JP2013169732A - Method and apparatus for drying green honeycomb molded object - Google Patents

Abstract

A method and apparatus for drying a green honeycomb molded body capable of suppressing deformation of the green honeycomb molded body during drying are provided.
A drying method according to the present invention is for drying a green honeycomb molded body having a plurality of through holes with a microwave and a heated gas, and the green honeycomb is formed on a gas dispersion plate capable of releasing the heated gas. At the same time as supplying the heated gas to which water vapor is added to each through hole of the green honeycomb molded body through the gas dispersion plate in an atmosphere in which water vapor exists around the green honeycomb molded body, and a preparation step for placing the molded body And a drying step of irradiating the green honeycomb molded body with microwaves.
[Selection] Figure 2

Description

  The present invention relates to a method for drying a green honeycomb molded body and a drying apparatus.

  A ceramic honeycomb structure having a large number of through-holes is produced by forming a green honeycomb formed body containing a ceramic raw material powder and a solvent, drying, and firing. Patent Document 1 below discloses a method using a microwave and heated gas as a method for drying a green honeycomb molded body.

Japanese translation of PCT publication No. 1-503136

  However, in the conventional method, the green honeycomb molded body may be deformed during drying. Therefore, an object of the present invention is to provide a drying method and a drying apparatus for a green honeycomb molded body that can suppress deformation of the green honeycomb molded body during drying.

  The present invention is a method for drying a green honeycomb molded body having a plurality of through holes with a microwave and a heated gas, and a preparation step of placing the green honeycomb molded body on a gas dispersion plate capable of releasing the heated gas; In the atmosphere where water vapor exists around the green honeycomb molded body, a heated gas to which water vapor is added is supplied to each through-hole of the green honeycomb molded body through the gas dispersion plate, and at the same time, microwaves are applied to the green honeycomb molded body. And a first drying step of irradiating.

  According to the above method, by supplying the heated gas to which water vapor is added to each through hole of the green honeycomb molded body to be dried, deformation of the green honeycomb molded body during drying can be suppressed. The heated gas is supplied to one end face of the green honeycomb molded body through the gas dispersion plate. According to the study by the present inventors, when the heated gas to which water vapor is not added is supplied to the green honeycomb molded body, the side to which the heated gas of the molded body is supplied (the one end face side) is locally early. The portion was easily heated and deformed easily. On the other hand, in the above method, since the heated gas to which water vapor has been added is supplied to the green honeycomb molded body, the heated gas supply side of the molded body can be prevented from being locally heated. Can be sufficiently suppressed.

  In the above method, after the first drying step, the addition of water vapor to the heated gas is stopped, and the heated gas is supplied to each through-hole of the green honeycomb molded body through the gas dispersion plate, and at the same time, the microwave is applied to the green honeycomb molded body. You may further provide the 2nd drying process which irradiates. After the green honeycomb molded body is heated sufficiently uniformly by the treatment in the first drying step, the moisture content of the green honeycomb molded body is sufficiently reduced by supplying a gas to which water vapor is not added and continuing the drying. it can. In order to further suppress the deformation of the green honeycomb molded body at the time of drying, the microwave output in the second drying step is preferably lower than the microwave output in the first drying step.

  The present invention also relates to a drying apparatus for a green honeycomb molded body having a plurality of through holes, a container, a microwave source that supplies a microwave into the container, and a heated gas source that supplies a heated gas into the container. A steam adding means for adding steam to the heated gas, a steam supply port for supplying steam into the container, and one of the end faces provided with a plurality of through-hole openings in the green honeycomb molded body in the container. And a gas dispersion plate for supplying heated gas from a heated gas source.

  According to the above apparatus, the heated gas to which water vapor has been added can be supplied to each through-hole of the green honeycomb molded body to be dried, and deformation of the green honeycomb molded body during drying can be suppressed.

  In the present invention, the microwave source is preferably capable of adjusting the output of the microwave. Moreover, it is preferable that the water vapor adding means can adjust the amount of water vapor added to the heated gas.

  ADVANTAGE OF THE INVENTION According to this invention, the drying apparatus and drying method of a green honeycomb molded object which can fully suppress the deformation | transformation of the green honeycomb molded object at the time of drying can be provided.

FIG. 1 is a drawing schematically showing an example of a green honeycomb molded body. 2A is a schematic cross-sectional view of the drying apparatus according to the first embodiment, and FIG. 2B is a perspective view of the seal member 80 of FIG. FIG. 3 is a schematic cross-sectional view of a drying apparatus according to the second embodiment. FIG. 4 is a top view of the mounting table 40 of the drying apparatus according to the second embodiment. FIG. 5A is a perspective view showing a state in which the green honeycomb molded body and the torch are integrated by the sealing member, and FIG. 5B is a perspective view showing the dried molded body and the torch. It is a graph which shows the dispersion | variation in the diameter of the green honeycomb molded object (after drying) which concerns on an Example. It is a graph which shows the dispersion | variation in the diameter of the green honeycomb molded object (after drying) which concerns on a comparative example.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings as necessary. However, the present invention is not limited to the following embodiments. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

(Green honeycomb molded body)
First, the green honeycomb molded body 70 to be dried will be described. As shown in FIG. 1, the green honeycomb molded body 70 is a column having a large number of through holes 71a and 71b extending from the upper end surface 70u to the other end surface 70d. The external shape of the green honeycomb molded body 70 is not limited to a cylindrical shape, for example, a regular polygonal column such as an elliptical column or a rectangular column (for example, a regular triangular column, a square column, a regular hexagonal column, a regular octagonal column, or a triangular column other than a regular polygonal column, A quadrangular prism, hexagonal prism, octagonal prism, etc.). The cross-sectional shape of the through holes 71a and 71b is not limited to a hexagon, and may be, for example, a polygon such as a circle, an ellipse, a square, a rectangle, a triangle, and an octagon. As shown in FIG. 1, the through-holes may have different diameters or different cross-sectional shapes, or may not be mixed.

  The length of the green honeycomb molded body 70 in the direction in which the through holes 71a and 71b extend is not particularly limited, but may be, for example, 40 to 350 mm. Further, the outer diameter of the green honeycomb molded body 70 is not particularly limited, but can be set to 100 to 320 mm, for example.

  As shown in FIG. 1, the plurality of through holes 71 a and 71 b are partitioned by a partition wall 72 that extends substantially parallel to the central axis of the green honeycomb molded body 70. The through-hole 71a has a regular hexagonal cross-sectional shape, and the through-hole 71b has a flat hexagonal cross-sectional shape and is formed so as to surround the through-hole 71a. The thickness (cell wall thickness) of the partition wall 72 is preferably 0.8 mm or less, more preferably 0.5 mm or less, preferably 0.1 mm or more, and more preferably 0.2 mm or more.

  The green honeycomb molded body 70 is green (unfired body) that becomes ceramics by firing later, and is particularly preferably green that becomes porous ceramics. Specifically, the green honeycomb molded body 70 includes a ceramic raw material. The ceramic is not particularly limited, and examples thereof include alumina, silica, mullite, cordierite, glass, oxides such as aluminum titanate, silicon carbide, silicon nitride, and metal. The aluminum titanate can further contain magnesium and / or silicon.

  The green honeycomb molded body 70 preferably includes an inorganic compound source powder that is a ceramic raw material, an organic binder such as methylcellulose, and an additive that is added as necessary.

  For example, when the ceramic is aluminum titanate, the inorganic compound source powder is aluminum source powder such as α alumina powder, titanium source powder such as anatase type or rutile type titania powder, and / or aluminum titanate powder. If necessary, a magnesium source powder such as magnesia powder and magnesia spinel powder and / or a silicon source powder such as silicon oxide powder and glass frit can be further contained.

  Examples of the organic binder include celluloses such as methylcellulose, carboxymethylcellulose, hydroxyalkylmethylcellulose, and sodium carboxymethylcellulose; alcohols such as polyvinyl alcohol; and lignin sulfonate. The amount of the organic binder is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and still more preferably 6 parts by weight with respect to 100 parts by weight of the inorganic compound source powder. Moreover, it is preferable that the minimum amount of an organic binder is 0.1 weight part, More preferably, it is 3 weight part.

  Examples of the additive include a pore-forming agent, a lubricant and a plasticizer, a dispersant, and a solvent.

  Examples of the pore-forming agent include carbon materials such as graphite; resins such as polyethylene, polypropylene, and polymethyl methacrylate; plant materials such as starch, nut shells, walnut shells, and corn; ice; and dry ice. The amount of pore-forming agent added is preferably 0 to 40 parts by weight, more preferably 0 to 25 parts by weight with respect to 100 parts by weight of the inorganic compound source powder.

  Examples of the lubricant include alcohols such as glycerin; higher fatty acids such as caprylic acid, lauric acid, palmitic acid, arachidic acid, oleic acid and stearic acid; and stearic acid metal salts such as Al stearate. The addition amount of the lubricant is preferably 0 to 10 parts by weight, more preferably 1 to 5 parts by weight with respect to 100 parts by weight of the inorganic compound source powder.

  As a plasticizer, polyoxyalkylene alkyl ether is mentioned, for example. The amount of the plasticizer is preferably 0.1 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, and still more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the inorganic compound source powder. 1 to 6 parts by weight.

  Examples of the dispersant include inorganic acids such as nitric acid, hydrochloric acid and sulfuric acid; organic acids such as oxalic acid, citric acid, acetic acid, malic acid and lactic acid; alcohols such as methanol, ethanol and propanol; ammonium polycarboxylate Surfactant etc. are mentioned. It is preferable that the addition amount of a dispersing agent is 0-20 weight part with respect to 100 weight part of an inorganic compound source powder, More preferably, it is 2-8 weight part.

  As the solvent, for example, alcohols such as methanol, ethanol, butanol and propanol; glycols such as propylene glycol, polypropylene glycol and ethylene glycol; and water can be used. Of these, water is preferable, and ion-exchanged water is more preferably used from the viewpoint of few impurities. The amount of the solvent used is preferably 10 to 100 parts by weight, more preferably 20 to 80 parts by weight with respect to 100 parts by weight of the inorganic compound source powder. The weight of the solvent relative to the total weight of the molded body is not particularly limited, but is preferably 10 to 30% by weight, and more preferably 15 to 20% by weight.

  Such a green honeycomb molded body 70 can be manufactured as follows, for example. First, an inorganic compound source powder, an organic binder, a solvent, and additives to be added as necessary are prepared. Then, these are mixed by a kneader or the like to obtain a raw material mixture, and the obtained raw material mixture is extruded from an extruder having an outlet opening corresponding to the cross-sectional shape of the green honeycomb molded body, and cut into a desired length, A green honeycomb molded body 70 can be obtained.

<First Embodiment>
(Drying device)
The drying apparatus 100 according to the present embodiment is for drying the green honeycomb molded body 70, and mainly includes a container 10, a microwave source 20 that supplies a microwave into the container 10, and a mounting disposed in the container 10. A mounting table 40, a heating gas source 30 for supplying a heating gas to the plurality of through holes 71a and 71b of the green honeycomb molded body 70 via the gas dispersion plate 42 of the mounting table 40, and a steam supply line for adding steam to the heating gas (Water vapor adding means) L1 and a sealing member 80 for preventing the heated gas from being applied from the gas dispersion plate 42 to the outside of the green honeycomb molded body 70 are provided.

  The container 10 can accommodate the green honeycomb molded body 70, the mounting table 40, and the outlet portion 36 a of the pipe line 36. The container 10 is preferably made of metal from the viewpoint of shielding microwaves. The container 10 is provided with a discharge port 10b for discharging the gas in the container 10 to the outside. In addition, the container 10 includes a waveguide 10 a that receives a microwave supplied from the microwave source 20.

  The microwave source 20 generates a microwave for heating the green honeycomb molded body 70. The wavelength of the microwave is not particularly limited as long as the green honeycomb molded body 70 can be heated. Preferred wavelengths are 895 to 940 MHz and 2400 to 2500 MHz. The microwave source 20 is preferably capable of adjusting the output of the microwave, and can be reduced as it is dried, for example. Although the microwave output is not particularly limited, the microwave output per unit weight of the green honeycomb molded body is preferably 0.2 to 4 kW / kg, more preferably 1 to 3 kW / kg.

  The mounting table 40 is a table that is disposed in the container 10 and on which the green honeycomb molded body 70 is mounted. The mounting table 40 includes a gas dispersion plate 42 and a non-breathable ring member 44 surrounding the side surface of the gas dispersion plate 42. The green honeycomb molded body 70 is placed on the gas dispersion plate 42 such that one end surface (lower surface) 70d provided with openings of the plurality of through holes 71a and 71b is opposed to the upper surface of the gas dispersion plate 42. Is done. In the present embodiment, the size of the upper surface (gas release region) of the gas dispersion plate 42 is equal to the size of the end surface 70d of the green honeycomb molded body 70, but is slightly larger than the end surface 70d. Also good.

  The gas dispersion plate 42 is a plate having a plurality of holes communicating with the front and back, and makes the gas flow in the in-plane direction uniform when the gas supplied from below passes upward. The gas dispersion plate 42 may be a so-called perforated plate (for example, a honeycomb lattice shape similar to that of a green honeycomb molded body) in which a large number of holes penetrating the front and back are formed, but may be configured to release gas upward. For example, a so-called porous plate having a large number of pores that communicate with each other and are bent may be used.

  The material of the gas dispersion plate 42 is also not particularly limited, and examples thereof include ceramics such as alumina and cordierite. The thickness of the gas dispersion plate 42 can be set to 10 to 100 mm, for example. The planar shape of the holes when the gas dispersion plate 42 is a perforated plate is not limited, and may be, for example, a square, a circle, a hexagon, or an octagon. For example, when the shape is a square, the diameter of the hole can be set to a length of one side of 0.7 to 10 mm. Moreover, the thickness of the wall between holes can be 0.03-3.0 mm, for example. On the other hand, the average pore diameter when the gas dispersion plate 42 is a porous plate is not particularly limited, but is preferably 0.1 to 100 μm. The average pore diameter can be measured by a mercury intrusion method. The porosity is preferably 10 to 90%. In addition, the porous plate comprised from the porous plate may be sufficient.

  The ring member 44 surrounds the side surface of the gas dispersion plate 42 and prevents gas leakage from the side surface.

  The heating gas source 30 heats the gas flowing in the pipe 36 by being provided in the blower 32 disposed outside the container 10, the pipe 36 that guides the gas from the blower 32 to the lower surface of the gas dispersion plate 42, and the pipe 36. The heater 34 is provided. Although the heating temperature of gas is not specifically limited, 30-200 degreeC is preferable and 40-100 degreeC is more preferable. The gas is not particularly limited, but air is preferable from the economical viewpoint. The amount of gas supply is also not particularly limited, but the area average gas wind speed immediately above the gas dispersion plate 42 is preferably 0.1 to 10 m / s, and more preferably 0.5 to 5 m / s. It is more preferable.

  The outlet 36 a of the pipe 36 has a diameter that increases in accordance with the area of the lower surface of the gas dispersion plate 42, and is in contact with the lower surface of the ring member 44. A steam supply source is connected to the middle of the pipeline 36 via a steam supply line L1, so that steam can be added to the heated gas. The amount of water vapor supplied through the water vapor supply line L1 can be adjusted. As conditions for steam supplied through the steam supply line L1, for example, the temperature is preferably 100 to 200 ° C., and the supply amount W1 is preferably 0.1 to 30 kg / hr with respect to the unit weight of the green honeycomb molded body.

  A steam supply port 10 c is formed on the wall of the container 10. A steam supply source is connected to the steam supply port 10c via a steam supply line L2, and steam is supplied into the container 10 so that each green honeycomb molded body is maintained in an atmosphere in which steam exists. Can do. It is preferable to supply from the line L2 an amount of water vapor that saturates the container 10. By making the inside of the container 10 a high-humidity environment, deformation of the green honeycomb molded body, particularly deformation at the initial stage of drying can be suppressed. As conditions for water vapor supplied through the water vapor supply line L2, for example, the temperature is preferably 100 to 200 ° C., and the supply amount W2 is preferably 0.1 to 30 kg / hr with respect to the unit weight of the green honeycomb molded body. The ratio (W1 / W2) of the amount of water vapor supplied through each of the water vapor supply lines L1 and L2 is preferably 0.2 to 5.0, more preferably 0.5 to 2.0.

  The seal member 80 is a member for preventing the heated gas from the gas dispersion plate 42 from hitting the outer peripheral wall of the green honeycomb molded body 70. The seal member 80 is disposed so as to cover the outside of the lower end portion of the green honeycomb molded body 70 and the peripheral edge portion of the gas dispersion plate 42.

  The sealing member 80 is preferably made of a material that can follow the shrinkage associated with the drying of the green honeycomb molded body 70. Examples of such materials include silicone rubber and fluorine rubber. When the seal member 80 is made of the above-described cylindrical material, when arranged as shown in FIG. 2A, the portion 80a extending in the axial direction (Z direction) and the direction perpendicular to the Z direction (XY plane) are arranged. An expanding portion 80b is formed. Alternatively, the cylindrical seal member 80 may be processed to previously form a portion 80a extending in the Z direction and a portion 80b extending in the horizontal direction in the axial direction.

  In order to prevent the green honeycomb formed body 70 from being deformed by being loaded from the seal member 80, the inner diameter D1 when the portion 80a extending in the Z direction is not attached is larger than the outer diameter D2 when the green honeycomb formed body 70 is dried. Is preferably slightly smaller, and the difference (D2−D1) may be about 1 to 20 mm. For example, when the diameter of the green honeycomb molded body 70 is 150 mm, the inner diameter of the seal member 80 is preferably about 140 to 130 mm. The length L80b in the Z direction of the seal member 80 is not particularly limited, but may be 1 to 100 mm. The thickness of the sealing member 80 can be 0.5-5 mm, for example.

(Drying method)
Then, the drying method of the green honeycomb molded object concerning this embodiment is demonstrated. First, as shown in FIG. 2A, the base end side (part 80 a) of the seal member 80 is attached to the outside of one end portion of the green honeycomb molded body 70, and the upper surface of the gas dispersion plate 42 of the container 10. The green honeycomb molded body 70 is placed so that the end faces 70d face each other (preparation step). At this time, the front end side (part 80 b) of the seal member 80 is expanded so as to cover the peripheral edge of the gas dispersion plate 42.

  Subsequently, the blower 32 is activated and the heater 34 is activated. Further, a microwave is supplied from the microwave source 20 into the container 10. Further, water vapor is continuously supplied from the water vapor supply port 10c into the container, so that each green honeycomb molded body 70 has an atmosphere in which water vapor exists.

  When the surroundings of the green honeycomb molded body 70 are in a state where water vapor is present, steam is continuously supplied into the pipe 36 through the water vapor supply line L1, and the heated gas is supplied to the lower surface of the gas dispersion plate 42. Supply. The heated gas to which water vapor has been added passes through the gas dispersion plate 42, passes through the through holes 71 a and 71 b of the green honeycomb molded body 70, and is discharged from the upper end surface 70 u of the green honeycomb molded body 70. It is discharged from the discharge port 10b. Further, the green honeycomb molded body 70 is irradiated with microwaves.

  By such heating and gas supply, the solvent component of the green honeycomb molded body 70 is removed, and drying proceeds (first drying step). Although depending on the output of the microwave and the supply amount of water vapor, the first drying step is preferably performed for 1 to 10 minutes. Thereafter, the addition of water vapor to the heated gas is stopped, and the heated gas (gas to which no water vapor is added) is supplied to each through-hole of the green honeycomb molded body 70 through the gas dispersion plate 42, and at the same time, A wave may be irradiated (second drying step). It is preferable to implement a 2nd drying process over 1 to 10 minutes. In addition, it is preferable to transfer to the 2nd drying process from the 1st drying process in the stage in which the temperature of the green honeycomb molded object 70 became 80-130 degreeC as a whole.

  As the drying progresses, for example, when shifting from the first drying process to the second drying process, it is preferable to reduce the output of the microwave supplied from the microwave source 20. This has the effect of suppressing runaway (ignition) due to local temperature rise due to overdrying. The degree of final drying of the molded body, which is reached by drying by supplying heated gas and microwaves in a steam atmosphere, is not particularly limited, but when the supply of microwaves and water vapor is stopped, the drying rate of the molded body, That is, the ratio of the solvent mass removed by drying to the solvent mass before drying of the molded body is preferably 80% or more, more preferably 90% or more, and further preferably 95% or more. In addition, after stopping supply of a microwave and water vapor | steam, it is also preferable to advance drying by flowing only heated gas.

  According to the present embodiment, by supplying the heated gas to which water vapor is added to the through holes 71a and 71b of the green honeycomb molded body 70, the side to which the heated gas is supplied (the other end surface 70d side) is locally provided. Heating can be suppressed. Thereby, the deformation | transformation of the green honeycomb molded object 70 at the time of drying can be suppressed.

  Further, by using the sealing member 80 capable of following the contraction of the green honeycomb molded body 70, it is possible to sufficiently prevent the heated gas from leaking outside the green honeycomb molded body 70 being dried (see FIG. 5). It can prevent more reliably that the outer peripheral wall of the molded object 70 dries excessively. Further, the use of the seal member 80 can effectively prevent the following problems. That is, when the opening areas of the through holes 71a and 71b of the green honeycomb molded body 70 are relatively small, if the gas discharge area of the gas dispersion plate 42 is exposed as the green honeycomb molded body 70 contracts, a large amount of heat is generated from the areas. The gas flows to the outside of the molded body 70, and the amount of gas flowing through the through holes 71a and 71b decreases. In such a situation, the inside of the molded body 70 becomes insufficiently dried, and problems such as cell crushing and cracking of the molded body occur in a process (for example, a cutting process) after drying. According to the present embodiment, the yield can be improved by sufficiently reducing such problems.

  The ceramic honeycomb structure is obtained by sealing the end portions of the through holes 71a and 71b of the green honeycomb molded body 70 thus dried, if necessary, and then firing. Such a ceramic honeycomb structure can be used as a diesel particulate filter or a catalyst carrier for an exhaust gas treatment apparatus.

Second Embodiment
Subsequently, a drying apparatus 200 according to the second embodiment will be described with reference to FIGS. 3 and 4. In the present embodiment, only differences from the first embodiment will be described, and overlapping descriptions will be omitted. The drying apparatus 200 according to this embodiment is for drying two green honeycomb molded bodies 70 simultaneously.

  In the present embodiment, as shown in FIG. 3, the mounting table 40 includes two gas dispersion plates (gas outlets) 42 and a non-breathable ring member 44 surrounding the side surfaces of the two gas dispersion plates 42. The outer shape is a disk shape. The two green honeycomb molded bodies 70 are mounted on the gas dispersion plates 42 so that one end surfaces (lower surfaces) 70d provided with openings of the plurality of through holes 71a and 71b are opposed to the upper surfaces of the respective gas dispersion plates 42. The sealing member 80 covers the outside of the lower end portion of the green honeycomb molded body 70 and the peripheral edge portion of the gas dispersion plate 42. Each gas dispersion plate 42 and the seal member 80 are the same as those in the first embodiment. The two gas dispersion plates 42 have a distance D between the green honeycomb molded bodies 70 placed on these gas dispersion plates 42, when the wavelength of the microwave supplied from the microwave source 20 is λ. They are arranged to exceed 2λ.

  A vertical shaft 52 is provided on the lower center surface of the mounting table 40, and the vertical shaft 52 can be rotated by a motor 50. Thereby, the mounting table 40 can be rotated around the vertical axis in the container 10. Although the rotation speed is not particularly limited, it can be 1 to 60 rpm.

  A steam supply source is connected to the middle of the pipe line 36 via a steam supply line L1. As shown in FIGS. 3 and 4, the outlet 36 a of the conduit 36 is provided with an opening 36 ab that faces upward and has a ring shape when viewed from above. The tip 36ae of the outlet portion 36a is in contact with the lower surface of the ring member 44 as shown in FIG. Since the outlet portion 36a has the ring-shaped opening 36ab facing upward, the heated gas can be supplied to the gas dispersion plate 42 serving as a gas outlet regardless of the rotation position of the mounting table 40 that rotates. Via the through holes 71a and 71b of each green honeycomb molded body 70. The distal end 36ae of the outlet portion 36a can be brought into contact with the lower surface of the ring member 44 while sliding, and gas sealing is possible.

  According to this embodiment, there exists an effect similar to 1st Embodiment. Further, since the distance D between the green honeycomb molded bodies 70 is more than half of the microwave wavelength λ, the microwaves can sufficiently wrap around the green honeycomb molded bodies 70 and the two molded bodies are uneven. And easy to dry.

  Further, when a plurality of green honeycomb molded bodies 70 are dried at a time in such a drying apparatus 200, microwaves can be used efficiently. Therefore, the microwave output and heating gas supply per green honeycomb molded body 70 are supplied. When the amount is the same, the drying time can be shortened as compared with the case of drying alone. Note that a fixture 85 for fixing the green honeycomb molded body 70 may be provided on the mounting table 40.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the surface of the gas dispersion plate 42 is horizontally arranged, and the green honeycomb molded body 70 is held by placing the green honeycomb molded body 70 on the upper surface of the gas dispersion plate 42. It is not limited. For example, the surface of the gas dispersion plate 42 may be arranged vertically, and the green honeycomb molded body 70 may be held by another holding member so that the end face 70d of the green honeycomb molded body 70 is in contact with the vertical surface.

  In the second embodiment, two gas dispersion plates 42 are provided on the mounting table 40, two green honeycomb molded bodies 70 are placed on the gas dispersion plates 42, and these molded bodies are attached at a time. Although dried, three or more green honeycomb molded bodies 70 may be dried at a time by providing three or more gas dispersion plates.

  In the above-described embodiment, the case where the sealing member 80 having flexibility is used as a particularly preferable example. However, if the deformation of the green honeycomb molded body in the initial stage of drying is simply prevented, An annular plate that covers the exposed portion may be used as a seal member, and the seal member may not be used depending on the size of the gas dispersion plate 42.

  Moreover, in the said 2nd Embodiment, implementation is possible even if the space | interval between the two green honeycomb molded objects 70 is 1/2 or less of the wavelength (lambda) of a microwave.

  Also, instead of the gas dispersion plate 42 or on the gas dispersion plate 42, a firing table having the same composition and through-hole structure as the green honeycomb molded body 70 is provided, and a green honeycomb molded body 70 is mounted thereon. It may be placed. In this case, as shown in FIG. 5A, the torch 42a, the green honeycomb molded body 70, and the seal member 80 may be integrated in advance and placed on the gas dispersion plate 42. By using a material made of a material that can follow the shrinkage of the green honeycomb molded body as the sealing member 80, the peripheral portion (exposed gas release region) of the torch 42 a is sealed as shown in FIG. The state covered with can be maintained.

<Example>
(Manufacture of green honeycomb molded body)
The following components were mixed to prepare clay (molding raw material mixture). Incidentally, ceramic powder, below, with a composite phase of aluminum magnesium titanate and alumina and aluminosilicate glass (charging time of the composition formula: 41.4Al ₂ O ₃ -49.9TiO ₂ -5.4MgO- 3.3SiO ₂ , the numerical value in the formula represents the molar ratio.)
Al ₂ O ₃ powder: 37.3 parts by mass
TiO ₂ powder: 37.0 parts by mass,
MgO powder: 1.9 parts by mass
· SiO ₂ powder: 3.0 parts by weight,
-Ceramic powder: 8.8 parts by mass,
-Pore forming agent (potato starch with D50 of 25 μm): 12.0 parts by mass,
Organic binder 1 (methyl cellulose (trade name MC-40H)): 5.5 parts by mass
Organic binder 2 (hydroxypropylmethylcellulose (trade name PMB-40H)): 2.4 parts by mass
Plasticizer 1 (glycerin): 0.4 parts by mass
Plasticizer 2 (polyoxyethylene polyoxypropylene butyl ether): 4.6 parts by mass
-Water: 28.4 mass parts.

  A plurality of green honeycomb molded bodies were produced by extruding the kneaded material. The green honeycomb molded body was a column (240 mm in length) having a large number of through-holes in the embodiment shown in FIG.

The green honeycomb molded body was dried with the drying apparatus shown in FIG. That is, a state in which a sealing member (thickness: 1 mm, length: 10 mm, material: silicone rubber) having an inner diameter slightly smaller than the diameter of the green honeycomb molded body is mounted on the green honeycomb molded body as shown in FIG. And dried.
Drying conditions were as follows.
Specifications of gas dispersion plate: material: alumina, thickness: 40 mm, the planar shape of the hole is a square with a side of 5.2 mm, and a wall thickness of 1.1 mm.
The microwave frequency was 2.45 GHz, and the microwave output was 24 kW from 0 to 5.5 minutes drying time and 14.4 kW from 5.5 to 11 minutes.
The supply gas was air, and the heating temperature of the supply gas was 40 ° C. The amount of gas supply was set so that the area average gas wind speed of the gas dispersion plate immediately above the gas dispersion plate was 0.5 m / s. The temperature of water vapor supplied to the outside of the green honeycomb molded body was 120 ° C., and the supply amount was 0.35 kg / min per unit weight of the green honeycomb molded body. The temperature of water vapor added to the heated gas supplied into the green honeycomb molded body was 120 ° C., and the supply amount was 0.35 kg / min with respect to the unit weight of the green honeycomb molded body. The microwave irradiation time was from time 0 to 11 minutes, the water vapor supply time was from time 0 to 5.5 minutes, and the heated gas was supplied from time 0 to 11 minutes.

No deformation or cracking was observed in the green honeycomb molded body of the example. The drying rate of the green honeycomb molded body was 91.9%. The drying rate is a value calculated by the following formula based on the values of the weight before drying and the weight after drying of the green honeycomb molded body.
Drying rate (%) = (weight before drying−weight after drying) / (weight before drying × moisture content) × 100

<Comparative example>
The green honeycomb molded body was dried in the same manner as in the example except that water vapor was not added to the heated gas supplied into the green honeycomb molded body. The drying rate of the green honeycomb molded body was 92.0%.

  Both ends of the dried green honeycomb molded body were cut with a band saw to a length of 170 mm. 6 and 7 are graphs showing the diameters (relative values) of the green honeycomb molded bodies after drying in Examples and Comparative Examples, respectively. The operation of measuring the diameter in a state where the dried green honeycomb molded body was placed on the turntable, and then measuring the diameter again by rotating the angle by 15 ° was repeated 24 times. Furthermore, this was carried out at 10 places with different heights. As shown in FIGS. 6 and 7, the green honeycomb molded body of the example has smaller diameter variation than the green honeycomb molded body of the comparative example.

Table 1 shows the squareness, roundness, and cylindricity of the green honeycomb molded bodies after drying in Examples and Comparative Examples, respectively. These values are obtained as follows, and in each case, the smaller the value, the closer the outer shape of the green honeycomb molded body after drying is to a cylinder.
(right angle)
With the green honeycomb molded body standing, 24 points are measured at a 15 ° pitch in the circumferential direction on the longitudinal section, and the vertical line and the value that gives the maximum displacement on the reference plane (the lower end surface of the green honeycomb molded body) are measured. The squareness (mm) was used.
(Roundness)
The difference between the maximum value and the minimum value of the diameter was calculated at 10 points with different heights, and the maximum value of the difference was defined as the roundness.
(Cylindrical degree)
A figure consisting of all deviations of each face center-corrected by the circle, passing through the center of the circle where the sum of squares of the measurement deviation of the lower end face is the minimum and having a line perpendicular to the turntable plane as the axis. The radius difference between the two cylinders inscribed and circumscribed is defined as cylindricity.

DESCRIPTION OF SYMBOLS 10 ... Container, 20 ... Microwave source, 30 ... Heated gas source, 42 ... Gas dispersion plate, 42a ... Tochi (gas dispersion plate), 70 ... Green honeycomb molded object, 70d ... Other end surface, 70u ... Upper end surface, 71a, 71b ... through-hole, 100, 200 ... drying device, L1 ... steam supply line (steam addition means), L2 ... steam supply line.

Claims (6)

A method of drying a green honeycomb molded body having a plurality of through holes with a microwave and a heated gas,
A preparatory step of placing the green honeycomb molded body on a gas dispersion plate capable of releasing heated gas;
In an atmosphere where water vapor is present around the green honeycomb molded body, a heated gas added with water vapor is supplied to each through-hole of the green honeycomb molded body through the gas dispersion plate, and at the same time, the green honeycomb molded body is supplied to the green honeycomb molded body. A first drying step of irradiating microwaves;
A method comprising:   After the first drying step, the addition of water vapor to the heated gas is stopped, the heated gas is supplied to each through-hole of the green honeycomb molded body through the gas dispersion plate, and at the same time, The method according to claim 1, further comprising a second drying step of irradiating with waves.   The method according to claim 1, wherein the microwave output in the second drying step is lower than the microwave output in the first drying step. A device for drying a green honeycomb molded body having a plurality of through holes,
A container,
A microwave source for supplying microwaves into the container;
A heated gas source for supplying heated gas into the container;
Water vapor addition means for adding water vapor to the heated gas;
A water vapor supply port for supplying water vapor into the container;
In the container, a gas dispersion plate that supplies heated gas from the heated gas source to one of the end surfaces of the green honeycomb molded body provided with openings of the plurality of through holes,
A device comprising:   The apparatus of claim 4, wherein the microwave source is capable of adjusting a microwave output.   The apparatus according to claim 4 or 5, wherein the water vapor adding means is capable of adjusting an amount of water vapor added to the heated gas.

Images