JPH02220813A - Microwave drying device - Google Patents

Abstract

PURPOSE:To prevent materials to be dried from absorbing moisture when being left in a drying chamber after the completion of drying by providing a heat insulation control means and heat insulating the material to be dried in the drying chamber at the time of unallowable decision for feeding out by a determining means. CONSTITUTION:When materials 5 to be dried are stored are stored in a reserve chamber 23 and materials 5 to be dried are further to be fed out from a drying chamber 3, a decision not to allow feeding out the materials 5 dried from the drying chamber 3 to the reserve chamber 23 is determined by a computer. The, the dried materials 5 are left as they are in the drying chamber 3 even after being dried. When discharging is put into practice, the materials 5 to be dried, dried once, is cooled naturally and absorbs moisture again, and at the same time, the materials 5 are heat insulated at the drying temperature by means of microwaves to prevent the materials 5 dried from absorbing moisture again in the drying chamber 3.

Description

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

(b) Prior art Japanese Utility Model Application Publication No. 59-91592 discloses a microwave drying apparatus that applies microwaves to a drying chamber into which the material to be dried is supplied, thereby drying the material to be dried using the microwave. There is. The material to be dried that has been subjected to microwave drying is then discharged from the drying chamber to a predetermined location, and the supply of microwaves into the drying chamber is stopped.

However, in this case, if the material to be dried that was previously discharged remains accumulated in the predetermined location, the material to be dried will be immediately discharged to the predetermined location even if the material to be dried has just finished drying in the drying chamber. Therefore, the dried material must be left as is in the drying chamber.

This has the drawback that even if the material to be dried is dried, it absorbs moisture again while it is left in the drying chamber.

(C) Problems to be Solved by the Invention The present invention attempts to prevent the material to be dried from absorbing moisture again even if the material to be dried is left in the drying chamber even after microwave drying is completed. It is.

(d) Means for Solving the Problems The microwave drying apparatus of the present invention includes a drying chamber into which a granular or powdery material to be dried is supplied, and a microwave for microwave drying the material to be dried in the drying chamber. a microwave supply means for supplying waves; a discharge section from which the material to be dried dried in the drying chamber is discharged; and a determination for determining whether or not discharge of the material to be dried to the discharge section is permitted. means, a discharge means for discharging the dried material to the discharge section when the determining means determines whether discharge is permissible, and a heat retention control means for keeping the dried material warm in the drying chamber when the determining means determines that discharge is not permissible. Equipped with

(E) Function When the drying material is allowed to be discharged to the discharge section when drying of the dried material is completed, the dried material is immediately discharged to the discharge section.

On the other hand, if the material to be dried that was previously discharged remains in the discharge section, the material to be dried will not be allowed to be discharged to the discharge section when the drying of the material to be dried is completed, and the material to be dried will be After drying, they are kept warm in the drying room. Therefore, even if the material to be dried is left in the drying chamber, it does not absorb moisture again.

(F) 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 peripheral mechanisms thereof.

The drying device main body (1) is provided with a cylindrical drying chamber (3) having an upper lid (2) as a main part. 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 to be dried (5) is stored. Examples of the material to be dried (5) include resin pellets, rice, and powdered pharmaceutical products. The resin pellet is molded after being melted, but if the resin pellet is dried prior to such melt molding, subsequent molding will be performed better. In this embodiment, a resin pellet is selected as the material to be dried (5).

Further, a suction hopper (7) is connected to the center of the upper lid (2) of the drying chamber (3). A filter paper (8) having a mesh smaller than the diameter of the material to be dried (5) is disposed within the hopper, and a poppet valve (9) is provided above the filter paper. Then, above the poppet valve (9), the suction hopper (7)
A suction blower (11) is connected to the suction blower (11) via an intake pipe (10). In this case, if the blower (11) is driven with the poppet valve (9) open, the suction action of the blower (11) will affect the suction pipe (10), the suction hopper (7), and the drying chamber (3). ) through the supply pipe (4
), and the material to be dried (5) in the storage tank (6) passes through the supply pipe (4) and reaches the drying chamber (3). Material to be dried (
When the particles 5) reach the drying chamber (3), they fall under their own weight and accumulate in the drying chamber.

In the drying chamber (3), microwaves are supplied to the interior from a magnetron (12) via a waveguide (13), and a motor (14) drives a motor (14) to the bottom wall of the drying chamber (3). ) is provided, and a level sensor (16) and a temperature sensor (17) such as a thermistor are arranged on the side wall. Such a level sensor (16)
detects whether a predetermined amount of the material to be dried (5) has accumulated in the drying chamber (3), and the temperature sensor (17) detects whether or not the material to be dried (5) has accumulated in the drying chamber (3).
Detects the temperature of Further, a compressor (19) is connected to the left bottom of the drying chamber (3) via an intake valve (18), and an exhaust valve (20) is provided on the top lid (2) of the drying chamber (3). . Driving these compressors (19),
The intake valve (18) and the exhaust valve (20) are opened when the material to be dried (5) is dried using microwaves, and the water vapor generated during drying is opened together with the air from the compressor (19). (20) and is discharged to the outside.

Furthermore, a discharge valve (21) is provided at the bottom right of the drying chamber (3), and the discharge valve discharges the dried material (
5) It is opened when discharging. The material to be dried (5) discharged upon opening of the discharge valve (21) falls through the discharge pipe (22) into the preliminary chamber (23), which is a lower discharge section, and accumulates therein. A heat insulating heater (
24), and the preliminary chamber (23) is provided with a level sensor (26) having a rotating body (25). Such a level sensor (26) is usually a rotating body (
25), a small predetermined amount of the material to be dried (5) accumulates in the preliminary chamber (23), and the material to be dried (5) becomes a load even when trying to rotate the rotating body (25). rotating body (25
) is in a state where it cannot be rotated satisfactorily, a predetermined signal is output, and it is detected 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 a conveying pipe (28) to another suction hopper (27) located higher than the preliminary chamber (23).
) are connected through. Similar to the suction hopper (7), the suction hopper (27) is also provided with a filter paper (29) having a mesh smaller than the material diameter of the material to be dried (5), and is located above the filter paper. A poppet valve (30) is provided. At the top of the poppet valve (30), the suction blower (11) is also connected to the suction hopper (27) via an intake pipe (31). In this case, when the blower (11) is driven with the poppet valve (30) open, the suction action of the blower (11) is transferred to the conveying pipe (28) via the suction pipe (31) and the suction hopper (27). ), and the material to be dried (5) accumulated in the preliminary chamber (23) is transferred to the conveying pipe (2
8) and reaches the suction hopper (27). When the material to be dried (5) reaches the suction hopper (27), it falls into the hopper due to its own weight. And the suction hopper (27)
A heat retaining heater (32) is arranged on the lower inclined wall, an on-off valve (33) is provided at the lower end, and upper and lower limit level sensors (34) and (35) are arranged at the lower part. When the on-off valve (33) is closed, the suction action works and the drying material (5) is activated in the suction hopper (27).
) falls into the suction hopper (27) and the material to be dried (5)
On the other hand, when the on-off valve (33) is opened, the material to be dried (5) accumulated in this way falls downward and reaches the next processing section, where the material to be dried is dried in the processing section. (5) That is, the resin pellet is melt-molded.

Figure 2 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 the operation section (37) disposed on the front of the drying device main body (1) and temperature information from the temperature sensor (17). , the above various level sensors (16
) (26) (34) (35) Based on the information etc.
The above magnetron (12), motor (14), intake valve (18), exhaust valve (20), compressor (19), discharge valve (21), heat retention heater (24) (32), suction blower (11), Poppet valves (9) (30), on-off valves (33
) to drive and control.

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 turning on the power, it goes through the S1 step, then normally S2, S3, and S.
Steps 3a, S4, and S5 are executed cyclically. S1
In this step, an initial setting operation is performed. That is, all writable areas in the microcomputer (36) are cleared, and the magnetron (12), motor (14), compressor (19), and heater (24) are cleared.
) (32), the suction blower (11) is placed in a stopped state, and the intake valve (18), exhaust valve (20), discharge valve (21), poppet valve (9) (30), on-off valve (33) )
are each placed in a closed state. In step S2, operation information from the operation section (37) is input, and in step S3, the lower limit level sensor (35) is used to control the suction hopper (2).
7), it is determined whether or not the material to be dried (5) is accumulated, and in step S3a, based on the detection by the level sensor (26), it is determined whether or not there is a small amount of material to be dried (5) in the preliminary chamber (23). It is determined whether a certain amount has been accumulated. In step S4, it is checked whether a start flag is set in the computer (36), and in step S5, it is determined whether or not the start key is currently being operated by the operation unit (37) based on the input information in step S2. Ru.

Therefore, when melt-molding the object to be dried (5), which is a resin pellet, in order to dry the object to be dried (5) in advance so that such molding can be performed well, first, the operation part (37) is Then, set the desired drying time and drying temperature within the range of 20 to 60 minutes and 70 to 170° C. using the keys, and turn on the continuous switch (38). These operating information are input in step S2. Then the operation section (37)
When the start key is operated in step 52, the information is similarly inputted, an affirmative judgment is made in step S5, a start flag is set in step S6, and each of the above-mentioned heat retention heaters ( 24) (32
) drive control is started. That is, the preliminary room (23)
and each of the above-mentioned heat retention heaters (24) (3) so that the inside of the suction hopper (27) is maintained approximately at the set drying temperature.
2) is intermittently driven at a desired ratio, so that the preliminary chamber (23)
And the inside of the suction hopper (27) is kept warm at the above temperature.

Next, steps S8, S9, and S10 are sequentially executed. In step S8, it is checked whether the transport flag in the computer (36) is set (in this case, it is checked that it is not set).

In step S9, the operation of supplying the material to be dried (5) to the drying chamber (3) is executed. That is, the poppet valve (9) is opened and 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 upper surface of the material to be dried (5) fed into the container is aligned with a smooth horizontal surface. At step 510, the level sensor (16) detects that the upper surface of the object to be dried (5) is detected by this sensor (16).
It is determined whether or not a predetermined number of objects (5) to be dried have accumulated in the drying chamber (3) (in this case, it is determined that a predetermined number of objects (5) have not accumulated in the drying chamber (3)).

After that, S2, S3, S3a, S4, Sll, S8~S
Each step of IO is executed circularly. At this time, in the Sll step, it is checked whether the supply end flag in the computer (36) is set. When a predetermined number of items to be dried (5) accumulates in the drying chamber (3) and this is determined in step 510, steps S12 and S13 are then executed. In step S12, 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, S3a%S4, Sll, S14~
Each step of S17 is executed cyclically.

At this time, in step S14, it is checked whether the drying end flag in the computer (36) is set, and in step S15, the drying operation is executed. That is, the temperature sensor (1
Depending on whether the temperature of the material to be dried (5) detected by the magnetron (12) has reached the set drying temperature
) is driven intermittently, the material to be dried (5) is maintained at the drying temperature and subjected to microwave drying, and the motor (14) is driven again to rotate the stirring body (15) to dry the material to be dried (5). At the same time, the compressor (19) is driven and the intake valve (18) and exhaust valve (20) are opened, so that the water vapor generated from the material to be dried (5) is discharged to the outside. be discharged. Furthermore, in step S15, along with this drying operation, measurement of the elapsed drying time is started. 8
In step S16, it is determined whether the elapsed drying time has reached the set drying time, and in step S17, it is determined whether the drying time has reached the set drying time or not.
As in the 8th step, it is checked whether the transport flag is set or not.

Therefore, when the elapsed drying time reaches the set drying time, S
After 16 steps 518, step S19 is 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. At step 519, the drying end flag is set.

And S17, S2, S3, S3a, S4, Sll,
After passing through 514 steps, S20, 321, S22, S
Steps 23 and S24 are sequentially executed. In step S20, it is checked whether the discharge flag in the computer (36) is set.

Step 521 corresponds to the determination means of the present invention, and this step S2
In the first step, it is determined whether a predetermined amount of the material to be dried (5) has already accumulated in the preparatory chamber (23) based on the detection by the level sensor (26). 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 corresponds to the discharge means of the present invention, and since the predetermined number of materials (5) to be dried is not accumulated in the preliminary chamber (23) in step S21, the drying chamber (3) is discharged from the preliminary chamber (23).
This step is executed when the dried material to be dried (5) is allowed to be newly discharged from the drying chamber (3).In step S23, the dried material to be dried (5) is discharged from the drying chamber (3). An operation of discharging to the preliminary chamber (23) is performed. That is, the discharge valve (21) is opened and the motor (14)
is successively driven to rotate the agitator (15), and as the agitator (15) rotates, the material to be dried (5) near the agitator (15) is pushed to the surroundings, and the material to be dried is The material (5) is passed from the discharge valve (21) through the discharge pipe (22) to the preliminary chamber (
23) and is discharged. The material to be dried (5) discharged in this way does not naturally cool down because the preliminary chamber (23) has been kept warm since step S7, and the material to be dried (5) is naturally cooled. This prevents moisture from being absorbed again. Furthermore, in step S23, the elapsed time of such discharge is started to be counted. In step S24,
Has the elapsed discharge time reached a predetermined discharge time (this is a 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, 34, Sll, 514,
Each step of S20, S23, S24, and S17 is executed in circulation, and when a small predetermined amount of the material to be dried (5) accumulates in the preparatory chamber (23) as a result of the above-mentioned discharge, in this circulation, steps S3a and S25 are executed. , S26, S27, and S28 are sequentially executed. In step S25, a conveyance flag is set, and in step S26, 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 warmed preliminary chamber (23) to the suction hopper (27).

That is, the poppet valve (30) is opened and the suction blower (1) is opened.
1) is driven, and the material to be dried (5) is transported from the preliminary chamber (23) to the suction hopper (27) by the suction action of the blower (11). The material to be dried (5) transported in this way is
Since the suction hopper (27) has been kept warm since step S7, natural cooling is not performed and the material to be dried is prevented from absorbing moisture again. In step S28, it is determined by the detection of the upper limit level sensor (34) whether or not the material to be dried (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
, S24, S17, S27, and S28 are executed in circulation, and during this period, the discharge operation to the preliminary chamber (23) and the conveyance operation to the suction hopper (27) are processed in parallel, and the discharge operation to the preliminary chamber (23) is performed in parallel. The dried material (5) is immediately conveyed to the suction hopper (27).

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)), S29, S30,
Each step of 531 is executed sequentially. In step S29, the ejection operation executed in step S23 and the elapsed elapsed time measurement are completed, and the measured time is reset. In step S30, 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 section (37).

In this case, the continuous switch (38) is in the on state, and then after passing through step S17, S4, S11, S8, and
Steps 27 and S28 are executed cyclically. and,
The material to be dried (5) in the preliminary chamber (23) is transported,
When the dried material (5) accumulates in the suction hopper (27) up to the position of the upper limit level sensor (34), the steps from S28 to S3
2. Step S33 is executed. In step S32, the conveyance operation executed in step S27 is stopped, and in step S33, the conveyance flag is reset.

The material to be dried (5) thus collected in the suction hopper (27) is melt-molded in the next processing section.
This is the upper limit level sensor (3) inside the suction hopper (27).
The computer (
36) is executed when given within. That is, at this time, the on-off valve (33) is opened by the computer (36), and the dried material (5) is discharged from (1) and the hopper (27) to the next stage processing section. The opening/closing valve (33) is closed again when all of the material to be dried (5) in the suction hopper (27) is discharged. And the above-mentioned released material to be dried (5)
are melt-molded in the next processing section, and in this case, the sugar beet pellets, that is, the material to be dried (5), are dried in advance, so that the molding can be performed well.

Now, if the processing capacity of the next-stage processing section for the melt-molding is slow, the steps from the drying material supply operation to the conveyance operation are repeated, so that the suction hopper (27) and the preliminary chamber (23) are The material to be dried (5) remains accumulated.

Therefore, when the drying material (5) is accumulated in the preliminary chamber (23) and the drying material (5) is about to be discharged from the drying chamber (3), this is determined in step S21. In other words, it is determined that more than a predetermined amount of the material to be dried (5) has accumulated in the preliminary chamber (23) and that the material to be dried (5) is not allowed to be newly discharged from the drying chamber (3) to the preliminary chamber (23). be done. Then, the dried material (5) is left as it is in the drying chamber (3) even after drying. If such neglect is simply carried out,
Even if the material to be dried (5) is dried, it naturally cools down and absorbs moisture again, but in order to prevent this, the present invention
34 steps are executed. That is, step S34 corresponds to the heat retention control means of the present invention, and in step S34, the same control as the drying operation in step 515 is performed, and the material to be dried (5) is heated to the set drying temperature by microwaves. The temperature is maintained, and 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 step 831 is executed at such off time, step S35 is executed next,
The start flag is reset and the respective heat-retaining heaters (24) and (32) are stopped. Then S2
, S3, S3a, S4 and S5 steps are executed cyclically.

(G) Effects of the Invention According to the present invention, even if the material to be dried is left in the drying chamber even after microwave drying is completed, it is possible to prevent the material to be dried from absorbing moisture again. A practical microwave drying device can be provided.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a sectional view, FIG. 2 is a circuit diagram, and FIG. 3 is a flowchart of an operating program of a microcomputer. (3)...Drying room, (
12)...Magnetron, (23)...Preliminary chamber (discharge section'), (36)...Microcomputer.

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 to the drying chamber; a discharge section from which the dried material is discharged; a determining means for determining whether or not the discharge of the dried material to the discharge section is permitted; A microwave drying apparatus comprising: a discharge means for discharging the material to the discharge portion; and a heat retention control means for retaining the temperature of the material to be dried in the drying chamber when the determination means determines that discharge is not permitted.