JP3402908B2 - Filtration device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of a fluid overflowing a circulation path during backwashing in a filtration device using a cross-flow type membrane-utilizing filtration means.

[0002]

2. Description of the Related Art Conventionally, as a filtering device used for reusing a cleaning liquid or for treating waste water, there is a filtering device which uses a membrane-utilizing type filtration means using a microfiltration membrane or an ultrafiltration membrane.

This is because, for example, a cleaning liquid in which oil to be filtered is mixed is filtered through a membrane having fine pores that are much smaller than the size of the oil droplets to separate the oil from the cleaning water. To obtain a cleaning liquid that does not contain

FIG. 2 shows an example of a conventional filtration device utilizing a membrane-utilizing filtration means. The filtering device 100 is connected to, for example, a cleaning tank 101 that removes dirt and oil adhering to the workpiece W101 to be cleaned. The cleaning tank 101 has a cleaning liquid L101 containing water and a detergent as main components.
Then, the work W101 is dipped thereinto to remove stains and oils by a chemical action of a detergent component or a physical action such as ultrasonic waves, stirring, and shaking. Here, 102 is illustrated as an ultrasonic oscillator.

When the works W101 are continuously put into the cleaning tank 101, the cleaning liquid L in the cleaning tank 101 is continuously supplied.
The oil concentration of 101 increases and the cleaning ability for the work decreases. However, by removing oil from the cleaning liquid L101 and appropriately adding detergent, the cleaning liquid L101
It is possible to reproduce 101.

Accordingly, the filtration device 100 described herein.
Uses the cleaning liquid L101 as a fluid to be filtered, removes oil and foreign matter contained therein, and removes the cleaning liquid L101.
Is a device intended to reproduce.

The filtration apparatus 100 of FIG. 2 has a large-sized open type concentration tank 104 provided in a circulation path K101 with a cleaning liquid L101 which is a fluid to be filtered supplied through a supply path 103 connected to a cleaning tank 101. Accumulate in.
The cleaning liquid L104 in the concentration tank 104 is the pump 10
The hollow fiber membrane module 106 is pressurized and accelerated by
And is subjected to cross-flow filtration. The membrane permeate is returned to the cleaning tank 101 through the return paths 107a and 107b. The liquid that has not permeated the membrane is concentrated and returned to the concentration tank 104, and the circulation path K1 is reached to the concentration limit.
It is circulated in 01.

Further, when the hollow fiber membrane module 106 is subjected to a filtration treatment for a certain period of time, impurities are deposited on the surface of the membrane and become clogged, and the filtration capacity is lowered. So pump 1
After stopping 05, the switching valve 109 is switched to apply a reverse pressure such as compressed air to the backwash tank 108, and the return path 1
The clean membrane permeate stored in the backwash tank 108 provided at 07a is backwashed by permeating the membrane of the hollow fiber membrane module 106 in the reverse direction.

The backwashing waste liquid which has permeated in the reverse direction through the film overflowing from the circulation path K101 by the backwashing is returned to the concentration tank 104.

However, in this filtration device 100, the flow rate of the fluid flowing in the circulation path K101 is several tens of times (about 10 to 100 times) of the generated membrane permeate, and it is necessary to operate the device stably. A large concentration tank 104 is required, and the size of the device itself becomes large. Further, the concentration tank 104 is large, and the hold-up amount (the amount of the filtration target fluid necessary to maintain the operation) of the filtration target fluid in the concentration tank 104 that enables the device to operate becomes large, and the operation is performed in a batch process. Has the problem of low efficiency.

Therefore, in order to solve the above-described problems of the prior art, a filter device 200 having a closed circulation path K201 has been proposed in FIG. The same reference numerals will be given to the components of the filtering device 200 that perform the same operations as those of the filtering device 100.

A cleaning liquid L101, which is a fluid to be filtered, supplied from the cleaning tank 101 via a supply path 201 equipped with a check valve 202 is connected to a circulation path K201.
In the circulation route K201, the pump 105 is used as in the device of FIG.
And the cross-fiber filtration is performed by circulating the fluid to be filtered by the hollow fiber membrane module 106. In addition, it is the same that backwashing needs to be performed after every operation for a certain period of time.

[0013]

However, in the case of performing backwashing in this filtration device 200, unlike the above-mentioned filtration device 100, the circulation route K201 is backwashed by permeating the membrane in the reverse direction by backwashing. There is no concentrated tank acting as a buffer for temporarily storing the waste liquid, and when backwashing is performed, the concentrated liquid in the circulation route K201 flows back and the washing tank 101
Will return to. If even a small amount of the concentrated liquid flows back into the cleaning tank 101, the concentration of oil in the cleaning liquid in the cleaning tank 101 will be increased immediately and the cleaning ability will be reduced, and the effect of the filtration process will be lost.

Therefore, in this filtering device 200, the backflow prevention valve 2 is switched before the switching valve 109 is switched to perform backwashing.
02 is closed and the discharge valve 203 is opened, and backwashing is performed in this state. Then, the concentrated liquid that overflows from the circulation path K201 by the backwash and the backwash waste liquid that has permeated the membrane in the opposite direction are discharged into the waste liquid tank 204.

Therefore, as a problem of the filtering apparatus 200, since backwash waste liquid is generated every time backwash is performed, a large amount of backwash waste liquid is generated when backwashing is performed frequently.

Further, since it is necessary to operate the backflow prevention valve 202 and the discharge valve 203 when performing the backwash, the operation becomes complicated. When this operation is automatically controlled, the control system becomes complicated.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object thereof is to efficiently backwash the membrane-utilizing filtration means provided in the filtration device. Prevents backflow during backwash with a simple structure,
(EN) Provided is a small-sized and easy-to-operate filtration device that enables recycling of waste liquid.

[0018]

In order to achieve the above object, in the present invention, a cross-flow type membrane-utilizing type filtration means and the membrane-utilizing type filtration means are disposed in a path to perform filtration. Filtration provided with a circulation path through which the target fluid circulates, a supply path for supplying the target fluid to be filtered to this circulation path, and a backwash means for permeating the fluid in a direction opposite to the permeation direction of the membrane of the membrane-utilizing type filtration means. In the device, the reverse
The volume of fluid accumulated in the backwash means that flows back during washing.
A storage means for storing the fluid set to a capacity larger than the volume and overflowing the circulation path during backwashing is provided.

As a result, the fluid overflowing the circulation path due to the backwash is accumulated by the accumulating means, and after the backwash is completed, it is resupplied from the supply path to the circulation path as the fluid to be filtered.

It is also preferable that the storage means also serves as a housing of the strainer.
Therefore, the housing of the strainer that removes coarse dust and foreign matter in the fluid to be filtered is also used as the accumulating means.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the illustrated embodiments.

(Embodiment 1) FIG. 1 is a first embodiment schematically showing a filtration device to which the present invention is applied.
This filtering device S1 is, for example, a work W1 to be cleaned.
It is provided in the cleaning tank 1 for removing dirt and oil attached to the. The cleaning tank 1 is filled with a cleaning liquid L1 containing water and a detergent as main components, and the work W1 is immersed in the cleaning liquid L1 by a chemical action of the detergent component or a physical action such as ultrasonic wave, stirring, and shaking. It removes dirt and oil. Here, 2 is exemplified as the ultrasonic oscillator.

The cleaning liquid L1 whose oil component concentration has increased due to the cleaning and has become dirty passes through the supply paths 3a and 3b and the circulation path K.
1 is supplied. Reference numeral 4 is a strainer configured to function as a storage means. The strainer 4 is generally for filtering dust and coarse impurities contained in the fluid by the filter net 4a, but is provided with a housing 4b functioning as an accumulating unit under the filter net 4a. The capacity of the housing 4b is set to be larger than the capacity of the membrane permeate L2 accumulated in the backwash tank 8 which flows back in the permeating direction of the membrane during backwashing.

Further, 5 is a pump, 6 is a hollow fiber membrane module, 7a and 7b are return paths for returning the membrane permeate L2 to the washing tank 1, 8 is a backwash tank as backwash means, and 9 is a switching valve. is there. The state of performing normal filtration is the same as that of the filtration device 200 according to the related art shown in FIG.

The state in which backwashing is performed in this filtering device will be described. First, the pump 5 is stopped to stop the concentrated liquid flowing inside the circulation route K1. Next, the switching valve 9 is switched to send the compressed air indicated by the arrow A1 to the backwash tank 8, and the membrane permeate L2 is sent out from the backwash tank 8 in the direction opposite to the permeation direction of the membrane to start the backwash. .

Then, the concentrated liquid and the backwashing waste liquid overflowing from the circulation route K1 during the backwashing flow back through the supply route 3b and are accumulated inside the housing 4b of the strainer 4. Since the capacity of the housing 4b is larger than the amount of backwash waste liquid generated,
The backwash waste liquid does not flow back through the supply path 3a and is returned to the washing tank 1.

When backwashing is completed, the switching valve 9 is switched and the pump 5 is started to perform filtration again. Then, the backwash waste liquid accumulated in the housing 4b is also gradually supplied to the circulation path K1 as the fluid to be filtered.

Therefore, when backwashing is performed, the backwashing waste liquid is accumulated inside the housing 4b of the strainer 4 which is the accumulating means provided in the supply path, and flows back into the cleaning tank 1 upstream of the supply path. There is nothing to do. Further, since the backwash waste liquid becomes the fluid to be filtered again in the subsequent normal filtering operation, the waste liquid is not generated every backwash. Further, the housing 4b of the strainer 4 also serves as the accumulating means, so that the size can be easily reduced. Further, a valve or the like for controlling the backwashing waste liquid flowing back is not required, and the operation is extremely simple with a simple configuration.

(Embodiment 2) In the first embodiment of the present invention shown in FIG. 1, a strainer 4 and a hollow fiber membrane module 6 are used as a filtering means for the cleaning liquid L1, and an oil removing means (not shown) is used. Was used to adjust the oil concentration of the concentrated liquid circulating in the circulation route K1.
2 for explaining the embodiment of the present invention shows a filtering device S2 to which an oil removing means is added as a device configuration,
This will be described below.

This filtering device S2 is provided with bypass paths 11a and 11b inside the circulation path K2, and a floating oil recovery means 12 is incorporated therein as an oil content removal means for removing the oil content in the concentrated liquid concentrated by circulation. belongs to. In other configurations, the same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

Then, the opening of the flow control valve 10 is adjusted to guide a part of the concentrated liquid circulating in the circulation route K2 to the floating oil recovery means 12 via the bypass route 11a to recover the oil content in the concentrated liquid. To reduce the oil concentration. The concentrated liquid with reduced oil concentration is returned to the circulation route K2 by the bypass route 11b. The collected oil is discharged to the outside from the discharge port 12a.

Therefore, in this filtering device S2, the discharge speed of the recovered oil and the oil carry-in speed by the cleaning tank 1 (actually, the oil adhering to the work W1) are made substantially equal to each other, so that the circulation path K2 inside It is possible to stabilize the oil concentration of the concentrated liquid at a constant rate, and the hollow fiber membrane module 6 is operated under a constant load to efficiently filter, and it is possible to continuously perform the filtration for a long period of time.

[0033]

As described above, the present invention does not require a valve or the like for controlling the backwashing waste liquid overflowing from the circulation path, and prevents backflow during backwashing with a simple device configuration.
Further, it is possible to reduce the size of the filtration device. Further, the backwash waste liquid becomes the fluid to be filtered again when the backwashing is completed and the filtration device is in the normal filtration operation, so that no waste liquid is generated in each backwash, and the amount of waste liquid is reduced.

[Brief description of drawings]

FIG. 1 is a diagram of a filtration device according to a first embodiment of the present invention.

FIG. 2 is a diagram of a filtering device according to a second embodiment of the present invention.

FIG. 3 is a diagram of a conventional filtration device.

FIG. 4 is a diagram of a conventional filtration device.

[Explanation of symbols]

1 cleaning tank 2 Ultrasonic oscillator 3a, 3b supply route 4 strainers 4a filtration net 4b housing (storage means) 5 pumps 6 Hollow fiber membrane module 7a, 7b Return path 8 backwash tank 9 Switching valve 10 Flow control valve 11a, 11b bypass route 12 Floating oil recovery means K1, K2 circulation path L1 cleaning solution L2 membrane permeate S1 filtering device W1 work

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) C02F 1/44 B01D 61/00

Claims (2)

(57) [Claims] 1. A cross-flow type membrane-utilizing type filtration means, a circulation route in which the membrane-utilizing type filtration means is disposed, and a fluid to be filtered circulates, and a fluid to be filtered is supplied to this circulation route. In a filtration device comprising a supply path and a backwash means for permeating a fluid in a direction opposite to the permeation direction of the membrane of the membrane-utilizing type filtration means, in the supply path , accumulation in the backwash means for backflow during backwashing.
A filtering device comprising a storage means for storing a fluid which is set to a capacity larger than that of the fluid being stored and which overflows the circulation path during backwashing. 2. The filtering device according to claim 1, wherein the accumulating means also serves as a housing of the strainer.