Patent Publication Number: US-2023133177-A1

Title: Dispersing and grinding device

Description:
TECHNICAL FIELD 
     The present invention relates to a device (hereinafter referred to as “dispersing and grinding device”) for dispersing or grinding particles contained in a liquid (hereinafter referred to as “particle-containing liquid”), and more particularly, to a medialess dispersing and grinding device which does not involve use of media such as beads. 
     BACKGROUND ART 
     Hitherto, as a medialess dispersing and grinding device that disperses or grinds particles contained in a particle-containing liquid, there has been known a dispersing and grinding device (Patent Literature 1) which has been filed by the applicant of the subject application prior to filing of the subject application. This dispersing and grinding device is configured to disperse or grind particles contained in a particle-containing liquid with a shear force generated when the particle-containing liquid passes through a gap defined between a casing and a rotor. 
     The above-mentioned dispersing and grinding device can disperse or grind particles on a micro scale without causing contamination, which may occur when use of media is involved. 
     CITATION LIST 
     Patent Literature 
     
         
         [PTL 1] JP 6799865 B2 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In order to disperse or grind the particles in the particle-containing liquid into finer particles, a shear rate (shear velocity) is required to be increased. The dispersing and grinding device described in Patent Literature 1 achieves an increase in shear rate through high-speed rotation of a rotor (rotating body). When the rotor is rotated at high speed, however, the particle-containing liquid may generate heat, leading to material degradation due to the heat. Further, large energy is required to rotate the rotor at high speed. There is a limit even when the rotor is rotated at high speed, and thus it is difficult to obtain fine particles of a size that is only achievable with use of a dispersing and grinding device that involves use of media. 
     The present invention has been made in view of the circumstances described above, and has an object to provide a dispersing and grinding device that is capable of increasing a shear rate with energy smaller than energy required by a related-art medialess dispersing and grinding device, and thus dispersing or grinding particles into particles finer than particles obtained by the related-art medialess dispersing and grinding device. 
     Solution to Problem 
     According to the present invention, there is provided a dispersing and grinding device for dispersing or grinding particles in a particle-containing liquid with a shear force generated when the particle-containing liquid passes through a gap, the dispersing and grinding device including: a casing having an inflow portion configured to allow the particle-containing liquid to flow into the casing and an outflow portion configured to allow the particle-containing liquid to flow out of the casing; a rotor, a stator, and an impeller (rotating body with vanes) that are arranged inside the casing; and drive means for rotating the rotor and the impeller. The gap is defined between the stator and the rotor. When the rotor and the impeller are rotated by the drive means, the particle-containing liquid is allowed to flow into the casing through the inflow portion by a rotating force of the impeller, and passes through the gap to cause the particles in the particle-containing liquid to be dispersed or ground with a shear force generated when the particle-containing liquid passes through the gap. 
     Advantageous Effects of Invention 
     The dispersing and grinding device according to the present invention can increase the shear rate with energy smaller than that required by a related-art medialess dispersing and grinding device owing to an action of the impeller provided in the casing, and thus can disperse or grind the particles contained in the particle-containing liquid into particles finer than those obtained by the related-art medialess dispersing and grinding device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic explanatory view of a circulation treatment system in which a dispersing and grinding device according to the present invention is installed. 
         FIG.  2    is a sectional view for illustrating an internal structure of the dispersing and grinding device according to the present invention. 
         FIG.  3    is a sectional view for illustrating the internal structure of the dispersing and grinding device according to the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 
     An example of a dispersing and grinding device  10  according to an embodiment of the present invention is described with reference to the drawings. The dispersing and grinding device  10  of this embodiment is installed and used in a treatment system as illustrated in  FIG.  1   . Examples of the treatment system include a circulation treatment system and a pass treatment system. In this embodiment, there is described as an example a case in which the dispersing and grinding device  10  is installed in a circulation treatment system. 
     As an example, the treatment system illustrated in  FIG.  1    includes a particle-containing liquid tank  20 , the dispersing and grinding device  10 , and a three-way valve  30 . The particle-containing liquid tank  20  is configured to store a particle-containing liquid (slurry) being a target to be treated. The dispersing and grinding device  10  is configured to disperse or grind particles contained in the particle-containing liquid supplied from the particle-containing liquid tank  20 . The three-way valve  30  is configured to change a flow passage for the particle-containing liquid which has passed through the dispersing and grinding device  10 . 
     The particle-containing liquid tank  20  and the dispersing and grinding device  10  are connected to each other through a first flow passage  31 . The dispersing and grinding device  10  and the three-way valve  30  are connected to each other through a second flow passage  32 . The three-way valve  30  and the particle-containing liquid tank  20  are connected to each other through a third flow passage  33 . A valve  35  configured to open and close the first flow passage  31  is provided in the first flow passage  31 . For example, an existing automatic valve may be used as the valve  35 . 
     The particle-containing liquid tank  20  is a container configured to store the particle-containing liquid being the target to be treated. In this embodiment, a jacket tank is used as the particle-containing liquid tank  20 . The jacket tank includes a stirring vessel  21  and a jacket  22  mounted onto an outer periphery of the stirring vessel  21 . Other containers may be used as the particle-containing liquid tank  20 . 
     The stirring vessel  21  is a container configured to store the particle-containing liquid and allow the particle-containing liquid to be stirred therein. The stirring vessel  21  of this embodiment has a bottomed cylindrical shape with an upper opening. A stirring-vessel discharge port  21   a  that allows the particle-containing liquid in the stirring vessel  21  to be discharged to an outside is formed in a bottom surface of the stirring vessel  21 . The upper opening of the stirring vessel  21  can be opened and closed by a lid  24 . 
     A stirring rod  23  with vanes that is configured to stir the particle-containing liquid in the stirring vessel  21  is provided inside the stirring vessel  21 . The stirring rod  23  is rotated by a stirring motor M that is placed on the lid  24  configured to open and close the upper opening of the stirring vessel  21 . The lid  24  has a feedback port  24   a  to which an outlet side of the third flow passage  33  is connected. The particle-containing liquid which has passed through the third flow passage  33  is fed back into the stirring vessel  21  through the feedback port  24   a.    
     The jacket  22  is configured to allow circulation of cooling water for cooling the particle-containing liquid stored in the stirring vessel  21 . A cooling-water introduction port  22   a  that allows the cooling water to be introduced into the jacket  22  is formed in a bottom surface of the jacket  22 . A cooling-water discharge port  22   b  that allows the cooling water to be discharged to an outside of the jacket  22  is formed in a side surface of the jacket  22 . Although not shown, a chiller (cooling-water circulating device) including a cooling-water introduction passage and a cooling-water discharge passage is connected to the cooling-water introduction port  22   a  and the cooling-water discharge port  22   b . This structure allows the cooling water supplied from the chiller to circulate inside the jacket  22 . 
     The dispersing and grinding device  10  is configured to disperse or grind particles contained in the particle-containing liquid with a shear force generated when the particle-containing liquid passes through a gap S ( FIG.  2   ). The term “disperse” means that powder is separated as fine as possible into single particles and the particles are distributed into a fluid or other components in a uniform manner or while forming a structure. The term “grind” means an operation of pulverizing a material into powder. 
     As illustrated in  FIG.  2   , the dispersing and grinding device  10  according to this embodiment includes a casing  11 , a housing  12 , a rotor  13 , an impeller  14 , drive means  15 , a stator  16 , and an intermediate member  17 . 
     The casing  11  is a case configured to receive the particle-containing liquid stored in the particle-containing liquid tank  20  inside. The particles contained in the particle-containing liquid, which has been introduced into the casing  11 , are dispersed or ground inside the casing  11 . The casing  11  of this embodiment has an inflow portion  11   a  having a tubular shape, an accommodating portion  11   b  having a hollow conical shape (trumpet-like shape), and an outflow portion  11   c  having a tubular shape. The particle-containing liquid flows into the casing  11  through the inflow portion  11   a . Components such as the rotor  13  and the impeller  14  are accommodated in the accommodating portion  11   b . The particle-containing liquid flows out of the casing  11  through the outflow portion  11   c . As illustrated in  FIG.  3   , the outflow portion  11   c  is formed to extend in a tangential direction to the casing  11 . 
     The inflow portion  11   a , the accommodating portion  11   b , and the outflow portion  11   c  of the casing  11  communicate with each other inside the casing  11 . This structure allows the particle-containing liquid, which has flowed into the casing  11  through the inflow portion  11   a , to pass through the accommodating portion  11   b  and flow to an outside of the casing  11  through the outflow portion  11   c . The casing  11  includes a larger-end side flange  11   d  projecting outward that is formed at a larger end of the casing  11  (end of the casing  11  on a side opposite to the inflow portion  11   a ). 
     The housing  12  is a case in which the drive means  15  is accommodated. The housing  12  of this embodiment includes a body portion  12   a  and a brim-shaped portion  12   b  having a disc-like shape. The drive means  15  is accommodated in the body portion  12   a . The brim-shaped portion  12   b  projects outward from an end of the body portion  12   a . An outwardly projecting portion  17   c  of the intermediate member  17  described later is brought into contact with the brim-shaped portion  12   b , and the outwardly projecting portion  17   c  and the brim-shaped portion  12   b  are fixed together with use of a first fixture B 1 . 
     The rotor  13  is a disc-shaped member having a diameter smaller than a diameter of the brim-shaped portion  12   b  of the housing  12 . The rotor  13  is provided on a distal end side of a rotary shaft  15   a  of the drive means  15 . A mixed flow impeller (mixed flow pump) is provided as the impeller  14  on a front surface (on the inflow portion  11   a  side) of the rotor  13 . The mixed flow impeller allows a generated flow to move within a conical surface having a center line of its main shaft as an axis. 
     The mixed flow impeller has a large flow rate, and thus can increase pressure. Thus, the particle-containing liquid is forced to pass through the gap S at high speed and high pressure. When the flow rate is increased with use of the mixed flow impeller, the particle-containing liquid passes faster to enable suppression of heat generation. Further, when the flow rate is increased with use of the mixed flow impeller, the effects of increasing the number of passages of the circulating particle-containing liquid are achieved to thereby more easily provide homogenous products. 
     A retainer  18  configured to retain the rotor  13  and the impeller  14  is arranged on a distal end side of the impeller  14 . The retainer  18  is fixed to a distal end of the rotary shaft  15   a  together with the rotor  13  and the impeller  14  with use of a second fixture B 2 . The impeller  14  is rotated together with the rotor  13  and the retainer  18  in the same direction as a rotating direction of the rotary shaft  15   a  through rotation of the rotary shaft  15   a  of the drive means  15  described later. 
     The drive means  15  is means for rotating the rotor  13  and the impeller  14 . The drive means  15  of this embodiment includes a motor (not shown) and the rotary shaft  15   a  coupled to the motor. A mechanical seal  19  configured to prevent outflow of the particle-containing liquid is provided at an outer periphery of the rotary shaft  15   a.    
     The stator  16  is a member configured to create a flow of the particle-containing liquid in cooperation with the rotor  13  and the impeller  14 . The stator  16  of this embodiment is a disc-shaped member having an opening formed in a center, which allows accommodation of the impeller  14 . The stator  16  includes a flange portion  16   a  projecting outward. The flange portion  16   a  is brought into contact with the intermediate member  17  described later, and the flange portion  16   a  and the intermediate member  17  are fixed together with use of a third fixture B 3 . 
     A protrusion  16   b  having an annular shape is formed on a surface of the stator  16 , which is on a side closer to the rotor  13 , so as to be opposed to the rotor  13 . The extremely small gap S through which the particle-containing liquid passes is defined between the protrusion  16   b  and the rotor  13 . A dimension of the gap S may be set to 100 μm or smaller, preferably, 70 μm or smaller, more preferably, 30 μm or smaller. 
     Although not shown, a groove including a protrusion and a recess may be formed on a surface (surface opposed to the rotor  13 ) of the stator  16 , which defines the gap S. The groove formed on the surface of the stator  16  enables dispersion or grinding of the particles contained in the particle-containing liquid to finer particles. The groove including a protrusion and a recess may be formed to extend in a direction parallel to a direction of passage of the particle-containing liquid or in a direction intersecting with the direction of passage of the particle-containing liquid. 
     The intermediate member  17  is a member arranged between the casing  11  and the stator  16 . The intermediate member  17  of this embodiment includes a cylindrical portion  17   a , an inwardly projecting portion  17   b , and the outwardly projecting portion  17   c . The cylindrical portion  17   a  is formed at such a position as to cover outsides of the stator  16 , the rotor  13  and the impeller  14 . The inwardly projecting portion  17   b  is formed on one end side of the cylindrical portion  17   a  so as to project inward therefrom. The outwardly projecting portion  17   c  is formed on another end side of the cylindrical portion  17   a  so as to project outward therefrom. 
     The flange portion  16   a  of the stator  16  is brought into contact with the inwardly projecting portion  17   b  of the intermediate member  17 , and the flange portion  16   a  and the inwardly projecting portion  17   b  are fixed together with use of the third fixture B 3 . The larger-end side flange  11   d  of the casing  11  is brought into contact with the outwardly projecting portion  17   c  of the intermediate member  17 , and the larger-end side flange  11   d  and the outwardly projecting portion  17   c  are fixed together with use of a fourth fixture B 4 . 
     In this embodiment, a shim (spacer), which is not shown, can be inserted into a space between the flange portion  16   a  of the stator  16  and the inwardly projecting portion  17   b  of the intermediate member  17 . The gap S between the rotor  13  and the protrusion  16   b  can be adjusted by inserting the shim into the space. 
     The cylindrical portion  17   a  of the intermediate member  17  has a plurality of openings  17   d  formed at intervals in a circumferential direction of the cylindrical portion  17   a . The openings  17   d  are formed at such positions as to enable the gap S between the rotor  13  and the stator  16  to be viewed from the outside. After the shim is inserted into the space between the flange portion  16   a  of the stator  16  and the inwardly projecting portion  17   b  of the intermediate member  17 , it can be checked through the openings  17   d  whether the gap S having a suitable width has been defined between the rotor  13  and the stator  16 . 
     The number and a size of the openings  17   d  may be suitably set. The opening  17   d  is required to have equal to or larger than a width (for example, a length of about 20 mm by a width of about 20 mm) checkable with use of a clearance gauge. The openings  17   d  also serve as passages for the particle-containing liquid. Thus, it is preferred that the openings  17   d  be as wide as possible. In any case, it is preferred that the openings  17   d  be formed at such positions as to enable the gap S between the rotor  13  and the stator  16  to be viewed. The openings  17   d  are only required to be formed as needed. 
     In the treatment system described in this embodiment, the particle-containing liquid stored in the particle-containing liquid tank  20  flows into the dispersing and grinding device  10  through the first flow passage  31 . When the treatment system performs a circulating operation, the particle-containing liquid which has passed through the dispersing and grinding device  10  passes through the second flow passage  32 , the three-way valve  30 , and the third flow passage  33  in the stated order, and then is fed back into the particle-containing liquid tank  20 . When the particle-containing liquid is discharged, the particle-containing liquid passes through the second flow passage  32  and the three-way valve  30  to be discharged into a fourth flow passage  34 . 
     Operation 
     Now, an operation of the dispersing and grinding device  10  of this embodiment in the treatment system is described. The rotary shaft  15   a  is rotated by the motor of the drive means  15 . Then, when the rotor  13  and the impeller  14 , which are coupled to the rotary shaft  15   a , are rotated, the particle-containing liquid flows into the casing  11  through the inflow portion  11   a . The particle-containing liquid which has flowed into the casing  11  moves into the accommodating portion  11   b , and then passes through the extremely small gap S along a flow passage defined by the impeller  14 . The particles in the particle-containing liquid are dispersed or ground with a shear force generated when the particle-containing liquid passes through the gap S. The particle-containing liquid which has passed through the gap S flows to the outside through the outflow portion  11   c.    
     The dispersing and grinding device  10  of this embodiment is installed in the circulation treatment system. Thus, the particle-containing liquid which has flowed out through the outflow portion  11   c  passes through the second flow passage  32  and the three-way valve  30 , and then is returned back to the particle-containing liquid tank  20  (stirring vessel  21 ) through the third flow passage  33 . After that, the treatment in the dispersing and grinding device  10  is repeated for a predetermined number of times to disperse or grind the particles into particles of a desired size. 
     The dispersing and grinding device  10  of this embodiment not only has the smaller gap S but also is configured to force the particle-containing liquid to pass through the gap S at high speed and high pressure owing to a pumping action of the mixed flow impeller. Thus, even though the dispersing and grinding device  10  is of a medialess type, the dispersing and grinding device  10  is expected to achieve a shear rate equal to or larger than a shear rate obtained by the dispersing and grinding device that involves use of media. Thus, the particles in the particle-containing liquid can be dispersed or ground into particles of a size (nano order) substantially equal to a size of particles obtained by the dispersing and grinding device that involves use of media. 
     For example, when the gap S is set to 30 μm, and a peripheral speed of the rotor  13  is set to 30 m/sec, the dispersing and grinding device  10  according to the present invention is expected to achieve a shear rate of about 1 million/sec, which corresponds to a shear rate of a high-pressure homogenizer. In addition, heat generation, which may be caused by high-speed rotation, is expected to be minimized. 
     Other Embodiments 
     The dispersing and grinding device according to the present invention is not limited to that described above in the embodiment. Changes such as addition or elimination of a configuration or interchange of configurations are possible without changing the gist of the invention. 
     The dispersing and grinding device  10  installed in the circulation treatment system has been described as an example in the embodiment. However, the dispersing and grinding device  10  according to the present invention may also be installed in a pass treatment system. 
     The use of the mixed flow impeller as the impeller  14  has been described as an example in the embodiment. However, an impeller other than the mixed flow impeller, for example, an axial flow impeller (axial flow pump) that feeds a particle-containing liquid in an axial direction may also be used as the impeller  14 . 
     The dispersing and grinding device  10  laid with its axial direction aligned with a horizontal direction when in use has been described as an example in the embodiment. However, the dispersing and grinding device  10  according to the present invention may be laid with its axial direction aligned with a vertical direction when in use. 
     INDUSTRIAL APPLICABILITY 
     The dispersing and grinding device  10  according to the present invention may be used for dispersion or grinding particles contained in various kinds of particle-containing liquids used for, for example, battery materials, cosmetic products, food, electronic components, and paint. 
     REFERENCE SIGNS LIST 
     
         
           10  dispersing and grinding device 
           11  casing 
           11   a  inflow portion 
           11   b  accommodating portion 
           11   c  outflow portion 
           11   d  larger-end side flange 
           12  housing 
           12   a  body portion 
           12   b  brim-shaped portion 
           13  rotor 
           14  impeller 
           15  drive means 
           15   a  rotary shaft 
           16  stator 
           16   a  flange portion 
           16   b  protrusion 
           17  intermediate member 
           17   a  cylindrical portion 
           17   b  inwardly projecting portion 
           17   c  outwardly projecting portion 
           17   d  opening 
           18  retainer 
           19  mechanical seal 
           20  particle-containing liquid tank 
           21  stirring vessel 
           21   a  stirring-vessel discharge port 
           22  jacket 
           22   a  cooling-water introduction port 
           22   b  cooling-water discharge port 
           23  stirring rod 
           24  lid 
           24   a  feedback port 
           30  three-way valve 
           31  first flow passage 
           32  second flow passage 
           33  third flow passage 
           34  fourth flow passage 
           35  valve 
         B 1  first fixture 
         B 2  second fixture 
         B 3  third fixture 
         B 4  fourth fixture 
         M stirring motor 
         S gap