Treatment system for liquid to be treated

Abstract

A system for treating a liquid to be treated is provided, which can suppress fluctuations in flow rate and inhibit bubbling of the liquid to be 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 transporting the liquid to be treated from a branching point P midway through the second flow path 32 to a junction Q midway through the first flow path 31, a pump 40 arranged between the junction 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 circulating through a circulation flow path 30 consisting of the first flow path section 31b, the second flow path section 32a and the third flow path 33 is constant.

Description

[Technical field]

[0001] The present invention relates to a treatment system capable of continuously filtering a liquid to be treated 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 flow path, and the liquid to be processed is filtered while being circulated, and concentrated and purified. Recently, such processing systems are required to supply the liquid to be processed to the filter device at a high linear velocity from the viewpoint of shortening the processing time, etc.

[0003] However, as the treatment progresses and the treated liquid becomes more concentrated, the concentration of the treated liquid increases. If the treatment is continued at the same linear velocity as the initial one despite the increased concentration, the pressure at the inlet of the filter device will increase too much. For example, there is a risk that the pressure will exceed the pressure allowed by the filter device. In addition, when the treated liquid is returned to the tank from the circulation flow path, the treated liquid will foam in the tank. Such foaming can occur more significantly at higher linear velocities. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-130072 A Summary of the Invention [Problem to be solved by the invention]

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

[0006] A first aspect for achieving the above-mentioned object is a treatment system for a liquid to be treated, comprising a tank for storing the liquid to be treated, a filter device, a first flow path for transporting the liquid to be treated from the tank to the filter device, a second flow path for transporting the liquid to be treated from the filter device to the tank, a third flow path for transporting the liquid to be treated from a branching portion midway through the second flow path to a junction midway through the first flow path, a pump disposed between the junction and the filter device, and a control device for controlling the pump so that the flow rate of the liquid to be treated circulating through a circulation flow path consisting of the first flow path, the second flow path, and the third flow path is constant. Effect of the Invention

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

[0008] [Figure 1] 1 is a schematic configuration diagram of a treatment system for a liquid to be treated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 1 is a schematic diagram of a treatment system for a liquid to be treated according to the present 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 flow path 30, a pump 40, various control valves, and a control device 50 that controls the pump 40, the control valves, etc.

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

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

[0012] The filter device 20 includes a filter 21, and the upstream side of the filter 21 to which the liquid to be treated is supplied is referred to as a primary side A, and the opposite side is referred to as a secondary side B. Although the treatment system 1 is illustrated as including one filter device 20, the number of filter devices is not limited.

[0013] The filter device 20 is a device that filters the liquid to be treated with a filter 21 by a cross-flow method. The filter 21 is appropriately selected according to the desired purpose. Examples of the filter 21 include a ceramic NF membrane with a fractionation performance of several hundred to several thousand daltons, a ceramic MF membrane of 10 nm to 2 μm, a ceramic UF membrane of 1 kdalton to 300 kdalton and 5 nm, an organic NF membrane of several hundred daltons, an organic UF membrane of 1 kdalton or more, and an organic MF membrane of 0.1 μm or more. The NF membrane is a nanofilter membrane, the MF membrane is a precision filter membrane, and the UF membrane is an ultrafiltration membrane.

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

[0015] The tank 10 and the filter device 20 are connected by piping so that the liquid to be treated circulates. Specifically, the treatment system 1 includes 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 formed of piping for sending the liquid to be treated from the tank 10 to the filter device 20. The second flow path 32 is a flow path formed of piping for sending the liquid to be treated from the filter device 20 to the tank 10. The third flow path 33 is a flow path formed of piping for sending the liquid to be treated from a branching point P in the middle of the second flow path 32 to a junction Q in the middle of the first flow path 31.

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

[0018] In the second flow path 32, the portion from the filter device 20 to the branching point P is also referred to as a second flow path section 32a, and the portion from the branching point P to the tank 10 is also referred to as a second flow path section 32b.

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

[0020] Between the junction Q and the filter device 20, i.e., in the first flow path section 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 disposed upstream of the pressure gauge 42 (on the pump 40 side), but the opposite may be true. The pump 40 is a device that pumps the liquid to be treated to the filter device 20, and the method is not particularly limited. The first flow meter 41 is a device that measures the flow rate of the liquid to be treated upstream of the filter device 20, and the flow rate can be referenced by the control device 50. The pressure gauge 42 is a device that measures the pressure of the liquid to be treated upstream of the filter device 20, and the pressure can be referenced 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 is hereinafter also referred to as the inlet pressure. The output of the pump 40 is controlled by a 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 flowmeter 41 and the pressure of the pressure gauge .

[0021] Further, a fourth flow path branched from the first flow path portion 31b is provided between the pump 40 and the filter device 20. A switching valve 35 is provided between the first flow path portion 31b and the fourth flow path .

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

[0023] Between the branching part P and the tank 10, i.e., in the second flow path part 32b, a return amount control valve 60 is provided on the tank 10 side, and a second flow meter 61 is provided on the branching part P side. The return amount control valve 60 is a valve device provided in the second flow path part 32b, and the opening degree is controlled by the control device 50. By controlling this opening degree, it is possible to change the ratio of the flow rate from the branching part P to the junction part Q and the flow rate from the branching part P to the tank 10. The second flow meter 61 is a device that measures the flow rate flowing through the second flow path part 32b, and the flow rate can be referred to by the control device 50.

[0024] In the treatment system 1 configured as described above, the liquid to be treated is sent from the tank 10 and the third flow path 33 to the pump 40, and is pressure-fed by the pump 40 to the filter device 20. Note that the liquid is sent from the tank 10 to the pump 40 by the weight of the liquid to be treated stored in the tank 10, but the liquid sending form is not limited to this. 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 the filter 21 is sent as a permeated liquid from the secondary side B to a permeated liquid pipe 22. On the other hand, the liquid to be treated that has not been filtered by the filter device 20 is discharged to a second flow path 32.

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

[0027] In this way, after the liquid to be treated is filtered by the filter device 20, a part of the liquid circulates through the circulation flow path 30 and the remainder returns to the tank 10, thus performing circulatory filtration. During this circulatory filtration, the switching valve 35 is closed so that the liquid to be treated does not flow into the fourth flow path 34.

[0028] Such circulation filtration is controlled by a control device 50. The control device 50 is also called a programmable controller or a sequencer. The control device 50 includes a CPU, a memory, and the like, and reads and executes a control program stored in the memory. The number of control devices 50 is not limited to one, and the control described below may be performed by multiple devices.

[0029] The control by the control device 50 will be specifically described below. The control device 50 executes a control program to control the pump 40 so that the linear velocity of the liquid to be treated at the inlet of the filter device 20 becomes a high linear velocity. The linear velocity is 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. The high linear velocity is set appropriately according to the properties of the liquid to be treated and the configuration of the filter 21, and is preferably 3 to 10 m / sec.

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

[0031] Floop (PV) is the current value of the flow rate of the liquid to be treated in the first flow path section 31b (hereinafter, the circulation flow rate). Specifically, Floop (PV) is the current value of the circulation flow rate measured by the first flow meter 41. Floop (SV) is a set value for the circulation flow rate.

[0032] Fret(PV) is the current value of the flow rate returning to the tank 10 (hereinafter, the return flow rate) out of the circulation 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 that 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 a set value for the inlet pressure. As an example of Pin(SV), an upper limit pressure allowed for the filter device 20 is set.

[0034] The flow rate (set flow rate Floop (SV)) measured by the first flow meter 41 is set to 200 [m 3 The liquid to be treated is filtered by the filter device 20, and the amount of liquid that passes through the filter 21 (hereinafter, the permeated liquid amount) is 2 [m 3 / h]. The flow rate of the treated liquid discharged from the filter device 20 is 198 [m 3 / h]. A portion of this flows from branch point P to junction Q, and the flow rate is 192 [m 3 / h], and the remainder flows from the branch point P to the tank 10, and the flow rate is 6 [m 3 The flow rate of the liquid to be treated supplied from the tank 10 to the junction Q is 8 [m 3 / h]. From the junction Q to the pump 40, 200 [m 3 / h] of the treated liquid flows in.

[0035] The filter device 20 is 200 mm 3 The treated liquid is supplied at a flow rate of 2 [m 3 / h] is discharged from the circulation flow path 30, concentrating the liquid being treated. The filter device 20 reduces the liquid being treated by the amount of the permeation flow rate, but the liquid being treated is added from the tank 10, so that an almost constant amount of the liquid being treated is supplied to the inlet side of the pump 40. In this way, the circulation flow path 30 steadily discharges 200 [m 3 / h] of the liquid to be treated can be supplied to the filter device 20.

[0036] The control device 50 performs PID control of the output of the pump 40 so that the initially set Floop (SV) is obtained. Through the PID control, a basically 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 Art section, if the treatment is continued at the same linear velocity as the initial one even though the concentration has increased as the treatment progresses, the pressure at the inlet of the filter device will increase too much.

[0037] Therefore, when the control device 50 detects that the current value of the inlet pressure, Pin (PV), has exceeded the set upper limit pressure, Pin (SV), the control device 50 lowers the set value Floop (SV). The control device 50 PID controls the output of the pump 40 so that the current value Floop (PV) becomes the updated set value Floop (SV). In other words, the output of the pump 40 is lowered. This prevents the inlet pressure of the filter device 20 from exceeding the upper limit even if concentration by the filter device 20 progresses, and the flow rate of the treated liquid flowing through the circulation flow path 30 can be stabilized. There is no particular limit to the degree to which the set value Floop (SV) is lowered. For example, a value lowered by a predetermined amount or rate based on the initial set value Floop (SV) can be set as the new set value Floop (SV).

[0038] By controlling the pump 40 in this way, the circulation flow rate of the treated liquid is maintained at the set value Floop(SV). The controller 50 also PID controls the opening of the return amount control valve 60 so that the current value Fret(PV) of the flow rate from the branch point P to the tank 10 becomes the set value Fret(SV). By such control, a part of the treated liquid returns to the junction Q and the remainder returns to the tank 10, and the ratio of the part to the remainder is kept constant.

[0039] In this way, the flow rate of the liquid to be treated flowing through the circulation flow path 30 can be stabilized, so that the liquid to be treated can be supplied to the filter device 20 at a constant high linear velocity. Also, although a portion of the liquid to be treated is returned to the tank 10, the flow rate is much less than the flow rate in the circulation flow path 30. In the example of FIG. 1, the flow rate returning to the tank 10 is 6 [m 3 / h], and the flow rate through the circulation flow path 30 is 200 (198 in the second flow path section 32a, and 192 in the third flow path 33). Since only a small amount of the liquid to be treated is returned to the tank 10 in this way, it is possible to suppress the generation of bubbles when the liquid to be treated is released into the tank 10. As described above, the flow rate of the liquid to be treated flowing through the circulation flow path 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. Since there is little fluctuation in the flow rate, it is possible to further suppress foaming caused by the liquid to be treated being returned to the tank 10.

[0040] The concentration of the liquid to be treated is continued by circulating filtration, and when the liquid to be treated reaches a predetermined concentration, the circulating filtration is stopped. After that, the next process may be performed. The return amount control valve 60 is closed, and the liquid to be treated is circulated and filtered in the circulation flow path 30 without being returned to the tank 10. At this time, the amount of the liquid to be treated that corresponds to the amount of the permeated liquid that has permeated the filter device 20 is supplied from the tank 10 to the circulation flow path 30. This further increases the concentration of the liquid to be treated in the processing system 1, and the liquid can be concentrated to the limit of the concentration that can be delivered by the pump 40. This type of process cannot be performed when a pump is provided in the first flow path section 31a.

[0041] In addition, whether the liquid to be treated has reached the predetermined concentration can be determined, for example, by regarding the liquid to be treated as having reached the predetermined concentration when the liquid stored in the tank 10 is reduced and reaches a predetermined amount. Alternatively, the liquid to be treated in the first to third flow paths 31 to 33 may be sampled to measure the concentration and determine whether the concentration is the predetermined concentration. Then, after the liquid to be treated has reached the predetermined concentration through circulation filtration, the control device 50 opens the switching valve 35. Then, the pump 40 is operated to send the liquid to be treated in the first to third flow paths 31 to 33 to the fourth flow path 34. The fourth flow path 34 is connected to various devices for treating the liquid to be treated, such as an aseptic tank or a filling machine. In this way, the liquid to be treated having the predetermined concentration is sent to various devices for the next process.

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

[0043] By controlling the pump 40 in this way, the flow rate of the treated liquid supplied to the filter device 20 through the circulation flow path 30 can be stabilized, and the flow rate of the treated liquid returning to the tank 10 can also be stabilized with little fluctuation. Therefore, even if the treated liquid is returned from the circulation flow path 30 to the tank 10 in which the treated liquid is temporarily stored, foaming can be suppressed.

[0044] The treatment system 1 for the treated liquid also includes a first flowmeter 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 treated liquid measured by the first flowmeter 41 becomes 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 circulation flow rate by a fixed amount. By such control, even if concentration progresses in the circulation flow path 30 and the concentration of the treated liquid increases, the flow rate of the treated liquid flowing through the circulation flow path 30 can be stabilized without exceeding the set value Pin (SV) of the pressure.

[0045] The treatment system 1 for the liquid to be treated is also provided with a return amount control valve 60 that adjusts the opening of the second flow path section 32b so that the ratio of the flow rate from the branching section P to the junction section Q to the flow rate from the branching section P to the tank 10 is 20:1 to 30:1. That is, a large amount of the liquid to be treated flows through the circulation flow path 30, and a smaller amount of the 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 through the circulation flow path 30. If a large amount of the liquid to be treated is returned to the tank 10 while maintaining the high linear velocity, the liquid to be treated temporarily stored in the tank 10 will foam significantly. However, since only a small amount 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] The treatment system 1 for the treated liquid also includes a return control valve 60 that adjusts the opening of the second flow path 32 so that the ratio between the amount of permeated liquid and the flow rate of the treated liquid returning to the tank 10 is 1:3 to 1:10. In this way, it is preferable to make the flow rate returning to the tank 10 (hereinafter, the return flow rate) greater than the amount of permeated liquid. When the amount of permeated liquid is less than the return flow rate, a part of the treated liquid whose concentration has increased in the circulation flow path 30 is returned to the tank 10, and the treated liquid in the tank 10 whose concentration is lower than that is returned to the circulation flow path 30. This prevents the concentration of the treated liquid in the circulation flow path from increasing too much.

[0047] Conversely, the amount of permeated liquid >When the return flow rate is used, the effect of concentration by the filter device 20 is strong. As a result, the concentration of the liquid to be treated in the circulation flow path 30 increases, and the filtration efficiency decreases.

[0048] In order to suppress such an increase in concentration, the return flow rate should be increased, and the filtration efficiency will increase. However, if the return flow rate is increased, the flow rate of the treated liquid supplied from the tank 10 to the pump 40 must also be increased accordingly. To achieve such a flow rate, it becomes necessary to provide a pump in the first flow path section 31a.

[0049] In this way, it is preferable that the permeation flow rate:return flow rate ratio be 1:3 to 10 so that a considerable degree of filtration efficiency is ensured (the return flow rate is not too small) and a pump is not required in the first flow path section 31a (the return flow rate is not too large).

[0050] Furthermore, when a pump is provided in the first flow path section 31a, if the flow rate of the liquid to be treated fluctuates for some reason, it takes time for the flow rate to converge to the set value Floop (SV). However, since the processing system 1 controls one pump 40, it is possible to relatively simply control the flow rate at high linear velocity to be constant, and also to quickly converge the fluctuation in the flow rate of the liquid to be treated.

[0051] In addition, in the treatment system 1 for the liquid to be treated, the linear velocity of the liquid to be treated is preferably set to 3 to 10 [m / sec].

[0052] Although an embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above-described embodiment, and addition, omission, substitution, and other modifications of 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 in the claims, but is not limited to the pressure gauge 42. The pressure measuring means may be a device that directly obtains the inlet pressure, like the pressure gauge 42, or may be configured to indirectly obtain the inlet pressure from the circulation flow rate.

[0054] For example, the correlation between the circulation flow rate of the circulation flow path 30 and the inlet pressure is obtained in advance. The correlation is converted into electronic data in the form of a relational equation or a correspondence table that expresses the relationship between the circulation flow rate and the inlet pressure. The control device 50 obtains the inlet pressure based on the circulation flow rate obtained by the first flow meter 41 and the relational equation or the correspondence table. The inlet pressure obtained in this manner is regarded as the current value of the inlet pressure. The subsequent control of the circulation flow rate is similar to that described above. In this case, the first flow meter 41, the correlation between the circulation flow rate and the inlet pressure, and the calculation process using this correspond to the pressure measurement means. [Explanation of symbols]

[0055] A... primary side, B... secondary side, 1... treatment system, 10... tank, 20... filter device, 30... circulation flow path, 40... pump, 50... control device

Claims

1. A tank for storing the liquid to be treated; A filter device; a first flow path for transferring the liquid to be treated from the tank to the filter device; a second flow path for transferring the liquid to be treated from the filter device to the tank; a third flow path that sends the liquid to be treated from a branching portion in the middle of the second flow path to a joining portion in the middle of the first flow path; a pump disposed between the junction and the filter device; a control device that controls the pump so that a flow rate of the liquid to be treated flowing through a circulation flow path formed by the first flow path, the second flow path, and the third flow path is constant; and a flow meter and a pressure measuring means provided upstream of the filter device in the first flow path; a control valve for adjusting an opening degree of the second flow path so that a ratio of a flow rate of the liquid to be treated that has passed through the filter device to a flow rate of the liquid to be treated that is introduced into the tank is 1:3 to 1:10; the control device controls the pump so that the flow rate of the liquid to be treated measured by the flow meter becomes a set flow rate value; When the pressure of the pressure measuring means exceeds a predetermined value, the set flow rate value is reduced by a predetermined amount. A treatment system for a liquid to be treated.

2. 2. The system for treating a liquid to be treated according to claim 1, a control valve that adjusts the opening degree of the second flow path so that the ratio of the flow rate from the branching portion to the joining portion and the flow rate from the branching portion to the tank is 20:1 to 30:1 A treatment system for a liquid to be treated.

3. 2. The system for treating a liquid to be treated according to claim 1, The linear velocity of the liquid to be treated in the filter device is 3 to 10 [m / sec]. A treatment system for a liquid to be treated.

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