JPH04295588A - Fluidized bed drying machine - Google Patents

Abstract

PURPOSE:To facilitate the formation of a fluidized by providing mechanical effect in addition to the ventilation of hot air. CONSTITUTION:A mixing device 6, effecting reciprocating motion in one cycle per 1-300 seconds, is provided in a drying chamber 3 above a perforated plate 2 of a fluidized bed drying machine 1 to provide mechanical effect in addition to hot air while dispersing and suspending non-dried materials (d) in the initial period of drying whereby the formation of the fluidized bed can be assisted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed dryer.

0002

[Prior Art] Conventional fluidized bed dryers are widely used as optimal for drying materials that are easy to fluidize, such as salts, amino acids, and powdered resins. It is partitioned approximately horizontally by a board, with the upper part serving as a drying chamber and the lower part serving as a wind box. Air, etc. is blown into the drying chamber from inside this wind box through the holes in the perforated plate, and the material to be dried is placed inside this drying chamber. A fluidized bed is formed by drying the material to be dried.

0003

[Problems to be Solved by the Invention] However, in the above-mentioned fluidized bed dryer, the material to be dried that is put into the drying chamber is dispersed and dispersed only by the hot air blown out from the many holes in the perforated plate.
Floating and forming a fluidized bed is an absolute requirement. For this reason, if the material to be dried has a high moisture content or is sticky, that is, if the material is difficult to form into a fluidized bed, the material to be dried will be absorbed by the many holes in the perforated plate. The hot air that blows out may cause the particles to solidify or adhere to the perforated plate, hindering fluidized bed drying.

[0004]The present invention was developed in view of the above-mentioned circumstances, and it is possible to easily transform a material to be dried into a fluidized bed and dry it even if the material to be dried has a relatively high moisture content or has some degree of stickiness. The purpose is to provide a fluidized bed dryer that can

[0005]

[Means for Solving the Problems] In order to solve the above problems, the fluidized bed dryer of the present invention partitions the inside of the room approximately horizontally with a perforated plate, with the upper part serving as a drying chamber and the lower part serving as a wind box. In a fluidized bed dryer, hot air is blown into a drying chamber from a wind box through holes in a perforated plate, and a material to be dried is put into the drying chamber to form a fluidized bed to dry the material to be dried. A stirring device that makes one cycle of reciprocating motion every 1 to 300 seconds is installed in the room to assist in dispersing and suspending the material to be dried in the early stages of drying.

[0006]

[Operation] According to the fluidized bed dryer configured as described above, when the material to be dried is put into the drying chamber in which hot air is blown out from the wind box through the holes in the perforated plate, most of the material to be dried is blown by the hot air. It is blown up and forms a fluidized bed. Some of them hit each other and solidify due to the hot air blown up, and become so large that they no longer blow up from the perforated plate.However, due to the stirring motion of the stirring device, the material to be dried is dispersed and blown up by the hot air. , forming a fluidized bed. The material to be dried that has formed a fluidized bed mixes vigorously with hot air and evaporates water from its surface.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view schematically showing a fluidized bed dryer of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. 1. In both figures, reference numeral 1 indicates a fluidized bed dryer, and the fluidized bed dryer 1 has a dryer main body 5 whose interior is partitioned approximately horizontally by a perforated plate 2, with a drying chamber 3 in the upper part and a wind box 4 in the lower part. The main components are a stirring device 6 installed in the dryer main body 5 to perform a stirring action, an inlet 7 for the material to be dried d provided in the dryer main body 5, and a product outlet 8 provided in the dryer main body 5.

The dryer main body 5 has a substantially rectangular parallelepiped shape and is made of a rust-resistant metal such as stainless steel, and is divided into upper and lower parts by a perforated plate 2 also made of a rust-resistant metal such as stainless steel. There is. As mentioned above, the upper part is a drying chamber 3 for drying the material to be dried d, and the upper surface of this drying chamber 3 is provided with discharge nozzles 9, 10, and 11 for discharging hot air. As mentioned above, the lower part serves as a wind box 4 for once receiving hot air and blowing out the hot air uniformly from the holes of the perforated plate 2. This wind box 4 is divided into two by a partition plate 12, and supply nozzles 13 and 14 for supplying hot air are provided on the lower surface of the box, respectively.

The stirring device 6 has a large number of stirring blades 17 attached at predetermined intervals to stirring rods 15 and 16 arranged approximately in parallel, and a drive device 18 for reciprocating the stirring blades 17 is attached to the stirring rods. Connected to 15 and 16. This drive device 18 reciprocates in the directions of arrows A and B in FIG. 1, and one cycle thereof is 1 to 300 seconds, preferably 3 to 4 seconds. If this cycle time is less than 1 second, the speed of the stirring blades 17 will be too fast, and the drying material d, which has a high moisture content, will be kneaded and solidified by drying. This is too slow and no mechanical stirring effect can be expected.

[0010] The shape of the stirring blades 17 is not particularly limited, and may be a linear shape with low resistance so that the material d to be dried is not kneaded and does not move significantly due to the reciprocating motion of the machine. It's good to have. Further, the drive device 18 is
Any device that makes reciprocating motion is sufficient, and pistons, cranks, etc. are usually used.

The input port 7 is used to input the material d to be dried, which has been made into a predetermined particle size using a granulator (not shown) or the like, into the base end side of the drying chamber 3. Further, the product outlet 8 is connected to the drying chamber 3.
from the proximal end to the distal end while flowing on the perforated plate 2,
During this process, the dried material d is discharged to the outside as a product.

The fluidized bed dryer 1 is assembled and used as shown in FIG. That is, the input port 7 of the fluidized bed dryer 1 is connected to the conveyor 21 via the input hopper 20. The supply nozzles 13 and 14 are connected to the delivery sides of blowers 24 and 25 via heaters 22 and 23, respectively, and blow air out from the perforated plate 2. An air filter 26 is provided on the suction side of the blowers 24 and 25.
27 are connected to each other to prevent dust in the air from entering the dryer main body 5. Furthermore, the discharge nozzles 9, 10 and 11 are gathered together at the pipe 28, and the cyclone 2
9, and collects the dried material d scattered during fluidized bed drying. An exhaust fan 30 and a rotary valve 31 are connected to the cyclone 29, respectively.
The dried material d collected at step 9 is periodically sent to the product outlet 8 of the drying chamber 3 through a pipe 32.

Next, the operation of the fluidized bed dryer 1 having the above structure will be explained. First, the material d to be dried is prepared, the blowers 24 and 25 of the apparatus shown in FIG. When the temperature exceeds the temperature, the input conveyor 21 and the exhaust fan 30 are operated, and the material to be dried d is input into the drying chamber 3 through the input port 7. Inside the drying chamber 3, hot air heated by heaters 22 and 23 is blown out from a large number of holes in the perforated plate 2 by blowers 24 and 25, so that the material to be dried d thrown into the drying chamber 3 floats and becomes a fluidized bed. do. However, some of the input materials to be dried adhere to each other and do not float well and try to stay on the perforated plate 2, but the material undergoes reciprocating motion for 1 to 300 seconds per cycle of the stirring device 6. The above-mentioned porous plate 2 is
The dried material d on the top is broken down and begins to float due to the hot air blown out from the holes of the perforated plate 2, and finally forms a fluidized bed. The material to be dried d flows from the proximal end of the drying chamber 3 near the input port 7 and moves to the product outlet 8 on the distal end side, where it is dried to below a certain moisture content and discharged from the product outlet 8, where it is packed into bags. It becomes a product. Incidentally, a part of the material to be dried d is scattered and discharged from the discharge nozzles 9 and 10.
, 11 enters the cyclone 29 via piping 28 and is separated and stored in its lower part. When a certain amount is reached, the rotary valve 31 is operated and the product is transported to the product outlet 8 via piping 32, and dried from the product outlet 8. It is discharged from the chamber 3 together with the fluidized dried material.

Next, a comparative experiment will be conducted between the fluidized bed dryer of the present invention and a conventional fluidized bed dryer. (Example) Using an apparatus having the flow shown in FIG. 3, 50 kg of a material to be dried (agar) having a water content of 73% by weight was dried with superheated steam at 110 degrees Celsius to a target water content of 10% by weight. After drying, samples of 10 g each are taken from five locations to measure the water content, and the amount of superheated steam used is also measured. Similarly, samples of 100 g each from five locations are taken from the dried material after drying and passed through a 2-mesh sieve to measure the proportion (percentage) of the residue.

(Comparative Example) Drying was carried out under the same conditions as in the above example using a fluidized bed dryer 1 in which the stirring device 6 was removed from the flow shown in FIG. 3, and measurements were taken.

The results are shown in Tables 1 and 2 below. As is clear from Tables 1 and 2, in order to increase the moisture content of the material to be dried from 73.0% to 10.0% by weight before drying, the fluidized bed dryer of the present invention requires 4
．． The amount of steam used is 5 kg, whereas the conventional method uses 5.8 kg, resulting in high drying efficiency.

[0017] Furthermore, the residual rate of the dried material after being sieved through a 2-mesh sieve is 3.2% in the case of the present invention, whereas it is 23.4% in the conventional method. ,
In the present invention, the degree of solidification of the dried materials is low, indicating that the fluidity state is good, and it can be considered that the above-mentioned high drying efficiency is a result of this.

[0018]

[Effect of the invention] According to the fluidized bed dryer having the above structure,
When the material to be dried is put into a drying chamber in which hot air is blown from the wind box through the holes in the perforated plate, most of the material to be dried is blown up by the hot air and forms a fluidized bed. Some of them hit each other and solidify due to the hot air blown up, and become so large that they no longer blow up from the perforated plate.However, due to the stirring motion of the stirring device, the material to be dried is dispersed and blown up by the hot air. , forming a fluidized bed. The material to be dried that has formed this fluidized bed mixes violently with the hot air, causing water to evaporate from its surface.

Therefore, even if the material to be dried has a relatively high moisture content and tends to adhere, or is somewhat sticky,
It is possible to fluidize and dry without caking each other, resulting in a product with uniform particle size and high drying efficiency.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an outline of the fluidized bed dryer of the present invention.

[Fig. 2] Cross-sectional view taken along line II-II in Fig. 1

[Figure 3] Flow sheet diagram of a drying device incorporating the fluidized bed dryer of the present invention

[Explanation of symbols]

1──Fluidized bed dryer 2──Perforated plate 3──Drying room 4──Wind box 5──Dryer body 6─ Stirring device d──Dried material

Claims (1)

[Claims] [Claim 1] The inside of the room is partitioned approximately horizontally with a perforated plate,
The upper part is a drying chamber and the lower part is a wind box. Hot air is blown from the wind box into the drying chamber through the holes in the perforated plate, and the material to be dried is put into the drying chamber to form a fluidized bed. A fluidized bed dryer for drying dried materials is characterized in that a stirring device that makes one cycle of reciprocating motion in 1 to 300 seconds is installed in the drying chamber to assist in dispersing and floating the materials to be dried in the initial stage of drying. Fluidized bed dryer.