JPS6054081B2 - liquid filtration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precoat type filtration device for waste liquid purification treatment, and in particular, an automatic filter system that optimizes the flow rate of a filtered liquid by measuring the differential pressure before and after the filter body. The present invention relates to a filtration device with a control function.

The precoat type filtration device uses filter aids such as
Diatomites, natural fibers, etc. as filter aid retention structures, e.g.
By using the flow of the liquid to be filtered and entwining it with the Jiyonson Screen (trade name), a filter is formed, and when the filter becomes contaminated, the flow of the liquid to be filtered is reversed. , which is configured to flush out the dirt trapped therein together with the filter aid, and the operation of re-forming the filter body instead of replacing the filter body is extremely simple.
It is widely used today. However, in such precoat type filtration devices, the pressure difference between the pressure of the filtrate before passing through the filter and the pressure of the filtrate after passing through the filter is one of the dominant factors in the purification effect. It is known that

That is, in order to increase the purification processing speed, if the flow rate of the filtrate is increased and the differential pressure is made excessive, the rate at which the filth in the filtrate leaks into the filtrate increases; On the other hand, if the flow rate of the filtrate is reduced in order to suppress the increase in the leakage rate of the filth, the increase in the differential pressure can be suppressed, but the total period of the purification process becomes longer, resulting in inefficiency. It is something that becomes. Therefore, when operating a conventional precoat type filtration device, the flow rate of the liquid to be filtered is kept constant until the above-mentioned differential pressure reaches a specified value, which in a typical device example is a value of about 1 to 1.5 kg/Clt. When the specified value is exceeded, the flow rate of the filtrate is manually reduced to prevent a sudden rise in the differential pressure, thereby capturing waste during the total period of purification treatment. There was a request to increase the amount.

Such manual operation for adjusting the flow rate requires dealing with the differential pressure that increases from moment to moment while being controlled by the properties and concentration of the waste, the performance of the filter aid, and the flow rate of the liquid to be filtered. Therefore, not only is the driving operation complicated, but also the operation requires constant monitoring work. In view of the problems such as the complexity of flow rate control based on the above-mentioned prior art, it is an object of the present invention to divide the period of purification into two stages: a first control stage in constant flow rate control mode, and a constant pressure differential pressure mode. The above drawbacks are eliminated by dividing the control mode into a second control stage and automatically controlling the flow rate of the filtrate in each control stage, and also automatically transitioning between each control stage. Therefore, it is an object of the present invention to provide an excellent precoat-type filtration device that eliminates complicated manual operations and monitoring work for such operations, and can further reduce the frequency of precoat treatment of the filter body. be.

In accordance with the above object, the present invention has a configuration in which the flow rate of the liquid to be filtered is measured by a flow rate measuring means to obtain a flow rate signal representing the flow rate value, and further, the pressure of the liquid to be filtered introduced into the liquid to be filtered chamber is measured. , the differential pressure between the pressure of the filtrate and the pressure of the filtrate led out from the filtrate chamber via the filter body is measured by the differential pressure measuring means, and a differential pressure signal representing the measured value is obtained. In response to a control mode signal representing a flow rate control mode and a flow rate target value signal representing a flow rate target value, constant flow rate control is performed such that the flow rate of the filtrate matches the flow rate target value, or;
In response to a control mode signal representing a constant differential pressure mode and a differential pressure target value signal representing a differential pressure target value, a constant differential pressure is established such that the differential pressure between the filtrate and the filtrate matches the differential pressure target value. When operating the filtration device, after the start of operation, the first control stage is stored in the control stage storage means until the differential pressure measured by the differential pressure measuring means reaches the target differential pressure value. In response, the first control stage setting means supplies a control mode signal representing the constant flow control mode and a flow rate target value signal representing the flow rate target value to the flow rate adjusting means. The adjusting means executes the first control stage control, that is, the constant flow control described above, and then the control stage changing means detects that the differential pressure measured by the differential pressure measuring means has increased to the differential pressure target value. When detected, the second control stage is stored in the control stage storage means, and in response, the second control stage setting means sets the flow rate adjusting means to:
By supplying a control mode signal representing the constant differential pressure control mode and a differential pressure target value signal representing the differential pressure target value, the adjusting means is caused to perform the second control stage control, that is, the constant differential pressure control described above. The gist of this is that it is executed.

An embodiment of the present invention will be described below based on FIGS. 1 to 6. FIG. 1 is a block diagram showing the configuration of its hardware, and the filtration device 1 includes a filtrate chamber 1a into which a filtrate is introduced, a filtrate chamber 1b from which a filtrate is taken out, and both chambers. Filter body 1c interposed between 1a11b
The filter body 1c has a filter aid 1C entwined with a Jeonson Screen (trade name) 1C' as a mesh body.
” is formed by

A waste liquid pipe 2 extends from a waste liquid tank (not shown) into the filtered liquid chamber 1a, and a waste liquid pump 3 and a flow rate adjustment section 4 are inserted into the waste liquid pipe 2 in this order from the waste liquid tank side. A conduit 5 extends from the filtrate chamber 1b toward a purification device for the next process (not shown), for example, a demineralization tower, and a flow rate measuring section 6 is inserted into the conduit 5. An output terminal for outputting a signal is connected to the flow rate adjustment section 4. Further, pressure impulse pipes 7 and 8 extend from the waste liquid pipe 2 between the flow rate adjustment unit 4 and the filtration device 1 and the conduit 5 between the filtration device 1 and the flow rate measurement unit 6, respectively, and are connected to the differential pressure measurement unit 9. An output terminal for outputting a differential pressure signal from the differential pressure measuring section 9 is connected to the flow rate adjusting section 4. The arithmetic processing unit 10 includes a microprocessor and has four input ports and three output ports. Among the input boats mentioned above, boat 1 is for the ready-to-operate state signal S1, and is connected to the power supply through a resistor 10a, as well as a switch SWl'' that is linked to the ready-to-operate setting switch SW1.
grounded through.

The boat 2 is for the operating state signal S2, and is connected to a power source through a resistor 10b, and is grounded through a switch SW/ that is interlocked with the operational state setting switch SWl. The boat 2 is for an operating state signal S2, and is connected to the power supply through a resistor 10b, and has a switch SWl'' that is linked to the operable state setting switch SWl and a switch SW2' that is linked to the pump start switch SW2. grounded through. The boat 3 is for the flow rate signal (2) and is connected to the output terminal of the flow rate measuring section 6. The boat 4 is for the differential pressure signal S6, and is connected to the output terminal of the differential pressure measuring section 9. Furthermore, among the output boats, boat 5, boat 6, and boat 7 each receive a flow rate target value signal S4 representing a flow rate target value.
, for the differential pressure target value signal S7 representing the differential pressure target value and the control mode signal S3, and are connected to the input terminals of the flow rate adjustment section 5, respectively.

On the other hand, one end of a conduit 11 is connected to the flow rate measurement unit 6 and the upstream conduit 5, and the other end of the conduit 11 is connected to the suction port of the holding pump 13.

A discharge port of the holding pump 13 is connected to one end of a conduit 14, and the other end of the conduit 14 is connected to the waste liquid pipe 2 downstream of the flow rate adjustment section 4 to form a holding loop. Further, the other end of the conduit 12 connected to the conduit 5 near the conduit 11 opens into a precoat tank 15 for storing precoat, and a cock 16 is provided in the conduit 12.

The precoat tank 15 communicates with a suction port of a precoat pump 18 through a conduit 17 serving as an introduction pipe, and one end of a conduit 19 is connected to a discharge port of the precoat pump 18 . The other end of the conduit 19 is connected to the waste liquid pipe 2 downstream of the flow rate adjustment section 4 to form a precoat loop. The waste liquid pump 3 and the holding pump 13 are connected to electric motors 20 and 21, respectively, and the electric motor 21 for the holding pump 13 is connected to the electric motor 2 for the waste liquid pump 3 through an operation enable state setting switch SWl.
0 can be connected to a power source (not shown) through the pump start switch SW2 and the operable state setting switch SWl, respectively.

On the other hand, the precoat pump 18 is connected to an electric motor 22, which can be connected to a power source (not shown) through a precoat switch SW3.
A backwash pipe 23 is opened in a, and a backwash valve 24 is provided in the backwash pipe 23. A functional block diagram (claim correspondence diagram) showing the connection relationship between the function realizing means corresponding to each of the plurality of functions performed by the microprocessor in the arithmetic processing unit 10 in FIG. 1 and the hardware components is shown in the second figure. It is a diagram.

In the figure, the function realizing means in the arithmetic processing unit 10 includes a control stage storage means 10A, a first control stage setting means 10B following the storage means 10A via a first control stage information line 11, and a control stage setting means 10B. It consists of a control stage changing means 10C preceding the storage means 10A via a change information line 12, and a second control stage setting means 10D following the storage means 10A via a second control stage information line 13. From the first control stage setting means 10B, a constant flow control mode information line 16
and a flow rate target value information line 17 extend to the flow rate adjustment section 5, and from the second control stage setting means 10D, a constant differential pressure control mode information line 18 and a differential pressure target value information line 1, It extends to the adjustment section 5.

The input terminal of the control stage changing means 10C is connected to the differential pressure measuring section 9.

Note that other hardware components are the same as those indicated by the same reference numerals in FIG. The operation of the above configuration is explained in FIGS. 3 to 5, which are flowcharts of the arithmetic processing unit 10, and FIG.
The explanation will be as follows with reference to the drawings.

First, prior to the start of operation of the filtration device, preparatory work for re-forming the filter body 1c in the filtration device 1 is performed.

To do this, the backwash valve 24 in the backwash pipe 23 is opened to cause the filtrate in the filtrate chamber 1b to flow back into the filtrate chamber 1a, so that the The filter aid 1C'' is dropped together with the captured material and flows out of the filtration device 1 through the backwash pipe 23. Next, the backwash valve 24 is closed to return the filtrate chamber 1a1 and the filtrate chamber 1b to a full state, and then, after opening the cock 16,
When the pre-coat switch SW is closed and power is supplied to the electric motor 22 to drive the pre-coat pump 18, the unused filter aid 1C'' stored in the pre-coat tank 15 is transferred to the conduit 17 and the conduit 19 together with water as a carrier. The unused filter aid 1C'' passes through a part of the pre-coat loop containing the waste liquid pipe 2 and is fed under pressure into the filtrate chamber 1a, and the unused filter aid 1C'' gets entangled with the bare Johnson Screen (trade name) 1C. The water as carrier is collected from the filtrate chamber 1b into the precoat tank 15 through the remaining part of the precoat loop including conduit 5 - conduit 12 - cock 16 .

When the backwash processing work and the precoat processing work are completed, the operation ready state setting switch SWl is closed, power is supplied to the electric motor 21 for the holding pump 13, and after starting the holding pump 13, the precoat switch SW3 is closed. is opened to stop the precoat pump 18.

As a result, when the holding pump 13 is started,
Water containing filter aid from the pre-coat pump 18 and water from the holding pump 13 are simultaneously pumped into the filtrate chamber 1a, but after the pre-coat pump 18 is stopped, the water containing the filter aid in the filtrate chamber 1b is Only water is pressurized by the holding pump 13 and discharged from the conduits 5, 11, 14 and part of the waste pipe 2. Tour the Holdein Group. The parallel operation of the pre-coating pump 18 and the holding pump 13 immediately after the completion of the pre-coating process is due to an extreme decrease in the flow rate of the filtered liquid passing through the filter body 1c when transitioning from the pre-coating process to the purification process. This is necessary to prevent the filter aid from falling off. After the precoat pump 18 stops, the flow rate of the liquid to be filtered passing through the filter body 1c decreases to the holding flow rate by the holding pump 13, but this holding flow rate is equal to It is sufficient to maintain the engagement force with respect to the filtrate chambers 1a and 1b, and the value is selected to be considerably smaller than that during the purification process described later. This is a fairly small value (
Figure 6Aa). Meanwhile, during this time, when a reset signal is sent to the microprocessor in the arithmetic processing unit 10 to start it, the arithmetic processing unit 10 executes a program whose flowcharts are shown in FIGS. 3 to 5. .

First, the arithmetic processing unit 10 that has started (FIG. 3a) reads the operable state signal S1 from the boat 1 into the D register (FIG. 3b).

By the way, as mentioned above, during the period when backwash processing work and precoat processing work are being performed, the operation ready state setting switch SWl is open and the switch SW/ is closed in conjunction with this, so that the operation is not possible. The enable state signal S1 is ROJ (Fig. 6Bb), but as mentioned above, when starting the purification process, the operable state setting switch SWl is closed, and in conjunction with this, the switch SW/ is closed. Because we will develop
The signal S1 is inverted to RlJ.

(Figure 6Bc). Therefore, the arithmetic processing unit 10 determines whether or not the contents of the D register, that is, the operable state signal S1 is ROJ (FIG. 3c), and when the determination result is YES, that is, backwashing processing is performed. During the pre-coating process, the process returns to the process shown in FIG. 3b and waits until the signal S1 becomes RlJ while repeating the subsequent processes (FIG. 3b-c). When the judgment result (Fig. 3 c) is NO, that is, when the device is in the operable state, the E register is cleared (Fig. 3 d), and then, from boat 1, the device is again in the operable state. Read signal S1 to D register (Figure 3e)
, determine whether or not this is ROJ (Figure 3 f), and if the determination result is YES, return to the process in Figure 3 b and repeat the subsequent processes (Figure 3 b-f). while waiting until the signal S1 becomes RlJ. The judgment result (Fig. 3 f)
) is NO, then the operation status signal ■ is read from the boat 2 to the accumulator (Fig. 3g). At this time, during the pre-coating process and the holding operation immediately thereafter, the pump start switch SW2 is opened, and in conjunction with this, the switch SW2'' is closed, so the operating status signal ■ becomes ROJ. (Cd in FIG. 6), when both the operable state setting switch SWl and the pump start switch SW2 are closed to start the purification work, the operating state signal S2 is inverted to RlJ, and from then on, during the purification work Rl
J (Fig. 6Ce).

Therefore, the processing unit 10 determines whether the signal S2 is RlJ (Fig. 3h), and when the determination result is NO, that is, when the holding operation is still being performed, the processing section 10 determines whether the signal S2 is RlJ or not. Returning to the step in Figure 3e, the subsequent processing (third
While repeating the steps in Figures e to h), wait until both the operable state signal S1 and the operating state signal S2 become RlJ.

Then, both the operable state switch SWl and the pump start switch SW2 are closed, and the determination result (FIG. 3F,
．． h) is NO, . If YES, then E
Determine whether the register is RO (Figure 3 1)
. At the initial stage of the purification process, the E register remains cleared in the step d in FIG. 3, so the determination result (FIG. 3 1) is YES. As described above, when the pump start switch SW2 is closed, the electric motor 20 is supplied with power and the waste liquid pump 3 is started, so that the waste liquid in the waste liquid tank is pressurized by the waste liquid pump 3, and the waste liquid pipe 2 and the flow rate adjustment section 4 are pressurized. The liquid flows into the filtrate chamber 1a through the filtrate chamber 1a. This waste liquid is purified by the filter body 1c, flows into the filtrate chamber 1b, and is further pressure-fed through the conduit 5 and the flow rate measuring section 6 to the purification device for the next process, so that the differential pressure measured by the differential pressure measuring section 9 The value rises to a larger value than that during the holding operation (
Figure 6Af). As described above, if the determination result in FIG. 3 1 is YES, the processing device 10 stores the first control step in the control step storage means (FIG. 2 10A) (FIG. 3 d). ), the first control stage information line (
The following flow is executed in response to the first control stage information provided via FIG. 2 (11).

That is, the processing unit 10 operates in the RO mode, which represents the constant flow rate control mode.
The control mode signal S of J is outputted from the boat 7 (FIG. 4 j), and then the flow rate target value F1 is read out from the 800 yard (FIG. 4 k), and the flow rate target value signal S representing this is output. ，
is output from boat 5 (Fig. 4, 1).

Through the above processing (FIG. 4 j to 1), the first control stage setting means (FIG. 2 10B) sends the constant flow control mode information line (FIG. 2 143) and the flow target value information line (FIG. 2, 17), constant flow control mode information and flow target value information are supplied.

Thus, the flow rate regulator 4 operates in constant flow control mode,
Flow rate signal that represents the actual flow rate of waste liquid, that is, the liquid to be filtered■
is received from the flow rate measurement unit 6, and the flow rate is automatically controlled so that the flow rate matches the flow rate target value F1.

As a result, during the period of the first control stage, the flow rate F of the liquid to be filtered is maintained at a constant value, which is the flow rate target value F1 (Dg in FIG. 6). During that time, the filter body 1c in the filtration device 1 is attached and deposited with the captured dirt, which causes the pressure difference between the pressure of the filtrate in the filtrate chamber 1a and the pressure of the filtrate in the filtrate chamber 1b. P gradually increases over time (Fig. 6Ah). On the other hand, during the period of the first control stage, the arithmetic processing unit 10 reads the differential pressure target W)1 from address 8001 (Fig. 4 m), and transfers this from the first control stage to the second control stage. It is stored in the L register as a reference value for determining the switching point (FIG. 4n).

Subsequently, the processing section 10 receives a differential pressure signal S6 representing the actual differential pressure between the filtrate and the filtrate from the differential pressure measuring section 9, and
This is read from the boat 4 (Fig. 4h) and stored in the C register (Fig. 4p), and then the actual It is determined whether the differential pressure P has become equal to or higher than the target differential pressure value P1 (Fig. 4q). If the determination result is NO, read the operating state signal S2 from the boat 2 again (Fig. 4r) and determine whether the signal S2 is RlJ or not.
That is, it is determined whether or not the purification process continues without starting the holding operation described below (Fig. 4, s).
.

At this time, the pump start switch SW2 is opened (sixth
If the determination result (FIG. 4 s) is NO, the process returns to the process shown in FIG. 3 e and the holding operation is performed while repeating the subsequent processes (FIG. 3 e-h). ) Now, when a holding operation is performed during the first control stage, the flow rate F of the liquid to be filtered passing through the flow rate measuring section 6 at that point is the holding flow rate F.

(Dj in Fig. 6), and correspondingly, the differential pressure P between the filtrate and the filtrate decreases to the hoarding differential pressure (0 in Fig. 6). This is caused by the holding flow rate FO of the recycled water, and changes depending on the state of adhesion and accumulation of dirt on the filter body 1C'' at the time when the holding operation is performed.

By the way, the arithmetic processing unit 10 determines that the operating state signal ■ has become ROJ during the processing of the first control stage (τ to s in FIG. 4) (FIG. 4 s), and performs the process as shown in FIG. 3 e. The process of returning to the process is as described above, but when resuming the purification process,
When the pump start switch SW2 is closed and the operating status signal ■ is inverted to RlJ (C1 in Figure 6), the determination result in Figure 3h becomes YES, and subsequently the contents of the E register are changed to RO. (FIG. 3, 1).

At this time, since the E register stores the code ROJ representing the control stage at the time when the holding operation is started, that is, the first control stage in the above operation example, the determination result (FIG. 3 1) is YES, the process proceeds to the step shown in FIG. 4j, and the purification process after the holding operation is continued in the control mode of the first control stage. In addition, during the above-mentioned holding operation, if the worker judges that it is urgently necessary to carry out backwashing work etc. and opens the operable state setting switch SWl, the operable state signal S1 is activated.
becomes ROJ and the determination result in FIG. 3f becomes YES, so the arithmetic processing unit 10 returns to the step in FIG. Wait until the transfer-enabled state signal S1 becomes RL.

In the meantime, the workers perform backwashing work, etc., and then perform precoating work again, in preparation for restarting the purification work. On the other hand, both the operable state switch SWl and the pump start switch SW2 are closed, and the operating state signal S2
If is RlJ, the determination result in FIG. 4 s becomes YES, so the arithmetic processing unit 10 returns to the step in FIG. The operation in the constant flow rate control mode is continued until the differential pressure P reaches the target differential pressure value P1.

During this period, the actual differential pressure gradually increases, and eventually the target differential pressure P
1 (Fig. 6 Am), the determination result Y is shown in Fig. 4 q.
ES, so store Rlj in the E register (4th
Figure t).

By the above processing (Fig. 4 τ to s), the control stage changing means (
From the control stage storage means (Fig. 2 10C)
Control stage change information is sent to A) via the control stage change information line (2nd?2).

Therefore, the arithmetic processing unit 10 stores the second control stage in the control stage storage means (FIG. 2 10A) (FIG. 4, t), and stores the second control stage information line (FIG. 2 13) from the storage means. The following flow is executed in response to the second control stage information provided via the second control stage information.

That is, the processing section 10 performs RL representing the constant differential pressure control mode.
A control mode signal S3 is output from the boat 7 (see Fig. 5).
), then reads the differential pressure target value P1 from the L register, and outputs the differential pressure target value signal S7 representing this from the boat 6 (FIG. 5v).

Through the above processing (Fig. 5 uv), the constant differential pressure control mode information line (second Constant differential pressure control mode information and differential pressure target value information are provided via the differential pressure target value information line (FIG. 18) and the differential pressure target value information line (FIG. 2, 1). Thus,
The flow rate adjustment section 4 operates in a constant differential pressure control mode, receives a differential pressure signal S6 representing the actual differential pressure between the filtrate and the filtrate from the differential pressure measuring section 9, and determines whether the differential pressure is the differential pressure target value. The flow rate is automatically controlled to match P1.

As a result, during the period of the second control stage, the differential pressure P between the liquid to be filtered and the filtrate is maintained at a constant value of the target differential pressure value P (sixth section An). During this time, the captured dirt continues to adhere and accumulate on the filter body 1c, so the flow rate F of the filtered liquid gradually decreases over time (D♂ in Fig. 6).
. Subsequently, the arithmetic processing unit 10 reads the operating state signal S2 from the boat 2 (FIG. 5 w) and determines whether the signal is r1, that is, whether or not the holding operation has started. Judgment (Fig. 5 x).

If the determination result is NO, the process returns to the process shown in FIG. 3e, and waits for the operating state signal S2 to be inverted to RlJ while repeating the subsequent processes (FIG. 3e to h). If a holding operation is performed during the second control stage (0, p, q in FIG. 6), the E register stores the code RlJ representing the second control stage.
When resuming purification work, the judgment result in Figure 3 1 is N.
It becomes O.

Then, the arithmetic processing unit 10 proceeds to the step shown in FIG. 5u, and the purification process after the holding operation is continued in the control mode of the second control stage. On the other hand, if the determination result shown in FIG. It is determined whether or not it is ROJ, that is, whether or not the operable state setting switch SWl is opened (FIG. 5z).

If the judgment result is NO, return to the process shown in Fig. 5 w, and continue operation in the constant differential pressure control mode while repeating the subsequent processes (Fig. 5 w - z), but if the flow rate F is It has decreased to the minimum value F2 that allows continued operation (6th ward Pr
), or the differential pressure P has increased abnormally (6th
When the worker confirms the operation state setting switch SWl after confirming the operation state setting switch SWl (FIG. 6 Bt), the determination result in FIG. Returning, the process repeats the subsequent processing (FIG. 3 b-c) and waits for the drive ready state signal S1 to be inverted to RlJ.
As described above, according to the present invention, the period of the purification process is divided into the first stage of constant flow rate control and the second stage of constant differential pressure control, and the flow rate of the liquid to be filtered in each control stage is controlled. automatically controlled,
In addition, by configuring the system to automatically transition between each control stage, it is possible to completely eliminate the manual operation required in the past to control the flow rate of the filtrate. This has the advantage that the operation becomes very simple and there is no need for constant monitoring work for the operation.
Furthermore, in the first control stage, which is not constrained by the differential pressure that has reached the specified value, the structure is configured to enable constant flow rate control for a considerably large target flow rate, which makes it possible to control the purification process. At the initial stage, high-speed purification processing is possible, which has the effect of shortening the purification processing time.

Furthermore, a control stage storage means is provided to store the control stage at the time when the holding operation was performed, and when the purification work is restarted, the purification work is continued at the stored control stage. This configuration also has the effect that even if the purification process is interrupted, the appropriate progress of the control stage can be maintained without requiring any manual operation.

[Brief explanation of the drawing]

The figures relate to an embodiment of the present invention; FIG. 1 is a block diagram showing its hardware configuration, FIG. 2 is a block diagram showing its software function implementation means,
Figures 3 to 5 are flowcharts of the program executed by the arithmetic processing unit, and Figure 6 is (4) at each control stage.
It is a time chart showing the differential pressure between the liquid to be filtered and the liquid to be filtered, (B) an operable state signal, (C) an operating state signal, and (2) the flow rate of the liquid to be filtered. 1a...Filtered liquid chamber, 1b...Filtrate chamber, 1c...Filter body, 4...Flow rate adjustment means, 6...Flow rate Measuring means, 9... Differential pressure measuring means, 10A... Control stage storage means, 10B
...First control stage setting means, 10C...
- Control stage changing means, 10D... Second control stage setting means.

Claims (1)

[Claims] 1. A filtrate chamber 1a into which a filtrate is introduced, a filtrate chamber 1b from which a filtrate is taken out, and a filter interposed to isolate the filtrate chamber 1a and the filtrate chamber 1b. 1c, a flow rate signal S representing the flow rate value is obtained by measuring the flow rate of the liquid to be filtered passing through the filter body 1c.
A flow rate measuring means 6 that outputs _5 measures the pressure difference between the pressure of the filtrate introduced into the filtrate chamber 1a and the pressure of the filtrate derived from the filtration chamber 1b, and represents the differential pressure value. In response to the differential pressure measuring means 9 that outputs the differential pressure signal S_6 and the control mode signal S_3 representing the constant flow rate control mode, the mode shifts to the constant flow rate control mode, and the flow rate target value represented by the flow rate target value signal S_4 changes. and adjust the flow rate of the filtrate to match the flow rate value of the filtrate introduced into the filtrate chamber 1a, and in response to the control mode signal S_3 representing the constant differential pressure control mode, The mode shifts to constant differential pressure control mode, and the pressure of the filtrate introduced into the filtrate chamber 1a and the filtrate drawn out from the filtrate chamber 1b are adjusted to the differential pressure target value represented by the differential pressure target value signal S_7. a flow rate adjusting means 4 for adjusting the flow rate of the liquid to be filtered so as to match the differential pressure value with the pressure of means 10A;
When the control stage storage means 10A stores the first control stage, it supplies the control mode signal S_3 representing the constant flow rate control mode and the flow rate target value signal S_4 representing the flow rate target value F_1 to the flow rate adjusting means 4; It is determined that the differential pressure value represented by the differential pressure signal S_6 from the first control stage setting means 10B which sets the first control stage in the adjusting means 4 and the differential pressure measuring means 9 matches the differential pressure target value P_1. Then, when the control stage changing means 10C causes the control stage storage means 10A to store the second control stage, and the control stage storage means 10A stores the second control stage, a control mode signal representing the constant differential pressure control mode S_3 and a differential pressure target value signal S_7 representing the differential pressure target value P_1 to the flow rate regulating means 4, and a second control stage setting means 10D for setting the second control stage in the regulating means 4 is attached. A liquid filtration device characterized by: