US20060151133A1 - Method and a plant for producing and treating wood fibres - Google Patents

Method and a plant for producing and treating wood fibres Download PDF

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Publication number
US20060151133A1
US20060151133A1 US10/544,699 US54469905A US2006151133A1 US 20060151133 A1 US20060151133 A1 US 20060151133A1 US 54469905 A US54469905 A US 54469905A US 2006151133 A1 US2006151133 A1 US 2006151133A1
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US
United States
Prior art keywords
chip
preheater
flue gases
scrubber
drier
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.)
Abandoned
Application number
US10/544,699
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English (en)
Inventor
Carl-Johan Soderberg
Ulrika Backlund
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.)
Valmet AB
Original Assignee
Metso Paper Sundsvall AB
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Filing date
Publication date
Application filed by Metso Paper Sundsvall AB filed Critical Metso Paper Sundsvall AB
Assigned to METSO PAPER SUNDSVALL AB reassignment METSO PAPER SUNDSVALL AB ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BACKLUND, ULRIKA, SODERBERG, CARL-JOHAN
Publication of US20060151133A1 publication Critical patent/US20060151133A1/en
Abandoned legal-status Critical Current

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    • 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

Definitions

  • the present invention relates to a method for producing and treating wood fibres in a plant comprising a fibre-producing part having a chip preheater and a beater used to free fibre from wood chips, according to the preamble of claim 1 , as well as a corresponding plant according to the preamble of claim 9 .
  • a continuous production process of board according to the dry and wet method comprises, among other things, a disintegration of the raw material to free fibre or fibre aggregate, which in the subsequent steps is coated with glue, dried, formed and pressed to a finished product, so-called board or wood fibre board.
  • the freeing of fibre from the raw material is today preferably carried out in a so-called thermomechanical process in one step or in a thermal and mechanical processing step in two separate phases.
  • the thermal part, heating of the raw material takes place inter alia in an alkalinizing device at a temperature of up to approx. 100° C., under atmospheric pressure, and then in a pressurized chip preheater at a temperature of approx. 150-190° C. under a pressure of approx. 4-13 bar(e).
  • the dwell time in the preheater may be between 1-10 minutes depending on prevailing process conditions and may be adjusted.
  • the thermal heating in the chip preheater preferably takes place by means of steam.
  • the mechanical processing takes place in a beater between beater discs where the final fibre freeing takes place in a state where temperature and pressure is higher than in adjacent process stages.
  • the dwell time of the wood chips raw material in the beater zone is very short.
  • the power that is converted to mechanical energy in connection with the mechanical processing transforms into heat in the beater zone and occurs as steam in the system, generated from the moisture in the raw material.
  • the fibre After the defibering in the beater, the fibre is transported to a pneumatic fibre drier where the drying process is performed by means of a large amount of air and a controlled entering air temperature of approx. 140-200° C., depending on the current fibre moisture included.
  • the dried fibre is then transported further to forming, pre-pressing and finally to final pressing of the board.
  • the wood emissions released during the process foremost in the chip preheater, are transported all the way from preheater via beater together with the fibre bulk to the drier, where the majority is separated from the fibre and finally accompanies humid drying air leaving the drier and out into the atmosphere.
  • These emissions contain, above all, volatile organic substances, so-called VOC (Volatile Organic Compounds), as well as formaldehyde.
  • VOC Volatile Organic Compounds
  • formaldehyde formaldehyde
  • the object of the present invention is to provide a method and a plant that reduce the emission discharges, foremost of VOC and formaldehyde, to the atmosphere, from the production process as well as from the finished product, the boards. Simultaneously, the capacity in the production plant should be maintained and so also the quality of the final product.
  • the method according to the present invention is characterized in that flue gases generated during the compression are disposed of through an outlet arranged in the compression zone.
  • the plant according to the present invention is characterized in that in the compression zone a flue gas outlet is arranged for disposal of evaporated moisture, which is generated upon the compression of the wood chips and which contains flue gases.
  • the disposal of the flue gases that are generated during the compression is achieved by conveying them back to the upper part of the chip preheater from which they then are disposed of together with other flue gases.
  • the flue gases may advantageously be conveyed to destruction, e.g., to incineration in a boiler, where the emissions transform to carbon dioxide and water.
  • the flow of flue gases can be controlled, and in this way, also the steam losses in the chip preheater can be controlled.
  • a so-called catcher agent may be added to the wood chips upon the feeding thereof into the beater.
  • a catcher agent is a chemical that is injected in order to bind some substance, in this case formaldehyde. It is previously known to add catcher agents in other places in the process. However, it is not previously known to add a catcher agent directly into the beater and at tests it has turned out that this is particularly efficient as for binding formaldehyde. Test results with a catcher agent added into the beater have demonstrated a reduction of formaldehyde content by 8-15% and also a clear improvement of perforator values in the final board.
  • the wood fibres produced and treated in the beater are sent to a drier part and then to a scrubber, and air leaving the drier part, on the way to the scrubber, is conveyed through a heat exchanger for air entering the drier part so that the air to the drier part is heated and the air to the scrubber is cooled.
  • a heat exchanger for air entering the drier part so that the air to the drier part is heated and the air to the scrubber is cooled.
  • water drops may advantageously be separated in the scrubber by a demister device. Additional cooling by supply of water is also possible.
  • FIG. 1 shows schematically a plant for production and treatment of wood fibres, comprising an embodiment example according to the present invention
  • FIG. 2 shows an embodiment example of a first part of the plant according to the present invention
  • FIG. 3 shows an embodiment example of a second part of the plant according to the present invention.
  • the plant for producing and treating wood fibres illustrated schematically in FIG. 1 , is included in the illustrated example as a part of a continuous process for producing board of material containing lignocellulose.
  • Such a plant comprises a plurality of stages.
  • the stages that are illustrated schematically in FIG. 1 includes a first stage having a fibre-producing part comprising a chip preheater 1 and a beater 2 for freeing fibres of wood chips, a second stage having a drier part 3 comprising, for instance, a cyclone, and a third stage in connection with the drier part and comprising a scrubber 4 , foremost intended for efficient particle separation in connection with the drying.
  • the drier part in itself may comprise a plurality of drying steps having a plurality of similar apparatuses and the plant may moreover also comprise additional intermediate steps and details that have not been shown for reasons of clarity.
  • the fibre-producing part of the plant in FIG. 1 is shown on a somewhat larger scale in FIG. 2 .
  • wood chips A are fed into the preheater 1 , usually from an alkalinizing bin, which is not shown.
  • steam B is supplied via steam inlets 7 .
  • the chip preheater is also provided with a top outlet 8 .
  • the wood chips are heated by means of condensing heat from the steam, which is supplied at pressure, temperature and time having been pre-set and adapted to the wood chips raw material.
  • the steam B is supplied into the lower part of the chip preheater, it will move up through the wood chips column C towards the colder entering wood chips in the top, and in this way the moisture in the wood chips is evaporated and forms steam containing released organic emissions from the wood. Said emissions, foremost organic volatile substances such as VOC and formaldehyde, are then separated at a high concentration in the top of the preheater via the top outlet 8 . Next, from the top outlet, the flue gases travel to some kind of destruction device, which is not shown. The destruction may, for instance, be effected by incineration or by evaporation.
  • the flue gas line in the top of the preheater is provided with temperature control device, TIC, and the supply line for steam is provided with a pressure control device, PIC.
  • TIC temperature control device
  • PIC pressure control device
  • the degassing in the top of the preheater has a favourable impact on the heat transfer between the steam and the wood chips in the preheater.
  • the air that is contained in the supplied cold wood chips A reduces said heat transfer, but by means of the present invention this air may instead be directly disposed of through the top outlet 8 .
  • a chip outlet 11 In the bottom of the chip preheater, there is a chip outlet 11 .
  • a screw conveyor 12 arranged, which feeds the wood chips to the beater 2 .
  • the screw conveyor comprises a compression zone 15 where the water is pressed out of the chip mass and the formed moisture evaporates in the zone so that steam is generated.
  • the compression zone 15 is formed by the shaft, of that part of the screw conveyor 12 that is closest to the beater 2 , having an increasing diameter, so that it obtains a conical shape. This results in the chip material in said part being compressed and pushed out against the outer walls of the screw conveyor 12 where a so-called plug flow is formed, which partly plugs up the entrance to the beater.
  • the formed plug separates the beater from the screw conveyor so that steam from the beater cannot travel rearwards into the compression zone.
  • a flue gas outlet 13 is arranged in the compression zone so that it is possible to dispose of said evaporated moisture, which contains flue gases.
  • said flue gas outlet is connected to a line 14 that conveys the flue gases back to the upper part of the chip preheater 1 .
  • they can then be disposed of together with other flue gases via the top outlet 8 and further away for destruction.
  • a catcher agent D is a chemical, which is injected in order to bind some substance, in this case formaldehyde.
  • the member 16 for addition of a catcher agent may, for instance, be formed so that the supply of the catcher agent D takes place via the centre of the screw conveyor 12 into the beater 2 .
  • a suitable catcher agent in this case may be urea or the like.
  • FIG. 3 an embodiment example is shown of a scrubber plant 4 according to the present invention, which is used in connection with a drier stage.
  • Said scrubber plant may advantageously be used together with the above-described chip preheater 1 and the beater 2 , but may also be used together with other types of chip preheaters and beaters and also in other types of plants, and may thus be regarded as an invention in itself.
  • a scrubber 4 is shown that receives air E that travels from the drier part 3 , via a line 28 . Before the same air is allowed to pass into the scrubber, it passes a heat exchanger device 20 , for instance, a tube heat exchanger, for the air F entering the drier.
  • a heat exchanger device 20 for instance, a tube heat exchanger
  • the heat that the air E leaving the drier contains is utilized in order to preheat the air F, G entering the drier, at the same time as the air leaving the drier is cooled down before it enters the scrubber 4 .
  • the equilibrium relationship between air temperature and the concentration of formaldehyde will consequently be altered and promotes the transfer of formaldehyde into water phase.
  • the air E leaving the drier may have a temperature of the order of +60° C.
  • the drying air F entering the heat exchanger is as a rule taken from outside and may then have a temperature of +10° C.
  • the preheated air G entering the drier may then have a temperature of +30° C.
  • the scrubber is also provided with a number of water sprayers 21 , which accordingly spray out water that cools and absorbs the emissions that are in the drying air into water phase.
  • Water sprayers 22 may advantageously also be positioned in the inlet line 26 to the scrubber.
  • In the lower part of the scrubber there is a water outlet 23 , where water is drawn off in order to be conveyed to purification.
  • In the top of the scrubber there is an outlet 24 for leaving air.
  • the scrubber is suitably also provided with a so-called demister or droplet separator 25 in connection with the upper air outlet, in order to separate water drops.
  • the supplied spray water may possibly be chemically treated with NaHSO 3 and NaOH in order to optimise the function of the emission reduction.
  • the scrubber 4 is provided with a device 27 for supply of said additives to the water. Test results have shown that in this way, a 75% reduction of the formaldehyde content in the leaving air is achieved, already without connection of a heat exchanger.

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Mechanical Engineering (AREA)
  • Drying Of Solid Materials (AREA)
  • Treating Waste Gases (AREA)
  • Dry Formation Of Fiberboard And The Like (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
US10/544,699 2003-02-11 2004-02-11 Method and a plant for producing and treating wood fibres Abandoned US20060151133A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE0300385-2 2003-02-11
SE0300385A SE524788C2 (sv) 2003-02-11 2003-02-11 Förfarande och anordning för framställning och behandling av träfiber
PCT/SE2004/000180 WO2004072362A1 (en) 2003-02-11 2004-02-11 A method and a plant for producing and treating wood fibres

Publications (1)

Publication Number Publication Date
US20060151133A1 true US20060151133A1 (en) 2006-07-13

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US10/544,699 Abandoned US20060151133A1 (en) 2003-02-11 2004-02-11 Method and a plant for producing and treating wood fibres

Country Status (8)

Country Link
US (1) US20060151133A1 (ru)
EP (1) EP1597427A1 (ru)
CN (1) CN1748057A (ru)
BR (1) BRPI0407339A (ru)
CA (1) CA2512993A1 (ru)
RU (1) RU2345186C2 (ru)
SE (1) SE524788C2 (ru)
WO (1) WO2004072362A1 (ru)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090301673A1 (en) * 2005-12-02 2009-12-10 Vidar Snekkenes System and a method for the steam pre-treatment of chips in association with the production of chemical cellulose pulp

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
HRP20220416T1 (hr) * 2020-02-28 2022-05-27 Fiberboard Gmbh Postupak i sustav obrade radi smanjenje hlapljivih organskih spojeva iz drvene sječke
EP4122662B1 (de) 2021-07-23 2024-02-28 Fiberboard GmbH Verfahren zum herstellen von faserplatten unter verringertem voc-ausstoss

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4037792A (en) * 1972-10-23 1977-07-26 Sca Development Aktiebolag Continuously refining raw fibrous material to produce mechanical refiner pulp
US4059237A (en) * 1974-02-15 1977-11-22 Oy Keskuslaboratorio - Centrallaboratorium, Ab System for feeding a double disc refiner
US4082233A (en) * 1975-06-04 1978-04-04 Rolf Bertil Reinhall Disc refiner having means for removing gaseous media from pulp stock
US4136831A (en) * 1976-08-06 1979-01-30 Isel S.A. Method and apparatus for minimizing steam consumption in the production of pulp for fiberboard and the like
US4163525A (en) * 1977-01-03 1979-08-07 Reinhall Rolf Bertil Device for evacuating blow-back steam in pulp refining apparatus
US4219166A (en) * 1978-05-26 1980-08-26 Enso-Gutzeit Osakeyhtio Disk defibrator
US4298425A (en) * 1978-05-03 1981-11-03 Defibrator Aktiebolag Method and apparatus for refining lignocellulose-containing material to produce fiber pulp
US4421595A (en) * 1979-01-12 1983-12-20 Yhtyneet Paperitehtaat Oy Jylhavaara Process for preparing thermomechanical pulp with heat recovery
US4555254A (en) * 1982-11-30 1985-11-26 Koppers Company, Inc. Material collector and discharger apparatus
US5034175A (en) * 1987-12-16 1991-07-23 Sunds Defibrator Industries Aktiebolag Method and apparatus for manufacturing fiber board sheets
US6070655A (en) * 1996-06-07 2000-06-06 Valmet Corporation Heat exchanger
US6464826B1 (en) * 1997-08-25 2002-10-15 Valmet Fibertech Ab Method for producing and treating wood fiber

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4129166A (en) 1977-07-18 1978-12-12 General Electric Company Nb3 Ge superconductive films grown with air

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4037792A (en) * 1972-10-23 1977-07-26 Sca Development Aktiebolag Continuously refining raw fibrous material to produce mechanical refiner pulp
US4059237A (en) * 1974-02-15 1977-11-22 Oy Keskuslaboratorio - Centrallaboratorium, Ab System for feeding a double disc refiner
US4082233A (en) * 1975-06-04 1978-04-04 Rolf Bertil Reinhall Disc refiner having means for removing gaseous media from pulp stock
US4136831A (en) * 1976-08-06 1979-01-30 Isel S.A. Method and apparatus for minimizing steam consumption in the production of pulp for fiberboard and the like
US4163525A (en) * 1977-01-03 1979-08-07 Reinhall Rolf Bertil Device for evacuating blow-back steam in pulp refining apparatus
US4298425A (en) * 1978-05-03 1981-11-03 Defibrator Aktiebolag Method and apparatus for refining lignocellulose-containing material to produce fiber pulp
US4219166A (en) * 1978-05-26 1980-08-26 Enso-Gutzeit Osakeyhtio Disk defibrator
US4421595A (en) * 1979-01-12 1983-12-20 Yhtyneet Paperitehtaat Oy Jylhavaara Process for preparing thermomechanical pulp with heat recovery
US4555254A (en) * 1982-11-30 1985-11-26 Koppers Company, Inc. Material collector and discharger apparatus
US5034175A (en) * 1987-12-16 1991-07-23 Sunds Defibrator Industries Aktiebolag Method and apparatus for manufacturing fiber board sheets
US6070655A (en) * 1996-06-07 2000-06-06 Valmet Corporation Heat exchanger
US6464826B1 (en) * 1997-08-25 2002-10-15 Valmet Fibertech Ab Method for producing and treating wood fiber

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090301673A1 (en) * 2005-12-02 2009-12-10 Vidar Snekkenes System and a method for the steam pre-treatment of chips in association with the production of chemical cellulose pulp
US8052843B2 (en) * 2005-12-02 2011-11-08 Metso Paper Sweden Ab System and a method for the steam pre-treatment of chips in association with the production of chemical cellulose pulp

Also Published As

Publication number Publication date
BRPI0407339A (pt) 2006-01-10
CN1748057A (zh) 2006-03-15
EP1597427A1 (en) 2005-11-23
SE524788C2 (sv) 2004-10-05
SE0300385L (sv) 2004-08-12
RU2005128278A (ru) 2006-01-27
RU2345186C2 (ru) 2009-01-27
SE0300385D0 (sv) 2003-02-11
WO2004072362A1 (en) 2004-08-26
CA2512993A1 (en) 2004-08-26

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Legal Events

Date Code Title Description
AS Assignment

Owner name: METSO PAPER SUNDSVALL AB, SWEDEN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SODERBERG, CARL-JOHAN;BACKLUND, ULRIKA;REEL/FRAME:016666/0948

Effective date: 20050801

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION