JP4584737B2 - Evaporative stirring tank operation method - Google Patents

Description

The present invention relates to a method for operating an evaporative stirring tank in which a solution is stirred in a heated state.

Conventionally, liquid materials such as slurries and solutions are stored in a tank and stirred in a heated state to evaporate liquid media contained in the slurry and solutions such as water and organic solvents, thereby concentrating these liquid materials. An evaporative stirring tank is used in which is carried out by batch processing.
As such an evaporative stirring tank, Patent Document 1 discloses a stirrer provided with a bowl-shaped cylindrical tank body, a stirring blade that is arranged only at the bottom of the stirring tank and rotates in the horizontal direction, and a baffle; It is described that the solution is concentrated using the stirring device.
In addition, usually, the tank body of such an evaporating and stirring tank is provided with a mantle portion so that the tank wall has a substantially double structure, and a heating medium is circulated through the double structure part to form the inner wall of the tank. Is heated, and the liquid material inside the tank is heated by heat transfer from the inner wall surface of the tank.
Therefore, in such an evaporative stirring tank, for example, the concentration of the liquid material proceeds and the amount of liquid decreases, the contact area between the inner wall surface of the tank and the liquid material decreases, and the liquid medium is not efficiently evaporated, There is a problem that the operating efficiency is lowered.

In response to such a problem, by increasing the rotation speed of the stirring blade, the flow rate of the entrained flow in which the liquid material flows in the same direction as the rotation of the stirring blade is increased, and the liquid level of the liquid material on the inner wall surface of the tank is increased. It can be considered that the contact area between the inner wall surface of the tank and the liquid material is reduced, but in such an evaporative stirring tank, the flow rate of the entrained flow is reduced by the baffle described above. It is difficult to suppress a decrease in contact area between the inner wall surface of the tank and the liquid material.
In addition, it can be considered that the evaporative stirring tank is not provided with a baffle. However, in this case, the stirring performance of the liquid material is lowered, and the operation efficiency may be lowered.

  That is, the conventional evaporation stirring tank has a problem that it is difficult to suppress a decrease in the contact area between the inner wall surface of the tank and the liquid material while suppressing a decrease in stirring performance.

JP 2003-33635 A

  This invention is made | formed in view of the above-mentioned problem, and makes it a subject to suppress that the contact area of a tank inner wall surface and a liquid substance reduces, suppressing the fall of stirring performance.

  Even when the present invention uses a stirring blade disposed only at the bottom, by forming the shape of the inner surface of the tank body into an inverted conical shape, the formation of an upward flow of the liquid material is promoted and the stirring performance is improved. The inventors have found that it can be improved and have completed the present invention.

That is, the present invention is an operation method of an evaporative stirring tank in which a liquid substance is stirred in a heated state and the liquid substance is concentrated by evaporating a liquid medium in order to solve the above-described problem. The tank has an inner surface formed in an inverted conical shape and accommodates the liquid material, and a stirring blade that is disposed only at the bottom of the tank body and rotates in the horizontal direction to flow the liquid material in the rotation direction. It is provided, after reduction liquid material by evaporation of the liquid medium, provides a method of operating a vaporization stirred tank, characterized in that to increase the rotational speed of the stirring blade than prior liquid material loss.

According to the present invention, since the shape of the inner surface of the tank body is an inverted conical shape, the stirring performance can be improved without providing a baffle or the like in the tank. Further, the liquid level of the liquid material on the inner wall surface of the tank can be increased, and the contact area between the inner wall surface of the tank and the liquid material can be suppressed from decreasing.
That is, it can suppress that the contact area of a tank inner wall surface and a liquid substance reduces, suppressing the fall of stirring performance.

Hereinafter, a preferred embodiment of the present invention will be described by taking the evaporation stirring tank shown in FIGS. 1 and 2 as an example.
The evaporative stirring tank 1 in this embodiment has a tank body 2 and an agitating mechanism 3 that have an inner surface formed in an inverted conical shape and accommodates a liquid material. The agitating mechanism 3 is disposed only at the bottom of the tank body 2. In addition, a stirring blade 31 that rotates in the horizontal direction and causes the liquid material to flow in the rotation direction is provided.
Further, the evaporative stirring tank 1 is not provided with a mechanism for disturbing the entrained flow in which a liquid substance such as a baffle flows in the rotation direction of the stirring blade.

The tank body 2 has a region substantially equivalent to a portion in contact with the liquid material in the stirring state when the liquid material having the maximum stirring capacity is stirred so that the liquid material can be heated by heat transfer from the inner surface thereof. The outer wall 21 is formed so that the tank wall has a double structure, and the inner wall of the inverted conical shape is formed up to a portion further above the outer wall 21.
The inverted conical shape is formed so as to have an apex angle of 30 degrees.

  A discharge port 25 for concentrating and discharging the liquid material is provided at the bottom of the tank body 2, and a temperature measuring body 22 for measuring the internal temperature is attached.

The stirring mechanism 3 includes a stirring shaft 32 provided along the central axis direction of the tank body, and a drive motor 34 and a speed reducer 35 that are connected to the upper end portion of the stirring shaft 32 and rotate the stirring shaft. A stirring blade 31 that rotates together with the stirring shaft 32 is attached to the lower end portion of the stirring shaft 32. The stirring blade 31 is formed of a horizontally long plate-like member, and is attached to the stirring shaft 32 so that the plate surface of the horizontally long plate-like member faces perpendicularly to the rotation direction.
The stirring blade 31 is a retreating blade that retreats in the rotation direction, and a bent portion 31a is formed at the outer end portion thereof.
Moreover, this retreating blade is formed so that a lower end part follows the bottom face shape of the said stirring tank. Furthermore, the corners of the plate member are all chamfered.
Further, the stirring blade 31 is arranged so as to be close to the bottom of the tank body so that the liquid can be stirred even when the liquid in the tank body 2 is concentrated and the liquid amount is further reduced.

Next, an operation method using such an evaporation stirring tank 1 will be described.
First, a predetermined amount of liquid material is accommodated in the tank body 2 and stirred by the stirring blade 31. At this time, a heating medium having a predetermined temperature is introduced from the heat medium inlet 23 to fill the outer portion 21 with the heating medium, and the liquid material is brought to a predetermined temperature by heat transfer from the inner surface of the tank body. After that, the heat of the heating medium is used as heating of the liquid material in the tank or as latent heat of evaporation for evaporating the liquid medium of the liquid material, and the temperature of the heating medium is lowered. While discharging from the heat medium outlet 24, a new heating medium is caused to flow from the heat medium inlet 23, thereby maintaining the liquid material at a predetermined temperature.

  At this time, the stirring blade 31 causes the liquid material to flow in the rotation direction, and moves the liquid material outward from the center of the tank while flowing the liquid material in the rotation direction by a centrifugal force accompanying the rotation. As a result, the liquid level of the liquid material changes from a horizontal state A at rest to a state B where the liquid level at the wall surface is higher than the center of the tank, and the contact area with the inner surface of the tank wall increases, resulting in a liquid medium Evaporation is promoted. At this time, since the inner surface of the tank wall is formed in an inverted conical shape as described above, the force that the liquid material tries to move outward by centrifugal force is transferred to the upward flow that moves upward along the inner surface of the tank. It can be converted, and the stirring performance can be made superior to that of a conventional cylindrical stirring tank.

  Thereafter, when the liquid medium evaporates and the concentration of the liquid material proceeds, the liquid level (arrival position) of the liquid material on the inner surface of the tank decreases. However, the tank wall of this embodiment has an inner surface formed in an inverted conical shape, so that the liquid level accompanying the decrease in the liquid volume is lower than that of the conventional cylindrical stirring tank in which the liquid level decreases in proportion to the decrease in the liquid volume. The lowering of the surface arrival position can be made gradual, and the arrival position is less than the upper end position of the mantle portion 21 while suppressing a decrease in the contact area (heat transfer area) between the inner surface of the tank body and the liquid material. It is possible to prevent scales from being generated due to the occurrence of high temperature spots on the inner surface of the tank.

  Further, even when the concentration of the liquid material further proceeds, the stirring blade of the present embodiment is not provided with a mechanism for disturbing the accompanying flow such as a baffle provided in the cylindrical evaporation stirring tank. It is easy to increase the flow velocity at which the liquid material flows in the direction of rotation of the stirring blade 31 by increasing the rotation speed of the 31, and it is possible to prevent the arrival position of the liquid material from being lowered below the heating portion by the mantle portion 21. It is possible to more effectively prevent the occurrence of scale and the like while suppressing the reduction of the thermal area.

  Finally, when the concentration of the liquid material is completed, the discharge port 25 is opened and the liquid material is allowed to flow down and discharged. At this time, no baffle or the like is provided in the tank, and since no wings are used throughout the tank, such as a helical ribbon wing, liquid products are prevented from adhering to the product. The yield of (concentrated liquid) can be made high.

  Further, since no baffle or the like is provided, and no blades such as a helical ribbon blade are disposed throughout the tank, cleaning is easy and maintenance is easy.

In addition, as the heating medium used for such operation, various fluids such as hot water, steam, and oil can be used according to the purpose. Simple fluid conveying means can be used.
Further, the liquid material to be concentrated is not particularly limited, but is a low-viscosity liquid material that has high fluidity and is easy to form an entrained flow or an upward flow, for example, a viscosity when taken out as a product. Is preferably a liquid having a viscosity of 1000 mPa · s or less. Further, in this respect, a liquid material having a viscosity of 200 mPa · s or less is more preferable.

In this embodiment, by changing the temperature of the heating medium to be fluidized, it is easy to control the temperature of the tank inner surface or the liquid material, and a more efficient operation can be performed. In the present invention, the heating means for the inner surface of the tank body is not limited to the jacket part, but a method using a heating wire such as a nichrome wire or a heating means using an infrared heater or the like is used. Instead of the means for circulating the heating medium, it may be used in combination.
Furthermore, the method for heating the liquid material is not limited to heat transfer from the inner surface of the tank body.

  Further, in this embodiment, the volume per unit area of the tank body is increased, and the upward flow of the liquid material can be efficiently generated, so that the inverted cone shape of the tank body has an apex angle of 30 degrees. However, in the present invention, the inverted conical shape of the inner surface of the tank body is not limited to an apex angle of 30 degrees, and usually the apex angle is increased if it is 20 to 90 degrees. High agitation performance by flow is obtained. In addition, it is preferable that the said apex angle is 25 to 40 degree | times from the point which can generate | occur | produce the upward flow of a liquid substance efficiently, making the volume per installation area of a tank main body larger.

  Further, in the present embodiment, the inverted conical shape is formed at a position higher than the highest position where the liquid material is reached, but in the present invention, the inverted conical shape of the tank body is formed in the entire area where the liquid material contacts. It is not limited to being.

  Further, in the present embodiment, the swept blade as described above is used in that the discharge flow is high and the ability to fluidize the liquid material is excellent. The blades are not limited to swept wings, and Faudler wings (three swept wings), paddle blades, and other stirring blades may be used.

The schematic sectional drawing which shows the evaporation stirring tank of one Embodiment. X-X 'arrow sectional drawing of FIG.

Explanation of symbols

1: Evaporation stirring tank, 2: Tank main body, 3: Stirring mechanism, 21: Mantle part, 31: Stirring blade A: Liquid state at rest, B: Liquid state at stirring

Claims (3)

An operation method of an evaporation stirring tank in which a liquid material is stirred in a heated state and the liquid material is concentrated by evaporating a liquid medium,
The evaporative agitation tank has an inner surface formed in an inverted conical shape and accommodates only the liquid body and the bottom of the tank body, and rotates horizontally to flow the liquid material in the rotation direction. A method for operating an evaporative stirring tank , comprising: a stirring blade, wherein after the liquid material is reduced by evaporation of the liquid medium, the rotational speed of the stirring blade is increased more than before the liquid material is reduced . The operation method of the evaporation stirring tank according to claim 1 , wherein the evaporation stirring tank is provided with a heating means for heating the tank body so that the liquid material can be heated by heat transfer from the inner surface of the tank body. . The inverted cone shape of the evaporation agitation tank, the method operation of evaporation stirring vessel according to claim 1 or 2 Ru Tei is the apex angle 25 to 40 degrees.

Images