JPH10290925A - Liquid separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To intermittently take out permeated liquid without stopping a feed pump to unnecessitate a large permeated liquid tank by branching a pipeline on the permeated side of a separation membrane into take-out piping for the permeated liquid and return piping for circulating the permeated liquid to the original liquid feed side of a separation membrane. SOLUTION: Original liquid before treatment is separated into permeated liquid and nonpermeated liquid by a separation membrane module 3 from an original liquid tank 1 through suction piping 71, pressurizing pump 2, and feed piping 72. Permeated side piping 74 is branched into take-out piping 76 and return piping 75, which are provided with automatic stop valves 62, 63 respectively to control flow directions of the permeated liquid. The permeated liquid is normally taken out to outside equipment through the permeation side piping 74, the automatic stop valve 62, and the take-out piping 76, and the automatic stop valve 63 is closed. When the automatic stop valve 62 is closed, the automatic stop valve 63 is opened to cause the permeated liquid to flow in the return piping 75 and is returned to the suction piping 71 by the suction of a pressurizing pump 2 and release the pressure on the permeated side of the separation membrane to the feed side. With the pressurizing pump 2 in stationary operation, the take-out piping 76 is closed to enable the replacement of a permeated liquid recovery vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid separation apparatus for performing a liquid concentration or fresh water operation using a separation membrane module.

[0002]

2. Description of the Related Art In liquid separation membranes, in order to increase the amount of permeate, a composite membrane in which an active skin layer having a selective separation function is provided on a porous support membrane is widely used. As the liquid separation device, the active skin layer of the composite membrane is supplied on the supply side,
Generally, a configuration is provided in which a stock solution pressurized by a pump is supplied to a membrane module having a porous support membrane on a permeation side, and a permeate is continuously taken out by a pressure difference from the permeation side.

[0003] A disadvantage of the composite membrane is that the active skin layer is more easily peeled off than the porous layer due to the pressure applied from the permeation side, that is, the back pressure. Therefore, conventionally, roughly two means have been adopted to prevent the peeling of the active skin layer.

As shown in FIG. 2, for example, as shown in FIG. 2, the first prevention means releases the permeate-side pipe 91 to the atmosphere without disposing a valve operated during operation on the permeate side of the separation membrane 9, and simultaneously releases the permeate-side pipe 91 to the atmosphere. The permeated liquid taken out from the side pipe 91 is temporarily stored in a permeated liquid tank 92, and the on-off valve 93 of the tank 92 is opened as necessary to take out the permeated liquid. According to this method, the back pressure is not applied to the separation membrane 9 because the permeation side pipe 91 is always open to the atmosphere.

[0005] The second prevention means is to arrange a stop valve 93 and a gate valve 94 in the pipe path of the permeation side pipe 91 as shown in FIG. 3, for example. In this case, when distributing the permeated liquid to the container 96, the stop valve 93
Is opened, the gate valve 94 is closed, and when the process shifts to the distribution to the container 97, the pump on the supply side is temporarily stopped, the stop valve 93 is closed, the gate valve 94 is opened, and the pump is operated again. As a result, at least during the operation of the pump, the permeation-side pipe 91 is open to the atmosphere.
No back pressure.

[0006]

However, there is not always a space in which the permeated liquid tank 92 can be always installed as in the first means. Therefore, when space saving is required, the first means cannot be adopted. Further, in the second means, stopping the supply pump every time the permeated liquid is distributed to the individual containers is caused by time loss for returning to the original operating pressure again, and repeated stop / start of the pump motor. Not only is the life of the pump shortened, but there is even the danger that the membrane may be damaged by back pressure if the permeate tube path cannot be released to the atmosphere for any reason.

Therefore, an object of the present invention is to provide a liquid separating apparatus which can intermittently take out a permeate without stopping a supply pump and does not require a permeate tank having a large occupied area. .

[0008]

In order to achieve the above-mentioned object, in the liquid separation apparatus of the present invention, a pipe path on the permeation side of the separation membrane is connected to a take-out pipe for extracting permeate and a stock solution supply side of the separation membrane. It is characterized by being branched to a circulating return pipe.

According to the present invention, the permeate can be freely taken out from the take-out pipe. And even if the take-out pipe is closed when distributing the permeate, the pressure on the permeate side of the separation membrane escapes to the supply side through the return pipe, so the pressure does not rise above the pipe resistance, and the pipe resistance is smaller than the membrane outlet pressure. Is normal, so there is no back pressure. The take-out pipe is not always in communication with the atmosphere at the end, and may be connected to the supply side of the separation membrane in the next stage.

[0010] A pump for supplying the undiluted solution is installed in the undiluted liquid supply side pipe route, and if the connection position between the return pipe and the undiluted solution supply side pipe route is the suction side of the pump, the undiluted solution is supplied by one pump. It is preferable because the supply and the return of the permeate can be performed simultaneously, and the pressure difference between both sides of the separation membrane can be maintained. In addition, if the open / close valve is arranged in each of the take-out pipe and the return pipe, it is easy to switch the flow path of the permeated liquid.

In addition to the above-mentioned configuration, a flow meter and / or a pressure gauge is installed in the pipe line on the permeation side, and a control device for controlling the opening / closing operation of each of the on-off valves according to the detection values of these instruments is provided. And good. As a result, each on-off valve is automatically operated to distribute the permeate to the return pipe before a sign of membrane breakage due to peeling occurs, and the on-off valve automatically returns again when the permeate pressure becomes normal. This is because the permeated liquid can be taken out and flown to the piping.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid separating apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a flow chart of a liquid by the liquid separation device of the embodiment.

In this apparatus, the stock solution before processing is stored in a stock solution tank 1, from which the stock solution is sucked into the pressurizing pump 2 through the suction pipe 71 of the pressurizing pump 3 and pressurized. The pressurized stock solution is sent to the separation membrane module 3 through the supply pipe 72, and separated into the non-permeate liquid remaining on the non-permeate side 31 of the separation membrane and the permeate liquid permeating the permeate side 32 in the separation membrane module 3. Is done. Non-permeated liquid is pressure regulating valve 6
After that, the liquid is returned to the stock solution tank 1 through the non-permeate side pipe 73. The flow rate of the supplied undiluted solution and the flow rate of the permeated liquid, and the pressure of the undiluted solution and the non-permeated liquid are measured by a pressure gauge 41 and a pressure gauge 42, respectively.
, And is controlled by adjusting the pressure adjusting valve 61.

On the other hand, the transmission side pipe 74 is connected to the extraction pipe 7.
6 and a path toward the return pipe 75, and the direction in which the permeated liquid actually flows is controlled by the automatic opening / closing valves 62 and 63 disposed in each path. That is,
The permeated liquid always passes through the permeation side pipe 74, and the automatic on-off valve 62
After passing through the permeated liquid flow meter 5, the liquid is taken out of the liquid separation device through the take-out pipe 76 and becomes atmospheric pressure. During this time, the automatic on-off valve 63 is closed. However, the automatic on-off valve 62
Is closed, the automatic on-off valve 63 is opened to allow the permeated liquid to flow to the return pipe 75 and to be returned to the suction pipe 71 by the suction of the pressurizing pump 2. Thereby, the pressure on the permeation side of the separation membrane escapes to the supply side through the return pipe.
Therefore, with the operation of the pressure pump 2 kept constant, the take-out pipe 76 can be closed and the permeated liquid recovery container can be replaced. Since the return pipe 75 is provided with the check valve 8, the permeated liquid does not flow backward, and the undiluted liquid does not enter the permeation-side pipe 74 without passing through the separation membrane module 3.

A pressure gauge 43 with a contact is arranged in the permeation side pipe 74, and it is also possible to control the opening / closing operation of the automatic opening / closing valves 62 and 63 by a controller (not shown) based on a signal from the pressure gauge 43. is there.

[0016]

【Example】

Example 1 In FIG. 1, the conductivity was 250 μS / cm, pH as a stock solution.
= 6.5 of well water was 150m ³ use. As the separation membrane module 3, an aromatic polyamide-based composite membrane having an operating pressure of 7.5 kgf / cm ² , a permeated water amount of 6.5 m ³ / day, and a rejection of 99.5% in a 0.05% aqueous NaCl solution at a temperature of 25 ° C. A spiral module was used.

At a feed water flow rate of 30 l / min,
The pressure control valve 61 is adjusted so that the pressure gauge 41 on the supply side displays 7.8 kgf / cm ² and the pressure gauge 42 on the non-permeation side displays 7.2 kgf / cm ² , and the automatic on-off valve 62 is opened to open the separation membrane. When the operation is performed by opening the permeation side 32 of the module 3 to the atmosphere and closing the automatic on-off valve 63, the flow rate is 4.5 liter / mi.
n, permeated water having a conductivity of 11.3 μS / cm was obtained.

Thereafter, the automatic on-off valve 62 was set to be closed for 0.5 minute for every 4.5 minutes of operation. Further, when the pressure gauge 43 with the contact on the permeation side detects a value of 1 kgf / cm ² or more, the automatic opening / closing valve 63 is opened by the detection signal and the permeated water is returned to the suction pipe 71 of the pressurizing pump 2. did. After operating for 10 hours under the set conditions, the permeated water had a flow rate of 4.5 L / min and an electric conductivity of 1.
1.3 μS / cm could be almost maintained.

Comparative Example 1 An operation was performed under the same conditions as in Example 1 except that the automatic on-off valve 63 was kept closed regardless of the detection value of the pressure gauge 43 with a contact. As a result, the flow rate of the permeated water increased to 9.5 liter / min, and the conductivity increased to 95.3 μS / cm. At the moment when the automatic on-off valve 62 closes and reopens 0.5 minutes later, since the pressure gauge 43 with a contact point showed a value of 7.5 kgf / cm ² , these phenomena of the increase in the permeated water flow rate and the conductivity were as follows. This is probably due to film breakage due to peeling.

Comparative Example 2 Regardless of the detection value of the pressure gauge 43 with a contact, the automatic on-off valve 63 is kept closed, and the pressurizing pump 2 is operated for 4.5 minutes in synchronization with the movement of the automatic on-off valve 62. The operation was performed under the same conditions as in Example 1 except that the operation was stopped for 0.5 minute. As a result, the flow rate of the permeated water slightly increased to 4.9 liter / min, and the conductivity increased to 25.1 μS / cm. At the moment when the pressurizing pump 2 was stopped, the pressure gauge 43 with the contact point showed a value of 7.4 kgf / cm ² due to the residual pressure on the supply side 31. It seems to be.

Example 2 After operating for 10 hours in Example 1, the total amount of permeated water was measured to be 2,430 liters.

Comparative Example 3 In Example 1, the pressurizing pump 2 was operated for 4.5 minutes while the automatic on-off valve 63 was closed, then stopped for 0.5 minutes, and the pressure gauge 41 was set to 0.5 kgf / cm ^2. After waiting for the following drop, the automatic on-off valve 62 was closed. When the pressure pump 2 is started again, the automatic opening / closing valve 62 is opened at the same time, and when the pressure gauge 41 is stabilized at 7.8 kgf / cm ² , the pressure pump 2
Was started and stopped at the above intervals. After the operation for 4.5 minutes, an average of 5.2 minutes was required until the operation for the next 4.5 minutes was started. As a result of performing such an intermittent operation for 10 hours and measuring the total amount of permeated water, 2
It was 330 liters. The conductivity of the permeated water was 11.5 μS / cm on average.

As described above, if the automatic on-off valve 63 is kept closed, it is necessary to perform considerably more troublesome operation than in the first embodiment to obtain the same level of permeate as in the first embodiment.
Moreover, it was clear that the amount of permeated water obtained was lower than that of Example 1.

[0024]

Since the liquid separation apparatus of the present invention has the above-described structure, in a continuous liquid concentration or fresh water production operation using a separation membrane module, an intermittent opening / closing operation is performed in a permeate pipe route. However, a stable permeate can be obtained efficiently. In addition, since the liquid can be distributed directly to individual containers from the permeation side, there is no need to install a dedicated permeate tank in the present apparatus, and space can be saved.

[Brief description of the drawings]

FIG. 1 is a flow chart of a liquid by a liquid separation device according to an embodiment.

FIG. 2 is a flow chart of a liquid by a conventional liquid separation device.

FIG. 3 is a flow chart of a liquid by another conventional liquid separation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Undiluted solution tank 2 Pressure pump 3 Separation membrane module 41, 42, 43 Pressure gauge 5 Flow meter 61, 62, 63 Automatic opening / closing valve 71 Suction piping 74 Permeation piping 75 Return piping 76 Extraction piping 8 Check valve

Claims (4)

[Claims] An apparatus for separating a liquid using a separation membrane module, wherein a pipe path on a permeation side of the separation membrane is branched into a take-out pipe for taking out a permeate and a return pipe circulating to a stock solution supply side of the separation membrane. A liquid separation device, comprising: 2. The pump according to claim 1, further comprising a pump for supplying the undiluted liquid to the undiluted liquid supply side pipe path, wherein a connection position between the return pipe and the undiluted liquid supply side pipe path is a suction side of the pump. The liquid separation device as described in the above. 3. The liquid separating apparatus according to claim 1, wherein an opening / closing valve is disposed in each of the take-out pipe and the return pipe. 4. A flow meter and / or a pressure gauge is further provided in a pipe line on the permeation side, and a control device is provided for controlling the opening / closing operation of each of said opening / closing valves in accordance with a detected value of these instruments. 4. The liquid separation device according to 3.