Patent ID: 12202168

DESCRIPTION OF THE EXEMPLIFYING EMBODIMENTS

The specific examples provided in the description given below should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given below are not exhaustive unless otherwise explicitly stated.

FIG.2illustrates schematically an example of a wood conditioning system according to an embodiment of the present invention. The wood conditioning system comprises a chamber consisting of a first chamber210and a second chamber220. The first chamber210and the second chamber220may be separated with a wall230from each other. The wall230may be implemented so that it forms at least two openings for the first chamber210. The openings are referred with A and B inFIG.2. The first chamber refers to a space into which logs115to be conditioned may be brought in e.g. by means of a trolley120. The trolley120may e.g. be configured to travel on rails. The second chamber220, in turn, may be configured to heat up an air circulated in the wood conditioning system. Concurrently, the air may also be humidified in a manner as will be described. Hence, the term ‘air’ refers to a gas compound comprising a plurality of different gases together with water vapor as well as possibly water droplets carried by the air. A direction of the circulated air in the wood conditioning system is indicated with arrows drawn with dashed lines inFIG.2. The second chamber220may also be equipped with a device240configured to provide water substantially against the direction of the circulated air.

In the embodiment of the present invention, as schematically illustrated inFIG.2, the device240providing the water is configured to spray the water through water nozzles in the second chamber220, wherein the water drips down due to nozzle velocity and an effect of gravity substantially against the circulated air. InFIG.2the direction of the water in the second chamber220is indicated with arrows directed downwards. In a preferred embodiment of the present invention the device240is configured to generate water in a form of water drops. The provided water in the second chamber220interacts with the circulated air as will be described for enabling the conditioning of the logs115and the air travels over the device240and e.g. through a droplet separator270which is configured to divert at least part of droplets from the air flow. Moreover, the separation of the droplets from the air also reduces a contamination of the water used in the system because only an optimal amount of water is conveyed, in the air, to the first chamber210wherein the water gets dirty. The air ends up to a channel through which the air may be conveyed to the first chamber210. The channel may be equipped with a number of air conveyor devices250, such as one or more fans, which are configured to generate a force for conveying the air through the wood conditioning system in response to controlling the air conveyor device250to operate accordingly. For sake of clarity, it is worthwhile to mention that the air may be input through an opening referred with A inFIG.2to the first chamber210and output through the opening referred with B from the first chamber210to the second chamber220. Hence, the air travels in the first chamber210so that a heat accumulated in the humid air transfers to the logs115brought in the first chamber210in an efficient way. In some embodiments of the invention, air conveyor devices250may be arranged to a plurality of locations within the air path. For example, at least one of the openings A or B may be equipped with the air conveyor device250, such as a fan, so that the air travels through the fan when input/output to the second chamber210/from the second chamber210. The wood conditioning system may also comprise a collection basin260for receiving at least part of the water output by the device240and for providing storage, such as in a temporal basis, for conveying the water to other entities. Moreover, the wood conditioning system200may comprise a collector140for collecting the water from the first chamber210for conveying it to cleaning device and therefrom back to the system e.g. through a heating stage. The wood conditioning system may comprise further devices and entities not shown inFIG.2.

For describing at least some aspects of the present invention in more detail it is here referred toFIG.3illustrating a non-limiting example of the device240which is configured to provide water substantially against the direction of the circulated air in the second chamber220. The device240according to the example may be implemented with a pipe310into which a plurality of nozzles320are arranged. InFIG.3only one nozzle is provided with the reference320to maintain a clarity inFIG.3. The water is input from one end of the tube310and output from the other end or alternatively it may be arranged that water is input from one end of the tube310but the other end is closed. The nozzles310may be mounted to holes processed in the tube. The number and positions of the nozzles in the embodiment ofFIG.3are non-limiting examples and they are at least in part dependent on a type of the nozzles used. In other words, different types of nozzles generate nozzle type specific spraying pattern which may have effect on the number of the nozzles and the positions of them. In an advantageous implementation of the present invention the number of nozzles and their positions are selected so that the device140is suitable for forming a uniform water spraying downwards over a cross section of the second chamber220. For example, an applicable nozzle type, in at least some application area, may be such which generate water droplets having an average diameter of 0.1-2 mm if no filling material is used in the second chamber220. If filling material is used in the second chamber220, the average diameter of the water droplets generated by the nozzles320may be larger. Generally speaking the filling material may be used for enhancing heat and humidity transfer from the water droplets to the circulated air. This is due to an increased surface area for transferring the heat and humidity, because when the water droplets collide the filling material, the droplets break to smaller droplets and at the same time the temperature gradients of the water droplets are lost which also enhances the heat and the humidity transfer. As non-limiting examples of the filling structures may be mentioned so called film-fill structure, trickle fill structure and splash-fill structure. However, any applicable structure, such as the filling is implemented with plastic pellet or pieces of tubes arranged in the chamber220. In other words, at least a part of the second chamber220may be filled with the filling material.

Furthermore, as a non-limiting example of an embodiment of the invention the water flow provided in the second chamber220may be arranged to flow at a speed of 0.2-10 m/s whereas the air flow in the second chamber220may happen at a speed of 0.5-7 m/s. The given speeds are defined with respect to a static or fixed point, or layer, in the second chamber220. With these kinds of parameters the air may be humified for the purpose of the present invention to conditioning wood.

It is worthwhile to mention that even if the implementation discussed above and as illustrated in the figures refer to that in which the device240is arranged so that it provides the water directly against the circulated air, the provision of the water may also be implemented so that at least part of the water nozzles of the device240are implemented on at least one of the walls of the second chamber220. For example, they may be implemented so that they may provide water diagonally downwards against the circulated air.

The size of the second chamber may vary according to an application area. In some embodiment the width in the cross-sectional direction ofFIG.2may e.g. be 0.5-2.5 m. However, the inventive idea does not limit the size of the second chamber anyhow in a technical sense.

As described above the operation of the wood conditioning system according to the present invention is based, at least in part, to an inventive idea how the second chamber220is implemented to operate. Namely, a temperature of the water injected, or sprayed, substantially against the circulated air is advantageously warmer than a temperature of the air. More specifically, at a surface temperature of the water droplets is warmer than the temperature of the air. Additionally, a partial pressure of water vapor, i.e. steam, on the surface of the water droplet is higher than a partial pressure of the water vapor, i.e. steam, in the air. This causes water to vaporize to the air heating the air up at the same time. As a consequence, the absolute humidity of the air may also be increased together with the increased temperature.

Further, when the humified air, i.e. water saturated air, reaches the logs115brought in in the second chamber220, the humidity of the air condensates on surfaces of the logs115from the saturated air and in that manner transfers the heat to the logs115. As a result, the water condensated on the log surface starts flowing downwards concurrently transferring heat to the logs115being in the path of the flowing water. Generally speaking, the humidity of the air in a conditioning state according to the present invention may be 100%, or at least close to that. Fundamentally thinking, the maximum temperature of the conditioning is a boiling temperature of the water under the air pressure in the chamber. In practice, the conditioning temperature is, however, below the temperature of the water provided in the second chamber220.

The described solution causes the air traveling along the stack of logs115but also a portion of air travels in gaps between the logs115in the stack. This also enhances the conditioning of the wood in the manner as described. In some embodiment of the invention the wood conditioning system may be implemented so that the logs115may be brought in in the first chamber210so that their longitudinal direction is transverse to the direction of the motion of the logs115on the trolley120. As a result, the longitudinal direction of the logs115, and, hence, the direction of the gaps, is at least partially parallel to the direction of the air flow in the first chamber210when the air is brought in through the opening A and output through the opening B. This enhances the flow of air, and, hence, the conditioning of the wood.

The flow of air through the gaps of the logs115is also enhanced due to a decrease of air volume as a result of the condensation of the water on the surfaces of the logs115. The underpressure generated in response to the decrease of the air volume especially in the gaps between the logs115may also enhance the air flow of the warmer air brought in in the first chamber210to the gaps.

As discussed above the water applied to the air in the second chamber220is advantageously warmer than the air in order to achieve the effect as described and the solution as described enables a mitigation of the drawbacks of the prior art solution. This is especially true because the temperature of the water may be maintained moderate with the present invention compared to the prior art solutions.

The present invention also enables a utilization of secondary energy obtainable from another stage of the wood processing system for heating the water output with the device240. This is possible at least in part for the reason that the water temperature may be maintained moderate, as mentioned above. For example, a drying stage of the wood processing system, e.g. in a ply or veneer manufacturing, generates air into which water is vaporized. By separating the water from the air generated at the drying stage it is possible to receive water at a temperature of 60-90 degrees Celcius (° C.) that may be directly input, and, thus, used in the wood conditioning system according to an embodiment of the present invention. In other words, the water may be input to the device240and sprayed out in the manner as described. In some embodiment of the invention the device240may be implemented so that device240comprises a plurality of sub-devices arrangeable on different vertical levels in the second chamber220. The spraying of water may also be controlled between the different levels in differing phases so that an optimal outcome may be achieved. For example, the spraying in the differing phases at the different levels mitigates an effect of temperature gradients established in the water droplets.

FIG.4illustrates schematically a portion of a wood processing system in which a wood conditioning system according to an embodiment of the present invention is applied (referred with200). The direction of motion of the logs150within the conditioning system200is indicated with the arrow. The wood conditioning system is configured to receive at least part of the water to be provided by a device240substantially against the direction of air flow from another stage of the wood manufacturing process, which may e.g. be a drying stage from which the exhaust gas is directed e.g. to so-called scrubber device410which sepa-rates at least a part of the water from the gas and the separated hot water is directed to the wood conditioning system. In some embodiment the water may be directed to the wood conditioning system through a heat exchanger420which may be arranged in the water path for controlling the temperature of the water in an optimal way. The heat exchanger420may output condensated water and take steam in from another source, such as from a boiler. At least a portion of the hot water may be temporarily stored in an applicable buffer, such as in a water storage tank. The scrubber device410may also receive the cold water from the wood conditioning system200to be heated again with the scrubber410, and also with the heat exchanger420.

FIG.5illustrates schematically a further embodiment of the present invention in which the wood conditioning system comprises a first chamber210and a second chamber220. The first chamber210has dimensions which enable a plurality of trolleys120to enter the first chamber210concurrently. In order to enable heating of the logs115in efficient manner in such an environment the second chamber220is configured with a plurality of cells510A-510E in which the heating of air in the manner as described is arranged. According to an embodiment each cell510A-510E comprise a device for generating the water droplets for dropping them down substantially against an air having a temperature less than the temperature of the water. In the embodiment as schematically illustrated inFIG.5the hot water from a scrubber, for example, is input to a cell510E, or a number of cells510D,510E, locating at the end of the first chamber210from which the logs150are transferred out from the wood conditioning system for further processing. In other words, the wood material is prepared to the next process step then. The water used water in at least one of the cells510D,510E being the latest ones in the wood conditioning system is cooled a bit, but it may be input to previous cells as indicated with references510B and510C inFIG.5. Further, the used water in cells510B and510C may still further be input to the first cell510A in the wood conditioning system200to be first used with the logs115brought in the wood conditioning system200. Finally, the circulated water may be returned to the scrubber for heating. In the described manner it is possible to circulate the water so that the logs115just brought in the wood conditioning system are conditioned with a steam being at the lowest temperature whereas the temperature of the steam increases gradually when the logs115are carried forward in the wood conditioning system. This kind of arrangement also minimizes the energy consumption of the system having a plurality of advantageous aspects in the wood product manufacturing process.

FIG.6schematically illustrates an example of a method for conditioning wood according to an embodiment of the present invention. The method may be applied in a wood conditioning system200which comprises a first chamber210and a second chamber220. In the method air is circulated between the first chamber210and the second chamber220with at least one air conveyor device250and water is sprayed substantially against a direction of the circulated air with at least one device240arranged in the second chamber220. In other words, in the method the air heated and humidified in the second chamber220may be conveyed to the first chamber210into which the wood material, such as logs, are brought in and wherein the heat and the humidity of the air is transferred at least in part in the wood material so as to achieve the conditioning. In an embodiment of the method the water may be sprayed at different levels in vertical direction of the second chamber220substantially against the direction of the circulated air. As described, at least part of the water may be received from a device external to the wood conditioning system200. Moreover, the water received from the device external to the wood conditioning system200may be heated with a secondary energy obtained from another stage of a wood processing system. The method according to the invention may further comprise a step of separating at least part of water droplets from the circulated air with a droplet separator270. The amount of separated water droplets may depend, at least in part, on a type of the droplet separator270used in the solution. As is clear from the description the method as described may be continuously applied when the wood conditioning is performed with the wood conditioning system200as described.

A further remark is herein given to the used terminology especially as it regards to that the water is sprayed substantially against the direction of the circulated air. Namely, this shall be understood also to cover any implementation in which the water and the air meet each other so that the described phenomenon occurs. In some implementation the water is sprayed against the direction of the circulated air, but the invention relates also to an implementation wherein the water is sprayed substantially to the same direction as the air circulates e.g. with a different speed. In such a case the air and the water meet so that they interact in the manner as described. Moreover, in some implementation of the present invention the system may comprise a plurality of sections into which different solutions for humidifying the air may be implemented. For example, in one section the water may be sprayed against the direction of the circulated air whereas in another section the water is sprayed in the same direction with the circulated air.

The description above provides a description of at least some aspects of the invention. It is clear that the system may comprise further elements in addition to ones described above. For example, the system is controlled with necessary control devices receiving input e.g. from a plurality of sensors. The control devices enable controlling the wood conditioning process optimally as well as any parameters and operations therein.

Generally speaking, as all the conditioning methods consume a lot of energy it is advantageous to develop solutions, like the present invention, in which at least a part of so-called secondary energy may be used for conditioning. This is possible e.g. in a veneer and ply production wherein a drying stage of the production generates an amount of the secondary energy in a form of hot water having a temperature less than the boiling point of the water at an atmospheric pressure. Hot water may also be available from other stages in the production. The present invention enables a utilization of the water binding the secondary energy in the temperature available from the production process making the present invention advantageous compared to known solutions.

The specific examples provided in the description given above should not be construed as limiting the applicability and/or the interpretation of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.