JP6933933B2 - Heat mixer - Google Patents

Description

The present invention relates to a heating mixer that heats a processed product in a container by irradiating it with microwaves and agitates and mixes the processed product, and more particularly to suppressing microwaves leaking from the container.

Patent Document 1 introduces a heating mixer for drying and mixing and granulating a silt substance having a high water content generated in a dam reservoir or the like, and mixes a processed product with a microwave irradiation means for heating the processed product in a container. It is described that the stirring means is provided. The stirring means includes a rotating shaft provided by inserting the bottom surface of the container, and a blade member attached to the rotating shaft. In such a heating mixer, batch processing (batch processing) is usually performed.
It is described that the treatment time can be shortened by using microwave heating together as compared with the case of treating only with a jacket using a heating medium at 80 ° C.

Patent Document 2 describes an apparatus for desalting in order to reuse mixed waste plastic, and introduces a heating mixer provided with a jacket. Then, it is described that the mixture is kept at a temperature of 250 ° C. or higher for 2 to 3 hours while stirring and mixing in a reducing atmosphere.
In the treatment of the resin accompanied by the reaction, it is considered that the use of a heating mixer is excellent because it is necessary to lengthen the residence time. Then, in addition to the heating by the jacket, it is considered preferable to use the microwave heating together.

However, when high-power microwaves are introduced into a metal container, troubles such as electric discharge and microwave leakage occur.
For example, if two metals are close to each other or if an acute-angled metal piece or the like is present, an electric discharge is generated and the surrounding parts are damaged. In particular, in the input port and discharge port of the processed material provided in the container, the lid of the container, etc., a gap is likely to be generated between the flanges, and discharge and microwave leakage are likely to occur.
Such troubles in the flange portion can be dealt with relatively easily by improving the contact (conductivity) between the flanges.

A more serious problem is leakage in the gap near the shaft seal through which the rotating shaft that agitates the inside of the container penetrates. That is, microwaves leak from the gap between the rotating shaft and the shaft hole.
In particular, when high-speed stirring is performed, it is difficult to improve the conductivity between the rotating shaft and the container, so there is no document suggesting a solution to this problem.

JP-A-2002-346598 Japanese Unexamined Patent Publication No. 2000-178376

An object of the present invention is a heating mixer that heats a processed material in a container by irradiating it with microwaves and agitates and mixes it. It suppresses microwave leakage from the container and causes discharge in the container and its vicinity. The purpose is to provide a heating mixer that does not cause damage to parts. In particular, the purpose is to attenuate and suppress microwaves leaking to the outside through the gap between the rotating shaft and the shaft hole.

The present invention is a heating mixer including a microwave irradiation means for heating a processed product in a container and a stirring means for mixing the processed product, and the stirring means inserts the bottom surface of the container. In a shaft seal box provided below the bottom surface of the shaft seal box provided with a rotating shaft provided and a blade member attached to the rotating shaft, a part of the rotating shaft is covered with a microwave absorbing member. It is a feature.

The blade member may have a choke structure on the surface facing the bottom surface.
Further, the shaft sealing box may be formed with an inner peripheral surface surrounding the rotating shaft, and the inner peripheral surface may have a choke structure.
Further, the shaft sealing means in the shaft sealing box may be configured to be a gas seal.

The heating mixer of the present invention has a structure in which a part of the rotating shaft is covered with a microwave absorbing member, so that the microwave leaked into the gap between the rotating shaft and the shaft hole is greatly attenuated, and the component beyond it is greatly attenuated. It is possible to prevent a discharge that damages the air, and to significantly reduce the microwave leaking to the outside.
Further, it is possible to configure the structure so that the microwave passes through the choke structure before reaching the microwave absorbing member, and it is also possible to attenuate the microwave flowing into the microwave absorbing member in advance.
Therefore, microwave heating and stirring and mixing of the processed product can be performed without any problem.

It is a conceptual diagram around a container which shows an example of the heating mixer of this invention. It is a conceptual diagram which shows an example of the microwave irradiation means. It is a schematic cross-sectional view which shows an example of a stirring means. It is a schematic cross-sectional view and XX arrow view schematic view which shows an example of the choke structure formed on the blade member. It is a schematic cross-sectional view which shows the structure of the microwave absorption member which surrounds a rotating shaft, and a gas seal. It is the schematic which shows an example of the choke structure formed in an annular body.

FIG. 1 is a conceptual diagram showing a schematic configuration around a container 20 in order to show an outline of a heating mixer 10 which is an example of the present invention.
The heating mixer 10 includes a microwave irradiation means 80 for heating the processed material in the container 20, and a stirring means 30 for mixing the processed material.

The container 20 is placed on the gantry 11 integrally with the container holding pedestal 60, and is juxtaposed with the motor 12. The upper part of the container 20 is provided with a supply port 21 for the processed material and a microwave introduction port 23, and the lower part is provided with a discharge port 22 for the processed material.
The heating mixer 10 is configured to perform batch processing, but in the present invention, it may be configured to perform continuous processing.

The microwave irradiation means 80 is a means for supplying microwaves suitable for heating the processed material, and the microwaves propagate through the waveguide 85 and are guided to the heating mixer 10, and are guided from the introduction port 23 to the container 20. It can go inside and heat the processed material.

The stirring means 30 is provided at the lower part in the container 20. Then, the rotational force of the electric motor 12 rotates the stirring means 30 via the transmitting means housed inside the gantry 11 to mix the processed products. It is preferable that the rotation speed is variable.

In addition to heating by microwave irradiation, the heating mixer 10 can also heat the processed material in the container 20 from the jacket, and is provided with an inlet 14 and an outlet 15 for heating oil as a heating medium. There is. Further, a gas seal is used as a shaft sealing means, and a gas inlet 16 is provided.

FIG. 2 shows an example of the microwave irradiation means 80.
The microwave irradiation means 80 includes an oscillator 81 including a magnetron that generates microwaves, an isolator 82 for protecting the oscillator 81 from reflected waves, a tuner 83 that adjusts impedance matching and efficiently transmits power, and a waveguide. The 85 allows microwaves to propagate in the container 20.

FIG. 3 shows the aspect of the stirring means 30 together with the lower part of the container 20, the shaft sealing box 50, and the container holding table 60.
The stirring means 30 includes a rotating shaft 31 provided by inserting the bottom surface 26 of the container 20, and two blade members attached to the rotating shaft 31, that is, a lower blade member 32 and an upper blade member 33.

The container 20 has a cylindrical shape having a vertical axis, and heat treatment and mixing treatment are performed on the processed material put into the container 20.
The peripheral wall of the container 20 is doubly formed by the inner wall 25 and the outer wall (jacket) 27, and the processed product can be heated by flowing a heating medium through a flow path having an annular cross section.

The rotating shaft 31 is attached to the container holding base 60 via a bearing 61. Although only one bearing 61 is shown in FIG. 3, the bearings are actually supported at two places.
Since the rotating shaft 31 is vertically held by the container holding table 60 and the center of the bottom surface 26 of the container 20 is inserted, the stirring means 30 is rotatably positioned at the lower center of the container 20. ..

A shaft sealing box 50 of the rotating shaft 31 is attached to the lower portion of the container 20 to protect the gap between the rotating shaft 31 and the shaft hole. That is, it prevents the processed material in the container 20 from flowing into the gap, and also prevents foreign matter from entering the container 20 through the gap from the outside.
The shaft seal can be a ground seal, but when handling powder, it is preferable to use a gas seal that operates by flowing gas through the gap.
Here, the bottom surface 26 of the container 20 including the upper surface portion of the shaft sealing box 50 will be referred to. It is preferable that the bottom surface 26 does not form a step between the portion of the shaft sealing box 50 and the portion of the container 20.

The heating mixer 10 is provided with three means for suppressing the leakage of microwaves from the gap between the rotating shaft 31 and the shaft hole. The choke structure 70 described with reference to FIG. 4, the higher-order mode attenuation section 73 and the microwave absorbing member 75 described with reference to FIG.

As shown in FIG. 4, the lower blade member 32 is integrally formed by a boss portion 32a through which the rotating shaft 31 is inserted and a pair of blade portions 32b.
The lower surface 36 of the boss portion 32a is a circular surface located horizontally, and is a surface facing the bottom surface 26 of the container 20. Before that, the microwave leaking from the gap between the rotating shaft 31 and the shaft hole travels in the gap between the lower surface 36 of the boss portion 32a and the bottom surface 26 of the container 20 from the outer peripheral side toward the center. become.

A choke structure 70 is formed on the lower surface 36 of the boss portion 32a.
That is, the choke structure 70 is a means formed so that the microwave traveling to leak cancels the reflected wave from the choke groove 71 on the lower surface 36 of the boss portion 32a. Specifically, a choke groove 71 having a groove width B is formed at a position of a distance A from the outer circumference of the boss portion 32a in a circular groove shape at a depth C, and further, a constant width D from here toward the center. Is formed of.
The width D can be formed from the choke groove 71 toward the outside, and the width D can be eliminated. These specific dimensions are determined from the frequency, the size of the boss portion 32a, and the like.

Regarding the choke groove 71 forming the choke structure 70, it is preferable to prevent foreign matter from adhering to the groove, and it is preferable to close the choke groove 71 with an insulator.
As the insulator, PTFE (polytetrafluoroethylene), which is easy to process and has a low relative permittivity, is excellent.

FIG. 5 shows a higher-order mode attenuation section 73 and a microwave absorbing member 75 formed in the shaft seal box 50.
That is, the shaft seal box 50 is formed with an inner peripheral surface 51 surrounding the rotating shaft 31, and a gap y between the rotating shaft 31 and the inner peripheral surface 51 is intentionally formed long to form a higher-order mode damping section. 73 is formed. Here, the gap y is shown larger than it actually is for the sake of clarity.
The microwave leaking here propagates in various modes other than TEM, which is the basic mode of the coaxial line, depending on the diameter of the rotating shaft 31 and the shaft hole. Higher-order modes such as, etc. can be attenuated by the effect of the cutoff of the waveguide.

Further, in the shaft sealing box 50, a part of the rotating shaft 31 is covered with the microwave absorbing member 75.
That is, the rotating shaft 31 is formed so as to penetrate through the microwave absorbing member 75 formed in a cylindrical shape. The gap y between the rotating shaft 31 and the peripheral wall surface of the microwave absorbing member 75 is also shown in the same manner as described above.
With this configuration, it is possible to absorb microwaves passing through the gap y and suppress leakage to the outside. The number of microwave absorbing members 75 may be plurality, and the larger the total volume, the greater the effect of suppressing microwave leakage.
As the microwave absorbing member 75, SiC (silicon carbide) having good absorption efficiency and flame retardancy is excellent.

FIG. 5 also describes the mode of the gas seal. Air is generally used as the gas, but nitrogen gas, argon gas, or the like is used in the treatment requiring an inert atmosphere.
The gas flow path includes a flow path x from the supply port 55 to the rotating shaft 31, a gap y between the rotating shaft 31 and the microwave absorbing member 75, and a gap between the lower surface 36 of the boss portion 32a and the bottom surface 26 of the container 20. It is supplied to the inside of the container 20 via z.

The shaft seal box 50 is provided with an oil seal 52 and a seal ring 53 in order to limit the flow of gas.
The gas supplied into the container 20 is discharged from an exhaust port (not shown), and in the flow path, a perforated plate for preventing leakage of microwaves, a filter for collecting fine powder, and the like are provided. It is provided.

Next, FIG. 6 shows a case where the choke structure 70 shown in FIG. 5 and the higher-order mode attenuation section 73 are interchanged and arranged.
That is, the lower surface 36 of the boss portion 32a forms a higher-order mode damping section 73 at a portion located at the gap z with the bottom surface 26 of the container 20, and the inner peripheral surface 51 surrounding the rotation shaft 31 of the shaft sealing box 50 is formed. The choke structure 70 is formed.

A test for dissolving the resin mixture was conducted using the heating mixer 10 of the present invention.
The capacity of the container 20 was about 20 liters, and a heat medium of 120 ° C. was supplied to the jacket. The rotation speed of the stirring means 30 was 420 rotations per minute, and air was used for the gas seal.

As a treated product, 2000 g of a mixture consisting of 1100 g of SIS and 900 g of liquid paraffin was used.
Here, SIS is a styrene-isoprene-styrene copolymer.

With respect to the microwave output of 3.0 KW used, the maximum amount of microwave leakage from the periphery of the rotating shaft 31 was ^{about 0.4 mW / cm 2} , and it was confirmed that there was no problem in safety.
In addition, no damage to the parts due to the discharge was observed.

The dissolution test is performed on the assumption that batch processing is continuously performed, and for the second and subsequent batch processing in which the inside of the container 20 is already hot, from the input of the processed material to the product temperature reaching 140 ° C. The time was measured.
Shows three results of the test conducted by changing the heating method (1) When microwave heating and jacket heating are used together …… 6.5 minutes (2) When only microwave heating is used …… 16 minutes (3) Jacket In case of heating only …… 37 minutes

As a result of the above, in the heating method using microwaves, unlike the conventional heating by heat transfer, rapid heating is possible because the processed material is heated from the inside, and it is economically heated by using jacket heating together. It was confirmed that the mixing process is possible.
Therefore, it was confirmed that the heating mixer of the present invention is very effective in reusing waste plastics and the like.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the design change to the extent that the gist of the present invention is not deviated is the present invention. include.
For example, various modes can be considered for the stirring means 30 shown in FIG.

10: Heating mixer 20: Container 26: Bottom surface 30: Stirring means 31: Rotating shaft 32: Lower blade member 50: Shaft sealing box 51: Inner peripheral surface 70: Chalk structure 75: Microwave absorbing member 80: Microwave irradiation means

Claims (3)

A heating mixer including a microwave irradiation means for heating a processed material in a container and a stirring means for mixing the processed material.
The stirring means includes a rotating shaft provided by inserting the bottom surface of the container, and a blade member attached to the rotating shaft.
In the shaft seal box provided below the bottom surface, a part of the rotating shaft is covered with a microwave absorbing member .
A gas flow path from the inside of the shaft seal box to the inside of the container is formed, the shaft seal means in the shaft seal box is performed by a gas seal, and a groove-shaped choke structure is formed in the flow passage. A characteristic heating mixer. In the heating mixer according to claim 1,
The blade member includes a boss portion through which the rotating shaft is inserted.
The flow passage is formed in a gap between the lower surface of the boss portion and the bottom surface, and the choke structure is formed on the lower surface of the boss portion.
A heating mixer characterized by that. In the heating mixer according to claim 1,
The shaft seal box is formed with an inner peripheral surface that surrounds the rotating shaft.
The flow passage is formed between the rotation axis and the inner peripheral surface, and the choke structure is formed on the inner peripheral surface.
A heating mixer characterized by that.

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