JP7670955B2 - Powder Mixing and Dispersion System - Google Patents

Description

The present invention relates to a powder mixing and dispersion system, and more specifically, to a powder mixing and dispersion system equipped with a shear dispersion means for dispersing powder mixed in a liquid by shear.

Conventionally, there has been known a powder mixing and dispersion system that disperses powder mixed in a liquid, and one that includes a liquid storage tank that stores the liquid and a shear dispersion means that disperses the powder mixed in the liquid by shearing (Patent Document 1).
The system of Patent Document 1 is equipped with a circulation path for circulating a mixed fluid of liquid and powder between the liquid storage tank and the shear dispersion means, and the powder in the mixed fluid is dispersed while the mixed fluid is circulated between the liquid storage tank and the shear dispersion means via this circulation path.

Patent No. 6388501

However, in the system of Patent Document 1, the powder is directly added to the liquid in the storage tank and the powder is mixed into the liquid by rotating an agitator inside the storage tank. In this case, the powder floats on the surface of the liquid and is not sufficiently mixed even when stirred.
Furthermore, even if such a mixed fluid is circulated in a circulation path and dispersed by the above-mentioned shear dispersion means, the suspended powder cannot be sufficiently disintegrated because it is agglomerated, and so-called lumps form, resulting in particles remaining in the mixed fluid.
Completely breaking down and uniformly dispersing such lumps requires long periods of circulation, which takes time, so there is a demand for a powder mixing and dispersion system that can efficiently and uniformly disperse powder in a mixed fluid.
In view of these problems, the present invention provides a powder mixing and dispersion system that can thoroughly mix powder into liquid and efficiently disperse the powder uniformly in the mixed fluid.

That is , the present invention provides a powder mixing and dispersing system including a liquid storage tank for storing a liquid and a shear dispersing means for dispersing powder mixed in the liquid by shearing,
the liquid storage tank and the solid-liquid mixing means; a first circulation path for circulating the liquid between the liquid storage tank and the solid-liquid mixing means; a second circulation path for circulating a mixed fluid of liquid and powder between the liquid storage tank and the shear dispersion means; a third circulation path for circulating the mixed fluid from the liquid storage tank to the liquid storage tank without passing through either the solid-liquid mixing means or the shear dispersion means; a path switching means for switching between the first circulation path and the second circulation path ; and a bypass switching means for switching between the second circulation path and the third circulation path ,
The method is characterized in that the liquid is circulated between a liquid storage tank and a solid-liquid mixing means through the first circulation path while mixing powder into the liquid and storing the mixed fluid in the liquid storage tank, thereafter, the path switching means switches from the first circulation path to the second circulation path, and the mixed fluid stored in the liquid storage tank is circulated between the liquid storage tank and the shear dispersion means through the second circulation path while dispersing the powder in the mixed fluid, and thereafter, the bypass switching means switches from the second circulation path to a third circulation path, and the mixed fluid in which the powder has been dispersed is circulated through the third circulation path .

According to this configuration, first, the liquid is circulated between the storage tank and the solid-liquid mixing means through the first circulation path while the powder is mixed into the liquid, thereby obtaining a mixed fluid in which the liquid and powder are thoroughly mixed.
Thereafter, the path switching means switches from the first circulation path to the second circulation path, and the mixed fluid is circulated between the storage tank and the shear dispersion means via the second circulation path to disperse the powder in the mixed fluid. Since the powder in the circulated mixed fluid has been sufficiently mixed in advance, the powder in the mixed fluid can be efficiently and uniformly dispersed.

FIG. 1 is a configuration diagram of a powder dispersion system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 11 is a diagram for explaining the operation of the powder dispersion system according to the second embodiment. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system. FIG. 2 is a diagram illustrating the operation of the powder dispersion system.

The present invention will now be described with reference to the illustrated embodiments. FIG. 1 shows a schematic diagram of a powder mixing and dispersion system 1 that thoroughly mixes powder with a liquid to produce a mixed fluid, thereby efficiently dispersing the powder in the mixed fluid uniformly.
The powder may be, for example, food such as wheat flour, or inorganic materials such as carbon nanotubes or aluminum oxide, and it is also possible to mix a plurality of types of powder.
On the other hand, water is used as the liquid for dispersing food such as wheat flour, and a solvent made of an organic solvent (NMP: N-methylpyrrolidone, etc.) is used as the liquid for dispersing inorganic materials such as carbon nanotubes and aluminum oxide. Note that this embodiment is a system that creates a slurry in which solid particles are suspended in a liquid by mixing and dispersing carbon nanotubes in MNP.

The powder mixing and dispersion system 1 includes a liquid storage tank 2 for storing liquid L, a solid-liquid mixing means 3 for mixing powder P into the liquid L, and a shear dispersion means 4 for shearing and dispersing the powder P in a mixed fluid ML (see Figure 3) of the liquid L and the powder P, and the powder mixing and dispersion system 1 is controlled by a control means 5.
In the powder mixing and dispersion system 1 of this embodiment, a first circulation path C1 (see Figure 2) is formed between the liquid storage tank 2 and the solid-liquid mixing means 3, and a second circulation path C2 (see Figure 3) is formed between the liquid storage tank 2 and the shear dispersion means 4, and these first circulation path C1 and second circulation path C2 are switched by a path switching means described later.
With this configuration, first, the liquid L is circulated between the liquid storage tank 2 and the solid-liquid mixing means 3 via the first circulation path C1 while mixing the liquid L with the powder P to form a mixed fluid ML, and then, by switching from the first circulation path C1 to the second circulation path C2 by the path switching means, the powder in the mixed fluid ML is uniformly dispersed while circulating the mixed fluid ML between the liquid storage tank 2 and the shear dispersion means 4 via the second circulation path C2.

An agitating blade 2a is provided inside the liquid storage tank 2, and a sealing lid 2b is attached to the top to seal the liquid storage tank 2.
An outward pipe 6 for sending out the liquid L or the mixed fluid ML is connected to the bottom of the storage tank 2, and a return pipe 7 for returning the liquid L or the mixed fluid ML to the storage tank 2 is connected to the top. The outward pipe 6 is provided with a liquid delivery pump 8 consisting of a rotary pump for delivering the liquid L and the mixed fluid ML.
In addition, the outflow pipe 6 is provided with a cooling means 9 for cooling the mixed fluid ML flowing downstream of the liquid delivery pump 8, and the liquid storage tank 2 is provided with a vacuum generating means 10 for creating a negative pressure inside the liquid storage tank 2.
The cooling means 9 is composed of a heat exchanger equipped with a static mixer in the flow path of the outflow pipe 6, and cools the mixed fluid ML heated by friction in the shear dispersion means 4.
The vacuum generating means 10 creates a negative pressure inside the liquid storage tank 2, thereby removing air bubbles generated in the mixed fluid ML.

The downstream side of the outward pipe 6 is branched into a first branch pipe 6A and a second branch pipe 6B, and a first switching valve V1 is provided at the branching point to connect the outward pipe 6 to either the first branch pipe 6A or the second branch pipe 6B.
In addition, a first junction pipe 7A and a second junction pipe 7B join upstream of the return pipe 7, and a second switching valve V2 is provided at the junction to connect the return pipe 7 to either the first junction pipe 7A or the second junction pipe 7B.
The first branch pipe 6A is connected to the lower part of the solid-liquid mixing means 3, and the first junction pipe 7A is connected to the upper part.
The solid-liquid mixing means 3 is a conventionally known suction-type solid-liquid mixing device, and detailed explanation will be omitted; however, a rotor (not shown) is provided inside, and negative pressure is generated by high-speed rotation of the rotor, which sucks in the liquid L and powder P, thereby mixing the powder P with the liquid L.
In addition, a hopper 3a for holding powder P is provided above the solid-liquid mixing means 3, and two units of first and second quantitative supply feeders 11A and 11B for supplying powder P are provided above this hopper 3a.
The first and second quantitative supply feeders 11A, 11B are each capable of dropping a predetermined amount of powder P into the hopper 3a. By storing different types of powder in these feeders and varying the amount of powder supplied by each feeder, the two types of powder can be mixed into the liquid in the required ratio.
It is possible to operate only one of the constant-volume feeders to supply one type of powder, or three or more constant-volume feeders may be provided.
The hopper 3a receives the powder P that has fallen from the first and second quantitative supply feeders 11A and 11B, and a cylindrical chute 3b is provided at the bottom of the hopper 3a and is connected to the top of the solid-liquid mixing means 3 to supply the powder P.

As shown in FIG. 2, when the liquid L sent from the storage tank 2 to the outflow pipe 6 by the operation of the liquid feed pump 8 flows into the solid-liquid mixing means 3 from the first branch pipe 6A, the liquid L is sent at high speed by the rotation of the rotor, and negative pressure is generated inside the solid-liquid mixing means 3. This negative pressure causes the powder P to be sucked in through the chute 3b and mixed with the liquid L flowing through the solid-liquid mixing means 3.
The liquid L discharged from the solid-liquid mixing means 3 flows from the first junction pipe 7A through the return pipe 7 and returns to the storage tank 2. In this manner, the outward pipe 6, the first branch pipe 6A, the first junction pipe 7A, and the return pipe 7 form a first circulation path C1 for circulating the liquid L between the storage tank 2 and the solid-liquid mixing means 3.

Next, the second branch pipe 6B is connected to the upper part of the shear dispersion means 4, and the second junction pipe 7B is connected to the lower part.
The shear dispersion means 4 is a conventionally known shear type dispersion device and will not be described in detail, but a rotor 4a that rotates at high speed and a stator 4b that surrounds the rotor 4a are provided inside, and agglomerates (lumps) of the powder P in the mixed fluid ML are sheared in the gap between the rotor 4a and the stator 4b, thereby uniformly dispersing the powder P in the mixed fluid ML.
As shown in FIG. 3, a mixed fluid ML of a liquid L and a powder P is sent from the storage tank 2 to the outflow pipe 6 by the operation of the liquid feed pump 8, and flows into the upper part of the shear dispersion means 4 from the second branch pipe 6B, and the powder P is dispersed in the mixed fluid ML by the rotation of the rotor 4a.
The mixed fluid ML discharged from the shear dispersion means 4 flows through the second junction pipe 7B, and then flows into the return pipe 7 to return to the storage tank 2. In this manner, the outward pipe 6, the second branch pipe 6B, the second junction pipe 7B, and the return pipe 7 form the second circulation path C2, which circulates the mixed fluid ML between the storage tank 2 and the shear dispersion means 4.

The path switching means for switching between the first circulation path C1 and the circulation path C2 is composed of a first switching valve V1 provided in the outward pipe 6 and a second switching valve V2 provided in the return pipe 7. The first switching valve V1 and the second switching valve V2 are conventionally known three-way valves, and opening and closing thereof are controlled by the control means 5.
First, when forming the first circulation path C1 shown in FIG. 2, the first switching valve V1 connects the outward pipe 6 to the first branch pipe 6A, and the second switching valve V2 connects the return pipe 7 to the first junction pipe 7A, thereby forming a circulation path in which the storage tank 2 and the solid-liquid mixing means 3 are connected by the outward pipe 6, the first branch pipe 6A, the first junction pipe 7A, and the return pipe 7.
On the other hand, when forming the second circulation path C2 shown in Figure 3, the first switching valve V1 connects the outward pipe 6 to the second branch pipe 6B, and the second switching valve V2 connects the return pipe 7 to the second junction pipe 7B, thereby forming a circulation path in which the liquid storage tank 2 and the shear dispersion means 4 are connected by the outward pipe 6, the second branch pipe 6B, the second junction pipe 7B, and the return pipe 7.

Next, in the powder mixing and dispersion system 1 of this embodiment, when the powder P in the mixed fluid ML is dispersed by the shear dispersion means 4 to produce a slurry S (see Figure 4), the slurry S is discharged to a subsequent process not shown.
After use of the powder mixing and dispersion system 1, in order to clean the storage tank 2, the solid-liquid mixing means 3, and the shear dispersion means 4, a cleaning liquid CL (see Figures 6 and 7) is circulated through the outward pipe 6, the return pipe 7, the first and second branch pipes 6A, 6B, and the first and second junction pipes 7A, 7B, and this is discharged into a drainage tank or the like (not shown).
A discharge pipe 14 that branches off from the return pipe 7 and leads to a subsequent process is connected to the return pipe 7 at a position close to the storage tank 2, and a third switching valve V3 whose opening and closing is controlled by the control means 5 is provided at the connection position of the discharge pipe 14 on the return pipe 7.
In addition, a drain pipe 15 for discharging the cleaning liquid CL is branched off and connected to the discharge pipe 14, and a fourth switching valve V4 whose opening and closing is controlled by the control means 5 is provided at the connection point between the discharge pipe 14 and the drain pipe 15.

After dispersion and washing are completed, the entire amount of the slurry S and washing liquid CL contained in the liquid storage tank 2 is pumped by the liquid delivery pump 8 and discharged into the discharge pipe 14. However, when the liquid storage tank 2 becomes empty, the liquid delivery pump 8 can no longer deliver liquid thereafter.
As a result, the slurry S and the cleaning liquid CL end up remaining in the solid-liquid mixing means 3, the shear dispersion means 4, and further in the piping such as the forward pipe 6, the return pipe 7, the first and second branch pipes 6A and 6B, and the first and second junction pipes 7A and 7B. Therefore, in this embodiment, air is supplied to the forward pipe 6 to discharge the slurry S and the cleaning liquid CL remaining in these piping, etc.
An air supply pipe 16a of a gas supply means 16 consisting of a gas supply device such as a compressor is connected between the liquid delivery pump 8 and the cooling means 9 in the outward pipe 6, and a fifth switching valve V5 whose opening and closing is controlled by the control means 5 is provided at the connection point between the outward pipe 6 and the air supply pipe 16a.
As a result, gas is supplied from the gas supply means 16 to the outflow pipe 6 to send gas in the liquid sending direction of the liquid sending pump 8, and the slurry S and cleaning liquid CL remaining in the above-mentioned piping, etc. are pressure-fed and discharged from the discharge pipe 14.
In addition, a liquid-out sensor 18 is provided in the discharge pipe 14 before the fourth switching valve V4, which detects whether or not the slurry S or the cleaning liquid CL is flowing, and detects when the flow of the slurry S or the cleaning liquid CL is interrupted and sends the result to the control means 5.

Furthermore, the first branch pipe 6A and the first junction pipe 7A are connected by a bypass pipe 21, and a sixth switching valve V6 is provided at the connection position between the first branch pipe 6A and the bypass pipe 21, and a seventh switching valve V7 is provided at the connection position between the first junction pipe 7A and the bypass pipe 21.
The first branch pipe 6A and the first junction pipe 7A are connected to each other via the bypass pipe 21 through the sixth switching valve V6 and the seventh switching valve V7, thereby forming a third circulation path C3 (see FIG. 11 ) consisting of the outward pipe 6, the first branch pipe 6A, the bypass pipe 21, the first junction pipe 7A, and the return pipe 7.
Since the third circulation path C3 is used in the second embodiment described later, in the description of the operation of the first embodiment described below, the sixth switching valve V6 and the seventh switching valve V7 do not block the flow of the first branch pipe 6A and the first junction pipe 7A.

The operation of the powder mixing and dispersing system 1 having the above configuration will be described below.
First, FIG. 2 shows a circulatory mixing step in which liquid L is circulated between the storage tank 2 and the solid-liquid mixing means 3 while mixing the liquid L with powder P to produce a mixed fluid ML.
At this time, a predetermined amount of liquid L is stored in the liquid storage tank 2 in advance, and the forward pipe 6 and the return pipe 7 are connected to the solid-liquid mixing means 3 via the first branch pipe 6A and the first junction pipe 7A by the first and second switching valves V1 and V2 serving as the path switching means, thereby forming the first circulation path C1.
In this state, when the liquid sending pump 8 provided in the outflow pipe 6 is operated, the liquid L in the liquid storage tank 2 flows from the outflow pipe 6 through the first branch pipe 6A into the solid-liquid mixing means 3.
In the solid-liquid mixing means 3, a predetermined amount of powder P is dropped into the hopper 3a from the first and second constant-volume feeders 11A and 11B.
Negative pressure is generated inside the solid-liquid mixing means 3 by the rotation of the rotor, and the powder P is sucked from the hopper 3a through the chute 3b, whereby the powder is mixed with the flowing liquid L to become a mixed fluid ML.
The mixed fluid ML discharged from the solid-liquid mixing means 3 flows through the return pipe 7 via the first junction pipe 7A and is returned to the liquid storage tank 2, and the control means 5, based on the settings, continues to operate the liquid delivery pump 8 for a predetermined time even after all the powder in the hopper 3a has been sucked up, circulating the mixed fluid ML through the first circulation path C1 a predetermined number of times to promote mixing of the powder in the mixed fluid ML. As a result, the mixed fluid ML in which the solid particles of the powder P are suspended in the liquid L to form a slurry is stored in the liquid storage tank 2.
In this way, a predetermined amount of powder P, which has been measured using a constant-volume feeder and then stored in the hopper 3a, and a predetermined amount of liquid L, which has been measured in advance and stored in the liquid storage tank 2, are mixed while circulating using the solid-liquid mixing means 3, so that the liquid and powder can be mixed precisely in specified amounts.

Next, FIG. 3 shows a circulating dispersion process in which the mixed fluid ML is circulated between the storage tank 2 and the shear dispersion means 4 to uniformly disperse the powder P in the mixed fluid ML.
The control means 5 controls the first and second switching valves V1, V2 serving as the path switching means, thereby blocking the communication between the outward pipe 6 and the first branch pipe 6A and connecting the outward pipe 6 to the second branch pipe 6B, and blocking the communication between the first junction pipe 7A and the return pipe 7 and connecting the second junction pipe 7B to the outward pipe 7, thereby connecting the liquid storage tank 2 to the shear dispersion means 4 and forming the second circulation path C2.
The liquid delivery pump 8 provided in the forward pipe 6 continues to operate, and when the mixed fluid ML in the storage tank 2 mixed in the circulating mixing process flows into the shear dispersion means 4 via the forward pipe 6 and the second branch pipe 6B, the powder P is dispersed by shearing in the gap between the rotor 4a and the stator 4b.
The mixed fluid ML discharged from the shear dispersion means 4 then flows from the second junction pipe 7B into the return pipe 7 and is returned to the storage tank 2, and the control means 5, based on the settings, continues to operate the liquid delivery pump 8 for a predetermined time to circulate the mixed fluid ML through the second circulation path C2 a predetermined number of times, thereby obtaining a slurry S in which the powder is uniformly dispersed.
Here, when the mixed fluid ML is sheared by the shear dispersion means 4, the mixed fluid ML is heated by frictional heat. Therefore, while the mixed fluid ML is circulated through the second circulation path C2, it is constantly cooled by the cooling means 9 provided in the outward pipe 6.
During the time when the mixed fluid ML is circulated through the second circulation path C2, the vacuum generating means 10 provided in the liquid storage tank 2 is operated to remove air bubbles generated in the mixed fluid ML.

Next, FIG. 4 shows a discharge process in which the obtained slurry S is discharged to a subsequent process of the powder mixing and dispersing system 1.
The control means 5, from a state in which a second circulation path C2 connecting the storage tank 2 and the shear dispersion means 4 has been formed, operates the third switching valve V3 provided on the return pipe 7 to block the connection between the return pipe 7 and the storage tank 2 and connect the return pipe 7 to the discharge pipe 14.
As a result, the slurry S in the storage tank 2 flows through the same route as the second circulation route C2 which flows into the shear dispersion means 4 via the outward pipe 6 and the second branch pipe 6B, and then the slurry S flows from the second junction pipe 7B into the return pipe 7, and further flows through the discharge pipe 14 to be discharged to the downstream equipment.
In the discharging step of this embodiment, discharging is not performed from the solid-liquid mixing means 3 .
This is because there is a risk that the powder P sucked from the hopper 3a may remain in the solid-liquid mixing means 3 without being sufficiently mixed, and in order to prevent such powder P from being mixed into the slurry S after dispersion has been completed, in this embodiment, the residue in the solid-liquid mixing means 3 is not recovered and is not sent to a subsequent process.

FIG. 5 shows a residual liquid removing step for removing the slurry S remaining in the piping and the like.
After stopping the liquid delivery pump 8, the control means 5 operates the fifth switching valve V5 from the state of the dispensing process shown in Figure 4 to block the flow path leading to the liquid delivery pump 8, connect the air supply pipe 16a to the outward pipe 6, and supply gas from the gas supply means 16 to the outward pipe 6 via the air supply pipe 16a.
The gas supplied to the outward pipe 6 passes through the cooling means 9 while pushing the remaining slurry S, and flows from the first switching valve V1 into the second branch pipe 6B, and then pushes the slurry S remaining in the second branch pipe 6B, the shear dispersion means 4, and the second junction pipe 7B, and flows from the second switching valve V2 into the return pipe 7. The slurry S pushed by the gas is then pushed out from the third switching valve V3 into the discharge pipe 14, and sent to the next process.
When all of the slurry S remaining in the piping, etc. is pushed out into the discharge pipe 14 and gas begins to flow through the discharge pipe 14, the liquid-out sensor 18 detects that the slurry S has been interrupted, and the control means 5 switches the fifth switching valve V5 to stop the supply of gas to the outbound pipe 6 by the gas supply means 16.
The gas supplied by the gas supply means 16 may be air or nitrogen if the slurry S is sensitive to oxidation.

6 to 9 show a cleaning and drying process in which the piping and the like constituting the powder mixing and dispersing system 1 are cleaned and dried after the residual liquid dispensing process in which the slurry S is dispensed is completed.
FIG. 6 shows the operation of cleaning the solid-liquid mixing means 3, in other words, the cleaning liquid CL is caused to flow through the first circulation path C1 to clean it.
Before the washing and drying process, a cleaning liquid CL is supplied in advance to the liquid storage tank 2. When a food such as wheat flour is dispersed in water, water is used as the cleaning liquid CL, and when an inorganic material is dispersed in a solvent such as an organic solvent, a required solvent can be used as the cleaning liquid CL, and NMP is used in this embodiment.
The control means 5 switches the first switching valve V1 and the second switching valve V2 serving as the path switching means as in the circulating mixing process shown in FIG. 2 to connect the storage tank 2 to the solid-liquid mixing means 3 via the outward pipe 6 and the first branch pipe 6A, and also connects the solid-liquid mixing means 3 to the return pipe 7 via the first junction pipe 7A.
However, the control means 5 uses the third switching valve V3 to not connect the return pipe 7 to the storage tank 2 but maintains its connection to the discharge pipe 14, and further uses the fourth switching valve V4 provided in the discharge pipe 14 to block flow from the discharge pipe 14 to the next process and connect the discharge pipe 14 to the drain pipe 15.
In this state, by operating the liquid delivery pump 8, the cleaning liquid CL in the liquid storage tank 2 flows through the outflow pipe 6, passes through the cooling means 9, and flows into the solid-liquid mixing means 3 via the first branch pipe 6A.
Thereafter, the cleaning liquid CL flows from the solid-liquid mixing means 3 through the first junction pipe 7A into the return pipe 7, flows through the third switching valve V3 into the discharge pipe 14, and then flows through the fourth switching valve V4 into the drain pipe 15 and is discharged into a waste liquid tank (not shown).
In addition, before and after rinsing the solid-liquid mixing means 3 and the piping connected thereto as described above, the return pipe 7 may be connected to the liquid storage tank 2 by the third switching valve V3 to form a first circulation path C1, and the cleaning liquid CL may be circulated from the liquid storage tank 2, thereby cleaning the return pipe 7 between the third switching valve V3 and the liquid storage tank 2 as well as the liquid storage tank 2.

FIG. 7 shows the subsequent operation of cleaning the shear dispersion means 4. In other words, the cleaning liquid CL is caused to flow through the second circulation path C2 to clean it.
The control means 5 switches the first switching valve V1 and the second switching valve V2 serving as the path switching means from the state shown in Figure 6 to the circulating dispersion process shown in Figure 3, thereby connecting the outward pipe 6 to the second branch pipe 6B to connect the liquid storage tank 2 to the shear dispersion means 4, and also connects the second junction pipe 7B to the return pipe 7, and further connects the return pipe 7 to the discharge pipe 14 by the third switching valve V3.
As a result, the cleaning liquid CL in the storage tank 2 flows into the shear dispersion means 4 via the outward pipe 6 and the second branch pipe 6B, and the cleaning liquid CL further flows through the return pipe 7 via the second junction pipe 7B, and then flows through the discharge pipe 14 and the drain pipe 15 to be discharged into the waste liquid tank.

FIG. 8 shows an operation for discharging the cleaning liquid CL remaining after cleaning from the outward pipe 6, the first branch pipe 6A, the first junction pipe 7A, the return pipe 7 and the solid-liquid mixing means 3, and drying them.
When the cleaning liquid CL in the storage tank 2 is emptied and the cleaning operation is completed, the control means 5 stops the liquid supply pump 8 and switches the first and second switching valves V1, V2 as path switching means in the same manner as in the cleaning operation shown in Figure 6, thereby connecting the outbound pipe 6 to the first branch pipe 6A and connecting the return pipe 7 to the first junction pipe 7A.
In addition, the third switching valve V3 maintains communication between the return pipe 7 and the discharge pipe 14, and the fifth switching valve V5 provided in the outward pipe 6 blocks communication with the liquid delivery pump 8, connects the outward pipe 6 to the air supply pipe 16a, and supplies gas to the outward pipe 6 by the gas supply means 16.
As a result, the gas supplied from the gas supply means 16 flows into the solid-liquid mixing means 3 via the forward pipe 6 and the first branch pipe 6A while pushing the remaining cleaning liquid CL, and then passes through the first junction pipe 7A and the return pipe 7 to push the cleaning liquid CL out into the discharge pipe 14, and then out of the drain pipe 15.
Then, when the liquid shortage sensor 18 detects that the flow of the cleaning liquid CL has been interrupted, the gas supply means 16 continues to supply gas for a predetermined period of time, thereby drying the solid-liquid mixing means 3, the first branch pipe 6A, and the first junction pipe 7A.
Furthermore, before and after the residual liquid discharge and drying operations, the third switching valve V3 is switched to connect the discharge pipe 14 to the storage tank 2, and the fifth switching valve V5 is switched to connect the air supply pipe 16a to the liquid delivery pump 8 and the storage tank 2, so that gas is circulated from the gas supply means 16 through the liquid delivery pump 8 and the storage tank 2 to the discharge pipe 14 and discharged from the drain pipe 15, thereby drying the forward pipe 6 between the fifth switching valve V5 and the storage tank 2, the return pipe 7 between the third switching valve V3 and the storage tank 2, the inside of the storage tank 2, and the liquid delivery pump 8.

FIG. 9 shows the operation of discharging the cleaning liquid CL from the second branch pipe 6B, the second junction pipe 7B and the shear dispersion means 4 and drying them.
The control means 5 continues from the state shown in Figure 8 and switches the first and second switching valves V1, V2 serving as the above-mentioned path switching means, connecting the outward pipe 6 to the second branch pipe 6B to connect the gas supply means 16 to the shear dispersion means 4, and connecting the second junction pipe 7B to the return pipe 7 to connect the shear dispersion means 4 to the exhaust pipe 14.
As a result, the gas supplied from the gas supply means 16 flows into the shear dispersion means 4 via the outflow pipe 6 and the second branch pipe 6B, and discharges the remaining cleaning liquid CL.
Furthermore, the gas flows into the return pipe 7 via the second junction pipe 7B, and pushes the cleaning liquid CL into the discharge pipe 14, causing it to be discharged from the drain pipe 15.
Thereafter, when the liquid shortage sensor 18 detects that the flow of the cleaning liquid CL has been interrupted, the gas supply means 16 continues to supply gas for a further predetermined period of time, thereby drying the forward pipe 6, the return pipe 7, the shear dispersion means 4, the second branch pipe 6B, and the second junction pipe 7B.

In this way, according to the powder dispersion system 1 of this embodiment, first, the liquid L is circulated using the first circulation path C1, and then the powder P is mixed into the liquid L by the solid-liquid mixing means 3 to form a mixed fluid ML, so that the powder P can be sufficiently mixed into the liquid L to form the mixed fluid ML, and the occurrence of powder agglomerates can be suppressed as much as possible.
Thereafter, while circulating the mixed fluid ML mixed with the powder P through the second circulation path C2, the powder P is uniformly dispersed in the mixed fluid ML by the shear dispersion means 4. At this time, since the powder P is sufficiently mixed in the mixed fluid ML by circulating the mixed fluid ML through the first circulation path C1, it is possible to efficiently obtain a slurry S in which the powder P is uniformly dispersed by dispersing the powder P using the shear dispersion means 4 while circulating the mixed fluid ML through the second circulation path C2 a predetermined number of times.
In addition, the first circulation path C1 and the second circulation path C2 share the forward pipe 6 and the return pipe 7 connected to the liquid storage tank 2, and a path switching means is used to switch the communication between the liquid storage tank 2 and the solid-liquid mixing means 3 or the shear dispersion means 4 to form a circulation path.
As a result, compared to the case where a circulation path is formed so that the solid-liquid mixing means 3 and the shear dispersion means 4 are individually connected to the liquid storage tank 2, the amount of piping used is reduced and the system can be configured compactly. Also, the amount of slurry S remaining in the piping is small, the dispensing time is shortened, and the amount of cleaning liquid CL used can be reduced.

10 to 15 are diagrams for explaining the powder mixing and dispersing system 1 according to the second embodiment using the third circulation path C3. Note that detailed explanations of the configuration and operation of the second embodiment common to the first embodiment will be omitted.
As described above, the powder mixing and dispersing system 1 of this embodiment is provided with the bypass pipe 21 between the first branch pipe 6A and the first junction pipe 7A.
In addition, sixth and seventh switching valves V6, V7 serving as bypass switching means are provided at the connection positions of the first branch pipe 6A and the first junction pipe 7A with the bypass pipe 21, respectively, and their opening and closing are controlled by the control means 5.
As a result, a third circulation path C3 that exits the storage tank 2 and returns to the storage tank 2 is formed by the outbound pipe 6, a portion of the first branch pipe 6A, the bypass pipe 21, a portion of the first junction pipe 7A, and the return pipe 7.
The mixed fluid ML contained in the storage tank 2 is sent by the liquid sending pump 8 , and then circulates through the bypass pipe 21 and then circulates to the storage tank 2 .
In addition, the powder mixing and dispersing system 1 of the first embodiment shown in Figures 1 to 9 also has the bypass pipe 21 and the sixth and seventh switching valves V6, V7, but these can be omitted in the first embodiment.

The operation of the powder mixing and dispersing system 1 according to the second embodiment will be described below. In the first embodiment, the powder P in the mixed fluid ML is uniformly dispersed in the circulating and dispersing step, and then the mixed fluid ML is sent to the subsequent step as a slurry S. However, in the second embodiment, a stabilizing step is performed after the circulating and dispersing step, and the mixed fluid ML in which the powder P is uniformly dispersed is stabilized, and then the mixed fluid ML is sent to the subsequent step as a slurry S.
First, FIG. 10 shows an operation after the completion of the circulating dispersion process shown in FIG. 3 in the first embodiment, and shows a process of recovering the mixed fluid ML remaining in the second circulating path C2, particularly the second branch pipe 6B, the shear dispersion means 4, and the second junction pipe 7B, into the liquid storage tank 2.
That is, in the second embodiment as well, the circulatory mixing process using the first circulation path C1 shown in FIG. 2 and the circulatory dispersion process using the second circulation path C2 shown in FIG. 3 described in the first embodiment are performed, and a mixed fluid ML in which the powder P is dispersed in the liquid L is produced.
In the above-mentioned circulating dispersion process, the mixed fluid ML is circulated through the second circulation path C2 and the powder P is dispersed by the shear dispersion means 4. As a result, the mixed fluid ML in which the powder P is uniformly dispersed remains in the second branch pipe 6B, the shear dispersion means 4, and the second junction pipe 7B that constitute the second circulation path C2.
Therefore, the control means 5 operates the fifth switching valve V5 provided in the outward pipe 6 from the state in which the second circulation path C2 shown in Figure 3 is formed, and connects the outward pipe 6 to the gas supply means 16.
In this state, when gas is supplied from the gas supply means 16, the gas flows from the outflow pipe 6 into the second branch pipe 6B and into the shear dispersion means 4, and then flows through the second junction pipe 7B and into the liquid storage tank 2 from the outflow pipe 7.
This makes it possible to push out the mixed fluid ML remaining in the outward pipe 6, the return pipe 7, and the second branch pipe 6B through the circulating dispersion means 4 to the second junction pipe 7B, and recover this in the storage tank 2.

FIG. 11 shows a stabilization step for stabilizing the mixed fluid ML that has been subjected to the dispersion treatment by the shear dispersion means 4.
As described above, when the mixed fluid ML is circulated in the second circulation path C2 and sheared by the shear dispersion means 4, the mixed fluid ML is heated due to friction and air bubbles are generated in the mixed fluid ML.
Therefore, in the second embodiment, the mixed fluid ML is circulated through the third circulation path C3, thereby cooling the mixed fluid ML and removing air bubbles, and the mixed fluid ML is stabilized and sent to the subsequent process as a slurry S.
That is, from the state shown in Figure 10, the control means 5 uses the first and second switching valves V1, V2 as route switching means to disconnect the communication between the outward pipe 6 and the second branch pipe 6B and connect them to the first branch pipe 6A, and disconnect the communication between the return pipe 7 and the second junction pipe 7B and connect them to the first junction pipe 7A, and further operate the fifth switching valve V5 to disconnect the connection between the outward pipe 6 and the gas supply means 16.
Furthermore, the control means 5 operates the sixth and seventh switching valves V6, V7 serving as the bypass switching means to communicate the first branch pipe 6A and the first junction pipe 7A through the bypass pipe 21. This forms a circulation path through which the mixed fluid ML leaves the liquid storage tank 2 and returns to the liquid storage tank 2 without passing through either the solid-liquid mixing means 3 or the shear dispersion means 4. In the piping configuration in the second embodiment, the first and second switching valves V1, V2 together constitute the bypass switching means.
When the liquid feed pump 8 is operated in this state, the mixed fluid ML flowing out from the storage tank 2 to the outward pipe 6 flows through the first branch pipe 6A, the bypass pipe 21, and the first junction pipe 7A, and flows into the return pipe 7, and circulates through the third circulation path that flows into the storage tank 2 without passing through the solid-liquid mixing means 3 and the shear dispersion means 4, during which the mixed fluid ML is cooled by the cooling means 9, and further, air bubbles in the mixed fluid ML are removed within the storage tank 2 by the vacuum generating means 10.
The control means 5 maintains this state for a predetermined period of time, whereby the mixed fluid ML is cooled and defoamed and deaerated, so that a slurry S in a stable state is obtained.

Next, FIG. 12 shows a discharge process in which the slurry S obtained by stabilizing the mixed fluid ML is discharged to a subsequent process of the powder mixing and dispersing system 1.
The control means 5 operates the third switching valve V3 provided in the return pipe 7 from the state of FIG. 11 in which the mixed fluid ML is circulated through the third circulation path C3, to connect the return pipe 7 to the discharge pipe 14.
As a result, the slurry S in the storage tank 2 flows through the forward pipe 6 by operation of the liquid transfer pump 8, flows from the first branch pipe 6A through the bypass pipe 21 into the first junction pipe 7A, and then flows through the return pipe 7 and is discharged from the discharge pipe 14 to the subsequent process.

FIG. 13 shows a residual liquid dispensing step in which the slurry S remaining in the piping downstream of the liquid feed pump 8 is dispensing after the dispensing step shown in FIG.
The control means 5 operates the fifth switching valve V5 from the state shown in FIG. 12 to connect the gas supply means 16 to the outward pipe 6, and supplies gas from the gas supply means 16 to the outward pipe 6.
As a result, the slurry S remaining in the outward pipe 6 is pushed by the gas, flows from the first branch pipe 6A through the bypass pipe 21 and the first junction pipe 7A, and then flows through the return pipe 7 and is discharged into the discharge pipe 14.
In addition, when all of the slurry S remaining in the piping, etc. is discharged and gas flows into the exhaust pipe 14, the liquid shortage sensor 18 detects the liquid shortage, and the control means 5 switches the fifth switching valve V5 to stop the supply of gas by the gas supply means 16.

14 and 15 show the operations of cleaning the third circulation path C3, discharging the cleaning liquid CL, and drying, which are performed in addition to the cleaning and drying process described in FIGS. 6 to 9 in the first embodiment.
First, FIG. 14 shows a state in which the third circulation path C3 is cleaned, which is carried out after the second circulation path C2 shown in FIG. 7 in the first embodiment is cleaned.
7 is completed, the control means 5 controls the first and second switching valves V1 and V2 as the path switching means to release the communication between the outward pipe 6 and the second branch pipe 6B and connect them to the first branch pipe 6A, and release the communication between the return pipe 7 and the second junction pipe 7B and connect them to the first junction pipe 7A. Also, the sixth and seventh switching valves V6 and V7 as the bypass switching means control the first branch pipe 6A and the first junction pipe 7A to communicate with each other via the bypass pipe 21.
By operating the liquid supply pump 8 in this state, the cleaning liquid CL flowing out of the liquid storage tank 2 flows through the forward pipe 6 and the first branch pipe 6A, and then flows from the bypass pipe 21 into the first junction pipe 7A, and then flows from the return pipe 7 into the discharge pipe 14, and is discharged from the drain pipe 15 to a waste liquid tank not shown, thereby cleaning the bypass pipe 21.

Next, FIG. 15 shows the operation of discharging the cleaning liquid CL in the third circulation path C3 and drying it, which is carried out after the step shown in FIG. 9 in the first embodiment.
9 is completed, the control means 5 operates the first and second switching valves V1, V2 as the above-mentioned path switching means to release the communication between the outward pipe 6 and the second branch pipe 6B and connect them to the first branch pipe 6A, and release the communication between the return pipe 7 and the second junction pipe 7B and connect them to the first junction pipe 7A. Also, the control means 5 operates the sixth and seventh switching valves V6, V7 as the above-mentioned bypass switching means to connect the first branch pipe 6A and the first junction pipe 7A through the bypass pipe 21.
In this state, gas is supplied from the air supply means 16 via the fifth switching valve V5. The gas supplied from the air supply pipe 16a flows through the outgoing pipe 6 and the first branch pipe 6A, flows from the bypass pipe 21 into the first junction pipe 7A and the return pipe 7, and then flows from the return pipe 7 into the discharge pipe 14 and is discharged from the drain pipe 15 to a waste liquid tank (not shown), thereby drying the bypass pipe 21.

As described above, according to the second embodiment, the liquid L is circulated through the first circulation path C1 while being mixed with the powder P to form a mixed fluid ML, the mixed fluid ML is circulated through the second circulation path C2 to disperse the powder P, and then the mixed fluid ML is circulated through the third circulation path C3, thereby making it possible to obtain a stabilized slurry S.
In the above description, the first branch pipe 6A and the first junction pipe 7A are connected by the bypass pipe 21 to form the third circulation path C3, and the sixth switch valve V6 is provided in the first branch pipe 6A and the seventh switch valve V7 is provided in the first junction pipe 7A to form the bypass switching means. However, it is also possible to connect the second branch pipe 6B and the second junction pipe 7B by the bypass pipe 21 to form the third circulation path C3, and to provide the sixth switch valve V6 in the second branch pipe 6B and the seventh switch valve V7 in the second junction pipe 7B to form the bypass switching means. Furthermore, it is also possible to connect the outward pipe 6 and the return pipe 7 by the bypass pipe 21 to form the third circulation path C3, and to provide the sixth switch valve V6 in the outward pipe 6 and the seventh switch valve V7 in the return pipe 7 to form the bypass switching means.
There are other possible patterns for providing the bypass pipe 21, but the point is that it is sufficient if the mixed fluid ML can be circulated so that it leaves the liquid storage tank 2 and returns to the liquid storage tank 2 without passing through either the solid-liquid mixing means 3 or the shear dispersion means 4.
In addition, the third circulation path C3 shares the forward pipe 6 and the return pipe 7 connected to the storage tank 2 with the first circulation path C1 and the second circulation path C2, and compared to the case where the third circulation path C3 is provided alone, the amount of piping used is reduced and the system can be configured compactly. Also, the amount of residual slurry S is small, so that the dispensing time is short, and the amount of cleaning liquid CL used can be reduced.

REFERENCE SIGNS LIST 1 Powder mixing and dispersion system 2 Liquid storage tank 3 Solid-liquid mixing means 4 Shear dispersion means 5 Control means 6 Outward pipe 6A First branch pipe 6B Second branch pipe 7 Return pipe 7A First junction pipe 7B Second junction pipe 8 Liquid delivery pump 9 Cooling means 14 Discharge pipe 15 Discharge pipe 16 Gas supply means 16a Air supply pipe 21 Bypass pipe C1 First circulation path C2 Second circulation path C3 Third circulation path
V1: First switching valve (path switching means) V2: Second switching valve (path switching means)
V3: third switching valve V5: fifth switching valve V6: sixth switching valve (bypass switching means)
V7 Seventh switching valve (bypass switching means)
P Powder L Liquid ML Mixed fluid CL Cleaning liquid S Slurry

Claims (3)

A powder mixing and dispersing system including a liquid storage tank for storing a liquid and a shear dispersing means for dispersing powder mixed in the liquid by shear,
the liquid storage tank and the solid-liquid mixing means; a first circulation path for circulating the liquid between the liquid storage tank and the solid-liquid mixing means; a second circulation path for circulating a mixed fluid of liquid and powder between the liquid storage tank and the shear dispersion means; a third circulation path for circulating the mixed fluid from the liquid storage tank to the liquid storage tank without passing through either the solid-liquid mixing means or the shear dispersion means; a path switching means for switching between the first circulation path and the second circulation path ; and a bypass switching means for switching between the second circulation path and the third circulation path ,
a powder mixing and dispersion system comprising: a liquid circulating between a liquid storage tank and a solid-liquid mixing means through the first circulation path while mixing a powder into the liquid to store the liquid as a mixed fluid in the liquid storage tank; then, the path switching means switches from the first circulation path to the second circulation path, and the mixed fluid stored in the liquid storage tank is circulated between the liquid storage tank and the shear dispersion means through the second circulation path while dispersing the powder in the mixed fluid; then, the bypass switching means switches from the second circulation path to a third circulation path, and the mixed fluid in which the powder has been dispersed is circulated through the third circulation path . a forward pipe for sending out liquid or the mixed fluid from the storage tank, a return pipe for returning the liquid or the mixed fluid to the storage tank, a first branch pipe connected to the forward pipe for sending liquid from the forward pipe to the solid-liquid mixing means, a first junction pipe connected to the return pipe for sending liquid from the solid-liquid mixing means to the return pipe, a second branch pipe connected to the forward pipe for sending the mixed fluid from the forward pipe to the shear dispersion means, a second junction pipe connected to the return pipe for sending the mixed fluid from the shear dispersion means to the return pipe, a first switching means for connecting either the first branch pipe or the second branch pipe to the forward pipe, and a second switching means for connecting either the first junction pipe or the second junction pipe to the return pipe,
The powder mixing and dispersion system according to claim 1, characterized in that the first circulation path is formed by the forward pipe and the return pipe, the first branch pipe and the first junction pipe, the second circulation path is formed by the forward pipe and the return pipe, the second branch pipe and the second junction pipe, and the path switching means is formed by the first switching means and the second switching means. 3. The powder mixing and dispersion system according to claim 2, characterized in that the forward pipe is provided with a liquid delivery pump for delivering liquid and the mixed fluid from the storage tank, and an air supply pipe of a gas supply means is connected to the downstream side of the liquid delivery pump of the forward pipe so that gas can be supplied to the forward pipe.