JPH01111190A - Fluidized bed drier - Google Patents

Abstract

PURPOSE: To achieve a pre-drying and a main drying continuously with one drying device by a method wherein a re-drying chamber with a draft plate on a bottom part thereof is successively arranged on one side of a drying chamber through an overflow weir and a dumping port for matters to be dried is provided at an upper part thereof to link a lower part of the draft plate to a low temperature hot air source from a hot air source to be applied to a drying chamber. CONSTITUTION: Matters to be dried comprising granular solid material containing crystal water is fed into a pre-drying chamber 6 from dumping port 2 while hot air is sent into the re-drying chamber 6 through the draft plate 9 from a low heat source. The granular solid material in the pre-drying chamber 6 is fluidized to promote drying. The granular solid material dried to a certain extent is moved to a drying chamber 5 beyond an overflow weir 4. On the other hand, hot air is sent into the drying chamber 5 through the draft plate 9 from a high heat source while a rotating shaft 15 is rotated to send steam to a hollow part from a steam pressure source to heat the rotating shaft 15 and a heating tube 16. Thus, the granular solid material is moved in the direction of an exhaust port 3 being agitated by the heating tube 16 to dry not only the granular solid material with a small diameter but also that with a large diameter and the lightened granular solid material is taken out from the exhaust port 3 beyond a partition 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fluidized bed drying apparatus having a built-in heating tube. The present invention relates to a fluidized bed drying apparatus which is particularly useful for application.

[Prior Art] A fluidized bed drying device with a built-in heating tube has a drying chamber configured with a ventilation plate at the bottom, and a heating tube rotatably disposed inside the drying chamber so that the heating tube extends from below the ventilation plate toward the drying chamber. A heating medium is supplied to the heating tube at the same time as hot air is blown, and the material to be dried in the drying chamber is brought into a fluidized state so that large-diameter particles contained therein can be dried as efficiently as small-diameter particles. It is.

As such a drying device, for example, Japanese Patent Application Laid-Open No. 81-3986 filed by the applicant of the present invention and Japanese Patent Application Laid-open No. 61
The invention disclosed in Japanese Patent No. 3987 is well known.

In the former invention, the drying chamber of a horizontal fluidized bed dryer is provided with one or more rotating shafts to which heating tubes with spiral feeding blades are attached on the outer periphery, and the bottom surface of the drying chamber is A ventilation plate stretched over the air is formed into a gutter-like shape, and the feed blade has the function of a transfer screw.The small-diameter particles of the material to be dried in a fluid state are dried under normal conditions, and the large-diameter particles are dried under normal conditions. The particles are dried by moving them inside the drying chamber at an appropriate speed. This allows large-sized particles to be dried to the same extent as small-sized particles without reducing drying efficiency.

In addition, in the latter invention, a rotating shaft connected to a heating tube is erected in the center of the bottom plate of the drying chamber to serve as a heat medium supply/discharge pipe, and its lower part is placed close to the bottom plate to connect with the stirring blade near the top surface of the bottom plate. In addition to increasing the apparent amount of heat supplied per unit area to increase drying efficiency, the entire device is downsized to reduce equipment costs, and the agitation function of the fluidized bed is utilized to improve drying efficiency. It is designed to improve the

[Problems to be Solved by the Invention] The fluidized bed drying device with a built-in heating tube as described above has many features and has been well received among users.
For example, there is a problem when drying a material containing water of crystallization, such as an organic acid salt. In other words, when such materials to be dried are dried, the surfaces of these materials are dissolved by their own evaporated water due to heating, and as a result, powders and granules may bond with each other or adhere to the surface of the metal that constitutes the drying equipment. Not only did this reduce drying efficiency, but it also sometimes became inoperable. For this reason, the operation had to be stopped from time to time to clean the inside of the drying chamber.

By the way, if the material to be dried containing such water of crystallization is pre-dried (or aged) at a lower temperature before being blown with high-temperature hot air in the drying room and then put into the drying room, the powder and granules will be mixed with each other. Since bonding and adhesion to metal surfaces can be prevented, conventionally a pre-drying device is provided separately from the drying device, and the material to be dried is first pre-dried at a relatively low temperature by the pre-drying device, and then the material discharged from the drying device is pre-dried at a relatively low temperature. The dried material was put into a drying device with a built-in heater for drying.

For this reason, two drying devices must be installed, which not only requires a large space but also increases equipment costs, and the material to be dried that has been heated in the pre-drying device must be taken outside. Therefore, continuous operation was difficult, and there were various problems such as large heat loss.

[Object of the invention] In order to solve the above-mentioned problems, the present invention provides a fluidized bed drying device equipped with a built-in heater that can perform pre-drying and main drying continuously with one drying device. The purpose is to

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a drying chamber having a ventilation plate at the bottom and a heating tube rotatably disposed above the ventilation plate. In the apparatus for blowing hot air into the drying chamber through the ventilation plate and causing the material to be dried in the drying chamber to flow and dry by the hot air and heating tube, an overflow weir is provided on one side of the drying chamber. A pre-drying chamber is provided with a ventilation plate at the bottom of the pre-drying chamber, an inlet for the material to be dried is provided at the upper part of the pre-drying chamber, and the lower part of the ventilation plate is connected to the hot air at a lower temperature than the hot air source which is applied to the drying chamber. A fluidized bed dryer connected to a source is provided.

[Operation] The material to be dried, which is introduced into the pre-drying chamber through the input port, is fluidized and dried with hot air at a relatively low temperature, and when drying has progressed to a certain extent, it is sent over the overflow weir to the drying chamber. In the drying room, high-temperature hot air is applied to fluidize the material to be dried, and
The material is moved and dried while being heated by a heating tube, and the dried material is taken out from the discharge port.

Embodiment of the Invention FIG. 1 is a schematic diagram of an embodiment of the invention. In the figure, 1
2 is a drying device, 2 is an input port for the material to be dried (powder or granular material), and 3 is a discharge port. Reference numeral 4 denotes an overflow weir installed below the input port 2, which divides the interior of the drying device 1 into a drying chamber 5 and a pre-drying chamber 6, and a tubular portion 7 is formed between it and the outer wall. There is.

8 is installed on the opposite side of the overflow weir 4, and the drying chamber 5
This is a partition wall that partitions the discharge port 3 and the discharge port 3. Reference numeral 9 denotes a ventilation plate provided at the lower part of the drying chamber 5 and the pre-drying chamber 6, and is provided with a large number of ventilation holes 10. 11 is a first chamber provided at the bottom of the drying chamber 5; 12 is a second chamber provided at the bottom of the pre-drying chamber 6; In addition, the second chambers 12 are each connected to a lower temperature heat source (not shown) via an air blower. Therefore, when hot air is sent from both heat sources to the first and second chambers 11.12 by a blower, the hot air passes from the ventilation hole 1o of the ventilation plate 9 through the drying chamber 5 and the pre-drying chamber 6, and then exits from the exhaust port 13. is discharged to.

14 is a heating tube assembly, in which a heating tube 1B made of, for example, a thin pipe is spirally arranged in a part of the hollow rotating shaft 15 (within a range corresponding to the length between the overflow weir 4 and the partition wall 8). , both ends of which are connected to the hollow part of the rotating shaft 15. Rotating shaft 1 of this heating tube assembly 14
One end of the heating tube 5 projects outward from the tubular portion 7 above the ventilation plate 9, and the other end projects outward through the partition wall 8 and the outer wall. It is supported by the tubular part 7 and the bearing 17. Note that a bearing may also be provided on the tubular portion 7 side. One end of the rotating shaft 15 (left side in the figure) is connected to a steam pressure source (not shown) via a rotary joint and a control valve.
When the control valve is opened, high-temperature steam is sent into the hollow part of the rotating shaft 15, passes through the hollow part and inside the heating pipe 16, and is discharged from the other end.

Reference numeral 18 denotes an air chamber provided on the outer wall of the drying device 1, which opens into a gap g formed between the inner wall of the tubular portion 7 and the outer periphery of the rotating shaft 15, and is connected to an air pressure source (not shown) via a control valve. ing. A gear 19 is fixed to the rotating shaft 15, and is connected to the output gear 20 of the motor 21 either directly or via an intermediate gear or the like.

Next, the present invention configured as described above will be explained in detail. First, the material to be dried consisting of powder and granules containing crystal water is introduced into the pre-drying chamber 6 from the input port 2, and the ventilation plate 9 is introduced from a low heat source.
Hot air (90° C. in the example) is sent into the pre-drying chamber 6 through the drying chamber 6. As a result, the powder and granules in the pre-drying chamber 6 flow and drying is promoted, and the partially dried powder and granules move over the overflow weir 4 to the drying chamber 5.

On the other hand, hot air (150° C. in the example) is sent from the high heat source into the drying chamber 5 through the ventilation plate 9, and at the same time, the rotating shaft 15 is rotated to supply steam (150° C. in the example) to the hollow part from the vapor pressure source.
°C) to heat the rotating shaft 15 and heating tube 16. As a result, the powder and granules move in the direction of the discharge port 3 while being stirred by the heating tube 1B, and not only the small diameter granules but also the large diameter granules are completely dried, and the lightened powder and granules are transferred to the partition wall 8. is taken out from the discharge port 3.

At this time, if high-pressure air is blown from an air pressure source through the air chamber 18 into the gap g formed between the tubular part 7 and the rotating shaft 15 for purging, there is a risk that powder and granules from the drying chamber 5 will enter this gap g. There is no. Furthermore, since the rotating shaft 15 is disposed within the tubular portion 7 with the gap g interposed therebetween, even if high-temperature steam is supplied to the rotating shaft 15, there is no fear that the heat will increase the temperature of the pre-drying chamber 6. The material to be dried is then heated and dried to a certain degree in the pre-drying chamber 6 and sent to the drying chamber 5.
There is no possibility that the powder particles will combine with each other or adhere to the surface of the heating device.

FIG. 2 is a schematic diagram of another embodiment of the present invention, in which the same or equivalent parts as in the embodiment of FIG. This embodiment uses a heating tube assembly 14 having a structure different from that of the embodiment shown in FIG. A heating tube 16 having a heating tube 16 is arranged concentrically with the rotating shaft 15, one end of which is connected to the hollow part of the rotating shaft I5, and the other end supported by a stay L5a. This heating tube assembly 14 is rotatably supported at both ends by bearings 17.17a between the overflow weir 4 and the outer wall, and the open end is connected to a high temperature heat source (not shown) via a blower.
The heating tube 16 is located inside the drying chamber 5.

The operation of this embodiment configured as described above is similar to that of the embodiment shown in FIG. 1, but the heating tube assembly 14
Hot air at a high temperature (for example, 150° C.) is applied from a heat source to the rotating shaft 15 of the rotary shaft 15 to heat the rotating shaft 15 and the heating tube 16 and discharged into the drying chamber 5 from the small hole 8a. In this case, since hot air is applied to the drying chamber 5 from both the lower part and the small hole 1 [ia of the heating tube 16], the powder and granules are scattered inside the drying chamber 5 and are discharged from the exhaust port 13. It is also possible, but
In this case, both wind speeds may be appropriately controlled.

In the above explanation, the heating tube assembly 4 has been shown in which the heating tubes 16 are arranged in a spiral or pincushion shape around the rotating shaft 15, but it goes without saying that other structures may also be used. do not have. Furthermore, in the embodiment shown in FIG. 1, a case is shown in which high-pressure air is blown out from the air chamber 18 to prevent the material to be dried from leaking out from the gap g formed between the tubular portion 7 and the rotating shaft 15. This gap g can be reduced by providing a bearing in the tubular part 7, etc.
If it is sealed, air blowing can be omitted.

Using the fluidized bed drying apparatus shown in FIG. 1, the material to be dried consisting of lysine acid salt was placed into the pre-drying chamber 6 at a layer height of 200 mm, and was blown into the pre-drying chamber 6 from the second chamber 12 at a temperature of 90 mm. After pre-drying the material to be dried from 18% WB to 14 to 15% νB by applying hot air at 1.5 m/s for 5 minutes at a temperature of 1.5 m/s, the material is dried in the drying chamber 5 in which the heating tube 1B is heated to 150°C. When this was carried out, there was no bonding between the particles or adhesion to the metal surface of the heating tube 16, etc., and the material to be dried could be dried in a good condition.

[Effects of the Invention] As is clear from the above description, according to the present invention, the following remarkable effects can be obtained.

(1) Since preliminary drying and main drying can be performed with one drying device, not only the device can be made smaller and the installation space can be reduced, but also the equipment cost can be reduced.

(2) Pre-drying and main drying are performed in one drying device, allowing continuous operation and reducing heat loss.

(3) Since the preliminary drying is followed by the main drying, a high-quality product can be obtained without the powder particles bonding with each other or adhering to the metal surface of the device. As a result, there is no need to stop the operation from time to time to clean the inside of the dryer, which not only greatly improves the operating rate of the dryer, but also
The work efficiency of the entire factory can be improved.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams of embodiments of the present invention, respectively. 1: Drying device, 2. Input port, 3: Outlet port, 4 Nibarflow salt, 5: Drying room, 6: Pre-drying room, = 11
- 7: tubular part, 9: ventilation plate, 11 2 first chamber, 12
: second chamber, 14: heating tube assembly, 15:
Rotating shaft, I6: heating tube.

Claims (1)

[Claims] A drying chamber is provided with a ventilation plate at the bottom and a heating tube rotatably disposed above the ventilation plate, and hot air is blown into the drying chamber through the ventilation plate. , an apparatus for drying the material to be dried in the drying chamber by flowing it with hot air and heating tubes, wherein a pre-drying chamber equipped with a ventilation plate at the bottom is connected to one side of the drying chamber via an overflow weir. A fluidized bed drying apparatus, characterized in that an input port for the material to be dried is provided in the upper part of the pre-drying chamber, and the lower part of the ventilation plate is connected to a hot air source having a lower temperature than the hot air source applied to the drying chamber.