CH713511B1 - Process and device for drying logs. - Google Patents

Abstract

The invention relates to a method for drying a log (1), the log having a first and a second end face (S1, S2), an outside (1f) and an entire length (L), in which a longitudinal bore (1b) is produced , which extends along the entire length (L) from the first to the second end face (S1, S2), so that on the first end face (S1) an inlet opening (1c) and on the second end face (S2) an outlet opening (1d) is produced, the longitudinal bore (1b) having an inner side (1e) in that the log (1) is held in a substantially vertical position and a drying gas (G) is supplied from below the log (1) in such a way that the drying gas (G) also flows through the longitudinal bore (1b), and in that the drying gas (G) flows directly around both the inside (1e) and the outside (1f), so that the log (1) is simultaneously exposed to the inside (1e) forth as well as from the outside (1f) he r is dried. The invention also relates to a wood drying device for carrying out the method for drying logs (1).

Description

The invention relates to a method and a device for drying logs.

State of the art

[0002] Wood drying refers to a process for removing moisture from wood. With regard to drying processes, a particular distinction is made between kiln-dried wood, which is dried in a controlled manner in a drying chamber, and air-dried wood, which slowly loses moisture simply by lying covered in the open air. The goal of controlled drying processes is that the moisture content of the wood reaches a so-called usage moisture content. This is usually in the range between 6% and 16% wood moisture based on the weight of oven-dried wood, i.e. wood in a practically water-free state. Forest-fresh wood, on the other hand, contains around 40% to 60% water. In order to obtain high quality wood, controlled, artificial drying of the wood is required to avoid fungal growth, discoloration, cracking, warping or warping of the wood. A particular disadvantage of artificial drying is the energy consumption. Air drying has the advantage that no energy has to be supplied. The disadvantage is that drying takes a long time and the wood loses quality or is damaged in such a way that it becomes unusable.

A method for drying pine logs is known from document KR101359476B1. With this method, a continuous longitudinal bore is drilled along the log, the outside of the log is covered with a waterproof film, and then warm air is directed through the longitudinal bore of the log lying on it to dry the log from the inside out. This reduces the likelihood of cracks forming on the outside of the log.

This drying process allows pine logs to be dried in one piece. Pine is a soft wood and therefore easy to dry. However, this known drying method is not suitable for completely drying logs consisting of wood species that are difficult to dry, in particular wood species such as hardwood, and in particular beech wood.

Another method for drying logs is known from document CA1129681A. This process is also about reducing cracks in the trunk caused by drying. In this process, a continuous longitudinal bore is drilled along the log. Subsequently, a plurality of such trunks are stacked on top of one another running in a horizontal direction, with the mutual distance between the stacked trunks being able to be very small, because the longitudinal bore is accessible for drying air.

Presentation of the invention

The object of the invention is to form a more advantageous method and a more advantageous device for drying logs. The method and the device should be particularly suitable for drying logs made of hardwood.

This object is achieved with a method having the features of claim 1. The dependent claims 2 to 10 relate to further advantageous method steps. The object is further achieved with a wood drying device having the features of claim 11. The dependent claims 12 and 13 relate to further advantageous configurations of the wood drying device.

The object is achieved with a method for drying a log, the log having a first and a second end face, an outer side and an entire length, in that a longitudinal bore is produced, which runs along the entire length from the first to the second end face, so that an inlet opening is produced on the first end face and an outlet opening is produced on the second end face, the longitudinal bore having an inner side, in that the log is held in a substantially vertical position and a drying gas is supplied in this way from below the log that the drying gas also flows through the longitudinal bore, and in that the drying gas flows around both the inside and the outside with direct contact to the drying gas, so that the surface of the log is simultaneously deprived of water from the inside and from the outside, and the log is dried in this way.

The object is further achieved with a wood drying device for logs, having a longitudinal bore running along the entire length of the respective log, comprising a plurality of holding devices for logs for holding the logs in a substantially vertical position, the holding devices being in a vertical position Direction are spaced such that at least two logs can be arranged one above the other in the vertical direction. The holding devices are preferably designed in such a way that the inlet opening and the outlet opening of the longitudinal bore of each of the logs can be kept open for the drying gas to flow through.

Water is particularly preferably removed from the vertically arranged log by evaporating it on the surface of the longitudinal bore, by the drying gas located in the longitudinal bore being moistened and by the increase in moisture thereby reducing the density of the drying gas locally in the longitudinal bore is, so that the drying gas located in the longitudinal bore at least partially has a reduced density, which generates a lift on the drying gas located within the longitudinal bore. The effect described, that the moistened drying gas has a lower density and therefore strives upwards, can also occur to a lesser extent on the outside of the log. However, this effect is more pronounced within the longitudinal bore, since the humidified drying gas within the longitudinal bore cannot mix with drying gas from the ambient air inside the longitudinal bore, so that a so-called chimney effect occurs within the longitudinal bore, in which the humidified drying gas can only escape upwards and thereby causes a suction or a movement of the entire column of drying gas located within the longitudinal bore.

In a particularly preferred embodiment, the inner diameter and the length of the longitudinal bore are mutually adapted in such a way that a chimney effect is generated inside the longitudinal bore by the drying gas flowing in from below and rising in the longitudinal bore, and the drying gas thus inside the longitudinal bore has an im Has substantially vertically directed, preferably laminar flow. The upward movement of the drying gas within the longitudinal bore can also be supported by arranging the log in a flow field with drying gas preferably flowing parallel to the log and/or by heating the drying gas supplied to the log. The flow of the drying gas can be generated with a fan, for example. The flowing drying gas and/or the heated drying gas is preferably supplied to the longitudinal bore from below. The natural upward movement of the preferably warm drying gas along the inner surface of the longitudinal bore enables efficient removal of water via the inner surface, and thus enables efficient drying of the log from the inside. In addition, drying gas also flows around the outside of the log, so that the log is dried both from the inside and from the outside. In a particularly preferred embodiment, the drying device is designed in such a way that a chimney effect is also created within the entire drying device, so that the entire log, in particular also its outside, is exposed to this chimney effect or to a stream of rising drying gas, preferably air. Thus, particularly preferably, both the inner surface and the essentially cylindrical outer surface of the log are exposed to this chimney effect, or are surrounded by rising air. This drying process is also particularly advantageous for drying hardwood trunks. It is much more difficult to remove water from hardwood, which is why no attempts have been made to dry hardwood logs in one piece. The drying of whole trunks of hardwood previously led to the problem that these trunks suffocated after being cut and then rotted.

With the drying method according to the invention, very moist and/or freshly felled logs, in particular hardwood logs, can also be dried in a simple manner, in that the logs are arranged vertically in the drying device after the longitudinal bore has been made, and in that the drying method then has at least two method steps comprises a first method step, during which liquid water flows downwards from the logs, and a second method step, during which only evaporated water is removed, which is absorbed by the drying gas from the surface of the longitudinal bore and the outside of the logs

So far, it has been customary to process logs into lumber, for example into boards, and then to dry this lumber. The method according to the invention has the advantage that logs are provided with a longitudinal bore after beating, are then dried and only after drying are processed into sawn timber. This procedure has the advantage that larger construction elements such as beams or beams can be produced, that warping of the wood during drying does not affect the lumber since the lumber is only produced after drying, and that the wood yield is preferably greater. The timber yield of a log can be increased, for example, by knowing the exact mass of a large number of logs, by knowing the dimensions of the desired timber in a CAD model, and by cutting the logs based on this data in such a way that the desired lumber is cut from the logs with as little waste wood as possible.

The logs to be dried using the method according to the invention preferably have an outside diameter in the range of 16 cm to 90 cm and preferably have a length in the range between 100 cm and 1600 cm, with the continuous longitudinal bore preferably having an inside diameter in the range of Has 5 cm to 50 cm.

Surprisingly, it has been shown that beech logs can be dried with the drying process according to the invention. Beech wood is a very common type of wood in Switzerland, but is mainly processed into firewood. Fresh beech wood has a water content of around 50%, with the bark of the beech being impermeable to water. In addition, beech wood is a hardwood, which is why it takes a relatively long time for the water to completely escape. With beech wood there is therefore a great risk that the wood will suffocate during drying, or that mold and bacteria will form, which damage the wood and make it worthless for high-quality products. It is therefore extremely difficult to produce high-quality products such as supporting columns, beams or boards from beech wood. Because beech wood is extremely difficult to dry, it is usually split up in order to allow the large amount of water stored in the wood to drain off as quickly as possible, for example to avoid mold growth. In addition, the splitting creates a larger drying surface, which additionally supports drying. However, wood that has been split in this way can only be used as firewood.

The drying method according to the invention makes it possible for the first time to dry whole beech logs in that, after the tree has been felled, the log is cut to length and its bark is removed, in that a longitudinal hole is then drilled along the entire length of the cut log, and in that the cut log is then cut into is dried in a vertical direction by a drying gas rising from below. The drying of beech wood has been exceptionally difficult because beech wood is particularly prone to discoloration or suffocation due to storage or processing. The discoloration of beech wood can be due to various physiological, microbiological, biochemical and chemical reactions, and can be e.g. biotic, e.g. fungi or bacteria, or can be e.g. abiotic, mostly due to oxidation reactions such as suffocation of the wood . The decisive quality criterion for beech wood, in addition to the trunk dimension and trunk shape, is the avoidance of storage and process-related discolouration, which can occur after the wood has been felled. Such quality-reducing discolouration can occur during storage and drying of the wood, for example through bacterial or fungal attack, or through suffocation of the wood. These discoloration effects can be avoided with the drying process according to the invention. The drying process according to the invention also makes it possible to safely dry large beech logs. The dried beech trunk can then be used to produce high-quality and high-priced products, such as supporting columns, beams or boards, whereby the products, for example a supporting column, can also have large dimensions of, for example, 3, 5 or 8 meters in length, and the supporting column with it suitable for building multi-storey houses, for example.

As a further possibility, the drying method according to the invention for logs can also be carried out in such a way that the felled tree is cut to length to form at least one log but the log is not debarked, that a longitudinal hole is then drilled along the entire length of the log that has been cut to length so that the cut to length The log is then arranged in a drying device running in a substantially vertical direction, and that a drying gas is supplied underneath the log in such a way that the rising drying gas flows around the log through the longitudinal hole and from the outside, with the bark of the log drying and tearing open during the drying process and at least partially falls off, so that the at least partially barkless log is dried from the inside and from the outside.

In an advantageous method step, a stress-relieving cut is created along the entire length of the log, which extends from the longitudinal bore to the outside of the log, and which extends from the first end face to the second end face. Such a stress-relieving cut has the advantage that the wood hardly or no longer tears during drying, which increases the yield of high-quality wood.

The invention is explained below using exemplary embodiments.

Brief description of the drawings

The drawings used to explain the exemplary embodiments show: FIG. 1 a perspective view of a log; FIG. 2 shows a longitudinal section of the log according to FIG. 1; Fig. 3 is a perspective view of a log with a stress relief cut; 4 wood moisture content of a log after 14 weeks without longitudinal drilling; 5 wood moisture content of a log after 14 weeks with a longitudinal bore; 6 wood moisture content of a log with a longitudinal bore at different points in time; 7 schematically shows a drying device; 8 schematically shows a further drying device; 9 shows an example of an arrangement of logs in the drying device; Fig. 10 exemplarily aligned logs arranged one above the other.

In principle, the same parts are provided with the same reference symbols in the drawings.

Ways to carry out the invention

FIG. 1 shows a log 1 in a perspective view and FIG. 2 in a longitudinal section, the log 1 having a first end face S1 and a second end face S2, an outside 1f and an overall length L. The log 1 to be dried is preferably peeled, ie the outermost layer, in particular bark, bast and cambric, has been removed. A longitudinal bore 1b runs along the entire length L of the log 1 from the first end face S2 to the second end face S2, so that the first end face S1 has an inlet opening 1c and the second end face S2 has an outlet opening 1d. The longitudinal bore 1b is preferably designed as a central bore in order to remove the pith of the log.

Advantageously, the central bore is designed as a core bore, and the wood of the core produced thereby is supplied for further use. However, the longitudinal bore 1b could also run eccentrically in the log 1. In addition, the log 1 could also be provided with a plurality of parallel longitudinal bores 1b. Toward the longitudinal bore 1b, the log 1 has an inner side 1e or an inner surface 1e, via which water is removed from the log 1 during the drying process. The log 1 is held in a substantially vertical position during drying, with a drying gas G preferably being supplied from below the log 1 in such a way that the drying gas G flows through the longitudinal bore 1b on the one hand and along the outside 1f on the other hand, so that Both the inner side 1e and the outer side 1f are flowed around directly, ie with direct contact, by the drying gas G, so that water is removed from the log 1 simultaneously via the inner side 1e and the outer side 1f. The drying gas G could also have little or no disturbance outside the log 1, with the drying gas G located within the longitudinal bore 1b moving upwards within the longitudinal bore 1b due to the absorption of water vapor and the associated reduction in specific weight, so that over the Inlet opening 1c drying gas G is sucked into the longitudinal bore 1b.

Advantageously, the inner diameter 1g of the longitudinal bore 1b and the length L of the longitudinal bore 1b are mutually adapted in such a way that a chimney effect is generated within the longitudinal bore 1b by the inflowing drying gas G, and the drying gas G thus has a vertically directed effect within the longitudinal bore 1b , preferably having a laminar flow. This drying gas G flowing through can dry out the inner surface 1e particularly well, or can drain any water or water vapor away from the inner surface 1e particularly well.

Figure 3 shows that along the entire length L of the log 1, a stress-relieving cut 1a was created, which extends from the longitudinal bore lb to the outside 1f of the log, and which extends from the first end face S1 to the second end face S2 . This relaxation cut 1a is particularly advantageous for beech logs, because a beech log can warp moderately or even severely during drying despite careful drying, and the relaxation cut 1a can largely prevent cracking in the log. After drying is complete, the beech log can be processed further, for example into support beams, beams or boards. Since the dried beech wood trunk hardly has any cracks, high-quality wooden parts can be cut from the trunk, and this with a large yield, since there are few cracks.

Figure 3 also shows an additional heating device 2, for example an electric heater, which is arranged in the log 1 according to Figure 1 or Figure 3 within the longitudinal bore 1b, and around which the drying gas G flows, with the heating device 2 adding additional heat energy to the longitudinal bore 1b and feeds it to the drying gas G, and thus increases or accelerates the drying process on the inside 1e, in particular because the heat supplied increases the upward movement of the drying gas G or its flow rate within the longitudinal bore 1b, which increases the gas exchange in the longitudinal bore 1b , so that an increased amount of water vapor can be transported out of the longitudinal bore 1b, and thus the drying process can be accelerated. In an advantageous embodiment, the heating device 2 runs along the entire length L of the log 1 within the longitudinal bore 1b, with the heating device 2 being dimensioned in such a way that it only fills part of the cross-sectional area of the longitudinal bore 1b, so that the drying gas has a free space within the longitudinal bore 1b Flow cross-sectional area is available, which is preferably at least 50% of the total cross-sectional area of the longitudinal bore 1b. The heating device 2 is preferably designed in the form of a hose and, in one possible embodiment, comprises a water hose which runs through the longitudinal bore 1b and through which warm water is conveyed, or, for example, an electrical resistance heater.

Figure 4 shows the wood moisture within a log 1, starting from the outside 1f the moisture in the direction of radial distance inwards at the distance points 1.5 cm, 3 cm, 4.5 cm, 6 cm 7.5 cm , 9 cm 10.5 cm, 12 cm and 13.5 cm. FIG. 4 shows the wood moisture content for a log without a longitudinal bore after a drying time of 14 weeks.

FIG. 5 shows the wood moisture within another log 1 at the same distance points as described in FIG. The log according to FIG. 5 has a longitudinal bore 1b running in the middle of the log and shows the wood moisture content after a drying time of 14 weeks. From Figure 5, the effect of the additional drying via the inner bore 1b, with a vertically arranged log, is clearly recognizable, namely by the fact that the log 1 is also dried from the inside and the wood moisture is thus towards the center, at values 12 and 13 .5 cm decreases.

Figure 6 shows the wood moisture content of a beech log 1 at a radial distance from the outside 1f for a log with a centered longitudinal bore as a function of time, with the 1st removal at the beginning of drying, the 2nd removal after 2 weeks, the 3rd after 5 weeks, the 4th after 8 weeks, the 5th after 11 weeks, the 6th after 14 weeks, the 7th after 17 weeks and the 8th after 20 weeks. It can be seen from FIG. 6 that the wood moisture content of the beech trunk at the 8th removal, ie after 20 weeks, has an essentially constant, low value of about 9 to 11% wood moisture content as a function of the distance from the outside 1f. From this it can be seen that the method according to the invention makes it possible to dry a beech trunk evenly right into its interior. In view of the fact that it was known that it is extremely difficult to dry beech wood, it was surprising that the method according to the invention made it possible to dry beech logs so evenly.

Figure 7 shows an embodiment of a drying device 10 for logs 1, each log 1 having a not shown, along the entire length L of the log 1 running longitudinal bore 1b. The drying device 10 comprises a plurality of holding devices 18 for logs 1 for holding the logs 1 in a substantially vertical position, the holding devices 18 being spaced apart in the vertical direction such that at least two logs 1 can be arranged one above the other. The holding devices 18 keep the respective inlet openings 1c and outlet openings 1d of each longitudinal bore 1b open. FIG. 7 shows only three holding devices 18 as an example, with each log 1 being held by such a holding device 18 . The drying device 10 shown in FIG. 8 comprises a tower-shaped drying chamber 11 with an outer shell 12 open to vapor diffusion, the drying chamber 11 enclosing an interior 10a which has an inlet 10b at the bottom and an outlet 10c at the top for the drying gas G, namely air. Gas-permeable intermediate floors, namely a first intermediate floor 13a, a second intermediate floor 13b and a third intermediate floor 13c, which carry the vertically extending logs 1, are arranged in the interior 10a. Adjacent to the drying chamber 11 are outlet ducts 15a at the top and air inlet ducts 14a at the bottom to let in ambient air G1 at the bottom via the air inlet ducts 14a and to let out the humidified drying gas G or the humidified ambient air G2 at the top via the outlet ducts 15a. In an advantageous embodiment, the buoyancy of the drying gas G caused by the evaporation of water in the longitudinal bore is sufficient to generate an ascending air flow in the interior 10a. However, this effect decreases in particular with increasing drying of the logs 1 . It can therefore prove advantageous to provide devices which force a flow of the drying gas in the interior 10a, for example by conveying the drying gas G, for example with a fan, or by heating the drying gas G, for example with a heater, so that the Drying gas due to the heat within the interior 10a rises towards the top, or for example from a combination of fan and heater. The heating is preferably carried out ecologically in that the heat is generated using solar energy, for example in that solar collectors 20 are arranged on the roof, and the energy thus obtained is used to heat the drying gas G. Instead of a fan or in addition to the fan, a flow of drying gas G within interior space 10a can also be generated with the aid of heat, for example by heating a side wall of drying device 10 and/or the roof of drying device 10 with solar energy, and thereby Drying gas G is locally heated in such a way that a flow is formed.

FIG. 8 shows a further drying device 10 for logs 1, each log 1 having a longitudinal bore 1b, not shown, running along the entire length L of the log 1. The drying device 10 comprises a plurality of holding devices 18 for logs 1 for holding the logs 1 in a substantially vertical position, the holding devices 18 being spaced apart in the vertical direction such that at least two logs 1 can be arranged one above the other. FIG. 8 shows only three holding devices 18 as an example, with each log 1 being held by such a holding device 18 . The drying device 10 shown in FIG. 8 comprises a tower-shaped drying space 11 with an outer shell 12 open to vapor diffusion, the drying space 11 enclosing an interior space 10a. Gas-permeable intermediate floors, namely a first intermediate floor 13a, a second intermediate floor 13b and a third intermediate floor 13c, which carry the vertically extending logs 1, are arranged in the interior 10a. Adjoining the drying chamber 11, exhaust air ducts 15 are arranged at the top and air inlet ducts 14 at the bottom, in order to supply a dry drying gas G1 from below and to discharge a moistened drying gas G2 from above. The humidified drying gas G2 is fed via a line 16 to an air conditioning device 17 which at least partially removes moisture from the humidified drying gas G2 and also heats it before the dry drying gas is fed back into the drying chamber 11 . The air-conditioning device 17 also serves as an air circulation device to suck the drying gas G from the top of the inner space 10a and to supply it to the bottom of the inner space, thereby generating a vertical flow of the drying gas G in the tower-like inner space. The drying gas is usually air.

In an advantageous embodiment, the drying device 10 has a height in the range of 5 m to 30 m in order to generate a pronounced vertically directed air flow in the interior 10a.

In the drying device 10 according to FIG. 8, a so-called convection drying is preferably carried out. A drying gas flow, usually air, is generated within the drying chamber 11 with a fresh air/exhaust air flow or a circulating flow. The temperature, the flow rate and the relative humidity of the drying gas G in the drying chamber are controlled via the air conditioning device 17 . During a warm-up phase, the relative humidity is initially kept at a high level for better heat transfer, and sometimes even increased by spraying water into the drying chamber. During a subsequent drying phase, the drying gradient is then optimized depending on the type of wood. During a subsequent conditioning phase, at the end of the drying process, a moisture balance within the wood is sought.

In a preferred embodiment, the drying device 10 according to FIG. 7 or 8 also includes solar panels 20, wind generators 20 or solar cells 20 in order to operate the drying device 10 partially and preferably completely autonomously from the public power grid. A completely autonomous operation has the advantage that the drying device 10 can also be set up in areas that have no electricity supply, whereby it must be ensured that there is sufficient solar and/or wind energy available at the chosen location. In an advantageous embodiment, the drying device also includes an electrical energy store, for example a battery, to store the electricity produced by the solar cells and/or wind turbines, advantageously so that the drying process can also be continued at night without interruption. Advantageously, the drying device 10 is arranged and designed in such a way that the drying process requires less energy than the existing, produced solar and/or wind energy, or if the drying process is interrupted, that more energy is then available for the drying process than is currently being produced Amount of solar and/or wind energy, which is particularly beneficial when the amount of energy currently being produced is too low to ensure safe and/or timely drying.

FIG. 9 shows a loading device in order to be able to load logs 1 efficiently into the drying device 10 . The loading device comprises a large number of holding devices 18, in each case a log 1 running in the vertical direction can be fastened to a holding device 18. The holding devices 18 are movably arranged and are, for example, movably mounted along a rail 19 so that the logs 1 can be moved in the direction of the rail 19 and in particular can be fed to the drying device 10 or removed from it. The rail 19 could also be arranged to run above the logs 1, so that the logs 1 are, for example, suspended from carriages, with the carriages being guided by the rail 19 and being movably arranged on them in the direction of the rail 19. A plurality of rails 19 could also be provided. The loading device can be configured in a number of ways in order to move the logs 1 in the horizontal and/or vertical direction in the drying device 10 . The loading device could also comprise a plurality of holding devices 18 arranged at fixed predetermined positions and could also comprise a relocating device, for example a crane or a robotic arm, to position the logs 1 in the holding devices 18, or one log 1 from one Holding device 18 to another holding device 18 to reposition. The loading device according to FIGS. 8 and 9 could also be designed in such a way that logs 1, for example during drying, can be moved horizontally into another position within the intermediate level 13a, 13b, 13c, or that the logs can be moved vertically can be moved from one intermediate level 13a, 13b, 13c to the other, or that the logs can be moved both in the horizontal direction and in the vertical direction within the drying device 10. This is particularly advantageous for influencing the drying process of a log individually, for example to dry a log more quickly by positioning it in the lowest intermediate level 13a, in which the drying gas has a lower humidity and/or a higher temperature, or to Log to dry more slowly by positioning it on the uppermost intermediate level 13c, in which the drying gas has a higher humidity and/or a lower temperature. In an advantageous embodiment, at least some and preferably all logs 1 are provided with individual moisture sensors, so that the course of the drying process can be measured as a function of time for these logs, and if necessary the logs can be repositioned in the drying device 10 to monitor the course of the drying process with regard to a log.

In addition, in an advantageous embodiment, it is possible to supply at least one of the logs 1 with an individually heated and/or humidified drying gas G in order to flow the individual drying gas G into its longitudinal bore 1b and/or its outside 1f. In addition, it can be advantageous to arrange a heating device at least in sections in the longitudinal bore 1b, for example a hot water hose fed by solar collectors, in order to supply additional heat energy to the inner side 1e.

Figure 10 shows, by way of example, two logs 1 arranged one above the other in the vertical direction, which are arranged in such a way that their longitudinal bores 1b are mutually aligned in the vertical direction, so that the drying gas G escaping from the longitudinal bore 1b of the lower log 1 is at least partially in the longitudinal bore 1b of the log 1 arranged above it flows. Advantageously, at least some of the logs 1 are arranged so that they are mutually aligned in the drying device 10, and most or all logs 1 are particularly advantageously arranged in groups in such a way that they are aligned, for example 2, 3 or 4 logs arranged in groups one above the other, with the total possible number of logs arranged in groups one above the other Logs of the total height of the drying device 10 depends. The aligned arrangement has the advantage that the buoyancy of the drying gas G is thereby increased. As shown in Figure 10, it can also prove to be advantageous to arrange a guide element 21 between two tree trunks 1 arranged one above the other, which guide element 21 at least partially seals the space between the two tree trunks 1, and preferably seals it in an essentially airtight manner, so that the Lower log 1 escaping drying gas G is forced into the longitudinal bore 1b of the upper log 1 flow into it.

Claims (13)

1. A method for drying a log (1), wherein the log has a first and a second end face (S1, S2), an outside (1f) and an entire length (L), - By creating a longitudinal bore (1b) which extends along the entire length (L) from the first to the second end face (S1, S2), so that on the first end face (S1) an inlet opening (1c) and on the second An outlet opening (1d) is produced on the end face (S2), the longitudinal bore (1b) having an inside (1e), A drying gas (G) flows directly around both the inside (1e) and the outside (1f), so that the log (1) is dried simultaneously from the inside (1e) and from the outside (1f), characterized in that the log (1) is held in a substantially vertical position and a drying gas (G) is supplied from below the log (1) such that the drying gas (G) also flows through the longitudinal bore (1b). 2. The method according to claim 1, characterized in that the inner diameter (1g) and the length (L) of the longitudinal bore (1b) are mutually adapted in such a way that a chimney effect is generated within the longitudinal bore (1b) by the flowing drying gas (G). is, and the drying gas (G) thus within the longitudinal bore (1b) has a vertically directed flow. 3. The method according to any one of the preceding claims, characterized in that the log (1) and thus also the longitudinal bore (1b) has a length (L) of at least one meter, along which the drying gas (G) inside the longitudinal bore (1) flows upwards. 4. The method according to any one of the preceding claims, characterized in that a log (1) consisting of beech wood is dried. 5. The method according to any one of the preceding claims, characterized in that the longitudinal bore (1b) has an inner diameter in the range of 5 to 50 cm. 6. The method according to claim 4 or 5, characterized in that a relaxation cut (1a) is created along the entire length (L) of the log, which extends from the longitudinal bore (1b) to the outside (1f) of the log, and the extends from the first end face (S1) to the second end face (S2). 7. The method according to any one of the preceding claims, characterized in that a plurality of logs (1) are dried in a tower-like device (10), the logs (1) being arranged partially next to each other and partially one above the other in the vertical direction, the tower-like Device (10) is designed in such a way and the drying gas (G) is supplied in such a way that in the tower-like device (10) a substantially vertical air flow is generated. 8. The method according to claim 7, characterized in that logs (1) arranged one above the other in the vertical direction are at least partially arranged in such a way that their longitudinal bores (1b) are mutually aligned in the vertical direction, and that the out of the longitudinal bore (1b) of the lower Drying gas (G) escaping from the log (1) flows at least partially into the longitudinal bore (1b) of the log (1) arranged above it. 9. The method according to claim 7 or 8, characterized in that at least some of the logs (1) with preheated drying gas (G), in particular with individually preheated drying gas (G) flows around and / or flows through. 10. The method according to any one of the preceding claims, characterized in that the inner side (1e) of the longitudinal bore (1b) of the log (1) with a heating device (2) additional heat is supplied. 11. Wood drying device for carrying out a method for drying logs (1) according to one of claims 7 to 10, comprising a plurality of holding devices (18) for logs (1) for holding the logs (1) in a substantially vertical position, wherein the holding devices (18) are spaced apart in the vertical direction in such a way that at least two logs (1) can be arranged one above the other, and wherein the holding devices (18) are designed in such a way that an inlet opening (1c) and an outlet opening (1d) Longitudinal bore (1b) of each of the logs (1) can be kept open, characterized in that the device is designed like a tower and a drying gas (G) is supplied in such a way that an essentially vertical air flow can be generated in the tower-like device (10). is. 12. Device according to claim 11, characterized in that it has a tower-like interior space, and that an air circulation device sucks off a drying gas (G) at the top of the interior space and feeds it into the interior space at the bottom in order to generate a vertically running air flow in the tower-like interior space. 13. Device according to claim 11, characterized in that it has a height in the range of 5 m to 30 m in order to generate a pronounced vertically directed air flow inside the tower-like device (10), and that the device (10) has an inlet at the bottom (10b) for ambient air and at the top an outlet (10c) for the drying gas (G) to the ambient air.