JPH0729844B2 - Microwave heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a molded body extruded in a predetermined shape as a continuous body, and in a short time, cracks, twists, warps, bends,
The present invention relates to a microwave heating device capable of rapidly reducing water content without explosion.

[Conventional technology]

Generally, as a device for drying an extruded body of clay containing 22 to 18% by weight of water, an electric heater, a hot air atmosphere furnace, a far infrared heater, a microwave heater, etc. are known.
Then, the extruded body was dried by the above-mentioned apparatus by either a badge method or an oven continuous method.

[Problems to be solved by the invention]

However, the electric heater and the hot air atmosphere furnace have a drawback that it takes several hours to several days to dry because the object to be heated is heated from the surface. In addition, a microwave heater can reduce moisture in a short time by heating an object to be heated such as clay, but water vapor evaporated during heating stays in the space to be heated and condenses on the inner wall of the space to be heated and the surface of the object to be heated. It has a drawback that water adheres to it and causes cracks, warpage, twisting, and explosion, and that the drying efficiency is lowered. Further, in the microwave heater, a conveyor belt is used to convey the material to be heated. For this reason, when an extruded product made of clay that shrinks more than 10% in volume during extrusion and during drying is heated, the effect is particularly pronounced in the case of an extruded product that is a continuous body. There was a disadvantage to concentrate on. In addition, microwaves have high radio wave density on both sides in the longitudinal direction of the continuum and are easily heated, causing uneven heating, and the back surface of the object to be heated is not directly irradiated with microwaves, so that the microwave is gradually radiated from the inside. There was a disadvantage that cracks, twists, warps and explosions were caused due to the escape route of water vapor at that time.

[Means for solving problems]

In order to eliminate such drawbacks, the present invention uses a fli roller capable of absorbing the shrinkage of the volume for transporting the object to be heated, and the side edges in the longitudinal direction of the elongated body are covered with U-shaped blocking plates. Is electrically high in density, and microwaves are radiated from the back surface of the free roller to the back surface of the object to be heated to average the heating and to cover the steam in the heated space. Air is fed to the object to be heated so as to be discharged from the inlet / outlet of the object to remove the disadvantages caused by dew condensation, and cracks, warps, twists, and explosions in the object to be heated can be reduced rapidly. The microwave heating device is proposed.

〔Example〕

An embodiment of the microwave heating device according to the present invention will be described in detail below with reference to the drawings. 1 and 2 (a) and (b) are explanatory views showing a typical example of the above apparatus. In the figure, reference numeral 1 is a waveguide for guiding a microwave oscillated from a microwave oscillator (not shown) to a required position. Reference numeral 2 is a reflecting plate for changing the direction of the microwave A and dispersing it in the heated space 3. Reference numeral 4 is for stirring the microwave A reflected by the rotary blades,
It is dispersed evenly in the heated space 3. Reference numeral 5 denotes a roller conveyer, as shown in FIGS. 2 (a) and 2 (b), in which mainly the microwave A, air B, etc. are uniformly radiated or blown onto the extruded product C, and the extruded product C is dried. When doing 1
Since the whole is shrunk to some extent, the extruded product C can be conveyed while absorbing this. As a specific example thereof, as shown in FIGS. 3 (a) and 3 (b), a pipe-shaped fli roller 7 made of a fixed core rod 6 and Teflon, a core rod support 8 as shown in FIG. It is composed of a plate 9. To further explain, in FIG. 3 (a), the width of the fli roller 7 is divided into three, and the resistance when passing through the extrusion molded body C is further reduced, and FIG. 3 (b) shows the fli roller 7 constituted by one. In addition, the core rod support 8 is provided with a through hole 8a so that the microwave A is also irradiated from the back surface of the extrusion molded body C. When the extruded body C is a long body, the shielding plate 9 suppresses high density on both side edges of the upper part and the longitudinal direction in a radio wave manner, and irradiates the weak heating part and weak heating part. It is useful for uniform heating by strengthening. 10 is an inlet, 11 is an outlet, which feeds the extruded product C to the heated space 3 via the roller conveyor 5 , and sends it to the next step from the outlet 11 so that the microwave A does not leak to the outside and It serves as an outlet for discharging the water vapor B'generated during heating to the outside. A cover 12 surrounds the heated space 3 and blocks the microwave A from leaking to the outside. Reference numeral 13 denotes a through hole which is a supply port or a suction port for air B or the like, and air (dry air, not shown) such as a compressor or a ring blower (not shown).
It is connected to a prime mover for an air cycle that can blow hot air or air) or suck air. In particular, the heated space 3
The air B or the like is supplied to the outside to release a large amount of water vapor generated during heating from the heating atmosphere to the outside, to eliminate evaporation of dew condensation water and water vapor on the exposed surface of the object to be heated, and to easily evaporate dew condensation. This is because it is possible to remove adverse effects (strain, warp, twist, crack, explosion) caused by the above and to eliminate dew condensation water adhering to the inner wall of the cover body 12. In the microwave heating apparatus according to the present invention, the length of the heated space 3 varies depending on the thickness and width of the extrusion-molded body C and the extrusion speed of the extrusion-molding machine D. For example, 2 to 100-2000 mm / min. It is around 10m.

Next, the operation will be described.

First, a clay consisting of Shigaraki clay, chamotte, a water reducing agent and water is prepared as a raw material. The weight% is, for example, Shigaraki clay 61.5%, chamotte 18%, water reducing agent 0.5% (trade name Cell Flow: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and water 20% by extrusion molding machine (MP-100 type manufactured by Miyazaki Iron Works). It was kneaded in. Also, the extrusion molding machine D has an extrusion capacity of 100 to 150 / hr.
Model name MV-FM-A-1 (Miyazaki Tekko Co., Ltd.)
Extruded at 200 mm / min of ~ 2000 mm / min. Further, the transfer mechanism E has a free roller and a drive belt conveyor arranged in this order, and the microwave oscillator has a frequency of 2450.
MHz, output 5kw, length of heated space 3 is 3m, air B
Is sent to the heated space 3 from one wall surface of the cover body 12, and the steam B'generated during heating is discharged to the outside through the inlets and outlets 10 and 11 to reduce the steam pressure in the heated space 3. The roller conveyer 5 is a free roller 7 made of a Teflon pipe, which is configured to prevent the generation of dew condensation water on the object to be heated and the inner wall of the cover body 12. In addition, the microwave heating device uses 18% (% by weight) of water content of the extruded product C.
It is assumed that the water content is evaporated to 12% (weight%), and the remaining water content is evaporated by a far infrared heater (not shown) to reduce the water content to 1% or less. Therefore, from Extruder D
An extrusion-molded body C having a cross section shown in (a) of FIGS. (A) to (j) is continuously extruded, and is fed to a microwave heating device through a transfer mechanism E. In the microwave heating device, the extrusion-molded body C was irradiated with the microwave A evenly, and the steam B'generated during heating was blown away so that it hardly remained in the heated space 3 and no dew condensation was observed. Of course, extruded product C
There were no cracks, warpages, or explosions. The water content was reduced to 12% in about 10 minutes, and even if the space between the extrusion-molded bodies C that had passed through the microwave heating device from the exit of the extruder D was a continuous body, the extruder D was soft. No change was observed in the extruded product extruded from the outlet of, and it was conveyed smoothly at the extrusion speed. As a comparative example, a roller conveyor 5 was used as a belt conveyor, and a microwave heating device without a through hole 13 for supplying air B or the like to the cover body 12, a core rod support 8, and a shielding plate 9 was used, and the same as above. When the material is extruded in the same manner, the surface of the extruded product C and the space 3 to be heated are filled with water vapor, and dew adheres to the extruded product C and the like. Penetration is small, the side edges in the longitudinal direction of the extruded product C become electrically high density, the middle in the width direction becomes a weak heating part and becomes non-uniform heating, cracks, warps and twists are observed, and immediately after extrusion In the extruded product, a shrinkage part was observed due to the influence of the velocity deviation due to the volume shrinkage that occurs when the water content is reduced.

What has been described above is only one example of the microwave heating apparatus according to the present invention. As shown by the alternate long and short dash line in FIG. 1, air and warm air are passed through the through holes from the rear surface of the roller conveyor 5 to the heated space 3. It is also possible to use it together with 13 or supply instead of it.

〔The invention's effect〕

As described above, according to the microwave heating device of the present invention, 1/3 to 2/3 of the total water content of water is 10 to 10 while the extruded body made of the raw material whose main material is clay remains as a continuous body. It has the feature that it can be reduced in a short time of about 30 minutes without cracking, warping, twisting or explosion. In addition, the heating is performed by irradiating the extruded body with microwaves from the front and back surfaces of the extruded body so as to heat the extruded body evenly, and covering both side edges in the longitudinal direction where the electrical density becomes high, and the weak heating part It has the characteristic that the waves are concentrated. Furthermore, the volume of the extrusion molded product extruded from the extrusion molding machine on the roller conveyor shrinks about 10% when dried, but the effect is absorbed and the extruded product does not act on the soft extruded product immediately after being extruded and bends smoothly. There is a feature that can be transported without.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a microwave heating apparatus, and FIGS. 2 (a) and 2 (b) are perspective views of a section to be heated along an E-line and a heated space in which a roller conveyor is mounted. 3 (a), (b), and FIG. 4 are explanatory views showing a roller conveyor which is one of the essential parts of the present invention, and FIG. 5 (a).
(J) is explanatory drawing which shows the cross section of an extrusion molded body. 1 ... Waveguide, 3 ... Heated space, 5 ... Roller conveyor, 13 ... Through hole, A ... Microwave, B ... Air, etc.
C ... Extruded body.

Claims (1)

[Claims] 1. A microwave heating apparatus for feeding an extruded body mainly composed of clay extruded from an extruder through a transfer mechanism and drying the extruded body in an oven continuous system,
The guide and transfer of the extruded product to be heated are formed by a roller conveyor composed of a flea roller having a structure that does not overheat and spark, and microwaves pass through the vertical surface of the core rod supporter that supports the core rod of the roller conveyor. A large number of holes are provided, and a microwave blocking plate is formed in a U-shaped cross section so as to cover the front and back sides of both side edges of the extrusion molded body at both end portions of the roller conveyor through which the extrusion molded body passes. A microwave heating device characterized by being attached.