EP0170648A1 - Process for drying delicate products, e.g. wood - Google Patents

Process for drying delicate products, e.g. wood Download PDF

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Publication number
EP0170648A1
EP0170648A1 EP19850890167 EP85890167A EP0170648A1 EP 0170648 A1 EP0170648 A1 EP 0170648A1 EP 19850890167 EP19850890167 EP 19850890167 EP 85890167 A EP85890167 A EP 85890167A EP 0170648 A1 EP0170648 A1 EP 0170648A1
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Prior art keywords
drying
dried
air
temperature
condensation
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EP19850890167
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German (de)
French (fr)
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EP0170648B1 (en
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Josef Leisser
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/06—Controlling, e.g. regulating, parameters of gas supply
    • F26B21/08—Humidity
    • F26B21/086—Humidity by condensing the moisture in the drying medium, which may be recycled, e.g. using a heat pump cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
    • F26B3/04—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour circulating over or surrounding the materials or objects to be dried

Definitions

  • the invention relates to a method for drying sensitive goods, e.g. Wood in which the material to be dried is heated in a drying chamber and dried by circulating drying air from which the moisture is removed by condensation drying.
  • sensitive goods e.g. Wood
  • the material to be dried is heated in a drying chamber and dried by circulating drying air from which the moisture is removed by condensation drying.
  • the drying air is heated to the drying temperature, after which this air is circulated in the drying chamber until the drying air is enriched with moisture; this moisture is then deposited on a cooled surface by condensation.
  • moisture is supplied to the drying air in a controlled manner in order to be able to use high drying temperatures without damaging the material to be dried.
  • the moisture extracted from the material to be dried is also separated out by condensation on cooled surfaces.
  • a drying process is known in which the drying air is kept at a constant, low temperature and is dried by a dehumidifier.
  • the goods are dried at a temperature of around 30 ° C, with the moisture content of the drying air being controlled accordingly so as not to fall below a lower limit value, since otherwise the surface may become clogged.
  • the temperature of the material to be dried is essentially the same as the temperature of the drying air.
  • the invention has for its object a method to create the type mentioned in which the material to be dried can be dried quickly and gently at high temperatures.
  • this object is achieved in that the material to be dried is heated to the drying temperature, then the temperature of the drying air is reduced below that of the material to be dried, after which condensation drying of the drying air is then started. It is thereby achieved that the outer layers of the material to be dried are always cooler than the inner layers, as a result of which an increase in the relative humidity of the material to be dried occurs to the outside, thereby avoiding cracking of the outer layers, the "formwork" of the wood. As a result, the relative air humidity of the drying air can be kept lower, since the material to be dried itself contains the necessary moisture on the outer layer, as a result of which a faster drying process is achieved. In addition, the lower relative humidity of the drying air prevents the surface of the material to be stained.
  • the temperature of the drying air can be reduced by controlled supply of cool fresh air, which enables the temperature to be reduced without the use of energy.
  • the temperature of the drying air can be reduced to a value which is approximately 5 - 10 ° C below the temperature of the material to be dried, whereby a particularly effective temperature gradient is achieved.
  • the latter can be left to act on the material to be dried without condensation drying until the relative humidity of the drying air has risen to approximately 90-95%, after which the drying air is then condensed to be dried, in particular by passing it on cool condensation surfaces until the relative air humidity has dropped to about 50-60%, whereupon the condensation drying is interrupted until the relative air humidity of the drying air has risen again to about 90-95%, after which the condensation drying is started again what cycles until the desired degree of drying of the material to be dried is repeated.
  • This intermittent mode of operation allows the fans for the air circulation to be switched off with moisture during the enrichment phase of the drying air, which results in the desired energy saving.
  • the material to be dried can be returned to the initial temperature, e.g. 80 ° C, heated and the drying process is repeated until the material to be dried has the desired moisture content, whereby the drying is always kept in the desired range of moisture release.
  • the drying chamber 1 has well-insulated walls 2 provided with a vapor barrier. Air circulation channels 4 are left free in the wood stack 3. Air circulation channels 5 are provided above the wood stack 3, with which the drying air is guided to the back of the wood stack 3 facing away from the fans 6. 6 heating registers 7 and a cooling register 8 are arranged in front of the fans in the flow direction of the drying air. Below the cooling register 8, a condensate collecting channel 9 and a condensate drain 10 connected to it are provided. The cooling register 8 can be supplied with cool fresh air via fans 11. The cooling register 8 has channels 12 to which fresh air can be applied and channels 13 through which the drying air flows and separated from the channels 12. A hygrometer and a thermal sensor for controlling the fans and registers are also not shown in the chamber
  • the fans 6 are arranged below the ceiling on the upper edge of the front of the stack, the number being chosen so that a corresponding air flow is achieved over the entire width of the chamber.
  • the heating register 7 are also distributed over the chamber width. Also the cooling coil extends over the entire width of the chamber, a uniform conditioning of the TOTAL - to achieve th drying air flow.
  • the wood stacking depth should not exceed 2.50 m, since otherwise the air's willingness to absorb water from the wood would be different in the front and rear stacking areas and color errors or cracks could occur.
  • the chamber can be loaded using a forklift or trolley.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Microbiology (AREA)
  • Drying Of Solid Materials (AREA)

Abstract

1. Process for drying delicate products, e.g. wood, in which the product to be dried is warmed in a drying chamber and is dried by the circulation of drying air from which the moisture is removed by condensation drying, characterized in that the product to be dried is heated to the drying temperature and subsequently the temperature of the drying air is reduced, that the reduction of the temperature is to a value which is below the temperature of the product to be dried, whereafter the actual drying process is begun in which the drying air is dehumidified by condensation drying and subsequently moisture is withdrawn from the product, alternately.

Description

Die Erfindung bezieht sich auf ein Verfahren zur Trocknung von empfindlichen Gütern, z.B. Holz, bei welchem das zu trocknende Gut in einer Trocknungskammer erwärmt und durch Umwälzung von Trocknungsluft, der die Feuchtigkeit durch Kondensationstrocknung entzogen wird, getrocknet wird.The invention relates to a method for drying sensitive goods, e.g. Wood in which the material to be dried is heated in a drying chamber and dried by circulating drying air from which the moisture is removed by condensation drying.

Bei einem bekannten Verfahren dieser Art wird die Trocknungsluft auf die Trocknungstemperatur erhitzt, wonach dann diese Luft so lange in der Trocknungskammer umgewälzt wird, bis die Trocknungsluft mit Feuchtigkeit angereichert ist; diese Feuchtigkeit wird dann an einer gekühlten Fläche durch Kondensation abgeschieden.In a known method of this type, the drying air is heated to the drying temperature, after which this air is circulated in the drying chamber until the drying air is enriched with moisture; this moisture is then deposited on a cooled surface by condensation.

Bei einem anderen bekannten Verfahren dieser Art wird der Trocknungsluft gesteuert Feuchtigkeit zugeführt, um hohe Trocknungstemperaturen ohne Schädigung des Trocknungsgutes einsetzen zu können. Die dem Trocknungsgut entzogene Feuchtigkeit wird ebenfalls durch Kondensation an gekühlten Flächen abgeschieden.In another known method of this type, moisture is supplied to the drying air in a controlled manner in order to be able to use high drying temperatures without damaging the material to be dried. The moisture extracted from the material to be dried is also separated out by condensation on cooled surfaces.

Aus der DE-AS 24 57 654 ist ein Trocknungsverfahren bekannt, bei dem die Trocknungsluft auf konstanter, niedriger Temperatur gehalten und über einen Entfeuchter getrocknet wird. Dabei wird die Trocknung des Gutes bei einer Temperatur von etwa 30°C vorgenommen, wobei der Feuchtigkeitsgehalt der Trocknungsluft entsprechend gesteuert wird, um einen unteren Grenzwert nicht zu unterschreiten, da es sonst zu einer Verschalung der Oberfläche kommen kann. Dabei ist die Temperatur des zu trocknenden Gutes im wesentlichen gleich der Temperatur der Trocknungsluft. Mit dem bekannten Verfahren ist zwar eine schonende Trocknung des Gutes erreichbar, jedoch ist dieses Verfahren im Hinblick auf die Dauer des Trocknungsvorganges unwirtschaftlich, wobei insbesondere für die Trocknung von dicken Stücken eine entsprechende Zeit notwendig ist, um die Feuchtigkeit aus dem Mittelbereich des Trocknungsgutes zu entfernen.From DE-AS 24 57 654 a drying process is known in which the drying air is kept at a constant, low temperature and is dried by a dehumidifier. The goods are dried at a temperature of around 30 ° C, with the moisture content of the drying air being controlled accordingly so as not to fall below a lower limit value, since otherwise the surface may become clogged. The temperature of the material to be dried is essentially the same as the temperature of the drying air. With the known method, gentle drying of the material can be achieved, but this method is uneconomical with regard to the duration of the drying process, with a corresponding time being necessary in particular for the drying of thick pieces in order to remove the moisture from the central region of the material to be dried .

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren der eingangs genannten Art zu schaffen, bei welchem das Trocknungsgut rasch und schonend bei hohen Temperaturen getrocknet werden kann.The invention has for its object a method to create the type mentioned in which the material to be dried can be dried quickly and gently at high temperatures.

Erfindungsgemäß wird diese Aufgabe dadurch gelöst, daß das Trocknungsgut auf die Trocknungstemperatur aufgeheizt wird, anschließend die Temperatur der Trocknungsluft unter jene des Trocknungsgutes abgesenkt wird, wonach dann mit der Kondensationstrocknung der Trocknungsluft begonnen wird. Dadurch wird erreicht, daß die äußeren Schichten des Trocknungsgutes immer kühler sind als die inneren Schichten, wodurch ein Anstieg der relativen Feuchtigkeit des Trocknungsgutes nach außen hin auftritt, wodurch ein Rissigwerden der Außenschichten, die "Verschalung" des Holzes, vermieden ist. Dadurch kann die relative Luftfeuchtigkeit der Trocknungsluft niedriger gehalten werden, da eben das Trocknungsgut selbst die nötige Feuchtigkeit an der Außenschicht enthält, wodurch ein rascherer Trocknungsvorgang erreicht ist. Überdies wird durch die niedrigere relative Feuchtigkeit der Trocknungsluft ein Fleckigwerden der Oberfläche des Trocknungsgutes verhindert.According to the invention, this object is achieved in that the material to be dried is heated to the drying temperature, then the temperature of the drying air is reduced below that of the material to be dried, after which condensation drying of the drying air is then started. It is thereby achieved that the outer layers of the material to be dried are always cooler than the inner layers, as a result of which an increase in the relative humidity of the material to be dried occurs to the outside, thereby avoiding cracking of the outer layers, the "formwork" of the wood. As a result, the relative air humidity of the drying air can be kept lower, since the material to be dried itself contains the necessary moisture on the outer layer, as a result of which a faster drying process is achieved. In addition, the lower relative humidity of the drying air prevents the surface of the material to be stained.

Vorteilhafterweise kann die Temperatur der Trocknungsluft durch gesteuerte Zufuhr von kühler Frischluft abgesenkt werden, wodurch die Temperaturabsenkung ohne Energieaufwand ermöglicht ist.Dabei kann die Temperatur der Trocknungsluft auf einen Wert abgesenkt werden, der etwa 5 - 10°C unter jenem der Temperatur des Trocknungsgutes liegt, wodurch ein besonders wirksames Temperaturgefälle erzielt ist. Für eine besonders hohe Energieeinsparung kann nach Erreichen der gewünschten Temperatur der Trocknungsluft letztere so lange ohne Kondensationstrocknung auf das Trocknungsgut einwirken gelassen werden, bis die relative Luftfeuchtigkeit der Trocknungsluft auf etwa 90 - 95% gestiegen ist, wonach dann die Kondensationstrocknung der Trocknungsluft, insbesondere durch Vorbeiführen an kühlen Kondensationsflächen, vorgenommen wird, bis die relative Luftfeuchtigkeit auf etwa 50 - 60 % abgesunken ist, worauf dann die Kondensationstrocknung unterbrochen wird, bis die relative Luftfeuchtigkeit der Trocknungsluft wieder auf etwa 90 - 95 % gestiegen ist, wonach dann erneut die Kondensationstrocknung aufgenommen wird, welche Zyklen bis zum Erreichen des gewünschten Trocknungsgrades des Trocknungsgutes wiederholt werden.Advantageously, the temperature of the drying air can be reduced by controlled supply of cool fresh air, which enables the temperature to be reduced without the use of energy. The temperature of the drying air can be reduced to a value which is approximately 5 - 10 ° C below the temperature of the material to be dried, whereby a particularly effective temperature gradient is achieved. For particularly high energy savings, once the desired temperature of the drying air has been reached, the latter can be left to act on the material to be dried without condensation drying until the relative humidity of the drying air has risen to approximately 90-95%, after which the drying air is then condensed to be dried, in particular by passing it on cool condensation surfaces until the relative air humidity has dropped to about 50-60%, whereupon the condensation drying is interrupted until the relative air humidity of the drying air has risen again to about 90-95%, after which the condensation drying is started again what cycles until the desired degree of drying of the material to be dried is repeated.

Durch diese intermittierende Arbeitsweise können die Ventilatoren für die Luftumwälzung während der Anreicherungsphase der Trocknungsluft mit Feuchtigkeit abgestellt werden, was die gewünschte Energieeinsparung ergibt. Dabei kann nach dem durch die Kondensationstrocknung hervorgerufenen Absenken der Temperatur des Trocknungsgutes unter einen vorgewählten Wert das Trocknungsgut wieder auf die Ausgangstemperatur, z.B. 80°C, erwärmt und der Trocknungsvorgang so lange wiederholt werden, bis das Trocknungsgut den gewünschten Feuchtigkeitsgehalt aufweist, wodurch die Trocknung immer in dem gewünschten Bereich der Feuchtigkeitsabgabe gehalten wird.This intermittent mode of operation allows the fans for the air circulation to be switched off with moisture during the enrichment phase of the drying air, which results in the desired energy saving. After the condensation drying has caused the temperature of the material to be dried to drop below a preselected value, the material to be dried can be returned to the initial temperature, e.g. 80 ° C, heated and the drying process is repeated until the material to be dried has the desired moisture content, whereby the drying is always kept in the desired range of moisture release.

In der Zeichnung ist ein Ausführungsbeispiel einer zur Durchführung des erfindungsgemäßen Verfahrens ausgebildeten, für die Holztrocknung geeigneten Trocknungskammer dargestellt; es zeigen:

  • Fig. 1 einen Vertikalschnitt durch die mit Trocknungsgut beschickte Trocknungskammer, und
  • Fig. 2 schaubildlich das für die Kondensationstrocknung vorgesehene Kühlregister.
The drawing shows an exemplary embodiment of a drying chamber designed for carrying out the method according to the invention and suitable for drying wood; show it:
  • Fig. 1 is a vertical section through the drying chamber loaded with drying material, and
  • Fig. 2 shows the cooling register provided for the condensation drying.

Die Trocknungskammer 1 weist gut isolierte, mit einer Dampfsperre versehene Wandungen 2 auf. Im Holzstapel 3 sind Luftumwälzkanäle 4 freigelassen. Oberhalb des Holzstapels 3 sind Luftumwälzkanäle 5 vorgesehen, mit welchen die Trocknungsluft an die den Ventilatoren 6 abgekehrte Rückseite des Holzstapels 3 geführt wird. In Strömungsrichtung der Trocknungsluft sind vor den Ventilatoren 6 Heizregister 7 und ein Kühlregister 8 angeordnet. Unterhalb des Kühlregisters 8 ist eine Kondenswasserauffangrinne 9 und eine mit dieser verbundene Kondenswasserableitung 10 vorgesehen. Das Kühlregister 8 ist über Ventilatoren 11 mit kühler Frischluft beaufschlagbar. Das Kühlregister 8 weist dabei mit Frischluft beaufschlagbare Kanäle 12 und von der Trocknungsluft durchströmte, von den Kanälen 12 getrennte Kanäle 13 auf. In der Kammer sind außerdem nicht dargestellt noch ein Hygrometer und ein Thermofühler für die Steuerung der Uentilatoren und RegisterThe drying chamber 1 has well-insulated walls 2 provided with a vapor barrier. Air circulation channels 4 are left free in the wood stack 3. Air circulation channels 5 are provided above the wood stack 3, with which the drying air is guided to the back of the wood stack 3 facing away from the fans 6. 6 heating registers 7 and a cooling register 8 are arranged in front of the fans in the flow direction of the drying air. Below the cooling register 8, a condensate collecting channel 9 and a condensate drain 10 connected to it are provided. The cooling register 8 can be supplied with cool fresh air via fans 11. The cooling register 8 has channels 12 to which fresh air can be applied and channels 13 through which the drying air flows and separated from the channels 12. A hygrometer and a thermal sensor for controlling the fans and registers are also not shown in the chamber

vorgesehen. Die Ventilatoren 6 sind unterhalb der Decke an der Oberkante der Stapelvorderseite angeordnet, wobei die Zahl so gewählt ist, daß über die gesamte Kammerbreite eine entsprechende Luftströmung erzielt ist. Die Heizregister 7 sind dabei ebenfalls über die Kammerbreite verteilt. Auch das Kühlregister erstreckt sich über die gesamte Kammerbreite, um eine gleichmäßige Konditionierung des gesam- ten Trocknungsluftstromes zu erreichen.intended. The fans 6 are arranged below the ceiling on the upper edge of the front of the stack, the number being chosen so that a corresponding air flow is achieved over the entire width of the chamber. The heating register 7 are also distributed over the chamber width. Also the cooling coil extends over the entire width of the chamber, a uniform conditioning of the TOTAL - to achieve th drying air flow.

Die Holzstapeltiefe sollte 2,50 m nicht überschreiten, da sonst die Wasseraufnahmebereitschaft der Luft vom Holz her im vorderen und hinteren Stapelbereich unterschiedlich wäre und dadurch Farbfehler oder Risse auftreten könnten.The wood stacking depth should not exceed 2.50 m, since otherwise the air's willingness to absorb water from the wood would be different in the front and rear stacking areas and color errors or cracks could occur.

Im allgemeinen kann die Kammer, wie auch bei anderen Trocknungsanlagen, mittels Stapler oder Rollwagen beschickt werden. Es ist jedoch darauf zu achten, daß zwischen Holzstapel und Rückwand genügend Abstand bleibt, um eine gute Luftzirkulation zu ermöglichen. Ebenso verhält es sich bei der Höhe, wobei die Stapelobergrenze durch die Ventilatorunterkante oder Zwischendecke begrenzt ist.In general, as with other drying systems, the chamber can be loaded using a forklift or trolley. However, it is important to ensure that there is sufficient clearance between the wood stack and the rear wall to allow good air circulation. The same applies to the height, with the upper stack limit being limited by the lower edge of the fan or false ceiling.

Bei Betrieb der Vorrichtung wird folgendermaßen vorgegangen:

  • Sobald die Kammer 1 mit Holz beschickt ist, wird diese luftdicht verschlossen und rasch bis zu einer gewünschten Temperatur, z.B. 80°C aufgeheizt. Ist diese Temperatur erreicht, d.h. bis ins Holzinnere vorgedrungen, schaltet sich das Heizregister 7, gesteuert durch den Thermostat, ab. Die Ventilatoren 6 für die Trocknungsluftumwälzung in der Kammer laufen weiter, und es wird gleichzeitig der Frischluftkreis eingeschaltet und somit die Kammertemperatur um einiges gesenkt. Ist dies (ca. 5 - 10°C) erreicht, schaltet sich auch der Kühlkreis aus, und der eigentliche Trocknungsprozeß beginnt. Da die Holztemperatur höher ist als die Raumtemperatur, verlagert sich das Wasser rasch vom Holzinneren an die Holzoberfläche. Nun ist es notwendig, Luftumwälzung und Kühlung in kurzen Zeitabständen, intervallweise zu steuern.
  • a) Während der Laufzeit von Luftumwälzung und Kühlung wird das Wasser von der Holzoberfläche an die Luft abgegeben und am Kühlregister 8 ausgeschieden. Dieser Vorgang erfolgt solange, bis die Luftfeuchtigkeit in der Kammer auf 50 - 60% gesunken ist.
  • b) Während der Stehzeit von Luftumwälzung und Kühlung bleibt das Wasser an der Holzoberfläche und verhindert somit eine Verschalung oder Rißbildung. Die Stehzeit dauert solange, bis sich die Luft im Stapel wieder auf ca. 90-95% angereichert hat.
The device is operated as follows:
  • As soon as the chamber 1 is loaded with wood, it is sealed airtight and quickly heated to a desired temperature, for example 80 ° C. When this temperature has been reached, that is to say penetrated into the interior of the wood, the heating register 7 switches off, controlled by the thermostat. The fans 6 for the drying air circulation in the chamber continue to run, and at the same time the fresh air circuit is switched on and the chamber temperature is thus reduced considerably. When this is reached (approx. 5 - 10 ° C), the cooling circuit also switches off and the actual drying process begins. Since the wood temperature is higher than the room temperature, the water quickly shifts from the inside of the wood to the wood surface. Now it is necessary to control air circulation and cooling at short intervals, at intervals.
  • a) During the period of air circulation and cooling, the water is released from the wood surface into the air and excreted at the cooling register 8. This process continues until the air humidity in the chamber has dropped to 50-60%.
  • b) During the standing time of air circulation and cooling, the water remains on the wood surface and thus prevents shuttering or cracking. The standing time lasts until the air in the stack has again enriched to approx. 90-95%.

Während dieser Intervallvorgänge kühlt sich das Holz jedoch immer weiter ab; daher ist es notwendig, bei einer Holztemperatur von beispielsweise 60°C den Holzstapel 3 wieder mittels des Heizregisters7auf 80° oder noch höher aufzuheizen und den ganzen Vorgang so lange zu wiederholen, bis man das Holz auf die gewünschte Holzfeuchtigkeit getrocknet hat.During these interval processes, however, the wood continues to cool down; It is therefore necessary, at a wood temperature of, for example, 60 ° C, to heat the wood stack 3 again to 80 ° or even higher by means of the heating register 7 and to repeat the whole process until the wood has dried to the desired wood moisture.

Die Vorteile des erfindungsgemäßen Verfahrens sind somit:

  • 1. geringer Stromverbrauch, da die Ventilatoren länger stehen als laufen;
  • 2. umweltfreundlich, da keine etwa entstehenden säurehältigen Dämpfe ins Freie abgegeben werden;
  • 3. schnellere Trocknung als bei allen herkömmlichen Anlagen;
  • 4. Energierückgewinnung in hohem Maße ohne Kostenaufwand möglich;
  • 5. die Trocknungsqualität ist beim erfindungsgemäßen Verfahren besser als bei herkömmlichen Trockenanlagen und auch besser als beim Lufttrocknen;
  • 6. die Trocknungskosten liegen niedriger als beim Lufttrocknen.
The advantages of the method according to the invention are therefore:
  • 1. low power consumption because the fans are standing longer than running;
  • 2. Environmentally friendly, since no acidic vapors are released into the open;
  • 3. faster drying than with all conventional systems;
  • 4. Energy recovery is possible to a high degree without cost;
  • 5. The drying quality in the method according to the invention is better than in conventional drying plants and also better than in air drying;
  • 6. The drying costs are lower than for air drying.

Claims (5)

1. Verfahren zur Trocknung von empfindlichen Gütern, z.B. Holz, bei welchem das zu trocknende Gut in einer Trocknungskammer erwärmt und durch Umwälzen von Trocknungsluft, der die Feuchtigkeit durch Kondensationstrocknung entzogen wird, getrocknet wird, dadurch gekennzeichnet, daß das Trocknungsgut auf die Trocknungstemperatur aufgeheizt wird, anschließend die Temperatur der Trocknungsluft unter jene des Trocknungsgutes abgesenkt wird, wonach dann mit der Kondensationstrocknung der Trocknungsluft begonnen wird.1. Process for drying sensitive goods, e.g. Wood in which the material to be dried is heated in a drying chamber and dried by circulating drying air from which the moisture is removed by condensation drying, characterized in that the material to be dried is heated to the drying temperature, then the temperature of the drying air is below that of the material to be dried is lowered, after which condensation drying of the drying air is then started. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Temperatur der Trocknungsluft durch gesteuerte Zufuhr von kühler Frischluft abgesenkt wird.2. The method according to claim 1, characterized in that the temperature of the drying air is lowered by controlled supply of cool fresh air. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Temperatur der Trocknungsluft auf einen Wert abgesenkt wird, der etwa 5 - 10°C unter jenem der Temperatur des Trocknungsgutes liegt.3. The method according to claim 1 or 2, characterized in that the temperature of the drying air is reduced to a value which is about 5 - 10 ° C below that of the temperature of the material to be dried. 4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß nach Erreichen der gewünschten Temperatur der Trocknungsluft letztere so lange ohne Kondensationstrocknung auf das Trocknungsgut einwirken gelassen wird, bis die relative Luftfeuchtigkeit der Trocknungsluft auf etwa 90 - 95 1 gestiegen ist, wonach dann die Kondensationstrocknung der Trocknungsluft, insbesonders durch Vorbeiführen an kühlen Kondensationsflächen, vorgenommen wird, bis die relative Luftfeuchtigkeit auf etwa 50 - 60 % abgesunken ist, worauf dann die Kondensationstrocknung unterbrochen wird, bis die relative Luftfeuchtigkeit der Trocknungsluft wieder auf etwa 90 - 95 gestiegen ist, wonach dann erneut die Kondensationstrocknung aufgenommen wird, welche Zyklen bis zum Erreichen des gewünschten Trocknungsgrades des Trocknungsgutes wiederholt werden.4. The method according to any one of claims 1 to 3, characterized in that after reaching the desired temperature of the drying air, the latter is allowed to act on the material to be dried without condensation drying until the relative humidity of the drying air has risen to approximately 90-95 1, after which then the condensation drying of the drying air is carried out, in particular by passing cool condensation surfaces, until the relative air humidity has dropped to about 50-60%, whereupon the condensation drying is interrupted until the relative air humidity of the drying air has risen again to about 90-95 Then the condensation drying is started again, which cycles are repeated until the desired degree of drying of the material to be dried is reached. 5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß nach dem durch die Kondensationstrocknung hervorgerufenen Absenken der Temperatur des Trocknungsgutes unter einen vorgewählten Wert das Trocknungsgut wieder auf die Ausgangstemperatur, z.B. 80°C, erwärmt und der Trocknungsvorgang so lange wiederholt wird, bis das Trocknungsgut den gewünschten niedrigen Feuchtigkeitsgehalt aufweist.5. The method according to claim 4, characterized in that after the condensation drying caused by lowering the temperature of the material to be dried below a preselected value, the material to be dried again to the initial temperature, for example 80 ° C, and the drying process so is repeated until the material to be dried has the desired low moisture content.
EP19850890167 1984-07-26 1985-07-25 Process for drying delicate products, e.g. wood Expired EP0170648B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT2424/84 1984-07-26
AT242484A AT385840B (en) 1984-07-26 1984-07-26 METHOD FOR DRYING SENSITIVE GOODS, e.g. WOOD

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EP0170648A1 true EP0170648A1 (en) 1986-02-05
EP0170648B1 EP0170648B1 (en) 1988-08-31

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AT (1) AT385840B (en)
CS (1) CS271318B2 (en)
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2604245A1 (en) * 1986-09-19 1988-03-25 Gautreau Jean Paul Process for drying hygroscopic products of great thickness, especially wood
US5228209A (en) * 1991-03-23 1993-07-20 Reinhard Brunner Apparatus for drying out wood
US5595000A (en) * 1995-01-17 1997-01-21 U.S. Natural Resources, Inc. No-vent dry kiln
WO1998045653A1 (en) * 1997-04-09 1998-10-15 Pohjois-Suomen Kuivausteknikka Oy Method and apparatus for extracting moisture and/or mold from a structure of a building
WO1999023430A1 (en) 1997-11-04 1999-05-14 Plestenjak Joze A drying device
FR2781180A1 (en) * 1998-07-17 2000-01-21 Fours Et Bruleurs Rey Torrefaction reactor for processing wood waste, has sealed chamber operating discontinuously, arrangement for stirring the air to enhance heating, and arrangement to stress the wood
FR2919921A1 (en) * 2007-08-06 2009-02-13 Groupe Solu Allience Sarl Artificial pre-drying device for wood, has thermodynamic technical modules each positioned at floor/ceiling in enclosure and connected to exchanger positioned outside enclosure to use calorific exchange capacity of exterior air
WO2015068126A1 (en) 2013-11-06 2015-05-14 Innovative Wood Drying & Consulting Amenda Stanislaw A drying system, in particular for drying wood and a method of drying in such a system
CN105268612A (en) * 2015-11-20 2016-01-27 中机中联工程有限公司 Water-based paint drying system and drying method

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT405331B (en) * 1997-02-03 1999-07-26 Eisbaer Air Tec Entfeuchtungst Method of drying articles and materials by means of air
AT408575B (en) * 1997-10-07 2002-01-25 Wolf Systembau Gmbh & Co Kg METHOD FOR DIELECTRIC DRYING OF WOOD

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE823280C (en) * 1949-08-27 1951-12-03 Otto Kiefer Dipl Kfm Automatic fresh and exhaust air control for dryers with drying temperatures above 100íÒC, especially for drying wood
DE2457654B2 (en) * 1973-12-18 1976-09-23 Pretema AG, Birmensdorf, Zürich (Schweiz) PROCESS FOR DRYING HYGROSCOPIC GOODS WITH FIBER STRUCTURE LIKE WOOD AND CARDBOARD

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE823280C (en) * 1949-08-27 1951-12-03 Otto Kiefer Dipl Kfm Automatic fresh and exhaust air control for dryers with drying temperatures above 100íÒC, especially for drying wood
DE2457654B2 (en) * 1973-12-18 1976-09-23 Pretema AG, Birmensdorf, Zürich (Schweiz) PROCESS FOR DRYING HYGROSCOPIC GOODS WITH FIBER STRUCTURE LIKE WOOD AND CARDBOARD

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2604245A1 (en) * 1986-09-19 1988-03-25 Gautreau Jean Paul Process for drying hygroscopic products of great thickness, especially wood
US5228209A (en) * 1991-03-23 1993-07-20 Reinhard Brunner Apparatus for drying out wood
US5595000A (en) * 1995-01-17 1997-01-21 U.S. Natural Resources, Inc. No-vent dry kiln
WO1998045653A1 (en) * 1997-04-09 1998-10-15 Pohjois-Suomen Kuivausteknikka Oy Method and apparatus for extracting moisture and/or mold from a structure of a building
WO1999023430A1 (en) 1997-11-04 1999-05-14 Plestenjak Joze A drying device
FR2781180A1 (en) * 1998-07-17 2000-01-21 Fours Et Bruleurs Rey Torrefaction reactor for processing wood waste, has sealed chamber operating discontinuously, arrangement for stirring the air to enhance heating, and arrangement to stress the wood
WO2000004328A1 (en) * 1998-07-17 2000-01-27 Fours Et Bruleurs Rey Reactor for wood retification
FR2919921A1 (en) * 2007-08-06 2009-02-13 Groupe Solu Allience Sarl Artificial pre-drying device for wood, has thermodynamic technical modules each positioned at floor/ceiling in enclosure and connected to exchanger positioned outside enclosure to use calorific exchange capacity of exterior air
WO2015068126A1 (en) 2013-11-06 2015-05-14 Innovative Wood Drying & Consulting Amenda Stanislaw A drying system, in particular for drying wood and a method of drying in such a system
CN105268612A (en) * 2015-11-20 2016-01-27 中机中联工程有限公司 Water-based paint drying system and drying method

Also Published As

Publication number Publication date
DE3564736D1 (en) 1988-10-06
CS271318B2 (en) 1990-09-12
AT385840B (en) 1988-05-25
CS549885A2 (en) 1990-02-12
EP0170648B1 (en) 1988-08-31
ATA242484A (en) 1987-10-15

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