US3630456A - Method of manufacturing fiberboard - Google Patents

Method of manufacturing fiberboard Download PDF

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Publication number
US3630456A
US3630456A US826994A US3630456DA US3630456A US 3630456 A US3630456 A US 3630456A US 826994 A US826994 A US 826994A US 3630456D A US3630456D A US 3630456DA US 3630456 A US3630456 A US 3630456A
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gases
pipe
fluid
oxygen
gas
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US826994A
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Andre Mark
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N1/00—Pretreatment of moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/08—Moulding or pressing
    • B27N3/10—Moulding of mats
    • B27N3/14—Distributing or orienting the particles or fibres

Definitions

  • a relatively dry, oxygen-poor, heated fluid is provided for conveying wood fibers through the drying cycle subsequent to crushing the wood chips and for also conveying and distributing the wood fibers from the drying cycle onto a mat-forming wire.
  • the primary source of the fluid is the combustion gases from a burner. Secondary fluids including ambient air, recirculated gases from the drying cycle and inert gases may be introduced to cool the fluid to the desired temperature and provide the fluid with the correct amounts of oxygen and water vapor. ln reducing the temperature of the fluid, heat may be extracted by suitable heat exchanges and utilized for auxiliary purposes.
  • the gases used in the proces are maintained below 350 C., the oxygen content of the gases is maintained below 17 percent and the water vapor content of the gases is maintained below 100 grams per kilogram of dry gases.
  • a pneumatic conveyor to carry the dried fibers to a scattering device; the latter spreads them on a forming wire so as to make up the mattress which is ultimately compressed by heating plates.
  • the source of heat most generally used for drying consists of a chamber containing burners of liquid or gas fuel.
  • the combustion gases are diluted with atmospheric air so as to have a temperature of 250 C. at the inlet of the drier; but even at this temperature it can happen that particles ignite.
  • safety devices have been installed to inject a suitable extinguishing fluid into the pneumatic circulating system of drying, conveying, and scattering the fibers; these devices are controlled by supersensitive detectors reacting to temperature increases or sudden increases of pressure.
  • every hazard of inflammability or explosion is radically avoided in an installation for making fiber boards by the dry operating process, when these operations of crushing, drying, pneumatic conveyance and scattering the fibers on the forming wire are carried out in an oxygenpoor atmosphere of, for instance, less than 17 percent of said gas.
  • the system proposed by the invention is economical, because is does not require an exchanger between the burner chamber and the drier. It permits the recovery of calories by air condenser, exchange chamber of water vaporization, etc... Moreover, the system proposed by the invention has the further advantage to eliminate the risk of drying temperatures above 250 C. Raising the initial drying temperature to 280 C., even to 350C., permits to reduce the size of the drier and, consequently, to economize on installation costs.
  • the low oxygen content of the combustion gases discharged by the chamber of burners and providing the hot and dry gases required for drying the fibers is achieved by adding to them not only atmospheric cooling air, but also recirculated gases discharged by the drier.
  • the gases discharged by the drier or entering it are not circulated in the piping system which assures the pneumatic conveyance and the scattering of the fibers on the forming wire.
  • a second, substantially closed circulation is thus provided for the pneumatic conveyor
  • this second circulation cannot be entirely gastight, it will be supplied either continually or discontinually with a certain supplementary amount of hot gas from the drier circulation.
  • this supplementary gas can be derived directly from the burner chamber by means of interposing a cooling device of relatively low performance, since it is intended only as a supplementary output, of which, moreover, the calories can be recuperated.
  • this additional gas supply for the second circulating system can be provided by a source of inert gas, for example, nitrogen or carbonic gas.
  • FIG. 1 is a diagrammatic representation of that part of an installation for making wood-fiber boards which concerns the preparation of the fibers, showing the principles of the invention applied to it.
  • FIGS. 2 and 3 illustrate two variants regarding the cooling of the gas discharged by the drier and the use made of the waste heat thus recovered.
  • FIG. 4 is a diagram of that part of the equipment which concerns the forming of the fiber mattress.
  • FIG 5 is a detail section of the distribution chamber and the suction box of that part of the equipment.
  • FIG. 6 is a section along VI-VI.
  • FIG. 7 is a detail section showing one end of the axis of the compressing roller.
  • FIG. 8 is an end view of this axis.
  • FIG. 1 represents a crusher l, for example, a disk crusher, into which wood chips are introduced through an appropriate opening, taking care, however, to avoid communication with the surrounding atmosphere.
  • This crusher is connected by a pneumatic conveyance pipe 2 with a drier 3, in turn is connected by pipe 4 with a separator 5.
  • the latter has an air-lock 5a to isolate it from the surrounding air, a lower outlet 6 for dry fibers, and an upper outlet 7 for air practically free of the fibers it had to convey.
  • Pipe 7 leads to a suction fan 8, having an outlet 9 linked up with two pipes: a first one 10, leading a suitable outlet, and a second one 11, intended to assure the recirculation, as will be described hereunder.
  • Shutters l2 and I3, suitably coupled with one another, permit the adjustment of the relative proportions of drained and recirculated gas.
  • a combustion chamber 14 enclosing burners l5 and burning, for example, a liquid fuel.
  • an air inlet 16 adjustable by shutter 17.
  • the mixture of combustion gas and atmospheric air discharged by chamber 14 enters pipe l8, into which opens recirculating pipe 11. Further on this pipe 18 separates into pipe I9, leading into crusher l, and pipe 20, which communicates with outlet pipe 2 of the crusher, in this manner fonning a bypass; pipe 20 is regulated by shutter 21.
  • burners l5 and air entries 15a associated with them are regulated in such a way that they work within chamber 14 with an air excess of approximately 33 percent. Under these conditions, and if burners l5 burn a heavy fuel oil of average quality, the combustion gases will have a temperature of 800 C., with an approximate percentage of oxygen amountingto 14.3 percent. From pipe 16 a sufficient quantity of the surrounding air is added to reduce the temperature to approx. 560 C., which corresponds to an oxygen content of about 16.5 percent, i.e., less than the limit value of 17 percent, considered to involve a risk of inflammability or explosion.
  • This first or primary mixture contains about 16 g. of water vapor per kilogram of dry gas.
  • the temperature of the secondary mixture, arriving in this state into drier 3, will be reduced in it and in the rest of the circulation to return to 100 C. at the point where recirculating pipe joins outlet pipe 18 at chamber 14.
  • the oxygen content it is easy to realize that it remains a constant 16.5 percent, since the recirculated gas discharged by pipe 11 is of the same composition as the primary mixture discharged by chamber 14, except for its water vapor content.
  • the oxygen content of the secondary mixture is inferior to the limit amount considered hazardous, so that there is no longer a possibility for particles to ignite, whereby the initial cause of flash flames and explosions is eliminated.
  • the crusher is traversed, at least in part, by a gas mixture originating in pipe 18, with the effect that, even if local phenomena of overheating of any importance 9 would occur in the crusher, causing the thermic decomposition of fiber particles, they cannot provoke combustion in the proper sense.
  • crushers working under steam pressure could, of course, be utilized, which would automatically eliminate the risk of ignitions in the crusher. But evidently, in this case it would not be possible to circulate the secondary gas mixture in the crusher.
  • FIG. 1 proposes a reserve 22 of inert gas (e.g., a set of nitrogen bottles or of C0,), connected with pipe 11 by pipe 23, on which a shutter 24 is interposed; this'shutter is controlled by an oxygen detector 25 mounted on pipe II.
  • a reserve 22 of inert gas e.g., a set of nitrogen bottles or of C0,
  • this'shutter is controlled by an oxygen detector 25 mounted on pipe II.
  • the detecting device would open shutter 24, and the inert gas of source 22 would spread in the circulating system and eliminate the dangerous oxygen.
  • FIG. 2 differs from the one of FIG. 1 insofar as there is a temperature exchanger 26 interposed on pipe 9; here the calories still present in the gas circulating in this pipe are transferred to surrounding air taken in 27, to be discharged into pipe 28.
  • the air thus heated is conveyed through pipes 29 and 30, both equipped with shutters 31 and 32, into enclosures 33 and 34, representing, for instance, tunnels intended for the various treatments of the boards, such as preheating and conditioning. No details are provided for the construction of these enclosures, which could be of any appropriate type, connected or disconnected.
  • enclosure 33 is in direct contact, i.e., the air coming from its inlet pipe 29 circulates directly around the treated products 35, the air in enclosure 34 heats only the exterior walls of an inner tunnel, containing the products 36 to be treated, and it is equipped with its own circulating device. 1
  • FIG. 1 Another difference between the installations of FIG. 1 and FIG. 2 consists of the fact that from the discharge of pipe 28 a part of the heated air of exchanger 26 is taken and conducted through pipe 37 to fan 38, to feed the burners l5. Naturally, this additional heating of the combustive air permits to reduce the fuel quantity, while maintaining unchanged conditions in the combustion chamber. On the other hand, it is easy to realize that through the intervention of the temperature exchanger 26, the gases recuperated by pipe 11 are colder than in the case of FIG. 1.
  • Pipe 26 a indicates the drain for condensed water recovered from the gases circulating in pipe 9, due to their cooling.
  • FIG. 2 It is clear that by comparison with FIG. 1 the installation of FIG. 2 has the advantage that the gas recovered by pipe 11 carries a distinctly lower quantity of water vapor; this fact increases the drying potential of the secondary mixture circulating in pipe 18. Moreover, a recuperation of calories is achieved which might be of considerable interest in certain cases, since it results in a decrease of fuel consumption per ton of finished product.
  • heat recovery and moisture condensation are effected exclusively for the gas introduced into recirculating pipe 11, on which, for this purpose, a chamber 39 is interposed; here cold water'is vaporized which arrives from pipe 40.
  • This water is received by a pump 41 and conveyed into an air heater 42, associated with a chamber or tunnel 43.
  • a draining pump for the used water is indicated by 44.
  • a part of the hot water delivery of pump 41 passes through pipe 45 which opens into an exchanger 46, representing a device for a preheating combustive air for burners 15. It is a matter of course that in this case again the air carried by pipe 11 into pipe 18 will be markedly colder, just as in the equipment of FIG. 2.
  • FIGS. 2 and 3 are perfectly interchangeable, both with regard to the kind of apparatus and-their disposition within the installation.
  • the circulation system conveying the oxygen-poor gas mixture concerns only the crusher and the drier of the machinery for making fiber boards. It does not affect the conveyance system carrying dry fibers to the forming wire apparatus nor the apparatus itself.
  • the fonning apparatus could also be included in the circulations of FIGS. 1, 2, and 3, but in practice this would entail complications better to be avoided. Therefore, it is preferable to equip the fonning apparatus with a second circulating system, more or less independent of the first one.
  • FIG. 4 shows an apparatus 47 discharging 12 fibers, suitably connected with the outlet of separator 5 of FIGS. l-3.
  • Apparatus 47 discharges dry fibers into a hopper 48, which conveys them to the suction of a fan 49 through an air-lock 49a isolating it from the surrounding air. From here the fibers are carried pneumatically through pipe 50, opening into difiuser S1 of a distribution box 52.
  • the latter covers a forming wire 53 made of wire gauze, which circulates along the perforated upper surface 54 of a suction box 55.
  • the fibers settle on the wire carpet 53 to constitute the mattress 56, while the conveyance gas penetrates into box 55; the latter is connected by pipe 55a with the suction of fan 57.
  • pipe 18 of FIG. 1 to 3 by means of an intake 61, equipped with a regulating shutter 62.
  • Pipe 61 passes through an exchanger 63, where the gas mixture transfers calories to water coming in through pipe 64 and leaving, heated, through pipe 65; this hot water could be used, for instance, to enter a broiler producing the steam required for boiling the wood chips before they are crushed.
  • the cooled gas mixture is conducted by'pipe 66 into pipe 60 described above, i.e., to the suction of fan 49.
  • pipe 61 is branched up with pipe 18 above the junction point of the latter with. recirculating pipe 11; this for the purpose of feeding the circulation with an oxygen-poor gas, namely approximately 14.3 percent in the given example, thus taking eventual air reentries into account.
  • a gas detector 67 for the oxygen proportion is inserted in the circulation system (on pipe 50 in the example); this detector controls a regulating shutter 68 on pipe 61.
  • the supplementary gas mixture is supplied to the circulating system according to its needs.
  • detector 67 can also command a shutter 69, mounted on pipe 70, which connects a source of inert gas 71 with pipe 66, i.e., with fan 49. If a considerable discharge can be had from source 71, the latter could supply the needed addition instead of pipe 61, which then would normally be kept closed. But as shown, it is also possible to use the two arrangements simultaneously (i.e., shutters 68 and 69).
  • detector 67 control only shutter 68 in normal conditions, but in cases where, shutter 68 being entirely open, the oxygen proportion would continue to rise, detector 67 would open shutter, 69, in order to introduce a sufficient quantity of inert gas into the pipe system and eliminate any risk of inflammation or explosion.
  • a roller 72 pressing onto mattress 56, is placed at the exit opening of distribution box or forming chamber 52.
  • Detail diagram FIG. 5 shows more clearly that this roller flattens the mattress as it leaves the forming chamber in order to assure a relative airtightness between the distribution box and the atmosphere; this does not result in any disadvantage, as the mattress in question will be subjected anyway to the action of compressing cylinders before reaching the heating plate press.
  • a flap 73 bearing against the roller and sealing the space between its outer surface and the wall, is attached at the upper edge of the opening provided in the box for placing the roller.
  • FIG. 5 shows more clearly that this roller flattens the mattress as it leaves the forming chamber in order to assure a relative airtightness between the distribution box and the atmosphere; this does not result in any disadvantage, as the mattress in question will be subjected anyway to the action of compressing cylinders before reaching the heating plate press.
  • the bearing blocks 74 supporting shaft 75 of the roller are slidably mounted in guides 76 (FIG. 7), integral with the walls; the blocks 74 can be adjusted by means of threaded stems 77 (FIGS. 6 and 8) and nuts 78. Lids 79 (FIG. 6) cover these mechanisms to ensure tightness. If wanted, shaft 75 can be made projecting through a flexible wall 80, to carry a suitable driving pinion 81.
  • Cover flaps 82 are attached between the walls of box 52 and the forming wire mat 53, at the sides and towards the entrance of the wire gauze, in order to limit air reentry from without or gas leaks from within.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Wood Science & Technology (AREA)
  • Forests & Forestry (AREA)
  • Drying Of Solid Materials (AREA)
US826994A 1968-05-22 1969-05-22 Method of manufacturing fiberboard Expired - Lifetime US3630456A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3906064A (en) * 1973-02-12 1975-09-16 Little Inc A Process for dry forming paper
US4045531A (en) * 1974-06-28 1977-08-30 Bison-Werke Bahre & Greten Gmbh & Co. Kg Process for the production of chipboards and the like
US5989465A (en) * 1997-04-30 1999-11-23 Sunds Defibrator Industries Ab Method of manufacturing a board
US20070295438A1 (en) * 2004-11-10 2007-12-27 Fritz Schneider Method And Device To Prevent Contamination Of A Transport Device By Freshly Glued Fibers
CN105195293A (zh) * 2015-10-22 2015-12-30 山东冠峰机械股份有限公司 一种物料破碎方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2845080C2 (de) * 1978-10-17 1981-10-08 Casimir Kast Gmbh & Co Kg, 7562 Gernsbach Vorrichtung zum Beheizen eines Vlieses

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1277333A (en) * 1918-01-26 1918-08-27 Edgar T Meakin Non-skidding device.
US2757115A (en) * 1953-01-30 1956-07-31 Weyerhaeuser Timber Co Felted, lignocellulose products and method of making the same
US2989348A (en) * 1959-12-01 1961-06-20 George G Reed Fire eliminator for air conveying systems
US3371137A (en) * 1968-02-27 Defibrator Ab Method in the manufacture of fiber board

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3371137A (en) * 1968-02-27 Defibrator Ab Method in the manufacture of fiber board
US1277333A (en) * 1918-01-26 1918-08-27 Edgar T Meakin Non-skidding device.
US2757115A (en) * 1953-01-30 1956-07-31 Weyerhaeuser Timber Co Felted, lignocellulose products and method of making the same
US2989348A (en) * 1959-12-01 1961-06-20 George G Reed Fire eliminator for air conveying systems

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Dust Explosions by David J. Price, Chemical and Metallurgical Engineering, Vol. 24, No. 11, March 16, 1921, pages 4, 5 and 6. *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3906064A (en) * 1973-02-12 1975-09-16 Little Inc A Process for dry forming paper
US4045531A (en) * 1974-06-28 1977-08-30 Bison-Werke Bahre & Greten Gmbh & Co. Kg Process for the production of chipboards and the like
US5989465A (en) * 1997-04-30 1999-11-23 Sunds Defibrator Industries Ab Method of manufacturing a board
US20070295438A1 (en) * 2004-11-10 2007-12-27 Fritz Schneider Method And Device To Prevent Contamination Of A Transport Device By Freshly Glued Fibers
US8052354B2 (en) * 2004-11-10 2011-11-08 Dieffenbacher GmbH Maschinen-und Anlagenbau Method and device to prevent contamination of a transport device by freshly glued fibers
CN105195293A (zh) * 2015-10-22 2015-12-30 山东冠峰机械股份有限公司 一种物料破碎方法

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DE1926216A1 (de) 1969-11-27
FR1591581A (de) 1970-05-04

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