JP7469551B1 - Degassing System - Google Patents

Abstract

[Problem] To provide a degassing system that can more reliably degas highly viscous liquids. [Solution] The system includes a tank 3 that stores a viscous liquid, a pump 6 that exhausts gas from inside the tank 3, and a control device 7 that controls the pump 6. The control device 7 sets the liquid level inside the tank 3 when the pump 6 is stopped as a reference liquid level, operates the pump 6 to exhaust the gas from the tank 3 to form a foamy layer on top of the viscous liquid, controls the amount of exhaust by the pump 6 so that the liquid level of the foamy layer remains constant, and continues exhaust by the pump until the foamy layer shrinks to the reference liquid level. [Selected Figure] Figure 1

Description

The present invention relates to a degassing system for degassing highly viscous liquids.

Liquid products such as medicines, beverages, and inks may require degassing of dissolved gas during the manufacturing process. Liquid products with high viscosity require a long time to degas naturally while stored in a tank, so various degassing methods have been investigated. For example, a method is known in which the liquid product is degassed by repeatedly venting gas from a tank storing the liquid product and then stopping the venting (see Patent Document 1).

However, because the pumping and stopping is repeated, it takes longer to degas the tank, and more energy is required to start and stop the pump.

JP 2002-113303 A

In view of these circumstances, the present invention aims to provide a degassing system capable of degassing viscous liquids.

A first aspect for achieving the above-mentioned object is a degassing system for degassing a viscous liquid having dissolved therein gas, comprising a tank for storing the viscous liquid, a pump for evacuating the gas inside the tank, and a control device for controlling the pump, wherein the control device sets the liquid level inside the tank when the pump is stopped as a reference liquid level, operates the pump to evacuate the gas from the tank to form a foamy layer on top of the viscous liquid, controls the amount of exhaust by the pump so that the liquid level of the foamy layer remains constant, and stops exhausting by the pump when the foamy layer shrinks to the reference liquid level despite the pump evacuating the gas from the tank .

The present invention provides a degassing system capable of degassing viscous liquids.

1 is a schematic diagram of a degassing system according to a first embodiment. FIG. FIG. 1 is a diagram showing a viscous liquid stored inside a tank. 1 is a graph showing the change in the liquid level _L1 of the foam layer and the amount of displacement by the pump. FIG. FIG. 11 is a schematic diagram showing a tank of a degassing system according to a second embodiment. FIG. 11 is a schematic diagram showing a state in which a tank in a degassing system according to a second embodiment is used. FIG. 11 is a schematic diagram showing a degassing system according to a third embodiment.

First Embodiment
1 is a schematic diagram of a degassing system 1. The degassing system 1 of the present embodiment includes a raw material supplying means 2, a tank 3, a liquid level gauge 5, an agitator 4, a pump 6, and a controller 7, and is a system for producing and degassing a viscous liquid.

A viscous liquid is a liquid that has gas dissolved in it and has a viscosity that causes bubbles to form when stirred or placed in a vacuum, as described below. The viscosity is about 3,000 to 60,000 mPa·s. Examples of viscous liquids include liquid medicines, foods, beverages, and ink.

The raw material supplying means 2 is a group of devices that supply viscous liquid raw materials to the tank 3. The raw material supplying means 2 is composed of containers that hold a single raw material or two or more raw materials, piping that connects the containers to the tank 3, a valve that adjusts the opening of the piping, a pump that vacuums and transfers the raw materials from the containers to the tank 3, and the like. The raw material supplying means 2 is also configured to supply the raw materials to the tank 3 at a predetermined flow rate in response to a control signal from the control device 7, which will be described later.

The tank 3 is a container that receives raw materials from the raw material supply means 2 and stores the viscous liquid produced from the raw materials. The tank 3 is equipped with a stirring device 4. The stirring device 4 is a device that stirs the raw materials supplied to the tank 3. The multiple types of raw materials supplied from the raw material supply means 2 are stirred by the stirring device 4 to produce a viscous liquid.

Although not specifically shown, the tank 3 is provided with an openable opening at the bottom of the tank 3 and piping connected to the opening, etc., as a configuration for transferring the stored viscous liquid to other tanks or devices. The viscous liquid can be transferred to other tanks or devices by a control signal from the control device 7.

The level gauge 5 is a device that measures the height of the viscous liquid stored in the tank 3. The height of the liquid level is the height of the viscous liquid based on the bottom of the tank 3. Various types of level gauges can be used as the level gauge 5. Examples include laser type, ultrasonic type, capacitance type, radio wave type, pressure type, and float type. In particular, it is preferable to use a laser type level gauge 5. The height of the liquid level measured by the level gauge 5 is transmitted to the control device 7.

The pump 6 is attached to the tank 3 so as to exhaust the gas inside the tank 3. When the pump 6 is operated, the inside of the tank 3 becomes negative pressure, and when the pump 6 is stopped, the inside of the tank 3 returns to normal pressure. The pump 6 is configured to operate, stop, or change its output in response to a control signal from the control device 7.

The control device 7 is also called a programmable controller (PLC) or sequencer. The control device 7 has a CPU and memory, and reads and executes a control program stored in the memory to obtain the liquid level from the liquid level gauge 5 and control the raw material supply means 2, the agitator 4, and the pump 6.

Specific control by the control device 7 will be described with reference to Figures 2 and 3. Figure 2 shows the viscous liquid stored inside the tank, and Figure 3 shows the liquid level _L1 of the foam layer and the transition of the amount of gas discharged by the pump. The amount of gas discharged outside the tank 3 (the gas originally in the tank 3 and the gas contained in the viscous liquid) is called the amount of gas discharged. The horizontal axis of Figure 3 shows the elapsed time from the start of degassing. The amount of gas discharged in Figure 3 shows the cumulative amount from the start of degassing.

As shown in Fig. 2(a), the control device 7 controls the raw material supply means 2 to supply various raw materials to the tank 3. The inside of the tank 3 is at normal pressure, and the liquid level of the viscous liquid in this state is set as the reference liquid level _L0 . After the raw materials are supplied, the control device 7 operates the pump 6 (time _T0 in Fig. 3) to create a negative pressure inside the tank 3.

As shown in FIG. 2B, when the inside of the tank 3 is subjected to negative pressure, a foamy layer B is formed on the top of the viscous liquid A. The foamy layer B refers to the viscous liquid that has become foamy. As shown between time _T0 and time _T1 in FIG. 3, the liquid level _L1 of the foamy layer B gradually increases. The foamy layer B refers to a portion that is higher than the liquid level of the viscous liquid A at normal pressure. The foamy layer B is a gas dissolved in the viscous liquid A that is made visible by the negative pressure, but as shown in FIG. 2B, the interface between the foamy layer B and the viscous liquid A is not necessarily clear, and there may be cases where there are almost no bubbles in the portion of the foamy layer B near the interface with the viscous liquid A.

The amount of discharged liquid from the inside of the tank 3 to the outside by the pump 6 and the time from time _T0 to time _T1 are set so that a foamy layer B at the liquid level _L2 is formed. The liquid level _L2 of the foamy layer B to be kept constant is set to a level that can be seen through a sight glass or the like (for example, about several cm), or to a level where the liquid level _L2 of the foamy layer B detected by the liquid level gauge 5 can be distinguished from the reference liquid level _L0 (outside the error range of the liquid level gauge 5). The pump 6 is operated so that the liquid level _L2 becomes the target liquid level. If the amount of discharged liquid per unit time by the pump 6 is large, the time will be short, and if the amount of discharged liquid is small, the time will be long. In any case, if the amount of discharged liquid per unit time is appropriately set and discharge is continued from time _T0 to time _T1 , a negative pressure sufficient to form a foamy layer B at the liquid level _L2 is generated in the tank 3.

When the liquid level _L1 of the foam layer B reaches the liquid level _L2 (time _T1 ), the control device 7 controls the amount of discharge by the pump 6 so that the liquid level of the foam layer B remains constant (liquid level _L2 ) as shown in Fig. 3 from time _T1 to time _T2 . Through this control, the bubbles formed near the interface between the viscous liquid A and the foam layer B and the bubbles that have burst at the top of the foam layer B are in equilibrium, and the foam layer B as a whole is maintained at the liquid level _L2 while the gas in the viscous liquid A is released into the tank 3 through the foam layer B. The gas released into the tank 3 is exhausted to the outside of the tank 3 by the pump 6.

In order to keep the liquid level _L1 of the foam layer B constant (liquid level _L2 ) from time _T1 to time _T2 , the control device 7 may detect the liquid level value of the foam layer B with the liquid level gauge 5 and control the pump 6 so that the liquid level value is kept constant. Alternatively, the output of the pump 6 from time _T1 to time _T2 may be determined (not necessarily constant, but may vary) and the pump 6 may be operated at the determined output depending on the elapsed time from the start of degassing. Such an output of the pump 6 may be obtained by conducting a test in advance. In addition to controlling the pump 6, a suction valve may be provided between the tank 3 and the pump 6, and the pressure in the tank 3 may be adjusted by controlling the opening of the suction valve to keep the liquid level of the foam layer B constant.

As shown from time _T2 to time _T3 in Fig. 3, when the amount of gas contained in the viscous liquid A decreases, the liquid level _L1 of the foam layer B becomes lower than the liquid level _L2 , even though the pump 6 is operating. Then, as shown after time _T3 , when the gas contained in the viscous liquid A is almost gone, the foam layer B returns to the original reference liquid level _L0 . In other words, if the foam layer B shrinks and disappears even though the pump 6 is operating, the gas in the viscous liquid has been sufficiently degassed. Note that the amount of exhaust does not increase much during this period.

When the foam layer B has shrunk to the reference liquid level _L0 in this way, exhaust by the pump 6 is stopped. The foam layer B having shrunk to the reference liquid level _L0 means that the foam layer B has almost disappeared and fallen below the reference liquid level _L0 . The foam layer B having shrunk to the reference liquid level _L0 is determined when the liquid level measured by the level gauge 5 falls below the reference liquid level _L0 . Alternatively, the pump 6 may be stopped based on the elapsed time required for the liquid level to fall below the reference liquid level _L0 . Specifically, the control device 7 stops the pump 6 when the time _T3 has elapsed since the start of degassing (time _T0 ). Such time _T3 can be obtained by conducting a test in advance.

The control device 7 operates the agitator 4 after starting degassing, and agitates the viscous liquid A. There are no particular limitations on the timing of operating the agitator 4, or the agitation speed or time. The agitator 4 agitates the viscous liquid A, and can generate vertical convection. Because the viscous liquid A has a high viscosity, the gas contained in the viscous liquid A does not easily move to the liquid surface. However, the agitation forcibly moves the gas in the viscous liquid A near the liquid surface, forming a foamy layer B, so that the viscous liquid A can be degassed more reliably.

As described above, the degassing system 1 of this embodiment forms a foamy layer B by placing the viscous liquid under negative pressure, and controls the exhaust volume of the pump 6 to keep the foamy layer B constant. In order to maintain the foamy layer B, the pump 6 continues to exhaust the liquid and is not stopped. As exhaust and stopping are not repeated in this way, the time required for degassing can be shortened, and less energy is required than if the pump 6 was started and stopped.

The pressure inside the tank 3 can be increased or decreased by operating and stopping the pump 6 and adjusting its output, causing the foam layer B to repeatedly form and disappear. In this case, it has been empirically and experimentally proven that it takes a long time to degas the viscous liquid. Compared to such cases, the present invention can degas more quickly by maintaining the foam layer B constant.

Furthermore, if the viscous liquid A were degassed directly by applying negative pressure without forming a foam layer B, the liquid level would only fluctuate slightly, making it difficult to determine whether the bubbles had been sufficiently degassed.

However, in the present invention, degassing is performed with a foam layer B formed in the viscous liquid A, and the degassing process is terminated when the foam layer B disappears. The disappearance of the foam layer B is synonymous with the gas being sufficiently degassed from the viscous liquid A, so the risk of gas remaining in the viscous liquid A can be reduced. In addition, whether or not the relatively large foam layer B has disappeared is obvious by visual inspection, and the change from the liquid level _L2 to the reference liquid level _L0 or lower can be detected without error by the liquid level gauge 5. Therefore, the disappearance of the foam layer B can be detected more reliably by visual inspection or the liquid level gauge 5.

Second Embodiment
4 is a schematic diagram showing a tank in the degassing system according to embodiment 2. The tank 10 includes a first tank portion 11 and a second tank portion 12.

The first tank section 11 is a part of the upper side of the tank 10, and the second tank section 12 is a part of the lower side of the tank 10. In other words, the second tank section 12 is provided below the first tank section 11, and these are integrated to form a single tank 10.

The first tank section 11 is formed so that the upper side is cylindrical and the diameter of the lower side (the second tank section 12 side) gradually decreases. The upper part of the first tank section 11 is called the cylindrical section 13, and the lower part is called the tapered section 14.

The cylindrical portion 13 is formed in a generally cylindrical shape and has a lid on the top. Although not shown, the lid on the top is provided with an opening that communicates with the inside of the tank 10, an opening/closing means such as a lid or valve for opening and closing the opening, and a group of devices such as a mechanism for opening and closing the opening/closing means.

The tapered portion 14 is tapered so that its diameter decreases linearly from the top to the bottom. The top of the tapered portion 14 is connected to the cylindrical portion 13, and the bottom is connected to the second tank portion 12.

The second tank section 12 is formed in a substantially cylindrical shape, and the diameter of the second tank section 12 is smaller than the diameter of the first tank section 11 (cylindrical section 13). The second tank section 12 being formed in a cylindrical shape may include not only a cylindrically formed portion, but also a bottom section with a gradually tapered diameter. In the example shown in the figure, the second tank section 12 is composed of a cylindrical upper section and a tapered bottom section with a gradually tapered diameter from the top to the bottom.

The bottom of the second tank section 12 is provided with an extraction section (not shown) for extracting the liquid product obtained by blending the ingredients stored in the tank 10. The extraction section is made up of an opening that communicates with the inside of the tank 10, an opening/closing means such as a lid or valve for opening and closing the opening, and a group of devices such as a mechanism for opening and closing the opening/closing means.

Figure 5 is a schematic diagram showing the tank in use in the degassing system according to embodiment 2. In the example shown in the figure, the volume of the second tank section 12 is 30 L. The volume of the second tank section 12 and the tapered section 14 is 70 L. The volume of the tank 10 (the volume of the second tank section 12, the tapered section 14, and the cylindrical section 13) is 600 L.

When preparing 30 L of a liquid product, various ingredients in the amounts required to prepare the liquid product are placed in the tank 10, and the agitator 4 is operated. As a result, the agitator 4 agitates the ingredients in the second tank section 12, and 30 L of the liquid product is prepared.

When preparing 70 L of a liquid product, various ingredients are added to the tank 10 in the amounts necessary to prepare the liquid product, and the agitator 4 is operated. This causes the agitator 4 to agitate the ingredients in the tapered section 14 and the second tank section 12, and 70 L of a liquid product is prepared.

When preparing 600 L of a liquid product, various ingredients are added to the tank 10 in the amounts required to prepare the liquid product, and the agitator 4 is operated. This causes the agitator 4 to agitate the ingredients in the tank 10, and 600 L of the liquid product is prepared.

The tank 10 configured as described above can prepare a small volume of liquid product in the second tank section 12, and prepare a large volume of liquid product in the first tank section 11 and the second tank section 12. In other words, a single tank 10 can prepare various volumes of liquid product, from small to large. Of course, the volume of the liquid product to be prepared is not limited to 30L, 70L, or 600L.

Here, a case will be described in which a quantity of viscous liquid that does not exceed the second tank portion 12 is stored in the second tank portion 12, and the gas in this viscous liquid is degassed. As in the first embodiment, a pump 6 (not shown) is operated to form a foamy layer B. The liquid level of this foamy layer B is made to exceed the second tank portion 12. By exceeding the second tank portion 12, a foamy layer B is formed from the second tank portion 12 to the first tank portion 11, which has a larger diameter.

The foam layer B thus formed has an area equivalent to that of the first tank portion 11 when viewed in a plan view. In other words, it is larger than the area of the second tank portion 12 when viewed in a plan view. In this way, the foam layer B comes into contact with the space inside the tank 10 over a larger area compared to when the foam layer B is contained within the second tank portion 12 (not shown), so that more air bubbles can be released quickly into the space inside the tank 10.

In this way, the degassing system 1 of this embodiment can process both large and small volumes of viscous liquid in a single tank 10, and can degas small volumes of viscous liquid more quickly.

Third Embodiment
6 is a schematic diagram showing a degassing system according to embodiment 3. The degassing system 1 of this embodiment includes a tank 20, a filter device 21, an injection unit 22, a first pump 23, and a second pump 24.

The tank 20 has an outlet at the bottom, and a first pipe 30 is provided to connect the outlet to the filter device 21.

The filter device 21 has a primary side connected to the tank 20 via a first pipe 30, and a secondary side connected to the injection unit 22 via a second pipe 31. The filter device 21 captures gas contained in the viscous liquid A supplied from the tank 20. The filter device 21 may be of a dead-end type or a cross-flow type.

The ejection unit 22 is a device that ejects the viscous liquid sent from the second pipe 31 toward the inside of the tank 20. Specifically, the ejection unit 22 can be of the well-known shower ball type, roller ball type, push-out ball type, jet washer type, diffusion nozzle type, 2D nozzle in which the nozzle itself rotates due to the reaction force of the ejected liquid, 3D nozzle in which the nozzle itself rotates and revolves due to the reaction force of the ejected liquid, etc.

The second pipe 31 is connected to the tank 20 via a third pipe 32 that branches off midway. A portion of the viscous liquid is supplied to the inner surface of the tank 20 via the third pipe 32. A first pump 23 for pumping the viscous liquid is provided midway along the first pipe 30, and a second pump 24 for removing bubbles captured by the filter is connected to the primary side of the filter device 21.

Although not specifically shown, the degassing system 1 is also provided with a pump that exhausts gas from the tank 20, similar to that of embodiment 1.

The degassing system 1 of this embodiment is capable of degassing by forming a foam layer B by exhausting air using a pump, as in the first embodiment. The control device 7 (see FIG. 1) operates the first pump 23 to supply viscous liquid from the tank 20 to the filter device 21, causing the filter device 21 to remove gas (bubbles), and then causes the viscous liquid that has passed through the filter device 21 to be sprayed from the spray unit 22 into the inside of the tank 20. The viscous liquid sprayed from the spray unit 22 into the inside of the tank 20 falls on the foam layer B, promoting the destruction of the bubbles. This allows the gas in the foam layer B to be released more quickly into the internal space of the tank 20, shortening the time required for degassing.

Other Embodiments
Although each embodiment of the present invention has been described above, the basic configuration of the present invention is not limited to the above.

For example, in each embodiment, the raw material supply means 2 is provided, but is not a required component, and the raw material may be manually supplied to the tank 3. The stirring device 4 is also not a required component. The degassing is started after the raw material is charged, but is not limited to this timing. For example, degassing may be started while the raw material is being charged. In embodiment 2, a two-tier tank 10 is illustrated, but the present invention is not limited to two tiers, and can also be applied to a tank with three or more tiers.

1... Degassing system, 2... Raw material supply means, 3, 10, 20... Tank, 4... Mixing device, 5... Level gauge, 6... Pump, 7... Control device

Claims (4)

A degassing system for degassing a viscous liquid having dissolved gas, comprising:
A tank for storing the viscous liquid;
A pump for discharging gas from inside the tank;
A control device for controlling the pump,
The control device includes:
The liquid level inside the tank when the pump is stopped is set as a reference liquid level,
Operate the pump to evacuate the gas from the tank to form a foam layer on top of the viscous liquid;
Controlling the amount of discharge by the pump so that the liquid level of the foam layer is constant;
A degassing system, characterized in that when the foam layer shrinks to the reference liquid level even though the pump is exhausting the gas from the tank, exhaust by the pump is stopped. 2. The degassing system of claim 1,
The tank includes a first tank portion and a second tank portion provided below the first tank portion and having a smaller diameter than the first tank portion,
The viscous liquid is stored in an amount not exceeding the second tank portion,
The control device is configured to operate the pump to exhaust gas from the tank, thereby forming the foam layer so as to exceed the second tank portion. 2. The degassing system of claim 1,
an ejection unit that ejects the viscous liquid into the tank;
a filter device having a primary side connected to the tank and a secondary side connected to the ejection unit, the filter device removing air bubbles contained in the viscous liquid sent from the tank to the ejection unit;
The control device causes the viscous liquid to be sprayed from the tank through the filter device and from the spray unit while operating the pump to form the foam layer. The degassing system according to any one of claims 1 to 3,
a stirring device that stirs the viscous liquid stored in the tank,
The degassing system according to claim 1, wherein the control device causes the agitator to agitate the inside of the tank while exhausting the air with the pump.

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