JPH0642867A - Tumbler type rotary dryer - Google Patents

Abstract

PURPOSE:To perform energy conservation and to shorten a drying time by abruptly reducing an internal pressure of a dryer body to a predetermined pressure at the time of freeze drying, and holding a constant rate period drying product temperature of a material to be dried at a predetermined temperature. CONSTITUTION:A material to be dried is charged in a rotatable dryer body 20, an inlet 6 is closed, the air in the body 20 is then discharged through large- diameter exhaust tubes 1', 1'', a condenser 3 having large condensing capacity and a vacuum pump 4 having a large exhaust capacity, an internal pressure of the body 20 is abruptly reduced to about 1-0.1Torr, and a temperature of the material to be dried is held at about -15-125 deg.C. Then, the body 20 is rotated, heating medium is fed into a heating jacket 21 provided at its outer wall, and frozen moisture in the material to be driven is evaporated by conduction heat and radiation heat. Thus, energy conservation can be performed, and a drying time can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tumbler type rotary dryer used in the fields of food material processing, pharmaceutical manufacturing, chemical product manufacturing and the like.

[0002]

2. Description of the Related Art In the fields of food material processing, pharmaceutical manufacturing, chemical product manufacturing, etc., (a) hot air drying method, (b) hot plate (shelf) and drying plate (tray) are used for drying the workpiece. Vacuum freeze-drying method utilizing (c) rotary dryer is used.
In the hot air drying method of the above (a), after the material to be dried is divided into small portions in a drying dish (tray), placed in a dryer and dried with hot air. After drying, the drying dish is manually dried. I try to remove it from the machine.

In the above-mentioned vacuum freeze-drying method (b), the frozen material to be dried is evenly placed on a drying dish (tray) with a thickness of 5 to 20 m.
After being placed in the m, it is placed on a hot plate (shelf) in the dryer, the vacuum pump is operated, the air in the dryer is exhausted, the internal pressure (vacuum pressure) of the dryer is lowered, and the material is dried. The frozen water in the product is evaporated (sublimated), and after drying, the drying dish is taken out from the dryer.

In the rotary drying method (c), the material to be dried is put into a rotatable dryer main body, the charging port is closed, and then the condenser and the vacuum pump are operated to make the dryer main body. The air inside is exhausted through an exhaust pipe, a condenser, and a vacuum pump to reduce the internal pressure of the dryer main body to about 10 to 70 torr, and then the dryer main body is rotated to stir the material to be dried. While mixing, the temperature of the material to be dried in the dryer main body is maintained at about 15 ° C to 50 ° C to evaporate the moisture in the material to be dried, and when the drying is completed by the progress of this evaporation, the condenser Also, the vacuum pump is stopped and the inside of the dryer main body is brought to atmospheric pressure so that the material to be dried is taken out from the inside of the dryer main body.

[0005]

In the hot air drying method (a), the material to be dried is dried by hot air, so that the material to be dried is discolored or the aroma is reduced, resulting in deterioration of quality. There was a problem. The vacuum freeze-drying method of the above (b) has the advantage that the quality does not deteriorate unlike the above hot air drying method, but the vacuum-frozen material to be dried is placed in a drying dish (tray) to a uniform thickness of 5 to 20 mm. Since it is placed on a hot plate (shelf), the number of dry plates is 20 ~
If the number of dried dishes becomes as large as about 100, it takes a lot of manpower and time to put in and take out the dry dishes. Further, since this vacuum freeze-drying method is of a stationary type, the thermal conductivity from the hot plate (shelf) to the vacuum-frozen object to be dried (porous object to be dried) is small, resulting in a longer drying time. There was a problem.

The rotary drying method (c) has the advantage that the material to be dried can be charged into the dryer main body at one time through the input port, and can be taken out from the dryer main body through the discharge port at once. However, the exhaust pipe is thin. The condensing capacity of the condenser is small. The exhaust capacity of the vacuum pump is small. Therefore, the internal pressure of the dryer body is 10 to 70t
There was a problem that the vacuum drying could not be carried out quickly because the temperature could only be reduced to about orr and the temperature of the material to be dried was kept at about 15 to 50 ° C.

The present invention has been proposed in view of the above problems, and the object of the invention is to obtain a dried product of good quality. Another object is to provide a tumbler type rotary dryer which can save labor and shorten the drying time.

[0008]

In order to achieve the above object, the present invention provides a dryer main body which rotates around a rotary shaft and agitates and mixes an object to be dried, and the rotary shaft. An internal exhaust pipe passing through the inside, an external exhaust pipe connected to the internal exhaust pipe via a rotary joint, a condenser connected to the external exhaust pipe, a vacuum pump connected to the condenser, and the dryer body. In a tumbler type rotary dryer having a heating jacket for evaporating the water content of the material to be dried provided on the outer wall, the inner exhaust pipe and the outer exhaust pipe are made thicker, and a condenser having a large condensing capacity is used. Then, by using a vacuum pump having a large exhaust capacity, the internal pressure of the dryer main body is rapidly reduced to about 1 torr to 0.1 torr during freeze-drying, thereby performing constant rate drying of the material to be dried. Product temperature -1 It is characterized in that ° C. maintained at about ~-25 ° C..

[0009]

The tumbler type rotary dryer according to the present invention is constructed as described above. The material to be dried is put into the rotatable dryer body, the charging port is closed, and then the dryer body inside the dryer body is closed. Exhaust air through a large-diameter exhaust pipe → a condenser with a large condensing capacity → a vacuum pump with a large evacuation capacity, and rapidly reduce the internal pressure of the dryer main body to about 1 torr to 0.1 torr, and the above-mentioned to be dried. Constant rate dry product temperature -1
Hold at about 5 ℃ ~ -25 ℃, then rotating the dryer main body, while stirring and mixing the material to be dried, the heating medium is circulated in the heating jacket provided on the outer wall of the dryer main body, The heat transfer and radiant heat from the heating jacket evaporate (sublimate) the frozen water in the material to be dried to dry the material to be dried, and the temperature of the material to be dried is near the heating temperature due to the progress of this evaporation. When the drying is completed, the operation of the condenser and the vacuum pump is stopped, the inside of the dryer main body is brought to atmospheric pressure, and the material to be dried is taken out of the dryer main body.

[0010]

EXAMPLE Next, the tumbler type rotary dryer of the present invention is shown in FIG.
3 will be described with reference to FIG. 3. 1 is a tumbler type rotary dryer, 20 is a dryer main body of the tumbler type rotary dryer 1, 16 and 16 are mounts, and 15 and 15 are same mounts 1.
Bearings 6 and 16 are provided on the bearings 15. The bearings 15 rotatably support left and right rotating shafts protruding outward from the left and right side portions of the dryer body 20.

Reference numeral 1 denotes a large-diameter internal exhaust pipe arranged in the dryer main body 20, and 1'is an external exhaust pipe communicating with the internal exhaust pipe 1 '. thick. The external exhaust pipe 1 ″ penetrates through the rotary shaft on the left side of the dryer main body 20. 2 is an exhaust filter attached to the tip of the internal exhaust pipe 1 ', and 21 is the dryer main body 20.
The heating jacket 6 is provided on the inner surface of the drying machine, the inlets 6 and 7 provided on the dryer main body 20 are the outlets 7 provided on the dryer main body 20.

Reference numeral 8 is a rotary joint interposed between the internal exhaust pipe 1'and the external exhaust pipe 1 '', and 10 is a drive motor installed on the mount 16.
Is a speed reducer for reducing the rotation of the drive motor 10, and 17 is power for transmitting the rotation of the speed reducer 11 to the rotary shaft on the right side of the dryer main body 20 to rotate the dryer main body 20 about the left and right rotary shafts. It is a transmission device.

2 in FIG. 3 is a heating device for heating the heating medium to an arbitrary temperature by steam or electric power, 9 in FIG. 1 is a joint for heating medium, and 12, 13 and 14 are heating media obtained by the heating device 2. A heating device 2-> heating jacket 21-> a heating medium circulating flexible tube for circulating the heating device 2.
3 of FIG. 3 is a condenser (condenser) that solidifies 70 to 95% of the evaporated water vapor to form ice, and the condenser 3 has a large condensing capacity. Reference numeral 5 is a refrigerator (cooling tower) for cooling the condenser 3.

Reference numeral 18 in FIG. 1 denotes an exhaust flexible tube for connecting the external exhaust pipe 1 ″ and the condenser 3 to each other, and a vacuum pump 4 connected to the condenser 3 for the exhaust capacity of the vacuum pump 4. large. Reference numeral 19 is a temperature detection sensor installed in the dryer main body 20. Next, the operation of the tumbler type rotary dryer shown in FIGS. 1 to 3 will be specifically described. First, the inside of the heating jacket 21 of the dryer main body 20 is cooled to room temperature (10
C. to 20.degree. C.), the non-frozen object to be dried is charged into the dryer main body 20 through the charging port 6, and the charging port 6 is closed.
Then, the refrigerator 5 is operated to cool the inside of the condenser 3. At the same time as this, the vacuum pump 4 is operated to move the air inside the dryer main body 20 to the internal exhaust pipe 1 ′ → rotating joint 8 → external exhaust pipe 1 ″ → exhaust flexible tube 18 → condenser 3
→ Exhaust to the outside of the vacuum pump 4.

After a few minutes have passed since the operation of the vacuum pump 4, the internal pressure (vacuum pressure) of the dryer main body 20
Becomes 4.6 torr, the water in the dried material evaporates,
The latent heat of vaporization at this time causes the temperature of the material to be dried to be about 0 ° C., and the freezing is started. The time for the internal pressure of the dryer main body 20 to reach 4.6 torr differs depending on whether a previously frozen material to be dried or an unfrozen material to be dried has been charged, and the previously frozen material to be dried is charged. In this case, the internal pressure of the dryer main body 20 will be 4.6 in about 5 minutes.
In the case where an object to be dried that has not been frozen is added, the internal pressure of the dryer main body 20 reaches 4.6 torr in about 10 to 30 minutes.

After that, the operation of the condenser 3 and the vacuum pump 4 is continued, and the internal pressure of the dryer main body 20 is changed to 4.6 torr.
The rate is rapidly lowered as r → 3 torr → 2 torr → 1 torr. During this time, the moisture in the material to be dried evaporates, the temperature of the material to be dried rapidly decreases due to the latent heat of vaporization at this time, and when the internal pressure of the dryer main body 20 drops to 1 torr, the material to be dried is The temperature drops to about -15 ° C to -17 ° C, and the water in the material to be dried is completely frozen (referred to as self-freezing).

In this state, the dryer main body 20 is rotated to stir and mix the material to be dried, and the heating medium is circulated in the heating jacket 21 provided on the outer wall of the dryer main body 20. The frozen water in the material to be dried by the conductive heat transfer and the radiant heat from the jacket 21 is changed to 1 to
Evaporation (sublimation) is performed under a vacuum pressure of rr, and as the evaporation (sublimation) proceeds, the temperature of the material to be dried rises to near the heating temperature (for example, a temperature about 3 to 7 ° C. lower than the heating temperature) and dried. When the above is completed, the operation of the condenser 3 and the vacuum pump 4 is stopped, the inside of the dryer main body 20 is brought to atmospheric pressure, and the material to be dried is taken out of the dryer main body 20 through the discharge port 7. The above operation is shown in FIG.

The temperature of the material to be dried varies depending on the internal pressure (vacuum pressure) in the dryer body 4, and the internal pressure is 2 to
When set to rr, the temperature of the dried object becomes about -10 ° C,
When the internal pressure is set to 1.5 torr, the temperature of the material to be dried becomes about -17 ° C, and the sliced vegetables, the molded, granulated food, the chemical product, the medicine and the like become frozen pellets.

Incidentally, the volume of 1 kg of water which becomes a gas at 0 ° C. varies depending on the pressure P,

[0020]

[Equation 1]

760 torr: 1.244 m ³ , 100
torr: 9.45 m ³ , 10 torr: 94.57
m ³ , 1 torr: 945 m ³ . As described above, the volume of gas to be exhausted increases as the internal pressure of the dryer main body 20 decreases. In this respect, in the tumbler type rotary dryer of the present invention, the exhaust pipes 1 and 1 ′ are made thicker, the condenser 3 has a large condensing capacity, and the vacuum pump 4 has a large exhausting capacity. Then, during freeze-drying, the internal pressure of the dryer main body 20 is rapidly lowered to about 1 torr to 0.1 torr to maintain the constant temperature dry product temperature of the material to be dried at about -15 ° C to -25 ° C. I am trying to do it.

[0022]

As described above, the tumbler type rotary dryer of the present invention freezes the moisture of the material to be dried and directly evaporates (sublimates) the moisture in this frozen state, so that it is different from the conventional hot air drying method. And you can get good quality dried products. In addition, as described above, the material to be dried is put into the rotatable dryer main body, the inlet is closed, and then the air inside the dryer main body is exhausted with a large diameter → a condenser with a large condensation capacity → an exhaust capacity Evacuate via a large vacuum pump to increase the internal pressure of the dryer to 1
By rapidly lowering the temperature from about torr to about 0.1 torr, the constant temperature dried product temperature of the material to be dried is -15 ° C.
Since the temperature is maintained at about -25 ° C, labor can be saved and drying time can be shortened as compared with the conventional vacuum freeze-drying method and rotary drying method.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a tumbler type rotary dryer of the present invention.

FIG. 2 is a front view of the tumbler type rotary dryer.

FIG. 3 is a system diagram of the tumbler type rotary dryer.

FIG. 4 is an operation explanatory view of the tumbler type rotary dryer.

[Explanation of symbols]

 1 Tumbler Rotary Dryer 1'Internal Exhaust Pipe 1 '' External Exhaust Pipe 2 Heating Device 3 Condenser 4 Vacuum Pump 5 Refrigerator 6 Input Port 7 Discharge Port 8 Rotating Joint 9 Heating Medium Joint 10 Drive Motor 11 Reducer 12 -14 Heating medium circulation flexible tube 15 Bearing 16 Stand 17 Power transmission device 18 Exhaust flexible tube 19 Temperature detection sensor 20 Dryer main body 21 Heating jacket

Claims (1)

[Claims] 1. A dryer main body that rotates around a rotating shaft as a center and stirs and mixes an object to be dried, an inner exhaust pipe passing through the rotating shaft, and a rotary joint through the inner exhaust pipe. An external exhaust pipe connected to the external exhaust pipe, a condenser connected to the external exhaust pipe, a vacuum pump connected to the condenser, and a heating jacket for evaporating the moisture of the material to be dried provided on the outer wall of the dryer main body. In a tumbler type rotary dryer, the internal exhaust pipe and the external exhaust pipe are made thicker, a condenser having a large condensing capacity is used, and a vacuum pump having a large evacuation capacity is used to freeze. During drying, the internal pressure of the dryer main body is rapidly reduced to about 1 torr to 0.1 torr to maintain the constant temperature dry product temperature of the material to be dried at about -15 ° C to -25 ° C. Characterized tumbler Type rotary dryer.