JPH02303526A - Membrane separator - Google Patents

Abstract

PURPOSE:To allow efficient filtration and sepn. by connecting pumps via 1st and 2nd circuit to an original liquid introducing port and concn. liquid outflow port of a pressure resistant vessel and connecting the 1st circuit to a washing liquid discharge pipe and the 2nd circuit to a concn. liquid discharge pipe. CONSTITUTION:One end of many hollow fibrous reverse osmosis membranes 6 in the pressure resistant vessel 1 is closed and the hollow holes at the other end are connected to a permeated liquid outflow port 4. The original liquid force fed by a pump 10 connected to the original liquid introducing port 2 from the outer side of the bundle of the reverse osmosis membranes 6 toward a core pipe 5 at the center is passed through the reverse osmosis membranes 6, by which the liquid is separated to the permeated liquid flowing out of the permeated liquid outflow port 4 and the concn. liquid flowing out of the concn. liquid outflow port 3 connected to the core pipe 5. Further, the pump 10 is connected via the 1st and 2nd circuits 15, 17 interposed respectively with valves 14, 16 is connected to the introducing port 2 and the outflow port 3 and the washing liquid discharge pipe 19 is connected from between the valve 14 of the circuit 15 and the introducing port 2 via the valve 18. The concn. liquid discharge pipe 12 is connected from between the valve 16 of the circuit 17 and the outflow port 3 via a pressure regulating valve 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a membrane separation device incorporating a hollow fiber reverse osmosis membrane used for precision filtration, ultrafiltration, reverse osmosis filtration, and the like.

(Prior Art) Conventionally, as shown in FIG. 1, for example, as shown in FIG. A core tube f made of synthetic resin is connected to the stock solution inlet a and has a large number of openings e around it, and a large number of hollow fiber reverse osmosis membranes g are arranged around the core tube f, A structure in which the hollow pores of each hollow fiber reverse osmosis membrane (g) are connected to the permeate outflow port (C) is known. The details of the hollow fiber reverse osmosis membrane g are as shown in the second diagram, one end of the reverse osmosis membrane g is held with an adhesive layer so that the hollow hole i penetrates,
The other end (not shown) closes the hollow hole i and is held by an adhesive layer.

The stock solution to be filtered, purified or separated is processed using a pressure pump.
The stock solution is fed under pressure to the inlet a through the first circuit k, and in the illustrated case, it is passed from the opening e of the core tube f through the reverse osmosis membrane g bundled in a cylindrical shape around the core tube f to the pressure-resistant container. It flows to the peripheral wall portion of d. During this time, the permeate is separated from the stock solution by passing through the reverse osmosis membrane g into its hollow hole i, and the concentrated liquid is concentrated through the separation of the permeate. The concentrate is discharged from the concentrate discharge pipe 0 via the pressure regulating valve l of the second circuit n in which the valve m is arranged in parallel. Further, the permeated liquid that has permeated into the hollow hole i is collected and taken out from the permeated liquid outlet C.

If separation continues, dissolved substances in the stock solution will adhere to the surroundings of the hollow fiber reverse osmosis membrane, reducing the permeability, so sometimes the pumping of the stock solution will be stopped and cleaning liquid will be pumped instead to wash away the deposits. However, in this membrane separator, the flow of the liquid is the same in this case as in the filtration operation, and the cleaning liquid is introduced from the raw solution inlet a through the first circuit k by the pressure pump j. The concentrate is discharged from the outlet through the automatic opening/closing valve m of the second circuit n.

In addition, a third
As shown in the figure, a liquid feed pump p and a pressure pump j are provided in two stages, a check valve q is interposed in the first circuit k, and a circuit connecting the liquid feed pump p and pressure pump j is connected to the first circuit. to, check valve q′
It is also practiced to connect a branch path r provided with a branch path r.

Even in the device shown in the third figure, the way the liquid flows is fundamentally unchanged; the raw liquid during filtration operation is pumped by the liquid feed pump p and the pressurizing pump j, and is then pumped through the check valve q. Stock solution inlet a
The cleaning liquid used in the cleaning operation is fed by the liquid feeding pump p with the pressurizing pump j stopped, and is introduced from the raw liquid inlet a through the check valve q' of the branch path r.

The subsequent flow of liquid is exactly the same as in the device described above.

As the stock solution, water containing common minerals such as city water and well water, various aqueous solutions containing proteins, sugars, etc. are used, and ions, bacteria, and dissolved substances in the stock solution are removed by a reverse osmosis membrane. The filtered permeate is separated into a concentrated solution of the stock solution.

(Problems to be Solved by the Invention) As mentioned above, the membrane separation device using the conventional hollow fiber reverse osmosis membrane is designed to perform filtration and cleaning by pumping liquid from the center to the outer periphery of the reverse osmosis membrane, which is bundled into a cylindrical shape. Because it is designed to flow, during filtration, each hollow fiber reverse osmosis membrane is expanded outward by the flow of liquid, pulling the core tube at the center of the reverse osmosis membrane bundled into a cylinder. In particular, when the stock solution is flowing at a high flow rate or the stock solution is a high viscosity liquid, this force becomes large and the core tube may break.

In addition, the flow of liquid is fast at the center of the bundled reverse osmosis membranes, and the flow becomes slower toward the outer periphery, so that the concentrated liquid tends to stagnate at the outer periphery, resulting in poor filtration efficiency.

Furthermore, during cleaning, it is necessary to wash away dirt adhering to the center of the bundled reverse osmosis membranes to the outer periphery, and the cleaning effect is not good.

SUMMARY OF THE INVENTION An object of the present invention is to provide a membrane separation device that allows a cleaning solution to be flowed in such a manner that adhered dirt can be easily removed without causing stagnation of the concentrated solution or bending of the core tube.

(Means for Solving the Problems) In the present invention, a pressure-resistant container equipped with a stock solution inlet, a concentrate outlet, and a permeate outlet has a large number of openings around the periphery connected to the concentrate outlet. A core pipe is provided, a large number of hollow fiber reverse osmosis membranes are bundled along the circumference of the core pipe,
One end of each hollow fiber reverse osmosis membrane is closed, a hollow hole at the other end is connected to the permeate outflow port, and a pump connected to the stock solution inlet is used to enter the central core tube from the outside of the reverse osmosis membrane bundle. The stock solution that is pumped toward is separated into a permeate that passes through the reverse osmosis membrane and flows out from a permeate outlet, and a concentrate that flows out from a concentrate outlet connected to the core tube. At the same time, a pump is connected to the raw solution inlet and the concentrated solution outlet through first and second circuits each having a valve interposed therebetween, and a pump is connected to the raw solution inlet and the concentrated solution outlet through the valve from between the valve of the first circuit and the concentrated solution inlet. The above object is achieved by connecting a cleaning liquid discharge pipe and further connecting the concentrated liquid discharge pipe from between the valve of the second circuit and the concentrated liquid outlet via a pressure regulating valve.

(Function) The stock solution that is pumped to the stock solution inlet via the first circuit flows from near the inner wall of the pressure container into the core pipe through a hollow fiber reverse osmosis membrane bundled around the core pipe. Therefore, there is no stagnation in the flow of the liquid, and during that time, the permeate that has permeated through the reverse osmosis membrane is separated and flowed out from the permeate outlet, and the stock solution that has flowed into the core pipe becomes a concentrated liquid and is discharged from the concentrate outlet. It passes through a pressure regulating valve and is discharged to the concentrate discharge pipe.

In addition, even when the stock solution is passed at a high flow rate, the bundled hollow fiber reverse osmosis membrane does not spread outward, and the core tube does not break.

If such separation continues, dissolved substances in the stock solution will adhere to the outer circumferential surface of the reverse osmosis membrane, reducing the permeability, but in this case, the first circuit valve is closed, the second circuit valve is opened, and the pump pumps the stock solution. The cleaning liquid is pumped instead. As a result, the cleaning solution flows into the pressure container from the concentrate outlet, flows from the core pipe around the hollow fiber reverse osmosis membrane in the opposite direction to the flow of the stock solution, flows out from the stock solution inlet, passes through the valve, and the cleaning solution passes through the valve. It is discharged into the exhaust pipe. The flow of the cleaning solution is opposite to that of the stock solution, so
It is possible to cleanly wash out the dissolved substances in the stock solution that tend to adhere in large quantities around the reverse osmosis membrane on the upstream side of the flow of the stock solution, and the washing operation can be performed at any time relatively easily by opening and closing the valve.

(Example) An example of the present invention will be explained based on FIG. 4) a cylindrical pressure vessel, (5) a core tube with a number of openings (Iv) connected to the concentrate outlet (3) and extending into the pressure vessel (1); 6) shows a large number of hollow fiber reverse osmosis membranes provided around the core tube (5) along its length.

The reverse osmosis membrane (6) is made of cellulose acetate fibers, for example, and has hollow holes as shown in the second figure, both ends of which are held by adhesive layers (7) and (8), and one end of which is hollow. It is held so that the hole passes through the adhesive layer (D) and continues to the permeate collection chamber (9), and the other end is held so that the hollow hole is closed (for example, Toyobo M■, HR8355).
IR5330 membrane).

This configuration is the same as the conventional one except for the direction in which the liquid flows, and when the stock solution in which the dissolved substance is dissolved is pumped to the stock solution inlet (2) by the pressure pump GO, the stock solution is transferred to the pressure container (
1) flows around the hollow fiber reverse osmosis membrane (6) into the core tube (5) through the opening qv without stagnation, during which the clean water permeates through the reverse osmosis membrane (6). The permeate is separated and discharged via the permeate outlet (4). Then, the remaining stock solution from which the permeate has been separated is discharged as a concentrate from the concentrate outlet (3) to the concentrate discharge pipe (2).

In order to permeate the reverse osmosis membrane (6), it is necessary to increase the pressure within the pressure vessel (1), and this pressure is maintained by the pressure regulating valve a3.

When the separation of the stock solution continues, dissolved substances in the stock solution pass through the reverse osmosis membrane (
6), and the transmittance decreases, so it is necessary to remove the deposits by flowing a cleaning solution.However, in the present invention, for example, an automatic Open/close valve aΦ
It is connected to the pressurizing pump (1 (+1) through the first circuit 09 equipped with It is connected to the pressure pump 00, and connected to the cleaning liquid discharge pipe (+9) from between the on-off valve aΦ and the stock solution inlet (2) of the first circuit (Is) via the on-off valve Ge, and the second circuit 07 ) between the on-off valve CO and the concentrate outlet (3) is connected to the concentrate discharge pipe ■ via the pressure regulating valve 03, and the on-off valve (14) (inside the pressure vessel (1) Cleaning was performed by flowing the cleaning liquid in the opposite direction to the flow of the stock solution.■ is an on-off valve that is provided as necessary.

To explain its operation, when separating the stock solution, open the on-off valve (+4) ■, close the on-off valve ae aa, and transfer the stock solution from the pressure pump (IO to the pressure container (1) through the second circuit 07.
). As a result, as described above, the permeate is separated and discharged from the stock solution through the reverse osmosis membrane (6), and the remaining concentrate is discharged from the concentrate discharge pipe (+21) via the pressure regulating valve q3.

In this case, since the stock solution flows from the outer periphery to the center of the reverse osmosis membrane (6), no stagnation occurs in the flow of the solution, and efficient filtration and separation can be performed.

When cleaning the deposits that have adhered to the circumferential surface of the reverse osmosis membrane (6) due to separation, the on-off valve aΦ■ is closed, and the on-off valve (l
e (18 is opened. Then, when the pressure pump (+0) is used to pump the cleaning liquid instead of the stock solution, the cleaning liquid flows into the second circuit 07.
) flows into the concentrate outlet (3), flows in the pressure container (1) in the opposite direction to the flow of the concentrate, flows out from the concentrate inlet (2), and is discharged from the cleaning liquid discharge pipe (2). In this case, the deposits on the circumferential surface of the reverse osmosis membrane (6) are cleanly peeled off by the flow of the cleaning liquid in the direction opposite to that of the undiluted solution, and are removed from the discharge pipe a9.

In order to forcefully feed the stock solution and cleaning liquid, it is also possible to install a liquid feeding pump (2) upstream of the pressurizing pump aO as shown in Figure 5. In this case, the cleaning liquid that does not need to be under high pressure can be used. The liquid can be sent to a second circuit (2) which is branched from the outlet of the liquid sending pump 0. In addition, as shown in Figure 5, the on-off valve (14) of the first and second circuits Cl5) (+?)
It is also possible to use a check valve as ae and a pressure regulating valve (Ie that has a valve closing function) to omit providing an on-off valve in front of it.

A comparison between the conventional device and the device of the present invention was as follows.

In the conventional apparatus shown in Figure 1, approximately 5% sugar waste liquid was passed as a stock solution at a flow rate of 2 J/min and a pressure of 50 kg/cd.
While obtaining a permeate of 7w1n, the permeate was washed once every two days with water containing 1 Oppi of sodium hypochlorite, and the pressure reached 55kg/cd in two weeks.
The permeated liquid became almost 0, and the reverse osmosis membrane was damaged. In this case, the hollow fiber reverse osmosis membrane of Toyobo ■)
An IR5255 membrane (5 inch diameter, 2 feet long) was used. When the pressure vessel was dismantled and inspected, the core tube was broken and the hollow fiber reverse osmosis membrane on the inner wall side of the pressure vessel was almost free of dirt, but the reverse osmosis membrane near the core tube had accumulated dirt. Ta.

In the apparatus of the present invention shown in Fig. 4, the cleaning apparatus is operated once every two days using water containing 109p of sodium hypochlorite as a cleaning liquid, and approximately 6% maltose waste liquid is supplied at a flow rate of 801/1n.
When it was flowed at a pressure of 50 kg/c- to obtain a permeate of 201/sin, it could be operated for one year without any abnormality. In this case, Toyobo's HR8355 membrane (diameter: 8 inches, length: 3 feet) was used as the hollow fiber reverse osmosis membrane.

As a result of dismantling and inspecting the pressure vessel, a slight amount of dirt was found on the hollow fiber reverse osmosis membrane near the inner wall of the pressure vessel, but most of the dirt was on the reverse osmosis membrane near the core tube. I hadn't.

Furthermore, when the apparatus of the present invention shown in Figure 5 was operated once every two months using 2x citric acid aqueous solution as the cleaning liquid, it was operated over city water for two years without any abnormalities. In this case, an HR5330 membrane (5 inches in diameter, 3 feet in length) manufactured by Toyobo Co., Ltd. was used as the hollow fiber reverse osmosis membrane. As a result of dismantling and inspecting the pressure vessel, it was found that the hollow fiber reverse osmosis membrane on the outer periphery near the inner wall of the vessel was slightly discolored due to iron contamination, but there was almost no discoloration on the membrane in the center near the core pipe. There was no dirt attached.

(Effects of the Invention) As described above, according to the present invention, the pump is connected through the first and second circuits each having a valve at the stock solution inlet and concentrate outlet of the pressure-resistant container, and from the first circuit Since it is connected to the washing liquid discharge pipe through a valve and the concentrated liquid discharge pipe is connected from the second circuit through a pressure regulating valve, the flow of the stock solution is directed to the outer periphery of the bundled hollow fiber reverse osmosis membrane. The flow rate does not slow down and there is no stagnation in the flow of the liquid, which not only allows for efficient filtration and separation, but also allows the washing liquid to be flowed at any time in the opposite direction to the flow direction of the stock solution. The method has the following advantages: it can perform thorough cleaning, it can continue separation for a long period of time without replacing the reverse osmosis membrane, and its cleaning operation is relatively simple.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the conventional example, Figure 2 is an enlarged view of the main parts, and Figure 3 is an explanatory diagram of the conventional example.
FIG. 4 is an explanatory diagram of another conventional example, FIG. 4 is a detailed explanatory diagram of the present invention, and FIG. 5 is an explanatory diagram of another embodiment of the present invention.

Claims (1)

[Claims] In a pressure-resistant container equipped with a raw solution inlet, a concentrate outlet, and a permeate outlet, a core tube connected to the concentrate outlet and having many openings is provided around the core tube, and a large number of openings are provided around the core tube. Hollow fiber reverse osmosis membranes are bundled together, one end of each hollow fiber reverse osmosis membrane is closed, the hollow hole at the other end is connected to the permeate outflow port, and a pump connected to the stock solution inlet is used. The stock solution is pumped from the outside of the bundle of reverse osmosis membranes toward the central core tube, the permeate passes through the reverse osmosis membranes and flows out from the permeate outlet, and the concentrated liquid stream is connected to the core tube. The first valve is configured to separate the concentrated liquid flowing out from the outlet, and has valves interposed in the raw liquid inlet and the concentrated liquid outlet, respectively.
and a pump via a second circuit, a cleaning liquid discharge pipe is connected via a valve between the valve of the first circuit and the raw solution inlet, and further a cleaning liquid discharge pipe is connected between the valve of the second circuit and the concentrate outlet. A membrane separation device characterized in that the concentrated liquid discharge pipe is connected through a pressure regulating valve between the membrane separators.