JPS6364709B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in fluidized bed drying equipment. Drying treatment using the fluidized bed method is a method that effectively transfers heat by fluidizing the powder or granular material to be dried using hot air, and quickly evaporates and removes moisture. It's getting old. An example of a conventional device will be explained based on FIG. Powder 14 containing moisture etc. is supplied from the input port 1 of the drying furnace 13 , and the powder 14 is dispersed and supplied into the furnace by the rotating disperser 2. Hot air is supplied from the bottom of the furnace through the air outlet 7 through the heater 7a, and is distributed and sent into the furnace 13 through the perforated plate 4. Then, the powder 14 is suspended by the hot air, that is, dried while receiving heat in a fluidized bed state. A part of the granular material 14 passes through a long path to the partition plate 5 provided to increase drying efficiency.
It flows to the right while passing over the top, and finally reaches the outlet side hopper 8, and is discharged from the discharge port 20 via the rotary valve 12a into the receiving tray 10a. In addition, coarse particles are removed from the partition plate hole 9a provided at the bottom of the furnace and the discharge hole 9b.
from the rotary valve 12b to the saucer 10b via
is discharged. Furthermore, the hot air whirling up fine particles in the furnace is separated into hot air and fine powder by a gas/solid separator 6 equipped with a cyclone or filter installed on the ceiling of the furnace. The hot air is taken out of the furnace through the exhaust pipe 11a, a part of which is returned to the hot air outlet 7 and sent into the furnace again as shown by the dotted line 11b, and a part is discharged as shown by the arrow 11c. The fine powder produced in the separator 6 is then taken out of the furnace. A heating coil 3 for supplementary heating of the fluidized powder and hot air is provided in the furnace, and steam is circulated as shown by an arrow 3a. There are the following drawbacks when using the drying apparatus based on the fluidized bed method described above. (1) When the material to be dried fed into the inlet of the drying oven has a high moisture content or is not sufficiently pulverized, large lumps may remain. Since the inside of these lumps is not particularly dried, a fluidized bed state cannot be obtained, and the transmission efficiency is reduced, so they cannot be heated and dried, and the so-called caking phenomenon occurs in which they come out in the same shape, making them impossible to flow. be. (2) If the material to be dried is coarse particles, it takes a long time to completely dry the center. Therefore, the efficiency is poor and the size of the ikioi device has to be increased. (2) As an auxiliary means for supplying heat to large lumps in (1) above, a heater with fins or the like may be used, but this may become an obstacle and make it difficult to obtain a stable fluidized bed state. Therefore, it has been desired to realize a device that solves these drawbacks. The present invention has been made in view of the above-mentioned conventional drawbacks, and provides a fluidized bed drying apparatus that uses microwave heating in combination to efficiently dry powder and granular materials. An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. It should be noted that the same reference numerals in the drawings refer to the same parts as in FIG. 1 and other figures to simplify the explanation. Therefore, the drying oven 1 consisting of walls made of conductive material
A microwave power supply port 15a is provided in a part of the ceiling of the microwave oscillator 1 through the waveguide 15.
8 are arranged in a row. Then, the blower 17 blows wind through the waveguide 15 into the furnace 13 so that the powder and granular material 14 in the furnace 13 does not enter the waveguide 15.
It is designed to be sent inside. The partition plate 16 partitions the waveguide with a dielectric plate with low microwave loss, thereby preventing wind from blowing toward the microwave oscillator 18. This structure is the third
This will be explained in more detail with reference to the drawings. The waveguide 15 is L in the middle.
It is bent into a letter shape, and a large number of ventilation holes with dimensions that do not transmit microwaves are formed in the tapered surface 15b,
A duct 17a that sends air from the blower 17 into the waveguide through the ventilation hole is connected to the outer surface. A partition plate 16 made of a low-loss dielectric plate is provided in the middle of the waveguide extending from the wind introducing portion toward the oscillator 18 to prevent the wind from flowing toward the oscillator. In this way, the air from the blower is constantly flowing from the waveguide into the furnace 13 in the direction of the arrow f, causing the material to be dried to adhere to the inner wall surface of the waveguide 15 or the surface of the partition plate 16, or to the oscillator 18. We are trying to prevent it from entering. This allows microwave power to be stably introduced into the furnace without loss. To explain the operation of the above device, when the material to be dried, that is, the powder 14 containing moisture etc. is fed into the furnace 13 from the input port 1, it is dispersed and supplied to the left side of the furnace 13 by the disperser 2. . In this state, when hot air is supplied through the perforated plate 4 at the bottom of the furnace, the powder and granules 14 are dried while becoming a fluidized bed, and are successively sent to the right over the partition plate 5, and finally to the exit side. It reaches the hopper 8 and is discharged from the discharge port 20 via the rotary valve 12. Here, if lumps are mixed in when the powder or granular material 14 is supplied by the disperser 2, a fluidized bed state may not be obtained and drying may not be possible. However, in this apparatus, since microwave power is supplied into the furnace, the microwaves are selectively and well absorbed by the lumps. As a result, the lumps are efficiently dried by internal heating, which is a feature of microwave heating, and the pressure inside the lumps increases slightly, causing cracks and breaking the lumps into smaller pieces. When the particles are finely divided, they often mix into the fluidized bed state, which has the effect of reliably maintaining the fluidized bed state. Furthermore, even if a fluidized bed is formed with a relatively large powder, it will take time to dry the powder to the center if only hot air is used due to poor heat conduction, but microwave power is According to the present invention used in combination, the feature of internal heating is utilized and drying can be performed in a short time. Therefore, since the residence time can be shortened, the apparatus can also be relatively miniaturized. As described above, by using the apparatus of the present invention, the caking phenomenon is less likely to occur, and even relatively large particles can be heated and dried while being fragmented, making it possible to achieve high efficiency and miniaturization of the apparatus. . Furthermore, since there is no need for obstacles such as an Elofine heater as an auxiliary heating means, it has become possible to obtain a stable fluidized bed state. Note that the powder inlet, outlet, bottom, and separator 6 of the furnace 13 have pipe lengths L, L',
Make the inner diameters D and D' cut-off dimensions, or take other radio wave leakage measures. If the porous plate 4 at the bottom is made of a conductive material, the dimensions of the holes may be set to cut-off dimensions, and if it is made of a dielectric material, the furnace wall 7b below it for blowing up the hot air may be made conductive. It is sufficient to make the air pipe 7 with a cut-off size. In addition, although the waveguide 15 is connected to the ceiling of the furnace 13 in FIG. 2, the waveguide 15 is extended to the center of the furnace so as to directly supply power to the powder part in the fluidized bed state. You may also set it up. Furthermore, in the above explanation, the object to be dried is powder or granular material, but the object is not limited to this, and a nozzle 19 as additionally shown in the same figure is provided to spray the solution in the form of an atmosphere and evaporate and dry it. You can also do so. In this case, it goes without saying that it is better to place the dry powder into the furnace 13 in advance to form a fluidized bed when starting the drying process. The above example is a case of a horizontal two-stage fluidized bed drying apparatus in which the furnace is separated by partition plates, but the drying apparatus is not limited to this, and can be used in various combinations such as vertical type, horizontal type, single-stage type, and multi-stage type. The present invention can be implemented in a device.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a conventional structure, FIG. 2 is a schematic cross-sectional view showing an embodiment of the present invention, and FIG. 3 is a cross-sectional view of the main part thereof. 4; Perforated plate, 6; Gas/solid separator, 7; Blow pipe, 13 ; Drying oven, 14; Powder, 15; Waveguide, 18; Microwave oscillator, 16; Partition plate.

Claims (1)

[Claims] 1. A drying furnace made of a conductive wall and having a part thereof having an input port for feeding the object to be dried, an outlet and a discharge hole for discharging the object to be dried, and a bottom formed of a perforated plate; Gas installed in a part of the furnace /
A solid separator, a partition plate provided above the bottom perforated plate of the drying furnace, a partition plate hole provided below the partition plate, and gas into the furnace from the bottom perforated plate of the drying furnace. In the fluidized bed drying apparatus, a microwave oscillator is connected via a waveguide so as to supply microwave power to the drying furnace, and the waveguide is connected to an L A large number of ventilation holes with dimensions that do not transmit microwaves are formed on the tapered surface, and a duct is connected to the outer surface of the tapered portion to send the air from the blower into the waveguide through the ventilation holes. The drying device described above, characterized in that a partition plate made of a low-loss dielectric material is provided in the middle of the waveguide extending from the introduction part toward the microwave oscillator.