FI123090B - Method and apparatus for drying wood and drying plant - Google Patents

Description

METHOD AND EQUIPMENT FOR DRYING TIMBER AND DRYING

The invention relates to a method according to the preamble of claim 1 and to an apparatus for drying timber according to the preamble of claim 5. The invention also relates to a drying plant comprising said apparatus.

The prior art technique for drying wood is described, for example, in the following references.

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The present invention relates in particular to the drying of saws made from small wood. Here, saws are understood to mean a wide variety of lumber that has been machined into a drying profile by sawing, planing, milling, turning or otherwise profiling like a combination of some of the above-mentioned machining methods. According to the invention, the sawdusts are dried in a bundle, without ribbing.

One of the major problems associated with drying is the deformation of the timber as the drying progresses, the survival of the wood. In small trees, the drive to deform is particularly strong and is called the juvenile problem. This is one of the reasons that has slowed down the use of small wood, for example, in the manufacture of glulam, although the raw material itself is considerably cheaper than normal sized logs. Deformation forces increase as the drying process progresses. Fresh wood is still virtually stress free. If the slender saws were dried in the traditional way, the ribs should be placed in a very dense section. Otherwise, the saws would be able to live in the gap between the ribs.

™ 25T In the prior art, reference is made in particular to Finnish Patent Publication FI 106982, which, as well as the references cited therein, are extensively described in the prior art.

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o. shortcomings in technology. In the solution described in the reference publication, drying takes place without a section. Particularly important in this is keeping the bunch of sawdust tight throughout

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§ 30 during the drying process. It is known to fill the gap between the shrinking saw blade and the surrounding container according to the shrinkage of the bundle with resiliently pneumatic actuators 2, such as fire hoses, air bags or the like. However, in practice, the resistance of the hoses at temperatures above 100 ° C has been proven to be only about one year.

There are other problems with the prior art. The formation and transfer of a bundle of sawdust, the closure of the drying space and the retention of the bundle tightly require measures that are difficult to automate and therefore require the presence of a worker.

10 Shrinkage of wood during drying requires sufficient adjustment by the clamping members. When fresh sawdust is dried, the shrinkage is of the order of 5%. For example, in a dryer such as that described in FI106982, a sawdust bundle having a diameter of about 1500 mm requires almost the entire flexibility of the surrounding 200 mm diameter hose. For a hose to have a lifetime of up to one year, it is necessary to limit the useful flexibility to about 150 mm. This means that at first the hose is almost completely flattened, and at that time the hose has a maximum clamping force. At the end of the drying process, the hose is completely circular with minimum clamping force. In the case of sawdust deformation forces, the opposite should be true. Of course, changing the pressure can reduce the problem, but this requires expensive waste management, consumes energy, and is difficult to accomplish, especially in mobile saw containers.

A very significant problem relates to the turbulence of the airflow that occurs in the areas of my bundle edge when passing the sealing area. In order to keep the drying time as short as possible, the air flow must be made as fast as possible. It is clear that a collision of air V with an approximately 150 mm wide annular barrier causes turbulence. Thus, oo has to settle for a lower flow rate than would be possible without the obstacle.

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£ Extending the drying time has a major economic impact.

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g 30 In order to keep the saws in shape during the drying process, it is also known to place o g on the stack of timber to be dried, such as concrete slabs. This procedure is suitable for 3 normal, reported lumber but worse for sawn bundles. The handling of the weights requires its own hardware and manpower. Such a solution is described in US2005223590. These structures are complex and expensive. Also, the direction of the air flow is transverse to the longitudinal direction of the saws, and it is difficult to achieve high velocity due to turbulent obstacles.

WO2006099737 discloses a press solution for eliminating deformation during saw drying. The solution is massive and expensive. Other known dryers are described in W002081992 and FI20012267.

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The invention provides a solution with several improvements to the problems of known dryers. First, the drying module according to the invention is simple in construction. From the operational point of view, there is no need for any kind of actuators attached to the removable module itself. Therefore, the drying modules can be easily and automatically moved from one drying station to another. Tank emptying and filling is simple to implement and easy to automate. The kiln of the invention has minimal handling and the entire kiln can be unmanned. The manual portion may be limited to camera surveillance.

20 No clamping / sealing element is required between the saws and the tank. The force required for the tensioning is obtained from the weight of the drying module and the sawdust, thus absolutely free. The clamping force is easily adjustable to the appropriate size. The clamping force increases spontaneously as drying progresses substantially in relation to the size of the shrinkage. Thanks to the modular design, variable size ^ 25 drying plants can be built from the same components.

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The invention is characterized by what is set forth in the appended independent claims

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£ in character sections.

§ 30 The invention will now be further described with reference to the accompanying drawings, in which:

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Figure 1 shows a drying module according to one embodiment in a loading / wooden position, viewed from the end, in a central section.

Fig. 2 shows an end view of the drying module, in the middle, in the blanks 5 in the container, during the initial drying stage.

Figure 3 shows an end view of the drying module, in the middle, during the final stage of drying.

Fig. 4 shows, in the direction of transfer of the modules of the dryer, two successive drying modules in top view, of which in module 4a the module is in the transfer position and in fig 4b the module is in the drying position connected to the air circulation system.

Figure 5 shows two other embodiments for connecting the drying module to the air recirculation piping.

The drying plant consists of several drying equipment and transfer equipment of the drying modules 3. The drying apparatus consists of a mobile drying module and a fixed 20 air recirculation, heating and humidifying apparatus. Initially, the module drying container 2 is filled with saws 1 which are in a bundle without spacers. The saws 1 are placed in the drying container 2 in the direction of the air flow and kept there throughout the drying process.

The drying module 3 has means for effecting compression between the saws 1 and the drying container 2, and means for transmitting the weight of the saws and / or substantially the drying module to a tensioning force T resisting the deformation of the saws. The deformation force of the sawdust is increased as the drying process oo progresses.

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£ The clamping force on the mechanism is caused by the gravity G applied to the carrier wheel 6

§ the counter force F, multiplied by the force x is the tightening torque. drying,

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As the g 30 advances, the saws will shrink and cover 4 will push down. Then the levers of the right-hand o g mechanism turn counterclockwise and the arm x becomes longer. Thus, the torque causing tension 5 increases as the drying progresses. In Figure 2, at the beginning of the drying, when the forces which tend to cause hydration are at their lowest, the force x1 is at its shortest. Similarly, in Figure 3, during the final stage of drying, when the forces which tend to effect hydration are at their highest, the force x2 is at its longest.

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The power transmission assembly 5 of the right side is as follows. When lowering the drying module 3, the lever 7 is initially forced to turn counterclockwise until the carrying wheel 6 has moved to the right of the vertical plane passing through the joint 8. Next, the carrying wheel 6 reaches the rail 10 and, as the descent continues, moves to the right and further rotates 10 levers 7 anticlockwise. The pivoting motion of the lever 7 is transmitted through the pivoting arm 23 of the pivoting lever 25 of the lid to the ends of the pivot lever 25, 24. The pivoting lever of the lid pivots with respect to the joint 26 and presses through the pivot 27 against the lid 1 associated with its upper end against the saws 1. When drying saws about three meters in length, the lever arms are preferably two in succession. Longer saws may have more of these. The angular positions and lengths of the levers are preferably waxed 15 so that the mechanism allows at least 5% movement of the sawtooth shrinkage, at the end of which the clamping force is increased by 10-20%.

The power transmission system 5 is preferably a parallelogram mechanism or the like.

The drying container 2 is shaped such that, when its movable portion / lid / lids 4 are retracted 20, the saws will wedge against other portions of the container wall. In relation to the wedge angle, the vertical tensioning is also transferred to the horizontal tensioning in the cross-section of the sawdust. This allows the entire sawdust to be held tight enough throughout the drying process.

Further, the drying module has transfer means 6 for moving the drying module from the previous drying station T to the next drying station. Preferably, the transfer means are known cast iron castors co that move under the guidance of the rails 10.

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□ _ § The drying module and / or the piping 11 are provided with connecting means by which the container 2

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g 30 into the air circulation system. The connecting member 15 preferably consists of an elastic o g heat-resistant material such as silicone rubber or the like. Fig. 5a shows a connection member 6, including, for example, a fluid-filled ring 20, in a depressurized state whereby the drying module can be moved to the next drying station. In Fig. 5b, the connecting member is brought into the engagement position by the action of the medium applied to the force member 20.

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In one embodiment of the invention, for connecting the drying module in the drying station to the air recirculation piping and for sealing the connection, connection and sealing is effected by means of air flow / pressure. In Fig. 5c, no air flow occurs and the connecting member is in the bypass position. In the situation of Fig. 5d, the flow of air forces 10 against the abutment surface 16 of the sealing member by the action of the bellows. At the end of the flow of air, the sealing members retract and the drying module can be unhinderedly moved to the next drying station. In another embodiment of the invention, the coupling is performed by means of an actuator, such as an air cylinder 13.

After loading, the drying module circulates through a plurality of drying stations, at which positions the drying module is connected to the air pipeline, and through each drying vessel 2 air of a suitable humidity and temperature is circulated. Finally, the blanks are discharged from the drying module. At the unloading and / or loading station, the drying module is lifted by the lifting means 18 into the air. The lifting means may, for example, be powered by 20 hydraulic cylinders 19. When the tank is lifted, the lids open automatically. Preferably, the bundle is lifted by lifting means 14 in the form of a container cross-section with reliefs 17 in the container.

Obviously, the invention is not limited to the embodiments described, but many other solutions are possible.

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Claims (10)

A method for drying timber, wherein saw blades (1) are placed for drying in a drying container (2) parallel to the air flow, and an air flow is passed through the drying container (2), characterized in that the weight of the saw blades is transmitted. Method according to Claim 1, characterized in that, in addition to the weight of the saws 10, the weight of the drying container (2) is also substantially transmitted by a clamping force against the deformation of the saws. Method according to one of the preceding claims, characterized in that, during drying, the saws (1) are forced against the walls of the container (2). 15 Method according to one of the preceding claims, characterized in that the clamping force exerted on the saw blade by one of the shell parts and / or the cover of the container is transmitted for compression between the saw blade and the other shell parts of the container. Method according to one of the preceding claims, characterized in that the deformation force of the saws is increased as the drying process proceeds. A method according to any one of the preceding claims, characterized in that g for connecting the drying module in the drying station to the air recirculation piping (11) and sealing the junction, the junction member (15) being connected and sealed by σ> 9 air flow / pressure. CO o A drying apparatus for drying timber, comprising: o a drying container (2), in which the saws (1) are arranged parallel to the air flow o 30 during drying and an apparatus for directing an air flow through the drying container (2), characterized in that the drying module (3) ) is provided with a power transmission system (5) through which the weight of the saws is transmitted to a tensioning force against the deformation of the saws (1). Drying apparatus according to Claim 7, characterized in that a force transmission system (5) is provided in the drying module, by means of which, in addition to the weight of the saws, the weight of the drying container (2) is also transmitted. Drying apparatus according to one of the preceding claims, characterized in that the drying apparatus consists of a movable drying module (3) which is connected to the air duct at the drying stations and that the drying module (3) has means for effecting compression between the saws (1) and the container. Drying plant, characterized in that the drying plant has transfer means (6) for transferring the drying module from the previous drying station to the next drying station, and that the drying plant comprises a plurality of drying apparatuses according to claims 7-9. 20 CD O O ™ 25 O) o 00 o X X Q. o o C \ J O 30 00. o CM