WO1996007070A2 - Procede de sechage de matiere premiere pour fabriquer des panneaux de particules - Google Patents

Procede de sechage de matiere premiere pour fabriquer des panneaux de particules Download PDF

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Publication number
WO1996007070A2
WO1996007070A2 PCT/US1995/011164 US9511164W WO9607070A2 WO 1996007070 A2 WO1996007070 A2 WO 1996007070A2 US 9511164 W US9511164 W US 9511164W WO 9607070 A2 WO9607070 A2 WO 9607070A2
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WO
WIPO (PCT)
Prior art keywords
raw material
conveyor
dryer housing
drying air
drying
Prior art date
Application number
PCT/US1995/011164
Other languages
English (en)
Other versions
WO1996007070A3 (fr
Inventor
William Benny Teal
Original Assignee
William Benny Teal
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 William Benny Teal filed Critical William Benny Teal
Priority to AU36266/95A priority Critical patent/AU3626695A/en
Publication of WO1996007070A2 publication Critical patent/WO1996007070A2/fr
Publication of WO1996007070A3 publication Critical patent/WO1996007070A3/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/02—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by belts carrying the materials; with movement performed by belts or elements attached to endless belts or chains propelling the materials over stationary surfaces
    • F26B17/04—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by belts carrying the materials; with movement performed by belts or elements attached to endless belts or chains propelling the materials over stationary surfaces the belts being all horizontal or slightly inclined
    • F26B17/045—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by belts carrying the materials; with movement performed by belts or elements attached to endless belts or chains propelling the materials over stationary surfaces the belts being all horizontal or slightly inclined the material on the belt being agitated, dispersed or turned over by mechanical means, e.g. by vibrating the belt, by fixed, rotating or oscillating elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/02—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by belts carrying the materials; with movement performed by belts or elements attached to endless belts or chains propelling the materials over stationary surfaces
    • F26B17/08—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by belts carrying the materials; with movement performed by belts or elements attached to endless belts or chains propelling the materials over stationary surfaces the belts being arranged in a sinuous or zig-zag path

Definitions

  • This invention relates to a method for drying wood elements, and more particularly, to the drying of raw material for the manufacture of particleboard.
  • Particleboard is a wood based panel product, the raw material of which is various forms of wood, for example, planer shavings, chips or sawdust. Because the raw material may have a high moisture content, it must be dried before it is further processed into the final product. The raw material is therefore collected and fed into a dryer, after which it is discharged and refined, or ground up, and may be dried again. (The raw material may also be refined prior to being initially dried.) The refined and dried raw material is then blended with adhesive and formed into mats, for example, on caul plates or on a continuous conveyor. The mat of raw material is then separated into discrete lengths which are compressed and heated to produce panels.
  • the current method of drying raw material for particleboard manufacture is to feed the raw material into a rotary dryer. Such dryers tumble the raw material while exposing it to a flow of heated air, the inlet temperature of which is typically 800°F or higher.
  • the current method has several disadvantages.
  • One such disadvantage is the generation and emission of airborne pollutants.
  • pollutants include paniculate matter entrained in the drying airstream and gaseous pollutants such as carbon monoxide.
  • a conveyor dryer In accordance with a preferred embodiment of the present invention illustrated herein, wet raw material is fed onto a conveyor, thereby forming a loosely compacted bed of raw material.
  • the conveyor which includes means for allowing air to pass through it and therefore through the bed of raw material, moves the bed of raw material through a dryer housing.
  • a volume of drying air or other suitable gas is heated for use in the dryer.
  • heating may be accomplished in a variety of ways and may occur either internally or externally to the dryer, in a preferred embodiment, heat exchangers having thermal oil or steam coils are used, the oil or steam being heated by the combustion of bark and other waste wood.
  • the heated drying air is then forced or drawn through the bed of raw material and circulated through and around the conveyor to dry the raw material.
  • the dryer housing may be configured into one zone or it may be partitioned into several zones, such that the direction and temperature of the drying air in each zone may be controlled separately. For example, warm air may be forced upward through the bed of raw material in a first zone, downward through the bed in a second zone and then upward again in a third zone, the temperature in each zone gradually decreasing.
  • the direction of the air is accomplished in an embodiment illustrated herein by positioning and regulating fans and dampers.
  • a volume of the heating air is recycled, thereby more efficiently using the thermal energy present in the drying air and thereby reducing the volume of air expelled to the atmosphere as exhaust.
  • the dried raw material is then discharged from the dryer housing.
  • the dried raw material is passed through a conditioning zone before being discharged.
  • the conveyor may be configured in a "single pass" whereby the raw material is conveyed in a substantially straight line path through the dryer.
  • the conveyor may be partitioned into sections, each section being positioned at different elevations such that the raw material is forced to fall from one conveyor section to the next at a lower elevation.
  • Such a "multi-pass" system occupies less floor space than a single- pass system, and also serves to agitate the raw material, thereby promoting even exposure to the drying air. Agitation in either a single- or multi-pass configuration may be accomplished by exposing the raw material to a suitable turnover device.
  • Figure 1 is a flow chart illustrating the steps of a preferred embodiment of the present invention.
  • Figure 2 is a diagram illustrating a dryer in accordance with a preferred embodiment of the present invention.
  • Figure 3 is a diagram illustrating a dryer in accordance with an alternative embodiment of the present invention.
  • Figure 4a is a sectional end view taken through a zone of the dryer of Figure 2.
  • Figure 4b is a sectional end view taken through a zone of the dryer of Figure 2.
  • Particleboard is composed of wood "waste" material, for example, planer shavings, chips or sawdust. This raw material is refined, dried, possibly refined again, coated with adhesive, pressed, and otherwise formed to create a finished board or panel product. Under current methods, raw material for the manufacture of particleboard is dried in a rotary dryer. However, there are several disadvantages to this method, including the generation and emission of a high volume of exhaust and pollutants. These problems, among others, are reduced by drying raw material for the manufacture of particleboard in accordance with the present invention.
  • Figure 1 illustrates the steps comprising a preferred embodiment of the present invention, whereby raw material for the manufacture of particleboard is dried in a conveyor dryer.
  • the raw material may be dried more than once during the manufacturing process both before and after being screened and refined.
  • the present invention is applicable to every stage of the process in which the raw material is to be dried.
  • Commercially available conveyor dryers such as those manufactured by Proctor & Schwarz of Horsham, Pennsylvania, are suitable for raw material drying in accordance with the present invention.
  • the raw material is fed onto a conveyor 26 or 11, step 10. Although this may be accomplished by a variety of means, in a preferred embodiment, the raw material is fed onto the conveyor by an oscillating belt or screw conveyor (not shown).
  • the raw material is conveyed through a dryer housing 28, step 12, and will follow different paths depending on the configuration of the system.
  • a single pass configuration 25 is illustrated in Figure 2, wherein the raw material is conveyed through the dryer housing 28 in a straight line path.
  • An alternative embodiment is illustrated in Figure 3, wherein a multipass configuration 27 conveys the raw material along a first level, after which the raw material drops to a second level or section of the conveyor before being discharged from the dryer housing, step 20.
  • a volume of drying air is heated, step 14.
  • heat exchangers having thermal oil or steam coils 35 are used, the oil or steam being heated by the combustion of bark and other waste wood.
  • the temperature of the drying air may be set at any level in the preferred embodiment illustrated herein, it is set at a temperature between ambient and 600°F.
  • the drying air is passed through the bed of raw material, step 16, in either an upward or a downward direction.
  • the direction of the drying air is controlled by the particular arrangement of fans, partitions and dampers, as illustrated in Figures 4a and 4b.
  • Figure 4a is a sectional end view taken through drying zone 19 of Figure 2 wherein the drying air is forced downward through the bed of raw material 46 on conveyor 11.
  • the relative positioning of intake 47a, fan 48a and partitions 49a, 50a and 51a serve to direct the airflow. More specifically, a volume of drying air is drawn into the drying zone 19 from a supply duct (not shown) at 47a by a fan 48a which then exhausts the drying air, forcing it down through the heat exchanger coils 35a and bed of raw material, thereby evaporating moisture from the raw material.
  • a portion of the moisture-laden air is exhausted at 52a while the remainder is drawn back through fan 48a along with additional drying air.
  • a relatively large volume of the drying air is recirculated, thereby making efficient use of the thermal energy in the drying air and minimizing the amount of air that exits the dryer housing 28 as exhaust.
  • Figure 4b is a cross-sectional end view taken through drying zone 21 of Figure 2 wherein the drying air is directed upward through the bed of raw material 46 on the conveyor 13. A volume of drying air is drawn into zone 21 at 47b by fan 48b which then exhausts the drying air into a plenum created between the partition 51b and the dryer housing 28. The drying air is then forced through heat exchanger coils 35b and beneath and up through the conveyor 13 and bed of raw material 46, thereby evaporating moisture from the raw material. While a portion of the moisture-laden air is exhausted at 52b, the remainder is recirculated in a manner similar to the pattern illustrated in Figure 4a.
  • dampers are used at an entrance 47 and an exit 52 of a drying zone, and between partitions 49 and 50, to further regulate airflow.
  • the fans, partitions and dampers may be configured in drying zone 21 as illustrated in Figure 4a.
  • the dryer housing may be partitioned into multiple zones, step 22, which zones may be drying zones 19, 21, 23, 30, 32, 34 and/or conditioning zones 36.
  • the drying zones 19, 21, 23 are separated by buffer zones 31, 33 defined by partitions within the dryer housing 28.
  • the buffer zones allow access to the dryer at various points along the dryer path for inspection and maintenance.
  • the raw material may be either heated or cooled, depending on whether it is desirable for the raw material to exit the dryer at a temperature that is higher or lower than the temperature it would be at if it was discharged from the dryer immediately following the completion of the drying process. For example, it may be desirable for the raw material to exit the dryer at a relatively high temperature, thereby potentially increasing the thermal efficiency of the pressing process.
  • the raw material would therefore be heated in a conditioning zone.
  • the heating or cooling of the raw material in a conditioning zone is accomplished in accordance with the present invention by controlling the temperature of the air in the conditioning zone, similar to controlling the temperature of the drying air.
  • the temperature in a given zone may be controlled independently of the other zones.
  • a depth of a bed of raw material and the retention time, or amount of time the raw material remains in the housing may be controlled.
  • the drying process may be accurately controlled to gradually and evenly dry the raw material.
  • the required retention time will depend on the moisture content of the wood, which may vary with the species of wood and time of season, among other factors.
  • the moisture content of the wood may be monitored, however, by periodically measuring the moisture content of the raw material and/or periodically sampling the raw material. (A commercially available moisture meter, such as those manufactured by Moisture Systems, Inc., is suitable for measuring the moisture content of the raw material in accordance with the present invention.) In this manner, the raw material is dried evenly and efficiently.
  • raw material for the manufacture of particle board may be dried by passing it through a single pass, single zone wherein the temperature is 350°. Because fewer pollutants such as carbon monoxide are produced at lower temperatures, this reduction in operating temperature should significantly reduce the level of pollutants emitted to the atmosphere. This ability to achieve good results at lower temperatures is due in part to the fact that unlike prior art rotary dryers, it is possible to accurately control and lengthen the retention time when drying raw material in accordance with the present invention.
  • the raw material In a rotary dryer, the raw material is showered into an entrance of a large, rotating drum. As the drum rotates, the raw material is lifted toward the top of the dryer to fall through the drying air stream. The rotational movement of the drum and the motion of the drying airstream advance the raw material through the dryer housing. When the raw material reaches the end of the drum, it falls into a collection bin. Because a minimum quantity of air flow is required to remove the moisture from the system and a minimum speed of rotation of the drum is required to adequately expose the raw material to the airstream, it is very difficult to slow down the progression of the raw material through the dryer to accurately control the retention time. As a result, if the temperature is reduced in a prior art rotary dryer, the raw material is not adequately dried before being discharged. In contrast, the present invention allows complete control of the retention time, such that the temperature may be lowered and the retention time increased sufficiently to adequately dry the raw material before discharging it from the dryer.
  • the velocity of drying air passing through and around the raw material is considerably less than the velocity of air in a rotary dryer, which is believed to also significantly reduce the emission of pollutants by reducing the volume of fines that are entrained in the airstream.
  • the raw material is agitated as it passes through the dryer housing 28, step 24, thereby promoting the even exposure of the raw material to the drying air.
  • This agitation may be accomplished in a variety of ways.
  • the raw material may be agitated as it falls from one level of the conveyor to a second level of the conveyor, as illustrated in Figure 3.
  • the raw material is conveyed through the dryer housing 28 by three independently driven conveyors 1 1, 13, 15.
  • the raw material is received by a turnover device 42 comprising an inclined conveyor, which may be independently driven or driven by takeoff from either conveyor 11 or 13.
  • the raw material then moves upwards and fall from turnover device 42 onto conveyor 13, thereby being agitated.
  • a similar step is repeated between drying sections 21 and 23 by turnover device 44.
  • the raw material may be conveyed through a conditioning zone, as discussed above, step 18, before being discharged from the dryer housing, step 20.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

L'invention concerne un procédé de séchage de matière première pour fabriquer des panneaux de particules. Dans un mode de réalisation préféré, la matière première est amenée sur un convoyeur (11) qui la déplace comme un lit à travers un tunnel de séchage (28). Ce dernier peut être compartimenté en différentes zones et différents niveaux en fonction de la configuration souhaitée. Un volume d'air de séchage est réchauffé et envoyé à travers le lit de matière première, afin d'en réduire la teneur en humidité. Dans un mode de réalisation préféré, la matière première est agitée, afin de l'exposer de manière uniforme à la chaleur de séchage. Elle est ensuite transportée à travers une zone de traitement (36) avant d'être évacuée du tunnel de séchage.
PCT/US1995/011164 1994-09-01 1995-09-01 Procede de sechage de matiere premiere pour fabriquer des panneaux de particules WO1996007070A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU36266/95A AU3626695A (en) 1994-09-01 1995-09-01 Method for drying raw material for the manufacture of particleboard

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US29973894A 1994-09-01 1994-09-01
US08/299,738 1994-09-01

Publications (2)

Publication Number Publication Date
WO1996007070A2 true WO1996007070A2 (fr) 1996-03-07
WO1996007070A3 WO1996007070A3 (fr) 1996-04-11

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Application Number Title Priority Date Filing Date
PCT/US1995/011164 WO1996007070A2 (fr) 1994-09-01 1995-09-01 Procede de sechage de matiere premiere pour fabriquer des panneaux de particules

Country Status (2)

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AU (1) AU3626695A (fr)
WO (1) WO1996007070A2 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2511807C2 (ru) * 2012-06-06 2014-04-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Воронежский государственный университет инженерных технологий" (ФГБОУ ВПО "ВГУИТ") Сушилка для сыпучих материалов
EP2940414A1 (fr) * 2014-04-29 2015-11-04 ESG Kräuter GmbH Procédé et dispositif de séchage de produits végétaux
EP3637030A1 (fr) * 2018-10-08 2020-04-15 Pfeifer Holz GmbH Procédé et installation de fabrication d'entretoises

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4753020A (en) * 1984-07-12 1988-06-28 Hilderbrand Holztechnik GmbH Dryer for wood
US5107602A (en) * 1988-07-15 1992-04-28 Loeoef Nils Oskar T Method and an apparatus for drying veneer and similar products
US5341580A (en) * 1993-01-22 1994-08-30 Teal William B Method for drying wood strands

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4753020A (en) * 1984-07-12 1988-06-28 Hilderbrand Holztechnik GmbH Dryer for wood
US5107602A (en) * 1988-07-15 1992-04-28 Loeoef Nils Oskar T Method and an apparatus for drying veneer and similar products
US5341580A (en) * 1993-01-22 1994-08-30 Teal William B Method for drying wood strands

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2511807C2 (ru) * 2012-06-06 2014-04-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Воронежский государственный университет инженерных технологий" (ФГБОУ ВПО "ВГУИТ") Сушилка для сыпучих материалов
EP2940414A1 (fr) * 2014-04-29 2015-11-04 ESG Kräuter GmbH Procédé et dispositif de séchage de produits végétaux
WO2015165585A1 (fr) * 2014-04-29 2015-11-05 Stg Dreihundertachtzigste Vermögensverwaltungs- Und Beteiligungsgesellschaft Mbh Procédé et dispositif de séchage de produits végétaux
EP2940414B1 (fr) 2014-04-29 2017-11-01 ESG Kräuter GmbH Procédé et dispositif de séchage de produits végétaux
EP3637030A1 (fr) * 2018-10-08 2020-04-15 Pfeifer Holz GmbH Procédé et installation de fabrication d'entretoises

Also Published As

Publication number Publication date
WO1996007070A3 (fr) 1996-04-11
AU3626695A (en) 1996-03-22

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