JP7806353B2 - Vibration treatment device and treatment method using said device - Google Patents

Description

The present invention relates to a vibration processing device such as a vibration dryer or a vibration fluidizer, and a processing method using the device, in which the raw material to be fed into a processing vessel is a powder or granular material or a powder-containing raw material in a slurry or paste form. Note that, although the raw material (dispersoid) in the present invention is primarily a dielectric, in the case of a drying process in which liquid components such as water are evaporated, a non-dielectric (conductor) such as a metal can also be applied, and the present invention can also be applied to a fluidized solid-state reaction.

Here, we will mainly use a vibration dryer, particularly a vertical vibration dryer, as an example of a vibration treatment device, but the same applies to horizontal vibration dryers and vibration fluidizers (for example, Patent Documents 1 and 2).

The present applicant has marketed vibration dryers such as vertical "batch VU type," "vibration evaporator," and "vibration fluidized disperser," as well as horizontal "batch VH type," "continuous VHC type," and "slurry feed VHS" that are capable of processing a variety of forms of raw materials, from powdered and granular materials to slurry and paste-like powdered and granular materials (Non-Patent Document 1). Patent documents related to vertical vibration dryers filed by the present applicant include Patent Documents 3 to 6.

The present inventors are not aware of any vibration dryers or vibration fluidizers that are equipped with a microwave generator capable of irradiating microwaves through a waveguide within a processing vessel. Patent Document 6 [0028] discloses that the heating means is not limited to jacket heating as in the embodiment, but that a microwave generator (magnetron) can be attached to the ceiling of the processing vessel in combination with microwave heating. However, this document intends to attach the microwave generator (magnetron) directly to the ceiling, and is therefore unconventional in that it does not anticipate irradiating a specific portion of the raw material with microwaves from the waveguide of the present invention. Furthermore, attaching a microwave generator directly to the ceiling of the processing vessel is believed to shorten the magnetron's lifespan, and has not been put to practical use.

Furthermore, Patent Documents 7 and 8 are known documents that describe microwave (reduced pressure) dryers equipped with a microwave oscillator and capable of irradiating microwaves into a drying treatment container. However, in Patent Documents 7 and 8, the treatment container is stationary, and the raw materials (materials to be dried) are all food products (vegetables, fruits, seaweed, meat, etc. (Patent Document 7 [Claim 9], Patent Document 8 [0032]). They do not anticipate vibration treatment as in the present invention, nor do they anticipate powdery or granular materials or powder-containing raw materials in a slurry or paste form. Furthermore, to uniformly irradiate the raw materials with microwaves, a rotating table or a stirring fan for rotating the drying tray is required (Patent Document 7 [0052], Patent Document 8 [0031]).

In view of the above, the present inventors have conceived of a vibration treatment device having the following configuration and previously filed an application (Patent Application No. 2021-100522 (Patent Publication No. 2022-173013); hereinafter referred to as the "prior application") with the aim of providing a new vibration treatment device that does not pose a risk of shortening the lifespan of the oscillator (magnetron), does not require equipment such as a rotary table or stirrer fan, and is expected to significantly improve microwave irradiation efficiency.

A vibration treatment device equipped with a vibration means for vibrating a treatment vessel, wherein the raw material is a powder or granular material or a powder-containing raw material in a slurry or paste form, and the vibration means causes the raw material introduced into the treatment vessel to rise and fall along the wall of the treatment vessel,
The method is characterized in that a microwave transmitter is attached, the microwave emission port of the microwave generator is connected to a microwave irradiation port formed in the processing container via a flexible waveguide member, and the processing container is further equipped with a steam suction means.

Japanese Patent Application Laid-Open No. 2006-95437 Japanese Patent Application Publication No. 7-4834 JP 2017-90029 A JP 2011-7368 A JP 2009-68740 A Japanese Patent Application Publication No. 11-153384 Japanese Patent Application Laid-Open No. 2020-190338 JP 2013-194966 A

Chuo Kakoki, "Vibration Dryer," Chuo Kakoki Catalog, pp. 3, 6-11, June 2018 (also available from the Chuo Kakoki website: https://www.chuokakohki.co.jp) Chuo Kakoki, "Corporate Profile; Powder & Chemical Plant," Chuo Kakoki Catalog, Dryer section (pp. 10, 11), July 2017

The vibration treatment device described above typically comprises a steel processing vessel equipped with a heating (temperature-controlling) jacket mounted on a steel vibration table. To prevent contamination (associated with corrosion of the inner wall), at least the powder-contacting portion of the processing vessel body is formed of a corrosion-resistant material such as stainless steel, Hastelloy (a Ni-based corrosion-resistant alloy: a registered trademark), or titanium (Non-Patent Document 2, p. 10). These corrosion-resistant materials are all made of metals with good heat conductivity to ensure heat transfer from the jacket. To further prevent contamination, the powder-contacting portion of the processing vessel may be coated with Teflon (a registered trademark), but this coating cannot be made thick enough due to the heat transfer characteristics and its low hardness makes it unsuitable for raw materials containing highly hard inorganic substances.

Furthermore, recently, there has been a growing demand for stricter tolerances for contaminant content in vibration (drying) processed products (e.g., from ppm to ppb), particularly for reducing the tolerance for contaminant content such as metal powder. In other words, there is a growing demand for even higher purity (fineness) of processed products. However, the inventors are unaware of any vibration processing device or vibration processing method that can meet this demand. Although PTFE has a significantly lower coefficient of friction than other resins and is highly abrasion-resistant, its hardness is low, and depending on the raw material (e.g., high hardness), it may be scratched, making contamination unavoidable.

In view of the above, an object (object) of the present invention is to provide a vibration treatment device and a vibration treatment method that can meet the demand for even higher purity of treated products (particularly, a reduction in the allowable content of metal contaminants).

In order to solve the above problems, the inventors focused on the microwave heating type vibration treatment device of the prior application and made intensive efforts in development, and as a result, came up with the vibration treatment device and vibration treatment method of the following configuration, in which at least the powder contact part is made of a dielectric layer that is not substantially heated by microwaves.

A vibration treatment device equipped with a vibration means for vibrating a treatment vessel, wherein the raw material is a powder or granular material or a powder-containing raw material in a slurry or paste form, and the vibration means causes the raw material introduced into the treatment vessel to flow upward and downward along the wall of the treatment vessel,
a microwave generator is provided, and an output port of the microwave generator is connected to a microwave irradiation port formed in the processing vessel via a flexible waveguide member; and
the processing vessel is provided with a vapor exhaust means, and at least a raw material contact portion of an inner surface of the processing vessel during operation is made of a dielectric layer;
The dielectric layer is characterized in that it is formed from a polymeric or ceramic material that satisfies both of the following characteristics: a relative dielectric constant ( _εr ) of 10 or less and a loss angle (tanδ) of 0.08 or less (both at a frequency of 2.45 GHz and 25°C; the same applies below).

Here, the ranges of the relative permittivity ( _εr ) and dielectric loss angle (dielectric tangent) (tanδ) of the material forming the dielectric layer are determined based on Figure 2 (quoted from "Microwave Oven/Microwave Usage Handbook" edited by Atsuko Higo, Japan Industrial Newspaper, 1987, p. 16), and are the ranges considered to be substantially difficult to microwave heat, i.e., the loss factor ( _εr ·tanδ). In other words, the difficulty to microwave heat is determined as the range in which the loss factor is small. The desirable range is a tanδ of 0.02 or less, preferably 0.002 or less, and even more preferably 0.0002 or less.

The above-mentioned configuration can solve the above-mentioned problem (demand for further high purity of the processed product (particularly, reduction of the allowable content of metal contaminants)).

When the dielectric layer is made of a polymeric material, even if polymeric wear particles are mixed in, they can be eliminated by heating, volatilizing, and incinerating the polymeric wear particles contained in the product, as in the vibration treatment method of the present invention. The polymeric material may be resin or rubber as long as it satisfies the above-mentioned properties, or may be inorganic polymer or reinforced resin (FRP, etc.) as long as it satisfies the above-mentioned dielectric properties.

Although the resin may be polyamide or the like, a thermoplastic resin that is relatively resistant to heat generation by microwaves, i.e., a low-polarity thermoplastic resin, is preferable. Examples of such thermoplastic resins include crystalline polypropylene (crystalline PP), high-density polyethylene (high-density PE), and polytetrafluoroethylene (PTFE). Of these, crystalline PP is preferable because it has superior mechanical properties compared to high-density PE and superior flammability compared to PTFE.

When the dielectric layer is made of a ceramic material, it is possible to use a material with a much higher hardness than metal (for example, alumina: 15-18 Hv, while SUS304: 2 Hv). This significantly reduces the generation of wear particles at the raw material contact area (powder contact area). Note that ceramic materials include not only inorganic oxides such as alumina and zirconia, but also nitrides, carbides, borides, or composite compounds containing these.

In the above configuration, the thickness of the dielectric layer varies slightly depending on the constituent material, but is usually 0.5 to 5 mm, preferably 0.5 to 2.5 mm. If the thickness is too thin, it will wear out quickly, its service life will be short, and maintenance will be difficult. On the other hand, if the thickness is too thick, it will be excessive in quality and will increase in weight or reduce the processing volume, which is undesirable.

In the vibration treatment device having the above configuration, it is desirable that the dielectric layer be configured as a cartridge container that can be attached to and detached from the treatment container body. This makes it easy to load raw materials and unload products, and if the cartridge container is a disposable type made of thermoplastic resin such as PP, it becomes possible to simultaneously heat and volatilize the organic polymer wear powder and incinerate the cartridge container.

The vibration treatment device configured as described above does not usually require a temperature-controlled jacket, and can even be used for atmospheric pressure or low vacuum treatment. The temperature-controlled jacket is not necessary because microwave heating allows selective heating based on differences in loss factors. If the loss factor of the raw material (powder) is small, only the droplets (water droplets) adhering to the powder, which have an extremely large loss factor, can be heated during vibration treatment, allowing the raw material to be dried efficiently. Furthermore, there is no need to create a high vacuum inside the treatment vessel to promote evaporation. Therefore, there is no need for a temperature control mechanism such as a temperature-controlled jacket, a suction means for creating a high vacuum, or a high-level seal for the treatment vessel. As a result, the additional costs associated with microwave heating can be reduced.

It should be noted that the present invention employs various configurations of conventional and prior application vibration treatment devices (vibration drying devices) in which the powder-contacting portion of the treatment container is not a dielectric layer, and of course exhibits the effects of these configurations (see prior application specification [0012] to [0018]).

1 is a longitudinal cross-sectional view (part of the cross-sectional view is omitted) of an example of a vertical vibration dryer according to the present invention in an assembled state. FIG. 2 is a diagram showing the binary dielectric characteristics of the relative permittivity (ε _r ) and the dielectric loss tangent (tan δ) of various materials, which are used as the selection criteria for the dielectric layer constituent materials in the present invention.

An embodiment of the present invention applied to a vertical vibration dryer will be described below with reference to Figure 1. The present invention is not limited to this embodiment, but can be applied to various aspects within the technical scope of the claims, and can also be applied to horizontal vibration dryers and vibration fluidized beds. Note that the reference numerals in the illustration are basically the same as those in Figure 1 of the prior application.

In this embodiment, a microwave oscillator M is basically attached to a vertical vibration dryer VU.
The vibration dryer VU includes a cylindrical vertical treatment vessel 11 and an oscillator (vibration means) 13 that vibrates the treatment vessel 11 .

Specifically, the processing vessel 11 is supported by a compression coil spring (elastic body) 18 disposed on the stand 17. Here, the compression coil spring 18 may be a leaf spring or an elastic body such as vibration-isolating rubber depending on the output and type of the vibration motor 13.

In the illustrated example, the processing vessel 15 has a central raised portion (navel) at the bottom, forming an annular processing space T, allowing the raw material held in the annular processing space to swirl, and the aforementioned microwave irradiation port is located in a portion of the annular processing space. The central raised portion is supported by a valve body 29 of a vertically movable valve V for product discharge. A product discharge pipe 31 is attached to the downstream valve body of the valve body 29. The vertically movable valve body 30 is driven by an air cylinder 30a. In addition to the microwave irradiation section (irradiation port) R described below, the ceiling wall of the processing vessel 15 is also provided with a dust collection section D on the upper surface of the ceiling, which includes a raw material inlet (not shown), a built-in filter 33, and a steam exhaust port 35. A punched plate 31 is attached to the entrance of the dust collection section D to prevent microwave leakage. Although not shown, the steam exhaust port 35 of the dust collection section D is connected to a suction pipe, which is connected to a suction pump via a steam recovery container or the like.

In the above configuration, in this embodiment, microwaves emitted from the microwave oscillator M are connected to the microwave irradiation unit R of the processing vessel 11, which is an applicator, via a microwave coaxial cable 37, which is a flexible waveguide member. The microwave irradiation unit R is made up of a vacuum seal unit 43 connected to the tip side of the coaxial cable 3737 and an irradiation antenna 45 that outputs microwaves. Although microwave attenuation is greater than that of a waveguide, the coaxial cable 37 is more flexible and has better vibration resistance than a waveguide.

Although some components of the microwave oscillator M are not shown, the oscillator (magnetron) is connected to a power supply control panel E, and a control mechanism such as an isolator is connected to the outlet side of the oscillator via an apparatus waveguide 39. A mode converter 41 is provided at the outlet of the waveguide 39. The mode converter 41 can alternately switch between a coaxial cable mode and a waveguide mode. The base side of the coaxial cable 37 is connected to the converter 41.

The tip of the coaxial cable 37 is a microwave irradiation section R that is composed of a seal section 47 and an antenna section 48 .

Up to this point, the embodiment is substantially the same as the embodiment in the prior application. In the embodiment according to the present invention, at least the portion of the inner surface that comes into contact with the raw material during operation is made of a dielectric layer 15. In the illustrated example, the dielectric layer 15 is formed over the entire height of the inner wall and the entire bottom surface side except for the discharge valve 29. Here, the raw material contact portion of the valve body V may also be covered with a dielectric layer, but if the valve body 29 is made of a ceramic material, the generation of metal wear powder can be prevented.

As described above, the material forming the dielectric layer 15 is a polymeric or ceramic material that satisfies both the relative permittivity ( _εr ) of 10 or less and the loss (tan δ) of 0.08 or less (both at a frequency of 2.45 GHz and 25°C; the same applies below). In the illustrated example, the dielectric layer 15 is a resin layer. As described above, the resin layer is preferably a flammable non-polar thermoplastic resin (e.g., PP). The dielectric layer may be formed from a cartridge container that is detachable from the processing container body. The above-mentioned functions and effects are achieved.

In the above, the processing vessel body is usually made of steel from the viewpoint of strength, so no special electromagnetic shielding is required except for the underside of the valve body. If the valve body is made of a ceramic material, a punching plate is attached to the underside. The valve body may be made of metal, and its upper and peripheral surfaces may be formed with a dielectric layer. Furthermore, as long as strength can be ensured, the processing vessel body may be made of a metal punching plate for electromagnetic wave shielding.

The use of the vertical vibration dryer is basically the same as that of the conventional or prior application (see paragraphs [0029] to [0038] of the specification of the prior application). When the raw material contains inorganic powder and the dielectric layer is formed from a polymer material such as a thermoplastic resin, there is a risk that polymer abrasion powder will be contained in the product after vibration treatment. However, since inorganic powder is usually sintered when being made into a molded product, the polymer abrasion powder will be burned away and will not be a problem.

11 Processing container (main body)
13 Vibration motor (vibration means)
15 Dielectric layer 21 Central protrusion (umbilicus)
35 Steam outlet 37 Coaxial cable (flexible waveguide member)
39 Oscillator (Magnetron)
UV Vertical vibration dryer D Dust collection section M Microwave oscillator E Power supply T Annular processing space R Microwave irradiation section V Valve body

Claims (6)

A vibration treatment device equipped with a vibration applying means for vibrating a treatment container,
A vibration treatment device in which the raw material is a powder or a powder-containing raw material in a slurry or paste form, and the vibration means causes the raw material charged into the treatment vessel to flow upward and downward along the wall of the treatment vessel,
A microwave oscillator is provided, and an output port of the microwave oscillator is connected to the microwave irradiation unit via a coaxial cable;
the treatment vessel is provided with a steam exhaust means and has an electromagnetic shielding structure, and further, at least the raw material contact portion of the inner surface during operation is made of a dielectric layer made of a polymer material and having a thickness of 0.5 to 5 mm;
The polymer material is a polymer material that satisfies both of the following characteristics: a relative dielectric constant (εr) of 10 or less and a loss angle (tanδ) of 0.08 or less (both at a frequency of 2.45 GHz and at 25°C; the same applies hereinafter).
A vibration treatment device characterized by: 2. The vibration treatment apparatus according to claim 1, wherein the treatment vessel further comprises a temperature control jacket. 2. The vibration treatment apparatus according to claim 1, wherein the dielectric layer is formed in a cartridge container that is detachable from the treatment container body. The vibration treatment device according to claim 1, characterized in that the vibration treatment device is a vertical vibration dryer, the treatment container has a central raised portion (navel portion) at the bottom and is provided with an annular treatment space, the raw material held in the annular treatment space is capable of swirling and flowing, and the microwave irradiation section is provided for a part of the annular treatment space. 5. The vibration treatment device according to claim 4, wherein the central raised portion is formed as a vertical valve for opening and closing a product discharge port formed in the center of the bottom of the treatment vessel. A vibration treatment method, characterized in that combustible polymer abrasion powder contained in a product prepared using the vibration treatment device according to claim 1 is burned away.