CN111819055A

CN111819055A - Dry wood board

Info

Publication number: CN111819055A
Application number: CN201980017340.6A
Authority: CN
Inventors: R·杰勒茨
Original assignee: Jaroka
Current assignee: Jaroka
Priority date: 2018-03-05
Filing date: 2019-03-05
Publication date: 2020-10-23
Also published as: EP3762196A1; BE1026071B1; BE1026071A1; WO2019170665A1

Abstract

A drying system (100) for drying wooden boards having a thickness between 1.8mm and 8mm is described. It includes: a vacuum chamber (110); a vacuum system for generating a vacuum in the vacuum chamber (110); a plurality of heat exchangers (124) located in the vacuum chamber (110), wherein each heat exchanger (110) extends in a plane, and wherein the heat exchangers (110) are configured to be in contact with the wooden board to be dried during the drying process, thereby forming a stack of alternating heat exchangers (124) and layers of wooden board to be dried. The system (100) further comprises a controller programmed for controlling the drying system (100) such that the pressure in the vacuum chamber (110) during the drying process is between 15mmHg pressure and 80mmHg pressure, the temperature is between 15 ℃ and 85 ℃, and the drying time of the drying process is between 5 minutes and 240 minutes, such as between 10 minutes and 120 minutes, such as between 10 minutes and 60 minutes.

Description

Dry wood board

Technical Field

The present invention relates generally to drying of wood panels. More particularly, the invention relates to a system and a method for rapid and efficient drying of wooden boards, wherein a thickness of the wooden board, for example between 1.8mm and 8mm, for example between 4mm and 6mm, is used as top layer.

Background

The top layer of wood is used for manufacturing parquet floors and the like. The manufacture of these top layers consists on the one hand of drying the wood and then sawing the wood into thin layers, typically between 1.8mm and 8mm thick.

The existing drying methods are air drying, dehumidifying drying and vacuum drying. In the case of air drying, a drying ratio of 1cm per year is generally achieved if the humidity percentage is to be reduced to about 14%. The percentage of waste of the dried product is about 10 to 15 percent due to the natural nature of the process with little or no process control.

When drying by dehumidification is carried out in a conventional drying chamber, a typical drying ratio is 1cm every three weeks, obtaining a waste percentage of 7%. By vacuum drying thicker wood, drying times of typically 10 to 30 days, the percentage of waste is about 3 to 4%.

Therefore, there is certainly room for improvement.

Disclosure of Invention

It is an aim of embodiments of the present invention to provide a good method and system for rapid and efficient drying of wooden boards. It preferably relates to a wooden plate having a thickness of between 1.8mm and 8mm, for example a thickness of between 4mm and 6 mm. An advantage of embodiments of the present invention is that wood may be sawn to a certain thickness and then dried.

An advantage of embodiments of the invention is that the veneer can be dried immediately after sawing the trunk.

An advantage of embodiments of the present invention is that the duration of drying can be greatly reduced, for example to less than a day, or even less than 2 hours.

An advantage of embodiments of the present invention is that less dried wood inventory is required due to the short duration of the drying process, since a specific need can be responded to more quickly. An advantage of the invention is that a great flexibility in size can be obtained. In other words, the invention has the advantage that only a limited stock is needed without having to know in advance what dimensions are needed so far for the wood to be used for producing parquet or other wood products.

An advantage of embodiments of the present invention is that, despite accelerated drying, a lower percentage of waste material can be obtained with dried wood. An advantage of at least some embodiments of the invention is that the percentage of scrap can be reduced to less than 5% scrap, for example even less than 2% scrap.

Due to the strong vacuum, the boiling point of water may be lowered, e.g. even to below 50 ℃, e.g. below 40 ℃, e.g. below 35 ℃, e.g. below 32 ℃.

An advantage of embodiments of the present invention is that a drying system and a drying method are provided which are suitable for drying a top layer for parquet manufacturing.

An advantage of embodiments of the present invention is that a system and method are provided that can dry wood panels having a thickness of 1.8mm to 8 mm. An advantage of embodiments of the present invention is that a system and method are provided that can dry wood board having a thickness of 1.8mm to 8mm to a material core. An advantage of embodiments of the invention is, inter alia, that by a good choice of the thickness of the board to be dried, heat can be transferred quickly into the core of the board.

An advantage of embodiments of the present invention is that the thermal energy may be evenly distributed over the plate.

An advantage of an embodiment of the present invention is that temperature and vacuum are controlled. An advantage of the invention is that such monitoring can be performed, for example, by continuously increasing the amount of adjustment of the energy.

An advantage of embodiments of the present invention is that drying techniques with relatively low energy consumption may be used. An advantage of embodiments of the present invention is that drying does not have to be performed by high frequency techniques with relatively high energy consumption.

This object is achieved by a product or use according to an embodiment of the invention.

The invention relates to a drying system for drying wooden boards having a thickness between 1.8mm and 8mm, the drying system comprising: a vacuum chamber; a vacuum system for creating a vacuum in the vacuum chamber; a plurality of heat exchangers located in the vacuum chamber; wherein each heat exchanger extends in a plane, and wherein the heat exchangers are configured to be in contact with the wooden board to be dried during the drying process, thereby forming a stack of alternating heat exchangers and layers of wooden boards to be dried; and a controller programmed to control the drying system such that the pressure in the vacuum chamber during the drying process is between 15mmHg pressure and 80mmHg pressure, the temperature is between 15 ℃ and 85 ℃, for example between 30 ℃ and 85 ℃, and the drying time of the drying process is between 5 minutes and 240 minutes, for example between 10 minutes and 120 minutes, for example between 10 minutes and 60 minutes.

An advantage of embodiments of the invention is that a drying process is obtained in which the typical moisture percentage of the wooden board is between 85% and 65%, for example about 80%, and in which the moisture percentage drops to a value between 6% and 10% after the drying process. During this process, the temperature may be between 15 ℃ and 85 ℃, for example between 30 ℃ and 32 ℃. The pressure during the process may be less than 40mmHg pressure, for example 35mmHg pressure or less.

An advantage of embodiments of the present invention is that the width of the wooden board may be at most 30cm or more and the length of the wooden board may be at most 300cm or more.

The drying system may be adapted to unload the wooden plates layer by layer through a rail system on which the wooden plates between the heating elements may be carried into and out of the drying oven, and where the heat exchangers may be placed in an arrangement for drying the wooden plates in the system, wherein the distance between the heat exchangers is such that contact is made with the wooden plates.

The drying system may be adapted to be able to place the heat exchangers in a first configuration for loading or unloading the wooden board in the system, the distance between the heat exchangers having a first value, and to be able to place the heat exchangers in a second configuration for drying the wooden board in the system, the distance between the heat exchangers being such as to be in contact with the wooden board.

An advantage of embodiments of the present invention is that drying by contact can be achieved, resulting in an efficient manner of drying.

The drying system may be equipped with a measuring system to check whether the heat exchanger is in contact with the wooden board in the second configuration.

An advantage of embodiments of the present invention is that contact drying can be performed for wooden boards of different thicknesses, and the system is adaptable thereto. Alternatively, the distance between the heat exchangers in the second configuration may also be set manually by a user or in an automatic manner.

The drying system may be equipped with a pressure sensor or a contact sensor to check whether the heat exchanger is in contact with the wooden board.

In a first configuration, the distance between each heat exchanger may be greater than 8 mm.

An advantage of embodiments of the present invention is that the system can be adjusted in an automatic manner or a manual manner to adjust and/or control the distance between the heat exchangers in the configuration for loading or unloading. This means that loading and unloading can always be carried out in a safe and efficient manner, regardless of the actual thickness of the wooden board.

The system may further comprise one or more measurement systems for measuring one or more of temperature, pressure or extracted water amount, wherein the one or more measurement systems form part of a feedback loop for control.

An advantage of embodiments of the present invention is that the drying process can be accurately monitored.

The controller may be adapted to dynamically vary in accordance with feedback received from the feedback loop.

An advantage of embodiments of the present invention is that the process may be performed in an automated manner, whereby the process may be performed under controlled, e.g. optimal, conditions.

The heat exchanger may be based on heating by means of hot water.

In at least one heat exchanger and preferably in a plurality or all of the heat exchangers, the different channels through which the hot water is fed may be oriented in different directions for heat transfer. Therefore, the homogeneity of the heat transferred to the wooden board can be high.

In at least one heat exchanger and preferably in a plurality or all of the heat exchangers, the different channels through which the hot water passes may be oriented in different directions for heat transfer.

The heat exchanger may be configured such that 5 or more layers, for example 9 or more layers of wooden boards, may be dried simultaneously. Alternatively, the system may be adapted to dry another number of layers of wooden boards simultaneously.

The vacuum chamber may be greater than 600mm wide, preferably 920mm or wider.

The heat exchanger may form part of a heating system that further comprises one or more of a heating source, a hot water storage vessel, piping, an accumulator, a mixing valve and a circulation pump. In some embodiments, there may be multiple connections per heating source. In some embodiments, each heating source may have 5 to 19 connections.

The vacuum system may further comprise a condenser for condensing water vapour extracted from the wooden board. The vacuum system may further comprise a discharge conduit for draining water obtained by condensing the water vapour. The discharge conduit may have a gooseneck configuration.

The invention also relates to a method of drying a wooden board having a thickness of between 1.8mm and 8mm, the method comprising: bringing the different layers of wooden boards into contact with a heat exchanger, thereby forming a stack of alternating heat exchangers and layers of wooden boards to be dried, wherein the contacting is performed in a vacuum chamber under vacuum,

the method further comprises the following steps: it is checked that the pressure in the vacuum chamber during the drying process is between 15mmHg pressure and 80mmHg pressure, the temperature is between 15 ℃ and 85 ℃, for example between 30 ℃ and 85 ℃, and the drying time of the drying process is between 5 minutes and 240 minutes, for example between 10 minutes and 120 minutes, for example between 10 minutes and 60 minutes.

The contacting is preferably performed on both sides of the wooden board. For example, for each layer of wooden board, it is preferred that the wooden board is in contact with the heat exchanger for drying both on the top side and the bottom side.

The method may further comprise a loading and unloading step in which the heat exchangers are brought into a first configuration in which the heat exchangers are spaced apart by a distance greater than the thickness of the wooden plate.

The invention also relates to a method for producing a top layer for production of, for example, parquet, wherein a wooden board is first cut to the thickness of the top layer (between 1.8mm and 8 mm) and wherein the wooden board is then dried. The method may further comprise drying according to the method described above.

The invention also relates to a controller for controlling a drying system as described above, wherein the controller is adapted to control the drying system such that the pressure in the vacuum chamber during the drying process is between 15mmHg and 80mmHg pressure, the temperature is between 15 ℃ and 85 ℃, such as between 30 ℃ and 85 ℃, and the drying time of the drying process is between 5 minutes and 240 minutes, such as between 10 minutes and 120 minutes, such as between 10 minutes and 60 minutes.

The invention also relates to a computer program product for performing the above method when the computer program product is implemented on a processor.

The invention also relates to a drying system for drying wooden boards having a thickness between 1.8mm and 8mm, the drying system comprising:

a vacuum chamber; a vacuum system for creating a vacuum in the vacuum chamber; a plurality of heat exchangers located in the vacuum chamber, wherein each heat exchanger extends in a plane, and wherein the heat exchangers are configured to be in contact with the wood panels to be dried during the drying process, thereby forming alternating heat exchangers and a stack of layers of wood panels to be dried;

the drying system is adapted to be able to place the heat exchangers in a configuration for drying wooden boards in the system, wherein the distance between the heat exchangers is such that contact is made with the wooden boards. Preferably, the contact is made on both sides of the wooden board, i.e. on both sides of the layers of wooden board.

In some embodiments, the drying system may be adapted to place the heat exchangers in a configuration for loading or unloading wooden boards in the system, wherein the distance between the heat exchangers is larger such that the heat exchangers are not in contact with the wooden boards.

In some embodiments, the drying system may be adapted to load/unload the wooden boards layer by layer in the drying system by means of a rail system.

The heat exchanger may be based on heating by means of hot water.

In at least one heat exchanger and preferably in a plurality or all of the heat exchangers, the different channels through which the hot water is fed may be oriented in different directions for heat transfer.

Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims and features of other dependent claims as appropriate and not merely as explicitly set out in the claims.

The above and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.

Drawings

Fig. 1 shows a schematic overview of a heating system according to an embodiment of the invention.

Fig. 2 shows an example of a vacuum chamber of a heating system according to an embodiment of the invention.

Fig. 3 is a schematic view of a stack of heat exchangers and wooden decks in a configuration for loading and unloading wooden boards and in a configuration for drying wooden boards as used in an embodiment of the invention.

FIG. 4 is a schematic view of a collector for a heat exchanger used in an embodiment of the present invention.

The drawings are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes.

Any reference signs in the claims shall not be construed as limiting the scope. The same reference numbers in different drawings identify the same or similar elements.

Detailed Description

Although the present invention will be described with respect to particular embodiments and with reference to certain drawings, the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and relative dimensions do not necessarily correspond to the actual reductions required to practice the invention.

Furthermore, the terms "first," "second," and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

Furthermore, the terms "top," "bottom," "over," "front," and the like in the description and in the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

It is to be noticed that the term 'comprising', used in the claims, should not be interpreted as being restricted to the means listed thereafter, but does not exclude other elements or steps. It should therefore be interpreted as specifying the presence of the stated features, values, steps or components as referred to, but does not preclude the presence or addition of one or more other features, values, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising the devices a and B" should not be limited to devices consisting of only the components a and B. It is shown that the only relevant components of the device with respect to the present invention are a and B.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Moreover, although some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are intended to be within the scope of the invention and form different embodiments, as will be understood by those of skill in the art. For example, in the following claims, any of the claimed embodiments may be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

In an embodiment of the invention, reference is made to a drying system, to a drying system for wood panels. "Wood-based panel" refers to a wood-based panel such as those that may be typically used as a top layer of a wood product. Thus, the thickness of the wooden plate is between 1.8mm and 8mm, for example between 4mm and 6 mm. A typical advantage of this is that it can be used as a wooden board for the top layer of parquet. The kind of wood is not limited for the present invention. The kind of wood may be, for example, oak, beech, etc., but the invention is not limited thereto, but may in principle be used for all kinds of wood.

In a first aspect, the invention relates to a drying system for drying wooden boards having a thickness between 1.8mm and 8 mm. The drying system is based on contact drying in vacuum. The drying system includes a vacuum chamber and a vacuum system for creating a vacuum in the vacuum chamber. It further comprises a plurality of heat exchangers located in the vacuum chamber, wherein each heat exchanger extends in a plane, and wherein the heat exchangers are configured to be in contact with the wooden boards to be dried during the drying process, thereby forming a stack of alternating heat exchangers and wooden board layers to be dried. The drying system further comprises a controller programmed to control the drying system such that the pressure in the vacuum chamber during the drying process is between 15mmHg pressure and 80mmHg pressure, the temperature is between 15 ℃ and 85 ℃, for example between 30 ℃ and 85 ℃, and the drying time of the drying process is between 5 minutes and 240 minutes, for example between 10 minutes and 120 minutes, for example between 10 minutes and 60 minutes.

The standard and optional components will be further described with reference to the exemplary drying system as schematically shown in fig. 1 and 2. The exemplary drying system 100 as shown in fig. 1 includes: a vacuum chamber 110, also referred to as a "vacuum drying chamber"; a heating system with a heat source 120, such as a heat pump, connected to a heat exchanger 124 through a collector 122 for supply and exhaust; and a vacuum system including a vacuum pump 130, a condenser 132, and a reservoir 134. The system also typically includes a control panel for operating the system. It should be noted that embodiments of the present invention are not so limited, and rather, the exemplary drying system is merely illustrative of one particular example.

The drying system comprises a vacuum chamber in which the wooden board is dried. In this example, the vacuum chamber has an elongated cylindrical shape or a rectangular shape. However, it should be noted that the particular shape of the chamber is not limiting and other forms may be used. The cylindrical shape has the advantage that, for example, there are relatively few corners and edges to facilitate the gas-tight sealing of the vacuum chamber. The rectangular shape has, for example, the advantage that the capacity of the wood that can be dried can be optimized. The vacuum chamber must be capable of being completely sealed in a gas-tight manner. For this purpose, suitable vacuum seals may be provided at the locations where the different parts of the vacuum chamber are in contact with each other when closed, and at the locations where there are coupling ducts. This means that the chamber must be able to withstand air pressure from the outside. The vacuum chamber in the present example is made of stainless steel, but other materials may be used as long as they can withstand the air pressure. In this example, the uppermost part of the cylinder may be open. Various openings are provided in the vacuum chamber to provide the necessary connections to other components. First, in the present example, an opening is provided for connection to a vacuum pump. In the present example, two openings are provided for connection with a vacuum pump, but this may also be a different number. Secondly, there is also an opening for the pipe of the heating device. The size of the vacuum chamber can be adjusted according to the desired application and capacity.

The system also includes a vacuum pump for creating a vacuum in the vacuum chamber. The required performance of the vacuum pump is to achieve a vacuum of 30mmHg within the vacuum chamber. The amount of water vapor remaining after condensation determines the required capacity of the vacuum pump. If, for example, no condensation has occurred, the vacuum pump should be capable of approximately 560m cylinder chamber removal in this example over a period of time, for example, between 25 minutes and 1 hour³Water vapor, removal of 3800m for rectangular chamber³Water vapor. As previously mentioned, it should be noted that the content may be adjusted according to the desired application and capacity. Condensation is very important and a critical point, since large amounts of water vapor have to be converted. Preferably, the vacuum pump is selected such that the portion of the pump that is in contact with the water vapour is corrosion resistant, since the water vapour contains tannins (corrosive), which otherwise would adversely affect the life of the vacuum pump. Suitable vacuum pump systems may be based on diffusion pumps, rotary pumps, water ring vacuum pumps, and the like.

The system is adapted to convert the removed water vapor to water. In the present example, a condenser is used for this purpose. In the present exemplary system, the water obtained after condensing the water vapor in the condenser is directed in a conduit by gravity towards a vacuum pump. However, a gooseneck was placed in the line from the condenser to the vacuum pump. At the last point of the gooseneck, a drain pipe is placed to drain the water accumulated in the gooseneck under the influence of gravity. In this example, this water is also collected in a reservoir and a quantity is measured to determine the rate and state of drying. The water may then be drained, for example after adjusting the pH to a neutral pH level. It should be noted that other embodiments for achieving the venting of water vapor converted to water may also be used. In some embodiments, the water vapor may also be vented directly, but this makes it less easy to control the amount of moisture extracted from the wood board.

In the present example, all the pipes for the vacuum section are made of thick walled PVC pipe, the wall thickness of which is for example 3 to 4 mm. However, it is noted that other materials may also be used. The diameter of the pipe from the vacuum chamber to the condenser is of sufficient size. The pipe diameter from the gooseneck to the part where the water is collected is small but sufficiently large. All connections are airtight and glued well.

The drying system also includes a heating system. In the present example, the heating is based on heating by means of hot water technology, but embodiments of the present invention are not limited thereto. Alternative heating systems are for example by means of thermal oil, electricity, high frequency, etc. In the present example, in case the heating is based on heating by means of hot water technology, the heating system comprises a heating source, a hot water storage container and one or more heat exchangers. Furthermore, in the present example, a mixing valve, a circulation pump and the necessary piping and accumulators are also provided. The temperature of the water to be circulated is between about 15 ℃ and 85 ℃, for example between 30 ℃ and 75 ℃.

The heating source in this example is a heating boiler. The heating boiler is for example a condensing boiler with sufficient capacity. Which produces hot water that flows via a pipe to a hot water collection tank. The hot water collection tank is a reservoir that ensures that the required hot water is available to feed the heat exchanger in the vacuum chamber. The supply is usually done by means of a circulation pump. In this example, the hot water collection vessel is also a reservoir into which water flows from the heat exchanger after use. Typically, the collection vessel is well insulated and therefore there is no heat loss.

The one or more heat exchangers ensure heat exchange with the wooden board. In one example, as used in this example, the heat exchanger or exchangers consist of a number of tubes, for example eighteen rectangular channels of aluminium 30mm by 25mm in diameter, 7.5mm to 20mm in wall thickness and 3000mm long in length in the vacuum chamber. In this example, the tubes are adjacent to each other and are wrapped in a gusset, such as an aluminum gusset. The supply of these heat exchangers is done by each collector, which ensures the distribution of hot water for each heat exchanger. For example, each heat exchanger may be fed via a collector. In this example, each heat exchanger extends substantially in a plane. One advantage to uniformly drying wood is that the temperature is the same throughout the heat exchanger. Therefore, the heat is preferably distributed as evenly as possible. The energy released by the heat exchanger must also be sufficient to transfer the required energy in a quantitative manner. During the drying process, different heat exchangers are placed one above the other, with wooden plates placed between them each time they are stacked. It is important that the wooden plate and the heat exchanger are in good contact with each other. In order to be able to load and unload wood between the heat exchangers, different techniques can be used. In one example, a system is provided for systematically unloading the different layers of wood by moving the various heat exchangers layer by layer out of the drying chamber (e.g. sliding them) and removing the plates therefrom. This can be done, for example, by means of a rail system. In another example, the dried/to-be-dried wood is systematically removed layer by layer from the system while the heat exchanger remains in the drying chamber. In some embodiments, a system is installed in which more space is created between the heat exchangers during loading and unloading in some embodiments. After loading, it must also be possible to close the opening again in order to bring the heat exchanger closer together again in order to come into contact with the wooden board that must be dried. In each system, care is taken to have contact between the heat exchanger and the wood, as this ensures an efficient drying process. During the drying process, the heat exchangers may be placed at a fixed distance from each other for drying. However, in some embodiments, contact sensors or pressure sensors may also be used to place the heat exchangers closer together until good contact is obtained between the heat exchangers and the wooden plates. For example, a possible configuration of the heat exchanger and the wooden board during the drying process (a) and during loading and unloading (B) is shown in fig. 3.

In the present exemplary system, heating is achieved by circulating water through aluminum panels with channels during the drying process, the temperature of which is between 15 ℃ and 85 ℃, for example between 30 ℃ and 85 ℃. In the heat exchanger, the water may circulate in different directions. By using heat exchangers with channels in different directions, a more homogeneous heat distribution can take place and the heat transfer can be as uniform as possible. In this way, there is no cold spot. Preferably, the temperature difference in the water in the heat exchanger is at most 1 ℃.

The heating system of this example also includes a mixing valve to selectively mix the heated water flowing into the heat exchanger in the vacuum chamber with the return water from the heat exchanger to achieve a desired supply temperature. The mixing valve may be part of the hot water control device and controlled by a central control system.

For circulation, in one specific example, the capacity of the circulation pump is set at 10m³Hour to 100m³Between/hour, e.g. ofLess than 18m³Per hour or for example at least 35m³In terms of hours. Preferably, the resistance provided by the circuit is minimized. When the resistance is too large, the capacity of the pump may decrease.

In this example, heated water exits the boiler via a pipe to a vacuum chamber where it passes into a collector. The collector distributes the water further to a heat exchanger (also referred to as a "heating element"). The collector ensures that each pipe of the heat exchanger receives the same amount of hot water and that as much water as possible can be discharged. The tubing and the collector in the present example are composed of stainless material. The conduit is preferably provided with sufficient shut-off valves so that a circuit can be formed. As mentioned before, it is important to create as little resistance as possible in the pipe. This can be done by choosing a sufficiently large pipe diameter. The connection between the collector to the heat exchanger and the outlet of the heat exchanger must be flexible, since it must be possible to place the heat exchangers mechanically far from and close to each other as described above. Thus, the input and output connections between the collector and the heat exchangers are flexible, so that the heat exchangers can be adjusted in height relative to each other. An example of a collector is shown in fig. 4.

In the present example, a central controller is also provided. The controller ensures that control can be performed according to the input drying program. Furthermore, a central controller may be provided to collect information about the drying process. The purpose of collecting the data is to obtain information about the drying process and to check it. Control may be accomplished locally or remotely over a network, such as over the internet. Maintenance planning and troubleshooting may also be provided in the controller.

Measurement and monitoring equipment should also be provided in the system to collect data and compare it to the required parameters and make the necessary adjustments as required. The desired parameters include the wood temperature and the set point of the pressure in the drying chamber. The measurement and monitoring device may for example comprise one or more of: temperature sensors, software packages, control valves and their controllers, vacuum gauges, measuring cups (for water amounts), timers and flow meters. In some embodiments, the wood may also be inspected before and/or after drying. This may be done automatically or manually. The measuring and control device may be adapted for this purpose. Alternatively, the results may be input directly into the controller. Before this, the quality of the wood can be checked to determine a drying plan. After that, the weight of the wood can be checked for quality control.

In a second aspect, the present invention relates to a method for drying a wooden board. The method may be performed in a preferred manner in a system as described in the first aspect, but this is not essential.

The method comprises the following steps: several layers of wooden plates with a thickness of 1.8mm to 8mm are brought into contact with a heat exchanger, which contact takes place in a vacuum chamber in a vacuum, in order to form a stack of alternating heat exchangers and wooden plate layers to be dried. The method further comprises the following steps: it is checked that the pressure in the vacuum chamber during the drying process is between 15mmHg pressure and 80mmHg pressure, the temperature is between 15 ℃ and 85 ℃, for example between 30 ℃ and 85 ℃, and the drying time of the drying process is between 5 minutes and 240 minutes, for example between 10 minutes and 120 minutes, for example between 10 minutes and 60 minutes. The method may further comprise a loading and unloading step in which the heat exchangers are brought into a first configuration in which the heat exchangers are spaced apart by a distance greater than the thickness of the wooden plate. After the step of loading the wooden deck, bringing the wooden decks into contact with the heat exchanger by bringing the heat exchangers closer together.

Other standard and optional steps of the method may correspond to the function of the elements of the drying system described in the first aspect.

In a third aspect, the present invention relates to a controller for controlling a drying system as described in the first aspect. The controller is adapted to control the drying system such that the pressure in the vacuum chamber during the drying process is between 15mmHg pressure and 80mmHg pressure, the temperature is between 15 ℃ and 85 ℃, for example between 30 ℃ and 85 ℃, and the drying time of the drying process is between 5 minutes and 240 minutes, for example between 10 minutes and 120 minutes, for example between 10 minutes and 60 minutes. The controller may be automated and may be based on feedback from a measurement system for measuring process parameters in the drying system. The controller may be programmed according to a predetermined algorithm. The controller may be implemented by means of a processor coupled to a memory subsystem comprising at least one form of memory. A storage subsystem may be provided. In certain embodiments, the display system, keyboard, and pointing device may be provided as part of a user interface subsystem by which a user may manually output information. There may also be ports for input and output of data, e.g. for communication with a feedback system. The various elements of the processing system are coupled in different ways, such as by a bus subsystem. The invention therefore also relates to a computer implemented controller adapted to perform the method steps of the exemplary embodiments described above. Thus, the various steps may also be included as software in a processing system.

The invention also includes a computer program product which, when executed on a computer device, provides the functionality of each of the methods of the invention. Furthermore, the invention comprises an information carrier, such as a CD-ROM, DVD-ROM or floppy disk, storing a computer product in machine-readable form, which when run on a computer device performs at least one method of the invention. Today, such software is typically downloaded via the internet or a corporate intranet site, whereby the invention comprises the transmission of a computer product according to the invention via a local or wide area network.

The various aspects can be easily combined with each other, so that these combinations also correspond to embodiments according to the invention.

Claims

1. A drying system (100) for drying wooden boards, the wooden boards having a thickness of between 1.8mm and 8mm, the drying system comprising:

-a vacuum chamber (110);

-a vacuum system for generating a vacuum in the vacuum chamber (110);

-a plurality of heat exchangers (124) located in the vacuum chamber (110), wherein each heat exchanger (124) extends in a plane, and wherein the heat exchangers (124) are configured to be in contact with the wooden board to be dried during the drying process, thereby forming a stack of alternating heat exchangers (124) and layers of wooden board to be dried;

-a controller programmed for controlling the drying system (100) such that the pressure in the vacuum chamber during a drying process is between 15mmHg pressure and 80mmHg pressure, the temperature is between 15 ℃ and 85 ℃, and the drying time of the drying process is between 5 minutes and 240 minutes, such as between 10 minutes and 120 minutes, such as between 10 minutes and 60 minutes.

2. Drying system (100) according to the preceding claim, wherein the drying system (100) is provided with a measuring system to check whether the heat exchanger (124) is in contact with a wooden board.

3. Drying system (100) according to the previous claim, characterised in that the drying system (100) is provided with a pressure sensor or a contact sensor to check whether the heat exchanger (124) is in contact with a wooden board.

4. Drying system (100) according to any of the preceding claims, wherein the drying system (100) further comprises one or more measurement systems for measuring one or more of temperature, pressure or amount of extracted water, wherein the one or more measurement systems are part of a feedback loop for control.

5. Drying system (100) according to the preceding claim, wherein the controller is adapted to dynamically vary based on feedback received from the feedback loop.

6. Drying system (100) according to any of the preceding claims, wherein the heat exchanger (124) is based on heating by means of hot water.

7. Drying system (100) according to the previous claim, wherein in at least one of said heat exchangers (124) and preferably in a plurality or all of said heat exchangers (124) the hot water is oriented in different directions for different channels through which the heat is transferred.

8. Drying system (100) according to any of claims 6 to 7, characterised in that in at least one of the heat exchangers (124) and preferably in a plurality or all of the heat exchangers (124), the different channels through which the hot water is passed for transferring heat are directly supplied by a common collector.

9. Drying system (100) according to any of the preceding claims, wherein the drying system (100) is adapted to transport a stack of entire heat exchangers (124) into and out of the vacuum chamber (110) by means of a cart rail system with wooden plates between the heat exchangers.

10. Drying system (100) according to any of the preceding claims, wherein the drying system (100) is adapted to be able to place the heat exchangers (124) in a first configuration for loading or unloading wooden boards in the system, the distance between the heat exchangers (124) having a first value larger than 8mm, and to be able to place the heat exchangers (124) in a second configuration for drying wooden boards in the system, the distance between the heat exchangers (124) being such as to be in contact with wooden boards.

11. Drying system (100) according to any of the preceding claims, wherein the heat exchanger (124) is configured such that at least 5 layers of wooden boards, such as at least 14 layers of wooden boards, can be dried simultaneously.

12. Drying system (100) according to any of the preceding claims, wherein the width of the vacuum chamber (110) is larger than 600mm, preferably 920mm or wider.

13. Drying system (100) according to any of the preceding claims, wherein the heat exchanger (124) forms part of a heating system, the heating system further comprising one or more of a heating source (120), a hot water storage vessel, piping, a collector, a mixing valve and a circulation pump.

14. Drying system (100) according to any of the preceding claims, wherein the vacuum system further comprises a condenser for condensing water vapour extracted from the wooden board.

15. Drying system (100) according to the previous claim, characterised in that said vacuum system further comprises a discharge duct for draining the water obtained by condensation of the water vapour.

16. Drying system (100) according to the previous claim, wherein the discharge duct comprises a gooseneck configuration.

17. A method for drying a wooden board having a thickness of between 1.8mm and 8mm, the method comprising:

-contacting the plurality of layers of wooden boards with a heat exchanger (124) thereby forming a stack of alternating heat exchangers (124) and layers of wooden boards to be dried;

wherein the contacting occurs in a vacuum chamber (110) under vacuum;

the method further comprises the following steps: it is checked that the pressure in the vacuum chamber during the drying process is between 15mmHg pressure and 80mmHg pressure, the temperature is between 15 ℃ and 85 ℃, and the drying time of the drying process is between 5 minutes and 240 minutes, such as between 10 minutes and 120 minutes, such as between 10 minutes and 60 minutes.

18. The method of claim 17, wherein the contacting occurs on both sides of the wooden board simultaneously.

19. A controller for controlling the drying system (100) according to any of claims 1-16, wherein the controller is adapted to control the drying system (100) such that during a drying process the pressure in the vacuum chamber is between 15mmHg and 80mmHg pressure, the temperature is between 15 ℃ and 85 ℃, and the drying time of the drying process is between 5 minutes and 240 minutes, such as between 10 minutes and 120 minutes, such as between 10 minutes and 60 minutes.

20. A computer program product for performing the method according to any one of claims 17 to 18 when the computer program product is implemented on a processor.

21. A drying system (100) for drying wooden boards, the wooden boards having a thickness of between 1.8mm and 8mm, the drying system (100) comprising:

-a vacuum chamber (110);

-a vacuum system for generating a vacuum in the vacuum chamber (110);

-a plurality of heat exchangers (124) located in the vacuum chamber, wherein each heat exchanger (124) extends in a plane, and wherein the heat exchangers (124) are configured to be in contact with the wooden board to be dried during the drying process, thereby forming a stack of alternating heat exchangers (124) and layers of wooden board to be dried;

the drying system (100) is adapted to enable placing the heat exchangers (124) in a configuration for drying wooden boards in the system, wherein the distance between the heat exchangers (124) is such that contact is made with the wooden boards.

22. Drying system (100) according to claim 21, wherein the arrangement is adapted to provide contact between the heat exchanger (124) and a wooden board on both sides of the wooden board during drying.

23. Drying system (100) according to any of claims 21-22, wherein the drying system (100) is adapted to place the heat exchangers (124) in a configuration for loading or unloading wooden boards in the system, wherein the distance between the heat exchangers (124) is larger than in the configuration for drying, such that the heat exchangers (124) are not in contact with wooden boards.

24. Drying system (100) according to any of claims 21 to 23, wherein the drying system (100) is adapted for loading/unloading wooden boards layer by layer in the drying system (100) by means of a rail system.

25. Drying system (100) according to any of claims 21-23, wherein the heat exchanger (124) is based on heating by means of hot water.

26. Drying system (100) according to the previous claim, wherein in at least one of said heat exchangers (124) and preferably in a plurality or all of said heat exchangers (124) the hot water is oriented in different directions for different channels through which the heat is transferred.

27. Drying system (100) according to any of claims 21 to 26, characterised in that in at least one of the heat exchangers (124) and preferably in a plurality or all of the heat exchangers (124), the different channels through which the hot water is passed for transferring heat are directly supplied by a common collector.

28. A method for producing a top layer, for example for parquet flooring, wherein a wooden board is first sawn to a thickness between 1.8mm and 8mm and then dried.

29. The method of claim 28, wherein the drying is accomplished by the method of claims 17-18.