JPH04174287A - Heating drying processing device - Google Patents

Abstract

PURPOSE:To obtain an excellent device, long in the life of whose microwave oscillator and high in the power efficiency thereof, by a method wherein the value of V/W is set so as to be higher than 8cm<3>/watt when the output of the microwave oscillator is W watt and the volume of the heating processing device is Vcm<3>. CONSTITUTION:In the heating drying processing device of granular bodies, which utilizes microwave, the value of V/W is set so as to be 8cm<3>/watt when the output of the microwave oscillator 2 is W watt and the volume of the heating processing device is Vcm<3>. The rate of reflecting waves is reduced by setting the value of V/W so as to be 8cm<3>/watt or more or preferably 10cm<3>/ watt or more in such a manner. The rate of the reflecting waves becomes smaller as the value of V/W is set higher, however, when this value is set too much higher, the size of the heating processing tank 1 is increased and the cost of the same becomes high whereby there is a limit naturally. The value of V/W is preferably the degree of 10-50 practically when the heating efficiency and the cost of the device are considered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drying device for powder and granular materials. More specifically, the present invention relates to a device for heating and drying powdered materials of synthetic resins and other general organic substances (sugar, grains such as rice, synthetic seasonings, etc.) using microwave heating.

[Prior art and its problems] Conventionally, most drying devices for powder and granules made of organic substances containing water or low-boiling point solvents use hot air. The water content was to be less than the desired amount.

However, organic materials generally have problems with heat resistance, and if dry materials are exposed to hot air above a certain temperature for a long time, the surface may melt or soften and fuse together, making it impossible to dry uniformly or causing deterioration such as discoloration of the surface. In addition, synthetic resins may become unusable as molding materials, so they must be dried with relatively low-temperature hot air, which poses a problem in that drying takes a long time.

Therefore, the present applicant focused on microwaves that can heat powders and granules such as synthetic resins from the inside, and installed a microwave device in the drying treatment tank, and by microwave heating, compared to conventional hot air drying devices. Japanese Patent Application Laid-Open No. 64-67305 concerning a drying device for powder and granular materials that can be quickly dried.
(No. 1), and subsequently worked on improving other drying equipment and proposed a drying/crystallization equipment that dries amorphous polyester resin (PET) while proceeding with crystallization (
Unexamined Japanese Patent Publication No. 1999-iesooe, 1. -163007,
1-183008, 1-301310, 2-
No. 13782).

In these devices, dehumidified air is passed through while uniformly stirring the powder and granules supplied from the material inlet of the processing tank and transferred to the outlet, while microwaves are oscillated from an external microwave oscillator (magnetron). Drying is carried out by irradiating the material to be dried by guiding microwaves into the processing tank through a waveguide and irradiating the material to be dried for a certain period of time to heat the powder from within.

As an example of a drying device developed by the applicant, JP-A-2-1
3782 is shown.

That is, as shown in FIG. 1(a) as a schematic side sectional view and FIG. 1(b) as a sectional view taken along line A-A of the heat treatment tank in FIG. A horizontally elongated heat treatment tank 1 having a material outlet part 5, a drying tank 9 connected to the outlet part 5 via a rotary feeder 10, and a microwave transmitted through the upper part of the heat treatment tank guided by a waveguide 3. A microwave device 2 that irradiates microwaves from an opening 16 partitioned by a fluorocarbon resin plate 16a, etc., and a dehumidified air supply device 8 are provided. Stirring member 7 with stirring blades 7b attached to a plurality of disc members 7a
is installed, and the dehumidified air supply device 8 is connected to the drying tank 9.
A punching plate 11a that is connected to the air inlet 12 and that allows air to flow from the drying tank 9 to the connecting pipe 15 and the lower opening 11 of the processing tank 1, which does not allow the drying material to pass through but allows the air to pass through.
1 is circulated to the dehumidified air supply device 8 through an outlet near the material supply port 4 and a return pipe 19. In this device, the drying capacity of the drying tank 9, which is connected to the processing tank 1 and provided separately, can be continuously operated by the microwave device 2 of the heating processing tank 1, so that powder and granules can be dried continuously and quickly. It has been made possible.

In such devices, the microwaves emitted from the microwave device are reflected by the walls of the metal processing tank, the metal stirring member installed inside the processing tank, and some of them pass through the waveguide. Return to the microwave device.

If a large amount of microwaves are reflected by such a microwave device, it will be damaged and its lifespan will be significantly shortened. Therefore, conventionally, as shown in FIG.
A power monitor 25 that measures a traveling wave (incident power) 23 and a reflected wave (reflected power) 24 is installed at 26 is adjusted so that the reflected power is as small as possible so that nearly 100% of the incident power is absorbed by the material, and an isolator 27 is installed that separates the microwave in the waveguide into incident waves and reflected waves. The magnetron is protected by being absorbed by the water load to prevent damage to the magnetron due to excessive reflected waves. In such conventional devices, the reflected waves account for 30 to 40% or more of the traveling waves, resulting in extremely poor power efficiency.

Therefore, an object of the present invention is to provide an apparatus for heating and drying organic powder using microwaves, which has few reflected waves, has a long lifespan of the microwave oscillator, and is highly power efficient.

[Means for Solving the Problems] Based on long-standing studies on microwave heat treatment equipment, the present inventors found that the ratio of reflected waves to traveling waves (incident waves) is determined by the output of the microwave oscillator and the volume of the heat treatment tank. Recognizing that there is a correlation between the ratio of 4%) and completed the present invention.

That is, in the present invention, in an apparatus for heating and drying powder or granular materials using microwaves, when the output of the microwave oscillator is W (watt) and the volume V of the heating apparatus is (cm2), the value of V/W is The present invention provides an apparatus for heating and drying powder and granular material, characterized in that the drying temperature is set to 8CIII3/watt or more.

[Structure of the invention] Hereinafter, the configuration of the present invention will be explained based on examples.

In the apparatus configured as shown in FIGS. 1(a) and 1(b), a power monitor is installed in the waveguide 3 leading from the microwave oscillator 2 to the heat treatment tank 1, and pellets of polyethylene terephthalate, which is the heating material, are Microwaves were transmitted by changing the output of the microwave oscillator and the volume of the heat treatment tank, and the traveling waves and reflected waves were measured using a power monitor.

(1) Output, using 4 S KW magnetrons,
Figure 3(a) and Figure 3(b) through the waveguide, respectively.
As shown in the figure, in an oblong heat treatment tank with a semicircular shape of width m, height h, lower radius m/2, and length g, m = 20c.
Microwaves were irradiated from four locations at the top of the heat treatment tank with m, h = 23 cm (1 = 80.6 cm), and reflected waves were measured using a power monitor.

The volume (V) of this device is [(π/4) x (20) 2x (1/2) + 20
X (23-10) ) X80.6=33610 c
m”, on the other hand, the total reflected power (reflected wave) is 2.IK
It was W. Therefore, V/W=3361015200=6.46 (Cm3/
Watt), and the proportion of reflected waves is 2.1 / (1,3X
4) Xl,0O=40.4%.

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

From the above results, the volume (V) of this device is [(π/4)
X (24) 2X (1/2)+24 X (34,
9-12) ]X80.6=62707cm3, V/
W=6270715200=12. L (Cm”/Watt), and the proportion of reflected waves is 360/(1,3X
4) X100 = 6.9%.

(3) Use one 3 KW Macnetron for output,
Through the waveguide, m=
Microwave was irradiated from the top of the heat treatment tank at 17.5 cm, h = 21 cm, (1 = 4 Q cm), and the reflected waves were measured using a power monitor, and the reflected power was 128 watts.

The volume (V) of this device is [(π/4) X (17,5) 2X (1/2)
+17.5X (21-8,8) ) X 40 = 1
3360 cm", therefore, V/W=13360/L300=10.3 (cm"
/ Walla)) Te, the ratio of reflected waves is 128 / 1
300x100=9.8%.

(4) Using two magnetrons with an output of 1.3 KW,
rn through the waveguide in Figures 3(a) and 3(b).
= 20cm, h = 27cm, 47 = 80.
When microwaves were irradiated from the top of the 6cm heat treatment tank and the reflected waves were measured using a power monitor, the reflected power was 2.
It was 600 watts.

The volume (V) of this device is [(π/4) X (20,0) ” X (1/2)
120, OX (27-10) ]X80.6=40
058cm”, therefore V/W=40058/2600=15.4
(c+n3/Watt), and the proportion of reflected waves is 125
/2600X to.

=4.8%.

FIG. 4 depicts the above results with the ratio of reflected waves on the vertical axis and V/W on the horizontal axis.

Therefore, it can be seen that the ratio of reflected waves can be reduced by setting the value of V/W to 8 cm 3 /W or more, preferably 10 cm 3 /W or more.

Incidentally, the larger the V/W is, the fewer the reflected waves can be, but if this value is increased unnecessarily, the heat treatment tank will become larger and the cost will increase, so there is a limit. From a practical point of view, considering heating efficiency and equipment cost, V/
The value of W is preferably about 1O=50.

[Effects of the Invention] The present invention provides an apparatus for drying organic powder and granular material heated by microwaves, in which the pressure of the microwave oscillator is set to W (watts),
When the volume of the heat treatment equipment is V (Cm3), V/
The present invention provides a device in which the value of W is set to 8CI113/W or more.

Since the device of the present invention has a much lower ratio of reflected waves to traveling waves (incident waves) than conventional devices, it is an excellent device with a long microwave oscillator life and high power efficiency.

[Brief explanation of drawings]

FIG. 1(a) is a schematic cross-sectional view of an example of a drying apparatus for organic powder and granular materials, FIG. 1(b) is a cross-sectional view taken along line A-A in FIG. 1(a), and FIG. 2 is a traveling wave FIG. 3(a) and FIG. 3(b) are dimensional diagrams of the equipment used to measure reflected waves, and FIG. The volume of the heat treatment equipment (V) with respect to the output (W) of the oscillator
) and the ratio of reflected waves. Symbols in the figure: 1... Heat treatment tank; 2... Microwave device; 3
... Waveguide; 4... Material inlet part; 5... Material outlet part; 6... Drive shaft; 7a... Disk material, 7
b... Stirring blade; 7... Stirring member; 8... Dehumidified air supply device; 9... Drying tank; 10, 18... Rotary feeder; 11... Opening; 11a.
...Punching plate; 12...Air inlet; 13.
... Blow pipe; 14... Connecting pipe; 15... Air connecting pipe; 16a... Fluorine resin plate; 16b... Opening; 17... Drive device; 19... Return tube; 20
...Microwave device; 21...Processing tank; 22...
・Waveguide; 23... Traveling wave; 24... Reflected wave;
25... Power monitor; 26... Matching box; 27
···isolator. Patent applicant Kawata Co., Ltd. Patent attorney □ Kunihisa Oya

Claims (1)

[Claims] 1) In a heating drying processing apparatus for powder or granular materials using microwaves, when the output of the microwave oscillator is W (watt) and the volume V of the heating processing apparatus is (cm^3), V An apparatus for heating and drying powder or granular material, characterized in that the value of /W is set to 8 cm^3/W or more. 2) The heat drying processing apparatus according to claim 1, wherein the V/W value is set to 10 cm^3/Watt or more. 3) The heat drying treatment apparatus according to claim 1, wherein the V/W value is set to 10 to 50 cm^3/Watt.