JPS63302910A - Method for washing porous filter - Google Patents

Abstract

PURPOSE:To completely remove the fine particles clogging a porous filter by generating the bubbles of gaseous carbon dioxide on the surface of the filter and in the filter. CONSTITUTION:When filtration is carried out, a liq. contg. fine particles is supplied into the raw liq. storage 2a of a hollow yarn membrane container 2, and the liq. is filtered by a hollow yarn membrane filter 1. When the filter 1 is washed, the container 2 is filled with high-pressure carbonated water, a vacuum pump 19 is then driven to rapidly lower the pressure in the container 2, and a large amt. of the bubbles of gaseous carbon dioxide are generated in the water. The bubbles are also generated on the surface of the filter 1 and in the pores, and the deposited fine particles are released by the growing force of the bubbles. As a result, the fine particles clogging the inside of the filter 1 and which were incapable of being removed by the conventional washing method can be completely removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for cleaning a porous filter clogged with fine particles.

(Prior art) In recent years, in the food industry, pharmaceutical industry, atomic crab industry and other fields, hollow fiber membrane filters are used to remove symbolic particles during processing.
Porous filters such as ceramic filters and sintered metal filters are widely used.

By the way, these porous filters come in various shapes and operate in various ways, but they all uniformly capture and deposit particulates to be treated on the filter surface and inside the filter as time passes. Therefore, the filtration performance gradually decreases, and the resistance when passing through the filter increases, the filtration pressure difference increases, and as a result, the processing flow rate decreases.

Therefore, when a predetermined processing capacity cannot be obtained, the filter is cleaned to restore processing performance.

Conventionally, filters have been washed by backwashing by washing with permeate, fresh water, or gas, or by flowing these fluids in the opposite direction to that during filtration. However, depending on the type of particulates trapped and deposited on the filter surface and inside the filter,
Conventional cleaning methods sometimes did not sufficiently restore processing performance. In such cases, cleaning with a chemical solution selected according to the type of particulates would restore treatment performance in most cases, but cleaning with a chemical solution may cause alteration or deterioration of the filter material. In addition to this, there was a problem in that it was necessary to dispose of waste liquid generated by cleaning.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and its purpose is to efficiently remove particulates clogging the filter surface and inside the filter, and to treat waste liquid generated by cleaning. An object of the present invention is to provide a method for cleaning a porous filter that does not require an additional processing device.

[Structure of the Invention] (Means and Effects for Solving the Problems) In order to achieve the above object, the method for cleaning a porous filter of the first invention of the present application involves dissolving carbon dioxide gas in advance under high pressure. A porous filter is immersed in high-pressure carbonated water, and during this immersion, the high-pressure carbonated water is reduced to normal pressure or lower to generate carbon dioxide gas bubbles on the filter surface and inside the filter,
This method is characterized in that the generation of bubbles removes fine particles clogging the porous filter.

Furthermore, in the method for cleaning a porous filter according to the second invention of the present application, high-pressure carbonated water in which carbon dioxide gas has been dissolved in advance at high pressure is passed through the porous filter in the opposite direction to the filtration process. Reducing the pressure inside the porous filter storage container to normal pressure or lower to generate carbon dioxide gas bubbles on the filter surface and inside the filter, and removing particulates clogging the porous filter due to the generation of these bubbles. It is characterized by:

Therefore, according to the porous filter cleaning method of the present invention, by rapidly reducing the pressure of high-pressure carbonated water, a large amount of carbon dioxide bubbles are generated in water, and the growth force of these bubbles and the shear when they rise are The force can peel off and remove fine particles attached to the surface or inside of the porous filter.

(Example) Embodiments of the present invention will be described with reference to the drawings.

The figure is a system diagram of an embodiment of the present invention. In the same figure,
The hollow fiber membrane filter 1 is fixed in a hollow fiber membrane storage container 2 consisting of a stock solution reservoir 2a and a filtrate reservoir 2b. A liquid supply pipe 12 equipped with a valve 5, a concentrated liquid discharge pipe 17 equipped with a valve 7, and a scrubbing air pipe 15 equipped with a valve 10 are connected to the lower part of the stock solution reservoir 2a of the hollow fiber membrane storage container 2. In addition, an overflow pipe 16 equipped with a valve 8 and a vacuum pump 19 are installed above the stock solution reservoir 28 . Valve 21. Piping 2
An exhaust system consisting of 0 is connected.

On the other hand, the filtrate reservoir 2b, which is separated from the stock solution reservoir 2a by a seal (not shown) of the hollow fiber membrane storage container 2, includes a filtrate discharge piping 13 equipped with a valve 6, an air pressurization piping 14 equipped with a valve 9, and a high pressure Carbonated water storage tank 3. Valve 11. Distribution! A high-pressure carbonated water supply system consisting of 18 units is connected. In addition, in order to measure the filtration differential pressure of the hollow fiber membrane filter 1, a liquid supply pipe 12,
A differential pressure gauge 4 is installed between the filtrate discharge pipes 13.

In the filtration process using the hollow fiber membrane filter 1, a liquid containing fine particles is supplied through the liquid supply pipe 12 to the stock solution reservoir 2a of the hollow fiber membrane storage container 2, which is filled with liquid in advance, and is filtered by the hollow fiber membrane filter 1. The filtered filtrate is discharged through the filtrate reservoir 2b and the filtrate discharge pipe 13.

At this time, fine particles in the supplied liquid are captured on the filter surface or inside the filter pores, so as the filtration time passes, the resistance when passing through the filter increases and the filtration differential pressure increases, so the processing flow rate decreases. begins to decline. When such a state occurs, in this embodiment, the supply of processing liquid to the hollow fiber membrane filter 1 is stopped, and the hollow fiber membrane filter 1 is processed by the cleaning method described later, thereby recovering the processing capacity. ing.

By the way, in a normal backwash operation, by pressurizing the filtrate reservoir 2b of the hollow fiber membrane storage container 2 from the air pressure piping 14, the filtrate in the filtrate reservoir 2b is moved in the opposite direction to that during filtration. The liquid is passed through the hollow fiber membrane filter 1, and a large number of bubbles are ejected from the scrubbing air pipe 15 into the stock solution reservoir 2a of the hollow fiber membrane storage container 2 to stir and vibrate the liquid in the stock solution reservoir 2a. Although this method attempts to remove particulates adhering to the membrane surface, it has not been possible to sufficiently remove these particulates depending on the type of particulates trapped and deposited on the filter surface and inside the filter.

Next, a filter cleaning method according to this embodiment will be explained.

Stop the liquid supply to the hollow fiber membrane filter 1, and first close the valves 5, 6,
Close valves 9, 10 and 11, open valves 7 and 8, and remove the stock solution reservoir 2b.
After the valves 7 and 8 are closed, the pressure inside the hollow fiber membrane storage container 2 is increased to the same level as the inside of the high-pressure carbonated water storage tank 3 using a pressure line (not shown). niben 11
is opened, and 2 bp of high-pressure carbonated water is injected from the high-pressure carbonated water storage tank 3 through the valve 11 and piping 18 into the filtrate reservoir of the hollow fiber membrane storage container 2. At this time, while being careful not to reduce the pressure inside the hollow fiber membrane storage container 2, open the valve 8 slightly, fill the inside of the hollow fiber membrane storage container 2 with high-pressure carbonated water, and then close the valves 8 and 11. 1st, drive the vacuum pump 19 and open the valve 21;
At this time, the pressure inside the hollow fiber membrane storage container 2 drops rapidly, and the carbon dioxide gas dissolved in the water at high pressure is dissipated, generating a large amount of bubbles in the water. These bubbles also occur on the surface of the hollow fiber membrane filter 1 and inside the pores,
The generated carbon dioxide gas, which peels off the adhered fine particles due to the growth force of the bubbles, is sucked by the vacuum pump 19.

When the generation of carbon dioxide gas bubbles has finished within the hollow fiber membrane storage container 2, the valve 21 is closed, the vacuum pump 19 is stopped, and then the valve 7 is closed.
, 8 to drain the liquid inside the hollow fiber membrane storage container 2.

In addition, if the valves 11 and 8 are opened after the vacuum pump 19 is stopped and the high-pressure carbonated water is allowed to pass through the hollow fiber membrane filter 1 in the opposite direction to that during filtration, the pressure of the carbonated water decreases and the water permeates. Since carbon dioxide gas bubbles are generated inside, the cleaning effect is further enhanced.

In this example, a hollow fiber membrane filter was used as the porous filter, but a ceramic filter was used instead.

It can be implemented in exactly the same way for other porous filters, such as sintered metal filters.

〔Effect of the invention〕

As explained above, according to the cleaning method of the present invention, a large amount of carbon dioxide gas bubbles are generated in water by rapidly reducing the pressure of high-pressure carbonated water, and the growth force of these bubbles and the shear when they rise are This is because the force is used to peel off and remove fine particles attached to the surface or inside of the porous filter.

It is also possible to completely remove particulates clogging the inside of the filter, which could not be removed using conventional cleaning methods.

In addition, the high-pressure carbonated water used is depressurized by a vacuum pump, and all dissolved carbon dioxide gas is dissipated, leaving only water. This has an excellent effect in that it does not require any additional processing.

[Brief explanation of the drawing]

The figure is a system diagram of an embodiment of the present invention. 1... Hollow fiber membrane filter 2... Hollow fiber membrane storage container 2a... Stock solution reservoir 2b.
...Filtrate reservoir 3...High pressure carbonated water storage tank 4...
・Differential pressure gauge 5, 6, 7, 8, 9.10, 11,
21--Valve 12.13, 14, 15, 16, 17, 1
8.20...Piping 19...Vacuum pump

Claims (2)

[Claims] (1) A porous filter is immersed in high-pressure carbonated water in which carbon dioxide gas has been dissolved at high pressure, and during this immersion, the high-pressure carbonated water is reduced to normal pressure or lower, so that the filter surface and inside the filter are A method for cleaning a porous filter, which comprises generating carbon dioxide gas bubbles and removing particulates clogging the porous filter by the generation of the bubbles. (2) High-pressure carbonated water in which carbon dioxide gas has been dissolved in advance at high pressure,
Pass through the porous filter in the opposite direction to the filtration process,
At this time, the pressure inside the porous filter storage container is reduced to normal pressure or lower to generate carbon dioxide gas bubbles on the filter surface and inside the filter, and the generation of these bubbles removes the particulates clogging the porous filter. A method of cleaning a porous filter, the method comprising: removing the porous filter;