JP2893478B2 - Powder drying equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for drying a granular material. More specifically, the present invention relates to an apparatus for drying a granular material such as a synthetic resin material using a microwave, and particularly to a granular material amount detecting apparatus for adjusting the residence time of the granular material in a treatment tank.

[Prior art and its problems] Powders such as synthetic resin materials are generally water-absorbing and must be dehydrated and dried to the extent that they do not hinder the molding process during molding.

Most conventional drying devices use hot air,
The powder of the synthetic resin material was placed in a drying tank and dried with hot air to make the water content less than an allowable amount.

However, synthetic resins have a problem with heat resistance, and when a dry material is exposed to hot air at a certain temperature or higher for a long time, the surfaces are softened and fused to each other and cannot be dried uniformly, or the surface is discolored. Since it cannot be used as a molding material, it must be dried with hot air at a relatively low temperature, and there is a problem that it takes a long time to dry.

Therefore, the present applicant has focused on microwaves that can heat powders and granules from the inside, and installed a microwave device in the drying treatment tank. By using microwave heating, powders and particles that can be dried more quickly than conventional hot-air dryers (Japanese Patent Application Laid-Open No. 64-67305), and has proposed a drying / crystallization apparatus for further improving the quality of other drying apparatuses or polyester resin (PET) while drying while proceeding with crystallization. (JP-A-1-163006, JP-A-163007, JP-A-1-1630)
No. 08, No. 1-301310, No. 2-13782).

That is, in Japanese Patent Application Laid-Open No. 1-301310, a material inlet and a material outlet are provided for the purpose of preventing the powder to be dried placed in the heat treatment tank from causing uneven heating due to irregular reflection of microwaves. Then, in a horizontally long processing tank provided with a microwave device and a dehumidifying air supply device, a plurality of disk-shaped partitions are attached to a drive shaft installed in a longitudinal direction, and a partition space is formed between each adjacent partition. This device proposes a device provided with stirring blades for transferring the particles in each isolation space to the isolation space on the material outlet side while stirring the partition walls.The device is driven as charging and discharging of the particles to be dried is performed. The granular material is sequentially transferred to the isolated space adjacent to the material outlet side by the stirring blade rotating with the shaft, and is subjected to microwave irradiation while being retained and mixed there, so that uniform heating is performed. is there.

In Japanese Patent Application Laid-Open No. Hei 2-13782, heating by microwaves is too efficient, and the time required for vaporizing moisture in the granules becomes longer than the heating time (microwave irradiation time), so that the temperature of the granules increases. In order to suppress, irradiation by the microwave device must be performed intermittently, and in view of the problem that drying that makes full use of the performance of the microwave device cannot be performed as a result, it is connected to the heat treatment tank outlet of the above device, The present invention provides an apparatus having a drying tank provided with a dehumidifying air blow-in port. It can be dried quickly.

Here, in order to perform uniform drying in the granular material drying apparatus having the above-mentioned horizontally long heat treatment tank, it is necessary to maintain the amount of the granular material supplied to the heat treatment tank at an appropriate constant level. is necessary.

For this purpose, a method is adopted in which a level meter for detecting the level of the amount of the granular material in the processing tank is installed, and the opening and closing of the material inlet portion is controlled in conjunction with the level meter.

Conventionally, as such a level meter, (1) a torque method,
(2) Ultrasonic method, (3) Capacitance method, (4) Contact method, and (5) Photoelectric method, all of which have problems in adopting a powder drying apparatus using microwaves. is there.

That is, in the torque method, the capacitance of the material is not stable due to a rapid temperature change in the processing tank, so that accurate operation cannot be performed. In addition, when the level surface is moving without standing still, malfunction occurs and the stirring is performed. It is easy to pick up noise from the blades.In the ultrasonic method, malfunction occurs due to the air current in the processing tank.In the capacitance method, the level meter itself contains a dielectric substance and the temperature rises due to microwaves, leading to malfunction and Microwaves penetrate into the meter and leak from there, affecting the human body or causing radio interference.In the contact method, the material is mixed too much in the treatment tank, so it is easy to pick up noise from the stirring blades and contact points. Since the number of ON-OFF times increases, the life is shortened. Even if the photoelectric system is directly installed in the processing tank, the reliability is lacking because the material is flowing and the amount of dust is large.

Accordingly, an object of the present invention is to provide a device for drying a granular material provided with a microwave device (in this specification including the claims, the term drying device is used to refer to both the drying device and the dry crystallization device. )) And developed a powder mass detector (level meter) that can be used stably and supply the material so that the residence time of the powder is always constant, and dry the powder that can be uniformly heated It is to provide a device.

Means for Solving the Problems The present inventors attach a member capable of reliably capturing the flow of a material conveyed laterally in a horizontally-long heat treatment tank when the flow exceeds a predetermined level. By detecting the movement of the member with an optical sensor (photoelectric switch), the above problem was successfully solved, and the present invention was developed.

That is, the present invention provides a horizontally-long heat treatment tank 1 having a material inlet 8, a material outlet 9, and a dehumidified air supply port 10, and applies microwaves to the powdery material supplied to the horizontally long heat treatment tank 1. Microwave device 20 for irradiation, dehumidified air supply device 50,
While mixing the granules, the material inlet 8 to the material outlet 9
A granular material having a stirring device for continuously transporting the granular material, a granular material amount detecting device 30 for detecting the amount of the granular material in the treatment tank, and a material supply control means interlocked with the granular material amount detecting device In the drying device, the granular material amount detecting device 30 has a closed structure having an opening 33 communicating with the processing tank below and preventing microwaves from leaking to the outside, and opposing positions above both side walls 31a and 31b. One of the tube members 32a and 32b is provided with a photoelectric switch mounted on one side and a light receiver 37 on the other side, and is turned around an axis 34 parallel to the light transmission direction of the photoelectric switch diagonally below the tube member. A particulate material flow capturing member 35 loosely fitted so as to be movable, wherein the particulate material flow capturing member 35 is suspended from a shaft 34, and an upper portion 35a thereof does not block light from the photoelectric switch and a lower portion thereof. 35b extends to the permissible level of the particles to be dried in the processing tank 1, and the lower portion 35b extends to the permissible level. Top 35 in conjunction when rotating the shaft 34 as the fulcrum when capturing the granular material flow beyond the Le
a is to provide a powder and granule drying apparatus characterized in that it blocks the light of the photoelectric switch.

[Configuration of the Invention] Hereinafter, the configuration of the present invention will be described based on examples.

FIG. 1 (a) is a side sectional view of the heat treatment tank 1 in the granular material drying apparatus according to the present invention, and FIG.
FIG. 1 (c) is a sectional view taken along the line BB. The heat treatment tank 1 is constituted by an upper wall 11, a lower wall 12, both side walls 13a and 13b, and both side walls 14a and 14b so as to be horizontally elongated and hermetically sealed so that microwaves do not leak. The upper wall 11 is provided with a material inlet 8 at one end, a plurality of microwave devices 20 having a waveguide 16, and a device 30 for detecting the amount of dry powder and granular material.
The lower wall 12 is shown in FIGS. 1 (b) and 1 (c).
As shown in the figure, the lower wall 12 and the side walls 13a have a semi-circular cross-section.
13b, the cross section of the processing tank 1 has a U-shape,
At the end of the lower wall 12 opposite to the material inlet 8 in the longitudinal direction, there is provided a material outlet 9 provided with a rotary feeder 15 for continuously discharging a predetermined amount of the granular material. The dehumidified air supply port 10 is mounted above the rotary feeder 15 of the section 9. A drive shaft 4 to which a plurality of stirring members 6 are attached is installed slightly below the center of both end walls 14a and 14b across both walls 14a and 14b, and a drive such as a motor attached to one end wall 14b is driven. The drive shaft 4 is rotated by connecting to the device 40.

As shown in the side sectional view and the CC sectional view thereof in FIGS. 2 (a) and 2 (b), the granular material amount detecting device 30 has an opening 33 having a lower part communicating with the heat treatment tank. It has a hermetically sealed structure made of a metallic material that does not leak microwaves to the outside.

Tube members 32a, 32b are provided at opposing positions above both side walls 31a, 31b.
Are fixed, one of which is the transmitter 36 and the other is the receiver
An output of an amplifier unit (not shown) of this photoelectric switch is connected to material supply control means (not shown).

On both walls 31a, 31b, a shaft 34 is suspended obliquely below the pipe members 32a, 32b, and a powder flow capturing member 35 is loosely fitted on the shaft 34, with the shaft 34 serving as a fulcrum. The granular material flow capturing member is configured to be rotatable.

The upper portion 35a of the particulate material flow catching member 35 extends to a height at which light from the photoelectric switch passes when the particle flow capturing member 35 is naturally suspended from the axis 34, but the optical axis (light transmission direction) is the axis 34. , The light from the projector is not blocked.

On the other hand, the lower portion 35b of the particulate material flow capturing member extends to an allowable level of the particulate material to be dried in the processing tank 1, and when the particulate material to be dried is transported beyond the allowable level, the powder material flow is reduced. The lower portion 35b of the capturing member captures the flow of the granular material and rotates about the shaft 34, so that the upper portion 35a of the capturing member comes to a position where the light from the photoelectric switch is cut off.

The material supply is controlled by controlling the opening and closing mechanism of the rotary feeder at the material inlet 8 and the rotary feeder at the material outlet 9 based on the output information of the amplifier unit of the photoelectric switch.

The diameter and length of the tube member of the powder and particle amount detection device are selected and designed so that microwaves do not leak.

The particulate material flow capturing member 35 is made of a metal material, and the lower portion 35b
Can reliably capture the flow of the granular material approaching the set allowable amount, and at this time, any shape may be used as long as the upper portion 35a blocks the light of the photoelectric switch.

The granule drying device of the present invention is configured as described above, and while the agitating member 6 of the drive shaft 4 is rotated by the driving device 40, the granules are removed from the processing tank 1 by the rotary feeder 15 of the material outlet 9. The powder is discharged quantitatively, and the granules are sequentially charged from the material inlet 8 to maintain the granules remaining in the processing tank 1 at a predetermined amount. Irradiation is performed on the powder and granules staying in the processing tank 1 through the waveguide 16 to heat the powder and granules.

The moisture of the powder is evaporated by heating by microwaves, and the material inlet provided at the end of the upper wall 11 together with the dehumidified air supplied from the dehumidified air supply device 50 through the dehumidified air supply port 10. The air is circulated to the dehumidifying air supply device through an exhaust port near the unit 8.

During the heating operation, the light-receiving unit 37 of the powder-particle detection device constantly receives light from the projector 36 of the photoelectric switch 32.

The granular material flow capturing member 35 of the granular material detection device is located at a lower portion thereof.
35b reaches near the height of the shaft of the stirring member, that is, reaches a position slightly lower than the upper limit of the allowable amount of the granular material in the processing tank, and the amount of the granular material in the heat treatment tank is appropriate. At this time, the lower portion 35b of the particulate material flow capturing member is hung directly below the shaft 34, does not contact the granular material in the heat treatment tank, and the upper portion 35a does not block light from the photoelectric switch.

In this state (the state in which the light receiver detects light), the opening / closing means of the material inlet 8 and the rotary feeder 15 of the material outlet are maintained in a steady state of material supply.

On the other hand, when the amount of the granular material in the heat treatment tank approaches the allowable amount, the lower end 35b of the capturing member comes into contact with the material transferred to the outlet side by the stirring device, and the upper portion 35a is on the opposite side in the transfer direction. , The light of the photoelectric switch is cut off, and the light receiver 37 does not detect the light (see 35 shown by a broken line in FIG. 2B). In this state, the opening / closing means of the material inlet 8 and the rotary feeder 15 at the material outlet operate to stop the supply of the material.

If the drying process is continued in this state, the powder and granules are removed from the material outlet 9.
The particles in the processing tank are unilaterally discharged and the particles in the processing tank are reduced, so that the lower portion 35b of the capturing member does not come into contact with the particles, the light receiver detects the light again, and the supply of the material from the material inlet 8 is started. You.

In the above description, the stirrer and the dehumidifying air supply device are not described in detail because they do not directly relate to the features of the present invention. Various agitation devices that can be used in a horizontal drying device, such as those proposed in No. 301310, can be applied.

Also, as for the dehumidifying air supply device, as described in JP-A-2-13782 described in the section of the prior art, a drying tank having a dehumidifying air intake port is connected to an outlet of the heat treatment tank, and a drying tank is provided. Air may be introduced into the heat treatment tank and released to the atmosphere via a material inlet or from a separately provided exhaust port, or may be circulated to a dehumidified air supply device.

[Effects of the Invention] In the granular material drying apparatus of the present invention, a granular material detecting device that operates stably and reliably is attached, and the supply of material is controlled in conjunction with the granular material amount detecting device. An appropriate amount of the granular material is held in the heat treatment tank, and uneven heating of the powder due to irregular reflection of microwaves and variation in the residence time of the granular material in the treatment tank is eliminated, and uniform drying of the granular material is performed as a whole. .

[Brief description of the drawings]

FIG. 1 (a) is a schematic side sectional view of one example of the apparatus for drying a granular material according to the present invention, and FIG. 1 (b) is AA in FIG. 1 (a).
FIG. 1 (c) is a cross-sectional view taken along the line BB of FIG. 1 (a), and FIG. 2 (a) is a side cross-sectional view of an example of the granular material detection device according to the present invention, FIG. FIG. 2B is a sectional view taken along the line CC of FIG. 2A. Reference numerals in the drawing: 1 ... heat treatment tank; 4 ... drive shaft; 6 ... stirring member; 8 ... material inlet; 9 ... material outlet; 10 ... dehumidifying air supply port; 11 ... upper wall; 12 …… Bottom wall; 13a, 13b …… Side wall; 14a, 14b …… End wall; 15…
... Rotary feeder; 16 ... Waveguide; 20 ... Microwave device; 30 ... Powder detector; 31a, 31b, 31c, 31d ... Detector side wall; 32a, 32b ... Tube member; 33 ... … Opening; 34 ……
Shaft; 35 ...... powder / particle flow capturing member; 35a ... upper capturing member; 35b
…… the lower part of the capturing member; 36 …… the projector; 37 …… the receiver; 40 ……
Driving device; 50 ... dehumidifying air supply device.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-13782 (JP, A) JP-A-55-99573 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F26B 3/347 F26B 23/08 F26B 25/04 F26B 17/20 F26B 21/12

Claims (1)

(57) [Claims] 1. A horizontally elongated heat treatment tank 1 having a material inlet 8, a material outlet 9, and a dehumidified air supply port 10, and microwaves are supplied to the powder supplied to the horizontally elongated heat treatment tank 1. A microwave device 20 for irradiation, a dehumidified air supply device 50, a stirring device for continuously transferring the powder and granules from the material inlet 8 to the material outlet 9 while mixing the powder and granules, A granular material amount detecting device 30 for detecting an amount, and a granular material drying device including a material supply control unit interlocked with the granular material amount detecting device, wherein the granular material amount detecting device 30 The tube member 3 has an opening 33 communicating with the processing tank and has a hermetically sealed structure in which microwaves do not leak to the outside, and is opposed to the upper side wall 31a, 31b.
2a and 32b are provided with a photoelectric switch having a light emitter 36 mounted on one side and a light receiver 37 on the other side, and are rotated on a shaft 34 parallel to the light transmission direction of the photoelectric switch diagonally below the tube member, with the shaft 34 as a fulcrum. A particulate material flow capturing member 35 loosely fitted to obtain the particulate material flow capturing member 35, and in a state where the particulate material flow capturing member 35 is suspended from the shaft 34, its upper portion 35a does not block light from the photoelectric switch, and its lower portion 35b has The upper portion 35a, which extends to the permissible level of the particles to be dried in the processing tank 1, and which is linked to the axis 34 as a fulcrum when the lower portion 35b captures the powder flow exceeding the permissible level, transmits the light of the photoelectric switch. An apparatus for drying a granular material, characterized in that the drying apparatus shuts off the powder.