EP2929266B1 - Method for drying wood - Google Patents

Description

The invention relates to a method for drying wood in a container for receiving the wood.

Such methods of drying wood are known per se. Wood to be dried is placed in a container and dried by means of a heated stream of air. For this purpose, ambient air is introduced from outside and heated and passed through the container. The heated air also heats the wood so that water inside it evaporates and is transported out of the tank with the air. Due to the need to heat air and direct it through the containers via a blower or the like, a high thermal or mechanical effort is currently required for drying wood in such devices. When heated by heated air, it can also come to a purely near-surface heating, which can lead to a closure of near-surface voids in the wood.

From the WO 2012/042099 A1 a drying apparatus is known with a container for wood to be dried, in which drying apparatus in the container arranged heating elements cooperate with fans to allow a material drying. The heating elements can be rotated by means of a rotating device. Aeration of the container takes place with drying air from a boiler room. The object of the present invention is therefore to reduce the effort required for drying wood and to specify a corresponding method for this purpose.

The object is achieved by a method according to claim 1. A development of the invention is the subject of subclaim 2.

Furthermore, further features not claimed in the claims are disclosed for further embodiment of the invention. In some cases, effects can occur which go beyond the buzzer of the individual effects described below. The description, in particular in conjunction with the figures, additionally characterizes and specifies the invention.

• Einlegen des Holzes in einen Behälter,
• Einleiten von Wärme über in dem Behälter angeordnete, erwärmbare Platten, welche auf weniger als 150° C, insbesondere weniger als 90° C erwärmt werden, dadurch gekennzeichnet, dass folgender Schritt ausgeführt wird:
• Belüften des Behälters durch Umgebungsluft, wobei das Einleiten von Wärme über die Platte während einer Aufheizphase erfolgt, die sich über einen Zeitraum von einem bis sechs Tagen, insbesondere zwischen einem und vier Tagen erstreckt, und wobei das Belüften des Behälters während einer Trocknungsphase erfolgt, welche sich über einen Zeitraum von ein bis zehn Tagen, insbesondere zwischen zwei und acht Tagen erstreckt.

According to claim 1, there is provided a method of drying wood comprising the steps of:

• Placing the wood in a container,
• Introducing heat via heatable plates arranged in the container, which are heated to less than 150 ° C, in particular less than 90 ° C, characterized in that the following step is carried out:
• Ventilating the container by ambient air, wherein the introduction of heat across the plate during a heating phase, which extends over a period of one to six days, in particular between one and four days, and wherein the venting of the container takes place during a drying phase, which extends over a period of one to ten days, in particular between two and eight days.

The ambient air may be cold air supplied from outside. An advantage of this method is seen in that the heat is transferred via heat radiation from the plates to the wood. This warms the wood evenly. The heated air is discharged as soon as it has reached a high relative humidity and can absorb little or no further water. To speed up the drying process can Circulating fans be provided. The drying process is shortened in time by about 30 to 40%.

The air is heated according to the invention to lower temperatures than is provided in the prior art. Facilities for heating the air are relatively powerful, so they require a high energy input during operation. This high energy input degrades the overall efficiency of conventional drying equipment which heats the wood with heated air. By heating the air to lower temperatures, it can absorb the moisture contained in the wood well.

According to the invention, the introduction of heat across the plate during a heating phase, which extends over a period of one to six days, in particular between one and four days. The venting of the container takes place during a drying phase, which extends over a period of one to ten days, in particular between two and eight days. During the drying phase, ambient air can be supplied discontinuously, for example at intervals of about 10 minutes, in order to force the water laden air out of the container and to absorb further moisture. The ambient air can be previously heated as described in the previous paragraph.

It is provided in one embodiment of the method according to claim 2, the ambient air before being introduced into the container to a temperature below 80 ° C, especially less than 70 ° C, more preferably less than 60 ° C to heat.

• einen Behälter zur Aufnahme des Holzes,
• eine Wand des Behälters ausbildende Platte, wobei die Platte erwärmbar ist und Holz zumindest teilweise an der Platte anliegt. Kennzeichnend ist vorgesehen, dass die Platte über einen längsbeweglichen Aktor in einer horizontalen Lage aus dem Behälter ziehbar ist.

Suitable for carrying out the method is a device for drying wood, comprising:

• a container for holding the wood,
• a wall of the container forming plate, wherein the plate is heatable and wood at least partially rests against the plate. Characteristically, it is provided that the plate can be pulled out of the container via a longitudinally movable actuator in a horizontal position.

In the container, the wet, to be dried wood can be arranged and removed after the drying process. The heat required to dry the wood can be introduced through the plate. In addition, a pressure difference, with which air must be passed through the container, lower, whereby the required power for the fan is correspondingly lower. The energy required to dry wood is lower in this device, because the spatial distance between the heater, or heating elements is repealed by quasi the container at the same time serve as heating elements. This makes it possible to warm the wood in a warm-up phase over all three major forms of heat transfer, namely heat radiation from the plates to the wood, heat conduction between the plates and the wood and convection from the plates to the air and the so heated air on the wood. Since the distance between the plates and the wood is relatively low, no fans are required for convection heat transfer per se. Fans are used in a drying phase to exchange water laden air from the tank with dry air. The energy required for drying wood is thus lower than in the known state of the art.

In a first advantageous embodiment, it is provided to arrange tubes on the plate, which are fluid-conductively connectable to a heating device.

The heating device may in particular be a boiler heated with wood or wood residues and / or waste heat from biogas plants. An underlying idea of the invention is to improve the sustainability of wood as an energy source, while considering the overall efficiency from deforestation to combustion at the customer. If, for example, other energy carriers and / or high amounts of electrical power have to be used to dry the wood, these must be included in the total balance. In the wood used for drying wood residues and waste which can not be sold anyway, the sustainability of wood as an energy supplier can be improved overall.

In a further advantageous embodiment, the tubes are connected via a weld with the plate.

By this configuration, a connection between the tubes and the plate is created, which is characterized by a good heat conduction.

In an advantageous embodiment of the weld, the tubes are each connected to the plate via two welding beads running on both sides on the tubes and parallel to the tubes.

The weld beads thus provide a cohesive connection between the plate and an outside of the tubes so that a large heat transfer from the tubes to the plates is made possible.

According to a further embodiment, the container is at least partially tiltable.

By this configuration, the container can be tilted with the wood therein total to remove the wood after drying easier from the container.

In a further advantageous embodiment, the plates can be pivoted from a horizontal position into a tilted position.

By this alternative or complementary design to a tiltable chamber, the plates can be pivoted to the removal of wood from the container in the tilted position, after which the wood can be removed by suitable means from the container.

According to a further advantageous embodiment, a conveyor for conveying wood from the container is arranged below the plate, wherein lying on the plate wood slips in the tilted position on the conveyor.

The conveyor allows removal of dried wood from the container. The drying process can thus be partially automated.

In a further advantageous embodiment, the plate can be pulled over a longitudinally movable actuator in a horizontal from the container.

The longitudinally movable actuator may be a linear motor, a hydraulic or pneumatic cylinder, or a rack drive. The actuator thus allows extraction of the plates after the drying process and / or before loading the container with wood to be dried.

According to a further advantageous embodiment, a plurality of plates are arranged one above the other.

The plurality of superimposed plates may be pivotally mounted in the container as described above and / or pulled horizontally out of the container via the previously described actuator. Accordingly, to fill the container with wood to be dried first lower plates are loaded and successively the plates lying further up. To unload the container, the plates lying further down can first be pulled out, whereupon the dried wood can be removed from the container at the bottom by suitable means.

According to a further embodiment, therefore, a conveyor is arranged in the container for unloading the container, wherein the plates are arranged opposite to the conveyor so that wood located on the plates falls upon withdrawal of the plates on the conveyor.

The conveyor may be, for example, an endless belt, for example a widened metal chain and / or a textile or rubber belt. This conveyor allows a rapid and semi-automatic unloading of the container.

The term wood in particular logs or shredded with cutting tools wood in the form of so-called wood chips are included. Also by blunt or shattered tools produced wood in the form of so-called shredded wood, also residual wood, small wood, woodcuts and old wood is covered by the term wood.

• Figur 1: schematisch in einer Seitenansicht eine Ausführungsform einen Behälter zum Trocknen von Holz mit daran angeordneten erwärmbaren Platten,
• Figur 2: schematisch einen in Figur 1 mit "A" gekennzeichneten Schnitt durch den Behälter,
• Figur 3: schematisch einen in Figur 1 mit "B" gekennzeichneten Schnitt durch den Behälter,
• Figur 4: schematisch in einer geschnittenen Draufsicht eine Trockenkammer zum Trocknen von Holz mit darin angeordneten Behältern, einer Heizeinrichtung, einem Vorlauf für erwärmtes Wasser und einen Rücklauf für abgekühltes Wasser,
• Figur 5: schematisch eine Seitenansicht einer Ausführungsform mit einem kippbaren Behälter, welche sich in einer gekippten Lage befindet,
• Figur 6: schematisch einen Schnitt durch einen Behälter mit darin befindlichem Holz,
• Figur 7: schematisch eine Seitenansicht des kippbaren Behälters, welcher sich in einer horizontalen Lage befindet,
• Figur 8: schematisch im Schnitt eine Ausführungsform einer Vorrichtung zum Trocknen von Holz mit kippbaren erwärmbaren Platten und einer Fördereinrichtung, wobei sich die Platten in einer horizontalen Lage befinden,
• Figur 9: schematisch im Schnitt die in Figur 8 gezeigte Vorrichtung zum Trocknen von Holz in einem Zustand, in der die Platten in einer gekippten Lage sind und auf den Platten befindliches Holz auf die Fördereinrichtung rutscht,
• Figur 10: schematisch im Schnitt eine weitere Ausführungsform einer Vorrichtung zum Trocknen von Holz mit mehreren übereinander angeordneten Platten, welche über Aktoren seitlich aus dem Behälter herausgezogen werden können,
• Figur 11: schematisch im Schnitt die in Figur 10 gezeigte Ausführungsform, bei der die Platten seitlich herausgezogen sind und auf ihnen befindliches Holz aus eine Fördereinrichtung fällt, und
• Figur 12: eine in Figur 3 mit "X" gekennzeichnete Detailansicht mit einem auf die Platte aufgeschweißten Rohr.

In the following, an exemplary embodiments will be explained in more detail with reference to the figures. Show it:

• FIG. 1 FIG. 2 schematically shows, in a side view, an embodiment of a container for drying wood with heatable plates arranged thereon, FIG.
• FIG. 2 : schematically a in FIG. 1 with "A" marked section through the container,
• FIG. 3 : schematically a in FIG. 1 with "B" marked section through the container,
• FIG. 4 FIG. 2 schematically shows, in a sectional top view, a drying chamber for drying wood with containers arranged therein, a heating device, a heated water flow and a return flow for cooled water, FIG.
• FIG. 5 Fig. 1 schematically shows a side view of an embodiment with a tiltable container which is in a tilted position,
• FIG. 6 FIG. 2 schematically shows a section through a container with wood inside, FIG.
• FIG. 7 FIG. 2 schematically shows a side view of the tiltable container, which is in a horizontal position. FIG.
• FIG. 8 FIG. 2 is a schematic sectional view of an embodiment of a device for drying wood with tiltable heatable plates and a conveying device, wherein the plates are in a horizontal position, FIG.
• FIG. 9 : schematically in section the in FIG. 8 shown apparatus for drying wood in a state in which the plates are in a tilted position and slipping wood on the plates on the conveyor,
• FIG. 10 FIG. 2: schematically, in section, another embodiment of a device for drying wood with a plurality of plates arranged one above the other, which can be pulled laterally out of the container via actuators;
• FIG. 11 : schematically in section the in FIG. 10 shown embodiment in which the plates are pulled out laterally and wood located on them falls from a conveyor, and
• FIG. 12 : one in FIG. 3 with "X" marked detail view with a tube welded onto the plate.

In the figures, the same or equivalent components are provided in part with the same reference numerals.

FIG. 1 shows from a lateral perspective a container 1, which is designed to receive wood 2. The container 1 is constructed substantially parallelepipedally from a plurality of walls 3. At least one wall 3 directly coming into contact with the wood 2 is designed as a heatable plate 4. For heating the plate 4, a meandering tube 5 is welded to the plate 4. The tube 5 is traversed by a heated fluid, in particular water. The heated fluid releases heat to the tube 5 during operation. The thus heated tube 5 gives the heat to the plate 4 on. As a result, the plate 4 is heated. Between the plates 4 remain free spaces 8 for ventilation of the container 1. It is provided that at least two opposite sides, that is, a left and a right side or an upper and a lower side are permeable to air. Optimal results can be achieved if all sides are permeable to air. The clearances 8 improve the process of removing the moist air.

The tube 5 can be connected in a manner not shown with a conduit, in particular a flexible conduit. In one embodiment, the tube 5 is separable from the conduit to transport and move the container 1 for filling with wood to be dried and for draining dried wood tilt. The transport can be done for example via a forklift, which has rotatable forks. The tube 5 can be closed by ball valves 6, so that therein water does not leak during transport. In order to facilitate the picking up and transport of the container 1 with a forklift truck, steel profiles 10 are arranged in a floor area 11, which are also closed at the bottom, so that the container 1 can be rotated on the forks of the forklift to discharge dried wood 2.

FIG. 2 schematically shows a in FIG. 1 with "A" marked section through the container 1. In the bottom portion 11, an air-permeable bottom 7 is arranged. The air permeability is achieved by spaced profile parts.

FIG. 3 shows an in FIG. 1 with "B" marked section through the container 1. The container 1 has two chambers 12 for receiving the wood 2. On two outer plates 4, the tubes 5 are arranged on the side facing away from the wood 2 side. On an inner plate 4 ', the tubes 5 are mounted on a side facing the wood 2. The tubes 5 are covered with a V-shaped mudguard 13 so that the wood 2 does not damage the tubes 5 when filling or emptying the container 1.

One in FIG. 3 Enlarged area marked "X" is in FIG. 12 shown. It can be seen that the tubes 5 are connected to the plates 4 via a weld 14. The weld 14 is formed by two parallel to the tubes 5 extending weld beads 15. The weld beads 15 serve both for mechanically fixing the tubes 5 to the plates 4 and for improving the heat transport from the tubes 5 to the plates. The weld beads are applied relatively bulky, so that they cover almost half of the surface 16 of a tube 5 and cover the largest possible area in the region of a connection 17 of the weld bead 15 to the plate 4. This embodiment allows a high heat transfer Q 'of the tubes 5 and the water therein to the plates 4. The plates 4 transmit the heat directly to the wood 2 from. The heat transfer takes place predominantly via heat radiation,

Heat conduction and convection directly in the vicinity of the wood, whereby losses are kept low.

A container 1 for industrial use between 0.2 and 3.2 m, in particular between 0.5 and 3 m high, between 1 and 4.2 m, in particular between 1.2 and 4 m wide and between 0.2 and 3.3 m, in particular between 0.5 and 3 m deep. In these dimensions, a tube length of the meandering laid and welded in the manner described above tube 5 of about 15 to 30m is suitable to ensure a large heat transfer from the water to the wood.

FIG. 4 shows in a partially sectioned view schematically a device for drying wood with a drying chamber 18, which is dammed out over thermal insulation panels 19. In the drying chamber 18 a plurality of configured as described container 1 are arranged. The containers 1 are connected via a feed 20 and a return 21 to a heater 22. The heater 22 has a solid fuel boiler 23, in which in a manner not shown, a combustible material, in particular wood, can be burned to heat the water. For example, wood chips can be used with an automatic feeder for heating and / or a biogas plant. Heated water can be temporarily stored in two buffer memories 25 shown in plan view. By means of pumps 24, the heated water first passes into the supply line 20. Heated water is branched off from the supply line 20 and passed to the tubes 5 of the individual containers 1. For uniform distribution of heat to the container 5 valves not shown may be provided which can be opened or closed manually or automatically completely or partially. Through the return 21 cooled water gets back into the heater 22 (two-pipe system). However, if necessary, a single-tube system not shown in the figures may be used. The described heating device 22 can also be used for heating in the FIGS. 5 to 11 shown drying chambers 18 ', 18 "and 18"' are used. It is considered particularly advantageous that the heat is released directly to the wood is used and as an intermediate medium water, which gives almost lossless heat and thus emits directly from the heater to the wood.

FIG. 5 shows a pivotable drying chamber 18 'in a pivoted position. In the drying chamber 18 'a plurality of heatable plates 4 are arranged. Via a hydraulic cylinder 26, the entire drying chamber 18 'can be pivoted, so that the wood 2 can be easily unloaded. FIG. 6 shows the in FIG. 5 shown drying chamber 18 'in a front view. The drying chamber 18 'has a plurality of continuous chambers 12'. FIG. 7 shows the container 1 'in a non-pivoted, horizontal position.

FIG. 8 shows a further embodiment of a drying chamber 18 "with pivotable plates 4 '. The plates 4' are pivotally connected to the walls 3 'of the drying chamber 18" and connected by an actuator 27 of one in FIG. 8 illustrated horizontal position in an in FIG. 9 tilted position shown tilted. The actuator 27 may be formed for example by a hydraulic or pneumatic cylinder. The drying chamber 18 "has at least two plates 4 'arranged on opposite walls 3. The plates 4' have on their underside tubes 5 which can be flowed through by heated water in the manner already described, immediately below the plates 4 ' a conveyor 28 is provided, which can transport wood from the drying chamber 18 'via a circulating belt 29. The plates 4' are arranged relative to the conveyor 28 on the walls 3 'such that the wood 2 on them is in the pivoted position the conveyor 28 slips, see FIG. 9 , As a result of this embodiment, the drying process can be automated at least partially, since wood 2 to be unloaded can be conveyed out of the drying chamber 18 "without manual intervention.

The FIGS. 10 and 11 show in a further embodiment, a drying chamber 18 "'with a plurality of the container 1'" or the drying chamber 18 '"pull-out plates 4". The plates 4 "are longitudinally movably arranged in respective opposite walls 3" of the container 1 '" be pulled out via an actuator 30, as in FIG. 11 shown. The actuator 30 may be formed by a hydraulic or pneumatic cylinder, a linear drive or a rack and pinion. To unload the container, the plates 4 "can be pulled out via the actuators 30. The wood 2 falls onto a conveyor 28, so that it can be transported out of the container 1"'. To ensure that no wood 2 falls next to the conveyor 28, inclined baffles 31 are provided.

LIST OF REFERENCE SIGNS

1

container

2

Wood

3

wall

4

plate

4 '

plate

4 '

plate

4 ' "

plate

5

pipe

6

ball valve

7

ground

8th

free space

9

profile part

10

steel section

11

floor area

12

chamber

12 '

chamber

13

mudguard

14

welding

15

bead

16

surface

17

connection

18

drying chamber

18 '

drying chamber

18 "

drying chamber

18 " '

drying chamber

19

thermal insulation board

20

leader

21

returns

22

heater

23

Fired furnaces

24

pump

25

buffer memory

26

hydraulic cylinders

27

actuator

28

Conveyor

29

tape

30

actuator

31

baffle

Claims (2)

1. Method for drying wood, comprising the steps:

   - placing the wood (2) in a container (1, 1' 1", 1'")

   - introducing heat via heatable panels (4) which are arranged in the container (1, 1' 1", 1"') and which are heated to less than 150°C, in particular less than 90°C,

   characterized in that the following step is carried out:

   - ventilating the container (1, 1' 1", 1"') with ambient air, wherein the introduction of heat via the panel takes place during a heating phase which extends over a duration of one to six days, in particular between one and four days, and wherein the ventilation of the container takes place during a drying phase which extends over a duration of one to ten days, in particular between two and eight days.
2. Method according to claim 1, wherein the ambient air is heated to a temperature below 80°C, in particular less than 70°C, particularly preferably less than 60°C, before being introduced into the container (1, 1' 1", 1'").

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