JPH03207987A - Microwave dryer - Google Patents

Abstract

PURPOSE:To suppress the abrasion and damage of a temp. detection means by arranging a buffer body in the vicinity of the means protruding into a drying chamber and detecting the drying temp. of a granular and powdery substance to be dried on the side to which the substance to be dried goes by stirring. CONSTITUTION:A temp. sensor 17 has structure wherein a thermistor is built in a protective pipe and horizontally protrudes into a drying chamber and detects the drying temp. of a substance 5 to be dried in this state. A hard buffer plate 17a made of ceramics or metal is arranged in the vicinity of the temp. sensor 17 on the side to which the substance 5 to dried goes by stirring and integrally has an inclined slide plate 17b on the side of the temp. sensor 17. The substance 5 to be dried is stirred by a stirrer 15 and has considerable speed but rapidly becomes slow by the action of the buffer plate 17a when strikes against the temp. sensor 17 and the temp. sensor 17 is hardly abraded and damaged.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a microwave drying device.

(b) Conventional Technology In the microwave drying apparatus shown in Japanese Patent Application No. 1-47803, while stirring the granular or powdery material to be dried in the drying chamber, a temperature sensor protruding into the drying chamber is used to dry the material to be dried. The drying temperature is detected and the magnetron is driven and controlled based on the detected temperature to perform microwave drying.

By the way, when the temperature sensor detects the temperature of the agitated material to be dried, the material to be dried frequently collides with the temperature sensor at a considerable speed. will wear out and eventually become damaged. In particular, when the material to be dried is hard such as glass-containing resin pellets, the abrasion damage becomes significant.

Note that the glass-containing resin pellets are shaped after being melted, and if the resin pellets are dried prior to such melting and shaping, the subsequent shaping will be better.

(c) Problems to be Solved by the Invention The present invention seeks to provide a microwave drying apparatus in which wear and tear of a drying temperature detection means for detecting the drying temperature of the material to be dried in a drying chamber is suppressed. .

(2) Means for Solving the Problems The microwave drying apparatus of the present invention includes a drying chamber into which a granular or powdery dried material is supplied, and a microwave for microwave drying the dried material in the drying chamber. a microwave supply means for supplying waves; a stirring means for stirring the material to be dried within the drying chamber; a drying temperature detection means protruding into the drying chamber for detecting the drying temperature of the material to be dried; and the drying temperature. It consists of a buffer body disposed in the vicinity of the detection means and on the side toward which the material to be dried 5 is agitated.

(e) Operation The drying temperature detection means for detecting the drying temperature of the material to be dried in the drying chamber is protected by a buffer body on the side toward which the material to be dried is moved by stirring. That is, the speed of the object to be dried hitting the drying temperature detecting means is slowed down by the action of the buffer, and wear and tear on the drying temperature detecting means is suppressed.

(Heno Embodiment FIG. 1 shows the structure of a microwave drying apparatus according to an embodiment of the present invention, which consists of a drying apparatus main body 1 and its peripheral mechanisms.

The main part of the drying device T*1 is an upper lid 2 that can be opened and closed.
A circular drying chamber 3 is provided. A supply pipe 4 is connected to the upper left part of the drying chamber, and the tip of the supply pipe reaches into a storage tank 6 in which granular or powdery material 5 to be dried is stored.

The storage tank is located below the drying chamber 3. Examples of the material to be dried 5 include glass-containing resin pellets, rice, and pharmaceutical powder. ! I resin pellets are shaped after being melted, and if the resin pellets are dried prior to such melting and shaping, subsequent shaping can be done well.

In this example, glass-containing resin pellets are the material to be dried.

A suction hopper 7 is connected to the center of the upper lid 2 of the drying chamber 3 via an integral oval-shaped microwave shielding pipe 7a. The suction hopper 7 consists of a suction pump main body 7b and a hopper top cover 7c which is detachably disposed on the main body. Then, the filter wire mesh 8a and the filter paper 8 are sandwiched between the suction hopper main body 7b and the Honopa top lid 7C.
are removably arranged. These filter wire meshes 8a
The filter paper 8 has a mensch smaller than the material diameter of the material to be dried 5, and the filter paper 8 has a filter wire mesh 8a.
The mesh is smaller.

A poppet valve 9 is provided in the upper lid 7C of the hopper 7 above the filter wire mesh 8a and the filter paper 8. And, in the upper part of the pobet valve 9,
A suction blower 11 is connected to the suction hopper 7 via a suction pipe IO. In this case, if the suction blower 11 is driven with the boppet valve 9 being driven open,
The suction action of the suction blower 11 extends to the suction pipe 10, suction hopper 7, and microwave shielding pipe 4, and the dried vIJ5 in the storage tank 6 is suctioned and passes through the supply pipe 4 to the drying chamber 3. When the material to be dried 5 reaches the drying chamber 3, it falls and accumulates inside the drying chamber due to its own weight.

Here, some of the objects 5 to be dried do not fall into the drying chamber 3 and are then sucked into the suction hopper 7, but such objects 5 are transported from this point forward by the filter wire mesh 8a and the filter paper 8. Therefore, the material to be dried 5 is prevented from being undesirably sucked toward the suction blower 11.

In the drying chamber 3, there is a magnetron 12 inside.
Microwaves are supplied from the dryer via a waveguide 13, and a stirring body 15 that is driven by a motor 14 and stirs the material to be dried 5 is provided on the bottom wall.

A level sensor 16 for detecting whether a predetermined amount of the material to be dried 5 has accumulated in the drying chamber 3 and a drying temperature detecting means, that is, a temperature sensor 17 are arranged on the side wall.

The temperature sensor 17 has a structure in which a thermistor is built in a protection tube, and as shown in FIGS. 2 and 3, it projects horizontally into the drying chamber 3, and in this state, the drying material 5 Detects the drying temperature. Then, the temperature sensor 1
A hard buffer plate 17a made of ceramics or metal is arranged near the drying material 7 and on the side toward which the dried material 5 is directed by stirring. The buffer plate 17a integrally has an inclined sliding plate 17b on the temperature sensor 17 side. In this case, the material to be dried 5 is stirred by the agitator 15 and has a considerable speed, but when it hits the temperature sensor 17, it is rapidly slowed down by the action of the buffer plate 17a, and the temperature sensor l7 is worn out. Not easy to damage.

A compressor 19 is connected to the left bottom portion of the drying chamber 3 via an intake valve 18, and an exhaust valve 20 is provided on the upper lid 2 of the drying chamber 3. The driving of the compressor 19 and the opening of the intake valve 18 and the exhaust valve 20 are performed when the material to be dried 5 is dried by microwaves, etc., and the water vapor generated during drying is transferred from the compressor 1.9 together with air to the exhaust valve. 20 and is discharged to the outside.

Further, a discharge valve 21 is provided at the bottom right of the drying chamber 3, and the discharge valve is opened when the dried material 5 is discharged after drying. The dried material 5 discharged upon opening of the discharge valve 21 falls through the discharge pipe 22 into the preliminary chamber 23 below and accumulates therein. A heat-retaining heater 24 is arranged on the lower inclined wall of the preliminary chamber, and the upper half of the preliminary chamber 23
A level sensor 26 having a rotating body 25 is provided. Such a level sensor 26 normally rotates the rotating body 25, and even if a small predetermined amount of the dried material 5 accumulates in the preliminary chamber 23 and the rotating body 25 is attempted to be rotated, the dried material 5 does not become a load. When the rotating body 25 cannot be rotated satisfactorily, a predetermined signal is output to detect that a small predetermined amount of the material to be dried 5 has accumulated.

The lower part of the preliminary chamber 23 is connected to another suction hopper 27 located higher than the preliminary chamber 23 through a conveying pipe 28. Such a suction hopper 27 also has the above-mentioned suction hopper 7.
Similarly, a filter wire mesh 29a and filter paper 29 having a mesh smaller than the material diameter of the material to be dried 5 are arranged, and a bovet valve 30 is provided above the filter paper. The suction blower l1 is also connected to the suction hopper 27 via the suction pipe 31 above the pobet valve 30.

In this case, with the bovet valve 30 open, the blower 1
1, the intake action of the blower 711 causes the intake pipe 3 1 . The material to be dried 5 accumulated in the preliminary chamber 23 reaches the suction hopper 27 via the UEt pulling hopper 27 . When the material to be dried 5 reaches the suction hopper 27, it falls into the hopper due to its own weight.

In the suction hopper 27, a heat insulating heater 32 is disposed on the lower inclined wall, an on-off valve 33 is provided at the lower end, and upper and lower limit level sensors 34 are provided at the upper and lower ends.
, 35 are arranged.

When the on-off valve 33 is closed, the suction action moves and the material to be dried 5 falls into the suction hopper 27, and the material to be dried 5 accumulates in the suction hopper 27. On the other hand, when the on-off valve 33 is opened, this The dried material 5 thus accumulated falls downward and reaches the next processing section, where the dried material 5, that is, the resin pellet, is melted or shaped.

Figure 4 shows the circuit of the microwave drying device, and the main control section is a part number LC-65PG23 manufactured by Sanyo Electric Co., Ltd.
A microcomputer 36 is provided, and the computer receives operation information from an operation section 37 disposed on the front side of the drying apparatus main body 1, temperature information from the temperature sensor 17, and various level sensors 16, 26. , 34, 35
Based on the information etc. from
, discharge valve 2l, heat retention heaters 24, 32, suction blower 1l
, the poppet valves 9 and 30, and the on-off valve 33.

FIG. 3 shows a flowchart of the operation program installed in the microcomputer 36, and the operation of the microwave drying apparatus will be explained below along the same chart.

After the power is turned on, after the S1 step, normally S2, S3, S
Steps 3a, S4, and S5 are executed cyclically. S1
In the step, an initial setting operation is performed. That is, all writable areas in the microcomputer 36 are cleared, and the magnetron 12, motor 14,
The compressor 19, the heat retaining heaters 24, 32, and the suction blower 11 are placed in a stopped state, and the intake valve 18,
The exhaust valve 20, the exhaust valve 2l, the poppet valves 9 and 30, and the on-off valve 33 are each placed in a closed position. In step S2, the operation information from the operation unit 37 is input, in step S3, it is determined by the lower limit level sensor 35 whether or not the material to be dried 5 has accumulated in the suction hopper 27, and in step S3a, the above Based on the detection by the level sensor 26, it is determined whether or not a predetermined amount of the material to be dried 5 is accumulated in the preliminary chamber 23. In the S4 step, microcomputer 3
The presence or absence of cents in the start flag within 6 is checked, and S5
In step S2, it is determined whether the start key is currently being operated by the operation unit 37 based on the input information in step S2.

When the object 5 to be dried, which is a resin pellet, is to be melted and shaped, if the object 5 to be dried is to be pre-dried so that the shape can be properly formed, first, the operation section 37 is used to perform the operations 20 to 20. 60
The desired drying time and drying temperature are respectively set within the range of 10 minutes and within the range of 70 to 170° C. using the keys, and the continuous switch 38 is turned on. These operation information are input in step S2. After that, when the start key is operated on the operation unit 37, such information is similarly input in step S2, an affirmative determination is made in step S5, the start flag is subsequently set in step S6, and the above-mentioned information is entered in step S7. Drive control of the heat retention heaters 24 and 32 is started. That is, the heat-retaining heaters 24 and 32 are intermittently driven at a desired ratio so that the interiors of the preliminary chamber 23 and suction hopper 27 are maintained approximately at the set drying temperatures, and therefore the interiors of the preliminary chamber 23 and suction hopper 27 are maintained at approximately the set drying temperature. It is kept warm at the above temperature.

Next, steps S8, S9, and SIO are sequentially executed. In step S8, it is checked whether the transport flag in the microcomputer 36 is set (in this case, it is checked that it is not set). In step S9, an operation of supplying the material to be dried 5 to the drying chamber 3 is executed. That is, the vacuum valve 9 is opened, the suction blower 11 is driven, the material to be dried 5 is supplied from the storage tank 6 into the drying chamber 3 by the suction action of the suction blower 11, and the motor 14 is driven. The stirring body 15 rotates, and the upper surface of the material to be dried 5 supplied into the drying chamber 3 is aligned with a smooth horizontal surface. 5
In step 10, it is determined by the detection by the level sensor 16 whether a predetermined amount of the material to be dried 5 has accumulated in the drying chamber 3 (in this case, it is determined that the predetermined amount has not accumulated).

After that, S2, S3, S3aSS4, Sll, S8~5
Each of the 10 steps is executed cyclically. At this time, in the Sll step, it is checked whether the supply end flag in the microcomputer 36 is set. When a predetermined amount of the material to be dried 5 accumulates in the drying chamber 3 and this is determined in the SIO step, steps S12 and 513 are then executed. 5
In step 12, the operation of supplying the material to be dried 5 to the drying chamber 3 executed in step S9 is completed. In step S13, the supply end flag is set.

After that, S2, S3, S3aSS4, S11, S14~
Each step of S17 is executed cyclically.

At this time, in step S14, the microcomputer 36
It is checked whether the drying end flag is set in S15.
A drying operation is performed in the step. That is, the magnetron 12 is intermittently driven depending on whether or not the temperature of the object 5 to be dried detected by the temperature sensor 17 has reached the set drying temperature, and the object 5 to be dried is maintained at the drying temperature and subjected to microwave drying. , and the motor l4 is re-driven and the stirring body 1
5 is rotated to agitate the material 5 to be dried evenly, and at the same time, the compressor 19 is driven and the intake valve 1
8. The exhaust valve 20 is opened and the water vapor generated from the material to be dried 5 is discharged to the outside. Further, in step 515, along with such drying operation, measurement of the elapsed drying time is started.

In step S16, it is determined whether the elapsed drying time has reached the set drying time, and in step 517, it is checked whether the conveyance flag is set, as in step S8.

Therefore, when the elapsed drying time reaches the set drying time, 5
After 16 steps, steps S18 and S19 are executed. In step 518, the drying operation performed in step 515 and the measurement of elapsed drying time are terminated, and the measured time is reset. In step S19, the drying end flag is set.

And S17, S2, S3, S3a. S4, Sll,
After passing through step S14, S20, S21, S22, S
Steps 23 and S24 are sequentially executed. In step S20, the presence or absence of cents in the discharge flag in the microcomputer 36 is checked. In step 521, based on the detection by the level sensor 26, it is determined whether or not a small amount of the material to be dried 5 has already accumulated in the preliminary chamber 23. In step S22, if a heat-retaining operation (described later) is being performed in the drying chamber 3, this is terminated and the discharge flag is set. Step S23 is executed when the dried material 5 is allowed to be newly discharged from the drying chamber 3 to the preliminary chamber 23 because the material 5 to be dried is not accumulated in the preliminary chamber 23 in step S21. Therefore, in step s23, an operation of discharging the dried material 5 from the drying chamber 3 to the preliminary chamber 23 is executed. That is, the discharge valve 21 is opened and the motor l4 is continuously driven to rotate the stirring body 15.
As the material rotates, the material 5 to be dried near the stirring body 15 is pushed to the surrounding area, and the material 5 to be dried is discharged from the discharge valve 21 to the discharge pipe 22.
It falls and is discharged into the preliminary chamber 23 through the. The dried material 5 discharged in this way does not naturally cool down because the preliminary chamber 23 has been kept warm since step S7, and the dried material 5 absorbs moisture again due to natural cooling. is prevented. Furthermore, in the above step S23, counting of the elapsed time of such discharge is started. In step S24, it is determined whether the elapsed discharge time has reached a predetermined discharge time (this is sufficient time to discharge all of the predetermined amount of material to be dried 5 stored in the drying chamber 3). It is determined whether or not.

After that, S2, S3, S3a. S4, Sll, 514,
Each step of S20, S23, S24, and S17 is executed in circulation, and when a small predetermined amount of OI5 to be dried accumulates in the preparatory chamber 23 due to the above-mentioned discharge, in such circulation, 83a
Steps s25, S26, S27, and S28 are sequentially executed. In step S25, a conveyance flag is set, and in step 526, if the drying material supply operation is being executed in step s9, the operation is stopped. In step S27, an operation is carried out to transport the dried material 5 from the preliminary chamber 23, which is kept warm, to the suction hopper 27. That is, the bobbet valve 3o is opened and the suction blower 11 is driven, and the suction hopper 27 is removed from the preliminary chamber 23 by the suction action of the suction blower 11.
The material to be dried 5 is transported to. The dried material 5 transported in this manner is not naturally cooled because the suction hopper 27 is kept warm from step s7, and the dried material 5 is prevented from absorbing moisture again. In step 528, it is determined by the detection of the upper limit level sensor 34 whether or not the dried material 5 has accumulated in the suction hopper 27 up to the position of the sensor (in this case, it is determined that no).

After that, S4, S11, 514, s20. S23, 52
4,517, S27, 528 (7) Each step is executed in circulation, and during this period, the discharge operation to the preliminary chamber 23 and the transport operation of the suction hopper 27l\ are processed in parallel, and the dried material discharged to the preliminary chamber 23 is processed in parallel. 5 is immediately conveyed to the suction hopper 27.

Then, when the elapsed discharge time reaches a predetermined discharge time (all the materials to be dried 5 are discharged from the drying chamber 3 to the preliminary chamber 23), steps 529, S30, and S31 are sequentially executed. Ru.

In step S29, the ejection operation and elapsed elapsed time measurement performed in step S23 are completed, and the measured time is reset. In step 530, all of the above-mentioned supply end flag, drying end flag, and discharge flag are reset. In step S31, it is determined whether or not the continuous switch 38 is turned on using the operation unit 37.

In this case, the continuous switch 38 is in the on state, and after passing through step S17, S4, s11. S8, S27
, S28 are executed cyclically. Then, the material to be dried 5 in the preliminary chamber 23 is transported to the suction hopper 2.
When the dried material 5 accumulates up to the position of the upper limit level sensor 34 at step 7, steps S28 to S32 and S33 are executed. In step S32, the transport operation executed in step S27 is stopped, and in step S33, the transport flag is reset.

Therefore, the dried material 5 accumulated in the suction hopper 27 in this way
is melted and shaped in the next processing section, which is
This process is executed when an external command signal P for instructing melting and forming is given to the microcomputer 36 in a state where the dried material 5 is accumulated in the suction hopper 27 up to the position of the upper limit level sensor 34 . That is, at this time, the on-off valve 33 is opened by the microcomputer 36, and the material to be dried 5 is discharged from the suction chamber 27 to the next stage processing section. The opening/closing valve 33 is closed again when all of the dried material 5 in the suction hopper 27 is discharged. Then, the discharged material to be dried 5 is melted and shaped in the next processing section, and in this case, the resin pellets, that is, the material to be dried 5 are dried in advance, so that the material to be dried is well shaped.

Here, if the processing capacity of the next-stage processing section for melting and shaping is slow, the drying material supply operation to the conveying operation is repeated, so that the drying material is stored in the suction hopper 27 and the preparatory chamber 23. 5 remains accumulated. Therefore, when the drying material 5 is accumulated in the pre-chamber 23 and the drying material 5 is to be taken out from the drying chamber 3, this is determined in step 521. It is determined that a predetermined amount or more of the material 5 has accumulated and that the material 5 to be dried is not allowed to be newly discharged from the drying chamber 3 to the preliminary chamber 23. Then, the dried material 5 remains in the drying chamber 3 even after drying.
left inside. If such leaving is simply carried out, drying v
Even if lJ5 is dried, it will naturally cool down and absorb moisture again, but in this embodiment, in order to prevent this, S34
Step is executed. That is, in step S34, the same control as the drying operation in step S15 is performed, and the material to be dried 5 is kept warm at the set drying temperature using microwaves.
Therefore, the material to be dried 5 is prevented from absorbing moisture again in the drying chamber 3.

The series of operations described above is ended by turning off the continuous switch 38. That is, when the S3l step is executed in such an off state, the S35 step is then executed, the start flag is reset, and the drive of each of the heat retention heaters 24 and 32 is stopped. After that, S2, S3,
Steps S3a, S4, and S3 are executed cyclically.

(G) Effects of the Invention According to the present invention, it is possible to suppress wear and tear of the drying temperature detection means for detecting the drying temperature of the material to be dried in the drying chamber, and to provide a practical microwave drying apparatus.

[Brief explanation of drawings]

The drawings relate to a microwave drying device according to an embodiment of the present invention.
The figure is a front sectional view, Fig. 2 is a plan sectional view of the main part, Fig. 3 is a sectional view taken along the line III-III in Fig. 2, and Fig. 4 is a circuit diagram.
FIG. 5 is a flowchart of the operating program of the microcomputer. 3... Drying chamber, l 2... Magnetron, 15... Stirring body, 1 7... Temperature sensor (drying temperature detection means) 1 7 a... Buffer plate.

Claims (1)

[Claims] (1) A drying chamber to which a granular or powdery material to be dried is supplied;
a microwave supply means for supplying microwaves for microwave drying the material to be dried into the drying chamber; a stirring means for stirring the material to be dried in the drying chamber; A microwave drying device comprising a drying temperature detecting means for detecting the drying temperature of an object, and a buffer disposed near the drying temperature detecting means on the side toward which the object to be dried 5 is moved by stirring.