Processing system for liquid to be treated

Abstract

The present invention provides a treatment system for a liquid to be treated that can suppress fluctuations in flow rate and inhibit foaming of the liquid being treated. [Solution] The system comprises a tank 10 for storing the liquid to be treated, a filter device 20, a first flow path 31, a second flow path 32, a third flow path 33 for supplying the liquid to be treated from a branch point P in the middle of the second flow path 32 to a confluence point Q in the middle of the first flow path 31, a pump 40 positioned between the confluence point Q and the filter device 20, and a control device 50 for controlling the pump 40 so that the flow rate of the liquid to be treated flowing through the circulation flow path 30, which is composed of the first flow path section 31b, the second flow path section 32a, and the third flow path 33, remains constant.

Description

[Technical Field]

[0001] The present invention relates to a processing system that can continuously filter a liquid to be processed using a filter device. [Background technology]

[0002] As disclosed in Patent Document 1, a processing system is known in which a tank and a filter device are connected by a circulation channel, and the liquid to be processed is filtered while being circulated, and then concentrated or purified. Recently, such processing systems are required to supply the liquid to be processed to the filter device at a high linear velocity in order to shorten the processing time.

[0003] However, as the process progresses and the treated liquid becomes more concentrated, its concentration increases. If the process continues at the same linear velocity as before despite the increased concentration, the pressure at the inlet of the filter device will rise too high. For example, it may exceed the pressure allowed by the filter device. Also, when the treated liquid is returned from the circulation channel to the tank, it will foam up inside the tank. This foaming can become more pronounced at higher linear velocities. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-130072 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In view of these circumstances, the present invention aims to provide a treatment system for a liquid to be treated that can suppress fluctuations in flow rate and inhibit foaming of the liquid to be treated. [Means for solving the problem]

[0006] A first embodiment for achieving the above objective is a liquid treatment system comprising: a tank for storing the liquid to be treated; a filter device; a first flow path for supplying the liquid to be treated from the tank to the filter device; a second flow path for supplying the liquid to be treated from the filter device to the tank; a third flow path for supplying the liquid to be treated from a branch in the middle of the second flow path to a confluence in the middle of the first flow path; a pump disposed between the confluence and the filter device; and a control device for controlling the pump so that the flow rate of the liquid to be treated flowing through the circulation path composed of the first, second, and third flow paths remains constant. [Effects of the Invention]

[0007] According to the present invention, a treatment system for a liquid to be treated is provided that can suppress fluctuations in flow rate and inhibit foaming of the liquid to be treated. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of the treatment system for the liquid to be treated. [Modes for carrying out the invention]

[0009] Figure 1 is a schematic diagram of the treatment system for the liquid to be treated according to this embodiment. In this embodiment, a treatment system that concentrates the liquid to be treated by filtering it will be described. The treatment system 1 includes a tank 10, a filter device 20, a circulation channel 30, a pump 40, various control valves, and a control device 50 that controls the pump 40, control valves, etc.

[0010] The liquid to be treated is not particularly limited, but can be a solution containing various solutes, such as beverages, pharmaceuticals, paints, and microorganisms. The liquid to be treated contains a variety of components. Before the circulation filtration described later, the liquid to be treated may be classified by pretreatment such as centrifugation.

[0011] Tank 10 is a tank that stores the liquid to be treated supplied from a liquid to be treated source (not shown) and also stores the liquid to be treated that has been circulated from the filter device 20. The supply source is, for example, a device that prepares the liquid to be treated from raw materials and solvents, or a device such as a centrifuge.

[0012] The filter device 20 is equipped with a filter 21. The upstream side to which the liquid to be processed is supplied to the filter 21 is referred to as the primary side A, and the opposite side is referred to as the secondary side B. Although the processing system 1 is illustrated with one filter device 20, there is no limit to the number of devices.

[0013] The filtration device 20 is a device that filters the liquid to be processed using a cross-flow method with a filter 21. The filter 21 is appropriately selected according to the desired purpose. Examples of filters 21 include ceramic NF membranes with fractionation performance of several hundred daltons to one thousand daltons, ceramic MF membranes from 10 nm to 2 μm, ceramic UF membranes from 1 k Dalton to 300 k Dalton and 5 nm, organic NF membranes of several hundred daltons, organic UF membranes of 1 k Dalton or more, and organic MF membranes of 0.1 μm or more. Note that NF membranes are nanofilter membranes, MF membranes are precision filter membranes, and UF membranes are ultrafiltration membranes.

[0014] Furthermore, a permeate pipe 22 is connected to the secondary side B of the filter device 20. The permeate pipe 22 is the pipe through which the liquid to be treated, filtered by the filter 21 of the filter device 20, flows as permeate.

[0015] The tank 10 and the filter device 20 are connected by piping so that the liquid to be treated circulates. Specifically, the processing system 1 is equipped with a first flow path 31, a second flow path 32, and a third flow path 33.

[0016] The first flow path 31 is a flow path constituted by a pipe for feeding the liquid to be treated from the tank 10 to the filter device 20. The second flow path 32 is a flow path constituted by a pipe for feeding the liquid to be treated from the filter device 20 to the tank 10. The third flow path 33 is a flow path constituted by a pipe for feeding the liquid to be treated from the branch portion P in the middle of the second flow path 32 to the confluence portion Q in the middle of the first flow path 31.

[0017] The portion of the first flow path 31 from the tank 10 to the confluence portion Q is also referred to as the first flow path portion 31a, and the portion of the first flow path 31 from the confluence portion Q to the filter device 20 is also referred to as the first flow path portion 31b.

[0018] The portion of the second flow path 32 from the filter device 20 to the branch portion P is also referred to as the second flow path portion 32a, and the portion of the second flow path 32 from the branch portion P to the tank 10 is also referred to as the second flow path portion 32b.

[0019] The first flow path portion 31b, the second flow path portion 32a, and the third flow path 33 are collectively referred to as the circulation flow path 30.

[0020] Between the confluence portion Q and the filter device 20, that is, in the first flow path portion 31b, a pump 40, a first flow meter 41, and a pressure gauge 42 are provided. The first flow meter 41 and the pressure gauge 42 are downstream of the pump 40 and upstream of the filter device 20. The first flow meter 41 is arranged upstream (on the pump 40 side) of the pressure gauge 42, but the reverse arrangement is also possible. The pump 40 is a device for pressure-feeding the liquid to be treated to the filter device 20, and there is no particular limitation on the type. The first flow meter 41 is a device for measuring the flow rate of the liquid to be treated upstream of the filter device 20, and the flow rate can be referred to by the control device 50. The pressure gauge 42 is a device for measuring the pressure of the liquid to be treated upstream of the filter device 20, and the pressure can be referred to by the control device 50. The pressure measured by the pressure gauge 42 is the pressure at the inlet of the filter device 20, and hereinafter, it is also referred to as the inlet pressure. The output of the pump 40 is controlled by the control device 50 so that the flow rate of the liquid to be treated becomes a predetermined amount based on the flow rate of the first flow meter 41 and the pressure of the pressure gauge 42.

[0021] Furthermore, a fourth flow path 34 is provided between the pump 40 and the filter device 20, branching off from the first flow path section 31b. A switching valve 35 is provided between the first flow path section 31b and the fourth flow path 34.

[0022] A secondary control valve 23 is provided in the permeate piping 22, extending downstream from the filter device 20. The secondary control valve 23 is a control valve for controlling the pressure of the liquid being treated in the permeate piping 22 (i.e., the pressure of the liquid being treated on the secondary side B).

[0023] Between the branching section P and the tank 10, i.e., in the second flow path section 32b, a return volume control valve 60 is provided on the tank 10 side, and a second flow meter 61 is provided on the branching section P side. The return volume control valve 60 is a valve device provided in the second flow path section 32b, and its opening degree is controlled by the control device 50. By controlling this opening degree, the ratio of the flow rate from the branching section P to the merging section Q and the flow rate from the branching section P to the tank 10 can be changed. The second flow meter 61 is a device that measures the flow rate through the second flow path section 32b, and its flow rate can be referenced by the control device 50.

[0024] In the processing system 1 configured as described above, the liquid to be processed is sent from the tank 10 and the third flow path 33 to the pump 40, and then pumped to the filter device 20 by the pump 40. The liquid is sent from the tank 10 to the pump 40 by the weight of the liquid stored in the tank 10, but the system is not limited to this method of liquid transfer. For example, air may be supplied to the tank 10, and the liquid may be sent from the tank 10 to the pump 40 by the pressure of the air.

[0025] In the filter device 20, the liquid to be treated filtered by filter 21 is sent as permeate to the permeate piping 22 from the secondary side B. On the other hand, the liquid to be treated that was not filtered by the filter device 20 is discharged into the second flow path 32.

[0026] The liquid to be treated, discharged into the second channel 32, branches off at the branching point P. A portion of the liquid to be treated returns to the first channel 31 through the third channel 33, and the remainder returns to the tank 10.

[0027] In this manner, the liquid to be treated is filtered by the filter device 20, and then a portion of it is circulated through the circulation channel 30, while the remainder is returned to the tank 10, thus performing a circulating filtration process. During this circulating filtration, the switching valve 35 is closed, preventing the liquid to be treated from flowing into the fourth channel 34.

[0028] Such circulating filtration is controlled by a control device 50. The control device 50 is also called a programmable controller or sequencer. The control device 50 is equipped with a CPU and memory, and reads and executes control programs stored in the memory. Note that the control device 50 is not limited to one unit, but may be operated by multiple units as described later.

[0029] The control by the control device 50 will now be described in detail. The control device 50 controls the pump 40 by executing a control program so that the linear velocity of the liquid to be treated at the inlet of the filter device 20 becomes high linear velocity. Linear velocity is defined as the flow rate of the liquid to be treated divided by the cross-sectional area through which the liquid to be treated flows in the filter device 20. High linear velocity is set appropriately according to the properties of the liquid to be treated and the configuration of the filter 21, but it is preferably between 3 and 10 [m / sec].

[0030] Table 1 shows the current values ​​and set values ​​for each pressure gauge and flow meter. [Table 1]

[0031] Floop(PV) is the current value of the flow rate of the liquid being treated in the first flow channel section 31b (hereinafter referred to as the circulating flow rate). Specifically, Floop(PV) is the current value of the circulating flow rate measured by the first flow meter 41. Floop(SV) is the set value for the circulating flow rate.

[0032] Fret(PV) is the current value of the flow rate returning to the tank 10 among the circulation flow rate (hereinafter referred to as the return flow rate). Specifically, Fret(PV) is the current value of the flow rate measured by the second flow meter 61. Fret(SV) is the set value for the flow rate. Floop(SV) and Fret(SV) are initially set in the control device 50 in advance.

[0033] Pin(PV) is the current value of the inlet pressure. Specifically, Pin(PV) is the current value of the inlet pressure measured by the pressure gauge 42. Pin(SV) is the set value for the inlet pressure. As an example of Pin(SV), the upper limit pressure allowed for the filter device 20 is set.

[0034] The flow rate measured by the first flow meter 41 (set flow rate Floop(SV)) is set to 200 [m 3 / h]. The liquid to be treated is filtered by the filter device 20, and the amount passing through the filter 21 (hereinafter referred to as the permeate amount) is 2 [m 3 / h]. The flow rate of the liquid to be treated discharged from the filter device 20 is 198 [m 3 / h]. A part of this flows from the branch part P to the confluence part Q, and the flow rate is 192 [m 3 / h], and the remainder flows from the branch part P to the tank 10, and the flow rate is 6 [m 3 / h]. The flow rate of the liquid to be treated supplied from the tank 10 to the confluence part Q is 8 [m 3 / h]. 200 [m 3 / h] of the liquid to be treated flows into the pump 40 from the confluence part Q.

[0035] The filter device 20 is supplied with the liquid to be treated at a flow rate of 200 m [m 3 / h], and discharges 2 [m 3 / h] as the permeate amount from the circulation channel 30, and the liquid to be treated is concentrated. By the filter device 20, the liquid to be treated decreases by the amount of the permeation flow rate, but the liquid to be treated supplied from the tank 10 is added, so that a substantially constant amount of the liquid to be treated is supplied to the inlet side of the pump 40. In this way, in the circulation channel 30, 200 [m 3It is possible to supply the liquid to be processed at [ / h] to the filter device 20.

[0036] The control device 50 uses PID control to adjust the output of the pump 40 to achieve the initially set Floop (SV). PID control ensures that a constant flow rate of the liquid to be treated is supplied from the pump 40 to the filter device 20. However, as described in the background information, if the processing continues at the same linear velocity as the initial stage, even though the concentration increases as the process progresses, the pressure at the inlet of the filter device will rise too high.

[0037] Therefore, when the control device 50 detects that the current inlet pressure, Pin(PV), exceeds the set upper pressure limit, Pin(SV), it lowers the set value Floop(SV). The control device 50 then uses PID control to adjust the output of the pump 40 so that the current value Floop(PV) becomes the updated set value Floop(SV). In other words, it lowers the output of the pump 40. This ensures that even as concentration progresses in the filter device 20, the inlet pressure of the filter device 20 does not exceed the upper limit, and the flow rate of the liquid to be treated flowing through the circulation channel 30 remains stable. There are no particular limitations on the extent to which the set value Floop(SV) is lowered. For example, the new set value Floop(SV) may be set by lowering the initial set value Floop(SV) by a predetermined amount or percentage.

[0038] This control of the pump 40 maintains the circulation flow rate of the liquid to be treated at the set value Floop(SV). The control device 50 also uses PID control to adjust the opening of the return volume control valve 60 so that the current value Fret(PV) of the flow rate from the branching section P to the tank 10 becomes the set value Fret(SV). With this control, a portion of the liquid to be treated returns to the confluence section Q, and the remainder returns to the tank 10, maintaining a constant ratio of this portion to the remainder.

[0039] In this way, the flow rate of the liquid to be treated flowing through the circulation channel 30 can be stabilized, allowing the liquid to be treated to be supplied to the filter device 20 at a constant high linear velocity. In addition, although a portion of the liquid to be treated is returned to the tank 10, its flow rate is far less than that in the circulation channel 30. In the example in Figure 1, the flow rate returning to the tank 10 is 6 [m³]. 3 The flow rate is 200 (198 in the second flow channel 32a and 192 in the third flow channel 33), and the flow rate through the circulation channel 30 is 200. In this way, only a small amount of the liquid to be treated returns to the tank 10, so the generation of foam when the liquid to be treated is released into the tank 10 can be suppressed. Furthermore, as described above, the flow rate of the liquid to be treated flowing through the circulation channel 30 is controlled and stabilized to be Floop(SV), so the flow rate of the liquid to be treated returning to the tank 10 is also stable with little fluctuation. Because the flow rate fluctuates little in this way, foaming caused by the liquid to be treated returning to the tank 10 can be suppressed even more effectively.

[0040] The liquid to be treated is concentrated by circulating filtration, and when the liquid reaches a predetermined concentration, the circulating filtration is stopped. After that, the following process may be performed. The return volume control valve 60 is closed, and the liquid to be treated is not returned to the tank 10, while the liquid to be treated is circulated and filtered in the circulating channel 30. At this time, an amount of liquid to be treated corresponding to the amount of permeate that has passed through the filter device 20 is supplied from the tank 10 to the circulating channel 30. As a result, the concentration of the liquid to be treated in the treatment system 1 increases further, and it can be concentrated to the limit of the concentration that can be pumped by the pump 40. Such a process cannot be performed if a pump is installed in the first channel section 31a.

[0041] The determination of whether the liquid to be treated has reached a predetermined concentration can be made, for example, by considering it to have reached a predetermined concentration when the amount of liquid to be treated stored in tank 10 decreases to a predetermined amount. Alternatively, the liquid to be treated can be sampled from the first to third flow channels 31 to 33, its concentration measured, and its concentration determined. After the liquid to be treated reaches the predetermined concentration through circulation filtration, the control device 50 opens the switching valve 35. Then, by operating the pump 40, the liquid to be treated in the first to third flow channels 31 to 33 is sent to the fourth flow channel 34. The fourth flow channel 34 is connected to various devices that process the liquid to be treated, such as an aseptic tank or a filling machine. In this way, the liquid to be treated, now at the predetermined concentration, is sent to the various devices for the next process.

[0042] As described above, the treatment system 1 for the liquid to be treated sends the liquid to be treated from the tank 10 to the filter device 20 for filtration, and returns a portion of the liquid discharged from the filter device 20 to the pump 40 and the remainder to the tank 10. The liquid to be treated is filtered while circulating through the circulation channel 30, and a portion of it returns to the tank 10. When performing this circulating filtration, the pump 40 is controlled so that the flow rate of the liquid to be treated supplied to the filter device 20 remains constant.

[0043] By controlling the pump 40 in this way, the flow rate of the liquid to be treated supplied to the filter device 20 in the circulation channel 30 can be stabilized, and the flow rate of the liquid to be treated returning to the tank 10 can also be stabilized with minimal fluctuations. As a result, foaming can be suppressed even when the liquid to be treated is returned from the circulation channel 30 to the tank 10 where it is temporarily stored.

[0044] Furthermore, the treatment system 1 for the liquid to be treated is equipped with a first flow meter 41 and a pressure gauge 42 upstream of the filter device 20. The control device 50 controls the pump 40 so that the flow rate of the liquid to be treated, as measured by the first flow meter 41, reaches a predetermined value (Floop(SV)). When the current value Pin(PV) of the inlet pressure measured by the pressure gauge 42 exceeds the set value Pin(SV), the control device 50 reduces the set value Floop(SV) of the circulating flow rate by a certain amount. With this control, even if the concentration of the liquid to be treated increases as concentration progresses in the circulating channel 30, the flow rate of the liquid to be treated flowing through the circulating channel 30 can be stabilized without exceeding the set value Pin(SV) of the pressure.

[0045] Furthermore, the liquid treatment system 1 is equipped with a return volume control valve 60 that adjusts the opening degree of the second flow path section 32b so that the ratio of the flow rate from the branch section P to the confluence section Q to the flow rate from the branch section P to the tank 10 is 20:1 to 30:1. In other words, a large amount of liquid to be treated flows through the circulation flow path 30, and a smaller amount of liquid to be treated returns to the tank 10. The liquid to be treated is supplied to the filter device 20 at a high linear velocity in the circulation flow path 30, but if a large amount of liquid to be treated were returned to the tank 10 at the same high linear velocity, the liquid to be treated temporarily stored in the tank 10 would foam noticeably. However, since only a small portion of the liquid to be treated discharged from the filter device 20 is returned to the tank 10, foaming of the liquid to be treated in the tank 10 can be suppressed even if a high linear velocity is maintained.

[0046] Furthermore, the treatment system 1 for the liquid to be treated includes a return control valve 60 that adjusts the opening of the second flow path 32 so that the ratio of the amount of permeate to the flow rate of the liquid to be treated returning to the tank 10 is 1:3 to 1:10. In this way, it is preferable to have at least a greater flow rate returning to the tank 10 (hereinafter referred to as the return flow rate) than the amount of permeate. If the amount of permeate < the return flow rate, a portion of the liquid to be treated whose concentration has increased in the circulation flow path 30 will be returned to the tank 10, and the liquid to be treated in the tank 10 with a lower concentration will be returned to the circulation flow path 30. This prevents the concentration of the liquid to be treated in the circulation flow path from rising too high.

[0047] Conversely, if the permeate volume is less than the return flow rate, the effect of concentration by the filter device 20 becomes stronger, increasing the concentration of the liquid being treated in the circulation channel 30 and reducing the filtration efficiency.

[0048] To suppress such a rise in concentration, the return flow rate can be increased, which improves filtration efficiency. However, increasing the return flow rate requires a corresponding increase in the flow rate of the liquid to be treated supplied from the tank 10 to the pump 40. To achieve such a flow rate, it becomes necessary to install a pump in the first flow path section 31a.

[0049] In this way, a permeate flow rate to return flow rate ratio of 1:3 to 10 is preferable, which ensures a reasonable level of filtration efficiency (the return flow rate is not too low) and eliminates the need to install a pump in the first flow path section 31a (the return flow rate is not too high).

[0050] Furthermore, if a pump is installed in the first flow path section 31a, if the flow rate of the liquid to be treated fluctuates for any reason, it will take time to converge to the set value Floop(SV). However, since the processing system 1 controls only one pump 40, it is possible to keep the high linear velocity flow rate constant with relatively simple control, and fluctuations in the flow rate of the liquid to be treated can be quickly brought under control.

[0051] Furthermore, it is preferable that the treatment system 1 for the liquid to be treated maintains a linear velocity of the liquid to be treated between 3 and 10 [m / sec].

[0052] While embodiments of the present invention have been described above, the present invention is of course not limited to the embodiments described above, and additions, omissions, substitutions, and other modifications to the configuration are possible without departing from the spirit of the present invention.

[0053] The pressure gauge 42 described above is an example of the pressure measuring means described in the claim, but is not limited to the pressure gauge 42. The pressure measuring means may be a device that directly obtains the inlet pressure, such as the pressure gauge 42, or it may be a configuration that indirectly obtains the inlet pressure from the circulating flow rate.

[0054] For example, the correlation between the circulating flow rate of the circulation channel 30 and the inlet pressure is obtained in advance. This correlation is digitized in the form of a relational expression or correspondence table that represents the relationship between the circulating flow rate and the inlet pressure. The control device 50 obtains the inlet pressure based on the circulating flow rate obtained by the first flow meter 41 and the said relational expression or correspondence table. The inlet pressure obtained in this way is considered to be the current value of the inlet pressure. Subsequent control of the circulating flow rate is the same as described above. In this case, the first flow meter 41, the correlation between the circulating flow rate and the inlet pressure, and the calculation processing using this correspond to the pressure measuring means. [Explanation of Symbols]

[0055] A...Primary side, B...Secondary side, 1...Processing system, 10...Tank, 20...Filter device, 30...Circulation channel, 40...Pump, 50...Control device

Claims

1. A tank for storing the liquid to be treated, Filter device and A first flow path for supplying the liquid to be treated from the tank to the filter device, A second flow path for supplying the liquid to be treated from the filter device to the tank, A third channel delivers the liquid to be treated from a branching point in the middle of the second channel to a merging point in the middle of the first channel, A pump positioned between the confluence section and the filter device, The system includes a control device that controls the pump so that the flow rate of the liquid to be treated, which flows through the circulation path composed of the first, second, and third channels, remains constant. A treatment system for a liquid to be treated, characterized by the above.

2. In the treatment system for the liquid to be treated according to claim 1, The first flow path is equipped with a flow meter and pressure measuring means located upstream of the filter device. The control device controls the pump so that the flow rate of the liquid to be treated, as measured by the flow meter, becomes a set flow rate value. When the pressure measured by the pressure measuring means exceeds a predetermined value, the set flow rate is reduced by a predetermined amount. A treatment system for a liquid to be treated, characterized by the above.

3. In the treatment system for the liquid to be treated according to claim 1, The system includes a control valve that adjusts the opening of the second flow path so that the ratio of the flow rate from the branching section to the merging section to the flow rate from the branching section to the tank is between 20:1 and 30:

1. A treatment system for a liquid to be treated, characterized by the above.

4. In the treatment system for the liquid to be treated according to claim 1, The system includes a control valve that adjusts the opening of the second flow path so that the ratio of the flow rate of the liquid to be treated that has passed through the filter device to the flow rate of the liquid to be treated that enters the tank is between 1:3 and 1:

10. A treatment system for a liquid to be treated, characterized by the above.

5. In the treatment system for the liquid to be treated according to claim 1, The linear velocity of the liquid to be processed in the aforementioned filter device is 3 to 10 [m / sec]. A treatment system for a liquid to be treated, characterized by the above.

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