JP3028239B2 - Heating and drying treatment equipment - Google Patents

Description

The present invention relates to a drying position of a granular material. More specifically, the present invention relates to an apparatus for heating and drying powders of synthetic resins and other general organic substances (sugar, grains such as rice, synthetic seasonings, etc.) using microwave heating.

[Prior art and its problems] Most of the conventional drying apparatuses for drying granules made of organic matter containing water or a low-boiling solvent use hot air. The water content was less than the desired amount.

However, organic substances generally have a problem in heat resistance,
If the dried material is exposed to hot air at a certain temperature for a long period of time, the surface will melt or soften and fuse with each other, making it impossible to dry uniformly, or discoloring the surface and deteriorating the commercial value. Since it cannot be used as a molding material, it has to be dried with hot air of relatively low temperature, and there is a problem that it takes a long time to dry.

Therefore, the present applicant pays particular attention to microwaves that can be heated from the inside of granular materials such as synthetic resin, and attaches a microwave device to the drying tank, and the microwave heating makes it faster than conventional hot air drying devices. Application for a drying device for powders and granules that can be dried quickly (JP-A-64-67305)
No. 1), and a drying and crystallizing apparatus in which drying is performed while further crystallization is performed with another drying apparatus or an amorphous polyester resin (PET), etc. (JP-A-1-163006, No. 1-163007, No. 1-163008,
Nos. 1-301310 and 2-13782).

In these devices, while the powder supplied from the material inlet of the processing tank and transferred to the outlet is uniformly stirred and dehumidified air is passed, an external microwave oscillator (magnetron) is used.
Then, the microwave is oscillated, the microwave is guided into the treatment tank through the waveguide, and the material to be dried is irradiated with the microwave, and the powder is heated from the inside for a certain period of time to perform drying.

As an example of a drying apparatus developed by the present applicant, Japanese Patent Laid-Open No.
13782 is shown.

That is, this device is shown in FIG.
As shown in FIG. 1 (b), which is a sectional view taken along line AA of the heat treatment tank of FIG. 1 (a), a horizontally long heat treatment tank 1 having a material inlet portion 4 and a material outlet portion 5; Microwaves are supplied from a drying tank 9 connected to the section 5 via a rotary feeder 10 and an opening 16 defined by a fluorine resin plate 16a which is guided by the waveguide 3 and transmits microwaves at the top of the heat treatment tank. A stirring member 7 having a microwave device 2 for irradiation and a dehumidifying air supply device 8, and a stirring member 7 having a plurality of disc members 7 a and stirring blades 7 b attached to a plurality of disk members 7 a is provided in the longitudinal direction of the horizontally long processing tank 1. The dehumidifying air supply device 8 is connected to an air blowing port 12 to the drying tank 9, and air is connected from the drying tank 9 to a connecting pipe.
15. A dehumidified air supply device 8 provided through a punching plate 11a that does not allow dry material provided in the lower opening portion 11 of the processing tank 1 but allows air to pass therethrough, an outlet near the material supply port 4, and a return pipe 19
Is circulated to In this apparatus, the drying ability of a drying tank 9 provided separately and connected to the processing tank 1 is controlled so that the microwave device 2 of the heating processing tank 1 can be continuously operated to dry the powder and granules continuously and quickly. It is made possible.

In such an apparatus, a microwave oscillated from a microwave apparatus is reflected by a wall of a metal processing tank, a metal stirring member installed in the processing tank, and a part of the microwave passes through a waveguide. Return to the microwave device.

If a large amount of microwaves is reflected on such a microwave device, the microwave device is damaged and its life is significantly shortened. Conventionally, as shown in FIG. 2, a power for measuring a traveling wave (incident power) 23 and a reflected wave (reflected power) 24 in a path (waveguide) 22 leading to a microwave device 20 and a heat treatment tank 21. A monitor 25 is installed to monitor the matching condition between the microwave oscillator (magnetron) 20 and the load, and a separately installed matching device 26 is adjusted so that the reflected power is as small as possible, and the incident power is set to nearly 100%. The isolator 27 that separates the microwave in the waveguide into the incident wave and the reflected wave is attached, and only the reflected light is absorbed by the water load to prevent damage to the magnetron due to the excessive reflected wave and protect it. . In such a conventional device, the reflected wave is 30
It reached ~ 40% or more, and the power efficiency was extremely poor.

Accordingly, an object of the present invention is to provide an apparatus for heating and drying an organic substance using microwaves, which has less reflected waves, has a longer life of a microwave oscillator, and has higher power efficiency.

[Means for Solving the Problems] The present inventors have studied the microwave heating apparatus for many years and found that the ratio of the reflected wave to the traveling wave (incident wave) was determined by the output of the microwave oscillator and the volume of the heating tank. The authors acknowledged that there was a correlation between the ratio of the reflected wave and the result of further research. By setting this ratio to a specific relationship, the ratio of reflected waves was significantly lower than that of the conventional device (10% or less). (Up to about 4%), and completed the present invention.

That is, the present invention provides a horizontally elongated processing tank 1 having a U-shaped cross-sectional shape with a semicircular bottom, and an opening 16 made of a microwave transmitting material provided on the upper part of the processing tank 1.
And a microwave generating device 2 connected through a microwave oven. The semi-circular portion of the processing tank 1 has a radius r of 1/2 of the width m of the processing tank. And the output W of the microwave generator 2 is represented by {(2/1) πr ² + m × (hr)} × L (where h is the height including the bottom portion of the processing tank, and L is the processing tank. With respect to the processing tank internal volume V defined by the length in the extension direction of V), by setting V [cm ³ ] / W [watt] ≧ 8, the reflected wave / incident wave power ratio is set to 10% or less. A microwave heating and drying apparatus is provided.

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

1 (a) and 1 (b), a power monitor is installed in the waveguide 3 from the microwave oscillator 2 to the heat treatment tank 1 and a pellet of polyethylene terephthalate as a heating material is placed in a predetermined position. Microwaves were transmitted while changing the output of the microwave oscillator and the volume of the heat treatment tank after charging in a quantity, and traveling waves and reflected waves were measured by a power monitor.

(1) Four magnetrons each having an output of 1.3 kW were used, and each having a width m, a height h, and a lower radius m / 2 as shown in FIGS. 3 (a) and 3 (b) through a waveguide. In a semicircular, horizontally long heat treatment tank of length l, m = 20 cm, h = 23 cm,
Microwaves were radiated from the upper four places of the heat treatment tank at l = 80.6 cm, and the reflected waves were measured by a power monitor.

The volume (V) of this device is [(π / 4) × (20) ² × (1/2) + 20 × (23−10)] × 80.6 = 33610 cm ³ , while the reflected power (reflected wave) is total It was 2.1KW. Therefore, V / W = 33610/5200 = 6.46 (cm ³ / watt), and the ratio of the reflected wave is 2.1 / (1.3 × 4) × 100 = 40.4%.

(2) As a heat treatment tank, FIGS. 3 (a) and 3 (b)
The reflected wave was measured in the same manner as in (1) except that m = 24 cm, h = 34.9 cm, and l = 80.6 cm were used, and the reflected power (reflected wave) was 360 watts in total.

From the above results, the volume (V) of this apparatus is [(π / 4) × (24) ² × (1/2) + 24 × (34.9−12)] × 80.6 = 62707 cm ³ , and V / W = 62707 /5200=12.1 (cm ³ / watt), and the ratio of the reflected wave is 360 / (1.3 × 4) × 100 = 6.9%
Becomes

(3) One magnetron with an output of 1.3 kW is used, and through a waveguide, m = 17.5c in FIGS. 3 (a) and 3 (b).
When microwaves were irradiated from the upper part of the heat treatment tank of m, h = 21 cm and l = 40 cm, and reflected waves were measured by a power monitor, the reflected power was 128 watts.

The volume (V) of this device is [(π / 4) × (17.5) ² × (1/2) + 17.5 × (21-8.
8)] × 40 = 13360 cm ³ , therefore V / W = 13360/1300 = 10.3 (cm ³ / watt), and the reflection ratio is 128/1300 x 100 = 9.8%.

(4) Two magnetrons each having an output of 1.3 kW were used, and through the waveguide, m = 20 cm in FIGS. 3 (a) and 3 (b).
When microwaves were irradiated from the top of the heat treatment tank with h = 27 cm and l = 80.6 cm, and reflected waves were measured by a power monitor, the reflected power was 2600 watts.

The volume (V) of this device is [(π / 4) × (20.0) ² × (1/2) + 20.0 × (27-1
0)] × 80.6 = 40058 cm ³ Therefore, V / W = 40058/2600 = 15.4 (cm ³ / watt), and the reflection ratio is 125/2600 × 100 = 4.8%.

FIG. 4 shows the above results, plotting the ratio of the reflected wave on the vertical axis and V / W on the horizontal axis.

Therefore, the value of V / W is more than 8 cm ³ / watt, preferably 10 cm
It is understood that the ratio of the reflected wave can be reduced by setting the value to ³ / watt or more.

The larger the V / W is, the smaller the reflected wave can be. However, if this value is unnecessarily large, the heat treatment tank becomes large and the cost increases, so that there is a limit naturally. Considering heating efficiency and equipment cost, V /
The value of W is preferably about 10 to 50.

[Effects of the Invention] The present invention relates to a drying apparatus for organic powders heated by microwaves, wherein the output of a microwave oscillator is W (watts) and the volume of a heat treatment apparatus is V (cm ³ ). V / W
Is set to 8 cm ³ / watt or more.

Since the ratio of the reflected wave to the traveling wave (incident wave) is much lower than that of the conventional device, the device of the present invention has a long microwave oscillator life and is excellent in power efficiency.

[Brief description of the drawings]

FIG. 1 (a) is a schematic cross-sectional view of an example of a drying apparatus for organic powders, FIG. 1 (b) is a cross-sectional view taken along the line AA of FIG. 1 (a), and FIG. FIG. 3A and FIG. 3B are dimensional diagrams of devices for measuring a reflected wave, respectively. FIG. 4 is a schematic diagram illustrating a measurement system of a reflected wave. It is the graph which plotted the relation between the ratio of the volume (V) of the heat treatment device to the output (W) of the oscillator, and the ratio of the reflected wave. Symbols in the figure: 1 ... heat treatment tank; 2 ... microwave device; 3 ... waveguide; 4
…… Material inlet; 5 …… Material outlet; 6 …… Drive shaft; 7a ……
Disc material; 7b Stirring blade; 7 Stirring member; 8 Dehumidifying air supply device; 9 Drying tank; 10, 18 Rotary feeder; 11 Opening; 11a Punching plate; 12… air inlet; 13… blower tube; 14… connecting tube; 15… air connecting tube; 16
a: Fluorine resin plate; 16b: Opening; 17: Drive unit; 19
…… Return tube; 20 …… Microwave device; 21 …… Treatment tank; 22…
... waveguide; 23 ... traveling wave; 24 ... reflected wave; 25 ... power monitor; 26 ... matching device; 27 ... isolator.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-13782 (JP, A) JP-A-1-303038 (JP, A) JP-A-62-254803 (JP, A) 107193 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F26B 23/08

Claims (3)

(57) [Claims] 1. A horizontally long processing tank (1) having a U-shaped cross section with a semicircular bottom, and an opening (16) provided on the processing tank (1) and made of a microwave transmitting material. A microwave heating and drying apparatus having a microwave generator (2) connected via a waveguide (3), wherein the heating and drying processing is performed by using a microwave, wherein a radius r of a semicircular portion of the processing tank (1) is r. Is 1/2 of the width m of the processing tank, and the output W of the microwave generator (2) is
Is defined as {(2/1) πr ² + m × (hr)} × L (where h is the height including the bottom portion of the processing tank, and L is the length in the extension direction of the processing tank). A microwave heating / drying apparatus characterized in that the ratio of reflected wave / incident wave power is set to 10% or less by setting V [cm ³ ] / W [watt] ≧ 8 with respect to the processing tank inner volume V. 2. A granule having a drying tank (9) connected to an outlet end of a granular material of the horizontally long processing tank (1), and a blowing port (12) in the drying tank (9). A dehumidifying air supply device (8) having an inlet at a material inlet end, and circulating the dry air in the horizontal processing tank (1) in a direction opposite to a direction in which the granular material is transferred, The microwave heating and drying apparatus according to claim 1, wherein a drying treatment with dry air is performed simultaneously with the microwave heating. 3. The microwave according to claim 1, wherein the output W of the microwave generator (2) satisfies 10 ≦ V [cm ³ ] / W [watt] ≦ 50 with respect to the processing tank volume V. Heat drying treatment equipment.