JPS6283004A - Back washing process of filtration device - Google Patents

Abstract

PURPOSE:To eliminate the necessity of back wash tank and back wash pump by back-washing the semi-permeable membrane of the module, which is one of a number of lines and is not filtrating at the moment, with the filtrate coming from some other line, effecting the automatic adjustment of pressure fluctuation and maintaining the pressure at the inlet of module constant. CONSTITUTION:The semi-permeable membrane modules 1,1' and 2,2' are divided into the lines more than one. With the automatic valves 8, 9 and 14 open and the automatic valves 10, 12, 13 and 16 closed, filtration is carried out by the module 1,1' only of the module rack A, and the filtrate is flowed reverse to the normal flow, i.e. from the filtrate supply tube 61 and 62 to the module 2,2' of module rack B to clean the clogging substance in the semi-permeable membrane. The filtrate used for cleaning is sent back to the circulating tank 4 through the second by-pass line 15 and the first by-pass line 11. After finishing the back wash of module rack B, the role of rack A is switched over to the rack B. At this time, the pressure rise at the inlet of module which stops circulating is checked with the censor 23, and the number of rotation of supplying pump 3 is lowered with the control unit to maintain the pressure at the inlet constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for completely cleaning a filtration membrane in order to restore the filtration capacity of a filtration device or completely prevent a decrease in the filtration capacity.

[Conventional technology]

In a semipermeable membrane filtration device with a pore size of 0.2 μm or less, NaCl0 is added to the semipermeable membrane for the purpose of restoring the filtration ability.
, cleaning using chemicals such as NaOH, or cleaning by using a backwashing pump to flow from the Pi side of the F liquid or water-metal semipermeable membrane to the raw solution side in the opposite direction to that during filtration. There are several methods of backwashing, such as filtration and backwashing, and among these backwashing methods, in the case of the above-mentioned method that does not use chemical sounds, it is possible to repeat filtration and backwashing or alternately.

[Problem that the invention seeks to solve]

F'/F of the conventional semipermeable membrane for Pi and water mentioned above! In the method of washing by flowing out from the L side to the stock solution side in the opposite direction to that during filtration, it is necessary to install a backwash pump and a tank for backwashing.Furthermore, if the P solution side comes into contact with outside air, the Pi If there is a risk of an increase in particulate matter, the sealed backwashing tank must be fully used, and the backwashing pump, etc., must be used, so there are equipment problems in order to stabilize the quality of the stock solution. there were.

[Means for solving problems]

As a result of intensive research into a method for backwashing a semipermeable membrane without increasing the amount of fine particles in the stock solution, the inventor has devised a method for backwashing a filtration device that does not require a backwash tank or backwash pump. I found it. That is, the present invention provides a filtration device in which a large number of semipermeable membrane modules are divided into a plurality of series, in which filtration is performed by one or several series of modules among the plurality of series, and the undiluted solution obtained by the filtration is is caused to flow from the raw solution side of a module in a series in which filtration is completely stopped among the plurality of series to backwash the semipermeable membrane of the module, and when the semipermeable membrane is backwashed, or
The feature is that the pressure fluctuation at the time of switching is automatically adjusted to maintain the semipermeable membrane module inlet pressure at a constant level.

[Function] According to the backwashing method of the present invention, the stock solution for backwashing does not come into contact with outside air, and the backwashing pump does not come into contact with the outside air.

Since there is no need for backwashing or backwashing piping, the number of undiluted solutions is reduced, and the amount of fine particles in the undiluted solution does not increase.

In addition, since the pressure on the raw solution inlet side of the semipermeable membrane module in the series that performs the filtration action during backwashing is adjusted to be suppressed from increasing, it is possible to completely prevent the semipermeable membrane from breaking due to pressure.

〔Example〕

Embodiments of the present invention will be described based on flow sheets shown in the figures.

Semipermeable membrane module of 0.2 μm or less 1.1', 2゜2'
,... into a plurality of series, and the modules 1゜1',
. . . The entire series was designated as module rack A, and the module 2.2' was designated as module rack B. . . . The entire series was designated as module rack B. In this embodiment, the number of bases is two, but the number of bases may be greater than this number.

3 is a supply pump that supplies all of the stock solution stored in the stock solution circulation tank 4 to the module racks A and B; 5 is a supply pipe that supplies all of the stock solution from the supply pump 3 to the module racks A and B; 5' Hamojiur rack A
5" is a supply pipe to the module rack B. 6 is a supply pipe for each module 1.1', . . . of the module rack A.
- Deliver the p liquid kFK filtered by F to the point of use.
a liquid supply pipe 6 and each module 2.2' of said module rack B.

- Pri delivers the filtered solution to the point of use.
, a collecting pipe for the stock solution sent by the supply pipe 6□,
Reference numeral 7 is a return pipe for returning E excess residue g and total stock solution circulation tank 4, and 7' and 7'' are outlet pipes leading from module racks A and B to return pipe 7, respectively.

8 is an automatic valve disposed at the inlet of the supply pipe 5' to the module rack A, 9 is an automatic valve disposed at the outlet pipe 7' from the module rack A, and 10 is an automatic valve disposed at the inlet of the supply pipe 5' to the module rack A. An automatic valve installed in the first bypass pipe 11 that connects to the circulation tank 4 branched from the supply pipe 5' between the automatic valve 8 installed at the inlet of the supply pipe 5' and the inlet of the module rack A. be. Further, 12 is an automatic valve disposed at the inlet of the supply pipe 5'' to the module rack B.

13 is an automatic valve installed in the outlet pipe 7'' from module rack B, and 14 is a supply pipe 5 to module rack B.
An automatic valve disposed in a second bypass pipe 15 which is branched through the supply pipe 5 between the automatic valve 12 disposed at the inlet and the inlet of the module rack B and connected to the first bypass pipe 11. 1.17 is an automatic valve disposed in the F liquid collecting pipe 6.

Further, 17 is a pressure regulating valve installed in the supply piping 5 to adjust the pressure of the stock solution supplied to the module racks A and B, and 18 is a pressure regulating valve for adjusting the pressure of the stock solution coming out from the module racks A and B. This is a pressure regulating valve disposed in the return pipe 7. In addition, 19 and 20 are pressure gauges installed in the supply pipe 5' and outlet pipe 7' to measure the pressure at the inlet and outlet of module rack A, and 21 and 22 are pressure gauges for measuring the pressure at the inlet and outlet of module rack B. A pressure gauge is provided on the supply pipe 5" and the outlet pipe 7" for measurement, and 23 is a sensor provided on the inlet side of the module rack to detect the pressure on the inlet side. The inverter of the control unit 24 controls the frequency to change the frequency of the circulation supply pump 3 to control the rotation speed and control the pressure at the module rack inlet.

Since this embodiment is configured as described above, in the case of normal filtration, the automatic valve 8. Automatic valve provided at the outlet of module rack A9. Automatic valve 12 installed in the supply pipe 5'' to module rack B. Automatic valve 13 installed at the outlet of module rack B and automatic valve 1 installed in the F liquid collecting pipe 6.
6 fully open, the first bypass pipe 11 and the second bypass pipe 1
The automatic valves 10 and 14 disposed in each tank 5 are closed, and the stock solution in the circulation tank 4 is supplied to the supply pipe 5 by the supply pump 3.
．． 5', 5', each module 1.1', . . . in module rack A and B system with all valves open.

2.2', . Alternatively, the lachrymal fluid supply pipe 6□ leads to the collecting pipe 6 and is supplied to the Pi usage area. Further, the remaining stock solution is returned to the return pipe 7 through the outlet pipes 7' and 7'', and is returned to the circulation tank 4 through the return pipe γ. It is adjusted by 18.

When the filtration capacity of the semipermeable membrane module decreases due to the progress of the above-mentioned filtration work, the filtration capacity is restored by backwashing.
This backwashing is carried out for several seconds, but when this backwashing is performed, the automatic valve 8 installed at the inlet of the supply pipe 5' to the module rack A, the automatic valve 9 installed at the outlet of the module rack A, and the second bypass pipe 15 are activated. Automatic valve 14 installed is fully open, automatic valve 10 installed in the first bypass pipe. An automatic valve 12 provided at the inlet of the supply pipe 5 to the module rack B, an automatic valve 13 provided at the outlet of the module rack B, and a lacrimal fluid collection tube 6.
When the automatic valve 16'lf installed in the module rack A system is closed, the lachrymal fluid is filtered only by the modules 1.1', . However, since the automatic valve 16 of the collecting pipe 6 is closed, the tear fluid flows into the tear fluid supply pipe 62 of the module rack B, and is filtered by the module rack A series. During normal filtration, the clogging material inside the semipermeable membrane flows from the outside to the inside of the semipermeable membrane of modules 2゜2', ... of the IT module rack B system. Complete cleaning. At this time, as mentioned above, the automatic valve 1 installed at the outlet of module rack B
3 is closed, and the automatic valve 14 disposed in the second bypass pipe 15 branched from the middle of the supply pipe 5'' to module rack B is open, so that each module 2.3 of module rack B is closed. The tear fluid for backwashing that has flowed from the outside to the inside of the semipermeable membranes 2', . Obstruction at thread entrance? The lachrymal fluid that has been removed and used for the above-mentioned backwashing enters the first binoculars tube 11 from the second bypass tube 15 and is returned to the circulation tank 4.

After the backwashing of module rack B is completed as described above, the automatic valve 10 installed in the first bypass pipe, the automatic valve 12 installed in the supply pipe 5'' to module rack B, and the outlet of module rack B The installed automatic valve 13 is fully opened, the automatic valve 8 installed in the supply pipe 5' to module rack A, the automatic valve 9 installed at the outlet of module rack A, and the automatic valve 14 installed in the second bypass pipe. and the automatic valve 16 installed in the lachrymal fluid collection tube 6 is completely closed, and each module 2.2' of the module rack B system is completely filtered.
-g! When the lachrymal fluid is supplied from the L'CP liquid supply tube 6□, since the collecting tube 16 is closed, the lachrymal fluid flows into the lacrimal fluid supply tube 6I of the module rack A, and then flows into the module rank A module 1.1', It flows from the outside to the inside of the semipermeable membrane, in the opposite direction to the normal flow, and washes away all of the clogging material on the inside of the semipermeable membrane.

The tear fluid used for this backwashing flows in the opposite direction to the flow during normal filtration, removes all obstructions at the hollow fiber inlet, and is returned to the circulation tank 4 through the first bypass pipe 11.

In addition, when switching from the normal filtration process to the backwashing process mentioned above, or during backwashing, the circulation of one module rack is stopped and the pressure at the module inlet increases. 23, and the detection signal causes the inno(
- Reduce the evening frequency and reduce the feed pump 30 rpm to keep the module inlet pressure constant. Normally, the filtration and backwashing times are set using a timer, and the module racks on the filtration side and the module racks to be backwashed are alternately switched using automatic switching valves so that all modules are backwashed. Then, after all the modules have been backwashed and the set time has passed, each automatic valve is fully set to return to the normal filtration work described above.

〔Effect of the invention〕

In the method for backwashing a filtration device according to the present invention, a large number of semipermeable membrane modules are arranged in a plurality of series, and one or several series of modules among the plurality of series perform all the filtration.

Since the lachrymal fluid is backwashed by flowing into the lachrymal side of the module in the series where other filtration is stopped, a backwashing pump and a backwashing tank are not required, and the outside air is It is possible to backwash with tear fluid that you do not want to touch, and the use of backwashing to maintain the full filtration capacity of the semipermeable membrane has expanded. In addition, when backwashing a semipermeable membrane module or switching from normal filtration to backwashing process, the pressure on the module inlet side increases, but the pressure fluctuations are automatically adjusted and the pressure on the module inlet side increases. Since it is kept constant at all times, breakage of the semipermeable membrane can be prevented.

[Brief explanation of drawings]

The drawing shows a flow sheet of the method for backwashing a filtration device of the present invention. A, B: Module rack 1, 1', 2.2': Semi-permeable membrane module 3; Supply pump 4 Two circulation tanks 5.5', 5": Supply piping 6 Two Fg collecting pipes 7: Return pipe 8.9 .10.12, 13.14, 16: Automatic valve 17.
18: Pressure regulating valve

Claims (2)

[Claims] (1) In a filtration device in which a large number of semipermeable membrane modules are arranged in a plurality of series, filtration is performed by one or several series of modules among the plurality of series, and the filtrate obtained by the filtration is The semi-permeable membrane of the module is backwashed by flowing from the filtrate side of the module in the series where filtration is stopped, and pressure fluctuations at the time of backwashing or switching of the semipermeable membrane are automatically controlled. A method for backwashing a filtration device, characterized by adjusting and maintaining a constant pressure at the inlet of a semipermeable membrane module. (2) During backwashing, the flow direction on the raw solution side of the semipermeable membrane is reversed to the flow direction during normal filtration, thereby cleaning the semipermeable membrane module inlet side. Method for backwashing a filtration device as described in section.