Improvement Made in the Vacuum Wood Drying Kiln that Dries the Wood By Means of the highest frequency (Microwave) Electromagnetic Wave Energy

The invention relates to the improvement made in the vacuum wood drying kilns that dry the wood placed into the same using the highest frequency (microwave) electromagnetic wave energy.

The vacuum wood drying kilns, which perform the drying process for the wood using the electromagnetic wave energy, are already known. Concerning said type of kilns, there is present the document no. U2113666 for which the patent application was previously made. As in the invention being the subject matter of the present application, the electromagnetic wave energy is applied to the wood desired to be dried also in said kiln according to this prior document. In said kiln, a cylindrical structure is mentioned and there is present a round table, on which the wood to be dried is placed, at an interior space called the chamber, wherein after the wood is placed on this round table, the wave is applied downwards from the top on the wood, from an electromagnetic wave source. During said wave application, the round table is swiveled and the drying process is terminated, after which the dried wood is conveyed from said table to the outside. However, the drying kiln mentioned in said document has a low drying capacity and it is capable of drying a small amount of wood. Further, since it has a small size, it requires that the wood to be placed into the same be cut according to a short length, and is not able to dry the big sized wood. Because it is capable of achieving only a low capacity of drying, more energy is required to be consumed in order to dry the desired quantity of wood. Moreover, during the drying process performed using said kiln, the back reflection of the wave energy applied on the lumber or the log is possible, which in turn leads to the accumulation and the cessation of the waves on the transmitter antennas. Said shortcoming is observed particularly in the systems in which each of the n high frequency generators is individually connected with the antennas that open within the machine.

Another document that belongs to the prior art relates to the wood drying kiln, which performs the drying process utilizing the electromagnetic wave energy as mentioned in the patent document no. RU2115073. In said kiln, there are present the antennas emitting the electromagnetic waves, in a quantity that is half the number of the high frequency generators; and at least one indicator and detector opening into the machine. According to the technical approach employed in said drying kiln, the rays impinge upon the lumbers by a certain angle and as a result, the rays are reflected back and turn towards the transmitter antennas. Each high generator outlet available within said kiln is connected with a generator antenna. With the positioning of said antennas on a horizontal plane inside the machine, the wood that is aimed to be dried forms an angle from 45 degrees up to 75 degrees on the wall of the machine. In this way, the kinematic connection and the synchronous electrical drive are formed. On the other hand, the high energy cost occurs also in the drying kilns mentioned in said document. Because of the inability to diffuse the dielectric radiation in a uniform manner inside the lumber, along the length of the lumber, the difficulty is encountered in regulating the diffusion of the rays with a certain angle (Byruster angle) over the lumber. The inability to regulate, according to a certain angle, the rays being used causes the formation of cracks in the wood to be dried. During the drying process, a portion of the lumbers is discarded in a way not allowing any sort of utilization, hence the losses are encountered in the production.

Another drying machine, which performs the drying process by means of the electromagnetic wave energy as in our invention being the subject matter of the present application is the kiln mentioned in the document no. RU2057404. Said drying kiln comprises the antennas manufactured from a single piece, with high frequency generator opening into the machine and said antennas transmitting the electromagnetic waves, positioned in the form of a chess arrangement. However, the electromagnetic waves emitted from the antennas are not able to diffuse in a certain direction. Since the antennas in this kiln are manufactured from a single piece, a structure that is thicker or thinner than is necessary forms during the manufacture in the windows present on the antenna, for such reasons as bending and welding. Consequently, the distances between the windows present on the antenna vary, which in turn prevents the effective diffusion of the electromagnetic waves to be applied on the wood and reduces the quality of the drying process. Further, the window intervals and the windows' own parameters are arranged in a random manner on the antennas in this type of drying kilns. What is aimed here is to simply enable the expelling of the electromagnetic wave as soon as possible. As a result, the electromagnetic waves may not be applied in an effective manner on the wood desired to be dried.

In addition, since there are two or more main diffusers in said drying kilns, they prevent the wave intensity that is being applied on the wood to be dried from reaching the desired value, cause the increase in the leakages, and lead to the formation of the losses in the electromagnetic wave being applied. For these reasons, it takes longer to complete the wood drying process, and more energy is consumed to accomplish the drying process. Moreover, the use of more than one main diffusers accordingly increases the number of antennas connected to said diffusers.

In the existing kilns, the air that forms inside the chamber during the drying process is either sucked by a ventilator device located within the chamber, by way of vacuum application from a single point, or sucked by a vacuum device located outside the chamber, by way of vacuum application, thus said air inside the chamber is discharged. In both methods, it takes very long to suck the air inside the chamber and also it is not possible to perform the suction with sufficient efficiency; hence the air inside the chamber is not able to be completely discharged. In case the air inside the chamber is not able to be fully discharged in an appropriate and rapid manner, deviations occur during the application of the electromagnetic waves on the wood to be dried, and some of the electromagnetic waves may reach the wood only with a lost intensity. This extends the drying time for the wood and causes more energy to be consumed for a complete drying. When the air inside the chamber may not be fully discharged, the water molecules present within the wood desired to be dried have difficulty in moving outside from the inner part of the wood, thus affecting the drying quality.

When the air inside the drying kiln is fully drawn, the pressure of the liquid on the interior of the wood increases. When the air is absent in the external ambience, the water molecules inside the wood move from the high pressure within the wood towards the low pressure outside the wood, thus the water molecules inside the wood begin to move outside of the wood in the form of liquid and vapor. In case a good vacuum application is performed, both the time for the drying process is shortened and the quality is increased for the dried wood.

In the drying kilns according to the prior art, the temperature at the interior of the chamber is raised up to 100 degrees, to enable the water within the chamber to evaporate. The water vapor that rises upon the evaporation of the water within the chamber moves towards the top section of the chamber and converts into water droplets on the ceiling. As these water droplets drop back on the dried wood towards the end of the drying, they both influence the quality of the drying process and cause the moisture to form again inside the chamber.

In the drying kilns according to the prior art, the water emerging out of the wood to be dried is accumulated at the bottom of the chamber, in the lower section of the table on which the wood subjected to drying are present. The presence, in the lower section, of the water that emerges out of the wood during the drying process causes the interior to have a moist ambience. The water removed from the wood and accumulated at the bottom of the chamber is discharged after the drying process has been complete and the dried wood has been taken out of the chamber. Said water flows outside and wets the surroundings upon the opening of the chamber door at the end of the drying process. It becomes necessary to employ workers to dry the interior and the exterior of the machine following every drying process, leading to an unnecessary labor and work loss. The kiln may not be operated during the period when the water inside the chamber is being evacuated and it is not possible to conduct a serial drying process.

Since the wood is heated inwards beginning from the outside in the drying processes according to the prior systems, first the bark part dries and the water pressure inside the wood causes the formation of cracks on the bark part of the wood as it seeks a way to go out. The cracked portions are cut and removed at the end of the drying process.

In our invention according to the present application, improvements have been provided in order to eliminate the aforesaid technical problems with the kilns that perform the wood drying process by the use of the electromagnetic wave energy.

First of such improvements made is the manufacture of the antennas in a manner in which certain parts are joined together, instead of manufacture from a single piece. The reason for manufacturing the antenna in a piecewise manner is that in case it is manufactured as a single piece, the distances between the windows on the antenna would vary during the bending and welding in case of occurrence of a quick melting and thus it would not be possible to have precise window intervals. The variation in the nearness of the windows negatively impacts the diffusion of the electromagnetic waves. On the other hand, a piecewise approach for the manufacture increases the care being paid to the manufacture of the antenna piece and enables to avoid the manufacturing defects.

Until today, the window intervals and the windows' own parameters on the antennas have been considered in a random manner, as long as the electromagnetic wave has been able to be expelled from the windows. However, in the kiln according to the invention, the ratio of emergence of the electromagnetic wave from all the windows on the antenna has been taken into account, in order to provide an effective reflection of the waves. Said emergence ratios are adjusted by means of a wave measuring device (oscillograph), and as a result, the most ideal window sizes are attained and the windows with such ideal ratios are opened on the antennas. Windows are the components that are given the highest consideration during the manufacture of the antennas. In case the determined parameters are not taken into account, the drying for the wood is not achieved in desired quality, and a check measurement made by a hygrometer device on various zones of the dried wood reveals that said zones have differing moisture contents.

In our wood drying kiln according to the application, there is present a single main diffuser antenna. The presence of a single main diffuser antenna minimizes the leakage problem, as well as providing the wave intensity that is required to enable the wood to be dried in a shorter period of time, owing to the provision of all the waves to the antennas from said single main diffuser. In our wood drying kiln according to the application, the connections for the antennas, which are manufactured by way of joining certain pieces, are provided with the help of the flanges. Flanges are made of 10 mm thick aluminum AMS.

The single main diffuser antenna used in our wood drying kiln according to the application has a structure in the form of an inverted T. The inverted T form of the main diffuser antenna enables all the waves coming from the electromagnetic generator to be collected in a single piece. Said collection in a single piece enables a possible leakage to take place at a single location, thus reducing the leakage.

In the main diffuser antenna of our kiln according to the application, a total of 4 right and left side antennas are located on the horizontal plane inside the machine. The reduction in the number of antennas enables the wave to move together in a more intense manner. The special structure of the windows on the antennas enables the effective use of this intensity.

In our invention being the subject matter of the application, for the purpose of providing the air-free ambience required for the drying machine, there are present the aeration pipes, which extend into the chamber and suck the air through the plurality of the holes they carry to collect said air and move it outside. Owing to said perforated aeration pipes, the air inside the chamber is not sucked and collected from a single center, which was the case with the drying kilns according to the prior art. Instead, the air may be sucked and collected at many points inside the chamber in the zones through which the aeration pipes pass within said chamber. By way of conveying the air inside the chamber in a faster manner towards the outside thereof, our machine according to the application is enabled to operate in a more effective manner. Thus, the technical problems with the kilns according to the prior art resulting from the inability to expel the air inside the chamber to a desired extent are eliminated.

In our kiln according to the application, in order to resolve the problem that the water droplets, which are formed on the ceiling of the chamber as a result of the temperature of the air inside the chamber rising up to 100 degrees, drip back on the dried wood towards the end of the drying process in the drying kilns according to the prior art, the copper pipes are added to the sections where the water vapor moves towards the upper part of the chamber. Said copper pipes enable the condensate to ^* be absorbed faster, condensing and taking up the same, and they expel the water vapor taken up from the interior of the chamber. Owing to said improvement, the problem with the water droplets dripping on the dried wood during or at the end of the drying process is eliminated; hence the drying process with better quality is able to be performed.

In addition, all the processes of our kiln according to the invention are based upon the automation. Because all the equipment related with the kiln are connected to the automation feature, all the operating principles may be monitored by means of automation, and it becomes possible to take immediate action in case of any failure or in any unusual case likely to be encountered during the drying process. Owing to said automation feature; the monitoring work for the equipment, power supply, high frequency source and operation may be performed in a computer environment. As this will reduce the number of workers to be employed during the operation of the kiln, the operating costs are accordingly reduced.

In our invention being the subject matter of the application, a water channel is opened on the bottom of the chamber, in order to drain the water emerging from the wood during the drying process. The water emerging from the wood during the drying process is discharged by means of said water channel opened; hence no need being left to spend labor for draining the water inside the machine after the drying process and to employ workers for this purpose. There is also no need to keep the machine in standby position in order to feed into the machine the subsequent wood to be dried. As a result, our kiln according to the application provides the ability to operate in a serial and continuous manner.

While the pine trees may be dried in at least 24 hours with the wood drying kiln mentioned in the prior art document no. RU2057404, said period is shortened down to 20 hours owing to the improvements provided in our kiln according to the invention. While at least 350-400 kWh of energy is consumed in order to dry 1 meter cube of wood with the kilns according to the prior art, said amount is reduced down to 170 kwh with our drying kiln that includes the improvements according to the invention being the subject matter of the application.

The descriptions related to the figures that assist in a better understanding of the wood drying kiln according to the invention are provided below:

Figure-1: The front perspective view of the drying kiln according to the application along with the wood to be dried Figure-2: A detailed top view of the kiln according to the invention being the subject matter of the application in a state in which the door thereof is closed

Figure-3: A detailed interior view of the middle section of the kiln according to the invention being the subject matter of the application

Figure-4: A detailed view of the antennas present inside the kiln according to the application

Figure-5: A detailed view of the antennas of the kiln according to the application Figure-6: A detailed view of the aeration pipe present in the drying kiln

Figure-7: A detailed view of the condensation pipe present in the drying kiln

Figure-8: A detailed view of the main diffuser antenna with the shape of inverted T

Figure-9: A detailed view of the antenna piece along with the wave transmitters Figure-10: A view of the part of the antenna piece bearing the windows

Brief descriptions of the part numbers included in the figures:

I- Wood to enter the drying kiln

2- Conveyor

3- 1st air blower

4- 2nd air blower

5- Microwave source

6- Cooling unit

7- Transformer

8- Control panel

9- Conveyor rail

10- Conveyor tray

II- Main diffuser antenna with inverted T shape

12- Corner connection antenna

13- Diffuser antenna

14- Wave transmitters

15- Window 16- Vacuum (air discharge) pipe

17- Air suction holes

18- Condensation pipe (copper pipe)

19- Water draining channel

20- Chamber

21- Chamber door

22- Leakproof derlin

23- Microwave drying unit

In our kiln according to the application, which is capable of performing a faster drying than the prior art drying kilns by applying the electromagnetic wave energy on the wood to be dried, the wood to be dried (1) is transferred within the chamber (20) by means of a conveyor (2) on which the wood to be dried (1) is placed prior to drying process and there is present a conveyor tray (10) on which the wood to be dried (1) remains throughout the drying process. Said conveyor tray (10) may move towards the interior of the chamber (20) by means of a conveyor rail (9). The tray (10) on which the wood to be dried (1) is placed and the rail mechanism (9) on which the wood is transferred within the chamber comprise the principal parts of the conveyor (2). Our kiln according to the application is fed by means of a transformer (7), and there is also present a cooling unit (6) that performs the cooling process. Our kiln according to the application comprises a microwave source (5) that generates the microwave to be applied on the wood to be dried (1), and also two blowers (3, 4). The kiln according to the application comprises the 1st air blower (3) that cools the electromagnetic generator and the 2nd air blower (4) that draws out the air inside the machine, thus forming a vacuum effect.

The chamber (20) into which the wood to be dried is placed has a cylindrical structure. Once the wood to be dried (1) is placed at the center of the chamber (20), its door (21) is closed. After the chamber door (21) has been closed, the electromagnetic waves emitted from the microwave source (5) reach at the central main diffuser antenna (11) having a structure with the shape of an inverted T, and from said main diffuser antenna, they reach, via the corner connection antenna (12), at the diffuser antennas (13) on which the windows (15) are located, and from said diffuser antennas, they are directed towards the wood to be dried (1). There is present the leakproof derlin (22), which is placed at the joints of the inverted T shaped central main diffuser antenna and thus prevents the entry of air into the antenna. In our kiln according to the application, there are present the antennas (13), which are manufactured by way of joining certain pieces and which diffuse the electromagnetic waves. Said antennas (13) are extended from the front part of the chamber (2) towards the rear part. The wood to be dried (1) is located at the center of these diffuser antennas (13). Moreover, during the opening of the windows (15) on the diffuser antennas (13), the emergence ratios of the electromagnetic waves from all the windows (15) are taken into account and the most ideal window (15) dimensions are used, in order to provide an effective reflection of the electromagnetic waves.

In our wood drying kiln according to the application, the electromagnetic wave transmitters (14) with conductive feature, which are made of aluminum and are resistant to electromagnetic waves, are mounted at the sections where the antennas (13) manufactured by way of joining certain pieces face each other. Said wave transmitters (14) both prevent the leakage of the electromagnetic waves and enable the waves to emerge in a smoother manner from the windows (15) and to be directed towards the wood to be dried (1).

In our wood drying kiln according to the application, there is present a single main diffuser antenna (11). The presence of a single main diffuser antenna (11) minimizes the leakage problem, and also, because all the waves arrive at the antennas (13) from said single main diffuser (11), the wood to be dried (1) is enabled to dry within a shorter period of time.

The single main diffuser antenna (11) employed in our wood drying kiln according to the application has a structure with the shape of an inverted T. The inverted T form of the main diffuser antenna (11) enables all the waves coming from the electromagnetic generator to be collected in a single piece. Said collection in a single piece enables a possible leakage to take place at a single location, thus reducing the leakage.

In the main diffuser antenna (11) of our kiln according to the application, a total of 4 right and left side diffuser antennas (13) are located, via the corner connection antenna (12), on the horizontal plane inside the machine. The reduction in the number of antennas enables the waves to move together in a more intense manner.

In our invention being the subject matter of the application, for the purpose of providing the air-free ambience required for the drying machine, there are present the aeration pipes (16), which extend into the chamber (20) and suck the air through the plurality of the holes (17) they carry to collect said air and move it outside. Owing to said perforated aeration pipes (16), the air inside the chamber (20) may be sucked at many points inside the chamber (20) in the zones through which the aeration pipes (16) pass within said chamber (20), thus the interior of the chamber (20) is brought into an air-free state in the desired manner.

In our kiln according to the invention, the condensation pipes (copper) (18) are added, which collect the water droplets formed on the chamber ceiling as a result of the air temperature inside the chamber of the drying kilns according to the prior art rising up to 100 degrees. These condensation pipes (copper) (18) enable the condensate to be absorbed faster, condensing and taking up the same, and they expel the water vapor taken up from the interior of the chamber (20). Owing to said improvement, the problem with the water droplets dripping on the dried wood during or at the end of the drying process is eliminated and the condensation pipes are connected with the water channel (19) at the bottom of the chamber.

In addition, all the processes of our kiln according to the invention are based upon the automation. Because all the equipment related with the kiln are connected to the automation feature by means of the control panel (8), all the operating principles may be monitored by means of automation, and it becomes possible to take immediate action in case of any failure or in any unusual case likely to be encountered during the drying process.

In our invention being the subject matter of the application, a water channel (19) is opened on the bottom of the chamber, in order to drain the water emerging from the wood during the drying process and being collected from the condensation pipes (copper) (18) during the operation.

In our kiln according to the invention, first the wood (1) is arranged in an orderly manner on the carrier tray (10), which is among the kiln equipment, according to the size, width and length. The tray (10), on which the wood is placed and which has the rail mechanism under it, is positioned by way of being pushed into the chamber (20) over the rails (9). After the chamber door (21) is completely closed, the kiln is operated. During the operation, the highest frequency (microwave) generator starts running based on the automation and it directs the electromagnetic waves towards the transmitter antennas (13) under the influence of the power supply. The electromagnetic waves infiltrating outside through the antenna windows (15) are enabled to infiltrate the wood (1) being dried, which has a high moisture content, the heat of the water within the wood is increased and it enables the water molecules to start moving. Water molecules move towards the surface section of the wood. The water molecules, which are influenced by the electromagnetic waves, heat up the air inside the chamber (20) up to a temperature of 100 degrees. The emerging water evaporates and softens the surface of the wood, and also enables the water to move from the interior of the wood to the outside thereof in a faster manner.

The drying periods differ according to the tree species, with drying being achieved within a period of time that is 10 times shorter than the classical drying kilns. For example, the pine tree can be dried within minimum 48 hours with classical drying processes, whereas it is possible to dry the same in 20 hours with our kiln according to the application.