JPH0144373B2 - - 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.

In contrast to conventional fluidized beds (simply referred to as fluidized beds) that fluidize powder and granular material by blowing in a large amount of gas, there is a device that creates a fluidized state substantially similar to that of a fluidized bed using only mechanical stirring. , is already known as a stirred fluidized bed (for example, JP-A-55-157605 and JP-A No. 57-157-
Publication 73011, Rapid Dryer, FORBERG
instant mixer).

However, in a stirred fluidized bed, when a heat exchange member that circulates a heat medium inside as a transmission type heat exchange member is inserted into a powder bed, its shape and arrangement have a large influence on the flow, and In order to make good contact between the member and the granular material and to efficiently exchange heat between the two, there are significant restrictions on the shape and arrangement of the heat exchange member to be inserted. In addition, in the case of powder or granular materials with strong adhesion, depending on the shape and location of the heat exchange member,
It is also difficult to forcibly scrape off the powder particles adhering to the surface, and the efficiency of heat exchange decreases within a short period of time.

In the above-mentioned JP-A-55-15760 and JP-A-57-73011, two stirring shafts with stirring blades attached via support rods are installed at the bottom of the container, and a fixed cooler is attached to the container. A polymerization reactor installed at the top is described. Although this device is efficient when limited to agitation of powder and granules, when processing powder and granules with strong adhesion or viscosity, these particles adhere to the surface of the cooler. The capacity of the cooler decreases within a short period of time.

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

According to the present invention, a plurality of stirring shafts equipped with stirring blades are provided at the bottom of the container, penetrating the side wall of the container, and the bottom of the container is formed of a partial cylinder along the locus of the tips of the stirring blades. A horizontal stirring device is provided, in which a rotating shaft having a disk-shaped member attached thereto, through which a heating or cooling medium flows, is provided in the upper part of the container, passing through the side wall of the container.

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

At the bottom of the container 1, two stirring shafts 2 and 3 are provided passing through the side walls 4 and 5 of the container 1. Stirring shafts 2 and 3 are supported by bearings 6 and 7. It is preferable that the stirring shafts 2 and 3 are provided substantially horizontally and parallel to each other.
The distance between the stirring shafts 2 and 3 is determined by the locus (rotation circle) of the tip of the stirring blade 9 provided on the shaft via the support 8.
It is preferable that the two surfaces are close to each other or even overlap. Note that three or more stirring shafts may be provided, but since there is no significant difference in mixing performance, two stirring shafts are practically sufficient.

There are no particular restrictions on the shape of the stirring blades 9, but
Generally, paddle blades are used to stir up the powder in the container 1. For the purpose of stirring up the powder and granules, it is preferable to place the paddle blades parallel to the stirring shafts 2 and 3. However, in order to create a gentle circulation flow throughout the container 1, the paddle blades may be tilted or placed horizontally. It is also possible to combine blades and inclined blades.

A plurality of stirring blades 9 are mounted symmetrically on the stirring shaft. Three blades or four blades can also be used, but usually
Two blades spaced 180 degrees apart is sufficient. The spacing between the stirring blades 9 in the axial direction is also arbitrary, but from the point of view of the stirring effect, it is preferable that they be close to each other, and they are usually installed at intervals of 1.1 to 3 times the width of the blades. The relative position of the stirring blades 9 between the two shafts is such that both blades do not come into contact with each other due to rotation.

The bottom of the container 1 is formed of a partial cylinder along the trajectory of the tip of the stirring blade 9. The limit for partial cylinders is up to 1/2 cylinder. That is, when the tips of the stirring blades 9 are spaced apart from each other, a chevron-shaped connection part is provided at the bottom of the container 1 in the middle thereof to prevent the powder from stagnation. The distance between the bottom of the container 1 and the tip of the stirring blade 9 is preferably as small as possible, and is generally 10 mm or less.

The height of the container 1 is desirably greater than the height of the agitated and floated powder and granules, and is therefore at least 1.2 times the diameter of the closest rotation circle drawn by the stirring blades 9, preferably 1.5.
~3.5 times. 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, especially 1.5
~5 times is appropriate.

Inside the container 1, rotating shafts 11 and 12, each having a disk-shaped member 10 for cooling or heating attached to the top of a stirring blade 9, are provided passing through the side walls 4 and 5, and are supported by bearings 13 and 14. . Rotating shaft 11
and 12 are installed parallel to the stirring shafts 2 and 3. The rotating shafts 11 and 12 are provided so that the lower end of the disk-shaped member 10 attached to them is near the highest point of the trajectory of the stirring blade 9. The size, number, etc. of the disc-shaped member 10 can be easily determined by those skilled in the art, taking into consideration the polymerization reaction heat layer to be removed.

The insides of the disc-shaped member 10 and the rotating shafts 11 and 12 are structured so that a cooling or heating medium flows therethrough, as shown in FIG. 3, for example. A rotary joint 15 is provided at one end of the rotating shafts 11 and 12.
is attached, a cooling or heating medium is supplied to the disc-shaped member 10, and after heat exchange, is discharged through the rotating shafts 11 and 12.

Although it is not normally necessary, as shown in FIG.
8 can also be fixed to the support shaft 19.

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

Gaseous formaldehyde and catalyst are introduced into vessel 1 through tubes 16 and 17, respectively.

The stirring shafts 2 and 3 are rotated at a constant speed by a drive device (not shown). The rotation directions of the stirring shafts 2 and 3 may be arbitrary, but from the viewpoint of uniformity of stirring,
Preferably, both shafts are rotated in opposite directions. The rotational speed of the stirring blades 9 is determined in consideration of the size of the container 1, the size and number of blades, etc. In order to obtain a sufficient stirring effect, the height of the pulverized polymer in the container 1 is generally set at a height higher than that of the stirring blade 9.
A rotation speed is adopted which is approximately 0.5 to 2 times the rotational diameter of the stirring blade at the height from the upper end of the stirring blade 9. This generally corresponds to a linear velocity of 1 to 5 m/sec at the tip of the stirring blade 9.

The amount of powdery polymer in the container 1 may be any amount as long as a sufficient stirring effect can be obtained, but the amount below the highest point drawn by the stirring blade 9 when the stirring blade 9 is stopped is sufficient. It is preferable that there be.

Inside the container 1, the particulate polymer is stirred up by the stirring blades 9 to form a fluidized bed. The upper surface of this fluidized bed is preferably located above the highest point of the disc-shaped member 10 in order to effectively remove the heat of polymerization reaction.

The rotating shafts 11 and 12 are rotated by a drive device (not shown). There is no particular restriction on the direction of rotation of the rotating shafts 11 and 12. Further, there is no particular restriction on their rotational speed, but in order to increase the apparent collision speed between the powdery polymer and the disc-shaped member 10, the contact speed of the tip of the disc-shaped member is set as
Preferably, the speed is 0.3 to 3 m/sec.

The heat of polymerization reaction is removed by the wall of the container 1 and the disc-shaped member 10. In particular, in the present invention, by installing the disc-shaped member 10 in a fluidized bed generated by the violent stirring or splashing effect of the stirring blades 9, the disc-shaped member 10
The granular polymer collides violently with the whole, and the heat transfer surface itself rotates, so that the sliding force of the granule increases, and the heat transfer surface uniformly contacts the fluid. As a result, there is less adhesion of granular polymer to the heat transfer surface, the heat transfer surface can be updated easily, the heat transfer coefficient can be increased by disturbing the boundary surface, and polymerization heat can be effectively removed. It is.

The resulting polymer is withdrawn from the tube 20 in such a way as to maintain the height of the fluidized bed within the vessel 1 substantially constant and to avoid sudden changes in the pressure within the vessel 1 .

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 movement of gaseous substances generated in the thermal decomposition reaction is easy, and it is possible to avoid the movement of this gas from controlling the reaction rate. . In addition, this device has a large amount of heat transfer per unit volume (heat transfer area x heat transfer coefficient).
Since the amount of heat required for the thermal decomposition reaction is easily supplied, and furthermore, stirring and mixing are good, the amount of reaction per unit volume of the apparatus 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.
Can be used for gas phase polymerization of olefins, etc.
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 particulate polymers.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a cross section perpendicular to the stirring axis of the stirring device of the present invention, FIG. 2 is a schematic diagram corresponding to the − cross section of FIG. 1, and FIG. 3 is a portion of a disc-shaped member. FIG. 4 is a schematic cross-sectional view showing the relative relationship between the powder scraping tool and the disc-shaped member. DESCRIPTION OF SYMBOLS 1... Reactor, 2, 3... Stirring shaft, 9... Stirring blade, 11, 12... Rotating shaft, 10... Disk-shaped member.

Claims (1)

[Claims] 1 A plurality of stirring shafts equipped with stirring blades are provided at the bottom of the container, penetrating the side wall of the container, and the bottom of the container is composed of a partial cylinder that follows the trajectory of the tips of the stirring blades. 1. A stirring device for powder and granular material, characterized in that a rotating shaft having a disk-shaped member attached thereto, through which a heating or cooling medium flows, is provided in the upper part, penetrating the side wall of the container.