EP0312888B1 - Drying plant for building panels - Google Patents
Drying plant for building panels Download PDFInfo
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- EP0312888B1 EP0312888B1 EP88116852A EP88116852A EP0312888B1 EP 0312888 B1 EP0312888 B1 EP 0312888B1 EP 88116852 A EP88116852 A EP 88116852A EP 88116852 A EP88116852 A EP 88116852A EP 0312888 B1 EP0312888 B1 EP 0312888B1
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- Prior art keywords
- drying
- frequency
- panels
- convection
- zone
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B25/00—Details of general application not covered by group F26B21/00 or F26B23/00
- F26B25/22—Controlling the drying process in dependence on liquid content of solid materials or objects
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B15/00—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form
- F26B15/10—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions
- F26B15/12—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions the lines being all horizontal or slightly inclined
- F26B15/18—Machines or apparatus for drying objects with progressive movement; Machines or apparatus with progressive movement for drying batches of material in compact form with movement in a path composed of one or more straight lines, e.g. compound, the movement being in alternate horizontal and vertical directions the lines being all horizontal or slightly inclined the objects or batches of materials being carried by endless belts
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- 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
- F26B3/32—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action
- F26B3/34—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects
- F26B3/343—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects in combination with convection
Definitions
- the invention relates to a method for drying building boards, in particular gypsum fiber boards and a dryer system for carrying out the method, the boards being placed on a treadmill for drying and the water content contained in the boards being removed by supplying heat.
- Such dryer systems for building boards are already known as convection dryers.
- the building boards to be dried are moved one after the other into the convection dryer on a treadmill and blown there from above and below with hot air of different temperatures, which gradually leads to the undesirable water content contained in the building boards due to the relatively high air temperatures of around 80 ° C to 240 ° C is withdrawn.
- drying times between a few minutes and an hour or more can be expected for thicker materials.
- Significantly thicker boards, in particular gypsum fiber or gypsum particle boards with a thickness of more than 30 mm result in very long drying times of up to 6 hours and more.
- With an hourly output of just 130 m2 a four-tier dryer with a length between 80 and 90 m would be required. This results in price disadvantages, be it in terms of machine price or the required length of the building.
- the air is exposed to high temperatures for too long, the material, especially on the surface, suffers considerable damage and thus also loss of strength, for example due to the dehydration of the gypsum.
- DE-PS 833 987 a device for drying wet nonwoven is known.
- the fiber layer on gas-permeable belts is conveyed through the device, the drying area of which consists of a combination of hot steam nozzle drying with subsequent high-frequency drying.
- the nonwoven fabric to be dried in this known device should be completely removed from the moisture; at the end of the drying process, there should be no wet spots in the nonwoven. From the aforementioned DE-PS it is not apparent that the device can be suitable as a dryer for building boards, in particular for gypsum fiber boards, which have a constantly low residual moisture at the end of the drying process in order to avoid warping of these boards.
- the object of the present invention is therefore to provide a method and a dryer system of the type mentioned at the outset to further develop that even relatively thick and highly water-containing building boards can be dried quickly and relatively inexpensively and that the dried building boards are of high quality.
- the invention has surprising advantages.
- the essence of the invention is that the drying process is first carried out from the plate surface.
- the drying process is interrupted if the material has a certain residual moisture content.
- the residual drying is then carried out to a desired residual moisture level from the inside of the material, whereby otherwise disadvantageous, but desirable water components reach the already pre-dried surface of the building boards and there, especially with thick gypsum-bound building boards, the surface is re-moistened and thus the strength of the Increase building boards because the already interrupted setting process starts again and can continue undisturbed.
- the invention preferably provides that the residual moisture of the building boards is kept constant by intervening in one of the drying stages or by changing the throughput speed.
- An embodiment of the invention provides that the convection dryer is designed as a floor dryer, with hot air nozzles arranged at the top and bottom of the drying fields, the drying fields being arranged one behind the other in the direction of falling temperature.
- a particularly rapid drying of the building boards is advantageously achieved, because the pre-drying can be carried out at an elevated temperature, and advantageously any surface areas of the building boards that have dried off are moistened again during the subsequent drying.
- the high-frequency generator is designed as a high-frequency furnace and if a first one follows the floor dryer after an entrance lock High-frequency zone and then a second high-frequency zone is arranged via a connecting link, which is followed by an exit gate.
- a total of two high-frequency generators are connected in series for the high-frequency furnace, which means that cheaper and easy-to-use high-frequency generators can be used overall.
- the treadmill arranged in the high-frequency furnace is designed as a glass fiber conveyor belt.
- the glass fiber ribbon does not impair the high-frequency properties of the high-frequency furnace, so that the energy generated only benefits the building boards to be dried in a desired manner.
- the invention consists in that a combination between a convection dryer 6 and a high-frequency furnace 10 or high-frequency generator is used.
- a loading table 1 is provided which is adjustable in height and via which the building boards to be dried are entered into the floor dryer 6 in the form of, for example, four floors 2 to 5.
- the convection dryer 6 is accordingly designed as a floor dryer, ie the plates are located at levels 2 to 5 at a distance from one another and are blown or acted upon by hot air of different temperatures from below and above. It is important here that there is a relatively high air temperature of, for example, 240 ° C. at the entrance of the floor dryer 6 and that there is an air temperature of 80 ° C. at the outlet of the floor dryer in order to achieve appropriate cooling of the building boards.
- the number of fields 7 used for the floor dryer 6 depends on the desired and required production output.
- a removal station 8 is arranged, on which the dried plates are put in again one level at a time and at the outlet of the removal station 8 a removal table 9 is arranged, each of which picks up a building board from one floor and feeds it to the high-frequency furnace 10.
- the high-frequency furnace 10 consists of an entrance lock 11 and has a first high-frequency zone 12, which is connected to a second high-frequency zone 14 via a connecting element 13.
- An output lock 15 is arranged at the output of this high-frequency furnace 10.
- the entrance lock 11 and the exit lock 15 serve to ensure that the high-frequency steel generated in the high-frequency furnace 10 does not penetrate to the outside; it becomes a radio frequency-tight Completed in the sense of maintaining a constant low residual moisture.
- the finished, dried building panels then leave the system in the direction of arrow 16.
- FIG. 2 shows a drying diagram of a relatively thick building board, which is explained in more detail in FIG. 3.
- FIG. 3 schematically shows a section through a building board, such as is present in the area of the removal station 8 or the removal table 9.
- This plate 17 has a moist core 18 and zones 19 and 20 surrounding the core, which are pre-dried by the convection dryer 6. It has now been found that when the plate 17 leaves the floor dryer 6, an unavoidably dehydrated layer 21, 22 is already formed on the top and bottom of the plate 17, because the water of hydration on the surface is removed by drying in the floor dryer becomes.
- the main advantages of the present invention are only achieved if a convection dryer 6 is followed by a high-frequency furnace 10; The advantages are not achieved if the high-frequency oven were connected upstream of a convection dryer in order to achieve a certain predrying. What is important is the fact that an upper limit of the electrical energy to be supplied in the high-frequency furnace is not exceeded; then steam bubbles would form during the drying process and these steam bubbles would lead to the tearing of the plate 17 or at least to the formation of cracks in partial areas.
- the power in the high-frequency furnace is therefore regulated so that only water and water vapor particles reach the surface of the building boards without further bubble formation.
- the treadmill arranged in the high-frequency furnace is advantageously designed as a glass fiber conveyor belt. At a frequency of the high-frequency furnace of approximately 14 MHz, it does not suffer any functional impairments and does not adversely affect the drying process.
- the residual moisture in the building boards is recorded by suitable measuring devices and can be kept constant by various methods, for example by varying the throughput speed or by regulating the power of the high-frequency field.
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Description
Die Erfindung betrifft ein Verfahren zum Trocknen von Bauplatten, insbesondere Gipsfaserplatten und eine Trockneranlage zur Durchführung des Verfahrens, wobei die Platten zur Trocknung auf ein Laufband aufgelegt werden und der in den Platten enthaltene Wasseranteil durch Zuführen von Wärme entzogen wird.The invention relates to a method for drying building boards, in particular gypsum fiber boards and a dryer system for carrying out the method, the boards being placed on a treadmill for drying and the water content contained in the boards being removed by supplying heat.
Derartige Trockneranlagen für Bauplatten sind bereits als Konvektionstrockner bekannt. Die zu trocknenden Bauplatten werden auf einem Laufband hintereinander in den Konvektionstrockner eingefahren und dort von oben und unten mit Heißluft unterschiedlicher Temperatur angeblasen, wodurch nach und nach durch die relativ hohen Lufttemperaturen von etwa 80° C bis 240° C der in den Bauplatten enthaltene unerwünschte Wasseranteil entzogen wird.Such dryer systems for building boards are already known as convection dryers. The building boards to be dried are moved one after the other into the convection dryer on a treadmill and blown there from above and below with hot air of different temperatures, which gradually leads to the undesirable water content contained in the building boards due to the relatively high air temperatures of around 80 ° C to 240 ° C is withdrawn.
Je nach Plattenstärke und anderen physikalischen Bedingungen, wie z.B. Temperatur, Luftgeschwindigkeit usw., muß man mit Trocknungszeiten zwischen wenigen Minuten und einer Stunde und mehr bei dickeren Materialen rechnen. Wesentlich stärkere Platten, insbesondere von mehr als 30 mm starke Gipsfaser- oder Gipsspanplatten, ergeben sehr lange Trocknungszeiten von bis zu 6 Stunden und mehr. Bei einer Stundenleistung von nur 130 m² wäre dafür ein Vier-Etagentrockner mit einer Länge zwischen 80 und 90 m erforderlich. Daraus resultieren preisliche Nachteile, sei es bezüglich Maschinenpreis oder erforderlicher Gebäudelänge. Dazu kommt, daß durch zu langes Einwirken von Luft mit hohen Temperaturen das Material, speziell an der Oberfläche, erheblichen Schaden und damit auch Festigkeitsverluste erleidet, z.B. durch die Dehydratisierung des Gipses.Depending on the board thickness and other physical conditions, such as temperature, air speed, etc., drying times between a few minutes and an hour or more can be expected for thicker materials. Significantly thicker boards, in particular gypsum fiber or gypsum particle boards with a thickness of more than 30 mm, result in very long drying times of up to 6 hours and more. With an hourly output of just 130 m², a four-tier dryer with a length between 80 and 90 m would be required. This results in price disadvantages, be it in terms of machine price or the required length of the building. In addition, if the air is exposed to high temperatures for too long, the material, especially on the surface, suffers considerable damage and thus also loss of strength, for example due to the dehydration of the gypsum.
Es sind bereits auch schon HF-Öfen bekannt, mit denen durch Wasserentzug eine Trocknung herbeigeführt wurde, was aber bislang nur in der Papierherstellung zur Vortrocknung von Papier- und Pappeprodukten oder auch zur Komplett-Trocknung derartiger Produkte gelang, wobei allerdings nachteilig sehr hohe Leistungsdichten und entsprechend hohe Betriebskosten benötigt wurden.HF ovens are already known which have been used for drying by removing water, but so far this has only been possible in paper production for pre-drying paper and cardboard products or for complete drying of such products, although disadvantageously very high power densities and correspondingly high operating costs were required.
Aus der DE-PS 833 987 ist eine Einrichtung zum Trocknen von nassem Faservlies bekannt. Hier wird die Faserschicht auf gasdurchlässigen Bändern durch die Einrichtung gefördert, deren Trockenbereich aus einer Kombination von einer Heißdampfdüsentrocknung mit einer nachfolgenden Hochfrequenztrocknung besteht. Dem in dieser bekannten Einrichtung zu trocknenden Faservlies soll möglichst vollständig die Feuchtigkeit entzogen werden; am Ende des Trocknungsvorganges sollen keine Naßstellen im Faservlies enthalten sein.
Aus der vorgenannten DE-PS ist nicht zu entnehmen, daß die Einrichtung geeignet sein kann als Trockneranlage für Bauplatten, insbesondere für Gipsfaserplatten zu dienen, die am Ende des Trocknungsprozesses eine konstant niedrige Restfeuchte aufweisen, um ein Verziehen dieser Platten zu vermeiden.From DE-PS 833 987 a device for drying wet nonwoven is known. Here the fiber layer on gas-permeable belts is conveyed through the device, the drying area of which consists of a combination of hot steam nozzle drying with subsequent high-frequency drying. The nonwoven fabric to be dried in this known device should be completely removed from the moisture; at the end of the drying process, there should be no wet spots in the nonwoven.
From the aforementioned DE-PS it is not apparent that the device can be suitable as a dryer for building boards, in particular for gypsum fiber boards, which have a constantly low residual moisture at the end of the drying process in order to avoid warping of these boards.
Bei den bisherigen Trockneranlagen mit Hochfrequenzöfen bestand immer der Nachteil, daß insbesondere bei größeren Materialstärken der zu trocknenden Gegenstände, wegen des Dampfaustrittes oder der Blasenbildung in Verbindung mit der erzeugten Wärme, diese zumindest in Teilbereichen zerstört werden konnten.In the previous dryer systems with high-frequency ovens there was always the disadvantage that, especially in the case of larger material thicknesses of the objects to be dried, because of the steam discharge or the formation of bubbles in connection with the heat generated, these could be destroyed at least in some areas.
Aus diesen Gründen wurden bislang für die Trocknung von Bauplatten Hochfrequenzöfen nicht verwendet, sondern diese nur für die Trocknung von dünnwandigen Produkten, insbesondere aus Papier, Faservlies o.dgl. eingesetzt.For these reasons, high-frequency ovens have not hitherto been used for drying building boards, but rather only for drying thin-walled products, in particular made of paper, nonwoven fabric or the like. used.
Aufgabe der vorliegenden Erfindung ist es daher, ein Verfahren und eine Trockneranlage der eingangs genannten Art so weiterzubilden, daß auch relativ dicke und stark wasserhaltige Bauplatten schnell und relativ kostengünstig getrocknet werden können und daß die getrockneten Bauplatten von hoher Qualität sind.The object of the present invention is therefore to provide a method and a dryer system of the type mentioned at the outset to further develop that even relatively thick and highly water-containing building boards can be dried quickly and relatively inexpensively and that the dried building boards are of high quality.
Die Aufgabe der Erfindung wird durch die kennzeichnenden Merkmale der Patentansprüche 1 und 2 gelöst.The object of the invention is achieved by the characterizing features of
Durch die Erfindung ergeben sich überraschende Vorteile. Das Wesen der Erfindung liegt darin, daß der Trocknungsvorgang zunächst von der Plattenoberfläche her durchgeführt wird. Um eine Schädigung der zu trocknenden Platten zu vermeiden, wird bei einer bestimmten Restfeuchte des Materials der Trocknungsvorgang unterbrochen. Die Resttrocknung wird dann bis zu einer erwünschten Restfeuchte von der Materialinnenseite her durchgeführt, wobei sonst nachteilige, hier aber erwünschte Wasserbestandteile an die schon vorgetrocknete Oberfläche der Bauplatten gelangen und dort, insbesondere bei dicken gipsgebundenen Bauplatten, die Oberfläche erneut befeuchtet wird und damit die Festigkeit der Bauplatten erhöhen, weil der möglicherweise schon unterbrochene Abbindevorgang erneut anläuft und im weiteren ungestört ablaufen kann.The invention has surprising advantages. The essence of the invention is that the drying process is first carried out from the plate surface. In order to avoid damaging the panels to be dried, the drying process is interrupted if the material has a certain residual moisture content. The residual drying is then carried out to a desired residual moisture level from the inside of the material, whereby otherwise disadvantageous, but desirable water components reach the already pre-dried surface of the building boards and there, especially with thick gypsum-bound building boards, the surface is re-moistened and thus the strength of the Increase building boards because the already interrupted setting process starts again and can continue undisturbed.
Beim Trocknen in Konvektionstrocknern entsteht an der Oberseite und Unterseite der Bauplatten leicht eine dehydratisierte Schicht, weil eben durch die Trocknung das Hydratwasser an den Oberflächen entfernt wird. Es kommt hierbei zu einer gewissen Destabilisierung der Oberflächenschichten, wobei diese wegen fehlender Feuchtigkeit kreideförmig werden, wodurch die Festigkeit der Bauplatte beeinträchtigt wird. Derartig dehydratisierte Schichten hatte man bisher bei der alleinigen Verwendung von Konvektionstrocknern inkaufnehmen müssen.
Mit der Erfindung werden diese Nachteile vermieden, weil durch die Trocknung in einem nachgeschalteten Hochfrequenzofen Wasser und Wasserdampf-Partikel von innen nach außen diffundieren und in die dehydratisierten Schichten eindringen.
Mit der Erfindung wird somit bei schneller und relativ kostengünstiger Trocknung durch die erneute Verfestigung der Oberflächenschichten eine gegenüber sonstigen Trocknern erhöhte Festigkeit der Bauplatten erreicht.When drying in convection dryers, a dehydrated layer easily forms on the top and bottom of the building boards, because the drying process removes the water of hydration from the surfaces. This leads to a certain destabilization of the surface layers, which become chalk-shaped due to the lack of moisture, which impairs the strength of the building board. Such dehydrated layers had previously had to be accepted when using only convection dryers.
These disadvantages are avoided with the invention, because water and water vapor particles diffuse from the inside to the outside and into by drying in a downstream high-frequency oven the dehydrated layers penetrate.
The invention thus achieves an increased strength of the building boards compared to other dryers in the case of quick and relatively inexpensive drying due to the renewed consolidation of the surface layers.
Mit der Erfindung ist es vorzugsweise vorgesehen, daß die Restfeuchte der Bauplatten durch Leistungseingriff in eine der Trocknungsstufen oder durch Änderung der Durchlaufgeschwindigkeit konstant gehalten wird.The invention preferably provides that the residual moisture of the building boards is kept constant by intervening in one of the drying stages or by changing the throughput speed.
Hierbei wird insbesondere bei der Vortrocknung der Bauplatten im Konvektionstrockner eine gewisse Restfeuchte in den Bauplatten belassen, die im weiteren bei der Nachtrocknung dazu benutzt wird, daß sich die Oberfläche der Bauplatten bei erneuter Befeuchtung weiter verfestigt. Insgesamt wird die Trocknung nur soweit durchgeführt, daß auch nach Durchlaufen des Hochfrequenzofens ein gewisser Teil von Restfeuchte in den Bauplatten verbleibt, um derart eine Stabilisierung der Platten zu erreichen.In this case, in particular during the predrying of the building boards in the convection dryer, a certain residual moisture is left in the building boards, which is subsequently used in the post-drying to further solidify the surface of the building boards when they are moistened again. Overall, the drying is only carried out to such an extent that even after passing through the high-frequency furnace, a certain portion of residual moisture remains in the building boards in order to stabilize the boards in this way.
Ein Ausführungsbeispiel der Erfindung sieht vor, daß der Konvektionstrockner als Etagentrockner ausgebildet ist, mit in den Trockenfeldern oben und unten angeordneten Heißluftdüsen, wobei die Trockenfelder in Richtung sinkender Temperatur hintereinander angeordnet sind.An embodiment of the invention provides that the convection dryer is designed as a floor dryer, with hot air nozzles arranged at the top and bottom of the drying fields, the drying fields being arranged one behind the other in the direction of falling temperature.
Hierbei wird vorteilhaft ein besonders schnelles Abtrocknen der Bauplatten erreicht, weil beim Vortrocknen mit erhöhter Temperatur gefahren werden kann und vorteilhaft etwa abgetrocknete Oberflächenbereiche der Bauplatten bei der Nachtrocknung wieder befeuchtet werden.In this case, a particularly rapid drying of the building boards is advantageously achieved, because the pre-drying can be carried out at an elevated temperature, and advantageously any surface areas of the building boards that have dried off are moistened again during the subsequent drying.
Es ist von Vorteil, wenn der Hochfrequenzgenerator als Hochfrequenzofen ausgebildet ist und wenn im Anschluß an den Etagentrockner nach einer Eingangsschleuse eine erste Hochfrequenzzone und nachfolgend über ein Verbindungsglied eine zweite Hochfrequenzzone angeordnet ist, an die sich eine Ausgangsschleuse anschließt.It is advantageous if the high-frequency generator is designed as a high-frequency furnace and if a first one follows the floor dryer after an entrance lock High-frequency zone and then a second high-frequency zone is arranged via a connecting link, which is followed by an exit gate.
Hierbei sind für den Hochfrequenzofen insgesamt zwei Hochfrequenzgeneratoren in Hintereinanderschaltung vorgesehen, wodurch insgesamt billigere und einfach zu bedienende Hochfrequenzgeneratoren verwendet werden können.A total of two high-frequency generators are connected in series for the high-frequency furnace, which means that cheaper and easy-to-use high-frequency generators can be used overall.
In besonderer Ausgestaltung ist das in dem Hochfrequenzofen angeordnete Laufband als Glasfaser-Transportband ausgebildet. Das Glasfaserband beeinträchtigt nicht die Hochfrequenzeigenschaften des Hochfrequenzofens, so daß die erzeugte Energie in erwünschter Weise allein den zu trocknenden Bauplatten zugute kommt.In a special embodiment, the treadmill arranged in the high-frequency furnace is designed as a glass fiber conveyor belt. The glass fiber ribbon does not impair the high-frequency properties of the high-frequency furnace, so that the energy generated only benefits the building boards to be dried in a desired manner.
Im folgenden wird die Erfindung anhand einer lediglich einen Ausführungsweg darstellenden Zeichnung näher erläutert. Hierbei gehen aus der Zeichnung und ihrer Beschreibung weitere erfindungswesentliche Merkmale und Vorteile der Erfindung hervor.The invention is explained in more detail below with reference to a drawing which shows only one possible embodiment. Further features and advantages of the invention which are essential to the invention are evident from the drawing and its description.
Die Erfindung soll nachstehend anhand eines Ausführungsbeispieles näher erläutert werden. Es zeigen:
- Figur 1
- einen Konvektionstrockner mit einzelnen Trockenfeldern und nachgeschaltetem Hochfrequenzofen in schematischer Darstellung;
Figur 2- ein Trocknungsdiagramm einer relativ dicken Bauplatte mit Darstellung der relativen Feuchtigkeit, abhängig von der Trocknungszeit;
Figur 3- eine zur Trocknung vorgesehene relativ dicke Bauplatte im Schnitt.
- Figure 1
- a convection dryer with individual drying fields and downstream high-frequency furnace in a schematic representation;
- Figure 2
- a drying diagram of a relatively thick building board showing the relative humidity, depending on the drying time;
- Figure 3
- a relatively thick building board intended for drying on average.
Die Erfindung besteht nach Figur 1 darin, daß eine Kombination zwischen einem Konvektionstrockner 6 und einem Hochfrequenzofen 10 bzw. Hochfrequenzgenerator verwendet wird.According to FIG. 1, the invention consists in that a combination between a
Nach Figur 1 ist ein Beschickungstisch 1 vorhanden, der höhenverstellbar ausgebildet ist und über den die zu trocknenden Bauplatten in Form von beispielsweise vier Etagen 2 bis 5 dem Etagentrockner 6 eingegeben werden.
Der Konvektionstrockner 6 ist demnach als Etagentrockner ausgebildet, d.h. die Platten liegen in Etagen 2 bis 5 in Abstand voneinander vor und werden von unten und oben mit Heißluft unterschiedlicher Temperatur beblasen oder beaufschlagt.
Wichtig ist hierbei, daß am Eingang des Etagentrockners 6 eine relativ hohe Lufttemperatur von beispielsweise 240°C herrscht und am Ausgang des Etagentrockners eine Lufttemperatur von 80°C besteht, um eine entsprechende Kühlung der Bauplatten zu erreichen.
Die Anzahl der verwendeten Felder 7 für den Etagentrockner 6 hängt von der gewünschten und geforderten Produktionsleistung ab. Bei der Trocknung von derartigen Bauplatten werden beispielsweise insgesamt zehn Felder 7 verwendet.
Am Ausgang des Etagentrockners 6 ist eine Entnahmestation 8 angeordnet, auf welcher die getrockneten Platten etagenweise wieder aufgegeben werden und am Auslauf der Entnahmestation 8 ist ein Entnahmetisch 9 angeordnet, der jeweils eine Bauplatte von einer Etage aufnimmt und dem Hochfrequenzofen 10 zuführt.According to FIG. 1, a loading table 1 is provided which is adjustable in height and via which the building boards to be dried are entered into the
The
It is important here that there is a relatively high air temperature of, for example, 240 ° C. at the entrance of the
The number of
At the exit of the
Der Hochfrequenzofen 10 besteht aus einer Eingangsschleuse 11 und weist eine erste Hochfrequenzzone 12 auf, die über ein Verbindungsglied 13 mit einer zweiten Hochfrequenzzone 14 verbunden ist. Am Ausgang dieses Hochfrequenzofens 10 ist eine Ausgangsschleuse 15 angeordnet.
Die Eingangsschleuse 11 und die Ausgangsschleuse 15 dient dazu, daß die im Hochfrequenzofen 10 erzeugte Hochfrequenzstahlung nicht nach außen dringt; es wird demnach ein hochfrequenzdichter Abschluß im Sinne der Aufrechterhaltung einer konstant niedrigen Restfeuchte erreicht.
Die fertigt getrockneten Bauplatten verlassen dann in Pfeilrichtung 16 die Anlage.The high-
The
The finished, dried building panels then leave the system in the direction of
In Figur 2 ist ein Trocknungsdiagramm einer relativ dicken Bauplatte gezeigt, die in Figur 3 noch näher erläutert wird.FIG. 2 shows a drying diagram of a relatively thick building board, which is explained in more detail in FIG. 3.
Aus Figur 2 wird deutlich, daß in dem Konvektionstrockner 6, nämlich in der Zone 24 nach Figur 2, der größte Teil der Feuchte entzogen wird. Beispielsweise wenn insgesamt eine Bauplatten-Charge einen Wassergehalt von 900 Kg aufweist, werden 800 Kg vom Konvektionstrockner 6 in der Zone 24 entfernt und nur noch die Restfeuchte im Bereich von etwa 100 Kg in der Zone 25 nach Figur 2 von dem Hochfrequenzofen 10. In Gew.-% ausgedrückt heißt dies, daß der Hochfrequenzofen 10 lediglich 3-4 Gew.-% Restfeuchte entfernt. Ein Teil von Restfeuchtigkeit verbleibt noch in den fertig getrockneten Platten, um ein Verziehen derselben zu vermeiden.
Hier liegt das Wesen der vorliegenden Erfindung, denn bisher war der Einsatz derartiger Hochfrequenzöfen zum Trocknen von Bauplatten nicht bekannt. Es war bisher nicht bekannt, die Restfeuchte, vor allem bei dicken Platten und hier wiederum bei gipsgebundenen Platten, zu entfernen, weil Nachteile, insbesondere ein Aufreißen der Platten, befürchtet wurden.From Figure 2 it is clear that in the
This is the essence of the present invention, because the use of such high-frequency ovens for drying building boards was previously unknown. It was previously not known to remove the residual moisture, especially in the case of thick boards and here again in the case of gypsum-bonded boards, because disadvantages, in particular tearing open the boards, were feared.
Die Figur 3 zeigt schematisiert einen Schnitt durch eine Bauplatte, wie sie etwa im Bereich der Entnahmestation 8 oder des Entnahmetisches 9 vorliegt. Diese Platte 17 weist einen feuchten Kern 18 und den Kern umgebende Zonen 19 und 20 auf, die durch den Konvektionstrockner 6 vorgetrocknet sind.
Es hat sich nun herausgestellt, daß, wenn die Platte 17 den Etagentrockner 6 verläßt, dann bereits eine unvermeidbar dehydratisierte Schicht 21,22 an der Oberseite und Unterseite der Platte 17 gebildet wird, weil eben durch die Trocknung im Etagentrockner das Hydratwasser an der Oberfläche entfernt wird.FIG. 3 schematically shows a section through a building board, such as is present in the area of the
It has now been found that when the
Es kommt hierbei zu einer gewissen Destabilisierung der Oberflächenschichten im Bereich der Schichten 21 und 22. Diese werden kreideförmig und beeinträchtigen die Festigkeit der Platte. Derartige dehydratisierte Schichten hatte man bisher bei der alleinigen Verwendung von Konvektionstrocknern inkaufnehmen müssen.
Mit der Erfindung wird jedoch durch den Hochfrequenzofen 10 der feuchte Kern 18 relativ schnell getrocknet, wobei nun vorteilhaft durch die vorher getrocknete Oberfläche Wasser und Wasserdampfpartikel in Pfeilrichtung 23 nach außen diffundieren und in die dehydratisierten Schichten 21,22 eindringen.
Hierdurch werden die schon getrockneten Schichten 21,22 wieder befeuchtet. Durch die Befeuchtung kommt es zu einer gewissen Hydratisierung, d.h. zu einer erneuten Verfestigung dieser Schichten, weil Hydratwasser erneut zugeführt wird und die Schichten dadurch erneut verfestigt werden.This leads to a certain destabilization of the surface layers in the area of the
With the invention, however, the
As a result, the already dried
Durch die Kombination von einem Konvektionstrockner 6 mit einem nachgeschalteten Hochfrequenzofen 10 entstehen vorteilhafte Wirkungen, als es hier zu einer erneuten Verfestigung der oberen Schichten 21,22 der Bauplatte kommt, wie es bisher nicht bekannt war.The combination of a
Die wesentlichen Vorteile der vorliegenden Erfindung werden nur dann erreicht, wenn einem Konvektionstrockner 6 ein Hochfrequenzofen 10 nachgeschaltet wird; erreicht werden die Vorteile nicht, wenn der Hochfrequenzofen einem Konvektionstrockner vorgeschaltet werden würde, um eine gewisse Vortrocknung zu erreichen.
Wichtig ist die Tatsache, daß man eine Obergrenze der zuzuführenden elektrischen Energie beim Hochfrequenzofen nicht überschreitet; dann würden sich nämlich Dampfblasen während des Trocknungsprozesses bilden und diese Dampfblasen würden zum Zerreißen der Platte 17 oder zumindest zu Rißbildungen in Teilbereichen, führen.The main advantages of the present invention are only achieved if a
What is important is the fact that an upper limit of the electrical energy to be supplied in the high-frequency furnace is not exceeded; then steam bubbles would form during the drying process and these steam bubbles would lead to the tearing of the
Die Leistung im Hochfrequenzofen wird demnach so geregelt, daß lediglich Wasser- und Wasserdampfpartikel ohne weitere Blasenbildung an die Oberfläche der Bauplatten gelangen.The power in the high-frequency furnace is therefore regulated so that only water and water vapor particles reach the surface of the building boards without further bubble formation.
Das im Hochfrequenzofen angeordnete Laufband ist vorteilhaft als Glasfaser-Transportband ausgebildet.
Bei einer Frequenz des Hochfrequenzofens von etwa 14 MHz erleidet es keine funkionellen Beeinträchtigungen und beeinflußt den Trocknungsprozeß nicht negativ.The treadmill arranged in the high-frequency furnace is advantageously designed as a glass fiber conveyor belt.
At a frequency of the high-frequency furnace of approximately 14 MHz, it does not suffer any functional impairments and does not adversely affect the drying process.
Die Restfeuchte wird bei den Bauplatten durch geeignete Messgeräte erfaßt und kann durch verschiedene Methoden konstant gehalten werden, z.B. durch Variieren der Durchlaufgeschwindigkeit oder auch durch Leistungsregelung des Hochfrequenzfeldes.The residual moisture in the building boards is recorded by suitable measuring devices and can be kept constant by various methods, for example by varying the throughput speed or by regulating the power of the high-frequency field.
- 11
- BeschichtungstischCoating table
- 22nd
- Etagefloor
- 33rd
- Etagefloor
- 44th
- Etagefloor
- 55
- Etagefloor
- 66
- KonvektionstrocknerConvection dryer
- 77
- FelderFields
- 88th
- EntnahmestationRemoval station
- 99
- EntnahmetischRemoval table
- 1010th
- HF-OfenHF furnace
- 1111
- EingangsschleuseEntrance lock
- 1212th
- erste HF-Zonefirst RF zone
- 1313
- VerbindungsgliedConnecting link
- 1414
- zweite HF-Zonesecond RF zone
- 1515
- AusgangsschleuseExit gate
- 1616
- PfeilrichtungArrow direction
- 1717th
- BauplatteBuilding board
- 1818th
- feuchter Kernwet core
- 1919th
- ZoneZone
- 2020th
- ZoneZone
- 2121
- SchichteLayer
- 2222
- SchichteLayer
- 2323
- PfeilrichtungArrow direction
- 2424th
- ZoneZone
- 2525th
- ZoneZone
Claims (3)
- Method of drying building panels, particularly gypsum-fibre panels, according to which the panels are first dried by convection with an appropriate speed of passage through a drying plant and subsequently undergo a second, high-frequency drying stage, characterized in that the predrying takes place with the panels laid in tiers and transported thus through a pre-drying region, and with a temperature gradient between the input and the output of the predrying region, whereupon the predried panels are separated and are subjected to the secondary drying stage by the alteration of the speed of passage or by the regulation of the strength of the high-frequency field, in a manner such that, at the end of the whole drying process, the panels have a constant residual moisture.
- Drying plant for implementing the method according to Claim 1, constituted by a convection drier which carries out a pre-drying stage, downstream of which there is a high-frequency generator for carrying out a second drying stage, and which is provided with a belt conveyor carrying the panels and extending through the drying plant, characterized in that the convection drier (6) is a tiered drier which is composed of drying regions (7) equipped with individual hot-air nozzles arranged in succession, and which has a temperature gradient from its input towards its output, and in that the high-frequency generator is a high-frequency oven (10), having a first high-frequency zone (12) which is connected to an input lock (11) and to which a second high-frequency zone (14) is connected by means of a connecting element (13), the second high-frequency zone (14) opening into an output lock (15).
- Drying plant according to Claim 2, characterized in that the belt conveyor in the high-frequency oven (10) is a glass fibre conveyor belt.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19873735242 DE3735242A1 (en) | 1987-10-17 | 1987-10-17 | DRYER FOR BUILDING BOARDS |
| DE3735242 | 1987-10-17 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0312888A2 EP0312888A2 (en) | 1989-04-26 |
| EP0312888A3 EP0312888A3 (en) | 1989-06-28 |
| EP0312888B1 true EP0312888B1 (en) | 1994-01-19 |
Family
ID=6338572
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP88116852A Expired - Lifetime EP0312888B1 (en) | 1987-10-17 | 1988-10-11 | Drying plant for building panels |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4890394A (en) |
| EP (1) | EP0312888B1 (en) |
| JP (1) | JPH01212886A (en) |
| DE (2) | DE3735242A1 (en) |
| FI (1) | FI884762A (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3811157A1 (en) * | 1988-03-31 | 1989-10-19 | K & F Voringer Gewoelbe Und Au | METHOD FOR THE PRODUCTION OF CURVED FLAT-LIKE DESIGN ELEMENTS HAVING GYPSUM MATERIAL |
| AT403713B (en) * | 1990-08-27 | 1998-05-25 | Innotech Betriebstechnikgesell | INSULATION BOARD FROM WOOD MATERIAL AND METHOD FOR THE PRODUCTION THEREOF |
| US5309650A (en) * | 1991-08-29 | 1994-05-10 | Abb Flakt, Inc. | Method and apparatus for ventilating a paint baking oven |
| US5235757A (en) * | 1991-08-29 | 1993-08-17 | Abb Flakt, Inc. | Method and apparatus for distributing airflow in a paint baking oven convection zone |
| DE29505419U1 (en) * | 1995-03-30 | 1995-07-13 | Kollmer, Hansjakob, 77933 Lahr | Device for drying and hardening orthopedic molded parts made of plaster |
| FR2739999B1 (en) * | 1995-10-17 | 1998-01-02 | Inst Textile De France | MATERIAL HOLDER FOR APPLYING A HIGH FREQUENCY ELECTROMAGNETIC FIELD TO A STACK OF MATERIALS, AND PROCESSING ENCLOSURE, IN PARTICULAR A HIGH FREQUENCY TEXTILE QUICK DRYER EQUIPPED WITH SUCH A MATERIAL HOLDER |
| DE10038169A1 (en) * | 2000-08-04 | 2002-03-07 | November Ag Molekulare Medizin | Synthetic particle for marking a substance |
| FR2822746B1 (en) * | 2001-04-03 | 2003-06-20 | Lafarge Platres | PLASTERBOARD MANUFACTURING UNIT |
| US6689407B2 (en) | 2001-06-25 | 2004-02-10 | Goodmark Foods, Inc. | Enhanced capacity food processing systems with efficient space utilization |
| US6793068B2 (en) | 2002-02-04 | 2004-09-21 | Conagra Foods, Inc. | Food transport routing systems, devices, and guides for food processing systems and related methods |
| US6713107B2 (en) * | 2002-03-01 | 2004-03-30 | Conagra Foods, Inc. | Airflow distribution systems for food processors |
| DE102004056795B4 (en) * | 2004-11-24 | 2006-10-12 | Lindauer Dornier Gmbh | Multi-day microwave continuous dryers for plate-shaped products, in particular fibreboards |
| US8388926B2 (en) | 2006-01-13 | 2013-03-05 | Certainteed Gypsum, Inc. | System and method for the production of gypsum using heat recovery |
| PL1971813T3 (en) * | 2006-01-13 | 2017-01-31 | Certainteed Gypsum, Inc. | System and method for the production of alpha type gypsum using heat recovery |
| DE102006037815A1 (en) * | 2006-08-12 | 2008-02-14 | Lindauer Dornier Gmbh | Transport device for a microwave treatment plant |
| JP4875543B2 (en) * | 2007-06-11 | 2012-02-15 | 西光エンジニアリング株式会社 | Paper tube drying apparatus and paper tube drying method |
| US8453343B2 (en) * | 2010-01-12 | 2013-06-04 | Hot Woods, LLC | Method of treatment of wooden items |
| CN103090643A (en) * | 2013-01-14 | 2013-05-08 | 四川省食品发酵工业研究设计院 | Citrus juice-squeezing hide-trimming-segmentation drying method |
| ES2702554T3 (en) | 2016-04-26 | 2019-03-01 | Metalquimia Sa | Plant and air drying method of chopped food |
| CN109269277A (en) * | 2018-09-15 | 2019-01-25 | 江西植提庄园健康产业有限公司 | A kind of borneol blast drier |
| DE102019002671A1 (en) * | 2019-04-11 | 2020-10-15 | Grenzebach Bsh Gmbh | Method for drying sheet materials and drying device |
| FR3112304B1 (en) * | 2020-07-10 | 2022-10-14 | Exelsius | System for treating an object comprising a material to be crosslinked. |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2408434A (en) * | 1942-03-02 | 1946-10-01 | Julius W Mann | Method and apparatus for drying materials uniformly throughout their mass |
| US2543618A (en) * | 1946-12-19 | 1951-02-27 | Wood Electro Process Company | Apparatus for drying wood |
| US2567983A (en) * | 1946-12-19 | 1951-09-18 | Wood Electro Process Company | Method of drying lumber |
| DE833987C (en) * | 1950-05-23 | 1952-05-23 | Hermann Haas Jun Dipl Ing | Device for drying wet nonwovens |
| US2909850A (en) * | 1956-02-23 | 1959-10-27 | Celotex Corp | Drying gypsum wallboard |
| US3277580A (en) * | 1963-07-05 | 1966-10-11 | Hammtronics Systems Inc | Method and apparatus for drying |
| DE1729250A1 (en) * | 1967-03-17 | 1971-06-16 | Lahden Rautateollisuus Oy | Method and device in dryers for equalizing the final moisture in materials |
| US3435535A (en) * | 1967-12-04 | 1969-04-01 | Robert C Blair | Means and method for controlling the edge-drying of gypsum wallboard |
| US3548513A (en) * | 1968-05-06 | 1970-12-22 | Frederick T Taylor | Dryer with ejectors |
| US3775860A (en) * | 1971-06-03 | 1973-12-04 | Mac Millan Bloedel Ltd | Method for drying materials with microwave energy |
| JPS5022342A (en) * | 1973-06-30 | 1975-03-10 | ||
| JPS5077957A (en) * | 1973-11-12 | 1975-06-25 | ||
| CH583404A5 (en) * | 1975-03-18 | 1976-12-31 | Patelhold Patentverwertung | |
| US4148476A (en) * | 1975-05-06 | 1979-04-10 | Ab Svenska Flaktfabriken | Conveyor for lamellar material |
| DE2613512A1 (en) * | 1976-03-30 | 1977-10-06 | Buettner Schilde Haas Ag | TWO-STAGE DRYING PROCESS AND DRYING SYSTEM |
| DE2721965C2 (en) * | 1977-05-14 | 1986-09-11 | Babcock-BSH AG vormals Büttner-Schilde-Haas AG, 4150 Krefeld | Process for monitoring and controlling the drying of veneer sheets in a continuous process |
| DE2816551C3 (en) * | 1978-04-17 | 1981-11-26 | SIEMENS AG AAAAA, 1000 Berlin und 8000 München | Drying control on a paper machine |
| GB2110803B (en) * | 1981-10-23 | 1985-05-01 | Balfour And Co Limited Henry | Microwave drying of granular materials |
| JPS58117986A (en) * | 1981-12-29 | 1983-07-13 | 段谷産業株式会社 | Method and device for drying wood |
| US4622757A (en) * | 1984-12-24 | 1986-11-18 | Energy International, Inc. | Cogeneration microwave food dryer |
-
1987
- 1987-10-17 DE DE19873735242 patent/DE3735242A1/en active Granted
-
1988
- 1988-10-11 EP EP88116852A patent/EP0312888B1/en not_active Expired - Lifetime
- 1988-10-11 DE DE88116852T patent/DE3887257D1/en not_active Expired - Fee Related
- 1988-10-14 FI FI884762A patent/FI884762A/en not_active Application Discontinuation
- 1988-10-17 JP JP63261271A patent/JPH01212886A/en active Pending
- 1988-10-17 US US07/258,580 patent/US4890394A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0312888A2 (en) | 1989-04-26 |
| FI884762A0 (en) | 1988-10-14 |
| DE3735242A1 (en) | 1989-04-27 |
| US4890394A (en) | 1990-01-02 |
| EP0312888A3 (en) | 1989-06-28 |
| JPH01212886A (en) | 1989-08-25 |
| DE3887257D1 (en) | 1994-03-03 |
| DE3735242C2 (en) | 1990-12-20 |
| FI884762A (en) | 1989-04-18 |
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