JPS5948122B2 - Reverse osmosis concentration method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reverse osmosis concentration method and apparatus in which a liquid to be concentrated is pressurized and separated into a concentrated liquid and a permeated liquid using a reverse osmosis apparatus.

Generally, in reverse osmosis concentrators, the higher the pressure of the liquid to be concentrated and the more severe the turbulence on the surface of the reverse osmosis membrane, the more permeate can be obtained.

On the other hand, as the concentration of the liquid to be concentrated, that is, the osmotic pressure increases, the permeate decreases.

Therefore, in the case of a liquid to be concentrated with a high concentration, in other words, a high osmotic pressure, it is impossible to reach a predetermined concentration ratio by passing it through the reverse osmosis device once, and it is necessary to pass it repeatedly.
It is necessary to gradually increase the concentration ratio.

This holds true even for a liquid to be concentrated with a low concentration, as the concentration ratio increases.

By the way, as mentioned above, conventional methods for concentrating a liquid to be concentrated by repeatedly passing it through a reverse osmosis device having a reverse osmosis membrane include a continuous pressurized circulation method and a batch method.

FIG. 1 is a system diagram showing a conventional reverse osmosis concentrator using a continuous pressurized circulation system.

In the figure, the suction side of a circulation pump 4 is connected via a pipe 3 to the terminal end side of a concentrated liquid supply pipe 2 having a pressure pump 1 in the middle, that is, to the discharge side of the pressure pump 1 .

The inlet side of a reverse osmosis device 7 having a permeated liquid outlet pipe 6 is connected to the discharge side of the circulation pump 4 via a conduit 5, and the outlet side of the reverse osmosis device 7 and the conduit 3 are connected to each other through a conduit 5. They are connected via line 8.

Thereby, the circulation pump 4 and the reverse osmosis device 7 are connected to the pipe line 3. 5. 8, they are connected in a closed loop.

One end of a concentrate extraction pipeline 9 is connected to the middle of the pipeline 8, a back pressure valve 10 is provided in the middle of the concentrate extraction pipeline 9, and the other end of the pipeline 9 is connected to a concentrated liquid extraction pipeline 9. Liquid storage tank 1
The opening has also been extended to the inside.

The reverse osmosis device 7 is of a normal type and has a reverse osmosis membrane inside.

In such a configuration, the liquid to be concentrated led to the pipe line 2 is pressurized by the pressurizing pump 1, and is supplied to the suction side of the circulation pump 4 via the pipe line 3 that constitutes a part of the closed loop pipe line. The permeate is further pressurized by the circulation pump 4 and guided to the reverse osmosis device 7, where it is concentrated, and the permeate is discharged from the permeate outlet pipe 6, while the concentrated liquid remaining in the reverse osmosis device 7 is is discharged into conduit 8.

At this time, the pressure at the inlet of the reverse osmosis device 7 (hereinafter simply referred to as inlet pressure) is usually preferably 50 to 5 Qkg/cm''.

Since the permeate flow rate of the reverse osmosis device 7 depends on the pressure, it is desirable that the pressure loss inside the reverse osmosis device 7 is small, but as mentioned above, there is a limit due to the influence of turbulence, and it is usually A pressure loss of 20-30 kg/cm' occurs.

Therefore, the pressure in the portion leading to the pipe line 8 (hereinafter simply referred to as outlet pressure) is 30 to 40 kg/cm''.

A small portion of the concentrate at this outlet pressure state is removed by the back pressure valve 1
0 to the concentrated liquid storage tank 11, most of it is pressurized again to the inlet pressure by the circulation pump 4 and concentrated repeatedly.

Due to this circulation, the concentration of the liquid in the pipe line 8 and the reverse osmosis device 7 will be reduced to approximately An equilibrium state is reached in the operating state of the circulation pump 4 when the flow rate becomes constant, and the concentration operation can be continued continuously thereafter.

In this continuous pressurized circulation system, the closed loop pipe line consisting of the pipe line 3°5.8 is not opened to the atmosphere, so the outlet pressure can be used without releasing it to the atmosphere.
It has the feature that the operating power can be reduced to 50% or less compared to the batch method described later.

However, when the equilibrium state is reached, the concentration of the liquid flowing inside the reverse osmosis device 7 is extremely high compared to before concentration, so the flow rate of the permeated liquid becomes as shown by curve A in FIG. As the operating time elapses, it suddenly decreases at the position where the equilibrium state is reached.

Therefore, in order to obtain the necessary amount of concentrated liquid, this method has the disadvantage that the scale of the reverse osmosis device 7 must be larger than that of the batch method described later.

Second. @Yo, this is a system diagram of a reverse osmosis concentrator using a conventional batch method.

In this figure, the same or equivalent components as in FIG. 1 are designated by the same reference numerals.

The liquid to be concentrated supply pipe 2 has its terminal end opened in a concentration tank 12 which is open to the atmosphere, and a suction side pipe 3 of a circulation pump 4 is connected to the lower part of the concentration tank 12 .

The discharge side pipe line 5 of this circulation pump 4 includes a permeated liquid outlet pipe 6.
A reverse osmosis device 7 having the
The other end of this pipe line 8 is open to the concentration tank 12 .

In addition, a transfer pump 1 is provided in the lower part of the concentration tank 12.
3 is connected to one end of a concentrate extraction pipe 9, and the other end of this pipe 9 is opened to a concentrate storage tank 11.

In such a configuration, a fixed amount of the liquid to be concentrated is supplied from the liquid to be concentrated supply line 12 to the concentration tank 12 .

The liquid to be concentrated is pressurized by the circulation pump 4 and guided to the reverse osmosis device 7, and the liquid slightly concentrated by the reverse osmosis device 7 is returned to the concentration tank 12 via the pipe 8 and circulated again. The pump 4 sends it through the above-mentioned route and the concentration is repeated.

As a result, when the liquid in the concentration tank 12 reaches a predetermined concentration, the circulation pump 4 is stopped, the transfer pump 13 is activated, and the liquid in the concentration tank 12 is transferred to the concentrated liquid storage tank 11 via the extraction pipe 9. be done.

When this transfer is completed, a predetermined amount of the liquid to be concentrated is again supplied from the supply pipe 2, concentration is carried out in the same manner as described above, and a predetermined amount of the concentrate is taken out in portions (batchwise).

In this system as well, the inlet □ pressure and outlet pressure are the same as described above.

The permeate flow rate in this batch system is curve B in Figure 5.
As shown in Figure 2, although it gradually decreases with the passage of operating time, the average permeate volume is superior to that of the continuous pressurized circulation system.

However, this method has the disadvantage that the efficiency of operating power is poor because the outlet pressure is released to the atmosphere, and that it requires more than twice as much power as the continuous pressurized circulation method.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the drawbacks of the prior art and provide a reverse osmosis concentration method and apparatus thereof that require low operating power without reducing the average flow rate of the permeate.

The present invention was developed by focusing on the fact that the disadvantage of continuous pressurized circulation system is that a highly concentrated liquid flows inside the reverse osmosis device in an equilibrium state. The above objective is achieved by providing a flow path switching device that switches between the flow in the closed loop pipe and the flow into the concentrate extraction pipe, and by intermittently extracting a high concentration liquid and replacing it with a low concentration liquid. It is something to do.

Embodiments of the present invention will be described below based on the drawings.

Here, the same components as those in the conventional example are denoted by the same reference numerals to simplify the explanation.

FIG. 31 shows the first embodiment of the present invention. In FIG. 3, the terminal end of the concentrated liquid supply pipe 2 having the pressurizing pump 1 in the middle is connected to the suction side pipe 3 of the circulation pump 4. is,
The discharge side pipe line 5 of this circulation pump 4 includes a permeated liquid outlet pipe 6.
One end of a conduit 8 is connected through a reverse osmosis device 7 having a reverse osmosis device 7, and the other end of this conduit 8 is connected to the conduit 3.

As a result, conduit 3. 5. 8 constitutes a closed loop conduit that is not open to the atmosphere.

One end of a concentrate extraction pipe 9 is connected to the middle of the pipe 8 via a three-way switching valve 14 , and the other end of the pipe 9 is opened to a concentrate storage tank 11 .

The three-way switching valve 14 allows the pipe line 8 to flow and closes the take-out pipe line 9, and also blocks the flow downstream from the connection part of the take-out pipe line 9 of the pipe line 8 and connects the pipe line 8 and the take-out pipe It is possible to switch between the state of communication with the line 9.

Further, in the middle of the pipe line 8, a three-way switching valve 15 is provided at an intermediate position between the connection part with the extraction pipe line 9 and the connection part with the pipe line 3.
One end of the bypass line 16 is connected through the bypass line 16, and the other end of the bypass line 16 is connected to the upstream side of the concentrated liquid supply line 2, bypassing the pressurizing pump 1.

The three-way switching valve 15 allows the pipe line 8 to communicate with the bypass pipe line 16 and closes the bypass pipe line 16, and the pipe line 8 upstream from the connection part with the bypass pipe line 16 to be closed and connects the bypass pipe line 16 and the pipe line 8. It is possible to switch between the state in which the

Further, these three-way switching valves 14 and 15 constitute a flow path switching device.

Note that the circulation pump 4 is a pump having a flow rate several steps larger than that of the pressure pump 1, for example, about 5 to 10 times.

Next, the operation of this embodiment will be explained separately for the concentration state and the replacement state.

In the concentrated state, each of the three-way switching valves 14 and 15 communicates with the pipe line 8, and the liquid to be concentrated is supplied from the supply pipe line 2 to the circulation pump 4 via the pressurizing pump 1. .

The liquid to be concentrated is concentrated by discharging the permeated liquid through the permeated liquid outlet pipe 9 by the reverse osmosis device 7, and is returned to the circulation pump 4 via the pipes 8 and 3, and the circulation is repeated again by the above-mentioned route.

At this time, the liquid to be concentrated corresponding to the outflow of the permeate is supplied from the supply pipe 2, but at the beginning of this concentration, the liquid concentration in the closed loop pipe is low, so the amount of permeate flowing out is large. It gradually decreases (see curves C1, C2, etc. in FIG. 5).

In this manner, circulation is repeated until the liquid in the closed loop pipe reaches a predetermined concentration, and when the predetermined concentration is reached, the concentrated liquid is replaced by the following operation.

In the replacement state, the three-way switching valves 14 and 15 are operated to connect the pipe line 8 and the extraction pipe line 9, and also to make the pipe line 16 and the pipe line 8 communicate with each other.

At this time, it is preferable to stop the pressure pump 1 so as not to apply excessive pressure to the reverse osmosis device 7.

When the three-way switching valve 14.15 is switched to the above-mentioned state,
The liquid to be concentrated in the supply pipe 2 is sent to the reverse osmosis device 7 by the action of the circulation pump 4 via the bypass pipe 16, the pipe 8 and the suction side pipe 3, bypassing the pressurizing pump 1, and further Invades pipe 8.

As a result, conduit 8. 3. 5. The concentrated liquid accumulated in the circulation pump 4, the reverse osmosis device 7, and the pipe line 8 is pushed by the liquid to be concentrated and is sequentially sent to the extraction pipe line 9 via the three-way switching valve 14, and is transferred to the concentrated liquid storage tank 11. is discharged.

When the discharge of this concentrated liquid is completed, each three-way switching valve 14
．． 15 are operated to connect the respective conduits 8, and the above-mentioned concentration action is started.

In this way, the concentrated state and the replacement state are repeated and the concentrated liquid is taken out intermittently.

As can be seen from Fig. 5, the period of this intermittent extraction is as follows:
The period is about a fraction of that of the conventional batch method, and it is carried out using only a large range of permeate flow rate.

According to this embodiment, the three-way switching valve 1 as a flow path switching device
As the highly concentrated liquid in the closed loop system can be taken out intermittently by the operation in 4.15, it is possible to prevent a sudden drop in the flow rate of the permeate, which is a drawback of the conventional continuous pressurized circulation system. 7 can be prevented from increasing in size.

That is, in this example, the curves C1, C2... in FIG.
As shown in Figure 2, it is desirable to stop the concentration action, complete the cycle, and take out the concentrated liquid before the permeate flow rate suddenly decreases.

In addition, since the three-way switching valve 15 is switched and the liquid to be concentrated is supplied from the bypass pipe 16 via the large-capacity circulation pump 4, the reverse osmosis device 7 is not adversely affected.
High concentration liquid can be replaced with low concentration liquid in an extremely short time.

Furthermore, as a comprehensive effect of each of the above-mentioned effects, it becomes a system that combines only the advantages of the conventional continuous pressurized circulation system and the batch system, and can be a system that is low in equipment cost and operating cost.

Next, FIG. 4 shows a second embodiment of the present invention, which differs from the first embodiment in that there is a In addition to the provision of the tank 17, a pressure release line 19 having a pressure release valve 18 in the middle and communicating the middle of the line 8, that is, between the intermediate tank 17 and the reverse osmosis device 7, and the extraction line 9 is provided. This is what we have set up.

According to this embodiment, the following effects can be added in addition to the effects of the first embodiment.

That is, the intermediate tank 17 increases the amount of liquid held in the closed loop system, and as a result, the frequency of replacing high concentration liquid with low concentration liquid is reduced, which saves wasted time required for replacement and increases concentration efficiency. .

Further, the shorter the time required for the replacement, the better, and this can be achieved by a pressure release line 19 having a pressure release valve 18.

That is, in order to shorten the replacement time, it is better not to stop or restart the pressurizing pump 1 and the circulation pump 4 during the transition from the concentration state to the replacement state and vice versa.

However, in the embodiment shown in FIG. 3, since the inlet pressure and outlet pressure change rapidly when switching between states, there is a risk of destroying the reverse osmosis membrane of the reverse osmosis device 7, and the pressure pump 1
Only needs to be stopped once.

In contrast, if the pressure release valve 1B and the pressure release pipe 19 are provided as in this embodiment, and the pressure release valve 18 is opened before the transition from the concentration state to the replacement state, the pressure in the system is reduced. Both the pressurizing pump 1 and the circulation pump 4 may be operated continuously, and the time required for replacement can be shortened.

Further, when transitioning from the substitution state to the concentration state, closing the pressure release valve 18 after the transition is completed is effective in eliminating sudden pressure fluctuations.

Further, the diameters of the pressure release valve 18 and the pressure release conduit 19 may be extremely small as long as they have the effect of lowering the pressure.

In each of the above embodiments, the circulation pump 4 was installed between the connection part of the supply pipe line 2 and the reverse osmosis device 7, but the installation location of the circulation pump 4 is not limited to this, and for example, the place where the circulation pump 4 is installed is not limited to this. It may also be provided at other locations in the closed loop line, such as intermediate the connection between line 16 and supply line 2.

That is, instead of further pressurizing the concentrated liquid pressurized by the pressure pump 1 by the circulation pump 4, the discharge flow of the pressure pump 1 and the discharge flow of the circulation pump 4 are combined and the reverse osmosis device 7
, and the return from the reverse osmosis device 7 may be guided to the circulation pump 4.

Furthermore, the bypass pipe line 16 is not limited to one provided branching off from the supply pipe line 2, and may be a pipe line that can introduce the liquid to be concentrated into a system separate from the supply pipe line 2. It is sufficient if the liquid to be concentrated at a low concentration can be introduced without going through the pressurizing pump 1.

Furthermore, two three-way switching valves 14.1 are used as flow switching devices.
5 was used, but other configurations were used, for example, a configuration in which the three-way switching valve 14 was left as is and the three-way switching valve 15 was provided as a normal on-off valve in the middle of the bypass pipe 16, or the three-way switching valve 14 and 15 were not used. Using three on-off valves, each on-off valve is provided in the middle of the outlet pipe line 9, the bypass line 16, and the connection part of the line 8 with the outlet line 9 and the connection part with the bypass line 16. In the enrichment state, only the on-off valve of the pipe line 8 is open and the others are closed, and in the replacement state, the reverse is possible.Although this function can also be achieved by other known methods, it is not possible to use a three-way switching valve. It has the advantage of being inexpensive if used.

Furthermore, in the second embodiment, the installation position of the intermediate tank 17 and the connection position of the pipe line 8 and the pressure relief pipe line 19 are as follows.
The position is not limited to the one shown in the figure, but may be anywhere along the closed loop conduit.

Further, the pressure release pipe 19 does not need to merge with the extraction pipe line 9.

Furthermore, by using the pressurizing pump 1 in Fig. 4 as a fixed-rate pump, a characteristic occurs in which the pressure within the system increases as the concentration within the system increases, thereby keeping the amount of permeate liquid constant. It can be a device.

In addition, the three-way switching valve 14.15 and the pressure release valve 18 are automatic valves, and a pressure detection device is provided in the pipeline 8, so that each valve 14.15.18 is automatically operated by this pressure detection device. Then, when the concentration in the system reaches a certain level, the high concentration liquid can be automatically replaced with the low concentration liquid, resulting in an apparatus that can be operated continuously without requiring manual labor.

As described above, according to the present invention, there is an effect that it is possible to provide a reverse osmosis concentration method and an apparatus thereof, which can perform a large amount of concentration treatment using a small-scale device with low operating power.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a conventional reverse osmosis concentrator using a continuous pressurized circulation system. FIG. 2 is a system diagram showing a conventional batch-type reverse osmosis concentration device, FIG. 3 is a system diagram showing a first embodiment of the reverse osmosis concentration device according to the present invention, and FIG. 4 is a system diagram showing a second embodiment of the present invention. FIG. 5, a system diagram showing an example, is a diagram showing the relationship between operating time and permeate flow rate in the conventional device and the device of the present invention. 1... Pressure pump, 2... Concentrated liquid supply pipe line, 3, 5. 8...Pipe line constituting a closed loop pipe line, 4...Circulation pump, 7...
- Reverse osmosis device, 9... Concentrate extraction pipe, 14.
15... Three-way switching valve as a flow path switching device, 1
6...Bypass pipe line, 17...Intermediate tank, 18...Pressure release valve, 19...
Pressure relief line.

Claims (1)

[Scope of Claims] 1. A system that includes a reverse osmosis device and a circulation pump, and supplies the liquid to be concentrated to a closed-loop pipeline that is not open to the outside air through a pressurizing pump, while the liquid to be concentrated is reversely reversed by the circulation pump. The concentrated liquid is circulated through the closed loop pipe through the infiltration device to be concentrated, and when the circulating liquid to be concentrated reaches a predetermined concentration, the concentrated liquid extraction pipe is opened to take out the concentrated liquid from the closed loop pipe. The closed loop pipe downstream of this extraction pipe is closed, the pressure pump is bypassed, and a new liquid to be concentrated is supplied to the suction side of the circulation pump, and this new liquid to be concentrated is passed through the circulation pump. The concentrated liquid remaining in the closed loop pipe is discharged to the extraction pipe side by pressure feeding and collected, and this series of operations is repeated to intermittently discharge the concentrated liquid to the outside. Reverse osmosis concentration method. 2 The reverse osmosis device and the circulation pump are connected in a closed loop through a pipe without being exposed to the atmosphere, and a liquid to be concentrated supply pipe and a concentrate extraction pipe with a pressurizing pump in the middle are connected to this closed loop pipe. In the reverse osmosis concentrator configured to be connected, a bypass pipe is provided which bypasses the pressure pump and is connected to the suction side of the circulation pump of the closed loop pipe, and the bypass pipe is connected to the closed loop pipe on the suction side of the circulation pump. A state in which the flow from the bypass pipe and the flow to the concentrate extraction pipe is blocked and a circulating flow in the closed loop pipe is allowed, and a state in which the flow from the bypass pipe and the flow to the concentrate removal pipe is allowed and the circulation flow in the closed loop pipe is allowed. A reverse osmosis concentrator, comprising a flow path switching device capable of switching between a state in which flow downstream from a connection part of a concentrate extraction pipe is blocked. 3. The reverse osmosis concentrator according to claim 2, characterized in that an intermediate tank is provided in the middle of the closed loop pipeline. 4 In claim 2 or 3,
A reverse osmosis concentrator characterized in that a pressure release line having a pressure release valve is connected in the middle of the closed loop line.