JP5990431B2 - Filtration apparatus and filtration method - Google Patents

Description

  The technology of the present disclosure relates to a filtering device including a filtering medium that removes foreign matters contained in a mixed solution from the mixed solution, and a filtering method.

  The filtration device connected to the drainage passage of the machine tool removes foreign matters such as chips from the machining fluid discharged from the machine tool. At this time, if the filtration of the processing liquid is excessively repeated, the filter medium provided in the filtration device will be clogged. Therefore, so-called backwashing has been proposed in which a cleaning liquid is flowed in a direction opposite to the direction in which the filtrate flows to remove foreign matter trapped in the filter medium from the filter medium (see, for example, Patent Document 1).

JP 2001-212408 A

  By the way, when the above-described backwashing is necessary, usually many foreign substances are already trapped in the filter medium. In this state, since the flow of the cleaning liquid itself is suppressed by the filter medium, the amount of foreign matter removed by backwashing is limited. As a result, there is still room for improvement in the measure in which the cleaning liquid is simply flowed in the opposite direction in order to suppress clogging of the filter medium.

  An object of the technology of the present disclosure is to provide a filtration device and a filtration method capable of suppressing clogging of a filter medium.

  One aspect of the filtration device according to the present disclosure includes a filter medium having an outflow surface through which a filtrate flows out, a passage communicating with the outflow surface of the filter medium, and a pressure wave on the outflow surface by supplying compressed gas into the passage. And a pressure wave application unit for applying.

  One aspect of the filtration method in the present disclosure is that a mixed liquid is put into an inflow surface of a filter medium and the filtrate is discharged from the outflow surface of the filter medium, and a compressed gas is supplied into a passage communicating with the outflow surface, and the pressure by the supply Applying waves to the outflow surface.

  According to the technique in the present disclosure, a pressure wave due to the supply of compressed gas is applied to the outflow surface from which the filtrate flows out, so that foreign matter trapped in the filter medium is pushed out of the filter medium by the pressure wave. Therefore, clogging of the filter medium can be suppressed as compared with a mode in which the cleaning liquid is simply flowed in the opposite direction.

It is a flow-path system figure which shows the structure of the flow path in the filtration apparatus of one Embodiment with which the technique of this indication was actualized. It is a fragmentary sectional view which shows a part of internal structure of the filtration tank with which a filtration apparatus is provided. It is a block diagram which shows functionally the structure of the control apparatus with which a filtration apparatus is provided. It is a figure which shows the state of the drive of the valve in each mode in a backwash process. It is a flow-path system figure which shows the drive state of the valve in a filtration process. It is a figure which shows the state of the drive of the valve in the stop process in a backwash process. It is a figure which shows the state of the drive of the valve in the preparatory process of a 1st mode. It is a figure which shows the drive state of the valve in the backwashing process in a backwashing process. The action figure which shows the effect | action of the pressure wave which generate | occur | produces in a backwash process. The action figure which shows the effect | action of the pressure wave which generate | occur | produces in a backwash process. It is a figure which shows the state of the drive of the valve in the preparatory process of a 2nd mode. It is a figure which shows the drive state of each valve in the preparatory process of a 3rd mode.

An embodiment embodying the technology of the present disclosure will be described with reference to FIGS. 1 to 12.
As shown in FIG. 1, in the filtration device 10, the inlet end Lmi in the mixed liquid passage Lm is connected to the supply source of the mixed liquid, and the outlet end Lmo in the mixed liquid passage Lm is the discharge destination of the mixed liquid. Connected to. The mixed liquid is a liquid to be filtered, for example, a liquid in which foreign matters such as chips are mixed in water. The supply source of the mixed liquid is, for example, a mixed liquid storage tank mounted on a machine tool.

  In the middle of the mixed liquid passage Lm, a mixed liquid supply valve Vsm and a mixed liquid discharge valve Vdm are provided in this order from the inlet end Lmi. Each of the mixed liquid supply valve Vsm and the mixed liquid discharge valve Vdm switches between communication of the mixed liquid passage Lm and blocking of the mixed liquid passage Lm. Each of the liquid mixture supply valve Vsm and the liquid mixture discharge valve Vdm employs a drive system in which rapid opening and rapid closing are performed, and for example, an air pressure operation type is used.

  In the filtration device 10, the inlet end Lfi in the filtrate passage Lf is connected to a supply source of compressed air, and the outlet end Lfo in the filtrate passage Lf is connected to a filtrate discharge destination. In the middle of the filtrate passage Lf, a compressed air tank 11, a check valve VR, an air supply valve Vsa, and a filtrate discharge valve Vdf are provided in this order from the inlet end Lfi.

The compressed air tank 11 is supplied with compressed air as compressed gas from the facility. The internal pressure in the compressed air tank 11 is maintained at, for example, 0.2 kg / cm ² by steady supply of compressed air. The check valve VR allows the flow of compressed air from the compressed air tank 11 to the air supply valve Vsa, and restricts the flow of filtrate from the air supply valve Vsa to the compressed air tank 11. Each of the air supply valve Vsa and the filtrate discharge valve Vdf switches between communication of the filtrate passage Lf and blocking of the filtrate passage Lf. Each of the air supply valve Vsa and the filtrate discharge valve Vdf employs a driving system in which rapid opening and rapid closing are performed, and for example, an air pressure operation type is used.

  In the mixed liquid passage Lm, a filter 21 is connected between the mixed liquid supply valve Vsm and the mixed liquid discharge valve Vdm. The filter 21 has a cylindrical shape having two cylindrical end portions facing each other. The capacity of the filter 21 is substantially the same as the capacity of the compressed air tank 11, for example.

  The mixing-side end portion 21m of the filter 21 is connected between the mixed solution supply valve Vsm and the mixed solution discharge valve Vdm in the mixed solution passage Lm, and the filtrate side end portion 21f of the filtering device 21 is connected to the filtrate passage Lf. Among these, it is connected between the air supply valve Vsa and the filtrate discharge valve Vdf. A portion of the filtrate passage Lf between the air supply valve Vsa and the filtrate discharge valve Vdf is disposed above the filter 21 and has a passage extending upward with respect to the filter 21.

  In order to suppress the pressure loss of the mixed solution and the pressure loss of the filtrate, the mixing side end portion 21m and the mixed solution passage Lm are connected by two passages, and both the filtrate side end portion 21f and the filtrate passage Lf are It is connected by two passages.

  A backwash tank 31 is connected between the mixed liquid discharge valve Vdm and the outlet end Lmo in the mixed liquid passage Lm. The backwash tank 31 has a cylindrical shape having two cylinder ends facing each other, and one cylinder end in the backwash tank 31 is connected to the mixed liquid passage Lm, and another cylinder in the backwash tank 31 is formed. The end is connected to a decompression passage Lp opened to the outside.

Next, the configuration of the filter 21 will be described with reference to FIG.
The filtration tank 22 constituting the filter 21 has a cylindrical shape having two cylinder ends, and the cylinder of the filtration tank 22 communicates with the mixed liquid passage Lm and the filtrate passage Lf. The filtration tank 22 is composed of two cylindrical portions having the same axis. Each of the first cylindrical portion 22m and the second cylindrical portion 22f, which are two cylindrical portions, has a cylindrical shape having two cylindrical end portions facing each other.

  One cylinder end portion in the first cylindrical portion 22m is a mixing side end portion 21m in the filter 21, and the inside of the first cylindrical portion 22m communicates with the mixed liquid passage Lm. Another cylindrical end portion of the first cylindrical portion 22m is a connecting end portion connected to the second cylindrical portion 22f, and has a first flange portion FA that protrudes toward the central axis of the first cylindrical portion 22m. One cylinder end portion in the second cylindrical portion 22f is a filtrate side end portion 21f in the filter 21, and the inside of the second cylindrical portion 22f communicates with the filtrate passage Lf. The other cylindrical end portion of the second cylindrical portion 22f is a connecting end portion that is connected to the first cylindrical portion 22m, and has a second flange portion FB that protrudes toward the central axis of the second cylindrical portion 22f.

  The outer diameter of the first cylindrical portion 22m and the outer diameter of the second cylindrical portion 22f are substantially equal, and the inner diameter of the first flange portion FA is larger than the inner diameter of the second flange portion FB. The first flange portion FA and the second flange portion FB communicate with each other in the cylinder of the first cylindrical portion 22m and the cylinder of the second cylindrical portion 22f, and the first flange portion FA and the second flange portion. In order to prevent liquid from leaking between the FB and the FB, for example, they are connected via a seal member.

  A pedestal 23 is disposed at the mixing side end portion 21m of the first cylindrical portion 22m. The pedestal 23 has a columnar shape having an outer diameter smaller than the inner diameter of the first cylindrical portion 22m and having the same axis as the first cylindrical portion 22m. A filter medium 25 is disposed on the pedestal 23 inside the first cylindrical portion 22m. The filter medium 25 has a cylindrical shape having the same axial center as that of the first cylindrical portion 22m, and the outer diameter of the filter medium 25 is substantially equal to the outer diameter of the pedestal 23 and is substantially equal to the inner diameter of the first flange portion FA. A seal member is sandwiched between the filter medium 25 and the pedestal 23 and between the filter medium 25 and the second flange portion FB so that liquid does not leak from the filter medium 25 and the second flange portion FB.

  The mixed liquid flowing into the first cylindrical portion 22m from the mixed liquid passage Lm passes through the gap between the inner peripheral surface of the first cylindrical portion 22m and the outer peripheral surface 251 of the filter medium 25 from the outer peripheral surface 251 of the filter medium 25. It flows toward the inner peripheral surface 252 of 25. That is, the outer peripheral surface 251 of the filter medium 25 functions as an inflow surface of the mixed liquid, and the inner peripheral surface 252 of the filter medium 25 functions as an outflow surface of the filtrate. At this time, foreign substances contained in the mixed liquid are trapped by the outer peripheral surface 251 of the filter medium 25, and the filtrate, which is the mixed liquid from which foreign substances have been removed, enters the second cylindrical portion 22 f from the inside of the filter medium 25.

  Further, the filtrate flowing into the second cylindrical portion 22f from the filtrate passage Lf is directed from the inner peripheral surface 252 of the filter medium 25 to the outer peripheral surface 251 of the filter medium 25 through the inside of the second cylindrical portion 22f and the inside of the filter medium 25. Flowing. At this time, the foreign matter trapped on the outer peripheral surface 251 of the filter medium 25 is pushed out of the filter medium 25 by the filtrate. And the filtrate containing the foreign material extruded from the filter medium 25 flows to the exterior of the 1st cylindrical part 22m through the clearance gap between the internal peripheral surface of the 1st cylindrical part 22m, and the outer peripheral surface 251 of the filter medium 25. FIG.

  A dispersion member 26 having a truncated cone shape is fixed to the pedestal 23 in the cylinder of the filter medium 25. The dispersion member 26 is made of a material having corrosion resistance to the filtrate and non-solubility to the filtrate. The outer diameter of the dispersion member 26 is smaller than the inner diameter of the filter medium 25, and gradually increases from the pedestal 23 toward the second flange portion FB between the outer peripheral surface of the dispersion member 26 and the inner peripheral surface 252 of the filter medium 25. There is a gap. In the direction along the central axis of the filter medium 25, the length of the dispersion member 26 is, for example, not less than half the length of the filter medium 25 and not more than 2/3 of the length of the filter medium 25. Then, the pressure wave propagating from the second cylindrical portion 22 f into the cylinder of the filter medium 25 is dispersed with respect to the inner peripheral surface 252 of the filter medium 25 through the collision with the dispersion member 26. The pressure wave is a discontinuous wave front of pressure propagating in the liquid inside the filter medium 25.

Next, the electrical configuration of the filtration device 10 will be described with reference to FIG.
As shown in FIG. 3, the process setting unit 41 configuring the filtration device 10 is connected to an external input device, and inputs various processing conditions in the filtration device 10 from the input device. In the process setting unit 41, for example, the filtration process time, which is an accumulated value of the time during which the filtration process is performed, is set as a switching condition for switching the process content in the filtration device 10 between the filtration process and the backwash process. And the process setting part 41 measures filtration process time, and when the measured value of filtration process time is below a switching condition, sets the filtration process as a process which the filtration apparatus 10 performs. Moreover, the process setting part 41 sets a backwash process as a process which the filtration apparatus 10 performs, and resets the filtration process time, when the measured value of the filtration process time is larger than switching conditions.

  The filtration control unit 42 reads the setting process in the process setting unit 41 at a predetermined control cycle. Further, the filtration control unit 42 stands by until the setting process in the process setting unit 41 becomes a filtration process. And whenever the setting process in the process setting part 41 transfers to a filtration process, the filtration control part 42 closes the liquid mixture discharge valve Vdm and the air supply valve Vsa, and also supplies the liquid mixture supply valve Vsm and the filtrate discharge valve. A control signal for opening Vdf is output to the valve drive unit 45.

  The backwash mode setting unit 43 is connected to an external input device, and inputs the mode of backwash processing in the filtration device 10 from the input device. The backwash mode setting unit 43 sets any one of the first mode, the second mode, and the third mode as the mode of the backwash process.

  The backwash control unit 44 reads the setting process in the process setting unit 41 at a predetermined control cycle. In the backwash control unit 44, the driving states of the valves Vsm, Vdm, Vsa, and Vdf are associated with each backwash process mode. Further, the backwash control unit 44 waits until the setting process in the process setting unit 41 becomes the backwash process. And whenever the setting process in the process setting part 41 transfers to a backwash process, the backwash control part 44 reads the setting mode in the backwash mode setting part 43. FIG. Further, the backwash control unit 44 generates a control signal for controlling the drive state of each valve Vsm, Vdm, Vsa, Vdf based on the read setting mode and outputs the control signal to the valve drive unit 45.

  The valve drive unit 45 generates a drive signal for driving each valve Vsm, Vdm, Vsa, Vdf in accordance with a control signal from the filtration control unit 42, and generates the generated drive signal for each valve Vsm, Vdm, Output to Vsa and Vdf.

Next, the driving state of each valve in the backwash process will be described for each mode with reference to FIG.
As shown in FIG. 4, the backwash control unit 44 drives each valve Vsm, Vdm, Vsa, Vdf for each process in each mode of the backwash process, and the time for which the process is executed. Are set, and the number of times the preparation process and the backwashing process are repeated is set.

  In the first mode, the stop process, the preparation process, and the backwash process are set in this order, and the number of times that the preparation process and the backwash process are alternately repeated is set as the set number N1. The stop process is set as a state in which only the filtrate discharge valve Vdf is open. The time for which the stop process is executed is set to time Tp1. In the preparation process, all the valves Vsm, Vdm, Vsa, and Vdf are closed. The time during which the preparation process is executed is set to time Ts1. The backwashing process is set as a state where the air supply valve Vsa and the mixed liquid discharge valve Vdm are opened. The time for performing the backwashing process is set to time Tr1.

  In the second mode, the stop process, the preparation process, and the backwashing process are set in this order, and the number of times that the preparation process and the backwashing process are alternately repeated is set as the set number N2. The stop process is set as a state where only the filtrate discharge valve Vdf is opened, as in the first mode. The time for which the stop process is executed is set as time Tp2. The preparation process is set as a state in which only the mixed liquid discharge valve Vdm is opened. The time during which the preparation process is executed is set to time Ts2. As in the first mode, the backwash process is set such that the air supply valve Vsa and the mixed liquid discharge valve Vdm are open. The time for which the backwash process is executed is set as time Tr2.

  In the third mode, the stop step, the first backwashing step, and the second backwashing step are set in this order, and the number of times the first backwashing step and the second backwashing step are alternately repeated, It is set as the set number N3. The stop process is set as a state where only the filtrate discharge valve Vdf is opened, as in the first mode. The time for which the stop process is executed is set as time Tp3. The first back washing process in the third mode is set as a state where only the air supply valve Vsa is opened. The time for which the first backwashing process is executed is set as time Ts3. The second back washing process in the third mode is set as a state where the air supply valve Vsa and the mixed liquid discharge valve Vdm are opened. The time for which the second back washing process is executed is set as time Tr3.

Next, a filtration method performed by the filtration device 10 will be described with reference to FIGS.
As shown in FIG. 5, when the setting process in the process setting unit 41 shifts from the backwash process to the filtration process, the mixed solution supply valve Vsm and the filtrate discharge valve Vdf open, and the mixed solution discharge valve Vdm and the air The supply valve Vsa is closed.

  That is, the filtration control unit 42 outputs a control signal for closing the mixed solution discharge valve Vdm and the air supply valve Vsa to the valve driving unit 45, and then opens the mixed solution supply valve Vsm and the filtrate discharge valve Vdf. Is output to the valve drive unit 45. The valve drive unit 45 outputs a drive signal for closing the mixed liquid discharge valve Vdm and the air supply valve Vsa to these two valves Vdm and Vsa in response to a control signal from the filtration control unit 42. Next, the valve drive unit 45 outputs a drive signal for opening the mixed solution supply valve Vsm and the filtrate discharge valve Vdf.

  Accordingly, the mixed solution is supplied from the supply source of the mixed solution to the filter 21, and the mixed solution flows from the outer peripheral surface 251 of the filter medium 25 toward the inner peripheral surface 252 of the filter medium 25. Foreign matters contained in the mixed liquid are trapped by the outer peripheral surface 251 of the filter medium 25, and the filtrate, which is the mixed liquid from which foreign substances have been removed, is discharged from the cylinder of the filter medium 25 through the filtrate discharge valve Vdf.

  As shown in FIG. 6, when the setting process in the process setting unit 41 shifts from the filtration process to the backwash process, the backwash control unit 44 determines each valve Vsm based on the setting mode in the backwash mode setting unit 43. , Vdm, Vsa, Vdf, a control signal for controlling the driving state is output to the valve drive unit 45.

  For example, when the setting mode in the backwash mode setting unit 43 is the first mode, the backwash control unit 44 first provides a control signal for opening only the filtrate discharge valve Vdf as the valve driving unit 45 as a stop process. Output to. In response to the control signal from the backwash control unit 44, the valve drive unit 45 outputs a drive signal for opening only the filtrate discharge valve Vdf to the filtrate discharge valve Vdf. Thereby, the pressure inside the filter 21 is reduced from the pressure at the time of filtration to the atmospheric pressure during the time Tp1, and in particular, the pressure inside the second cylindrical portion 22f is reduced to the atmospheric pressure. The

  As shown in FIG. 7, when the stop process ends, the backwash control unit 44 outputs a control signal for closing all the valves Vsm, Vdm, Vsa, Vdf to the valve drive unit 45 as a preparation process. The valve drive unit 45 outputs a drive signal for closing all the valves Vsm, Vdm, Vsa, Vdf to the valves Vsm, Vdm, Vsa, Vdf in response to a control signal from the backwash control unit 44. Thereby, the inside of the filter 21 is left still only for the time Ts1.

  As shown in FIG. 8, when the preparation process is completed, the backwash control unit 44 sends a control signal to the valve drive unit 45 to open the air supply valve Vsa and the mixed liquid discharge valve Vdm at the same time as the backwash process. Output. The valve drive unit 45 outputs a drive signal for opening the air supply valve Vsa and the mixed liquid discharge valve Vdm to the air supply valve Vsa and the mixed liquid discharge valve Vdm in response to a control signal from the backwash control unit 44. To do. As a result, the air supply valve Vsa and the mixed liquid discharge valve Vdm open simultaneously. And when a backwash process is complete | finished, the backwash control part 44 repeats a preparatory process and a backwash process again by the setting frequency | count N1 in this order again. Note that the set number N1 is set such that all of the filtrate in the cylinder of the filter medium 25 is discharged from the filter 21 by repeating the preparation process and the backwashing process.

  At this time, the air supply valve Vsa is a boundary between the filtrate and the compressed air in the filtrate passage Lf. Therefore, when the air supply valve Vsa is suddenly opened, the compressed air stored in the compressed air tank 11 immediately acts on the filtrate filling the filtrate passage Lf to generate a pressure wave. Then, the pressure wave propagated inside the filter 21 disappears outside through the outlet end Lfo of the mixed liquid passage Lm or the backwash tank 31.

  As shown in FIG. 9, the pressure wave propagated inside the filter medium 25 propagates from the inner peripheral surface 252 of the filter medium 25 toward the inner peripheral surface of the first cylindrical portion 22m, and in the process of propagation, the pressure wave propagates to the foreign matter 25R. Works. As a result, most of the energy of the pressure wave is consumed to move the foreign object 25R in the direction in which the pressure wave travels. The foreign matter 25R trapped on the outer peripheral surface 251 of the filter medium 25 is removed from the outer peripheral surface 251 by a part of the energy of the pressure wave.

  As shown in FIG. 10, when the preparation process and the backwashing process are repeated from the state where the foreign matter 25 </ b> R is removed, the pressure wave propagates again inside the filter medium 25. In a state where the foreign matter 25R is not captured by the outer peripheral surface 251, most of the energy of the pressure wave propagates to the gap between the outer peripheral surface 251 of the filter medium 25 and the first cylindrical portion 22m. And the liquid pushed out from the filter 21 for every backwashing process is discharged | emitted from the exit edge part Lmo of the liquid mixture channel | path Lm, and also is discharged | emitted also inside the backwash tank 31. FIG. As a result, a part of the energy of the pressure wave is released into the backwash tank 31, so that the mechanical resistance required for the application of the pressure wave is suppressed in the filter device 10, particularly in the mixed liquid passage Lm. . In addition, since the pressure wave propagated inside the mixed liquid passage Lm is suppressed from being reflected toward the filter 21, the removed foreign matter 25R can be smoothly discharged.

  The pressure wave generated inside the filtrate passage Lf acts on the inside of the filter medium 25 through a passage extending upward from the filter 21. And a pressure wave advances along the direction where the filtrate collected in the inside of the 2nd cylindrical part 22f, or the filtrate collected in the inside of the filter medium 25 acts. Therefore, the energy of the pressure wave acting on the foreign material 25R is increased as compared with the case where the pressure wave travels in a direction opposite to the direction in which the weight of the filtrate acts.

  In addition, a dispersion member 26 that disperses the pressure wave propagating from the second cylindrical portion 22 f into the tube of the filter medium 25 to the inner peripheral surface 252 of the filter medium 25 is disposed inside the filter medium 25. Therefore, the pressure wave propagating into the tube of the filter medium 25 is dispersed with respect to the inner peripheral surface 252 of the filter medium 25 through the collision with the dispersion member 26. As a result, the pressure wave acts on substantially the entire outer peripheral surface 251, and the foreign matter 25 </ b> R is removed from almost the entire outer peripheral surface 251.

  On the other hand, when the pressure wave acts only on a part of the inner peripheral surface 252, the foreign matter 25 </ b> R is removed only on a part of the outer peripheral surface 251. Even if the pressure wave is reapplied by repeating the preparation process and the backwashing process, most of the pressure wave propagated in the cylinder of the filter medium 25 passes through the outer surface of the filter medium 25 through the portion from which the foreign matter 25R has been removed. It will propagate to the gap between 251 and the 2nd cylindrical part 22f. After all, in order to remove the foreign matter 25R over the entire outer peripheral surface 251, it is necessary to increase the set number N1. In this regard, if the dispersion member 26 is disposed inside the filter medium 25, the pressure wave acts on substantially the entire outer peripheral surface 251, so that the set number of times N1 is prevented from increasing.

  When the setting mode in the backwash mode setting unit 43 is the second mode, the backwash control unit 44 first executes a stop process in the second mode, as in the first mode, and the filter The pressure inside 21 is reduced from the pressure at the time of filtration to atmospheric pressure during time Tp2.

  As shown in FIG. 11, when the stop process in the second mode is completed, the backwash control unit 44 outputs a control signal for opening only the mixed liquid discharge valve Vdm to the valve drive unit 45. The valve drive unit 45 outputs a drive signal for opening only the mixed liquid discharge valve Vdm in response to a control signal from the backwash control unit 44. Thereby, the pressure inside the first cylindrical portion 22m, in particular, the pressure in the gap between the outer peripheral surface 251 of the filter medium 25 and the second cylindrical portion 22f is reduced to atmospheric pressure.

  When the preparation process is completed, the backwash control unit 44 outputs a control signal for opening the air supply valve Vsa to the valve drive unit 45 as the backwash process in the second mode. The valve drive unit 45 outputs a drive signal for opening the air supply valve Vsa to the air supply valve Vsa in response to a control signal from the backwash control unit 44. As a result, the air supply valve Vsa and the mixed liquid discharge valve Vdm are opened. And when a backwash process is complete | finished, the backwash control part 44 repeats a preparation process and a backwash process again by the set number of times N2 in this order again.

  At this time, when the air supply valve Vsa is suddenly opened, the compressed air stored in the compressed air tank 11 immediately acts on the inside of the filtrate passage Lf to generate a pressure wave as in the first mode. The pressure wave propagated inside the filter medium 25 propagates from the inner peripheral surface 252 of the filter medium 25 toward the inner peripheral surface of the first cylindrical portion 22m, and acts on the foreign matter 25R in the process of propagation. Here, in the preparatory process in the second mode, the pressure in the gap between the outer peripheral surface 251 of the filter medium 25 and the first cylindrical portion 22m is reduced to atmospheric pressure. Therefore, compared with the case where the pressure in the gap between the outer peripheral surface 251 of the filter medium 25 and the second cylindrical portion 22f is higher than the atmospheric pressure, the foreign matter 25R captured by the outer peripheral surface 251 of the filter medium 25 is separated from the outer peripheral surface 251. It becomes easy to be removed.

  When the setting mode in the backwash mode setting unit 43 is the third mode, the backwash control unit 44 first executes a stop process in the third mode, as in the first mode, and the filter The pressure inside 21 is reduced from the pressure at the time of filtration to atmospheric pressure during time Tp3.

  As shown in FIG. 12, when the stop process in the third mode is completed, the backwash control unit 44 sends a control signal for opening only the air supply valve Vsa as the first backwash process in the third mode. Output to the valve drive unit 45. The valve drive unit 45 outputs a drive signal for opening only the air supply valve Vsa in response to a control signal from the backwash control unit 44. As a result, only the air supply valve Vsa is opened.

  At this time, when the air supply valve Vsa is suddenly opened, the compressed air stored in the compressed air tank 11 immediately acts on the inside of the filtrate passage Lf to generate a pressure wave as in the first mode. The pressure wave propagated inside the filter medium 25 propagates from the inner peripheral surface 252 of the filter medium 25 toward the inner peripheral surface of the first cylindrical portion 22m, and the foreign matter 25R is removed from the outer peripheral surface 251 in the course of the propagation. Further, since the air supply valve Vsa is opened rapidly with the mixed liquid discharge valve Vdm closed, the propagation of the pressure wave is stopped by the mixed liquid discharge valve Vdm. As a result, in the inside of the filter 21, it is possible to suppress the liquid from flowing rapidly and greatly as the pressure wave propagates, compared to the first mode. Therefore, the resistance of the filter medium 25 required for the application of the pressure wave is suppressed.

  Then, when the first backwashing process is completed, the backwashing control unit 44 outputs a control signal for opening the mixed liquid supply valve Vsm to the valve driving unit 45 as the second backwashing process in the third mode. The valve drive unit 45 outputs a drive signal for opening the mixed solution supply valve Vsm to the air supply valve Vsa in response to a control signal from the backwash control unit 44. As a result, the air supply valve Vsa and the mixed liquid discharge valve Vdm are opened. And when a 2nd backwashing process is complete | finished, the backwashing control part 44 repeats a 1st backwashing process and a 2nd backwashing process by the set number of times N3 in this order again.

The above embodiment can be implemented with the following modifications.
The dispersing member 26 may be omitted, or the preparation process may be omitted from each of the first mode and the second mode. Further, the backwash tank 31 may be omitted, or a portion of the filtrate passage Lf between the air supply valve Vsa and the filtrate discharge valve Vdf may be disposed below the filter 21. Further, the shape of the filter medium may be a plate shape or a lump shape, and the liquid mixture supplied to the filter may be a liquid discharged from a pool, a water tank or the like. Further, the compressed gas may be compressed nitrogen or the like. In short, any configuration in which a pressure wave is applied to the outflow surface of the filter medium may be used.

  In the above embodiment, the pressure application unit is configured by the filtrate passage Lf, the compressed air tank 11, the air supply valve Vsa, the filtrate discharge valve Vdf, and the filtration tank 22. However, the compressed air tank 11 may be omitted in the pressure application unit. Further, if the air supply valve Vsa and the filtrate discharge valve Vdf are connected to the filtration tank 22 through separate passages, the air supply valve Vsa, the filtration tank 22, and the air supply valve Vsa and the filtration tank 22 are connected. The pressure application unit may be configured by a passage connecting the two.

The liquid mixture supply valve Vsm and the liquid mixture discharge valve Vdm may be connected to the filtration tank 22 via individual passages.
-In the backwash process which the filtration apparatus 10 performs, two or more modes which are mutually different may be continuous, and only one mode may always be implemented.

In addition, the filtration apparatus in this indication can also be set as the structure of following (1) and (2).
(1) A filter medium having an outflow surface through which the filtrate flows out, a passage communicating with the outflow surface of the filter medium, and a pressure wave applying unit that applies a pressure wave to the outflow surface by supplying compressed gas into the passage. ,
And the passage extends upward relative to the filter medium, and the pressure wave application unit supplies the compressed gas from above the filter medium.

  (2) The pressure application unit is connected to the passage and stores a compressed gas, and a valve is provided in the middle of the passage to switch between communication between the tank and the outflow surface and blocking of the communication. The filtration apparatus as described in said (1) provided with.

  Vdf: filtrate discharge valve, Vdm: mixed solution discharge valve, Vsa: air supply valve, Vsm: mixed solution supply valve, 10: filtration device, 22: filtration tank, 25: filter medium, 251 ... outer peripheral surface, 252 ... inner peripheral surface 26: Dispersing member.

Claims (3)

A filtration tank;
A backwash tank with one end open to the outside;
A filter medium located in the filtration tank and having an inflow surface into which a liquid to be filtered enters, and an outflow surface from which the filtrate flows out;
A passage communicating with the outflow surface of the filter medium;
A pressure wave application unit that applies a pressure wave to the outflow surface by supplying compressed gas into the passage;
A backwash control unit that applies pressure waves to the outflow surface in a state where a passage connecting the backwash tank and the inflow surface is opened, and pushes the liquid in the filtration tank in a direction in which its own weight acts;
A filtration apparatus comprising: The filter medium has a cylindrical shape,
The outflow surface is an inner peripheral surface of the filter medium;
The passage communicates with one cylinder end of both the cylinder ends of the filter medium,
The filtration apparatus according to claim 1, further comprising a dispersion member that disperses the pressure wave with respect to the outflow surface in a cylinder of the filter medium. Putting the mixed liquid into the inflow surface of the filter medium and taking out the filtrate from the outflow surface of the filter medium,
While connecting the inlet flow face to the backwash tank different from the filtration tank where the filter media is housed, the pressure wave due to the supply by supplying the compressed gas into the passage communicating with the outlet flow face, in addition to the outflow surface Pushing out the liquid in the filtration tank in a direction in which its own weight acts ;
A filtration method comprising:

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