JP2018089558A - Crystallization reaction bath, and crystallization reaction classifier using the reaction bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystallization reacting bath having a classification function enabled to extract particles of a desired diameter or more while being enabled to perform crystallization efficiently by one agitation vessel by providing a draft tube or a housing of a cylindrical shape and a plurality of types of agitation blades in a continuous type agitation vessel, and a crystallization reaction classifier using the reacting bath.SOLUTION: A crystallization reacting bath comprises: an agitation vessel for holding a crystallization material; a rotation shaft extending vertically of the inside of the agitation vessel; a draft tube disposed to enclose a predetermined depth area around said rotation shaft; first agitation blades fixed on said rotation shaft and disposed in said draft tube; and second agitation blades fixed on said rotation shaft and disposed outside of said draft tube.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a crystallization reaction tank and a crystallization classification apparatus using the same, and in particular, in a continuous stirring tank, particles having a desired particle diameter or more are simultaneously discharged while efficiently performing a crystallization reaction in the tank. The present invention relates to a crystallization reaction tank and a crystallization classification apparatus using the same.

  Conventionally, in the crystallization reaction tank, the supplied raw material reacts, and the seeds generated separately from the nuclei generated in the supersaturated region or separately from the raw material are uniformly dispersed in the tank, and the raw material is efficiently obtained. Crystallization reaction.

  In the case of a continuous crystallization reaction tank, there are many cases where the crystallization reaction is carried out in the tank and overflowed or continuously discharged from the tank bottom (for example, see Patent Document 1 and Non-Patent Document 1).

JP 2012-210629A

SCEJ80th Annual meeting, Lecture number E114, Role of stirring and mixing in crystallization operation, Tsukishima Kikai

  However, when the reaction tank is a single tank, the time during which each crystallized particle stays in the tank is different, so that the crystallization reaction varies and the particle size distribution is generated. For this reason, when it is desired to take out particles having a desired particle size or more and make a product, it is necessary to classify the crystallized particles as a post-crystallization process in the crystallization reaction tank, and the installation cost of the classification equipment and its running There was a problem that extra costs were required.

  Therefore, the present invention provides a continuous agitation tank with a cylindrical tube and a plurality of types of agitation blades so that a desired particle size can be obtained while efficiently performing a crystallization reaction in one agitation tank. It aims at providing the crystallization reaction tank which has the classification function which can take out the above particle | grains, and the crystallization classification apparatus using the same.

In order to achieve the above object, a crystallization reaction tank according to one embodiment of the present invention includes a stirring tank for holding a crystallization raw material,
A rotating shaft extending vertically in the stirring tank;
A draft tube provided to surround a predetermined depth region around the rotation axis;
A first stirring blade fixed to the rotating shaft and provided in the draft tube;
A second agitating blade fixed to the rotating shaft and provided outside the draft tube.

  According to the present invention, a stable circulation flow can be formed in the tank, and a stable low-speed rising flow can be formed in the center of the tank bottom. By forming such a flow in the tank, the efficiency in the tank can be increased. In addition, while generating a crystallization reaction, particles having a desired particle size or more can be efficiently deposited and discharged at the bottom of the tank.

It is the figure which showed an example of the crystallization reaction tank which concerns on embodiment of this invention, and the crystallization classification apparatus containing this. It is the enlarged view which extracted and showed the principal part of the crystallization reaction tank which concerns on embodiment of this invention. It is the figure which showed the parameter setting and simulation result of the crystallization reaction tank which concerns on embodiment of this invention. FIG. 3A is a diagram showing an example of parameter setting of the crystallization reaction tank according to the embodiment of the present invention. FIG. 3B is a diagram showing a simulation result of the flow of the crystallization raw material in the crystallization reaction tank according to the present embodiment. It is the figure which showed the parameter setting and simulation result of the crystallization reaction tank which concerns on the comparative example 1. FIG. FIG. 4A is a diagram showing an example of parameter settings for the crystallization reaction tank according to Comparative Example 1. FIG. FIG. 4B is a diagram showing a simulation result of the flow of the crystallization raw material in the crystallization reaction tank according to Comparative Example 1. It is the figure which showed the parameter setting and simulation result of the crystallization reaction tank which concerns on the comparative example 2. FIG. FIG. 5A is a diagram showing an example of parameter setting of the crystallization reaction tank according to Comparative Example 2. FIG. 5B is a diagram showing a simulation result of the flow of the crystallization raw material in the crystallization reaction tank according to Comparative Example 2. It is the figure which showed concentration distribution of the solid particle | grains of the crystallization reaction tank concerning the comparative examples 3 and 4. FIG. FIG. 6A is a view showing the concentration distribution of solid particles in the entire crystallization reaction tank according to Comparative Example 3. FIG. 6B is an enlarged view of the bottom of FIG. FIG. 6C is a diagram showing the concentration distribution of solid particles in the entire crystallization reaction tank according to Comparative Example 4. FIG.6 (d) is the figure which expanded the bottom part of FIG.6 (c).

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a view showing an example of a crystallization reaction tank and a crystallization classification apparatus including the same according to an embodiment of the present invention. The crystallization reaction tank 50 according to the embodiment of the present invention includes a stirring tank 10, a stirrer 20, a draft tube 30, a draft tube fixing jig 35, and a baffle plate 40. In addition to the crystallization reaction tank 50, the crystallization classification apparatus 100 further includes a crystallization raw material supply device 60 and a classification outlet 70.

  The stirring tank 10 is a means for holding the crystallization raw material 110 in the tank, and is a means for stirring the crystallization raw material 110 held in the tank to generate and accelerate the crystallization reaction. The crystallization raw material 110 is in a liquid state or a slurry state composed of liquid and fine particles when the raw material is charged, but as the crystallization reaction proceeds, solid particles 111 are generated and the particle size of the solid particles 111 increases. Go. Therefore, the stirring tank 10 normally holds the crystallization raw material 110 in which the liquid and the solid particles 111 are mixed in the tank.

  The stirring tank 10 is preferably configured in a cylindrical shape having a mirror bottom. By having the said shape, it becomes easy to form the circulation flow which circulates up and down. A specific description of the circulation flow will be described later.

  As the crystallization raw material 110, various raw materials may be selected according to the crystallization target and application, but for example, the crystallization raw material 110 for crystallizing the Ni solid particles 111 may be used.

  The stirrer 20 is a stirring means for stirring the crystallization raw material 110 in the stirring tank 10. The stirrer 20 includes a rotating shaft 21, a main stirring blade support part 22, a main stirring blade 23, an auxiliary stirring blade support part 24, an auxiliary stirring blade 25, and a motor 26. The rotary shaft 21 may be provided at an arbitrary position in the stirring tank 10, but is generally provided near the center of the stirring tank 10, and by rotating the main stirring blade 23 and the auxiliary stirring blade 25, It is installed so that a symmetrical flow can be generated in the stirring tank 10 around the rotation shaft 21. The rotating shaft 21 extends in the vertical direction and rotates the main stirring blade 23 and the auxiliary stirring blade 25 horizontally.

  The main stirring blade support portion 22 is a support means for supporting the main stirring blade 23. The main stirring blade support 22 is fixed to the rotating shaft 21 and plays a role of transmitting the rotation of the rotating shaft 21 to the main stirring blade 23.

  The main stirring blade 23 may be configured to have various shapes depending on the application. For example, in order to form a vertical flow of the crystallization raw material 110 in the draft tube 30, the main stirring blade 23 may be arranged horizontally or vertically. It may be provided with an inclination. By being provided with an inclination, it is possible to form a vertical flow that extrudes the crystallization raw material 110 up and down. Details of the configuration of the stirring blade 23 will be described later.

  The main stirring blade 23 preferably has a shape extending in the horizontal direction (left-right direction) around the rotation shaft 21. Thereby, the rotation of the rotating shaft 21 can be efficiently transmitted to the crystallization raw material 110 without loss, and a flow symmetrical to the rotating shaft 21 can be formed.

  One or more main stirring blades 23 are provided around the main stirring blade support portion 22. When each of the main stirring blades 23 extending left and right around the rotating shaft 21 is counted as one, at least one main stirring blade 23 is provided, and a plurality of main stirring blades 23 may be further provided depending on the application. In the present embodiment, an example in which two main stirring blades 23 are provided in each of the upper stage and the lower stage will be described.

  The main stirring blade support portion 22 and the main stirring blade 23 may be provided in a plurality of stages in the vertical direction. In FIG. 1, the stirring blade support portion 22 and the stirring blade 23 are provided one unit at each of the upper stage and the lower stage. When the length of the stirring tank 10 is increased, it becomes difficult to produce a sufficient flow of the crystallization raw material 110 with only one stage. Therefore, when the stirring tank 10 is vertically long, the main stirring blade support 22 and In many cases, the main stirring blades 23 are provided one unit at each of the upper stage and the lower stage. Also in this embodiment, an example in which the main stirring blade support portion 22 and the main stirring blade 23 are provided in the upper stage and the lower stage will be described.

  The main stirring blade 23 is configured to form an upward flow in the vertical flow. In this embodiment, in addition to the main stirring blade 23 being provided inside the draft tube 30, the auxiliary stirring blade 25 is provided above the draft tube 30, and the auxiliary stirring blade 25 is crystallized in the downward direction. It plays the role of forming a flow of raw material 110. Therefore, the main stirring blade 23 functions to form an upward flow of the crystallization raw material 110 in the draft tube 30 so as to form a vertical circulation flow between the inside and outside of the draft tube 30.

  The auxiliary stirring blade 25 is a stirring blade provided to form a downward flow and rectify the outside of the draft tube 30, that is, between the outer peripheral surface of the draft tube 30 and the inner peripheral surface of the stirring tank 10. Since the main agitating blade 23 can independently form a circulating flow in the vertical direction between the inside and outside of the draft tube 30, the circulating flow itself can be formed even if the auxiliary agitating blade 25 is not provided. it can. However, since the main stirring blade 23 is provided inside the draft tube 30, the influence on the downward flow of the draft tube 30 is naturally weakened. Therefore, in the crystal precipitation reaction tank 50 according to the present embodiment, the auxiliary stirring blade 25 is installed on the upper outer side of the draft tube 30 and stirred to strengthen the downward flow from the upper part to the lower part of the stirring tank 10. In addition, the circulation flow formed in the entire stirring tank 10 is strengthened to increase the rectifying effect. Thereby, a favorable circulation flow can be formed in the whole inside of the stirring tank 10, and a crystallization reaction can be promoted.

  From this point of view, the auxiliary stirring blade 25 is provided outside the draft tube 30 both in the height direction and in the radial direction, and acts only on the downward flow of the crystallization raw material 110 outside the draft tube 30. 30 is arranged so as not to affect the upward flow inside.

  The auxiliary stirring blade support part 24 is a member for supporting the auxiliary stirring blade 25, is fixed to the rotary shaft 21, extends radially from the rotary shaft 21 along the radial direction, and extends the outer auxiliary stirring blade 25 to the inner side. Support from. The auxiliary agitating blade support portion 24 is composed of a rod-like member such as a cylinder or a prism that does not have a paddle-like shape, and is configured so as not to affect the upward flow in the draft tube 30.

  As described above, the crystallization reaction tank 50 and the crystallization classification apparatus 100 according to the present embodiment are provided by providing the main stirring blade 23 in the draft tube 30 and the auxiliary stirring blade 25 outside the draft tube 30. A good circulating flow in the vertical direction of the crystallization raw material 110 can be formed.

  The motor 26 is a driving means for rotating the main stirring blade 23 and the auxiliary stirring blade 25 via the main stirring blade support portion 22 and the auxiliary stirring blade support portion 24, and the main stirring blade 23 and the auxiliary stirring blade 25 are rotated. Various motors 26 may be used as long as they can be rotated at an appropriate speed and torque.

  The draft tube 30 is provided to adjust the flow in the stirring tank 10 and functions as a rectifying member. The draft tube 30 has a cylindrical shape and is provided so as to surround a predetermined depth region around the rotary shaft 21 and the main stirring blade 23. The draft tube 30 follows the flow of the crystallization raw material 110 formed by the main stirring blade 23 in the vertical direction along the inner peripheral surface thereof, and forms a unidirectional flow, that is, an upward flow in the draft tube 30. Play a role.

  In order to appropriately form such an upward flow of the crystallization raw material 110, it is preferable to appropriately set the diameter (inner diameter) of the draft tube 30 serving as the rectifying member with respect to the horizontal diameter of the stirring blade 23. . That is, even in the cooperation of the main stirring blade 23 and the auxiliary stirring blade 25, a circulation flow inside and outside the draft tube 30 can be formed, but by setting the draft tube 30 appropriately, a better circulation flow can be achieved. Can be formed. In the present embodiment, an appropriate setting method for such a draft tube 30 will also be described, and the detailed contents thereof will be described later.

  In addition, the draft tube 30 can be comprised with various materials, for example, may be comprised from stainless steel.

  The draft tube fixing jig 35 is a jig for fixing the draft tube 30. FIG. 1 shows a configuration in which the draft tube fixing jig 35 is fixed to the baffle plate 40 and the draft tube fixing jig 35 fixes the inner draft tube 30. 35 may have various configurations as long as the draft tube 30 can be fixed at an appropriate position.

  The baffle plate 40 is a baffle plate for converting the flow of the crystallization raw material 110 in the horizontal direction and the oblique direction into the vertical direction or the axial flow direction, and extends in the vertical direction along the inner peripheral side surface of the stirring tank 1. At the same time, it is provided so as to protrude toward the center of the stirring tank 10, that is, toward the rotating shaft 21. Specifically, the baffle plate 40 plays a role of forming a vertical flow of the crystallization raw material 110 between the outer peripheral side surface of the draft tube 30 and the inner peripheral side surface of the stirring tank 10. As described above, when a one-way flow in the vertical direction is formed inside the draft tube 30, a one-way flow in the vertical direction inside the draft tube 30 between the draft tube 30 and the stirring vessel 10. And a vertical flow in the opposite direction. Thereby, the crystallization raw material 110 can form a circulating flow that circulates up and down inside and outside the draft tube 30, promotes the crystallization reaction, and efficiently increases the crystallized solid particles 111 depending on the particle size. Can be divided up and down. That is, the solid particles 111 that have not reached the predetermined particle size can be raised by the upward flow, and the solid particles 111 that have reached the predetermined particle size are quickly deposited on the bottom of the agitation tank 10. Can do.

  The baffle plates 40 are provided so as to sandwich the draft tube 30 from both sides, that is, in pairs. For example, only one pair of baffle plates 40 may be provided so as to sandwich the draft tube 30 from the left and right, or two pairs may be provided so as to sandwich the draft tube 30 from four directions. Or more may be provided as needed. Thus, the number of baffle plates 40 may be appropriately determined according to the application. The baffle plate 40 may be referred to as a baffle 40.

  The above is the constituent elements of the crystallization reaction tank 50 according to the embodiment of the present invention. The crystallization classification apparatus 100 according to the embodiment of the present invention further includes a crystallization raw material input device 60 and a classification outlet 70. .

  The crystallization raw material charging device 70 is a means for charging the crystallization raw material 110 into the stirring tank 10, and includes a crystallization raw material tank 61 and a crystallization raw material charging port 62. The crystallization raw material tank 61 is a tank for accumulating the crystallization raw material 110, and stores, for example, a slurry-like crystallization raw material 110. The crystallization raw material charging port 62 is a raw material charging port or a raw material supply port for charging or supplying the crystallization raw material 110 accumulated in the crystallization raw material tank 61 into the stirring tank 10.

  The classification outlet 70 is a product outlet for discharging fixed particles having a predetermined particle diameter or more from the stirring tank 10, and is provided connected to the bottom of the stirring tank 10. Thereby, the classified solid particles 111 having a desired particle diameter can be obtained.

  FIG. 2 is an enlarged view showing an extracted main part of the crystallization reaction tank 50 according to the embodiment of the present invention. As shown in FIG. 2, a draft tube 30 is provided around the main stirring blade 23 of the stirrer 20, and an auxiliary stirring blade 25 is provided above the outside of the draft tube 30. Further, a baffle plate 40 is provided on the inner peripheral side surface of the stirring tank 10 outside the draft tube 30.

  Here, the stirrer 20 includes a main stirring blade 23 having a rotating shaft 21 provided at the shaft center of the stirring tank 10 and rotatable in the draft tube 30, and an auxiliary stirring blade 25 rotatable in the upper outside of the draft tube 30. Have The main stirring blade 23 and the auxiliary stirring blade 25 have a shape having a function of generating an axial flow, such as an inclined paddle and an inclined turbine. The shapes and dimensions of the main stirring blade 23 and the auxiliary stirring blade 25 can be determined by simulation by setting the flow velocity inside and outside the draft tube on the basis of the true specific gravity of the particles and the end speed of the particle diameter to be classified. The main stirring blade 23 is configured as an inclined stirring paddle in both the upper stage and the lower stage, and extends horizontally outward from the main stirring blade support member 22, intersects at right angles with each other, and forms a cross. Two are provided. Further, the auxiliary stirring blade 25 also extends above the draft tube 30 so that the auxiliary stirring blade support 24 extends radially and outward from the draft tube 30 so as to form a cross from the rotating shaft 21, and the auxiliary stirring blade 25 has an auxiliary stirring at its tip. Wings 25 are provided. In FIG. 2, two pairs of auxiliary stirring blades 25 are provided in a cross shape, but the number and shape of the auxiliary stirring blades 25 can be variously configured according to the application.

  Further, the draft tube 30 is provided so as to be supported upright on the axial center portion in the stirring tank 10. The draft tube 30 has a cylindrical shape and is provided so as to cover the stirring blade 23 at a predetermined interval from the tip of the stirring blade 23. By installing the draft tube 30, a rectifying effect in the stirring tank 10, a stirrer power reduction by the rectification, and a slurry separation effect are expected.

  One or more baffle plates 40 are installed radially so as to protrude toward the axis of the agitation tank 10. FIG. 2 shows an example in which two pairs of baffle plates 40 are installed so as to form a cross from four directions.

  As described above, the crystallization reaction tank 50 according to the embodiment of the present invention has a configuration in which the draft tube 30 is provided around the stirring blade 23.

  Next, the result of obtaining the ratio of the diameter of the draft tube to the total length of the stirring blade 23 such that the crystallization raw material 110 forms a vertical flow in the draft tube 30 will be described by a simulation experiment. The simulation experiment is performed for the stirrer 20 in the case where only the main stirring blade 23 is provided without providing the auxiliary stirring blade 25, but the correlation with the draft tube 30 is overwhelmed by the main stirring blade 23. Since the auxiliary stirring blade 25 is configured to affect only the downward flow outside the draft tube 30, the simulation experiment is almost as it is, and the crystallization reaction tank 50 and the crystallization classification according to the present embodiment. Applicable to the apparatus 100.

  In the simulation experiment, the stirring tank 10 has a diameter of 430 mm, the main stirring blade 23 has a diameter of 170 mm, a paddle width of 25 mm, a four-pitch paddle, a draft tube length of 330 mm, and a lower end position of 75 mm from the bottom of the stirring tank 10 Liquid specific gravity: solid specific gravity = 1: With the liquid phase height from the bottom surface of the tank 10 set to 445 mm and the rotation speed of the main stirring blade 23 set to 600 rpm, the continuous phase is liquid and the dispersed phase is 50 μm solid particles. 43.

  FIG. 3 is a diagram showing parameter settings and simulation results of the crystallization reaction tank 50 according to the embodiment of the present invention. FIG. 3A is a diagram showing an example of parameter setting of the crystallization reaction tank 50 according to the embodiment of the present invention. As shown in FIG. 3A, in an example of the crystallization reaction tank 50 according to the present embodiment, when the total length of the main stirring blade 23 is d and the diameter of the draft tube 30 is D, D / d = 1.4.

  FIG. 3B shows the crystallization raw material 110 in the crystallization reaction tank 50 according to the embodiment when the ratio D / d of the diameter D of the draft tube 30 to the total length d of the main stirring blade 23 is 1.4. It is the figure which showed the simulation result of the flow.

  As shown in FIG. 3B, almost all of the flow of the crystallization raw material 110 in the draft tube 30 is an upward flow, and an upward axial flow is formed. Further, between the draft tube 30 outside the draft tube 30 and the inner peripheral side surface of the agitation tank 10, almost everything is a downward flow, and a circulating flow is formed that circulates inside and outside the side surface of the draft tube 30. Has been. Thus, by appropriately setting the ratio between the diameter D of the draft tube 30 and the total length d of the main stirring blade 23, the inside of the draft tube 30 flows in one direction in the vertical direction, and the outside of the draft tube 30. Thus, a circulation flow that flows in the other direction of the vertical direction opposite to the inside of the draft tube 30 can be formed, and the crystallization raw material 110 can be efficiently circulated in the axial flow direction.

  Note that D / d = 1.4 is an example, and the ratio D / d of the diameter D of the draft tube to the total length d of the main stirring blade 23 may be various as long as a circulating flow can be formed inside and outside the draft tube 30. Value can be set.

  Thus, in the crystallization reaction tank 50 and the crystallization classification apparatus 100 according to the present embodiment, the draft tube 30 is installed in the stirring tank 10 to form a stable circulation flow in the tank, and the center of the tank bottom. In addition, a stable rising flow at a low speed is formed, and a classification function for efficiently depositing particles having a desired particle size or more in that region is provided.

  Next, the parameter setting of the crystallization reaction tank according to the comparative example will be described.

  FIG. 4 is a diagram showing parameter settings and simulation results of the crystallization reaction tank according to Comparative Example 1. FIG. 4A is a diagram showing an example of parameter settings for the crystallization reaction tank according to Comparative Example 1. FIG. As shown in FIG. 4 (a), in the crystallization reaction tank according to Comparative Example 1, when the total length of the main stirring blade 123 is d and the diameter of the draft tube 130 is D, D / d = 1. Set to 1. In this case, the distance between the tip of the main stirring blade 123 and the inner peripheral surface of the draft tube 130 is such that the tip of the stirring tank 23 and the draft of the crystallization reaction tank 50 according to the embodiment shown in FIG. The distance from the tube 30 is narrower.

  FIG. 4B shows the crystallization raw material 110 in the crystallization reaction tank according to Comparative Example 1 when the ratio D / d of the diameter D of the draft tube 130 to the total length d of the main stirring blade 123 is 1.1. It is the figure which showed the simulation result of the flow.

  As shown in FIG. 4 (b), the left upward flow formed by the main stirring blade 123 collides with the inner peripheral surface of the draft tube 130 in the middle, forming a flow that rises meanderingly. Has been. Further, on the outside of the draft tube 130, an oblique downward flow toward the draft tube 130 is formed on the left side, and an upward flow is formed on the upper side on the right side, so that no circulation flow is formed as a whole.

  Thus, if the distance between the main stirring blade 123 and the draft tube 130 is short and they are too close to each other, the main stirring blade 123 and the draft tube 130 interfere with each other, and a circulation flow is not formed.

  Therefore, the crystallization reaction tank 50 according to the present embodiment needs to satisfy 1.1 <D / d with respect to the ratio D / d of the diameter D of the draft tube to the total length d of the main stirring blade 23.

  FIG. 5 is a diagram showing parameter settings and simulation results of the crystallization reaction tank according to Comparative Example 2. FIG. 5A is a diagram showing an example of parameter setting of the crystallization reaction tank according to Comparative Example 2. As shown in FIG. 5A, in the crystallization reaction tank according to Comparative Example 2, when the total length of the main stirring blade 223 is d and the diameter of the draft tube 230 is D, D / d = 1. Set to 6. In this case, the distance between the tip of the main stirring blade 223 and the inner peripheral surface of the draft tube 230 is such that the tip of the stirring tank 23 and the draft of the crystallization reaction tank 50 according to the embodiment shown in FIG. It becomes wider than the interval between the tubes 30.

  FIG. 5B shows the crystallization raw material 110 in the crystallization reaction tank according to Comparative Example 2 when the ratio D / d of the diameter D of the draft tube 230 to the total length d of the main stirring blade 223 is 1.6. It is the figure which showed the simulation result of the flow.

  As shown in FIG. 5 (b), the upward flow formed by the main stirring blade 223 changes its direction before reaching the upper end of the draft tube 30 and becomes a downward flow, and a circulating flow is generated in the draft tube 230. It has been done. As a result, the upward and downward flows are mixed in the draft tube 230. When such a flow occurs, a circulating flow does not occur in the entire crystallization reaction tank.

  Thus, if the distance between the main stirring blade 223 and the draft tube 230 is too far, a circulation flow is generated inside the draft tube 230, and no circulation flow is formed in the entire crystallization reaction tank.

  Therefore, the crystallization reaction tank 50 according to the present embodiment needs to satisfy D / d <1.6 with respect to the ratio D / d of the diameter D of the draft tube to the total length d of the main stirring blade 23.

  Considering both Comparative Examples 1 and 2, the crystallization reaction tank 50 according to the embodiment of the present invention has a ratio D / d of the diameter D of the draft tube to the total length d of the main stirring blade 23, 1.1 <D It is necessary to satisfy /d<1.6.

  In order to form a stable circulating flow in the tank, the ratio D / d between the diameter D of the draft tube 30 and the total length d of the main stirring blade 23 is desirably 1.2 or more and 1.5 or less. . When D / d is less than 1.2, there is a risk that the main stirring blade 123 and the draft tube 130 interfere with each other due to eccentricity of the stirring shaft, as described with reference to FIG. On the other hand, when D / d = 1.5 or more, as described with reference to FIG. 5, a circulation flow may be formed inside the draft tube 230.

  FIG. 6 is a diagram showing the concentration distribution of solid particles in the crystallization reaction tank according to Comparative Examples 3 and 4 in which no draft tube is provided. FIG. 6A is a diagram showing the concentration distribution of solid particles in the entire crystallization reaction tank according to Comparative Example 3 in which no draft tube is provided, and FIG. 6B shows the bottom of FIG. FIG. FIG. 6 (c) is a diagram showing the concentration distribution of solid particles in the entire crystallization reaction tank according to Comparative Example 4 in which no draft tube is provided, and FIG. 6 (d) shows the bottom of FIG. 6 (c). FIG.

  6A to 6D, regions A, B, C, and D are shown in descending order of density. As shown in FIGS. 6A to 6D, when the draft tube 30 is not provided, the regions A to D are mixed in each part in the crystallization reaction tank. That is, it can be seen that there is a variation in the concentration inside and at the bottom of the crystallization reaction tank, and there is a variation in the particle size of the solid particles.

  On the other hand, as described with reference to FIGS. 1 to 5, according to the crystallization reaction tank 50 and the crystallization classification apparatus 100 according to the present embodiment, the draft tube 30 is provided around the main stirring blade 23, and the draft tube 30 is provided. A circulating flow that circulates inside and outside the draft tube 30 by providing an auxiliary stirring blade 25 on the upper side and further appropriately setting the ratio D / d between the diameter D of the draft tube 30 and the total length d of the main stirring blade 23. , And the circulation rate can be increased, and solid particles 111 having a desired particle size or more can be efficiently deposited and discharged at the bottom of the tank while efficiently allowing a crystallization reaction in the tank.

  The preferred embodiments and examples of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments and examples, and the above-described embodiments and examples can be performed without departing from the scope of the present invention. Various modifications and substitutions can be made to the embodiments.

DESCRIPTION OF SYMBOLS 10 Stirring tank 20 Stirrer 21 Rotating shaft 22 Main stirring blade support part 23 Main stirring blade 24 Auxiliary stirring blade support part 25 Auxiliary stirring blade 26 Motor 30 Draft tube 35 Draft tube fixing jig 40 Baffle plate 50 Crystallization reaction tank 60 Crystallization Raw material feeder 61 Crystallization raw material tank 62 Crystallization raw material input port 70 Classification outlet 100 Crystallization classification device 110 Crystallization raw material 111 Solid particles

Claims (8)

A stirring tank for holding the crystallization raw material;
A rotating shaft extending vertically in the stirring tank;
A draft tube provided to surround a predetermined depth region around the rotation axis;
A first stirring blade fixed to the rotating shaft and provided in the draft tube;
A crystallization reaction tank having a second stirring blade fixed to the rotating shaft and provided outside the draft tube.   The crystallization reaction tank according to claim 1, wherein the second stirring blade is provided above the draft tube. The first stirring blade is provided in the draft tube so as to form a flow upward in the crystallization raw material,
The crystallization reaction tank according to claim 2, wherein the second stirring blade is provided so as to form a downward flow of the crystallization raw material outside the draft tube.   4. The crystallization reaction tank according to claim 3, wherein the second stirring blade is supported by a support portion extending radially from the rotation shaft, and is provided only on the outer side of the draft tube in the radial direction.   The ratio of the diameter of the draft tube to the total length of the first stirring blade is such that the flow direction of the crystallization raw material in the draft tube is one direction in the upward direction, and the inner circumference of the draft tube and the stirring tank The crystallization reaction tank according to claim 3 or 4, wherein the flow direction of the crystallization raw material with respect to the surface is set so as to be one direction of the lower direction.   6. The crystallization reaction tank according to claim 5, wherein a ratio of a diameter of the draft tube to a total length of the first stirring blade is in a range larger than 1.1 and smaller than 1.6.   The crystallization reaction tank according to any one of claims 1 to 6, wherein the first and second stirring blades are configured as inclined paddles. A crystallization reaction tank according to any one of claims 1 to 7,
A crystallization raw material inlet for supplying the crystallization raw material to the crystallization reaction tank;
A crystallization classifier having a classification outlet provided at the bottom of the crystallization reaction tank for discharging solid particles having a predetermined particle diameter or more.