JP3953673B2 - Membrane separator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a membrane separation apparatus using an internal pressure type tubular membrane as a membrane separation means, and more specifically, a cross flow system capable of increasing the treatment efficiency of membrane separation treatment by increasing the chemical cleaning interval of the tubular membrane. The present invention relates to a membrane separation apparatus.
In the present invention, “tubular membrane” includes both a tube generally called a tubular membrane having an inner diameter of about 5 to 25 mm and a tube generally called a hollow fiber membrane having an inner diameter of about 0.1 to 5 mm. Collectively.
[0002]
[Prior art]
As a means for removing treated water such as general water, power plant condensate, industrial water, etc., or suspended liquid entrained from the liquid to be treated, such as factory waste liquid, to obtain treated water with low turbidity or treated liquid, Conventionally, a membrane separation apparatus using a tubular membrane as a membrane separation means has been widely used.
[0003]
Here, with reference to FIGS. 5 and 6, the configuration of a conventional cross-flow type membrane separation apparatus will be described. FIG. 5 is a flow sheet showing the configuration of a conventional cross-flow type membrane separation apparatus, and FIG. 6 is a longitudinal sectional view showing the configuration of an internal pressure type tubular membrane module used in the conventional membrane separation apparatus.
As shown in FIG. 5, the conventional cross-flow type membrane separation apparatus 10 performs a membrane separation process on the liquid to be treated to flow out a processing liquid having a low turbidity, and flows out a part of the liquid to be treated as a concentrated liquid. A tubular membrane module 12 is provided.
Further, the membrane separation apparatus 10 includes a liquid tank 14 to be processed for storing a liquid to be processed for membrane separation by the tubular membrane module 12, and a liquid to be processed 16 from the liquid tank 14 to be processed to the tubular membrane module 12. The liquid to be processed 18 that is fed via the liquid, the processing liquid tank 22 that stores the processing liquid that flows out from the tubular membrane module 12 via the processing liquid pipe 20, and the liquid to be processed that is concentrated from the tubular membrane module 12. It has a concentrate pipe 24 that returns to the tank 14.
[0004]
As shown in FIG. 6, the tubular membrane module 12 is partitioned in order by a lower partition plate 26 and an upper partition plate 28, and overlaps from the bottom to the top, a liquid distribution chamber 30, a treatment liquid chamber 32, and a concentrated liquid collection chamber. (Hereinafter simply referred to as a liquid collection chamber) 34 and a plurality of internal pressure tubular membranes 38 disposed in the treatment liquid chamber 32.
The tubular membrane 38 has a lower end portion and an upper end portion fixed to the lower partition plate 26 and the upper partition plate 28 so as to communicate with the liquid distribution chamber 30 and the liquid collection chamber 34, respectively, and the inside of the processing liquid chamber 34 is longitudinally directed. Extend to. The tubular membrane 38 is a hollow fiber membrane or a tubular membrane formed of a normal filtration membrane, a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane or the like.
[0005]
The lower partition plate 26 and the upper partition plate 28 are usually formed as an adhesive layer formed by adhering the end portions of the tubular membrane 38 with an adhesive.
The processing liquid chamber 32 is divided into an inner part and an outer part by a tubular film 38, and has a processing liquid port 39 through which the processing liquid flows out by connecting to the processing liquid pipe 20.
In the tubular membrane module 12, the liquid distribution chamber 30 and the liquid collection chamber 34 are formed by the lower end plate 40 and the upper end plate 42, respectively, and communicate with the liquid tube 16 to be processed and the concentrated liquid tube 24. The lower end plate 40 and the upper end plate 42 are connected to the body portion 48 by connecting the flanges 44 and 46 and the flanges 50 and 52 of the body portion 48 forming the processing liquid chamber 32 to be integrated. A container 36 is configured.
[0006]
In the tubular membrane module 12, the liquid to be treated is introduced into the membrane of the tubular membrane 38 through the liquid distribution chamber 30, and membrane separation is performed by the tubular membrane 38 by the crossflow method, so that the treatment liquid is treated in the upper portion of the treatment liquid chamber 32. The liquid is discharged from the liquid port 39 and is stored in the processing liquid tank 22 by the processing liquid pipe 20. At the same time, the liquid to be processed that has passed without passing through the tubular membrane 38 is returned as a concentrated liquid to the liquid tank 14 to be processed by the concentrated liquid pipe 24 via the liquid collection chamber 34.
[0007]
In the present membrane separation apparatus 10, the flow rate of the liquid to be processed flowing in the tubular membrane 38 in the filtration step is high, for example, 0.1 to 1.0 m / second at the outlet of the tubular membrane 38, that is, in the vicinity of the inlet of the liquid collection chamber 34. By setting it as the range, most of the suspension adhered and deposited on the membrane surface of the tubular membrane 38 is peeled off by the hydraulic shear force of the liquid to be treated, and discharged together with the concentrate.
[0008]
After the filtration process as described above is performed for a predetermined time, the tubular membrane 38 is back-washed in order to remove the suspended matter adhering to the membrane surface without peeling. In order to backwash the tubular membrane 38, the membrane separation apparatus 10 uses a treatment liquid as a backwash liquid. Therefore, the backwash liquid pipe 54 connected to the liquid pipe 20 to be treated, and the backwash that feeds the treatment liquid from the treatment liquid tank 22 to the treatment liquid chamber 32 of the tubular membrane module 12 via the backwash liquid pipe 54. A liquid pump 56 and a backwash drainage pipe 58 branched from the liquid pipe 16 to be treated are provided.
At the time of backwashing, the processing liquid as backwashing liquid is fed from the processing liquid tank 22 to the tubular membrane module 12 via the backwashing liquid pipe 54 and the processing liquid pipe 20 by the backwashing liquid pump 56, and the tubular film 38 is reversed. The liquid is discharged to the outside through the liquid distribution chamber 30, the liquid tube 16 to be treated, and the backwash drainage pipe 58 while washing the inner surface of the tubular membrane 38.
Furthermore, if the filtration process and the backwashing process are repeated for a long period of time to perform the filtration treatment of the liquid to be treated, even if the tubular membrane is finally backwashed, the transmembrane pressure difference does not decrease below a predetermined value, that is, Since the filtration performance does not recover, in such a case, chemical cleaning of the tubular membrane is performed using chemicals such as acid, alkali, or oxidizing agent.
[0009]
[Problems to be solved by the invention]
However, in the above-described conventional membrane separation apparatus, the transmembrane pressure difference of the tubular membrane tends to rise in a short time than expected after chemical cleaning, and therefore chemical cleaning is required frequently. There was a problem that the driving efficiency was low.
Therefore, an object of the present invention is to provide a membrane separation apparatus having a configuration that can increase the treatment efficiency of the membrane separation process by increasing the interval of chemical cleaning.
[0010]
[Means for Solving the Problems]
As a result of examining the cause that the transmembrane pressure difference of the conventional membrane separation apparatus rises in a shorter period than expected, the present inventor has found the following.
When the liquid to be treated (hereinafter simply referred to as cross flow circulating water) that has passed through the tubular membrane 38 enters the liquid collection chamber 34, the flow rate is 1/10 to 1 of the flow rate in the tubular membrane 38. / 100 or so. As a result, suspensions separated and entrained by the cross-flow circulating water from the membrane surface of the tubular membrane 38, particularly suspensions having a relatively large particle size, are concentrated liquids based on the specific gravity difference from the liquid to be treated. As shown in FIG. 7, the liquid settles in the liquid collection chamber 34, accumulates on the upper partition plate 28, and then deposits.
The suspension gradually accumulates on the upper diaphragm 28, accumulates on the upper diaphragm 28, eventually falls into the tubular membrane 38 and reattaches to the membrane surface of the tubular membrane 38, Closes the opening at the upper end of the tubular membrane 38, causing an increase in transmembrane pressure difference. As a result, chemical cleaning is required at a short frequency.
[0011]
Therefore, it is considered important to extract the suspension accumulated on the upper partition plate 28 or the accumulated suspension to the outside, and a tubular membrane module provided with an extraction means was prototyped. It came to complete.
[0012]
In order to achieve the above object, a membrane separation apparatus according to the present invention includes a liquid distribution chamber, a treatment liquid chamber, and a concentrated liquid collection chamber defined by a transverse lower partition plate and an upper partition plate in a lower portion, a central portion, and an upper portion. A vertical container having a lower end and an upper end fixed to a lower partition plate and an upper partition plate so as to communicate with a liquid distribution chamber and a concentrated liquid collection chamber, respectively. A tubular membrane module having an internal pressure type tubular membrane extending in the longitudinal direction is provided, the liquid to be treated is introduced into the liquid distribution chamber, the membrane is separated by a cross-flow method, and the processing liquid flows out of the processing liquid chamber and is concentrated. In a membrane separation device that causes the concentrated liquid collection chamber to flow out through the concentrated liquid tube ,
It has a liquid intake port at a position facing the vicinity of the upper partition plate of the concentrated liquid collection chamber, and has a discharge pipe with an on-off valve that penetrates the container wall and goes outside, separately from the concentrated liquid pipe .
[0013]
In the present invention, the number of outlet pipes is not limited, and the number of outlet pipes is determined according to the size of the partition plate. When the number of outlet pipes is one, the pipe diameter of the outlet pipe is preferably in the range of 1/3 to 1/1 times the diameter of the concentrated liquid pipe that causes the concentrated liquid to flow out of the concentrated liquid collection chamber. is there. When there are a plurality of outlet pipes, the total cross-sectional area of the outlet pipes and the cross-sectional area of the concentrated liquid pipe are in this relationship.
The liquid inlet is not necessarily provided flush with the container wall of the concentrated liquid collecting chamber, and the outlet pipe can be inserted into the concentrated liquid collecting chamber and provided at a desired position. At this time, the outlet pipe does not need to penetrate the container wall of the concentrated liquid collection chamber, and may pass through the upper partition plate and pass out of the container wall of the treatment liquid chamber through the treatment liquid chamber. Further, it is not necessary for one outlet pipe to have one liquid inlet, and a plurality of liquid inlets may be provided on one partition pipe in a distributed manner.
As long as the outlet pipe and the on-off valve can withstand the pressure of the liquid to be processed, the shape, material, and material are not limited. In consideration of the flow of the suspension, the on-off valve preferably has an opening area that does not relatively reduce the diameter of the outlet pipe, such as a ball valve or a butterfly valve. .
[0014]
With the above configuration, in the present invention, the suspension can be discharged to the outside through the outlet pipe without being affected by the sedimentation speed of the accumulated suspension and the flow velocity of the cross-flow circulating water.
It is sufficient for the drainage using the outlet tube to be performed periodically or as often as a guide for several tens of seconds once a week during continuous operation of the membrane separator. Sometimes the concentrate may be withdrawn, and the backwash drainage may be withdrawn during the backwash.
The amount of water required for drainage is usually several liters although it depends on the size of the tubular membrane module. Draining is performed using the pressure of the liquid to be treated.
[0015]
The membrane separation apparatus according to the present invention can be applied not only to the properties of the liquid to be treated, but also to, for example, raw water for industrial use and water supply such as river water, well water, lake water, etc. In particular, it can be optimally applied to raw water having a turbidity ranging from several degrees to several hundred degrees, or a liquid to be treated.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below specifically and in detail with reference to the accompanying drawings.
Embodiment Example This embodiment example is an example of an embodiment of a membrane separation apparatus according to the present invention. FIG. 1 is a flow sheet showing the configuration of the membrane separation apparatus of this embodiment example, FIG. FIG. 2A is a cross-sectional view showing the configuration of a tubular membrane module provided in the membrane separation apparatus of this embodiment, and FIG. 2B is a top view of the tubular membrane module.
As shown in FIG. 1, the membrane separation device 60 of the present embodiment has the same configuration as the conventional membrane separation device 10 except for the configuration of the tubular membrane module 62 and piping associated therewith.
[0017]
In the present embodiment example, the tubular membrane module 62 includes a lead-out pipe 64 communicating with the liquid collection chamber 34 as shown in FIG. The outlet pipe 64 has a liquid inlet 66 on the container wall of the upper end plate 42 that forms a concentrated liquid collection chamber (hereinafter simply referred to as a collection chamber) 34 at a position facing the vicinity of the upper partition plate 28. An open / close valve 68 is provided outside. The tube diameter of the outlet tube 64 may be in the range of 25 mm to 50 mm when the inner diameter of the concentrate tube 24 is 50 mm. As shown in FIG. 2B, the lead-out pipe 64 extends in the radial direction with respect to the upper end plate 42, and can be drained to a desired place as shown in FIG.
[0018]
In this embodiment, when the on-off valve 68 is opened periodically or at any time, the concentrated liquid in the liquid collection chamber 34 is applied to the upper partition plate 28 by the pressure of the liquid to be processed, as shown in FIG. The accumulated suspension or accumulated suspension is entrained at once and drained to the outside.
As a result, in the membrane separation device 60 of the present embodiment, the suspension deposited on the upper partition plate 28 falls into the tubular membrane 38 as in the conventional membrane separation device 10, and the membrane of the tubular membrane 38 is obtained. It does not occur that it adheres to the surface again or further closes the opening at the upper end of the tubular membrane 38 and causes an increase in the transmembrane pressure difference.
[0019]
Example of membrane filtration experiment of this embodiment In order to evaluate the performance of the membrane separator of this embodiment, a hollow fiber membrane module (trade name ORFINE) manufactured by Organo Corporation was used as a tubular membrane module. Using this, an experimental apparatus having the same configuration as that of the membrane separation apparatus 62 was produced, and an experiment of membrane filtration was performed under the following conditions.
Treatment liquid: River surface water treatment liquid turbidity: 5 to 500 degrees Filtration water turbidity: 0.0001 to 0.0010 degrees (measured with a laser turbidimeter)
Membrane filtration flux: 1.5 m ³ / m ² / day Concentrate flow rate in the concentrate tube: 0.1 m / second Membrane filtration time from back washing to back washing: 45 minutes Back washing time: 60 seconds Back washing flow Bundle: 5.8 m ³ / m ² / day of drainage frequency from the outlet tube: 1 time / one week of drainage time from the outlet tube: 20 seconds
During the experiment, when the transmembrane pressure difference of the tubular membrane module was measured, the result shown in the graph (1) of FIG. 3 was obtained.
After 7 months, the transmembrane pressure difference of 80 kPa, which required chemical cleaning, was reached. Moreover, the recovery rate of filtered water was 91.40% of the flow rate of river surface water introduced as treated water.
[0021]
Example of membrane filtration experiment of conventional membrane separation device In order to compare with the membrane separation device of this embodiment example, a hollow fiber membrane module (trade name ORFINE) manufactured by Organo Co., Ltd. is also used as a tubular membrane module. Using a conventional membrane separation apparatus using a membrane, a membrane filtration experiment was conducted under the same conditions as those described above, and the transmembrane pressure difference of the tubular membrane module was measured during the experiment. The graph (2) in FIG. The results shown are obtained.
After 4.5 months, the transmembrane pressure difference of 80 kPa, which required chemical cleaning, was reached. Moreover, the recovery rate of filtered water was 91.41% of the flow rate of river surface water introduced as treated water.
[0022]
As can be seen from the above experimental examples, the membrane separation device 60 of the present embodiment has a significantly longer period from the chemical solution cleaning to the chemical solution cleaning than the conventional membrane separation device 10, and the recovery rate of filtered water is high. It is almost the same.
Therefore, it can be evaluated that by using the membrane separation device 60, the processing efficiency of the membrane filtration process is remarkably improved.
[0023]
In the above-described example, the on-off valve 68 is opened periodically or at any time during membrane filtration of the liquid to be treated, and the concentrated liquid is extracted from the outlet pipe 64 to discharge the suspension. Not only at the time of filtration but also at the time of backwashing, the on-off valve 68 may be opened to draw backwashing drainage liquid from the outlet pipe 64, and at the same time, the suspension on the upper partition plate 28 may be drained.
[0024]
Modified example of tubular membrane module This example is a modified example of the tubular membrane module 62 provided in the embodiment. In this example, as shown in FIG. 4, the outlet pipe 70 penetrates the container wall of the upper end plate 42 and penetrates into the liquid collection chamber 34, and a plurality of (two are simply shown in FIG. 4) are taken. The liquid port 72 faces the vicinity of the upper partition plate 28. As shown in FIG. 2, the outlet 72 may be provided with the outlet pipe 70 so as to have a lateral opening along the upper partition plate 28 instead of a downward opening.
Although not shown, as long as the arrangement of the tubular membranes 38 is not affected, the outlet pipe 70 includes a liquid inlet 72 having an upward opening and penetrates the upper partition plate 28 instead of the container wall of the upper end plate 42. And you may make it come out from the container wall of the process liquid chamber 32 outside.
[0025]
【The invention's effect】
According to the configuration of the present invention, the tubular membrane module having an internal pressure type tubular membrane and membrane-separating by the crossflow method has a liquid intake port at a position facing the partition plate of the concentrated liquid collecting chamber, and the container wall By providing a lead-out tube with an on-off valve that passes through the outside, the recovery rate of the membrane separation liquid is the same as that of the conventional membrane separation device, and the period from chemical cleaning to chemical cleaning is significantly increased. Thus, a membrane separation apparatus that significantly improves the efficiency of the membrane separation treatment is realized.
[Brief description of the drawings]
FIG. 1 is a flow sheet showing a configuration of a membrane separation apparatus according to an embodiment.
2A is a cross-sectional view showing a configuration of a tubular membrane module provided in the membrane separation apparatus of the embodiment, and FIG. 2B is a top view of the tubular membrane module.
FIG. 3 is a graph showing a relationship between an operation period and a transmembrane pressure difference.
FIG. 4 is a modified example of a tubular membrane module.
FIG. 5 is a flow sheet showing the configuration of a conventional membrane separation apparatus.
FIG. 6 is a cross-sectional view showing a configuration of a tubular membrane module provided in a conventional membrane separation apparatus.
FIG. 7 is a schematic diagram showing how the suspended matter is deposited on the upper diaphragm.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Conventional cross-flow type membrane separator 12 Tubular membrane module 14 Liquid tank 16 Process liquid pipe 18 Liquid pump 20 Process liquid pipe 22 Process liquid tank 24 Concentrated liquid pipe 26 Lower partition plate 28 Upper partition plate 30 Liquid distribution chamber 32 Treatment liquid chamber 34 Concentrated liquid collection chamber 36 Vertical container 38 Internal pressure tubular membrane 39 Treatment liquid port 40 Upper end plate 42 Lower end plate 44, 46, 50, 52 Flange 48 Body 54 Backwash pipe 56 Reverse Wash pump 58 Backwash drain

Claims (1)

A vertical container having a liquid distribution chamber, a processing liquid chamber and a concentrated liquid collecting chamber divided by a lower partition plate and an upper partition plate in the lower part, center and upper part is provided, and the liquid distribution chamber is provided in the vertical container. And a tubular membrane module having an internal pressure type tubular membrane that is fixed to the lower and upper partition plates at the lower end and the upper end so as to communicate with the concentrated liquid collection chamber and extends in the longitudinal direction in the processing solution chamber. Then, the liquid to be treated is introduced into the liquid distribution chamber, the membrane is separated by a cross flow method, the processing liquid is allowed to flow out of the processing liquid chamber, and the concentrated liquid is allowed to flow out of the concentrated liquid collecting chamber through the concentrated liquid pipe. In the membrane separation apparatus,
A membrane having a liquid intake port at a position facing the vicinity of the upper partition plate of the concentrated liquid collecting chamber, and having a discharge pipe with an on-off valve that passes through the container wall and goes outside, separately from the concentrated liquid pipe Separation device.