EP0292717A2 - Timber drying device - Google Patents
Timber drying device Download PDFInfo
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- EP0292717A2 EP0292717A2 EP88106746A EP88106746A EP0292717A2 EP 0292717 A2 EP0292717 A2 EP 0292717A2 EP 88106746 A EP88106746 A EP 88106746A EP 88106746 A EP88106746 A EP 88106746A EP 0292717 A2 EP0292717 A2 EP 0292717A2
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- Prior art keywords
- air
- wood
- drying
- moisture
- stack
- Prior art date
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- 238000001035 drying Methods 0.000 title claims abstract description 62
- 239000002023 wood Substances 0.000 claims abstract description 54
- 238000000034 method Methods 0.000 claims description 13
- 238000010438 heat treatment Methods 0.000 claims description 4
- 238000005259 measurement Methods 0.000 claims description 2
- 238000009423 ventilation Methods 0.000 claims 1
- 230000001419 dependent effect Effects 0.000 abstract 1
- 238000005192 partition Methods 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 3
- 238000009416 shuttering Methods 0.000 description 3
- 239000000835 fiber Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000009415 formwork Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000001095 motoneuron effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
Images
Classifications
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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
- 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
- F26B21/02—Circulating air or gases in closed cycles, e.g. wholly within the drying enclosure
- F26B21/022—Circulating air or gases in closed cycles, e.g. wholly within the drying enclosure with provisions for changing the drying gas flow pattern, e.g. by reversing gas flow, by moving the materials or objects through subsequent compartments, at least two of which have a different direction of gas flow
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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
- F26B3/02—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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B2210/00—Drying processes and machines for solid objects characterised by the specific requirements of the drying good
- F26B2210/16—Wood, e.g. lumber, timber
Definitions
- the invention relates to a method for drying lumber, which has the features of the preamble of claim 1, and an apparatus for performing this method.
- a drying chamber It is known for a drying chamber to approximately calculate the air speed within the wood stack from the chamber geometry, the delivery capacity of the fans, the flow resistance of the heating registers, the size and arrangement of the wood stack, and the stacking factor, and during drying, depending on the type of wood, thickness and moisture as well as the desired quality set to suitable values by the fan speed.
- a number of parameters are not taken into account in this calculation, for example the accuracy of the stacking, so-called air short circuits, the surface properties of the wood, changes in the wood layers due to shrinkage, unsuitable stacking strips and the like, which is why the flow velocities between the individual, sawn wood layers deviate significantly from the desired value can.
- the total stack height increases the Differences in the flow velocity of the individual partial flows passing through the wood layers increase sharply. This means that the individual parts of the wood dry at different speeds. Depending on whether measuring points in better or poorly ventilated areas are chosen to regulate the drying process, there may be rejects due to excessive wood moisture, discolouration and mold growth or due to over-dried goods, whereby the costs increase with longer drying times. If, in addition, as is often unavoidable, batches of wood with different initial moisture levels are introduced, this can lead to additional drying damage such as shuttering, warping and cracks, especially if, for example, more humid batches are more aerated than drier, regulatory batches.
- the invention is therefore based on the object of providing a drying process which avoids the drying deficiencies described and moreover offers a possibility of drying different types of wood with deviations in strength and / or drying properties simultaneously in a chamber more economically and with better quality than it is possible with known methods.
- This object is achieved by a method having the features of claim 1.
- the air speed between the stacked boards is one of the parameters that have the greatest influence on the progress of drying. It is therefore possible to dry stack areas of different wood moisture, type and thickness in a given chamber climate simply by varying the flow velocities in these areas.
- the required flow velocities are set using an appropriate air velocity profile in the air inlet plane defined by the stack.
- the flow rate of the individual air streams passing through the sawn timber layers or at least of groups of these air streams is set as a function of measured values which are indirect or unrelated to the flow state
- Indirectly characteristic namely the wood moisture, the moisture gradient and / or the air speed
- the deviation of the flow speed in the channels formed by the sawn timber layers from the target value can be significantly reduced and thereby either achieve a more uniform drying or adjust the drying times of different lots to each other.
- the flow rate can be corrected. It is even possible to continuously carry out an actual value / setpoint comparison on the basis of the measured values serving as the actual value and to regulate the flow rate accordingly.
- the required air velocity profile is preferably set and changed by changing the air duct before the air enters between the sawn timber layers, since in this way a very effective influence on the flow velocity between the timber layers can be achieved even with a large stack height. If necessary, the amount and / or pressure of the air can of course also be varied between the layers of lumber before entering.
- the measured values of wood moisture and / or air speed are recorded at points which lie at different heights above the floor of the drying room. With a greater depth of the drying room, it will generally also be necessary to record the measured values at different depths, that is to say at different horizontal distances perpendicular to the direction of flow through the stack or stacks. There are limit values for the speed of a continuous air flow through the wood piles, which are usually observed in order not to jeopardize a good drying result and to achieve economical drying.
- an upper limit is determined by the type, thickness, moisture and moisture gradient as well as by the chamber climate. The feared formwork may result in this limit being exceeded for a longer period of time if the moisture gradient across the board cross-section (the moisture gradient) becomes too large when the layers of wood near the surface dry quickly. If shuttering has occurred, not only is the further drying progress slowed considerably; there is also a risk of the wood being destroyed by cracking.
- the lower limit of the continuous air speed depends on the length of the airway through the stacks. If the speed is too low, the air will reach its moisture equilibrium with the wood surface before the stack exits, and above the fiber saturation (e.g. always with freshly sawn wood) its full saturation, so that it cannot absorb any more moisture from the wood the rest of the way through the stack. As a result, an increasing wood moisture profile occurs along the airway through the stacks in the course of drying, in the case of reversing operation symmetrically to the center of the stack.
- a high speed, concentrated air stream is sequentially directed to all areas of the stack entrance.
- the concentration is achieved by a suitable position of the fans and / or air steering devices. Since at high speed the dwell time of certain air volumes within the stack is only short, they cannot get close to the moisture balance with the wood or its saturation moisture. Due to the relatively sluggish moisture transport of wood, shuttering cannot occur if the phases of high speed do not last too long.
- the temporal mean value of the air speed which is decisive for the drying progress, can easily be reduced by selecting the duration of the high speed phases for individual stacking areas to be small enough compared to the duration of the low speed.
- the duration during which a particular stacking area is exposed to the concentrated air flow is varied depending on the moisture and / or moisture gradient of the wood in this area.
- the invention is also based on the object of providing a drying device for carrying out the method according to the invention. This object is achieved by a drying device with the features of claim 5.
- the flow directing device has adjustable air guide surfaces, because by means of such air guide surfaces the required air quantities can be supplied to the different parts of the stack or the different wood parts in a simple manner depending on how large the other air quantities are. It is true that at least when the position of the fan or fans influences the air distribution to the individual gaps between the wooden layers, the fans can also be adjusted, for example by pivoting, to influence the speed of the individual air streams. As a rule, however, adjustability of the fans will only be sufficient in connection with air guiding surfaces.
- the air guiding surfaces and, if adjustable, the fans can have a manual drive.
- servomotors are preferably provided in order to be able to carry out the adjustment via a control device or a regulating device.
- the air guiding surfaces designed as deflection elements are advantageously arranged on at least one of the two ends of this flow channel. With their help, the deflection can then take place in such a way that the required air streams are applied to the inlet openings of the spaces between the wooden layers.
- air guiding surfaces designed as deflection elements can be provided at different heights on the air inlet and outlet sides of the lumber stack.
- These deflection elements can be arranged in a holder both pivotable about a horizontal axis and adjustable in the vertical direction.
- One can then sort of divide the entire stack height into several sections, within which the air flows can be adjusted or regulated independently of one another. It may therefore be desirable to be able to adjust and position the deflection elements independently of one another.
- These positions can be determined, for example, as a function of the wood moisture and the wood moisture differences derived therefrom, taking into account the height positions of the individual measuring points, by means of a process computer and converted into the necessary control commands.
- feedback potentiometers on the servomotors can record the current position.
- the flow control can also be selected so that stack parts are at least partially no longer supplied with the circulating air.
- each fan is preferably adjustable about a vertical axis depending on the others, so that the air flows can be directed to one or more areas along the chamber depth with a suitable rotation. If maximum rotation angles of more than 180 ° (eg 270 °) are selected, a reversal of the air direction can also be achieved with fans that are only designed for one direction of rotation and are therefore about 1 - 20% more efficient than reversible fans.
- each fan can preferably be adjusted independently of the others about a horizontal axis in order to direct the air flows onto selectable horizontal wood layers when suitably positioned .
- wood moisture compensation can also be achieved with different wood moisture levels in the area of the air inlet and the air outlet of the channels formed by the wood layers by reversing times of different lengths.
- air guiding surfaces on both sides of the drying room are advisable.
- a drying chamber 1 for receiving at least one wood stack 2, which consists of the lumber 3 to be dried and the stacking strips arranged between two adjacent layers of lumber, has a cubic shape in the exemplary embodiment and is provided on one end face with a gate, not shown, which during the drying process closes the drying chamber 1 tightly.
- the wood stacks 2 are arranged in the drying room 1 next to one another and possibly one behind the other, so that the stacking strips 4 extend in the transverse direction of the drying chamber 1 and a sufficiently wide space 6 remains free between the two side walls 5 of the drying chamber and the wood stacks 2.
- a partition 8 which runs parallel to the upper boundary wall 7 and which extends over the entire depth of the drying chamber 1, but ends at a distance from the two side walls 5 which is equal to the width of the rooms 6 is.
- the partition 8 separates from the stack 2 receiving part of the drying chamber 1 a flow channel 9, which is connected at both ends to the rooms 6 and in the exemplary embodiment evenly distributed over the depth of the drying room 1 contains two axial fans 10, which by one vertical axis 10 'are adjustable. One not shown If necessary, the adjustment motor effects the adjustment.
- a heating register 11 is arranged in the longitudinal direction of the flow duct 9 at a distance from the axial fans 10.
- Supply and exhaust air flaps 12 in the upper boundary wall 7 of the drying chamber 1 enable air to enter and exit to reduce the air humidity. Of course, the air can also be conditioned using a dehumidifier.
- adjustable air guiding surfaces 13 are arranged in the two upper corner areas of the drying chamber 1, in which the rooms 6 connect to the two ends of the flow channel 9 and in which the air is deflected by 90 °. These air guiding surfaces 13 have a rectangular shape and are curved in the transverse direction in such a way that they form a channel open towards the interior of the drying chamber 1.
- Each air guide surface 13, which consists for example of an aluminum sheet, is supported by a horizontally arranged axis, to which the longitudinal sides of the air guide surfaces 13 run parallel. The adjustment of the air guiding surfaces 13 about this axis is carried out by means of an electric servomotor 14. As shown in FIG.
- the arrangement of the air guiding surfaces 13 is selected such that they are in the space between the end of the partition 8 and that of the upper boundary wall 7 and the side wall 5 formed corner are arranged and have differently sized distances from the end of the partition 8, which on the side facing the flow channel 9 a flow guide body 15 on its opposite end carries a flowlet body 15 'of the same design.
- Additional air guiding surfaces 16 which each consist of a flat, rectangular sheet metal strip in the exemplary embodiment, are, as shown in FIG. 1, arranged in both rooms 6 at different heights above the floor, with distances from the side wall 5 which increase towards the top.
- These air baffles 16 are each carried by a horizontal shaft, to which the long sides of the air baffles 16 run parallel.
- These rotatably mounted shafts are each coupled to an electric servomotor 17.
- the air guiding surfaces 13 and 16 do not extend over their entire depth because of the great depth of the drying chamber 1. Rather, two identical air guiding surfaces, each with its own servomotor, are arranged side by side in order to be able to influence the air flow differently via the chamber depth.
- Spray nozzles 18 on the side walls 5 of the drying chamber 1 enable the air to be humidified.
- moisture sensors 19 are connected via connecting lines (not shown) to an electronic control circuit 20 which is arranged outside the drying chamber 1 in the exemplary embodiment and from which the entire control takes place. Therefore, not only a converter 21 is connected to the control circuit 20, by means of which the speed of the drive motors of the axial fans 10 can be set continuously and the direction of rotation can be predetermined.
- the control circuit 20 also controls the spray nozzles 18 and the servomotors 14 and 17 as well as the heating register 11 and the motors (not shown) for adjusting the swivel position of the axial fans 10.
- the control circuit 20 determines the optimal air speed of the air flows between the individual sawn timber layers. Accordingly, the position of the air guide surfaces 13 and 16 is predetermined and the speed of the axial fans 10 is determined. On the basis of the measured values supplied by the moisture sensors 19, the air speed is maintained at a predetermined setpoint according to a program, possibly by adjusting the air guide surfaces 13 and / or 16 and changing the speed of the axial fans 10 and / or their swivel position. This program can also include a flow reversal.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
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- Microbiology (AREA)
- Drying Of Solid Materials (AREA)
Abstract
Description
Die Erfindung betrifft ein Verfahren zum Trocknen von Schnittholz, das die Merkmale des Oberbegriffs des Anspruches 1 aufweist, sowie eine Vorrichtung zur Durchführung dises Verfahrens.The invention relates to a method for drying lumber, which has the features of the preamble of claim 1, and an apparatus for performing this method.
Es ist bekannt, für eine Trockenkammer die Luftgeschwindigkeit innerhalb der Holzstapel aus Kammergeometrie, Förderleistung der Ventilatoren, Strömungswiderstand der Heizregister, Größe und Anordnung der Holzstapel, sowie Stapelfaktor näherungsweise zu berechnen und während der Trocknung je nach Holzart, -stärke und -feuchte sowie gewünschter Qualität durch die Ventilatordrehzahl auf geeignete Werte einzustellen. Bei dieser Berechnung bleiben aber eine Reihe von Parametern, beispielsweise die Genauigkeit der Ausstapelung, sogenannte Luftkurzschlüsse, die Oberflächenbeschaffenheit der Hölzer, Veränderungen der Holzlagen durch Schwindung, ungeeignete Stapelleisten und dergleichen außer Betracht, weshalb die Strömungsgeschwindigkeiten zwischen den einzelnen, Schnittholzlagen erheblich vom gewünschten Wert abweichen können. Hinzu kommt, daß mit zunehmender Gesamtstapelhöhe die Unterschiede in der Strömungsgeschwindigkeit der einzelnen zwischen den Holzlagen hindurchtretenden Teilströme stark zunehmen. Dies führt dazu, daß die einzelnen Holzpartien unterschiedlich schnell trocknen. Je nachdem, ob Meßstellen in besser oder in schlechter durchlüfteten Bereichen als regelungsführend für den Trocknungsablauf gewählt werden, kann es Ausschuß durch zu hohe Holzfeuchte, Verfärbungen und Schimmelbildung geben oder durch übertrocknete Ware, wobei mit verlängerter Trocknungszeit auch die Kosten ansteigen. Wenn außerdem, wie vielfach unvermeidbar, Holzchargen mit unterschiedlicher Anfangsfeuchte eingebracht werden, kann es zu zusätzlichen Trocknungsschäden wie Verschalungen, Verwerfungen und Rissen führen, besonders wenn z.B. feuchtere Chargen stärker durchlüftet sind als trockenere,regelungsführende Chargen.It is known for a drying chamber to approximately calculate the air speed within the wood stack from the chamber geometry, the delivery capacity of the fans, the flow resistance of the heating registers, the size and arrangement of the wood stack, and the stacking factor, and during drying, depending on the type of wood, thickness and moisture as well as the desired quality set to suitable values by the fan speed. However, a number of parameters are not taken into account in this calculation, for example the accuracy of the stacking, so-called air short circuits, the surface properties of the wood, changes in the wood layers due to shrinkage, unsuitable stacking strips and the like, which is why the flow velocities between the individual, sawn wood layers deviate significantly from the desired value can. In addition, the total stack height increases the Differences in the flow velocity of the individual partial flows passing through the wood layers increase sharply. This means that the individual parts of the wood dry at different speeds. Depending on whether measuring points in better or poorly ventilated areas are chosen to regulate the drying process, there may be rejects due to excessive wood moisture, discolouration and mold growth or due to over-dried goods, whereby the costs increase with longer drying times. If, in addition, as is often unavoidable, batches of wood with different initial moisture levels are introduced, this can lead to additional drying damage such as shuttering, warping and cracks, especially if, for example, more humid batches are more aerated than drier, regulatory batches.
Der Erfindung liegt daher die Aufgabe zugrunde, ein Trocknungsverfahren zu schaffen, das die beschriebenen Trocknungsmängel vermeidet und darüber hinaus eine Möglichkeit bietet, auch verschiedenartige Hölzer mit Abweichungen in Stärke und/oder Trocknungseigenschaften gleichzeitig in einer Kammer wirtschaftlicher und mit besserer Qualität zu trocknen, als es mit bekannten Verfahren möglich ist. Diese Aufgabe löst ein Verfahren mit den Merkmalen des Anspruches 1.The invention is therefore based on the object of providing a drying process which avoids the drying deficiencies described and moreover offers a possibility of drying different types of wood with deviations in strength and / or drying properties simultaneously in a chamber more economically and with better quality than it is possible with known methods. This object is achieved by a method having the features of claim 1.
Die Luftgeschwindigkeit zwischen den gestapelten Brettern zählt neben Lufttemperatur und -feuchte zu den Parametern, die den Trocknungsfortschritt am stärksten beeinflussen. Es ist deshalb möglich, bei gegebenem Kammerklima Stapelbereiche unterschiedlicher Holzfeuchte, -art und -stärke allein durch Variation der Strömungsgeschwindigkeiten in diesen Bereichen unterschiedlich zu trocknen. Die erforderlichen Strömungsgeschwindigkeiten werden mit Hilfe eines entsprechenden Luftgeschwindigkeitsprofils in der vom Stapel definierten Lufteintrittsebene eingestellt. Dadurch, daß die Strömungsgeschwindigkeit der einzelnen zwischen den Schnittholzlagen hindurchtretenden Luftströme oder zumindest von Gruppen dieser Luftströme in Abhängigkeit von Meßwerten eingestellt wird, welche für den Strömungszustand mittelbar oder un mittelbar kennzeichnend sind, nämlich der Holzfeuchte, des Feuchtegradienten und/oder der Luftgeschwindigkeit, kann man die Abweichung der Strömungsgeschwindigkeit in den von den Schnittholzlagen gebildeten Kanälen vom Sollwert erheblich reduzieren und dadurch entweder eine gleichmäßigere Trocknung erreichen oder die Trocknungszeiten unterschiedlicher Partien aneinander angleichen. Ferner kann man, wenn im Verlauf der Trocknung unzulässige Holzfeuchtedifferenzen auftreten, die eine zu große Endfeuchtestreuung erwarten lassen, die Strömungsgeschwindigkeit korrigieren. Es ist sogar möglich, ständig aufgrund der als Istwert dienenden Meßwerte, einen Istwert/Sollwert-Vergleich durchzuführen und dementsprechend die Strömungsgeschwindigkeit zu regeln. Daher läßt sich mit dem erfindungsgemäßen Verfahren eine gleichmäßige Endfeuchte bei kürzest möglicher Trockenzeit und geringstmöglichem Energieeinsatz erreichen. Vorzugsweise wird das erforderliche Luftgeschwindigkeitsprofil durch eine Änderung der Luftführung vor dem Eintritt der Luft zwischen die Schnittholzlagen eingestellt und verändert, da auf diese Weise auch bei großer Stapelhöhe mit relativ geringem Aufwand eine sehr effektive Beeinflussung der Strömungsgeschwindigkeit zwischen den Holzlagen erreichbar ist. Sofern erforderlich, kann selbstverständlich auch Menge und/oder Druck der Luft vor dem Eintritt zwischen die Schnittholzlagen variiert werden.In addition to air temperature and humidity, the air speed between the stacked boards is one of the parameters that have the greatest influence on the progress of drying. It is therefore possible to dry stack areas of different wood moisture, type and thickness in a given chamber climate simply by varying the flow velocities in these areas. The required flow velocities are set using an appropriate air velocity profile in the air inlet plane defined by the stack. Characterized in that the flow rate of the individual air streams passing through the sawn timber layers or at least of groups of these air streams is set as a function of measured values which are indirect or unrelated to the flow state Indirectly characteristic, namely the wood moisture, the moisture gradient and / or the air speed, the deviation of the flow speed in the channels formed by the sawn timber layers from the target value can be significantly reduced and thereby either achieve a more uniform drying or adjust the drying times of different lots to each other. Furthermore, if inadmissible differences in wood moisture occur during the course of drying, which would lead to an excessive spread of final moisture, the flow rate can be corrected. It is even possible to continuously carry out an actual value / setpoint comparison on the basis of the measured values serving as the actual value and to regulate the flow rate accordingly. Therefore, with the method according to the invention, a uniform final moisture content can be achieved with the shortest possible drying time and the lowest possible use of energy. The required air velocity profile is preferably set and changed by changing the air duct before the air enters between the sawn timber layers, since in this way a very effective influence on the flow velocity between the timber layers can be achieved even with a large stack height. If necessary, the amount and / or pressure of the air can of course also be varied between the layers of lumber before entering.
Um mit möglichst wenigen Meßwerten auszukommen, werden bei einer bevorzugten Ausführungsform die Meßwerte von Holzfeuchte und/oder Luftgeschwindigkeit an Stellen erfaßt, die in unterschiedlicher Höhe über dem Boden des Trocknungsraums liegen. Bei größerer Tiefe des Trocknungsraumes wird es außerdem in der Regel erforderlich sein, die Meßwerte außerdem in unterschiedlichen Tiefen, also in unterschiedlichen horizontalen Abständen senkrecht zur Strömungsrichtung durch den oder die Stapel zu erfassen. Für die Geschwindigkeit einer kontinuierlichen Luftströmung durch die Holzstapel gibt es Grenzwerte, die üblicherweise eingehalten werden, um ein gutes Trocknungsergebnis nicht zu gefährden und eine wirtschaftliche Trocknung zu erreichen.In order to get by with as few measured values as possible, in a preferred embodiment the measured values of wood moisture and / or air speed are recorded at points which lie at different heights above the floor of the drying room. With a greater depth of the drying room, it will generally also be necessary to record the measured values at different depths, that is to say at different horizontal distances perpendicular to the direction of flow through the stack or stacks. There are limit values for the speed of a continuous air flow through the wood piles, which are usually observed in order not to jeopardize a good drying result and to achieve economical drying.
Eine obere Grenze wird neben wirtschaftlichen Gesichtspunkten (Stromkosten, Investitionshöhe) durch Holzart, -stärke, -feuchte und -feuchtegefälle, sowie durch das Kammerklima bestimmt. Eine länger andauernde Überschreitung dieser Grenze kann die gefürchtete Verschalung zur Folge haben, wenn bei raschem Abtrocknen der oberflächennahen Holzschichten das Feuchtegefälle über den Brettquerschnitt (der Feuchtegradient) zu groß wird. Durch eine eingetretene Verschalung wird nicht nur der weitere Trocknungsfortschritt erheblich verlangsamt; es besteht außerdem die Gefahr der Zerstörung des Holzes durch Rißbildung.In addition to economic considerations (electricity costs, investment amount), an upper limit is determined by the type, thickness, moisture and moisture gradient as well as by the chamber climate. The feared formwork may result in this limit being exceeded for a longer period of time if the moisture gradient across the board cross-section (the moisture gradient) becomes too large when the layers of wood near the surface dry quickly. If shuttering has occurred, not only is the further drying progress slowed considerably; there is also a risk of the wood being destroyed by cracking.
Die untere Grenze der kontinuierlichen Luftgeschwindigkeit hängt von der Länge des Luftweges durch die Stapel ab. Bei zu geringer Geschwindigkeit erreicht die Luft bereits vor Stapelaustritt ihr Feuchtegleichgewicht mit der Holzoberfläche, und oberhalb der Fasersättigung (z.B. stets bei sägefrischem Holz) ihre vollständige Sättigung, so daß sie auf dem restlichen Weg durch die Stapel keine weitere Feuchte aus dem Holz aufnehmen kann. Als Folge stellt sich im Verlauf der Trocknung ein ansteigendes Holzfeuchteprofil längs des Luftweges durch die Stapel ein, bei Reversierbetrieb symmetrisch zur Stapelmitte.The lower limit of the continuous air speed depends on the length of the airway through the stacks. If the speed is too low, the air will reach its moisture equilibrium with the wood surface before the stack exits, and above the fiber saturation (e.g. always with freshly sawn wood) its full saturation, so that it cannot absorb any more moisture from the wood the rest of the way through the stack. As a result, an increasing wood moisture profile occurs along the airway through the stacks in the course of drying, in the case of reversing operation symmetrically to the center of the stack.
Dieser unerwünschte Effekt macht es besonders bei großen Trockenkammern mit langem Luftweg durch die Stapel erforderlich, die Stapel mit einer höheren, kostensteigernden Strömungsgeschwindigkeit zu versorgen, als es für den gewünschten wirtschaftlichen Trocknungsfortschritt an sich notwendig wäre. Inbesondere wird diese hohe Luftgeschwindigkeit nur in dem Trocknungsabschnitt oberhalb des Fasersättigungsbereichs benötigt, so daß bei darunterliegenden Holzfeuchten unnötige elektrische Energie aufgrund der dafür überdimensionierten Ventilatorleistung verschwendet würde. Dieser Diskrepanz versucht man heute durch Einsatz polumschaltbarer Motore oder Verwendung von Frequenzumrichtern zu begegnen. Neben anderen Nachteilen bleiben aber hohe Investitionskosten, die sich noch weiter dadurch erhöhen können, daß aufgrund der erforderlichen sehr hohen Ventilatorleistung am Anfang der Trocknung der Ventilatorraum entsprechend größer gebaut werdn muß, um die erforderliche Ventilatorenzahl überhaupt installieren zu können.This undesirable effect makes it necessary, especially in the case of large drying chambers with a long air path through the stacks, to supply the stacks with a higher, cost-increasing flow rate than would be necessary for the desired economical drying progress per se. In particular, this high air speed is only required in the drying section above the fiber saturation area, so that unnecessary electrical energy would be wasted due to the oversized fan power for wood moisture underneath. This discrepancy is being attempted today by using pole-changing motors or using frequency converters. In addition to other disadvantages, however, there remain high investment costs which can be increased further by the very high fan output required at the beginning of the drying process, the fan room must be built larger in order to be able to install the required number of fans at all.
Diese Nachteile lassen sich ebenfalls mit den Merkmalen des Anspruches 1 vermeiden, ohne die Trocknungs- und Investitionskosten durch zu hohe Ventilatorleistung zu steigern.These disadvantages can also be avoided with the features of claim 1 without increasing the drying and investment costs due to excessive fan performance.
Ein konzentrierter Luftstrom mit hoher Geschwindigkeit wird nacheinander auf alle Bereiche des Stapeleintritts gerichtet. Dabei wird die Konzentrierung durch eine geeignete Stellung der Ventilatoren und/oder Luftlenkeinrichtungen erreicht. Da bei hoher Geschwindigkeit die Verweildauer bestimmter Luftvolumina innerhalb der Stapel nur gering ist, können sie nicht in die Nähe des Feuchtigkeitsgleichgewichtes mit dem Holz bzw. ihrer Sättigungsfeuchte gelangen. Eine Verschalung kann wegen des relativ trägen Feuchtetransportes von Holz nicht eintreten, wenn die Phasen hoher Geschwindigkeit nicht zu lange andauern. Der für den Trocknungsfortschritt entscheidende zeitliche Mittelwert der Luftgeschwindigkeit läßt sich problemlos dadurch absenken, daß die Dauer der Phasen hoher Geschwindigkeit für einzelne Stapelbereiche klein genug gegenüber der Dauer niedriger Geschwindigkeit gewählt wird.A high speed, concentrated air stream is sequentially directed to all areas of the stack entrance. The concentration is achieved by a suitable position of the fans and / or air steering devices. Since at high speed the dwell time of certain air volumes within the stack is only short, they cannot get close to the moisture balance with the wood or its saturation moisture. Due to the relatively sluggish moisture transport of wood, shuttering cannot occur if the phases of high speed do not last too long. The temporal mean value of the air speed, which is decisive for the drying progress, can easily be reduced by selecting the duration of the high speed phases for individual stacking areas to be small enough compared to the duration of the low speed.
Bei hinreichend hoher Konzentrierung des Gesamtluftstroms kann sogar auf Luftrichtungsumkehr verzichtet werden, wodurch sich Luftlenkeinrichtungen an einem der beiden Stapelenden erübrigen und die gesamte Trocknungsregelung vereinfacht wird.With a sufficiently high concentration of the total air flow, it is even possible to do without a reversal of the air direction, as a result of which there is no need for air-directing devices on one of the two stack ends and the overall drying control is simplified.
Damit auch mit diesem Verfahren unterschiedliche Holzchargen gleichzeitig in einer Kammer wirtschaftlich getrocknet werden können, wird gemäß Anspruch 5 die Dauer, während der ein bestimmter Stapelbereich dem konzentrierten Luftstrom ausgesetzt wird, in Abhängigkeit von Feuchte und/oder Feuchtegradient des Holzes in diesem Bereich variiert.So that different wood batches can be dried economically in one chamber at the same time with this method, the duration during which a particular stacking area is exposed to the concentrated air flow is varied depending on the moisture and / or moisture gradient of the wood in this area.
Der Erfindung liegt ferner die Aufgabe zugrunde, eine Trocknungsvorrichtung zur Durchführung des erfindungsgemäßen Verfahrens zu schaffen. Diese Aufgabe löst eine Trockungsvorrichtung mit den Merkmalen des Anspruches 5.The invention is also based on the object of providing a drying device for carrying out the method according to the invention. This object is achieved by a drying device with the features of
Bei einer bevorzugten Ausführungsform weist die Strömungslenkeinrichtung verstellbare Luftleitflächen auf, weil mittels solcher Luftleitflächen in einfacher Weise den verschiedenen Teilen der Stapel oder den unterschiedlichen Holzpartien die erforderlichen Luftmengen abhängig davon zugeführt werden können, wie groß die übrigen Luftmengen sind. Zwar kann man zumindest dann, wenn die Stellung des Ventilators oder der Ventilatoren die Luftverteilung auf die einzelnen Spalte zwischen den Holzlagen beeinflußt, auch durch eine Verstellung, beispielsweise Verschwenkung, der Ventilatoren zu einer Beeinflussung der Geschwindigkeit der einzelnen Luftströme kommen. In der Regel wird jedoch eine Verstellbarkeit der Ventilatoren nur in Verbindung mit Luftleitflächen ausreichend sein.In a preferred embodiment, the flow directing device has adjustable air guide surfaces, because by means of such air guide surfaces the required air quantities can be supplied to the different parts of the stack or the different wood parts in a simple manner depending on how large the other air quantities are. It is true that at least when the position of the fan or fans influences the air distribution to the individual gaps between the wooden layers, the fans can also be adjusted, for example by pivoting, to influence the speed of the individual air streams. As a rule, however, adjustability of the fans will only be sufficient in connection with air guiding surfaces.
Die Luftleitflächen und, falls verstellbar, die Ventilatoren, können einen manuellen Antrieb aufweisen. Vorzugsweise sind jedoch Stellmotoren vorgesehen, um die Verstellung über eine Steuereinrichtung oder eine Regeleinrichtung ausführen zu können.The air guiding surfaces and, if adjustable, the fans can have a manual drive. However, servomotors are preferably provided in order to be able to carry out the adjustment via a control device or a regulating device.
Ist, wie vielfach der Fall, oberhalb des das Schnittholz aufnehmenden Teils des Trockenraumes ein horizontaler Strömungskanal vorgesehen, in dem sich der Ventilator oder die Ventilatoren befinden,dann sind vorteilhalterweise an wenigstens einem der beiden Enden dieses Strömungskanals die als Umlenkelemente ausgebildeten Luftleitflächen angeordnet. Es kann dann mit ihrer Hilfe die Umlenkung so erfolgen, daß die Eintrittsöffnungen der zwischen den Holzlagen vorhandenen Zwischenräume mit den erforderlichen Luftströmen beaufschlagt werden.If, as is often the case, a horizontal flow channel is provided above the part of the drying room that receives the sawn timber, in which the fan or fans are located, then the air guiding surfaces designed as deflection elements are advantageously arranged on at least one of the two ends of this flow channel. With their help, the deflection can then take place in such a way that the required air streams are applied to the inlet openings of the spaces between the wooden layers.
Zusätzlich zu diesen Luftleitflächen und vor allem dann, wenn diese nicht verstellbar sind, kann man als Umlenkelemente ausgebildete Luftleitflächen in unterschiedlichen Höhen auf der Luftein- und austrittsseite der Schnittholzstapel vorsehen. Diese Umlenkelemente können sowohl um eine horizontale Achse schwenkbar als auch in vertikaler Richtung verstellbar in einer Halterung angeordnet sein. Man kann dann die gesamte Stapelhöhe gewissermaßen in mehrere Abschnitte unterteilen, innerhalb deren die Luftströme unabhängig voneinander eingestellt oder geregelt werden können. Es kann deshalb wünschenswert sein, die Umlenkelemente auch unabhängig voneinander einstellen und positionieren zu können. Diese Positionen können beispielsweise in Abhängigkeit von den Holzfeuchten und den davon abgeleiteten Holzfeuchtedifferenzen unter Berücksichtigung der Höhenpositionen der einzelnen Meßstellen mittels eines Prozessrechners erfaßt und in die erforderlichen Steuerbefehle umgesetzt werden. Dabei können beispielsweise Rückführpotentiometer an den Stellmotoren die momentane Position erfassen. Die Strömungslenkung kann dabei auch so gewählt werden, daß Stapelteile zumindest teilweise überhaupt nicht mehr mit der zirkulierenden Umluft versorgt werden.In addition to these air guiding surfaces and especially if they are not adjustable, air guiding surfaces designed as deflection elements can be provided at different heights on the air inlet and outlet sides of the lumber stack. These deflection elements can be arranged in a holder both pivotable about a horizontal axis and adjustable in the vertical direction. One can then sort of divide the entire stack height into several sections, within which the air flows can be adjusted or regulated independently of one another. It may therefore be desirable to be able to adjust and position the deflection elements independently of one another. These positions can be determined, for example, as a function of the wood moisture and the wood moisture differences derived therefrom, taking into account the height positions of the individual measuring points, by means of a process computer and converted into the necessary control commands. For example, feedback potentiometers on the servomotors can record the current position. The flow control can also be selected so that stack parts are at least partially no longer supplied with the circulating air.
Außer der Beeinflussung der Strömungsgeschwindigkeit in den in vertikaler Richtung übereinander liegenden Strömungskanälen kann es wünschenswert oder notwendig sein, die Luftverteilung quer zur Strömungsrichtung in den Strömungskanälen, also in Richtung der Kammertiefe, zu beeinflussen, um Holzfeuchtedifferenzen in Kammertiefe auszugleichen oder in Kammertiefe nebeneinander angeordnete Stapel unterschiedlich mit Luft zu beaufschlagen. Hierzu brauchen nur wenigstens zwei der genannten Umlenkelemente in Richtung der Kammertiefe nebeneinander angeordnet zu sein, um auf die Luftströmung einwirken zu können. Ein weitere Lösung ist die Verstellbarkeit der vor dem Stapeleintritt liegenden Umlenkelemente um eine senkrechte oder um zwei unterschiedliche Drehrichtungen, vorzugsweise senkrecht zueinanderIn addition to influencing the flow velocity in the flow channels lying one above the other in the vertical direction, it may be desirable or necessary to influence the air distribution transversely to the flow direction in the flow channels, i.e. in the direction of the chamber depth, in order to compensate for wood moisture differences in the chamber depth or stacks arranged next to one another in the chamber depth to apply air. For this purpose, only at least two of the deflection elements mentioned need to be arranged next to one another in the direction of the chamber depth in order to be able to act on the air flow. Another solution is the adjustability of the deflection elements located in front of the stack entrance by a vertical or by two different directions of rotation, preferably perpendicular to one another
Wenn die Ventilatoren in einem durch eine Zwischendecke abgetrennten Kanal oberhalb der Holzstapel angeordnet sind, ist vorzugsweise jeder Ventilator abhängig von den anderen um eine vertikale Achse verstellbar, damit bei geeigneter Drehung die Luftströmungen auf einen oder mehrere Bereiche längs der Kammertiefe gerichtet werden können. Sofern maximale Drehwinkel von mehr als 180° (z.B. 270°) gewählt werden, läßt sich zusätzlich eine Umkehrung der Luftrichtung auch mit solchen Ventilatoren erreichen, die nur für eine Drehrichtung ausgelegt sind und dadurch einem um ca. 1 - 20 % höheren Wirkungsgrad aufweisen als reversierbare Ventilatoren.If the fans are arranged in a channel separated by a false ceiling above the wood piles, each fan is preferably adjustable about a vertical axis depending on the others, so that the air flows can be directed to one or more areas along the chamber depth with a suitable rotation. If maximum rotation angles of more than 180 ° (eg 270 °) are selected, a reversal of the air direction can also be achieved with fans that are only designed for one direction of rotation and are therefore about 1 - 20% more efficient than reversible fans.
Wenn der oder die Ventilatoren seitlich neben dem Holzstapel angeordnet ist/sind, also bei mindestens zwei Ventilatoren diese übereinander angeordnet sind, ist vorzugsweise jeder Ventilator unabhängig von den anderen um eine horizontale Achse verstellbar, um bei geeigneter Positionierung die Luftströmungen auf auswählbare horizontale Holzlagen zu richten.If the fan or fans is / are arranged laterally next to the wood stack, i.e. if at least two fans are arranged one above the other, each fan can preferably be adjusted independently of the others about a horizontal axis in order to direct the air flows onto selectable horizontal wood layers when suitably positioned .
Ist eine Umkehr der Strömungsrichtung vorgesehen, kann man auch durch unterschiedlich lange Reversierzeiten einen Holzfeuchteausgleich bei abweichenden Holzfeuchten im Bereich des Lufteintritts und des Luftaustritts der durch die Holzlagen gebildeten Kanäle erreichen. Im Falle der Umkehrbarkeit der Strömungsrichtung sind Luftleitflächen auf beiden Seiten des Trocknungsraumes zweckmäßig.If a reversal of the flow direction is provided, wood moisture compensation can also be achieved with different wood moisture levels in the area of the air inlet and the air outlet of the channels formed by the wood layers by reversing times of different lengths. In the case of reversibility of the flow direction, air guiding surfaces on both sides of the drying room are advisable.
Im folgenden ist die Erfindung anhand eines in der Zeichnung dargestellten Ausführungbeispiels im einzelnen erläutert.The invention is explained in detail below using an exemplary embodiment shown in the drawing.
Es zeigen
- Fig. 1 einen schematisch dargestellten Querschnitt des Ausführungsbeispiels,
- Fig. 2 einen schematisch und unvollständig dargestellten Längsschnitt.
- 1 shows a schematically illustrated cross section of the exemplary embodiment,
- Fig. 2 shows a schematic and incomplete longitudinal section.
In einer Trocknungskammer 1 zur Aufnahme wenigstens eines Holzstapels 2, der aus dem zu trocknenden Schnittholz 3 und den zwischen zwei benachbarten Schnittholzlagen angeordneten Stapelleisten besteht, hat im Ausführungsbeispiel eine kubische Form und ist an einer Stirnseite mit einem nicht dargestellten Tor versehen, das während der Trocknungsvorganges die Trocknungskammer 1 dicht verschließt. Die Holzstapel 2 werden so im Trocknungsraum 1 nebeneinander und ggf. hintereinander angeordnet, daß sich die Stapelleisten 4 in Querrichtung der Trocknungskammer 1 erstrecken und zwischen den beiden Seitenwänden 5 der Trocknungskammer und den Holzstapeln 2 ein ausreichend breiter Raum 6 freibleibt.In a drying chamber 1 for receiving at least one
Im Abstand unterhalb der oberen Begrenzungswand 7 der Trocknungskammer 1 ist eine zur obere Begrenzungswand 7 parallel verlaufende Trennwand 8 angeordnet, welche sich über die gesamte Tiefe der Trocknungskammer 1 erstreckt, jedoch in einem Abstand von den beiden Seitenwänden 5 endet, welcher gleich der Breite der Räume 6 ist. Die Trennwand 8 trennt von dem die Stapel 2 aufnehmenden Teil der Trocknungskammer 1 einen Strömungskanal 9 ab, der an seinen beiden Enden mit den Räumen 6 in Verbindung steht und im Ausführungsbeispiel gleichmäßig über die Tiefe des Trockenraumes 1 verteilt zwei Axialventilatoren 10 enthält, die um eine vertikale Achse 10′ verstellbar sind. Je ein nicht dargestellter Verstellmotor bewirkt im Bedarfsfalle die Verstellung. In Längsrichtung des Strömungskanals 9 im Abstand von den Axialventilatoren 10 ist ein Heizregister 11 angeordnet. Zuluft- und Abluftklappen 12 in der oberen Begrenzungswand 7 der Trocknungskammer 1 ermöglichen einen Luftaus- und -eintritt zur Verminderung der Luftfeuchtigkeit. Selbstverständlich kann die Luft auch mittels einer Entfeuchtungsvorrichtung konditioniert werden.At a distance below the
In den beiden oberen Eckbereichen der Trocknungskammer 1, in denen die Räume 6 an die beiden Enden des Strömungskanals 9 anschließen und in denen die Luft eine Umlenkung um 90° erfährt, sind verstellbare Luftleitflächen 13 angeordnet. Diese Luftleitflächen 13 haben eine rechteckförmige Form und sind in Querrichtung derart gekrümmt, daß sie eine gegen das Innere der Trocknungskammer 1 hin offene Rinne bilden. Jede Luftleitfläche 13, die beispielsweise aus einem Aluminiumblech besteht, wird von einer horizontal angeordneten Achse getragen, zu der die Längsseiten der Luftleitflächen 13 parallel verlaufen. Die Verstellung der Luftleitflächen 13 um diese Achse erfolgt mittels je eines elektrischen Stellmotors 14. Wie Fig. 1 zeigt, ist die Anordnung der Luftleitflächen 13 so gewählt, daß sie in dem Raum zwischen dem Ende der Trennwand 8 und der von der oberen Begrenzungswand 7 und der Seitenwand 5 gebildeten Ecke angeordnet sind und unterschiedlich große Abstände von dem Ende der Trennwand 8 haben, das auf der dem Strömungskanal 9 zugekehrten Seite einen Strömungsleitkörper 15 auf seinem entgegengesetzten Ende einen gleich ausgebildeten Strömungsletkörper 15′ trägt.In the two upper corner areas of the drying chamber 1, in which the rooms 6 connect to the two ends of the
Zusätzliche Luftleitflächen 16, welche im Ausführungsbeispiel je aus einem ebenen, rechteckförmigen Blechstreifen bestehen, sind, wie Fig. 1 zeigt, in beiden Räumen 6 in unterschiedlicher Höhe über dem Boden angeordnet und zwar mit Abständen von der Seitenwand 5, die nach oben hin zunehmen. Auch diese Luftleitbelche 16 werden von je einer horizontalen Welle getragen, zu der die Längsseiten der Luftleitflächen 16 parallel verlaufen. Diese drehbar gelagerten Wellen sind ebenfalls mit je einem elektrischen Stellmotor 17 gekoppelt.Additional air guiding surfaces 16, which each consist of a flat, rectangular sheet metal strip in the exemplary embodiment, are, as shown in FIG. 1, arranged in both rooms 6 at different heights above the floor, with distances from the
Wie Fig. 2 zeigt, erstrecken sich im Ausführungsbeispiel die Luftleitflächen 13 und 16 wegen der großen Tiefe der Trocknungskammer 1 nicht über deren gesamte Tiefe. Vielmehr sind jeweils zwei gleich ausgebildete Luftleitflächen, die je einen eigenen Stellmotor haben, nebeneinander angeordnet, um über die Kammertiefe die Luftströmung unterschiedlich beeinflussen zu können.As shown in FIG. 2, in the exemplary embodiment the air guiding surfaces 13 and 16 do not extend over their entire depth because of the great depth of the drying chamber 1. Rather, two identical air guiding surfaces, each with its own servomotor, are arranged side by side in order to be able to influence the air flow differently via the chamber depth.
Sprühdüsen 18 an den Seitenwänden 5 der Trocknungskammer 1 ermöglichen eine Befeuchtung der Luft.Spray
In unterschiedlichen Höhen der Holzstapel 2 werden einzelne Holzlagen mit einem Feuchtesensor 19 versehen, der ein analoges Meßsignal liefert. Diese Feuchtesensoren 19 sind über nicht dargestellte Verbindungsleitungen mit einer im Ausführungsbeispiel außerhalb der Trocknungskammer 1 angeordneten elektronischen Steuerschaltung 20 verbunden, von welcher aus die gesamte Steuerung erfolgt. Daher ist an die Steuerschaltung 20 nicht nur ein Umrichter 21 angeschlossen, mittels dessen die Drehzahl der Antriebsmotoren der Axialventilatoren 10 stufenlos eingestellt und die Drehrichtung vorgegeben werden kann. Von der Steuerschaltung 20 aus erfolgt auch die Steuerung der Sprühdüsen 18 und der Stellmotoren 14 und 17 sowie die Steuerung des Heizregisters 11 und der nicht dargestellten Motoren zur Einstellung der Schwenklage der Axialventilatoren 10.At different heights of the
Aufgrund der Daten über das Schnittholz 3, das zur Trocknung in den Trockenraum 1 eingebracht wird, bestimmt die Steuerschaltung 20 die optimale Luftgeschwindigkeit der Luftströme zwischen den einzelnen Schnittholzlagen. Dementsprechend wird die Stellung der Luftleitflächen 13 und 16 vorgegeben sowie die Drehzahl der Axialventilatoren 10 bestimmt. Aufgrund der von den Feuchtesensoren 19 gelieferten Meßwerte wird die Luftgeschwindigkeit, ggf. durch eine Verstellung der Luftleitflächen 13 und/oder 16 und eine Änderung der Drehzahl der Axialventilatoren 10 und/oder deren Schwenklage, entsprechend einem Programm auf einem vorgegebenen Sollwert gehalten. Dieses Programm kann auch eine Umkehrung der Strömungsrichtung beinhalten.On the basis of the data about the sawn
Alle in der vorstehenden Beschreibung erwähnten sowie auch die nur allein aus der Zeichnung entnehmbaren Merkmale sind als weitere Ausgestaltungen Bestandteile der Erfindung, auch wenn sie nicht besonders hervorgehoben und insbesondere nicht in den Ansprüchen erwähnt sind.All of the features mentioned in the above description and also the features that can only be inferred from the drawing are further refinements of the invention, even if they are not particularly emphasized and in particular are not mentioned in the claims.
Claims (11)
Priority Applications (1)
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AT88106746T ATE91776T1 (en) | 1987-05-26 | 1988-04-27 | DEVICE FOR DRYING LUMBER. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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DE19873717659 DE3717659A1 (en) | 1987-05-26 | 1987-05-26 | METHOD AND DEVICE FOR DRYING WOOD |
DE3717659 | 1987-05-26 |
Publications (3)
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EP0292717A2 true EP0292717A2 (en) | 1988-11-30 |
EP0292717A3 EP0292717A3 (en) | 1991-04-17 |
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EP19880106746 Revoked EP0292717B1 (en) | 1987-05-26 | 1988-04-27 | Timber drying device |
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US (1) | US4862599A (en) |
EP (1) | EP0292717B1 (en) |
AT (1) | ATE91776T1 (en) |
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DE (2) | DE3717659A1 (en) |
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FR2805769A1 (en) * | 2000-03-01 | 2001-09-07 | Realisation De Travaux Electr | WOOD DRYING PROCESS AND DEVICE FOR IMPLEMENTING SAME |
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DE3340489A1 (en) * | 1983-11-09 | 1985-08-14 | Lignomat GmbH, 7148 Remseck | METHOD FOR DRYING WOOD |
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1987
- 1987-05-26 DE DE19873717659 patent/DE3717659A1/en active Granted
-
1988
- 1988-04-27 AT AT88106746T patent/ATE91776T1/en active
- 1988-04-27 ES ES198888106746T patent/ES2041729T3/en not_active Expired - Lifetime
- 1988-04-27 DE DE8888106746T patent/DE3882436D1/en not_active Revoked
- 1988-04-27 EP EP19880106746 patent/EP0292717B1/en not_active Revoked
- 1988-05-19 US US07/195,818 patent/US4862599A/en not_active Expired - Fee Related
- 1988-05-25 CA CA000567581A patent/CA1337153C/en not_active Expired - Fee Related
Patent Citations (1)
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US3386186A (en) | 1965-02-02 | 1968-06-04 | Robert Hildebrand Maschb G M B | Apparatus for conducting a gaseous drying medium |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GR900100018A (en) * | 1990-01-16 | 1992-06-25 | Mihalis Tsamparlis | Fruit and vegetable drying plant |
FR2660424A1 (en) * | 1990-04-03 | 1991-10-04 | Electricite De France | Method and installation for drying damp solid wood with a high throughput |
FR2805769A1 (en) * | 2000-03-01 | 2001-09-07 | Realisation De Travaux Electr | WOOD DRYING PROCESS AND DEVICE FOR IMPLEMENTING SAME |
EP1132704A1 (en) * | 2000-03-01 | 2001-09-12 | Societe d'etudes et Realisations de Travaux Electriques Sertelec S.A. | Process for drying wood and apparatus for carrying out this process |
Also Published As
Publication number | Publication date |
---|---|
EP0292717A3 (en) | 1991-04-17 |
US4862599A (en) | 1989-09-05 |
DE3717659C2 (en) | 1990-03-08 |
EP0292717B1 (en) | 1993-07-21 |
DE3717659A1 (en) | 1988-12-15 |
ATE91776T1 (en) | 1993-08-15 |
ES2041729T3 (en) | 1993-12-01 |
DE3882436D1 (en) | 1993-08-26 |
CA1337153C (en) | 1995-10-03 |
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