EP2966389A1 - Drying device - Google Patents

Abstract

A drying device 2 for drying stacked wood 8, which has a stacking space 4 for receiving the stacking wood 8 and flow-through means 10 for the flow of the stacking wood 8 with drying air or another drying medium. To enter the drying medium in the stacking space 8, an inlet opening 26 is provided in a stack entrance level. According to the invention, at least one flow blocking element 30 is provided, which is movable to change the shape and / or the cross section of the inlet opening 26 in the stack entry plane.

Description

The invention relates to a drying device referred to in the preamble of claim 1 for the drying of stacked wood.

Such drying devices are well known and are used for example and in particular for drying sawn timber.

By EP 0 292 717 B1 a drying device of the type in question for drying of stacking wood is known, which has a stacking space for receiving the stacking wood and flow medium for flow of the stacked wood with drying air or other drying medium, wherein an inlet opening is provided for entry of the drying medium in the stacking space in a Stapeleintrittsebene.

By EP 0 142 071 B1 a method for drying of stack wood is known, in which the stack wood is impulsively or intermittently flowed with the drying medium.

The invention has for its object to provide a drying device referred to in the preamble of claim 1 species, which is energy-efficient operable and ensures a good drying quality of the stack wood.

This object is achieved by the specified in claim 1 Invention solved.

• Es ist bekannt, dass bei der Trocknung beispielsweise von Schnittholz die Strömungsgeschwindigkeit des Trocknungsmediums zwischen den Brettlagen des Stapelholzes die Trocknungsgeschwindigkeit mitbestimmt. Ist die Strömungseschwindigkeit des Trocknungsmediums zu niedrig, so trocknet das Stapelholz zu langsam, wobei es darüber hinaus zu einer Beeinträchtigung der Trocknungsqualität kommen kann, indem sich beispielsweise ungleichmäßige Feuchtigkeitsverteilungen des Stapelholzes ergeben oder das Stapelholz beginnt zu schimmeln. Ist dem gegenüber die Geschwindigkeit des Trocknungsmediums zu hoch, so können an dem Stapelholz durch zu große Spannungen im Holz eine Verschalung und möglicherweise Rissbildung auftreten. Außerdem ergibt sich ein zu hoher Verbrauch an elektrischer Energie für das Betreiben von beispielsweise Umluftventilatoren.

The invention is based on the following findings:

• It is known that during drying of, for example, sawn timber, the flow rate of the drying medium between the board layers of the stacked wood determines the drying rate. If the flow rate of the drying medium is too low, the stack wood dries too slowly, which can also affect the drying quality, for example, resulting in uneven moisture distributions of the stacked wood or the stack wood begins to mold. If, on the other hand, the speed of the drying medium is too high, overfilling and possibly cracking can occur on the stacked wood as a result of excessive stresses in the wood. In addition, there is an excessive consumption of electrical energy for the operation of, for example circulating air fans.

It is known in this connection to vary the flow rate of the drying medium, for example by using frequency converters for controlling circulating air fans, which are part of the flow means.

On this basis, the invention is based on the finding that with a reduction in the flow rate of the drying medium from a maximum flow rate to zero or near zero and back to a maximum flow rate no extension of the drying time occurs due to the at least temporary lowering of the flow rate to zero or near zero At the same time, however, the power consumption of circulating air fans is reduced. As a result, the Drying process continues, even if the flow rate of the drying medium and thus the supply of heat to the surface of the stack wood is temporarily reduced to zero or near zero. In particular, the moisture content of the surface layers of the stacked wood is strongly and directly influenced by the prevailing flow velocity of the drying medium. If this flow rate is zero or near zero, so there is virtually no moisture removed and no more heat supplied, so that the drying of the outermost layers of the stack wood stagnates. Nevertheless, moisture transport continues to occur due to water vapor diffusion / temperature gradient from the inner layers of the stacked wood to the outer ones. This water vapor diffusion results in "driving forces" that provide moisture transport from the inner layers of the stacked wood to the outer layers and to the surface.

If, after a phase in which the flow rate of the drying medium at the surface of the stacked wood was zero or near zero and moisture has been transported from the inner layers to the surface of the stacked wood in the manner described, the flow rate of the drying medium is increased again, Thus, the moisture accumulated on the surface and / or in the near-surface layers can be removed easily and quickly. It has been shown that when changing the flow velocity in the manner described and in coordination with this change, an increase / decrease in the setpoints for temperature and humidity not only does not increase the total drying time, but the entire Drying process can be performed faster and gentler.

Based on this, the invention is based on the idea that the drying process in the sense of a high and constant drying quality on the one hand and the lowest possible consumption of electrical energy on the other hand can be positively influenced if the flow rate of the drying medium flowing around the stacked wood within the stacking space during the drying process is varied such that the flow rate in the stack space is partially reduced to zero or near zero and subsequently increased again.

On this basis, the invention provides at least one flow blocking element that is movable to change the shape and / or the cross section of the inlet opening in the stack entry plane.

The basic idea of the invention is to influence the flow of the drying medium directly in front of the plane of entry of the drying medium into the stacking wood (stack entrance level). This results along the surface of the inlet opening areas which are blocked by the flow blocking element and in which the material to be dried (stacked wood) is thus not flowed, and areas which are released for an entry of the drying medium in the stack and in which the stack wood thus with the drying medium is flowed. The flow blocking element thus forms a flow bulkhead, by means of which, along the entry plane, areas of the stacked wood can be sealed off against the flow of the drying medium, while other areas are released for entry of the drying medium into the stacks.

In other words, the flow blocking element divides the area of the inlet opening into a region which is covered by the flow blocking element, so that in the region of the stacks downstream of the drying medium in the direction of flow of the drying medium, the flow rate of the drying medium is zero or close to zero and a region suitable for one Admission of the drying medium is released into the stack and in which the flow rate of the drying medium according to the respective power of the flow medium is greater than zero. In areas which are sealed off by the flow blocking element, the stacked wood in the stacking space is thus not flown, wherein the drying process in the manner already described above proceeds further by transporting moisture from the interior of the stacked wood to the surface thereof.

Since the flow blocking element is movable, according to the invention, different regions of the stacking space can be sequentially timed off against the flow of the drying medium and subsequently exposed again to the flow of the drying medium.

It has been shown that a drying process is realized by means of the drying device according to the invention, which not only runs particularly smoothly and quickly, but is also particularly energy-efficient.

Since the flow blocking element reduces the effective cross section of the inlet opening, a higher flow velocity can be realized in the unseeded stack area with the same fan power of the circulating air fans used, or it can at a given flow rate Fan speed of the circulating fans or their number and thus their consumption of electrical energy can be reduced.

The invention has a high social benefit, in that the drying process of hygroscopic goods, in particular of wood, which in principle requires a high expenditure of energy, can be made substantially more energy-efficient. For example, a drying process with constant drying quality using the device according to the invention may require up to 25 percent less energy. In this way, CO2 emissions, which threaten the climate, are substantially reduced.

An advantageous development of the invention provides that the flow device is reversible. This means that the flow direction along which the drying medium flows in the direction of the stacked wood is reversible. By reversing and / or pulse / pause timing of the flow device and changing the position of the flow blocking elements can be prevented in particular that form undesirable laminar flows of the drying medium. Rather, the formation of turbulent flows is promoted by reversing and / or pulse / pause clocking and changing the position of the flow blocking elements.

For example, and in particular, the flow means may comprise at least one recirculation fan, which may be assigned to control its speed and / or direction of rotation, in particular at least one frequency converter.

An extraordinarily advantageous development of an embodiment of the invention, in which the outlet of the drying medium for a longer distance from the Stack is provided in a Stapelaustrittsebene an outlet opening, provides at least one flow blocking element, which is movable to change the shape and / or the cross section of the outlet opening in the Stapelaustrittsebene. In this way, the function according to the invention of a flow blocking element is maintained even when the flow direction is reversed, that is to say when the direction of the flow of the drying medium through the stack space is reversed.

If at least one flow blocking element is provided both in the stack entry plane and in the stack exit plane, then they are synchronously moved with one another in such a way that they are always aligned with one another in the flow direction. In this way it is ensured that certain areas of the stack wood are sealed off in the desired manner against the flow of the drying medium.

According to the respective requirements, the flow blocking element may be formed in any suitable manner. In that regard, an advantageous development of the invention provides that the flow blocking element is formed areally and is movable along the stack entry plane or the stack exit plane. By way of example and in particular, the flow blocking element can be designed in the manner of a shielding plate, which is movable by means of a suitable drive along the cross section of the stack entry plane. By appropriate choice of the material and configuration of the flow blocking element, the same can be designed particularly lightweight, so that only a small drive power is required to move the flow blocking element.

An advantageous development of the aforementioned Embodiment provides that at least one flow blocking element along at least one axis is horizontally and / or vertically movable. In this embodiment, the flow blocking element can, for example, be moved along the vertical axis, that is to say along the height extent of the stacks, so that temporally successive different height regions of the stacks are sealed off against the flow of the drying medium. However, according to the invention it is also possible for at least one flow blocking element to be movable along the width dimension of the stacks, that is to say in the horizontal direction, so that along the width extent of the stacks time-sequentially different regions are sealed off against entry of the drying medium. It is also possible for at least one flow blocking element to move linearly along two axes.

Another development of the invention provides that at least one flow blocking element is assigned a drive device. The or each drive device may, for example, have an electromotive drive and be configured in a variety of ways according to the respective requirements. If the flow blocking element is linearly movable along at least one axis, the drive device is expediently designed as a linear drive.

A development of the abovementioned embodiment provides a control device for controlling the drive device. The control device controls the drive device of the flow blocking element in such a way that the flow blocking element is in the desired position during the drying process, and thus in each case a desired one Area of the stack is sealed off against a flow of the drying medium.

An advantageous development of the embodiment with the control device provides that the control device controls the drive device during the drying process time-controlled. In this embodiment, the flow blocking element is thus moved during the drying process in accordance with a predetermined time cycle. The timing can be set before the start of the drying process, in particular using the parameters of the wood to be dried (type of wood, board thickness, initial moisture content, etc.). However, it is also possible according to the invention to move at least one flow blocking element as a function of at least one drying parameter sensed during the drying process, in particular the moisture content of the wood, the humidity, the temperature or the flow rate of the drying medium.

An advantageous development of the invention thus provides at least one sensor for sensing at least one drying parameter in the stacks, wherein the control device is designed and set up to control at least one flow blocking element as a function of output signals of the sensor. In this embodiment, drying parameters within the stack are sensed by means of a sensor, and the drive device of the flow blocking element is controlled by the control device such that the flow blocking element is in a desired or required location, corresponding to the actual process of the drying process. In this way, so targeted areas of the stack at certain times of the drying process are sealed off from the flow of the drying medium, if it is desirable or necessary that in this area the drying process proceeds without flow of the drying medium.

In order to enable spatially resolved detection of the drying climate in the drying chamber, an advantageous development of the invention provides at least two sensors spaced apart from each other for sensing at least one drying parameter. In this way it can be determined with greater accuracy how far the drying process has progressed in the different spatial areas of the stacks and thus, for example, in different stacks of the stacked wood.

Another advantageous development of the invention provides at least two preferably independently movable flow blocking elements. Shape, size and number of flow blocking elements can be selected according to the respective requirements within wide limits.

Another advantageous embodiment of the invention provides that at least two along the height of the stack stacked and / or at least two along the width of the stack of juxtaposed flow blocking elements are provided.

Another development of the invention provides that at least one flow blocking element is designed in the manner of a blind, a vertical slatted curtain or a shutter.

Another advantageous development of the invention provides that at least one flow blocking element is associated with a preferably frame-like guide arrangement, facing the stacking space Side forms a contact surface for the stack wood. If the dryer is loaded, for example by means of a forklift truck, the driver of the forklift can, for example, drive the stacking wood so far into the dryer that it comes into contact with the guide arrangement and is thus signaled to the driver that the position desired for the drying process has been reached ,

Another advantageous development of the invention provides that the guide arrangement has vertical supports, of which at least one in the direction of the width extension of the stack is formed areal for areawise foreclosure of the stack entry level against the flow of the drying medium. In this embodiment, flat trained parts of the guide assembly, for example, and in particular serve to foreclose the ends of stacked wooden boards against the flow of the drying medium and thus to prevent the board ends dry too quickly and it comes to cracking.

A movement or mobility of a flow blocking element for changing the shape and / or the cross section of the inlet opening in a stack entrance level or stack exit level is understood in accordance with the invention to mean that the respective flow blockade element is arranged in the stack entrance level or stack exit level and in the flow direction as close to the respective level in that the region of the cross section of the stacks covered by the flow blocking element is directly sealed off from the flow of the drying medium.

The invention will be explained in more detail with reference to the accompanying drawing, in which highly schematically an embodiment of an inventive Drying device is shown. In this case, all described, shown in the drawings and claimed in the claims characteristics taken alone and in any suitable combination with each other the subject of the invention, regardless of their summary in the claims and their dependency and regardless of their description or representation of the drawing.

FIG. 1:

stark schematisiert einen Längsschnitt durch ein Ausführungsbeispiel einer erfindungsgemäßen frontstaplerbeschickbaren Trocknungsvorrichtung,

FIG. 2:

einen Schnitt entlang einer Linie A-A in FIG. 1 und

FIG. 3:

einen Schnitt in einer horizontalen Ebene durch ein leicht abgewandeltes Ausführungsbeispiel einer Trocknungsvorrichtung gemäß FIG. 1

It shows:

FIG. 1:

very schematically a longitudinal section through an embodiment of a frontstoplerbeschickbaren drying device according to the invention,

FIG. 2:

a section along a line AA in FIG. 1 and

FIG. 3:

a section in a horizontal plane through a slightly modified embodiment of a drying device according to FIG. 1

In FIG. 1 an embodiment of a drying device (dryer) 2 according to the invention is shown, which is used for drying of stacking wood and has a stacking space 4. The stacking space 4 and the stacks 8 are accessible through a gate 6, and the dryer can be loaded with open door 6, for example by means of a stacker, with stacking wood. The pile wood is in FIG. 1 shown symbolically and provided with the reference numeral 8.

The drying device 2 further comprises flow-through means for the flow of the stacked wood 8 with drying air or another drying medium, wherein the flow agents in FIG. 1 by a reversible Recirculation fan 10 are symbolized. The recirculation fan 10 can be controlled by a control device not shown in the drawing and controlled by a frequency converter in its speed and direction of rotation. According to the rotational direction of the circulating air fan 10, a flow of the drying medium is formed in one or the other direction, as in FIG. 1 symbolized by a double arrow 12. The recirculation fan 10 is arranged in a space below a ceiling 14 of the drying device 2, which is separated from the stacks 8 by a false ceiling 16.

To heat the drying medium heating coil are arranged in the flow path, the in FIG. 1 designated by the reference numerals 18, 18 '. For the supply of fresh air or for the removal of exhaust air to and from the dryer 2, supply / exhaust flaps 20, 20 'are provided.

In order to be able to moisturize the stacked wood 8 according to the respective requirements, a spraying device 22 is provided.

The flow direction of the drying medium in a first direction of rotation of the circulating air fan 10 is in FIG. 1 In this flow direction, an opening 26 (dotted portion of the entrance plane) forms an inlet opening for the entry of the drying medium into the stacks 8, while an opening 28 forms an outlet opening for an exit of the drying medium from the stacks 8 forms.

According to the invention, at least one flow block cradle element is provided, which is movable to change the shape and / or the cross section of the inlet opening 26 in the stack entry plane.

In the illustrated embodiment, a flat formed Strömungsblockadelement 30 is provided, which is movable along the stack entry plane. For movement of the flow blocking element 30 along the stack entry plane, the same is associated with a drive device, not shown in the drawing, for example in the form of a linear drive, wherein a control device, also not shown, is provided for driving the drive device.

Out FIG. 2 making a cut along a plane AA in FIG. 1 shows, it can be seen that the flow blocking element 30 is formed flat and in the manner of a flow bulkhead. By a double arrow 33 is in FIG. 2 indicated that the flow blocking element 30 is movable in the vertical direction, ie in the direction of the height extent of the stack 8 and can assume different positions in this direction, in each of which a vertical region of the stack 8 is sealed off against a flow through the drying medium, while the other vertical Regions of the stack 8 are flowed through the drying medium.

Out FIG. 2 Furthermore, it can be seen that along the width extension of the stack 8, ie in the horizontal direction, laterally spaced apart from the flow blocking element 30, a further flow blocking element 31 is provided which corresponds in function and construction to the flow blocking element 30. According to the respective requirements, the flow blocking elements 30, 31 can be moved vertically or independently of each other vertically.

The control of the flow blocking elements 30, 31 associated drive means, for example can be formed by linear actuators, for example, can be time-controlled, so that the flow blocking elements 30, 31 move according to a time schedule or time cycle defined for the respective drying process. However, it is also possible for the control device to drive the drives of the flow blocking elements 30, 31 as a function of drying parameters (wood moisture / air velocity) which are sensed by at least one sensor or a plurality of sensors spaced spatially from one another in the stacks 8. For this purpose, in the illustrated embodiment (see. FIG. 1 ) Sensors for sensing the speed of the drying medium (air velocity) are provided, of which in FIG. 1 one is designated by the reference numeral 34. In addition, in the illustrated embodiment, sensors for sensing the moisture of the wood are provided, from the in FIG. 1 one is provided with the reference numeral 36.

According to the respective requirements, the movement of the flow blocking elements 30, 31 can be time-controlled. However, it is also possible to control the movement of the flow blocking elements 30, 31 during the drying process as a function of measured drying parameters and thus to adapt to the course of the drying process.

In FIG. 1 the flow blocking element 30 is shown in the immediate vicinity of the stack entry plane (in the direction of the arrow 24 corresponding flow direction). In order to maintain the function of the flow blocking element 30 even after reversal of the direction of rotation of the circulating air fan 10 and thus reversal of the flow direction of the drying medium, can in the Stapelaustrittsebene, ie at the flow blocking elements 30, 31 opposite end may be provided corresponding flow blocking elements, which are not shown in the drawing. While at the arrows 24, 24 ', 24 "corresponding flow direction of the stack 8 in FIG. 1 left bounding plane of the entrance level and the the stacks 8 in FIG. 1 the right-bounding plane forms the stack exit plane, forms upon reversal of the flow direction of the stack 8 in FIG. 1 right bounding plane the stack entry level and the stack 8 in FIG. 1 left bounding plane the stack exit plane. Unless in the in FIG. 1 the stack 8 right bounding plane is provided a Strömungsblockade element 30 corresponding flow blocking element, so both flow blocking elements are moved synchronously to each other, so that they are aligned in their respective position along the stack entrance plane or stack exit plane in the flow direction aligned. The same applies to any further flow blocking elements provided, for example the flow blocking element 31.

The flow blocking elements 30, 31 are guided vertically on guides of a guide arrangement which, in the illustrated embodiment, has laterally spaced supports 38, 40, 42 ( FIG. 2 ).

These supports 38, 40, 42 may be formed flat along the width dimension of the stack 8 for the area-wise solid foreclosure of the chamber inlet level against the flow of the drying medium. Are side by side 2 stacked wood, so the board ends of the individual wooden boards of the respective stack are shielded or sealed off against a Beströmung with the drying medium, so that is prevented in this way that the board ends drying too fast, which could lead to cracking.

In FIG. 2 Below are shown schematically in the stacking of wood essential dimensional parameters. The board length of the individual wooden boards with L and the depth of a wooden package with the package depth T is called. The height of a package is denoted by H, while the thickness of chess woods used for stacking is designated by KH. On this basis, the flow blocking element 30 can be dimensioned, for example, such that its extent in the vertical direction corresponds to the package height H plus 1 to 2 square timber heights KH. For example, the flow blocking element 30 can also be dimensioned so that its extent in the vertical direction corresponds, for example, to a maximum of half the total stacking height.

FIG. 3 shows a section in a horizontal plane through a slightly modified embodiment of the drying device 2. The modification consists in that laterally next to each other three flow blocking elements 30, 31, 32 are provided, which are guided on laterally spaced apart supports 38, 40, 42, 44. Shown is a constellation in which three stacks of wood are arranged side by side along the width of the stack 8. How out FIG. 3 it can be seen, the board ends of the individual wooden boards are each shielded by the planar formation of the supports 38, 40, 42, 44 against a flow with the drying medium, so that too fast drying of the board ends and thus cracking are prevented.

At reference numeral 46 is in FIG. 3 indicated that the individual wooden packages with lateral spacing stacked to each other.

For constructive reasons and to avoid damage to the side walls 48, 48 'of the drying device 2 through the wooden packages when loading or unloading the dryer 2 is usefully chosen a protective distance between the wooden packages and the respective side wall of, for example, about 20 cm. In order to prevent in this way a fluidic short circuit between the inlet opening and the outlet opening is formed and the drying medium thus does not pass through the stack wood, but rather flows past the wood stacks, shielding plates 50, 50 'are usually provided on the side walls. According to the invention, the lateral supports 38, 44 can assume this function by constructive adaptation, so that the shielding plates 50, 50 'can be dispensed with.

During the drying process, the drive device controls the drive devices associated with the flow blocking elements 30, 31 such that the flow blocking elements 30, 31 occupy different vertical positions consecutively in time. In the respective vertical position, a lying behind the area of the wood stack is shielded against a flow with the drying medium, where the drying process in the manner described further proceeds by moisture is transported from the interior of the wooden boards to the surface. In the vertical areas which are not sealed off from the drying medium and thus flowed around by them, the drying process continues by transporting moisture away from the surface of the wooden boards.

The invention thus enables targeted influencing the drying process. It provides a drying device that not only ensures rapid and uniform drying, but in particular the consumption of electrical energy is reduced. In this way, the emission of climate-damaging CO2 is reduced. The invention thus has a high social benefit.

The embodiment according to FIG. 1 represents a frontstoplerbeschickbare drying device. While maintaining the basic principle of the invention, the drying device according to the invention can also be designed as a railroad-chargeable or otherwise feedable drying device.

To form stacks of wood (stacked wood), the individual wooden boards are usually stacked on square timbers. This means that there is a gap between the underside of the respective wood stack and the bottom of the drying device. In order to avoid a fluidic short circuit, in which the drying medium does not flow through the stacked wood, but undesirably directly between the underside of the respective wood stack and the bottom of the dryer, can in the vertical direction in these areas of the stack entrance level or in the immediate vicinity of one fixed flow aperture may be provided, which can be conveniently attached to the respective supports of the guide assembly. The flow restrictor, for example in the form of a fixed flow plate, prevents the drying medium from undesirably flowing directly between the underside of the respective wood stack and the bottom of the dryer and thus forms a fluidic short circuit. According to such a "bottom panel" can in the area of the Dekke the drying device in the stack entrance level or immediately before a "ceiling panel" may be provided, which can be conveniently attached to the supports of the guide assembly and is prevented by the fact that forms a fluidic short circuit between the top of the stacking wood and the ceiling of the drying device.

The drying device according to the invention is particularly well suited for drying sawn timber. However, it is also suitable for drying other hygroscopic drying material.

In the various figures of the drawing and the various embodiments, the same or corresponding components are provided with the same reference numerals. As far as components are omitted in the figures of the drawing for reasons of illustration or illustration, the components in question in each case in the other figures are complementary to complement. It will be apparent to those skilled in the art that the features of the individual embodiments are also interchangeable among the embodiments, which may be provided so identical or meaningful in the other embodiments with respect to an embodiment disclosed features. It will also be apparent to those skilled in the art that the features disclosed with respect to the individual embodiments further develop the invention in isolation, that is independently of the further features of the particular embodiment.

Claims (15)

Drying device (2) for drying stacked wood (8),
with a storage space (4) for receiving the stacked wood (8),
with flow media (10) for the flow of the stacked wood (8) with drying air or another drying medium,
wherein an air inlet opening (26) is provided for entry of the drying medium into the stacks (8) in a stack entry plane,
marked by
at least one flow blocker (30) movable to alter the shape and / or cross-section of the entrance opening (26) in the stack entry plane. Drying apparatus according to claim 1, wherein the flow-through device (10) is reversible, and wherein the discharge of the drying medium from the stack (8) an outlet opening (28) is provided in a stack outlet plane, characterized by at least one flow blocking element that is movable in the stack outlet plane for changing the shape and / or the cross section of the outlet opening (28). Drying device according to one of the preceding claims, characterized in that at least one flow blocking element (30) is formed flat and is vertically movable along the stack entry plane or the stack exit plane. Drying device according to one of the preceding claims, characterized in that at least one flow blocking element (30) along at least one axis is horizontally and / or vertically movable. Drying device according to one of the preceding claims, characterized in that at least one flow blocking element (30) is associated with a drive device. Drying device according to claim 5, characterized by a control device for controlling the drive device. Drying device according to claim 6, characterized in that the control device controls the drive device during the drying process time-controlled. A drying device according to claim 6 or 7, characterized by at least one sensor (34; 36) for sensing at least one parameter in the drying Stacking space (4), wherein the control device for controlling at least one flow blocking element in response to output signals of the sensor (34, 36) is designed and set up. Drying device according to one of the preceding claims, characterized in that at least two preferably independently movable flow blocking elements (30, 31) are provided. Drying device according to one of the preceding claims, characterized in that at least two along the height of the stack (8) arranged one above the other and / or at least two along the width of the stack (8) juxtaposed Strömungsblokkadeelemente (30, 31) are provided. Drying device according to one of the preceding claims, characterized in that at least one flow blocking element is designed in the manner of a Venetian blind, a vertical blinds or blinds. Drying device according to one of the preceding claims, characterized in that at least one flow blocking element (30) is associated with a preferably frame-like guide arrangement, the stack (8) facing side forms a contact surface for the stack wood (8). Drying apparatus according to claim 12, characterized in that the guide arrangement comprises vertical supports (38, 40, 42), at least one of which in the direction of the widthwise extension of the stacks (8). is flat formed for areawise foreclosure of the stack entry level against the flow of the drying medium in the board ends. Drying device according to claim 13, characterized in that the outer vertical guide supports (38, 44) at the same time also result in a partitioning up to the two side walls of the dryer. Drying device according to claim 13 or 14, characterized in that on the guide supports (38, 44) below and / or above additionally fixed partition plates are attached.

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