JP5985914B2 - Control device for chemical solution circulation in membrane treatment equipment - Google Patents

Description

  The present invention relates to a chemical solution circulation control device of a membrane treatment device, and more specifically, a chemical solution in a circulation tank is supplied to a membrane treatment device via a chemical solution supply pipe by a circulation pump, and the membrane is provided in the membrane treatment device. The present invention relates to a chemical solution circulation control device of a membrane treatment apparatus that cleans the membrane by bringing it into contact with the liquid and returns the cleaned chemical solution to the circulation tank via a chemical solution return pipe.

  A cargo ship that transports crude oil or the like is provided with a ballast tank in order to maintain the stability of the hull during navigation. Usually, when crude oil or the like is not loaded, the inside of the ballast tank is filled with ballast water, and when the crude oil or the like is loaded, the ballast water is discharged to adjust the buoyancy of the hull and stabilize the hull.

  As described above, the ballast water is water necessary for the safe navigation of the ship, and the seawater of the port that performs cargo handling is usually used. The amount is said to exceed 10 billion tons per year worldwide.

  By the way, aquatic organisms inhabiting the port where the water is taken are mixed in the ballast water, and these aquatic organisms are transported to an area where they do not originally exist as the ship moves.

  Therefore, the destruction of ecosystems, such as the replacement of existing species with species that did not originally live in the sea, has become serious.

  Against this background, a convention for the regulation and management of ship ballast water and sediments (hereinafter referred to as the Convention) was adopted at an international conference of the International Maritime Organization (IMO), and a ballast water treatment device was used. The duty to carry out ballast water management is about to be applied to ships built after 2009.

  For this reason, when discharging ballast water, it is necessary to remove or kill up to about 1/100 of the number of organisms present in the open ocean.

  The present applicant has proposed a technique for treating ballast water with a filtration membrane (Patent Document 1).

Japanese Patent No. 4214494

  In the ballast water membrane treatment apparatus, deposits adhere to the membrane along with the membrane filtration treatment. Since this deposit reduces the flux, it must be removed from the film.

  In order to remove the deposits, washing with a chemical solution containing a chemical such as hydrogen peroxide is suitable. Specifically, by supplying the chemical stored in the circulation tank to the membrane processing apparatus, cleaning the membrane provided in the membrane processing apparatus, and using the circulation cleaning that returns the cleaned chemical to the circulation tank, The deposit can be removed from the film to restore the flux.

  However, chemicals such as hydrogen peroxide are decomposed by coming into contact with the deposits on the film, and bubbles are generated in the chemical solution. As a result, the apparent volume of the chemical solution increases, the water level in the circulation tank rises, and there arises a problem that the chemical solution overflows from the circulation tank.

  On the other hand, it is conceivable to increase the capacity of the circulation tank that receives the chemical solution so as to cope with the rise in the water level. However, it is difficult to secure a space for installing a large-capacity circulation tank, and it is not practical to install it in a limited space such as in a ship.

  Accordingly, an object of the present invention is to provide a chemical solution circulation control device of a membrane treatment apparatus capable of reducing the capacity of a circulation tank.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

(Claim 1)
A circulating fluid supply system for supplying the chemical solution in the circulation tank from the circulation tank to the membrane treatment device with a filtration membrane via the chemical solution supply pipe;
A chemical cleaning system for cleaning and removing deposits adhering to the filtration membrane with the chemical,
A circulating liquid return system for returning the chemical liquid after washing to the circulation tank via a chemical liquid return pipe as a circulating liquid;
Forming a circulation system of the chemical liquid that circulates the chemical liquid by the power of the circulation pump through the circulating liquid supply system and the circulating liquid return system,
The circulation tank is provided with an on-off valve that can seal the inside of the tank, and a liquid level gauge that detects the water level of the chemical in the tank is provided, and the following controls (1) and (2) are performed. A control device for chemical solution circulation in a membrane treatment apparatus.
(1) When an increase in the water level of the chemical liquid in the circulation tank is detected by HL (high level) of the liquid level gauge due to an increase in the apparent volume of the chemical liquid containing bubbles generated from the chemical liquid by the cleaning, Control to change the open / close valve from open to closed.
(2) After closing the on-off valve, bubbles are separated from the chemical liquid in the circulation tank, the apparent volume of the chemical liquid is reduced, and the separated bubbles are above the water level of the chemical liquid in the circulation tank. When the water level drop caused by expanding the upper space is detected by LL (low level) of the liquid level gauge, the on / off valve is controlled to be changed from closed to open.

(Claim 2)
2. The chemical solution circulation control device for a film processing apparatus according to claim 1, wherein the chemical solution contains at least hydrogen peroxide.

(Claim 3)
3. The chemical solution circulation control device for a membrane treatment device according to claim 1, wherein the membrane treatment device is a ballast water membrane treatment device mounted on a ship.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the chemical | medical solution circulation of the membrane treatment apparatus which can reduce a capacity | capacitance of a circulation tank can be provided.

Schematic which shows an example of the control apparatus of the chemical | medical solution circulation of the membrane treatment apparatus which concerns on this invention The graph which shows an example of the time-dependent change of the water level of the chemical | medical solution in the circulation tank of this invention The graph which shows the other example of the time-dependent change of the water level of the chemical | medical solution in the circulation tank of this invention

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing an example of a chemical solution circulation control device of a membrane processing apparatus according to the present invention.

  In FIG. 1, 1 is a circulation tank, 2 is a circulation pump, 3 is a chemical solution supply pipe, 4 is a membrane treatment device with a filtration membrane, and 5 is a chemical solution return pipe.

  In this embodiment, there is a circulating liquid supply system 101 that supplies the chemical solution in the circulation tank 1 from the circulation tank 1 through the chemical solution supply pipe 3 to the membrane treatment device 4 with a filtration membrane. Moreover, in this embodiment, the chemical solution cleaning system for cleaning / removing the adhering matter attached to the filtration membrane with the chemical solution is provided. Further, in the present embodiment, there is a circulating liquid return system 102 that returns the washed chemical liquid as a circulating liquid to the circulation tank 1 through the chemical liquid return pipe 5. In the present invention, the circulating fluid supply system 101 and the circulating fluid return system 102 form a chemical fluid circulating system. In the chemical solution circulation system, a circulation pump 2 is used as power for circulating the chemical solution.

  The membrane treatment by the membrane treatment device 4 is not particularly limited, and for example, ballast water treatment by a ballast water membrane treatment device mounted on a ship can be preferably exemplified.

  Ballast water treatment is processing for introducing ballast water (such as seawater) into the membrane treatment device 4 and generating treated water filtered through a filtration membrane. Along with such membrane filtration treatment, deposits that cause a decrease in flux (amount of treatment during membrane treatment) adhere to the filtration membrane. This deposit is usually derived from components contained in the water to be treated (raw water). If the raw water is seawater, the main component is microorganisms contained in the seawater.

  Normally, deposits on the filtration membrane can be removed by washing without using a chemical solution, such as reverse washing, but depending on the state of adhesion to the membrane, it may not be possible to remove the chemical solution, which requires cleaning with the chemical solution.

  The circulation tank 1 for storing a chemical solution includes an on-off valve (valve) 11 above the circulation tank 1. Specifically, the circulation tank 1 is composed of a main body 1a and a lid 1b. The lid 1b is provided with a deaeration pipe 1c, and the deaeration pipe 1c is provided with a valve 11.

  The circulation tank 1 is configured to be able to seal the inside of the circulation tank 1 by closing the valve 11.

  Reference numeral 12 denotes an upper space formed above the liquid level (water level) S of the chemical solution in the circulation tank 1. The upper space 12 and the deaeration pipe 1c communicate with each other so that gas can pass through. Gas release and sealing can be controlled by the valve 11.

  The valve 11 is not particularly limited, but a normal control valve can be used. The opening and closing may be ON-OFF control or proportional control.

  Further, the circulating tank 1 is provided with a liquid level gauge 13. The liquid level gauge 13 is configured to be able to detect the water level S of the chemical solution in the circulation tank 1 in two stages: a predetermined HL (high level) and a predetermined LL (low level) that is lower than the HL. ing. The water level HL is set at a position lower than the height of the valve 11 from the viewpoint of preventing leakage of the chemical solution from the valve 11.

  In FIG. 1, reference numeral 6 denotes a control unit. The control unit 6 opens and closes the valve 11 based on this detection signal when a detection signal from the liquid level gauge 13 that detects the water level HL or LL is input. The signal can be output. This specific control content will be described below.

  FIG. 2 is a graph showing an example of the change over time of the water level S of the chemical liquid in the circulation tank 1 in the chemical liquid circulation control device of the membrane treatment apparatus according to the present invention, wherein the horizontal axis indicates time and the vertical axis indicates the water level. ing.

  In the chemical solution circulation control device of the membrane treatment apparatus according to the present invention, when cleaning is started, first, the circulation pump 2 is operated to supply the chemical solution in the circulation tank 1 via the chemical solution supply pipe 3. 4 is supplied.

  In this invention, the supplied chemical | medical solution removes the deposit | attachment adhering to the filtration membrane with which the membrane processing apparatus 4 is equipped, and wash | cleans. Further, along with this cleaning, the chemical contained in the chemical solution is decomposed by contact with the deposit and generates gas.

  In the present invention, since it is necessary to generate this gas, the chemical solution preferably contains an agent that generates gas. As such an agent, an oxidizing agent such as hydrogen peroxide can be preferably exemplified. In the case of hydrogen peroxide, it is decomposed by contact with deposits to generate oxygen gas.

  The generated gas is contained as bubbles in the chemical solution. As a result, the apparent volume of the chemical solution increases. The apparent volume of the chemical liquid refers to the volume of the chemical liquid including bubbles contained in the chemical liquid.

  The chemical solution returned to the circulation tank 1 is appropriately adjusted so as to have a predetermined drug concentration as necessary, and then circulated again through the above-described route.

  In the present invention, since bubbles are generated from the chemical liquid by cleaning, the apparent volume of the chemical liquid is increased by including the bubbles, and the water level S of the chemical liquid in the circulation tank 1 is increased.

  The main cause of the rise of the water level S is that the chemical liquid whose apparent volume is increased by containing bubbles is returned to the circulation tank 1.

  Further, even before being returned, the water level S may rise in conjunction with an increase in the apparent volume generated in the circulation system (near the membrane treatment device 4).

  In the present invention, the increase in the level S of the chemical liquid in the circulation tank 1 by the increase in the apparent volume of the chemical liquid containing bubbles generated from the chemical liquid by the control (1) cleaning is performed by the HL (high level) of the liquid level gauge 13. If detected, control is performed to change the valve 11 from open to closed.

  By closing the valve 11, bubbles are separated from the chemical liquid in the circulation tank 1, reducing the apparent volume of the chemical liquid, and the separated bubbles are located above the water level S of the chemical liquid in the circulation tank 1. By expanding the space 12, the water level S decreases.

  In the present invention, after the control (2) valve 11 is closed, bubbles are separated from the chemical solution in the circulation tank 1, the apparent volume of the chemical solution is reduced, and the separated bubbles expand the upper space 12. When the water level drop caused by the above is detected by LL (low level) of the liquid level gauge 13, the valve 11 is controlled to be changed from closed to open.

  The gas collected in the upper space 12 is discharged from the deaeration pipe 1c through the opened valve 11. The degassed gas can be subjected to a detoxification treatment if necessary. However, if the chemical is hydrogen peroxide, the gas generated from the chemical is oxygen gas. It can be discharged to the atmosphere without doing it.

  The chemical solution cleaning is performed while continuing such controls (1) and (2).

  When the cleaning is completed, the circulation pump 2 is stopped.

  According to the present invention, the bubbles in the chemical solution can be suitably removed during cleaning, and the rise in the water level in the circulation tank 1 can be restricted, so that the capacity of the circulation tank 1 can be reduced. Is obtained.

  In the example of FIG. 2, the case where the water level S of the chemical solution in the circulation tank 1 decreases after performing the control (2) for opening the valve 11 is shown. When the amount of gas (bubbles) generated in the circulating chemical solution decreases, the water level S decreases in this way.

  On the other hand, if the amount of gas (bubbles) generated in the circulating chemical solution increases, as shown in FIG. 3, after performing the control (2) to open the valve 11, the chemical solution in the circulation tank 1 The water level S may rise again. When the water level S rises to HL due to this rise, control (1) for closing the valve 11 is performed again. As a result, when the water level S drops again to LL, the control (2) for opening the valve 11 is performed.

  Thus, in the present invention, the controls (1) and (2) can be repeatedly performed according to the generation of gas (bubbles) in the circulating chemical solution, that is, according to the change in the water level S. Particularly in the ballast water membrane treatment apparatus, it is preferable that the membrane treatment apparatus 4 includes a plurality of membrane cartridges. However, in the case where these membrane cartridges are sequentially washed at different timings, as shown in FIG. A method of repeatedly performing the controls (1) and (2) according to the change in the water level S is preferably applied.

  In the present invention, the circulating fluid supply system 101 and the circulating fluid return system 102 supply the chemical solution from the same direction as the raw water supply direction to the membrane at the time of membrane treatment, and collect the chemical solution that has passed through the membrane from the treated water side. Alternatively, the chemical solution may be supplied from the opposite direction, that is, from the treated water side, and the chemical solution that has passed through the membrane may be recovered from the raw water side (backwash). In the case where the chemical solution is washed through the filtration membrane, there is an effect that the washing efficiency of the filtration membrane is further improved.

  Or after making the chemical | medical solution supplied from the raw | natural water side contact with the deposit | attachment of a filtration membrane, you may make it collect | recover from this raw | natural water side, without letting a filtration membrane pass. In the case where cleaning is performed in which the chemical solution does not pass through the filtration membrane, there is an effect that it is possible to further prevent the fine bubbles contained in the chemical solution from remaining in the filtration membrane.

  In the present invention, it is preferable that the circulation tank 1 also serves as a chemical solution generating means. For example, as shown in the figure, it is preferable that the chemical liquid is generated in the circulation tank 1 by adding the chemical supplied from the chemical tank 14 to the water in the circulation tank 1. The circulation tank 1 is preferably provided with a chemical concentration sensor (not shown) so that the amount of medicine supplied from the medicine tank 14 is controlled so that the medicine in the circulation tank 1 has a predetermined concentration.

  On the other hand, the water to which the drug is added for the production of the chemical solution is not particularly limited, but fresh water and seawater from which impurities are appropriately removed can be used, and in particular, after membrane treatment by the membrane treatment apparatus 4 The treated water can be preferably used. Ballast-treated water after membrane treatment can be particularly preferably used.

  Reference numeral 15 denotes a contaminant removal means for removing contaminants in the circulation tank 1, and a circulation pipe 15a connected to the circulation tank 1, a filter 15b provided on the circulation pipe 15a, and a circulation It is comprised by the pump 15c.

  The contaminant removing means 15 has a function of extracting the contaminants in the circulation tank 1 together with the chemical solution by the circulation pump 15c and supplying it to the filter 15b, and returning the chemical solution from which the contaminants have been removed by the filter 15b to the circulation tank 1. .

  In the present invention, the circulation tank 1 preferably includes gas-liquid separation means for promoting separation of the chemical liquid and bubbles. For example, a stationary defoaming tank, a centrifugal separator, a cyclone, a gas-liquid separation membrane, and an ultrasonic wave It is also preferable to use a combination of one or two or more selected from an irradiation apparatus or the like.

  The treatment of ballast water has been described in detail above. However, the present invention is not limited to this, and deposits attached to a filtration membrane included in a membrane cartridge that filters raw water supplied to the raw water chamber to generate treated water in the treated water chamber. Can be widely applied as a chemical cleaning method in the case of efficiently cleaning with a chemical.

W: Chemical solution cleaning mechanism 1: Circulation tank 11: Valve 12: Upper space 13: Water level detection means 14: Chemical tank 15: Contaminant removal means 15a: Circulation piping 15b: Filter 15c: Circulation pump S: Chemical liquid level 2: Circulation pump 3: Chemical solution supply pipe 4: Membrane treatment device 5: Chemical solution return pipe 6: Control unit 101: Circulating fluid supply system 102: Circulating fluid return system

Claims (3)

A circulating fluid supply system for supplying the chemical solution in the circulation tank from the circulation tank to the membrane treatment device with a filtration membrane via the chemical solution supply pipe;
A chemical cleaning system for cleaning and removing deposits adhering to the filtration membrane with the chemical,
A circulating liquid return system for returning the chemical liquid after washing to the circulation tank via a chemical liquid return pipe as a circulating liquid;
Forming a circulation system of the chemical liquid that circulates the chemical liquid by the power of the circulation pump through the circulating liquid supply system and the circulating liquid return system,
The circulation tank is provided with an on-off valve that can seal the inside of the tank, and a liquid level gauge that detects the water level of the chemical in the tank is provided, and the following controls (1) and (2) are performed. A control device for chemical solution circulation in a membrane treatment apparatus.
(1) When an increase in the water level of the chemical liquid in the circulation tank is detected by HL (high level) of the liquid level gauge due to an increase in the apparent volume of the chemical liquid containing bubbles generated from the chemical liquid by the cleaning, Control to change the open / close valve from open to closed.
(2) After closing the on-off valve, bubbles are separated from the chemical liquid in the circulation tank, the apparent volume of the chemical liquid is reduced, and the separated bubbles are above the water level of the chemical liquid in the circulation tank. When the water level drop caused by expanding the upper space is detected by LL (low level) of the liquid level gauge, the on / off valve is controlled to be changed from closed to open.   2. The chemical solution circulation control device for a film processing apparatus according to claim 1, wherein the chemical solution contains at least hydrogen peroxide.   3. The chemical solution circulation control device for a membrane treatment device according to claim 1, wherein the membrane treatment device is a ballast water membrane treatment device mounted on a ship.

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