US3693380A - Apparatus for removal of entrained air from cellulose pulp before bleaching of the pulp - Google Patents

Apparatus for removal of entrained air from cellulose pulp before bleaching of the pulp Download PDF

Info

Publication number
US3693380A
US3693380A US99309A US3693380DA US3693380A US 3693380 A US3693380 A US 3693380A US 99309 A US99309 A US 99309A US 3693380D A US3693380D A US 3693380DA US 3693380 A US3693380 A US 3693380A
Authority
US
United States
Prior art keywords
pulp
conduit
tower
bleaching
gaseous
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 - Lifetime
Application number
US99309A
Other languages
English (en)
Inventor
Hans-Erik Rye Engstrom
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.)
HANS ERIK RYE ENGSTROM
Original Assignee
HANS ERIK RYE ENGSTROM
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
Application filed by HANS ERIK RYE ENGSTROM filed Critical HANS ERIK RYE ENGSTROM
Application granted granted Critical
Publication of US3693380A publication Critical patent/US3693380A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/1005—Pretreatment of the pulp, e.g. degassing the pulp
    • 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
    • D21C9/10—Bleaching ; Apparatus therefor

Definitions

  • a down-flow bleaching tower having a space under pressure at the top thereof is provided for bleaching cellulose pulp with a gaseous bleaching agent.
  • An inlet is provided at the top of the tower for introducing the gaseous agent in the space.
  • a first conduit, having an inlet for pulp containing entrained air, is connected to the inlet of a pump.
  • a second conduit, having an inlet connected to the outlet of the pump, introduces the pulp to the top of the tower against the pressure of the gaseous bleaching agent.
  • Pressure admitting means is connected to the outlet of the first conduit to force steam, oxygen, or a gaseous bleaching agent countercurrent to the pulp to expel and replace at least a portion of the entrained air in the pulp.
  • cellulose pulp is bleached with a gaseous bleaching agent, for example, oxygen, the bleaching agent being supplied to a downward-flow bleaching vessel, preferably a bleaching tower, into a space at the top of the tower above the column of pulp present in the vessel and the pulp falling down from the inlet opening of the tower being, within said space, subjected to a mechanical working, which has for its object partly to finely break up or disintegrate the pulp, partly to create a'circulation of gas within said space, in order that the reaction between the pulp and the gaseous bleaching agent should be facilitated.
  • a gaseous bleaching agent for example, oxygen
  • the bleaching process should be carried out at a high pulp consistency, for example, at 20 percent consistency.
  • Pulp of such a high consistency must, however, be transported to the inlet opening at the upper part of the bleaching tower and, the pressure in the tower at the pulp inlet opening preferentially being 8-10 kilopondslcm it is suitable to transport the pulp through a conduit to the inlet opening in question.
  • the most suitable means for effecting such pulp transportation is' a so-called thick stock pump. In connection with pulp transportation of the kind mentioned a great deal of air will accompany the pulp and, together with the latter, be introduced into the gas space at the top of the tower.
  • the present invention has for its object, by means of a special method and an apparatus for carrying out said method, to eliminate the above described drawbacks, at the same time providing for considerable advantages.
  • the new method in connection with the bleaching of cellulose pulp by means of a gaseous bleaching agent, for example, and preferably, by means of oxygen, in a downward-flow bleaching tower consists, fundamentally, therein that prior to feeding the pulp into a conveying means, for example, a thick stock pump, serving for transferring the pulp to the bleaching tower, a gaseous bleaching agent is supplied to the pulp in such a manner that air, contained in the pulp is wholly or partly, displaced and replaced by a gaseous bleaching agent, and that for carrying out the bleaching process an additional amount of gaseous bleaching agent, which may be required, is added to the pulp at some other place. This can preferably be done in a space at the top of the bleaching tower above the column of pulp in the tower.
  • An apparatus suitable for carrying out the method is characterized, fundamentally, by at least one conveyingmeans for feeding cellulose pulp of, preferably, high consistency to a bleaching tower, to which the conveying means may be connected by means of at least one conduit, furthermore at least one conduit, for supplying pulp to said conveying means and at least one conduit for supplying a gaseous bleaching agent to the pulp near the conveying means. Then the supplying of the gaseous bleaching agent is meantto take place in such a manner that .air, contained in the pulp, is gradually displaced and is, wholly or partly, replaced by the gaseous bleaching agent, which preferably is added in such an amount that part of it will leave together with the air displaced from the pulp. Preferably there is also at least one conduit for supplying bleaching agent at some other place.
  • the gaseous bleaching agent in accordance with the invention it is suitable to add the gaseous bleaching agent to the pulp immediately before the pulp enters the conveying means and then to adapt the amount of bleaching agent and the pressure in such a manner that the gaseous bleaching agent will, at least to a little extent,'be caused to flow counter the direction of feed of the pulp.
  • the amount of gaseous bleaching agent, added before the conveying means may be controlled automatically.
  • the gaseous bleaching agent may be added partly before the means for conveying the pulp to the bleaching tower, partly at the upper end of the tower and, furthermore, the gaseous bleaching agent may be added at an essentially lower pressure before the conveying means for the pulp .than in the bleaching tower itself.
  • some other gaseous bleaching agent and/or vapor preferably steam. If, for example, steam is used then heating of the pulp is obtained at the same time.
  • Numeral 1 indicates a bleaching tower, which may be a conventional downward-flow tower, provided with a supply conduit 2 for cellulose pulp, connected to the tower at the top thereof, and with an outlet conduit 3 for treated pulp, located at the bottom of the tower.
  • a conveying means which, in the embodiment shown, is presumed to consist of a socalled thick stock pump 6, to which the pulp is led from a filter 7, via a screw conveyor 8, a conduit 9 and a conduit 10 connected to the thick stock pump.
  • the conduits 9 and 10 may be replaced by one single conduit, which then preferably extends more straight to the thick stock pump 6.
  • the conduit 10 has a larger diameter than the conduit 9, which is, in the first place, due to the fact thatthe-conduit l0 encloses a screw conveyor 11.
  • a conduit 12 for a gaseous bleaching agent for example, oxygen and/or vapor, preferably steam.
  • the adding of a gaseous bleaching agent to the bleaching tower 1 also takes place through a conduit 13.
  • the bleaching tower usually being under a high pressure there is provided, on the upper portion of the tower, a conduit with a safety-valve l4.
  • Numeral indicates a movable, preferably rotatable, member adapted to work the pulp upon its entering the tower.
  • a control valve 16 For controlling the supply of gasand/or vapor (steam) to the conduit 12, which is connnected to the conduit 10 just before the thick stock pump 6, there is provided a control valve 16, which preferably is adapted to be controlled by a feeler 17 for feeling the concentration of the gaseous bleaching agent and/or vapor (steam) which may ascend within the conduit 9.
  • the feeler 17 preferably is located at a larger distance from the thick stock pump 6 than is the place of connection of the supply conduit 12 in the neighborhood of said pump.
  • the plant When using, for example, oxygen as a bleaching and air-displacing agent the plant operates in the following manner.
  • Dewatered cellulose pulp having a consistency of say about percent, leaves the filter 7 in order to be moved sideways by the screw conveyor 8 to the substantially vertical, long conduit (tube) 9 to the nearest portion of the conduit (screw trough) 10, where the pulp is caught by the screw conveyor 11 and is fed on into the thick stock pump 6 in order to be moved on to the bleaching tower l.
  • the pulp which is to be fed into the thick stock pump 6 by means of the screw conveyor 11 contains a great deal of air, which, wholly or partly, is displaced or replaced by oxygen arriving from the conduit 12. In that case some oxygen may ascend within the conduit 9 and the feeler 17 then gives an impulse for controlling this quantity of gas to a predetermined value.
  • a plant according to the invention is not restricted to the embodiment as shown andv described, but several modifications may be devised within the scope of the invention.
  • the supply conduit 12 for the gaseous medium need not be connected to the pulp supply conduit near the pulp conveying means 11 but it may, instead, have its connection located further away from the conveying means.
  • Apparatus for bleaching cellulose pulp with a gaseous bleaching agent comprising a down-flow bleaching tower having a space under pressure at the top thereof and a column of pulp beneath said s ace, means for introducing a gaseous bleaching agen into the tower, a first conveying conduit having an inlet for pulp containing entrained air and an outlet end, a pump means, a second conveying conduit for introducing pulp to the top of the tower against the pressure of the gaseous bleaching agent therein, said pump means interconnecting said conveying conduits, means adjacent the outlet end of said first conveying conduit and ad jacent said pump for introducing a fluid under such pressure that fluid is forced to flow counter-current to the pulp passing through said first conveying conduit, said fluid being selected from the group consisting of steam, oxygen and a gaseous bleaching agent, the fluid, which flows counter-current to the pulp expelling and replacing at least a portion of the entrained air in the pulp.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
  • Structure Of Emergency Protection For Nuclear Reactors (AREA)
US99309A 1967-11-10 1970-12-17 Apparatus for removal of entrained air from cellulose pulp before bleaching of the pulp Expired - Lifetime US3693380A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE15463/67A SE333299B (sv) 1967-11-10 1967-11-10 Foerfarande vid och anordning foer blekning av foeretraedesvis cellulosamassa med gasformigt blekmedel

Publications (1)

Publication Number Publication Date
US3693380A true US3693380A (en) 1972-09-26

Family

ID=20300683

Family Applications (2)

Application Number Title Priority Date Filing Date
US99309A Expired - Lifetime US3693380A (en) 1967-11-10 1970-12-17 Apparatus for removal of entrained air from cellulose pulp before bleaching of the pulp
US130504A Expired - Lifetime US3668063A (en) 1967-11-10 1971-04-01 Removal of entrained air from cellulose pulp before bleaching of the pulp

Family Applications After (1)

Application Number Title Priority Date Filing Date
US130504A Expired - Lifetime US3668063A (en) 1967-11-10 1971-04-01 Removal of entrained air from cellulose pulp before bleaching of the pulp

Country Status (9)

Country Link
US (2) US3693380A (mo)
AT (1) AT300546B (mo)
DE (1) DE1807900A1 (mo)
FI (1) FI45571C (mo)
FR (1) FR1590979A (mo)
GB (1) GB1246512A (mo)
NO (1) NO129966B (mo)
SE (1) SE333299B (mo)
SU (1) SU367616A3 (mo)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2135217C3 (de) * 1970-07-24 1974-10-31 Sunds Ab, Sundsvall (Schweden) Verfahren und Vorrichtung zum Bleichen von Fasermaterial, insbesondere von Zellstoffpulpe
US4004967A (en) * 1972-06-22 1977-01-25 Billeruds Aktiebolag Bleaching cellulose pulp with oxygen in the presence of formaldehyde
SE391544C (sv) * 1974-12-10 1985-10-28 Billeruds Ab Sett for forcerad hartsmognad hos vedflis
US4172006A (en) * 1976-08-26 1979-10-23 Weyerhaeuser Company Method of delignifying wood chips with oxygen by adding cooking liquor under pressure
SE422818B (sv) * 1978-03-31 1982-03-29 Modo Chemetrics Ab Forfarande for foredling av allulosamassa genom blekning eller extrahering
US4232416A (en) * 1979-04-13 1980-11-11 Morton Machine Works, Incorporated Process for wetting fiber
US6126781A (en) * 1991-08-01 2000-10-03 Union Camp Patent Holding, Inc. Process for conditioning ozone gas recycle stream in ozone pulp bleaching
CA2078276C (en) * 1992-09-15 2004-05-25 Derek Hornsey Recovery of oxygen-rich gas from ozone bleaching processes
BR9708265A (pt) * 1996-03-26 1999-04-13 Sunds Defibrator Ind Ab Processo de deslignificação por oxigénio de pasta química em dois estágios

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2706390A (en) * 1952-10-18 1955-04-19 Kamyr Ab Bleaching plant
US2990710A (en) * 1958-10-13 1961-07-04 Improved Machinery Inc Pulp bleaching apparatus

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2147618A (en) * 1936-04-01 1939-02-14 West Virginia Pulp & Paper Com Method of bleaching pulp
US3074842A (en) * 1959-07-24 1963-01-22 Dorr Oliver Inc Treatment of unbleached cellulose pulps
US3313678A (en) * 1962-02-14 1967-04-11 Svenska Cellulose Aktiebolaget Bleaching of cellulose pulp in towers in completely filled and closed system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2706390A (en) * 1952-10-18 1955-04-19 Kamyr Ab Bleaching plant
US2990710A (en) * 1958-10-13 1961-07-04 Improved Machinery Inc Pulp bleaching apparatus

Also Published As

Publication number Publication date
US3668063A (en) 1972-06-06
NO129966B (mo) 1974-06-17
SU367616A3 (mo) 1973-01-23
FI45571C (fi) 1972-07-10
DE1807900A1 (de) 1969-12-11
FI45571B (mo) 1972-04-04
AT300546B (de) 1972-07-25
SE333299B (sv) 1971-03-08
GB1246512A (en) 1971-09-15
FR1590979A (mo) 1970-04-20

Similar Documents

Publication Publication Date Title
US3693380A (en) Apparatus for removal of entrained air from cellulose pulp before bleaching of the pulp
US5411633A (en) Medium consistency pulp ozone bleaching
US2858213A (en) Wood chip digestion
JPH02216289A (ja) セルローズ繊維材料を連続的に蒸解する方法
PL101511B1 (pl) Method of continuous bleaching and delignifying chemical paper-pulp
JP4292148B2 (ja) チップを含浸するための方法及び装置
US4944842A (en) Method for reducing contamination in pulp processing
US6106668A (en) Method for feeding comminuted fibrous material
EP0062539A1 (en) Method for oxygen delignification
US1962150A (en) Process and apparatus for dry lime treatment of liquors
JPS59144692A (ja) 木材パルプの改良漂白法
US4592804A (en) Method for pre-treating lignocellulosic material in two steaming zones
US1989571A (en) Method of and apparatus for bleaching and refining pulp
US20050087315A1 (en) Low consistency oxygen delignification process
US3622441A (en) Multiple discharge stock treatment apparatus and method
US3841961A (en) Method for the carbonation of sulphide-containing green liquor solutions
NO164046B (no) Apparatur for behandling av lignocellulosematerialer med nitrogenoxyd og oxygen.
US3595696A (en) Corn steeping process and apparatus
FR2227388A1 (en) Bleach tower for wood cellulose slurry - having a device to maintain a pressure difference between the bleach inlet and outlet
US4007082A (en) Kraft mill recovery system
US5853536A (en) Method for ozone bleaching of cellulosic pulp at low consistency
US5766414A (en) Method of bleaching cellulose pulp with peroxide under elevated pressure in a first vessel and atmospheric pressure in second vessel
JPH11323757A (ja) 細砕繊維性材料の供給方法およびシステム
US4853082A (en) Process for the activation and delignification of cellulose pulp
EP0309998B1 (en) A method in the activation of lignocellulosic material with a gas containing nitrogen dioxide