JP2013173269A - Method of drying honeycomb structural body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of drying a honeycomb structural body capable of improving production efficiency by preventing the occurrence of defective products or a honeycomb structural body that needs to be redried.SOLUTION: A method of drying a honeycomb structural body includes at least: an irradiation drying process of irradiating and drying the honeycomb structural body with microwaves; a moisture content monitoring process of monitoring the moisture content of the honeycomb structural body; and a moisture content controlling microwave irradiation output control process of controlling the irradiation output of microwaves according to the moisture content of the honeycomb structural body.

Description

  The present invention relates to a method for drying a honeycomb structure in which the microwave irradiation output is controlled in accordance with the moisture content of the honeycomb structure.

Honeycomb compacts are widely used for industrial applications such as electrical appliances and automobile exhaust gas. When manufacturing such a honeycomb formed body, first, ceramics is used as a main raw material, water and additives are kneaded to form a uniform clay, and then a honeycomb-shaped structure (hereinafter, referred to as extrusion structure) is formed. In some cases, the honeycomb structure is dried and fired.
The honeycomb structure after extrusion has a moisture content of about 30 to 40% by mass, and if the firing process is performed as it is, cracks and cracks are generated in the honeycomb structure. In order to prevent this, a drying step is required to reduce the moisture content of the honeycomb structure to about 10% by mass in advance.

  As a method for drying the honeycomb structure, a natural drying method in which the honeycomb structure is allowed to stand at room temperature, a humidity control drying method in which the humidity of the drying environment is adjusted and drying is performed, or the honeycomb structure is irradiated with microwaves for drying. The microwave drying method to perform etc. are mentioned.

  According to the natural drying method, since the water content is originally intended to be low, moisture is gently evaporated from the honeycomb structure, so there are few occurrences of cracks and cracks, and yield is a problem. Absent. However, a honeycomb having a high water content used for an industrial catalyst or the like has a problem that when the drying proceeds from the surface, cracks or cracks are likely to occur on the honeycomb surface due to shrinkage of the surface or the like. For honeycombs that can be naturally dried, the drying time until the amount of moisture that can be fired is not only affected by the weather, but it takes too long to dry even in good weather. There is a problem that efficiency does not increase.

On the other hand, in the humidity control drying method, the drying time can be shortened compared with the natural drying method by adjusting the humidity of the drying environment of the honeycomb structure without being influenced by the weather.
However, with this drying method, the yield is originally about 50% to about 80%. If the humidity control is mistaken, drying unevenness may occur, and cracks and cracks that affect the yield may occur. In order to prevent the occurrence of such defective products, it is necessary to increase the temperature from room temperature to around 80 ° C. over about 10 days and maintain the humidity high. As a result, it is necessary to secure a drying time of around 10 days. Therefore, it can be said that the drying time is still long from the viewpoint of production efficiency.
Moreover, it is difficult for the humidity control drying method to take a continuous drying method by placing a honeycomb structure on a belt conveyor or the like, and a batch drying method is used. In the case of the batch type, for example, a process such as installing a honeycomb structure in a drying furnace under a humidity control environment or taking out the honeycomb structure after drying is required, which further reduces the production efficiency. Become.

  On the other hand, as a microwave drying method, a batch-type drying method in which a honeycomb structure is installed in a drying furnace having a uniform electrolytic distribution, or a continuous drying by passing the honeycomb structure continuously into the drying furnace. The drying method by a formula is known (for example, cited documents 1, 2 etc.). According to the microwave drying method, the drying time can be significantly reduced as compared with the natural drying method and the humidity control drying method, and the production efficiency can be improved.

However, in the conventional microwave drying method, the moisture content of the honeycomb structure cannot be continuously monitored during drying, and after drying for a predetermined time, the honeycomb structure is extracted as a sample, and the moisture content is determined based on the weight change. Was used as a measure for the completion of drying. In such a method, it is difficult to measure the moisture content of all of the honeycomb structures during drying, and thus it is not only possible to prevent variation in individual drying conditions, It was not possible to confirm the drying condition.
Therefore, there are many cases where whitening, cracks and cracks are observed, those that become defective due to shrinkage and deformation, and those that need to be dried again due to insufficient drying. Therefore, it was difficult to dry the honeycomb structure with a high yield.

JP 2006-88685 A JP 2003-100441 A

  An object of the present invention is to provide a method for drying a honeycomb structure capable of improving production efficiency by preventing generation of defective products and honeycomb structures that need to be re-dried.

In order to solve the above problem, the present inventor has reviewed the process of irradiating the honeycomb structure with microwaves.
In such a case, when microwaves are further irradiated to the part where the honeycomb structure has been excessively dried, the temperature of the part may rise abnormally due to overheating, which may cause whitening, cracking, or cracking. It turns out that it leads to outbreak. Further, it was found that even when partial overburning was not observed, the honeycomb structure contracted or deformed when the entire honeycomb structure was excessively dried.
The present inventor has intensively studied to prevent whitening, cracking, cracking, and the like of the honeycomb structure based on the cause of occurrence of problems such as whitening as described above. As a result, if the moisture content of the honeycomb structure is monitored and the microwave output is controlled in accordance with the moisture content, the drying condition of the honeycomb structure can be individually controlled, resulting in excessive drying or poor drying. It has become possible to prevent the occurrence of whitening and the like. By this method, it was found that the yield of the drying process was increased and the production efficiency was improved, and the present invention was completed.

  That is, the first embodiment according to the present invention is a method for drying a honeycomb structure, an irradiation drying step of irradiating the honeycomb structure with microwaves and drying, and moisture for monitoring the moisture content of the honeycomb structure A method for drying a honeycomb structure, comprising: an amount monitoring step; and a moisture amount control microwave irradiation output control step for controlling a microwave irradiation output in accordance with a moisture amount of the honeycomb structure. .

  According to the method for drying a honeycomb structure of the present invention, it is possible to prevent generation of defective products and honeycomb structures that need to be re-dried, and it is possible to improve production efficiency by increasing yield. .

It is a flowchart which shows one Embodiment of the moisture content monitoring process in the drying method of the honeycomb structure of this invention, and the microwave irradiation output control process for moisture content control. It is a flowchart which shows one Embodiment of the temperature monitoring process in the drying method of the honeycomb structure of this invention, and the microwave irradiation output control process for temperature control. It is a mimetic diagram showing one mode of a continuous drying device which dries a honeycomb structure continuously. It is a perspective view showing one mode of a polygonal columnar honeycomb structure coated with a covering material. [Fig. 5] Fig. 5 is a perspective view showing an example of a polygonal columnar honeycomb structure coated with a coating material having a mode different from that of Fig. 4. FIG. 5 is a perspective view in which a polygonal columnar honeycomb structure different from that in FIG. 4 is coated with a coating material. It is a perspective view which shows one aspect | mode of the cylindrical honeycomb structure which coat | covered the coating material. FIG. 8 is a perspective view in which a cylindrical honeycomb structure having a mode different from that in FIG. 7 is coated with a coating material. It is the figure which showed the reduction | decrease result of the moisture content by progress of the drying time in the drying process of Example 1. FIG.

Hereinafter, the general form of the method for drying a honeycomb structure according to the present invention will be described in detail.
First, the drying method of the present invention targets a honeycomb structure. The honeycomb structure is not a constant shape, and examples thereof include a polygonal columnar shape having a honeycomb surface having a polygonal shape such as a quadrangle, a pentagon, and a hexagon, and a columnar shape having a circular honeycomb surface.
The drying method of the present invention includes an irradiation drying process for irradiating such honeycomb structure with microwaves, a moisture amount monitoring process for monitoring the moisture content of the honeycomb structure, and a moisture content of the honeycomb structure. At least a moisture amount control microwave irradiation output control step for controlling the microwave irradiation output according to the above. Each process may be performed in order and may be performed simultaneously.
When each step is performed simultaneously, the moisture content is monitored while irradiating the honeycomb structure with microwaves, and the microwave irradiation output is controlled according to the moisture content.
Moreover, the microwave is a general term for radio waves having a frequency of 300 MHz to 30 GHz (wavelength 1 cm to 1 m), and a microwave with a frequency in this range can be used as the microwave irradiated to the honeycomb structure. In general, a microwave having a frequency of around 2450 MHz is used, and the wavelength (λ) of the microwave in this case is about 120 mm.

In the method for drying a honeycomb structure of the present invention, the microwave irradiation output control step for controlling the moisture content is performed so that the moisture reduction amount of the honeycomb structure is 0.2 to 1.0 mass% / min. The step of controlling the output is preferable. If the amount of moisture reduction is within this range, the honeycomb structure does not dry rapidly, and partial overburning can be easily prevented. Therefore, it becomes easy to quickly dry while preventing whitening, cracking, and cracking of the honeycomb structure. When the amount of moisture reduction exceeds 1.0% by mass / min, it may be partially burnt due to rapid drying, leading to a decrease in yield due to whitening or the like. If the water loss is less than 0.2% by mass / min, drying is slow, which is not appropriate.
The honeycomb structure after extrusion has a moisture content of about 30 to 40% by mass, and when dried to about 10% by the drying method of the present invention, the moisture reduction amount is 0.5% by mass / min. Further, if the microwave irradiation output is controlled, drying can be completed in about 1 hour, and it is possible to quickly move to a subsequent process such as firing, which is further preferable.

In the method for drying a honeycomb structure of the present invention, the moisture amount monitoring step may include a step of measuring the moisture amount by irradiating the honeycomb structure with a microwave for moisture amount measurement. If it is the measuring method which irradiates with a microwave, it will be possible to measure the water content of each of the dried honeycomb structures without destroying the honeycomb structures. Therefore, by controlling the microwave irradiation output in accordance with the moisture content of each honeycomb structure obtained from the measurement result, a yield above a certain level can be ensured.
As a method for measuring the amount of moisture by microwave irradiation, a microwave oscillator is used to irradiate the honeycomb structure with the microwave, and the microwave reflected from the honeycomb structure or the microwave transmitted through the honeycomb structure is measured. The method of doing is mentioned. In this case, if the frequency of the microwave is set to a frequency band different from that of the drying microwave, the microwave does not interfere with the drying microwave. Moreover, the microwave for drying is not inhibited.
If the moisture content of the honeycomb structure is up to about 20%, monitoring may be performed based on either the microwave reflected from the honeycomb structure or the transmitted microwave. If the moisture content is less than 20%, By measuring both reflected and transmitted microwaves, the water content can be monitored more precisely.
Moreover, it is preferable to irradiate the honeycomb side surface with the microwave for measuring the moisture content. If the honeycomb surface is irradiated, not only the moisture content of the honeycomb structure but also the moisture content in the air inside the honeycomb is measured, so that more accurate measurement cannot be performed. If the honeycomb side surface is irradiated with microwaves, the moisture content in the air inside the honeycomb is not measured, so the moisture content in the honeycomb structure can be measured more accurately.

In the method for drying a honeycomb structure according to the present invention, the moisture amount monitoring step can include a step of calculating the moisture amount by measuring the mass of the honeycomb structure. If the mass of the honeycomb structure being dried is measured over time, the amount of individual moisture can be measured from the mass difference without destroying the honeycomb structure. Therefore, by controlling the microwave irradiation output according to the water content of each honeycomb structure obtained from the measurement result, a yield above a certain level can be secured.
Examples of the method for measuring the mass of the honeycomb structure include a method in which individual honeycomb structures are mounted directly or indirectly (for example, every drying equipment) on a mass meter and an irradiation drying process is performed.
Moreover, the mass measurement of the honeycomb structure can be performed in combination with the moisture content measurement step using the microwave. By using together, the moisture content of the honeycomb structure can be monitored more strictly.

In the method for drying a honeycomb structure of the present invention, in addition to a process for monitoring the moisture content of the honeycomb structure, a temperature monitoring process for monitoring the temperature of the honeycomb structure, and microwave irradiation according to the temperature of the honeycomb structure And a temperature control microwave irradiation output control step for controlling the output. If the temperature is monitored in addition to monitoring the amount of moisture, abnormal temperature rise of the part due to local drying or overburning can be confirmed, so the microwave irradiation output is controlled according to the temperature rise Thus, whitening, cracking, and cracking of the honeycomb structure can be prevented in advance.
As a method for monitoring the temperature of the honeycomb structure, for example, a method of measuring and monitoring the temperature of the surface of the honeycomb structure with a non-contact type radiation thermometer, or a temperature measurement treatment such as a thermocouple on the surface or inside of the honeycomb structure. Examples include a method of installing a tool and measuring and monitoring the temperature of the surface and the inside.

The temperature control microwave irradiation output control step is preferably a step of controlling the microwave irradiation output so that the temperature of the honeycomb structure becomes 80 ° C. to 100 ° C. If it is within this temperature range, abnormal drying of the part due to local drying or overburning does not occur, so the honeycomb structure is dried under stable conditions without whitening, cracking or cracking. be able to.
If the temperature exceeds 100 ° C, it indicates that a temperature increase due to local drying or over-burning has occurred. Therefore, in order to prevent whitening and the like, the microwave irradiation output is decreased to lower the temperature to 100 ° C or less. Is desirable. When the temperature reaches 110 ° C., it is desirable to stop the microwave output in order to prevent the honeycomb structure from becoming defective due to whitening or the like.
Further, when the temperature is lower than 80 ° C., drying is slow and is not appropriate. Therefore, it is desirable to increase the microwave irradiation output so that the temperature is 80 ° C. or higher.

In the method for drying a honeycomb structure of the present invention, the irradiation drying step can include a step of drying the honeycomb structure by irradiating the honeycomb structure with a batch type drying apparatus. In this case, the batch-type drying apparatus includes at least a microwave irradiation tank, and the microwave irradiation tank includes at least one microwave irradiation apparatus that irradiates microwaves.
In addition, if the microwave irradiation tank includes a rotating body on which the honeycomb structure is mounted and is driven to rotate, the honeycomb structure can be rotated, so that the microwave can be irradiated uniformly. Thus, local drying and overburning of the honeycomb structure due to uneven irradiation can be prevented.
Further, when the microwave irradiation tank is not provided with a rotating body, the microwave irradiation tank is uniformly irradiated with microwaves by setting the volume of the microwave irradiation tank to about 50 times or more the volume of the honeycomb structure. It is possible to prevent local drying and overburning.

In the method for drying a honeycomb structure of the present invention, the irradiation drying step can include a step of irradiating the honeycomb structure with microwaves using a continuous drying apparatus. In this case, the continuous drying apparatus includes a microwave irradiation tank provided with a microwave generation apparatus that generates microwaves and irradiates the honeycomb structure to dry, and electromagnetic waves installed before and after (entrance / exit) of the microwave irradiation tank. A microwave irradiation tank comprising at least an irradiation tank inlet and an irradiation tank outlet provided with a shutter, and a transfer device for carrying the honeycomb structure and sequentially transporting the irradiation tank inlet, the microwave irradiation tank, and the irradiation tank outlet. This is an apparatus for irradiating the honeycomb structure passing through the inside with microwaves.
With such a drying device, the honeycomb structure is sequentially placed on the transfer device, so that the honeycomb structure is transferred from the irradiation tank inlet to the microwave irradiation tank and dried, and then dried to the irradiation tank outlet. By taking out the honeycomb structure, a continuous drying process can be performed. In this drying apparatus, since the microwave irradiation time can be adjusted also by adjusting the conveyance speed of the conveyance apparatus, the drying of the honeycomb structure can be controlled.

The microwave irradiation tank of the continuous drying apparatus includes a plurality of microwave generators installed in parallel with the conveyance direction of the honeycomb structure, and in the irradiation drying process, the plurality of microwave generators are conveyed by the conveyance apparatus. A step of sequentially drying the honeycomb structure, and a microwave irradiation output control step for moisture content control includes a microwave generator for drying the honeycomb structure and / or a next drying according to the moisture content of the honeycomb structure. The step of controlling the microwave irradiation output of the microwave generator to be performed can be included.
By providing the microwave irradiation tank with a plurality of microwave generators, a larger number of honeycomb structures can be sequentially processed sequentially than in the case of a single microwave generator. In this case, the honeycomb structure is controlled by controlling the microwave irradiation output of the microwave generator that is drying the honeycomb structure and / or the microwave generator that is next dried according to the moisture content of the honeycomb structure. It becomes possible to appropriately adjust the irradiation output of the microwave irradiated to the body. As a result, it is possible to flexibly cope with variations in individual moisture contents of the honeycomb structure.
Here, the microwave irradiation output can be arbitrarily controlled. For example, when controlling only the microwave generator that is drying the honeycomb structure, controlling only the microwave generator that is dried next, and controlling both the microwave generator that is being dried and then dried There are cases.

In the present invention, when a continuous drying apparatus is used, the temperature control microwave irradiation output control step includes a microwave generator for drying the honeycomb structure and / or a microwave for drying the honeycomb structure in accordance with the temperature of the honeycomb structure. The step of controlling the microwave irradiation output of the generator can be included. Thereby, it becomes possible to appropriately adjust the irradiation output of the microwave irradiated to the honeycomb structure, and it is possible to flexibly cope with variations in individual temperatures of the honeycomb structure such as a local temperature rise.
Similarly to the above, the microwave irradiation output can be arbitrarily controlled. For example, when controlling only the microwave generator that is drying the honeycomb structure, controlling only the microwave generator that is dried next, and controlling both the microwave generator that is being dried and then dried There are cases.

In the method for drying a honeycomb structure of the present invention, the honeycomb structure is a polygonal columnar honeycomb structure having a polygonal honeycomb surface, and at least a corner portion of the surface of the honeycomb structure before the irradiation drying step. And each side can include a coating step of coating a coating material that protects the honeycomb structure from microwaves.
In the polygonal honeycomb structure, at least one of the diagonal lines of the honeycomb surface, the length of the side of the polygon, or the height of the honeycomb structure has a wavelength of 0. When it is 5 times or more, the covering material can be coated in order to prevent the occurrence of whitening, cracks, cracks and the like in advance. The diagonal line is a line segment excluding the side among the line segments connecting two different vertices on the polygon, and all polygons other than the triangle have two or more diagonal lines.
In the coating step, a coating material is coated on at least the corners and each side of the surface of the honeycomb structure. Since microwaves are likely to be concentrated at corners and sides, if these parts are covered, the occurrence of whitening, cracks, cracks, etc. of the parts can be prevented.
When coating with a coating material, the coating interval is preferably 0.5 to 2 times the wavelength of the microwave. In the honeycomb structure, at least one of the diagonal lines of the honeycomb surface, the length of the side of the polygon, or the height of the honeycomb structure is 0.5 times or more of the wavelength of the microwave. In some cases, cracks, cracks and the like are likely to occur on the honeycomb surface and side surfaces having a width of 0.5 times or more, and these can be prevented. For example, when the height of the honeycomb structure is 0.5 to 2 times the wavelength of the microwave, whitening is achieved by coating the corners and each side of the honeycomb side surface with a coating material. Cracks and cracks can be prevented. Further, when the height of the honeycomb structure is at least twice as long as the wavelength of the microwave, the honeycomb side surface is cracked only by covering the corner and each side of the honeycomb side surface with a coating material. Since cracks or the like may occur, it is preferable to cover the honeycomb side surface at a distance of 0.5 to 2 times the wavelength of the microwave from each side in addition to the corners and each side. .

In the method for drying a honeycomb structure according to the present invention, the honeycomb structure is a columnar honeycomb structure having a circular honeycomb surface, and at least at the end of the column on the surface of the honeycomb structure before the irradiation drying step. A coating step of coating a coating material that protects the honeycomb structure from microwaves can be included.
In the cylindrical honeycomb structure, when either the diameter of the circular honeycomb surface or the height of the honeycomb structure is 0.5 times or more of the wavelength of the microwave, whitening or cracking, In order to prevent the occurrence of cracks or the like in advance, the covering material can be coated.
In the coating step, a coating material is coated on at least the cylindrical end portion of the surface of the honeycomb structure. The cylindrical end portion is a portion where the honeycomb surface and the honeycomb side surface are in contact with each other, and is a portion where the microwave tends to concentrate. If this cylindrical end portion is covered, the occurrence of whitening, cracking, cracking, etc. of the portion can be prevented.
When coating with a coating material, the coating interval is preferably 0.5 to 2 times the wavelength of the microwave. In the honeycomb structure, when either the diameter of the honeycomb surface or the height of the honeycomb structure is 0.5 times or more of the wavelength of the microwave, the width or the like is 0.5 times or more. This is because cracks, cracks and the like are likely to occur on a certain honeycomb surface or side surface, and these can be prevented. For example, when the diameter of the honeycomb surface is 0.5 to 2 times the wavelength of the microwave, the cylindrical end of the honeycomb structure is covered with a coating material, thereby whitening, cracks, cracks, etc. Can be prevented. In addition, when the honeycomb surface has a diameter that is twice or more the wavelength of the microwave, cracking, cracking, or the like generated on the honeycomb surface can be achieved only by covering the cylindrical end of the honeycomb structure with a coating material. In view of the possibility of occurrence, it is preferable to cover the honeycomb surface and the honeycomb side surface at a distance of 0.5 to 2 times the wavelength of the microwave from the column end in addition to the column end. In other words, in this case, the honeycomb material is coated on the honeycomb side surface so that the honeycomb surface is coated with a solar cruciform and the honeycomb surface on the upper part of the honeycomb structure is connected to the cruciform coating material coated on the lower honeycomb surface. The material will be coated.

  In this invention, it is preferable that the coating width | variety at the time of coat | covering with a coating material is 0.5 times or less of the wavelength of a microwave. This is because if the coating width exceeds 0.5 times, the microwave may excessively hinder the penetration of the honeycomb structure, resulting in a drying delay. If the coating width is 0.1 times or more of the wavelength of the microwave, the honeycomb structure can be sufficiently protected from the microwave. By setting the reference of the coating width to 0.2 times the wavelength of the microwave and appropriately adjusting the coating width according to the shape and size of the honeycomb structure, the honeycomb structure can be efficiently dried.

  When the covering material includes a microwave reflecting material, the microwave reflecting material is preferably a metal material having electrical conductivity. If it is a metallic material having electrical conductivity, it is possible to effectively reflect the microwave and sufficiently protect the honeycomb structure from the microwave. Examples of the conductive metal material include materials made of any of aluminum, copper, iron, stainless steel, brass, or a combination thereof.

  Next, an embodiment of the method for drying a honeycomb structure of the present invention will be described more specifically with reference to the drawings. In this case, the present invention is not limited to the embodiment with reference to the drawings.

FIG. 1 is a flowchart showing one embodiment of a moisture amount monitoring step and a moisture amount control microwave irradiation output control step in the honeycomb structure drying method of the present invention.
As shown in FIG. 1, the moisture content of the honeycomb structure is measured by measuring the moisture content. If the moisture content is larger than the planned value, the microwave irradiation output is increased to reduce the moisture content, and then Measure moisture content. When the moisture content is smaller than the planned value, the microwave irradiation output is decreased to relax the drying conditions, and then the moisture content is measured. If the amount of moisture is within the range of the planned value, the amount of moisture is then measured while maintaining the microwave irradiation output amount.
As described above, the moisture amount measurement and the control of the microwave irradiation output are repeatedly performed. When the moisture amount of the honeycomb structure becomes 10% or less, the microwave irradiation is stopped and the drying is finished.
The measurement of the moisture content is continuously performed from the start to the end of the drying of the honeycomb structure, and can be continuously performed or intermittently at predetermined intervals.
In addition, the plan value of moisture content can be determined arbitrarily. For example, when a honeycomb structure having a moisture content of 40% by mass is dried at a moisture reduction amount of 0.5% by mass / min until the moisture content reaches 10% by mass, after 20 minutes from the start of the drying process, After the minute, the planned values at the end of drying are 40% by mass, 30% by mass, 20% by mass and 10% by mass, respectively.

Here, in the case of a batch-type drying apparatus having only one microwave generator or a continuous dryer, the microwave irradiation output is controlled by the microwave generator that is irradiating the honeycomb structure with microwaves. Against.
On the other hand, when it is a continuous drying apparatus and includes a plurality of microwave generators, the irradiation output can be arbitrarily controlled. Control is performed only on the microwave generator that is irradiating the honeycomb structure with microwaves, only on the microwave generator that is irradiated next, and generation of microwaves that are irradiated and irradiated next The case where it carries out with respect to both of apparatuses is mentioned.

FIG. 2 is a flow diagram showing an embodiment of a temperature monitoring step and a temperature control microwave irradiation output control step in the honeycomb structure drying method of the present invention.
As shown in FIG. 2, the temperature of the honeycomb structure is measured by temperature measurement. If the temperature is higher than the planned value, the microwave irradiation output is reduced to lower the temperature, and then the temperature is measured. . If the temperature is lower than the planned value, the microwave irradiation output is increased to increase the temperature, and then the temperature is measured. If the temperature is within the range of the planned value, the temperature is then measured while maintaining the microwave irradiation output amount.
Thus, the temperature measurement and the control of the microwave irradiation output are repeated, and when the temperature of the honeycomb structure greatly exceeds the planned value, the microwave irradiation is stopped and the drying is interrupted.
The measurement of temperature is continuously performed from the start to the end of drying of the honeycomb structure, and can be performed continuously or intermittently at predetermined intervals.
In addition, the plan value of temperature can be determined arbitrarily. For example, when the temperature during drying is within a range of 80 ° C. to 100 ° C. as a planned value, microwave irradiation can be set to stop when the temperature exceeds 110 ° C. In this case, the irradiation output amount is maintained when the temperature is in the range of 80 ° C. to 100 ° C., the irradiation output is decreased when the temperature exceeds 100 ° C., and the irradiation output is increased when the temperature is lower than 80 ° C.

Here, in the case of a batch-type drying apparatus having only one microwave generator or a continuous dryer, the microwave irradiation output is controlled by the microwave generator that is irradiating the honeycomb structure with microwaves. Against.
On the other hand, when it is a continuous drying apparatus and includes a plurality of microwave generators, the irradiation output can be arbitrarily controlled. Control is performed only on the microwave generator that is irradiating the honeycomb structure with microwaves, only on the microwave generator that is irradiated next, and generation of microwaves that are irradiated and irradiated next The case where it carries out with respect to both of apparatuses is mentioned.

When using both moisture measurement and temperature measurement, if the moisture content is higher than the planned value and the temperature is higher than the planned value, the microwave irradiation output will be increased from the moisture measurement, From the temperature measurement, the irradiation output is reduced. In this case, the temperature measurement result can be prioritized and the irradiation output can be reduced. This is because although the drying time slightly increases due to a decrease in irradiation output, it is possible to avoid a decrease in yield due to whitening caused by a temperature rise.
If the moisture content is lower than the planned value and the temperature is lower than the planned value, the microwave irradiation output will be decreased from the moisture measurement, but the irradiation output will be increased from the temperature measurement. Become. In this case, the temperature measurement result can be prioritized and the irradiation output can be increased. This is because if the temperature does not exceed the planned value, the yield does not decrease, and the drying time can be shortened by increasing the irradiation output.
As described above, when there is a contradiction in the policy of microwave irradiation output control derived from both measurements, the microwave irradiation output is appropriately controlled in consideration of the yield and drying time of the honeycomb structure. be able to.

  Examples of the drying method of the present invention include a batch method in which a honeycomb structure is installed in a drying chamber having a microwave irradiation function, and a continuous drying method using a continuous drying apparatus. An example of the continuous drying apparatus used in the drying method of the present invention will be described with reference to FIG.

The continuous drying apparatus 1 that can be used in the drying method of the present invention is basically based on a microwave irradiation tank 2 made of a metal casing that multi-reflects microwaves, and the microwave generators 3a to 3d and the honeycomb structure are contained therein. There are provided moisture measuring microwave oscillators 5a to 5d for measuring the moisture content of the bodies 4a to 4d, and a radiation thermometer 6 for measuring the temperature of the honeycomb structures 4a to 4d. Moreover, the irradiation tank inlet 7 and the irradiation tank outlet 8 are provided with the electromagnetic wave shutter 9 for preventing that a microwave is discharge | released outside.
The honeycomb structure 4 is fed into the irradiation tank from the irradiation tank inlet 7 by the conveyor 10, and is sent out of the irradiation tank after the microwave irradiation. Further, warm air 11 is fed into the irradiation tank from below the conveyor 10 and warm air is discharged from the exhaust port 12 in order to promote drying of the honeycomb structure.

The moisture contents of the honeycomb structures 4a to 4d are respectively measured by the moisture measuring microwave oscillators 5a to 5d, and the irradiation outputs of the microwave generators 3a to 3d are controlled according to the moisture contents. The temperature of the honeycomb structure is measured by the radiation thermometer 6, and the irradiation outputs of the microwave generators 3a to 3d are controlled according to the temperature.
The microwave generators 3a to 3d can individually control the irradiation output. For example, the moisture content of the honeycomb structure 4a is measured by the moisture content measurement microwave oscillator 5b, and only the microwave generator 3a that is irradiating the microwave is controlled according to the moisture content, or only the 3b that is irradiated next. Or both 3a and 3b can be controlled. The control of the irradiation output of the microwave generator according to the temperature measurement result can be similarly controlled individually.

FIG. 4 is a perspective view showing an example of a polygonal columnar honeycomb structure coated with a coating material to which the present invention is applied. The honeycomb structure 13 is a quadrangular prism-shaped structure in which the honeycomb surface 14 has a quadrangular shape, and an aluminum tape 15 is coated as a covering material so as to protect the corners 16a and sides 16b of the surface of the honeycomb structure. ing.
The honeycomb structure 13 has a length of each side of the honeycomb surface and a height of the honeycomb structure that is 0.5 to 2 times the wavelength of the microwave. If the part 16a and each side 16b are protected by a covering material, whitening, cracks, cracks, and the like due to drying by irradiation with microwaves can be prevented.

  FIG. 5 is a perspective view in which an aluminum susceptor is used as a covering material for the honeycomb structure 13 similar to that in FIG. 4. The susceptor 17 covers the corner portions 18a and the sides 18b on the surface of the honeycomb structure, similarly to the aluminum tape of FIG. The upper and lower susceptors and the susceptor covering the sides are connected by an aluminum bolt 19.

FIG. 6 is a perspective view in which a rectangular pillar-shaped honeycomb structure different from the honeycomb structure of FIG. 4 is coated with an aluminum tape as a coating material. In the honeycomb structure 13, the length of each side of the honeycomb surface is 0.5 to 2 times the wavelength of the microwave, while the height of the honeycomb structure is 2.5 of the wavelength of the microwave. Is double. Therefore, in order to prevent whitening, cracks, cracks, and the like due to microwave irradiation, not only the corners and sides of the honeycomb structure 13 are protected with a covering material, but also 0.5 times the wavelength on the honeycomb side surface. It is necessary to protect with a covering material at intervals of up to twice as long. In FIG. 6, the honeycomb side surface is protected by an aluminum tape 15 so as to be divided into two equal parts, and the honeycomb side surface is coated with a coating material at intervals of 1.25 times the wavelength of the microwave. .
Here, when the width of the aluminum tape is uniformly 0.2 times the wavelength of the microwave, the honeycomb structure can be dried satisfactorily. Furthermore, only the aluminum tape in the longitudinal direction of the honeycomb structure has a width A ′ of 0.2 to 0.4 times the wavelength of the microwave, whereby the honeycomb structure is uniformly dried. In this way, the honeycomb structure can be dried more efficiently by setting the reference of the coating width to 0.2 times the wavelength of the microwave and appropriately adjusting the coating width according to the shape and size of the honeycomb structure. Can do.

FIG. 7 is a perspective view showing an example of a cylindrical honeycomb structure coated with a covering material. The honeycomb structure 13 has a circular honeycomb surface 14 and is coated with an aluminum tape 15 as a covering material so as to protect the cylindrical end portion 20 on the surface of the honeycomb structure.
The honeycomb structure 13 has a honeycomb surface diameter and a height of the honeycomb structure 0.5 to 2 times the wavelength of the microwave, and therefore covers the cylindrical end portion 20 of the honeycomb structure 13. If it protects with a material, whitening, a crack, a crack, etc. by irradiating with a microwave and drying can be prevented.

  FIG. 8 is a perspective view in which a cylindrical honeycomb structure different from the honeycomb structure of FIG. 7 is coated with an aluminum tape as a coating material. The honeycomb structure 13 has a honeycomb structure whose height is 0.5 to 2 times the wavelength of the microwave while the diameter of the honeycomb surface is 2.5 times the wavelength of the microwave. Therefore, in order to prevent whitening, cracks, cracks, and the like due to microwave irradiation, not only the cylindrical end portion of the honeycomb structure 13 is protected by the coating material, but also the honeycomb surface and the honeycomb side surface are 0.5 times the wavelength. It is necessary to protect with a covering material at intervals of up to twice as long. In FIG. 8, the honeycomb surface and the honeycomb side surface are protected by an aluminum tape 15 so as to be divided into four equal parts, and the honeycomb surface and the honeycomb side surface are covered with a coating material at intervals of 1.25 times the microwave wavelength. Will be.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

Creation of honeycomb structure [Honeycomb structure 1]
By extruding what was kneaded with talc, kaolin, alumina, binder, water, additives and the like into a uniform clay, the honeycomb surface was 50 mm long, the honeycomb surface was 50 mm wide, the height was 50 mm, A small rectangular pillar-shaped honeycomb structure 1 (water content: 30% by mass) having a wall thickness of 1 mm and 484 cells (vertical direction: 22, lateral direction: 22) was prepared.

[Honeycomb structure 2]
As in the method for producing the honeycomb structure 1, a clay-like one was extruded and formed to have a honeycomb surface of 150 mm in length, a honeycomb surface of 150 mm in width, a height of 200 mm, a wall thickness of 100 μm, and a cell number of 484 (in the longitudinal direction). : 22 pieces, lateral direction: 22 pieces) square pillar-shaped honeycomb structure 2 (water content: 30% by mass) was prepared.
The following drying treatment was performed using the prepared honeycomb structures 1 and 2.

Drying of honeycomb structure by batch method [Example 1]
The honeycomb structures 1 (20 pieces) were placed one by one in a batch-type drying apparatus, and continuously dried with microwaves until the moisture content became 10% by mass. The presence or absence of whitening, cracks and cracks was evaluated. In addition, from the viewpoint of production efficiency, the yield of the drying process was 80% or more.
As a batch type drying apparatus, a microwave irradiation apparatus and a microwave irradiation tank including a rotating body on which a honeycomb structure is mounted and rotationally driven are used.
The moisture content of the honeycomb structure 1 was reflected from the honeycomb structure 1 by irradiating the honeycomb structure 1 with a microwave having the same frequency band as the drying microwave at an output of 20 mW using a microwave oscillator. This was done by measuring microwaves. Based on the result of the moisture content measurement, the microwave irradiation output was controlled so that the moisture reduction amount was 0.33 mass% / minute so that the drying could be completed in 1 hour.
The water content was determined to be a value that decreases with a decrease of 0.33 mass% / min. That is, the planned values at the start of the drying process, 30 minutes later, and at the end of the drying are 30% by mass, 20% by mass, and 10% by mass, respectively. When the moisture content of the honeycomb structure 1 was larger than the planned value, the irradiation output was increased, and when it was lower than the planned value, the irradiation output was decreased. When the water content was the planned value, the irradiation output amount was maintained, and when the water content became 10% by mass or less, the drying was finished.
The microwave irradiation output was controlled by turning on / off the power of the microwave irradiation apparatus.
The specifications of the microwave irradiation device are: output per honeycomb structure: 1 kW (variable continuously), frequency: 2450 ± 30 MHz, power input: three-phase AC, 200 V, and the specifications of the microwave irradiation tank are internal dimensions: 600 W × 700 H × 1200 L (mm), inner furnace material: SUS304. The results are shown in Table 1.

[Example 2]
In the same manner as in Example 1, the honeycomb structure 1 was placed in a batch-type drying apparatus and dried until the water content became 10% by mass. The moisture content was measured in the same manner as in Example 1, and the microwave irradiation output was controlled so that the amount of moisture reduction was 0.33 mass% / minute (planned value) so that drying was completed in 1 hour.
Further, the temperature of the surface of the honeycomb structure 1 being dried was measured using a non-contact type radiation thermometer, and the microwave irradiation output was controlled based on the result of the temperature measurement. The temperature is a planned value that the surface of the honeycomb structure 1 is in the range of 80 ° C. to 100 ° C., and even if it is partly less than 80 ° C., the irradiation output is increased and partly exceeds 100 ° C. In some cases, the irradiation power was reduced. When the temperature was the planned value, the irradiation output amount was maintained, and when at least 110 ° C. or higher, the drying was interrupted.
In addition, when the part less than 80 degreeC and the part exceeding 100 degreeC coexisted in the honeycomb structure 1, irradiation output was reduced from a viewpoint which prevents whitening etc. from generating over the part over 100 degreeC.
In addition, when the water content was higher than the planned value and the temperature was higher than the planned value, the irradiation output was decreased in order to prevent whitening and the like from occurring. On the other hand, when the amount of water was less than the planned value and the temperature was lower than the planned value, the irradiation output was increased in order to shorten the drying time.

[Example 3]
In order to protect the corners and each side of the honeycomb structure 2, an aluminum tape having a thickness of 0.1 mm and a width A (FIG. 4) was coated as a covering material (FIG. 4). After that, in the same manner as in Example 1, the honeycomb structure 2 was placed in a batch-type drying apparatus and dried until the water content became 10% by mass.

[Comparative Example 1]
The honeycomb structure 1 was installed in the same batch-type drying apparatus as in Example 1, and dried until the water content became 10% by mass. Although the moisture content and temperature were measured by setting planned values in the same manner as in Example 2, the microwave was kept irradiated and the irradiation output was not controlled.

In Table 1, whitening, cracks, and cracks are evaluated by evaluating the proportion of 20 honeycomb structures in which whitening was observed. When whitening is 10%, it is shown that whitening was observed in two of the 20 honeycomb structures. The same applies to cracks and cracks.
In Example 1, there were four honeycomb structures in which an abnormality was recognized. Cracks and cracks were observed in all four bodies, and whitening was observed in two of these bodies. Of the 20 bodies, 16 bodies could be dried without abnormality and the yield was 80%.
In Example 2, there were two honeycomb structures in which abnormalities were recognized, and whitening, cracks, and cracks were observed in all of these. 18 out of 20 bodies could be dried without any abnormality, and the yield was 90%.
In Example 3, all the honeycomb structures could be dried without abnormality.
On the other hand, in Comparative Example 1, 16 honeycomb structures were found to be abnormal. In all of these, whitening and cracking were observed, and 14 of these were cracked.
As a result, by controlling the moisture content of the honeycomb structure, it was possible to suppress whitening, cracking, and cracking, and it was possible to dry well (Example 1). In addition to controlling the amount of water, Example 2 in which the temperature was further controlled could also be dried well. On the other hand, the honeycomb structure that did not control the microwave irradiation output had a moisture content and temperature exceeding the planned values, and many honeycomb structures with whitening, cracks, and cracks were observed, and the yield was low. (Comparative Example 1).
Moreover, since the frequency of the microwave is about 2450 MHz, the wavelength in the air is about 120 mm. Therefore, in the honeycomb structure of Example 3, the length of the side of the honeycomb surface is about 1.25 times (150 mm) the wavelength, and the height is about 1.25 times (150 mm). As a result, when a honeycomb structure having a large honeycomb structure whose side or height is at least 0.5 times the wavelength of the microwave is dried by microwaves, By protecting the sides with a covering material, it was possible to dry well without whitening, cracking or cracking, and the yield was 100% (Example 3).
FIG. 9 is a diagram showing the results of reducing the amount of water over time when the drying process of Example 1 was performed. Although the water content decreased gradually in the initial and final stages of the drying process, the water content decreased almost as planned. In the initial stage, it is considered that the time difference from the microwave irradiation to the evaporation of the water moderated the decrease in the water content. In the final stage, since the amount of water in the honeycomb structure is small, the decrease in the amount of volatilization is considered to have moderated the decrease in the amount of water.

Drying of honeycomb structure by continuous drying process [Example 4]
The honeycomb structure 1 (20 bodies) was continuously dried using a continuous drying apparatus shown in FIG. 3 until the moisture content became 10% by mass, and then the honeycomb structure The body 1 was evaluated for whitening, cracks and cracks.
The moisture content of the honeycomb structure 1 is measured using moisture measurement microwave oscillators 5a to 5d, and the honeycomb structure 1 (4a to 4 in FIG. 3) is output with a microwave in the same frequency band as the drying microwave at an output of 20 mW. This was performed by irradiating 4d) and measuring the microwave reflected from the honeycomb structure 1. Based on the result of the moisture content measurement, the microwave irradiation output was controlled so that the moisture reduction amount was 0.33 mass% / minute so that the drying could be completed in 1 hour.
The water content was determined to be a value that decreases with a decrease of 0.33 mass% / min. That is, the planned values at the start of the drying process, 30 minutes later, and at the end of the drying are 30% by mass, 20% by mass, and 10% by mass, respectively. When the moisture content of the honeycomb structure 1 was larger than the planned value, the irradiation output was increased, and when it was lower than the planned value, the irradiation output was decreased. When the water content was the planned value, the irradiation output amount was maintained, and when the water content became 10% by mass or less, the drying was finished.
The microwave irradiation output was controlled by turning on / off the power of the microwave irradiation apparatus. Referring to FIG. 3, for example, when the moisture content of the honeycomb structure 4a is measured by the moisture content measurement microwave oscillator 5b, only the microwave generator 3a that is irradiating the microwave is controlled according to the moisture content. Then, only 3b to be irradiated next was controlled, or both 3a and 3b were appropriately controlled.
The specification of the microwave irradiation device is that each of the microwave generators 3a to 3d has an output of 1 kW (variable continuously), frequency: 2450 ± 30 MHz, power input: three-phase alternating current, 200 V, microwave irradiation tank The specifications are: inner dimension: 600W × 700H × 1200L (mm), inner furnace material: SUS304. The speed of the conveyor was adjusted so that the honeycomb structure entered the microwave irradiation tank at the start of the drying process and exited from the microwave irradiation tank at the end of the drying process. In order to clarify the relationship between the control of the microwave irradiation output and the drying of the honeycomb structure, the drying treatment with hot air was not performed. The results are shown in Table 2.

[Example 5]
In the same manner as in Example 4, the honeycomb structure 1 (20 bodies) was placed in a continuous drying treatment apparatus and dried until the water content became 10% by mass. The moisture content was measured in the same manner as in Example 4, and the microwave irradiation output was controlled so that the amount of moisture reduction was 0.33 mass% / minute (planned value) so that the drying could be completed in 1 hour.
Further, using a non-contact type radiation thermometer (radiation thermometer 6 in FIG. 3), the temperature of the surface of the honeycomb structure 1 being dried is measured, and microwave irradiation is performed based on the temperature measurement result. The output was controlled. The temperature is a planned value in which the surface of each honeycomb structure 1 (4a to 4d in FIG. 3) is in the range of 80 ° C. to 100 ° C. The irradiation power of the microwave irradiated to the next or the microwave to be irradiated next is increased as appropriate, and when the temperature exceeds even 100 ° C., the microwave irradiated to the honeycomb structure or the next irradiated microwave The irradiation output of was decreased. When the temperature was the planned value, the irradiation output amount was maintained, and when at least 110 ° C. or higher, drying was interrupted by taking out the honeycomb structure or the like.
The microwave irradiation output was controlled by turning on / off the power of the microwave irradiation apparatus. Referring to FIG. 3, for example, when the temperature of the honeycomb structure 4a is measured by the radiation thermometer 6, only the microwave generator 3a that is irradiating the microwave is controlled according to the temperature, or the next 3b Only 3 or 3b and 3b were appropriately controlled.
In addition, when the part less than 80 degreeC and the part exceeding 100 degreeC coexisted in the honeycomb structure 1, irradiation output was reduced from a viewpoint which prevents whitening etc. from generating over the part over 100 degreeC.
In addition, when the water content was higher than the planned value and the temperature was higher than the planned value, the irradiation output was decreased in order to prevent whitening and the like from occurring. On the other hand, when the amount of water was less than the planned value and the temperature was lower than the planned value, the irradiation output was increased in order to shorten the drying time.

[Example 6]
In order to protect the corners and each side of the honeycomb structure 2, an aluminum tape having a thickness of 0.1 mm and a width A (FIG. 4) was coated as a covering material (FIG. 4). Then, in the same manner as in Example 4, the honeycomb structure 2 (20 bodies) was placed in a continuous drying treatment apparatus and dried until the water content became 10% by mass.

[Comparative Example 2]
Honeycomb structure 1 (20 bodies) was placed in the same continuous drying apparatus as in Example 4, and dried until the water content became 10% by mass. Although the moisture content and temperature were measured by setting planned values in the same manner as in Example 5, the microwave was kept irradiated and the irradiation output was not controlled.

In Example 4, there were two honeycomb structures in which an abnormality was observed. In all these two bodies, whitening, cracks and cracks were observed. Of the 20 bodies, 18 bodies could be dried without any abnormality, and the yield was 90%.
In Example 5, there was one honeycomb structure in which an abnormality was observed, and whitening, cracks, and cracks were observed in all of these. Nineteen out of 20 bodies could be dried without any abnormality, and the yield was 95%.
In Example 6, all the honeycomb structures could be dried without any abnormality.
On the other hand, in Comparative Example 2, 18 honeycomb structures were found to be abnormal. In all of these, cracks were observed, and 16 of these were whitened or cracked.
As a result, even in the continuous drying treatment, it was possible to suppress whitening, cracks and cracks by controlling the moisture content of the honeycomb structure, and it was possible to dry well (Example 4). In addition to controlling the amount of water, Example 5 in which the temperature was further controlled could also be dried well. On the other hand, the honeycomb structure that did not control the microwave irradiation output had a moisture content and temperature exceeding the planned values, and many honeycomb structures with whitening, cracks, and cracks were observed, and the yield was low. (Comparative Example 2).
In addition, a large honeycomb structure in which corners and sides were protected with a covering material could be dried well without causing whitening, cracking or cracking (Example 6).

Drying of honeycomb structure by humidity control drying process [Comparative Example 3]
The honeycomb structure 1 (20 bodies) was placed in a humidity control drying apparatus having a temperature of 30 ° C. and a humidity of 70% and dried until the moisture content became 10% by mass, and then the honeycomb structure 1 was whitened, cracked or cracked The presence or absence of was evaluated.

  If dried by the humidity control drying process, the honeycomb structure 1 is not whitened, cracked or cracked, and the yield of the drying process was 100%. It took a period of days and it was difficult to dry quickly.

  According to the method for drying a honeycomb structure of the present invention, it is possible to prevent generation of defective products and honeycomb structures that need to be re-dried, and it is possible to improve production efficiency by increasing yield. Therefore, it is useful industrially.

DESCRIPTION OF SYMBOLS 1 Continuous drying apparatus 2 Microwave irradiation tank 3a-3d Microwave generator 4a-4d Honeycomb structure 5a-5d Microwave oscillator for moisture content measurement 6 Radiation thermometer 7 Irradiation tank inlet 8 Irradiation tank outlet 9 Electromagnetic shutter 10 Conveyor 11 Hot air 12 Exhaust port 13 Honeycomb structure 14 Honeycomb surface 15 Aluminum tape 16a Corner 16b Side 17 Susceptor 18a Corner 18b Side 19 Bolt 20 Cylindrical end A Aluminum tape width A 'Aluminum tape width B Susceptor width

Claims (12)

A method for drying a honeycomb structure,
An irradiation drying step of drying the honeycomb structure by irradiating microwaves;
A moisture content monitoring step for monitoring the moisture content of the honeycomb structure;
A method for drying a honeycomb structure, comprising: a moisture amount control microwave irradiation output control step for controlling a microwave irradiation output in accordance with a moisture amount of the honeycomb structure.   The microwave irradiation output control step for moisture amount control is a step of controlling the microwave irradiation output so that the moisture reduction amount of the honeycomb structure is 0.2 to 1.0 mass% / min. The drying method of the honeycomb structure described.   The method for drying a honeycomb structure according to claim 1 or 2, wherein the moisture amount monitoring step includes a step of measuring the moisture amount by irradiating the honeycomb structure with a microwave for moisture amount measurement.   The method for drying a honeycomb structure according to any one of claims 1 to 3, wherein the moisture amount monitoring step includes a step of calculating a moisture amount by measuring a mass of the honeycomb structure. A temperature monitoring step for monitoring the temperature of the honeycomb structure;
The method for drying a honeycomb structure according to any one of claims 1 to 4, further comprising: a microwave irradiation output control step for temperature control that controls a microwave irradiation output in accordance with a temperature of the honeycomb structure.   The method for drying a honeycomb structure according to claim 5, wherein the microwave irradiation output control step for temperature control is a step of controlling the microwave irradiation output so that the temperature of the honeycomb structure becomes 80 ° C to 100 ° C. The irradiation drying step includes a step of irradiating the honeycomb structure with microwaves using a batch type drying apparatus to dry the honeycomb structure,
The batch-type drying apparatus includes at least a microwave irradiation tank, and the microwave irradiation tank includes at least one microwave irradiation apparatus that irradiates microwaves. Method for drying the honeycomb structure. The irradiation drying step includes a step of irradiating the honeycomb structure with microwaves using a continuous drying apparatus,
The continuous drying apparatus includes a microwave irradiation tank that includes a microwave generation apparatus that generates microwaves and irradiates and dries the honeycomb structure, and an irradiation that includes electromagnetic wave shutters installed before and after the microwave irradiation tank. At least a tank inlet and an irradiation tank outlet, and a transport device for carrying the honeycomb structure and sequentially transporting the irradiation tank inlet, the microwave irradiation tank, and the irradiation tank outlet are passing through the microwave irradiation tank. The method for drying a honeycomb structure according to any one of claims 1 to 6, wherein the honeycomb structure is an apparatus for irradiating the honeycomb structure with microwaves. The microwave irradiation tank includes a plurality of the microwave generators installed in parallel with the transport direction of the honeycomb structure,
The irradiation drying step includes a step of sequentially drying the honeycomb structure transported by the transport device by the plurality of microwave generators,
In the moisture amount control microwave irradiation output control step, the microwave generating apparatus that is drying the honeycomb structure and / or the microwave of the microwave generating apparatus that is subsequently dried according to the amount of water of the honeycomb structure is used. The method for drying a honeycomb structured body according to claim 8, further comprising a step of controlling the irradiation output of the honeycomb structure.   In the temperature control microwave irradiation output control step, the microwave irradiation of the honeycomb structure that is drying the honeycomb structure and / or the microwave generation apparatus that is dried next is performed according to the temperature of the honeycomb structure. The method for drying a honeycomb structure according to claim 8 or 9, comprising a step of controlling output. The honeycomb structure is a polygonal columnar honeycomb structure having a polygonal honeycomb surface,
The method according to claim 1, further comprising a covering step of covering at least the corners and each side of the surface of the honeycomb structure with a covering material that protects the honeycomb structure from microwaves before the irradiation drying step. The method for drying a honeycomb structure according to any one of the above. The honeycomb structure is a cylindrical honeycomb structure having a circular honeycomb surface,
Before the said irradiation drying process, The coating process which coat | covers the coating | coated material which protects a honeycomb structure from a microwave on the cylindrical end part of the surface of the said honeycomb structure is included in any one of Claims 1-10. The drying method of the honeycomb structure described.

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