Tank equipment and liquid supply system

Abstract

To provide tank equipment and a liquid supply system that can suppress hunting in a short time with simpler control and supply liquid stored in a tank at a constant pressure.SOLUTION: Tank equipment comprises a tank 20 for storing a chemical liquid, a second line 6 for supplying the liquid to a downstream filling machine 3 from the tank 20, air supply means 30 for supplying gas to the tank 20, and exhaust means 40 for discharging the gas from the tank 20. The air supply means 30 supplies the gas at a constant pressure to a space S above the liquid level of the chemical liquid stored in the tank 20, and the exhaust means 40 discharges the gas from the space S to offset fluctuations in the pressure of the liquid stored in the tank 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tank device and a liquid delivery system that delivers liquid stored in a tank at a constant pressure. [Background technology]

[0002] Conventionally, a liquid product is stored in a tank and the liquid is supplied to a downstream device such as a filling machine at a constant pressure. For example, Patent Document 1 discloses a device equipped with an air supply system that supplies gas to the inside of the tank and an exhaust system that exhausts the gas from the inside. The air supply system and the exhaust system are each equipped with a control valve, and the control valve is controlled so that the pressure inside the tank becomes a target pressure. This pressure control makes it possible to supply the liquid downstream at a constant pressure.

[0003] When liquid is supplied to the tank, the pressure inside the tank increases. The air supply system controls the control valve to lower the pressure inside the tank when the pressure increases. This reduces the pressure inside the tank, but it rarely reaches the target pressure in one go, and it may fall below the target pressure. Therefore, the air supply system controls the control valve to increase the pressure inside the tank. In this case, the pressure inside the tank may not reach the target pressure but may exceed it. In this way, the pressure inside the tank fluctuates above and below the target pressure, resulting in so-called hunting. This type of hunting can also occur when liquid is discharged from the tank and the pressure inside the tank decreases. Hunting will eventually converge by repeating this control, but it is desirable to suppress it in a short period of time.

[0004] Furthermore, if pressure control is performed not only on the intake system but also on the exhaust system, the intake system and the exhaust system must be linked, which makes the control to suppress hunting even more complicated and may prolong the hunting period. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-315045 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, the present invention aims to provide a tank device and a liquid delivery system that can reduce hunting to a short period of time with simpler control and deliver liquid stored in a tank at a constant pressure. [Means for solving the problem]

[0007] One aspect of the present invention for achieving the above-mentioned object is a tank device comprising a tank for storing liquid, a supply line for supplying liquid from the tank to a downstream processing device, an air supply means for supplying gas to the tank, and an exhaust means for discharging gas from the tank, wherein the air supply means supplies gas at a constant pressure to a space above the liquid level of the liquid stored in the tank, and the exhaust means discharges gas from the space so as to counteract fluctuations in the pressure of the liquid stored in the tank.

[0008] One aspect of the present invention for achieving the above object is a liquid delivery system comprising the tank device described in the above aspect and a processing device that operates on the premise that liquid is supplied from the tank at a constant pressure. [Effects of the Invention]

[0009] According to the present invention, a tank device and a liquid delivery system are provided that can suppress hunting to a short time with simpler control and deliver liquid stored in a tank at a constant pressure. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating a liquid transfer system including a tank device. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1 is a schematic diagram of a liquid delivery system including a tank device according to this embodiment. The liquid delivery system 1 of this embodiment includes a compounding tank 2, a tank device 10, and a filling machine 3. The liquid delivery system 1 of this embodiment is part of a plant that produces a liquid medicine (hereinafter, referred to as a liquid medicine) as an example of a liquid.

[0012] The blending tank 2 is a tank that receives and blends raw materials for chemical solutions, solvents such as water, and the like. The blending tank 2 and tank 20 are connected by a first line 4, and the chemical solution is supplied from the blending tank 2 to the tank 20. A first on-off valve 5 is provided on the first line 4, which allows switching between starting and stopping the delivery of the chemical solution. The blending tank 2 is an example of an upstream tank that supplies liquid to the tank 20.

[0013] The filling machine 3 is a device that receives the liquid medicine from the tank 20 and fills it into a container (not shown). The filling machine 3 and the tank 20 are connected by a second line 6 (supply line), and the liquid medicine is supplied from the tank 20 to the filling machine 3. A second on-off valve 7 is provided on the second line 6, which allows switching between starting and stopping the supply of the liquid medicine. The filling machine 3 performs the filling process on the premise that the liquid medicine is supplied from the tank 20 at a constant pressure. In the liquid supply system 1, the pressure of the liquid medicine supplied to the filling machine 3 (hereinafter referred to as the inlet pressure) is set so that the liquid medicine is accurately filled into the container. A pressure gauge 8 for measuring this inlet pressure is provided on the second line 6.

[0014] The tank device 10 includes a tank 20, an air supply means 30, and an exhaust means 40.

[0015] Tank 20 is a tank that stores the chemical liquid supplied from blending tank 2. Tank 20 is a general tank, and although not shown, may be equipped with a jacket for maintaining the temperature of the chemical liquid and sensors for measuring the temperature and liquid level of the chemical liquid. Tank 20 has a space S above the liquid level of the chemical liquid, and the pressure of the chemical liquid is adjusted by adjusting the pressure of the gas in space S.

[0016] The gas supply means 30 is a group of devices that supply gas to the space S of the tank 20. Specifically, the gas supply means 30 includes a gas supply line 31, a first filter device 32, and a gas supply device 33. The gas supply line 31 is a pipeline that connects the gas supply device 33 to the tank 20. The first filter device 32 is a device that removes foreign matter from the gas flowing through the gas supply line 31. The gas supply device 33 is not particularly limited as long as it is a device that supplies gas at a constant pressure, but for example, it is composed of a gas supply source such as a pump that compresses air and a tank that holds compressed air, and a pressure reducing valve that reduces the air to a constant pressure.

[0017] The gas supplied from the gas supply device 33 passes through the gas supply line 31, and foreign matter is removed by the first filter device 32 before being supplied to the tank 20. The pressure of the gas supplied by the gas supply device 33 is set to be equal to or higher than the target pressure to be applied to the chemical solution stored in the tank 20. Note that, although the gas supply means 30 includes the first filter device 32 in this embodiment, it is not essential as long as the above-mentioned supply source supplies clean air.

[0018] The exhaust means 40 is a group of devices that exhaust gas from the space S of the tank 20. Specifically, the exhaust means 40 includes an exhaust line 41, a second filter device 42, a control valve 43, and a check valve 44. The exhaust line 41 is a connecting pipe that exhausts the space S of the tank 20 to the outside. The second filter device 42 is a device that removes foreign matter contained in the outside air (outside air) and prevents foreign matter from mixing into the space S from the outside air. The control valve 43 exhausts gas from the space S of the tank 20 so as to cancel out pressure fluctuations in the space S. The exhaust operation by the exhaust means 40 will be described later. The check valve 44 is a valve that exhausts gas in one direction from the exhaust line 41 to the outside.

[0019] The liquid delivery system 1 also includes a control device (not shown). The control device controls the operation of the liquid delivery system 1, and one of the operations is to control the pressure of the liquid medicine supplied from the tank 20 to the filling machine 3. This pressure control is performed as follows.

[0020] The gas is supplied by the gas supply means 30 so that the pressure of the gas supplied to the space S is constant. This pressure control may be achieved by manually adjusting a pressure reducing valve, or a control valve may be provided instead of a pressure reducing valve, and the control valve may be controlled by a control device to control the pressure of the gas supplied by the gas supply means 30. The pressure of the gas supplied by the gas supply means 30 is set to be equal to or higher than the target pressure to be applied to the chemical solution stored in the tank 20, as described above.

[0021] The exhaust of gas by the exhaust means 40 discharges gas from the tank 20 so as to cancel out pressure fluctuations in the space S. Specifically, the control device reads the pressure (hereinafter referred to as the measured pressure) using the pressure gauge 8 and adjusts the aperture of the control valve 43 so that this measured pressure becomes the target pressure. If the measured pressure exceeds the target pressure, the control device increases the aperture of the control valve 43. On the other hand, if the measured pressure is below the target pressure, the control device decreases the aperture of the control valve 43. Such control can be achieved by a known control method, for example, PID control.

[0022] Pressure fluctuations in the liquid medicine may occur when the liquid medicine is sent from the blending tank 2 to the tank 20 or when the liquid medicine is discharged from the tank 20. However, as described above, by controlling the supply and exhaust of gas by the gas supply means 30 and the exhaust means 40, the pressure fluctuations in the liquid medicine in the tank 20 are canceled out, and the liquid medicine can be sent from the tank 20 to the filling machine 3 at a constant pressure.

[0023] Furthermore, in controlling the supply and exhaust of the space S, the pressure of the gas supplied by the air supply means 30 remains constant, while only the pressure of the gas exhausted by the exhaust means 40 fluctuates. By separating the supply and exhaust paths and controlling only the exhaust pressure, hunting is less likely to occur, and even if it does occur, it can be resolved quickly. In other words, the air supply means 30 does not fluctuate the supply pressure to reach the target pressure, so hunting is less likely to occur. Furthermore, if pressure control were performed by both the air supply means 30 and the exhaust means 40, the influence of pressure control by one would affect the other, complicating control and making it difficult to suppress hunting. This invention is particularly useful when the pressure range of the gas regulated by the exhaust means 40 is set to a very small pressure. A very small pressure is between 0.5% and 5% of the pressure of the gas supplied by the air supply means 30. Attempting to control pressure in both the air supply system and the exhaust system, as in the prior art, requires coordination between the air supply system and the exhaust system, resulting in extremely difficult control. Furthermore, if pressure is controlled solely by the air supply system, the higher the target pressure, the more difficult it is to adjust it within a very small pressure range, and it is possible that the pressure may fluctuate by more than ±10% from the target pressure. However, in the present invention, the air supply means 30 supplies air at a constant pressure, and the exhaust means 40 controls the exhaust within a very small pressure range. This makes it possible to limit the fluctuation range of the liquid pressure to within a very small pressure range from the target pressure, even if the target pressure is high.

[0024] As described above, the liquid delivery system 1 and tank device 10 of this embodiment can deliver the liquid from the tank device 10 to the filling machine 3 while maintaining a constant pressure of the delivered liquid medicine. Furthermore, for liquid medicine pressure control, the pressure of the air supplied by the air supply means 30 is kept constant, and the pressure of the exhaust by the exhaust means 40 is controlled (the opening of the control valve 43). This prevents hunting of the pressure of the liquid medicine stored in the tank 20, and even if hunting does occur, it can be resolved in a short time.

[0025] Furthermore, the liquid delivery system 1 and the tank device 10 set the inlet pressure immediately before the filling machine 3 as the target pressure. In other words, the target pressure is the pressure of the liquid medicine in the second line 6, not the pressure of the gas in the space S of the tank 20 or the pressure of the liquid medicine stored in the tank 20. This makes it possible to more reliably deliver the liquid medicine at the target pressure to the filling machine 3. Although the pressure of the liquid medicine can vary depending on the shape, route, and devices such as valves installed along the way of the second line 6, if the inlet pressure immediately before the filling machine 3 is set as the target pressure, the influence of such shape and other factors on the pressure can be ignored.

[0026] The liquid delivery system 1 of the present invention can employ even a relatively small tank 20. In other words, even if a small tank 20 is employed, hunting can be suppressed in a short time and the liquid medicine can be supplied to the filling machine 3 at a constant pressure. In the present invention, a small tank 20 has a capacity of 0.5 L or more and 50 L or less. Alternatively, the capacity is 0.05% or more and 0.1% or less of the capacity of the blending tank 2 that supplies the liquid medicine to the tank 20. Compared to a large tank, the pressure applied to the liquid medicine in a small tank 20 quickly follows the exhaust control by the exhaust means 40. Therefore, the pressure applied to the liquid medicine in the tank 20 can quickly reach the target pressure. Furthermore, the weight of the liquid stored in the tank 20 fluctuates as the liquid flows in and out of the tank 20, which can affect the downstream inlet pressure. However, if the capacity of the tank 20 is small, the amount of liquid is small and the fluctuation in the weight can be almost negligible. This facilitates control to set the inlet pressure to the target pressure.

[0027] The above describes one embodiment of the present invention. However, the present invention is not limited to the above embodiment, and additions, omissions, substitutions, and other modifications of the configuration are possible within the scope of the spirit of the present invention.

[0028] For example, the device that delivers the liquid to the tank device 10 is not limited to the blending tank 2. Furthermore, the target to which the liquid is delivered from the tank device 10 is not limited to the filling machine 3. Any processing device that can supply the liquid medicine at a constant pressure may be used.

[0029] For example, the exhaust of the exhaust means 40 was controlled so that the inlet pressure of the chemical liquid in the second line 6 would be the target pressure, but this is not limiting. For example, if pressure fluctuations due to the shape of the second line 6 or the like can be ignored, the pressure of the gas in the space S may be set to the target pressure. Furthermore, the liquid is not limited to chemical liquids, and the present invention can be applied to any liquid.

[0030] Furthermore, in this embodiment, the filling machine 3 is exemplified, but the present invention is not limited to this, and can be applied to any processing device that performs processing on the premise that liquid is supplied at a constant pressure. [Explanation of symbols]

[0031] S...space, 1...liquid transfer system, 2...blending tank, 3...filling machine, 10...tank device, 20...tank, 30...air supply means, 40...exhaust means

Claims

1. a tank for storing a liquid; a supply line for supplying liquid from the tank to a downstream processing unit; an air supply means for supplying gas to the tank; and an exhaust means for exhausting gas from the tank, the gas supply means supplies gas at a constant pressure to a space above the liquid level stored in the tank; The exhaust means exhausts gas from the space so as to counteract fluctuations in pressure of the liquid stored in the tank. A tank device characterized by:

2. 2. The tank device according to claim 1, The exhaust means measures the pressure of the liquid flowing through the supply line and controls the amount of gas discharged from the tank based on the pressure. A tank device characterized by:

3. 2. The tank device according to claim 1, the gas supply means includes a pressure reducing valve that adjusts the pressure of the gas to be supplied to the tank to a constant pressure, The exhaust means includes a control valve that measures the pressure of the liquid flowing through the supply line and controls the amount of gas exhausted from the tank based on the pressure. A tank device characterized by:

4. 2. The tank device according to claim 1, The pressure range of the gas adjusted by the exhaust means is 0.5% to 5% of the pressure of the gas supplied by the gas supply means. A tank device characterized by:

5. 2. The tank device according to claim 1, The tank has a capacity of 0.5 L or more and 50 L or less. A tank device characterized by:

6. A tank device according to any one of claims 1 to 5; a treatment device that operates on the premise that liquid is supplied from the tank at a constant pressure; A liquid delivery system comprising:

7. 7. The liquid delivery system according to claim 6, an upstream tank that supplies liquid to the tank; The volume of the tank is 0.05% to 0.1% of the volume of the upstream tank. A liquid delivery system characterized by:

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