 and valve I6 before heating up the contents of the digester to attain pulping reaction temperatures and pressures.
  • the volume of liquor withdrawn from the digester following the impregnation of the chips maybe any desired proportion of the total volume of liquor introduced into the digester.
  • the chips since the chips have been fully impregnated, there is no necessity for retaining a large volume of excess liquor in the digester during the heating of the digester content to pulping reaction temperatures and considerable time and heat may therefore be saved by withdrawing from the digester, following impregnation of the chips, all but a very small amount of the excess liquor.
  • the small amount of excess liquor retained in the digester is substantially uniformly distributed among the chips during the actual cooking operation by steam distribution and by conventional liquor ciroulating methods.
  • the pressure employed in the pressure impregnation of the chips may be varied within wide limits ranging, for example, from about 20 lbs. per square inch to lbs. per square inch or higher. In a number of instances the chips were impregnated at a pressure of 100 lbs. per square inch and results were entirely satisfactory. However, in other instances, commercially satisfactory results were also obtained by impregnating the chips at an impregnating pressure of 20 lbs. per square inch. So far as can be determined from the results of numerous experimental and commercial applications of the invention, there appears to be no particular advantage in using impregnating pressures above 100 lbs. per square inch but it is possible that extended applications of the invention may disclose instances in which use of higher pressures may develop some advantages.
  • the ratio of the strength of the partially exhausted liquor withdrawn from the digester upon completion of impregnation appears to vary according to the original strength of the liquor and the temperature at which the impregnation takes place and this consideration should be borne in mind in determining the strength of the original cooking liquor.
  • Another advantage of the present invention is that it lends itself to the uniform pulping of a mixture of woods of different species which cannot be uniformly pulped by conventional pulping procedures. By carrying out the pretreatment, impregnation and pulping reaction procedures as prescribed by this invention, it has been found possible to produce a uniform pulp of commercially satisfactory quality from a mixture of jack pine and poplar wood chips mixed together in equal proportion by Weight.
  • valves 14 and I6 were immediately opened to reduce the steam pressure in the digester to 10 lbs. per sq. in. as rapidly as possible. This reduction of steam pressure required approximately 6 minutes.
  • the valves M and I6 were closed and steam valve 8 again opened to again raise the steam pressure in the digester to 20 lbs. per sq. in. This second raising of the steam pressure to the specified upper limit reace-emu 9 uu-ired approximately minutes.
  • the cooking liquor used was a regular hra-ft cooking liquor of approximately 30% *stilphidity .and cont lug approximately .l'6f5'% active alkali.
  • a sufilcient amount oi the surplus cooking liquor was then immediately withdrawniromthe ldigester to reduce the liquor to wood ratio to about 2.3 to 1, calculated on the basis of the bone dry weight of the wood.
  • the contents of the digester were ⁇ thenheateiil to Ctin lfiminutes and this temperature was maintained for hours. This operation produced a total yield 53.2% of good quality uniformly cooked pulpwtdth a screen yield of approximately 53%.
  • the pulp was QUi'bBBOft with no evidence of burning.
  • the chips had taken up the maximum amoimt of acid which they were capable of absorbing and side relief of "the di- "gester was resorted to fora period'of -15 minutes.
  • fl he temperature of the digester contents was thenraised tOfiPDlOXllll-EISGIY Mo -C. the shortest possible time that the system would permit by -introduction :of steam. This required about 21 05 ;minutes:and the temperature was'maintained cat-the :level of i '6. :for ':a further period "of '20 minutes. A further period of 30 minutes was used up in reducing the pressure in the digester.
  • the digester used in Example III was a conventional sulphite digester of approximately ten tons accepted pulp capacity and was provided with a conventional hot acid cooking system. With a digester of this type the normal time required for completion of a cock, as measured from the commencement of steaming until the blowdown, was 7 hours.
  • each chip is, in fact. its own digester.
  • the species more easily pulped does not have access, after delignification, to a continuing supply of chemical. and so further degrading of the pulp does not take place.
  • the result is, therefore, a uniform product from a mixture of species. It may be again emphasized that the conditioning of the chip to its constant moisture saturation value, coupled with its ability to subsequently receive an adequate amount of chemical in solution is an essential feature of this process.
  • the process which consists of the steps of introducing plant material in subdivided condition into a pressure vessel; displacing air in said pressure vessel with steam; subjecting said plant material within said pressure vessel to a pre-treating operation which comprises introducing steam under pressure to establish within the capilliary interstices of the plant material a mixture of air and steam until a pressure of from about five to about fifty pounds per square inch gage pressure is reached, then discontinuing the introduction of steam, and while excluding additional air from said pressure vessel forthwith rapidly withdrawing said mixture of air and steam from said pressure vessel and from the interstices of said plant material until a pressure is reached within the range of from atmospheric pressure to a gage pressure half that which existed when the introduction of steam was discontinued; thereafter immersing said pro-treated plant material in cooking liquor while continuing to exclude air from said plant material, the quantity of cooking liquor being sufiicient to completely submerge said pre-treated plant material; withdrawing a substantial portion of the cooking liquor surrounding said plant material; and then

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  • Paper (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
US105162A 1953-01-27 1949-07-16 Production of cellulose pulp Expired - Lifetime US2640774A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2314/53A GB727191A (en) 1953-01-27 1953-01-27 Improvements in or relating to the production of cellulose pulp from plant materials

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US105162A Expired - Lifetime US2640774A (en) 1953-01-27 1949-07-16 Production of cellulose pulp

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US (1) US2640774A (Direct)
CH (1) CH315332A (Direct)
DE (1) DE1031114B (Direct)
FR (1) FR1078481A (Direct)
GB (1) GB727191A (Direct)
NL (1) NL98149C (Direct)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2749240A (en) * 1953-01-17 1956-06-05 Pulp Paper Res Inst Production of cellulose pulp
US2799579A (en) * 1953-06-22 1957-07-16 Hjalmar S Messing Apparatus for presoaking lignocellulose material
DE1052796B (de) * 1956-01-18 1959-03-12 Pulp Paper Res Inst Verfahren zur kontinuierlichen oder diskontinuierlichen Gewinnung von Zellstoff aus Holz
DE1063450B (de) * 1956-05-11 1959-08-13 Bauer Bros Company Verfahren und Vorrichtung zur Vorbereitung von Holzschnitzeln oder aehnlichen zellulosehaltigen Rohstoffen zwecks Gewinnung von Halbzellstoff oder Zellstoff
US2932600A (en) * 1953-02-25 1960-04-12 Brown And Root Inc Process for the production of pulp from bagasse
US2985236A (en) * 1957-03-27 1961-05-23 Celleco Ab Impregnation of wood chips
US3013933A (en) * 1953-01-28 1961-12-19 Rayonier Inc Method for preparation of wood cellulose
US3016088A (en) * 1954-09-07 1962-01-09 Bauer Bros Co Rapid cycle digester
US3067086A (en) * 1959-09-15 1962-12-04 Columbia Cellulose Company Ltd Pulping process
US3078208A (en) * 1958-09-11 1963-02-19 Stora Kopparbergs Bergslags Ab Method for the production of neutral sulfite pulp
US3215587A (en) * 1963-01-21 1965-11-02 Lummus Co Continuous process and apparatus for delignification of cellulosic material
US3294625A (en) * 1963-03-28 1966-12-27 Lummus Co Method for impregnating cellulosic material
US4634499A (en) * 1983-05-02 1987-01-06 The Procter & Gamble Company Sulfite process for making pulp having a tactile softness from hardwood chips
US4734162A (en) * 1985-08-14 1988-03-29 The Procter & Gamble Company Hardwood pulp having a tactile sense of softness, and tissue paper webs thereof
US6129816A (en) * 1997-10-24 2000-10-10 Andritz-Ahlstrom Inc. Tapered screen assembly for a cellulose pulp digester
CN113355935A (zh) * 2021-06-22 2021-09-07 中国联合装备集团安阳机械有限公司 一种造纸行业用外置式装锅器、蒸煮锅及其使用方法
CN115053033A (zh) * 2020-02-03 2022-09-13 瑞典乙醇化工技术有限公司 用于生物质的预处理的设备和方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1034968B (de) * 1956-01-11 1958-07-24 Hans Werner Meyer Kontinuierliches Verfahren zum chemischen Aufschluss von zellulosehaltigen Faserstoffen zu Zellstoff oder Halbzellstoff und Vorrichtung zu dessen Durchfuehrung

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US369836A (en) * 1887-09-13 blackman
US480334A (en) * 1892-08-09 Hermann xdelbert alfred
US530635A (en) * 1894-12-11 blackman
US1138907A (en) * 1914-01-21 1915-05-11 John Herman Thickens Process of preparing wood fiber.
US1771598A (en) * 1925-07-11 1930-07-29 Sidney D Wells Process for digesting fibrous material
US1887899A (en) * 1921-03-28 1932-11-15 Bradley Mckeefe Corp Production of pulp
US1979341A (en) * 1929-04-11 1934-11-06 Cellulose Res Corp Process for preparing cellulose
US1996797A (en) * 1930-11-26 1935-04-09 Dreyfus Henry Production of cellulosic products
US2007341A (en) * 1929-02-13 1935-07-09 Cellulose Res Corp Process of treating cellulose fibers

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE288018C (Direct) *
DE282050C (Direct) *
DE304214C (Direct) * 1916-10-19
DE413268C (de) * 1924-06-01 1925-05-05 Hubert Braeunlich Verfahren zur Vorbehandlung von Holz oder aehnlichen Stoffen zum Zwecke der papier-Pappe-Herstellung o. dgl.
US2229886A (en) * 1934-12-19 1941-01-28 Chemipulp Process Inc Method of digesting fibrous materials
BE496841A (Direct) * 1949-07-12
CH291830A (de) * 1951-01-18 1953-07-15 Aktiebolag Wikmanshytte Bruks Verfahren zur Vorbehandlung von Holzschnitzeln zwecks Herstellung von Zellstoff.

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US369836A (en) * 1887-09-13 blackman
US480334A (en) * 1892-08-09 Hermann xdelbert alfred
US530635A (en) * 1894-12-11 blackman
US1138907A (en) * 1914-01-21 1915-05-11 John Herman Thickens Process of preparing wood fiber.
US1887899A (en) * 1921-03-28 1932-11-15 Bradley Mckeefe Corp Production of pulp
US1771598A (en) * 1925-07-11 1930-07-29 Sidney D Wells Process for digesting fibrous material
US2007341A (en) * 1929-02-13 1935-07-09 Cellulose Res Corp Process of treating cellulose fibers
US1979341A (en) * 1929-04-11 1934-11-06 Cellulose Res Corp Process for preparing cellulose
US1996797A (en) * 1930-11-26 1935-04-09 Dreyfus Henry Production of cellulosic products

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2749240A (en) * 1953-01-17 1956-06-05 Pulp Paper Res Inst Production of cellulose pulp
US3013933A (en) * 1953-01-28 1961-12-19 Rayonier Inc Method for preparation of wood cellulose
US2932600A (en) * 1953-02-25 1960-04-12 Brown And Root Inc Process for the production of pulp from bagasse
US2799579A (en) * 1953-06-22 1957-07-16 Hjalmar S Messing Apparatus for presoaking lignocellulose material
US3016088A (en) * 1954-09-07 1962-01-09 Bauer Bros Co Rapid cycle digester
DE1052796B (de) * 1956-01-18 1959-03-12 Pulp Paper Res Inst Verfahren zur kontinuierlichen oder diskontinuierlichen Gewinnung von Zellstoff aus Holz
DE1063450B (de) * 1956-05-11 1959-08-13 Bauer Bros Company Verfahren und Vorrichtung zur Vorbereitung von Holzschnitzeln oder aehnlichen zellulosehaltigen Rohstoffen zwecks Gewinnung von Halbzellstoff oder Zellstoff
US2985236A (en) * 1957-03-27 1961-05-23 Celleco Ab Impregnation of wood chips
US3078208A (en) * 1958-09-11 1963-02-19 Stora Kopparbergs Bergslags Ab Method for the production of neutral sulfite pulp
US3067086A (en) * 1959-09-15 1962-12-04 Columbia Cellulose Company Ltd Pulping process
US3215587A (en) * 1963-01-21 1965-11-02 Lummus Co Continuous process and apparatus for delignification of cellulosic material
US3294625A (en) * 1963-03-28 1966-12-27 Lummus Co Method for impregnating cellulosic material
US4634499A (en) * 1983-05-02 1987-01-06 The Procter & Gamble Company Sulfite process for making pulp having a tactile softness from hardwood chips
US4734162A (en) * 1985-08-14 1988-03-29 The Procter & Gamble Company Hardwood pulp having a tactile sense of softness, and tissue paper webs thereof
US6129816A (en) * 1997-10-24 2000-10-10 Andritz-Ahlstrom Inc. Tapered screen assembly for a cellulose pulp digester
US6375796B1 (en) 1997-10-24 2002-04-23 Andritz Inc. Method of treating material in a continuous digester
USRE39208E1 (en) * 1997-10-24 2006-08-01 Andritz, Inc. Method of treating material in a continuous digester
CN115053033A (zh) * 2020-02-03 2022-09-13 瑞典乙醇化工技术有限公司 用于生物质的预处理的设备和方法
CN113355935A (zh) * 2021-06-22 2021-09-07 中国联合装备集团安阳机械有限公司 一种造纸行业用外置式装锅器、蒸煮锅及其使用方法

Also Published As

Publication number Publication date
CH315332A (fr) 1956-08-15
NL98149C (Direct) 1961-06-15
DE1031114B (de) 1958-05-29
FR1078481A (fr) 1954-11-18
GB727191A (en) 1955-03-30

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