JPH0144374B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stirring device used for mixing and stirring powder and granular materials, solid-gas reactions, solid-solid reactions, solid decomposition reactions, and the production of granular polymers.

Equipment for this purpose generally requires a high mixing speed between the powders and granules, good contact between the gas or liquid substance and the powders,
Various performances are required, such as a large heat transfer capacity (heat transfer area x heat transfer coefficient) of the powder and a high rate of separation of generated gas and steam from the powder. BACKGROUND OF THE INVENTION Fluidized bed devices (hereinafter simply referred to as fluidized beds) for fluidizing powder and granular materials are widely used.

However, fluidized beds require the injection or circulation of a large amount of gas, which not only requires a large-capacity compressor, its power, and a device to remove fines accompanying the gas, but also requires a large amount of gas for fluidization. It cannot be applied to reactions that dislike blowing.

For this fluidized bed, an apparatus (hereinafter simply referred to as a stirred fluidized bed) that forms a fluidized state substantially similar to that of a fluidized bed by only mechanical stirring and has similar characteristics as a fluidized bed (hereinafter simply referred to as a stirred fluidized bed. For example, No. 157605 and No. 57-
Publication No. 73011, Rapid Dryer,
FORBERG instant mixer) is known. In a stirred fluidized bed, when a conductive heat exchange member is inserted into the bed, the shape and arrangement of the heat exchange member significantly affects the flow, so contact between the heat exchange member and the fine particles is preferable. Also, to make the state
In the case of highly adhesive powder or granules, the shape and arrangement of the heat exchange member are subject to significant restrictions in order to forcibly scrape off the powder adhering to the surface of the heat exchange member.

As a conductive heat exchange member to be inserted into an agitated fluidized bed, thin tubes configured in a loop shape such as a U-shape, a V-shape, or a spiral shape are conventionally known (as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 1983-1999). 73011), but as a result of study, the present inventors found that a configuration in which a disc-shaped member is connected to a rotating shaft in the form of a bead is suitable. Conventionally, such a hollow disk-shaped heat exchange member through which a heat exchange medium flows has been used in agitation devices for powder and granular materials for purposes such as drying.
It is known to rotate at a relatively low speed (for example, Tsukishima Kikai rotary desk groove type dryer, Tamagawa Kikai disk dryer, Hosokawa Micron Torrance disk dryer, Nara Kikai paddle dryer). However, these stirring devices use paddle-shaped stirring blades provided on the outer periphery of a disc-shaped member for heat exchange to flow the powder and granular material, but in all cases, the width of the stirring blade is narrow. Even if the rotational speed is increased, it is not possible to obtain the intense fluidization of powder and granules as in an agitated fluidized bed, and as a result, the mixing speed of powder and granules and the efficiency of heat exchange are severely limited. There is a problem that powder particles tend to adhere to the surface.

Generally, when powder or granules adhere to a heat exchange member as mentioned above, the attached powder or granules can be removed by attaching a fixed scraper separately or by bringing biaxially rotating heat exchange members close to each other. However, if the former scraper is installed separately, the scraper will obstruct the flow of the powder, so the latter two rotating members should be placed close together and scraped together. The structure is good.

Stirring devices with a structure that mutually scrape off deposits in this way are used in so-called self-cleaning reactors (for example, Japanese Patent Publication No. 50-21514, Japanese Patent Publication No. 46-20430), which are used as reactors for highly viscous substances. , Special Publication No. 1978-32185, Japanese Patent Publication No. 50-37888, Special Publication No. 1972
-24672), but all of these devices aim to forcefully apply shearing force to highly viscous substances to promote surface renewal.
Although each device has been devised, it is not suitable as a reactor for powder or granular materials.

The present invention provides a powder stirring device that solves the above problems at once.

According to the present invention, the disk-shaped members, which are provided in parallel and penetrating the side wall of the container of the plurality of rotating shafts and through which a heating or cooling medium flows, are attached alternately to the respective rotating shafts, Adjacent disc-shaped members are arranged with parts of them overlapping each other, and on the outer periphery of the disc-shaped member, flat stirring blades having protruding pieces at both end portions move the protruding pieces in the direction of the rotation axis. The protruding pieces are attached so as to be close to the side walls of the adjacent disc-shaped members at the overlapping part of the disc-shaped members, and the lower part of the container is composed of a partial cylinder along the locus of the tip of the stirring blade. and
There is provided a powder stirring device characterized in that the upper part of the container is formed in an arc shape.

The stirring device of the present invention has the following features.

By rotating the two-axis stirring blade at high speed, for example in the direction shown in Figure 2, the powder and granules rise along both side walls parallel to the rotation axis of the container, and violently collide and merge in the center of the container. This forms an agitated fluidized bed exhibiting a descending flow pattern (hereinafter referred to as forced circulation flow). This agitated fluidized bed has characteristics comparable to conventional fluidized beds, and in particular, the heat transfer rate between the powder and the disk-shaped member for heat exchange is high.
In addition, since the mixing and agitation of the powder and granules is good, for example, the liquid added as a reactant as needed is quickly dispersed, and there is little temperature unevenness in the powder and granules, so there is no occurrence of so-called local overheating or dead spaces. can be avoided, the throughput is large, and a homogeneous product can be obtained.

The heat exchange member is disc-shaped, and the stirring blade and the disc-shaped member are rotated in close proximity to each other to scrape off powder and granules adhering to the disc-shaped member (so-called self-cleaning structure). Since it is constructed of a partial cylinder, it can be equipped with a scraper if necessary, so it has a structure that can forcibly scrape off adhering particles over most of the heat transfer surface. Therefore, it is possible to process powder and granular materials with large adhesion and viscosity.

The forced circulation flow of powder and granules is extremely stable, and the controllable range can be controlled by the hold-up of the powder in the container and the physical properties of the powder, such as particle size, wetness, and viscosity. is wide.

Next, the present invention will be explained based on drawings showing one embodiment thereof.

A jacket 2 is attached to the container 1 to allow a heating or cooling medium to flow therethrough as required. Two rotating shafts 3a and 3b are provided in parallel and passing through both side walls of the container 1. Rotating shaft 3a, 3
b is supported by a bearing 4. Rotating shafts 3a, 3b
It is preferable that the trajectories (rotational circles) of the tips of stirring blades 5a and 5b, which will be described later, be close to the other rotating shafts 3a and 3b. Although three or more rotating shafts can be provided, there is no significant difference in stirring performance, so two shafts are practically sufficient.

Disc-shaped members 6a, 6b through which a heating or cooling medium flows are alternately attached to the rotating shafts 3a, 3b. The disk-shaped members 6a and 6b are arranged with some of them overlapping each other. The interiors of the rotating shafts 3a, 3b and the disc-shaped members 6a, 6b are structured such that a heating or cooling medium flows therethrough, as shown in FIG. 4, for example. Rotating shaft 3a,
A heating or cooling medium is connected to one end of the rotating shaft 3b.
A rotary joint 17 is attached for supplying and discharging to and from the disc-shaped members 6a and 6b. The size and number of the disc-shaped members 6a, 6b can be appropriately determined by those skilled in the art, taking into consideration the amount of heat to be heated or removed.

On the outermost periphery of the disk-shaped members 6a, 6b, flat stirring blades 5a, 5 having protruding pieces 7a, 7b at both end portions are provided.
b is attached with the protruding pieces 7a, 7b facing the rotating shafts 3a, 3b. Moreover, the protruding pieces 7a, 7b
are provided so as to be close to the side walls of the adjacent disc-shaped members 6a and 6b. That is, the protruding piece 7
a is close to the side wall of the disc-shaped member 6b, and the protruding piece 7b
is provided close to the side wall of the disc-shaped member 6a.
The flat stirring blades 5a, 5b usually have rotation shafts 3a,
3b, but in order to promote the movement of the powder in the direction of the rotation axes 3a and 3b within the container 1, it may be tilted in the axial direction or a parallel blade and an inclined blade may be combined. can. The number of the stirring blades 5a, 5b and the relative dimensions in the radial direction of the stirring blades 5a, 5b and the disc-shaped members 6a, 6b are as follows: , 6a is maximized, and both stirring blades 5a, 5b and the disc-shaped member 6 are
b and 6a are appropriately determined so that contact does not occur due to rotation.

The lower part of the container 1 is constituted by a partial cylinder along the locus of the tips of the stirring blades 5a, 5b. It consists of a partial cylinder. The limit for partial cylinders is up to 1/2 cylinder. The smaller the gap between the lower part of the container 1 and the tips of the stirring blades 5a and 5b, the better, and is generally 10 mm.
It is as follows.

The upper part of the container 1 is formed into an arc shape. In particular, it is preferable that the upper part of the container 1 is constituted by a partial cylinder whose diameter is the distance between the container walls on a horizontal line passing through the centers of the rotating shafts 3a and 3b.

A weir 8 is provided on one side wall of the container 1, and a powder extraction nozzle 9 is provided in communication with the weir 8. Note that the powder extracting device is not limited to the one shown in the figure, and for example, a
An extraction nozzle passing through the jacket 2 can also be provided.

The length of the container 1 in the axial direction is arbitrary, but it is usually 1 to 7 times the diameter of the rotation circle of the stirring blades 5a and 5b, especially
1.5 to 5 times is appropriate. The container 1 is preferably installed horizontally, but for the purpose of promoting the movement of the powder in the axial direction, it can also be installed at an angle of no more than 10° from the horizontal.

Next, a method of operating the stirring device of the present invention will be explained using formaldehyde polymerization as an example.

Gaseous formaldehyde and a known polymerization catalyst are introduced into vessel 1 from nozzles 10 and 11, respectively.
supplied to If necessary, a comonomer is supplied to the container 1 from a nozzle (not shown).

The rotating shafts 3a, 3b are rotated at a constant speed by a drive device (not shown). The rotating shafts 3a and 3b may be rotated in any direction, but from the viewpoint of uniformity of stirring, it is preferable to rotate both shafts in opposite directions. In FIG. It is particularly preferred to rotate 3b counterclockwise. The rotational speed of the rotating shafts 3a and 3b is determined by the rotational speed of the stirring blades 5.
The tip speed of a and 5b is preferably 1 to 5 m/sec.

The amount of formaldehyde polymer in the container 1 may be any amount as long as a sufficient stirring effect can be obtained.
With the stirring blades 5a and 5b stopped, the stirring blade 5
It is preferable that the amount is less than or equal to the position near the highest point drawn by a and 5b.

In the container 1, the formaldehyde polymer is stirred up by stirring blades 5a and 5b, forming a forced circulation flow.

The polymerization reaction heat is supplied to the jacket 2 from the nozzle 12, and the cooling medium is discharged from the nozzle 13.
The cooling medium is supplied from the nozzle 14 to the disc-shaped members 6a, 6b via the rotating shafts 3a, 3b, and is removed by the cooling medium discharged from the nozzle 15. In the present invention, the formaldehyde polymer violently collides with the entire disk-shaped members 6a and 6b, and the heat transfer surface itself rotates, so that the sliding force of the powder increases and the heat transfer surface is uniformly flowed. contact with animals; For this reason, there is less formaldehyde polymer adhesion to the heat transfer surface, the heat transfer surface can be easily updated, and the heat transfer coefficient can be increased by disturbing the interface, making it possible to effectively remove polymerization heat. be.

The produced polymer is extracted from the nozzle 9.
Unreacted gas is exhausted from the nozzle 16.

The case where the stirring device of the present invention is used as a polymerization reactor has been described above, but the stirring device of the present invention can also be used for thermal decomposition reactions of powdery solid materials. In this case, since the particulate solid material forms an agitated fluidized bed, the gaseous material produced in the thermal decomposition reaction can be easily moved, and the movement of this material can be prevented from limiting the reaction rate. In addition, this device has a large amount of heat transfer per unit volume (heat transfer area x heat transfer coefficient), and it is easy to supply the amount of heat necessary for the thermal decomposition reaction.Furthermore, the stirring and mixing are good, so the device is The amount of reaction per unit volume is high, and the reaction within the apparatus can be made uniform.

Furthermore, the stirring device of the present invention can mix grains, agricultural chemicals, cement, synthetic resins, etc. with various additive substances,
Drying of pulverized coal, crystalline ammonium sulfate, various synthetic resins, etc.
Gas phase polymerization of olefin, etc. can be used,
In addition to this, there are also mixers for uniformly mixing two or more types of powder or granular materials, reactions between gaseous substances and powdered solid materials, reactions between different types of powdered solid materials, and decomposition reactions of powdered or granular solid materials. , it can be used as a reactor in the production of powdery polymers.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a cross section parallel to the rotation axis of the stirring device of the present invention, FIG. 2 is a schematic diagram corresponding to the A-A cross section of FIG. 1, and FIG. FIG. 4 is a schematic partial plan view showing an example of the relative positional relationship between the stirring blade and the rotating shaft, and the shape of the stirring blade, and FIG. 4 is a sectional view showing an example of the structure of the disc-shaped member. 1... Container, 3a, 3b... Rotating shaft, 5a, 5
b... Stirring blade, 6a, 6b... Disk-shaped member, 7
a, 7b...Protruding piece.

Claims (1)

[Claims] 1 A plurality of rotating shafts are provided in parallel through the side wall of the container, and disc-shaped members through which a heating or cooling medium flows are attached alternately to each rotating shaft, and adjacent disc-shaped members are arranged with parts of them overlapping each other, and flat stirring blades having protruding pieces at both ends are placed on the outer periphery of the disc-shaped member, with the protruding pieces oriented in the direction of the rotation axis, and the disc-shaped The protruding pieces are attached so as to be close to the side walls of adjacent disc-shaped members at the overlapping part of the members, and the lower part of the container is composed of a partial cylinder that follows the trajectory of the tip of the stirring blade, and the lower part of the container is A stirring device for powder and granular material characterized by an upper part formed in an arc shape.