JP2019202253A - Reverse osmosis separation method and reverse osmosis separation device - Google Patents

Abstract

To provide a reverse osmosis separation method and a reverse osmosis separation device that can keep an osmotic pressure difference small between a high osmotic pressure liquid and a permeation liquid flowing with a reverse osmotic membrane in between at an inlet and an outlet of a reverse osmosis membrane module through which the high osmotic pressure liquid passes and can control variations in the osmotic pressure difference between the high osmotic pressure liquid and the permeation liquid.SOLUTION: A reverse osmosis separation device comprises multiple stages of reverse osmosis membrane modules 10 each having an undiluted solution side channel 12 and a permeation liquid side channel 13 which are in contact with each other with a reverse osmosis membrane 11 in between. One pipe 2a for supplying a high pressure undiluted solution Hi pressurized by a pressurization pump 4 is connected to the inlet side of the undiluted solution side channel 12 of the reverse osmosis membrane module 10, and another pipe 2b for directly supplying an undiluted solution H is connected to the outlet side of a permeation liquid side channel 13 of the reverse osmosis membrane module 10 so that the undiluted solution H flows counter to a flow of the high pressure undiluted solution Hi supplied being pressurized to the inlet side of the undiluted solution side channel 12. A flowmeter 5b and a flow adjusting valve 6 for adjusting a flow rate of the undiluted solution H supplied to the outlet side of the permeation liquid side channel 13 are arranged in the other pipe 2b.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a reverse osmosis separation method and reverse osmosis separation used to make water from high-concentration high osmotic pressure liquids such as seawater, to separate water and impurities, and to concentrate fruit juice and chemicals. It relates to the device.

  The reverse osmosis separation method described above is a treatment using a reverse osmosis membrane. For example, when water is made from seawater, which is a high concentration high osmotic pressure solution, one flow path in contact with the reverse osmosis membrane in between. The pure water is obtained by flowing seawater to which the pressure equal to or higher than the osmotic pressure of seawater is passed and allowing only the water to permeate through the other channel.

  In such a reverse osmosis separation method using a reverse osmosis membrane, a high concentration high osmotic pressure solution introduced into one flow path of the reverse osmosis membrane is concentrated toward the outlet of one flow path. Higher concentration.

  In other words, on the outlet side of one flow path of the reverse osmosis membrane, the difference in osmotic pressure between the high osmotic pressure liquid and the permeate flowing through the other flow path of the reverse osmosis membrane becomes large, and the permeation speed decreases. .

Conventionally, Patent Document 1 discloses a reverse osmosis separation method in which measures for dealing with such a decrease in permeation rate are taken.
In the reverse osmosis separation method described in Patent Document 1, first, a high-concentration high osmotic pressure liquid is divided into two, and one high osmotic pressure liquid is pressurized with a pressurizing pump, and the first stage reverse osmosis is performed. While supplying to the inlet side of one flow path in the membrane module, the other high osmotic pressure liquid is supplied to the outlet side of the other flow path in the first-stage reverse osmosis membrane module as it is, Get.

  Next, the low-concentration permeate obtained in this step is divided into two, one is pressurized by a pressure pump and supplied to the inlet side of one flow path in the second-stage reverse osmosis membrane module, and the other Is supplied to the outlet side of the other channel in the second-stage reverse osmosis membrane module as it is to obtain a permeate having a further low concentration.

  Thereafter, the above reverse osmosis separation treatment is repeated for the low-concentration permeate obtained with the reverse osmosis membrane module, and all the low-concentration permeate obtained with the reverse osmosis membrane module in the previous stage is subjected to a pressure pump. Pressure is applied and supplied to the inlet side of one of the flow paths in the reverse osmosis membrane module in the final stage to obtain a further low concentration permeate.

JP 2003-144855 A

  However, in the conventional reverse osmosis separation method described above, the osmotic pressure difference between the high osmotic pressure liquid and the permeate flowing through the other flow path of the reverse osmosis membrane is reduced at the outlet of one flow path in the reverse osmosis membrane module. However, there is a problem that the osmotic pressure difference between the high osmotic pressure liquid and the permeated liquid flowing through the other flow path of the reverse osmosis membrane cannot be controlled. It was an issue.

  The present disclosure has been made by paying attention to the above-described problem, and a high osmotic pressure liquid and a permeate flowing between the reverse osmosis membranes at the inlet and the outlet of the reverse osmosis membrane module through which the high osmotic pressure liquid passes. An object of the present invention is to provide a reverse osmosis separation method and a reverse osmosis separation device capable of controlling the osmotic pressure difference between the high osmotic pressure liquid and the permeate to move up and down while keeping the osmotic pressure difference between Yes.

  According to a first aspect of the present disclosure, a reverse osmosis membrane module having one channel and another channel that are in contact with each other with a reverse osmosis membrane interposed therebetween is arranged in a plurality of stages, and a plurality of stages are formed in a high concentration high osmotic pressure liquid. A reverse osmosis separation method for obtaining a permeate by passing through the reverse osmosis membrane module disposed in the reverse osmosis membrane module, wherein the reverse osmosis membrane module disposed in a plurality of stages has a high concentration and high osmosis on the inlet side of the one channel. The high osmotic pressure liquid supplied by pressurizing the pressure liquid with a pump, supplying the high osmotic pressure liquid to the outlet side of the other flow path, and applying pressure to the inlet side of the one flow path And the flow of the high osmotic pressure liquid supplied to the outlet side of the other flow path are opposed to each other, and the supply of the high osmotic pressure liquid to the outlet side of the other flow path is The configuration is performed while adjusting the flow rate of the liquid.

  In the second aspect of the present disclosure, the high osmotic pressure liquid supplied to the outlet side of the other channel is the high osmotic pressure discharged from the one channel in the reverse osmosis membrane module in the subsequent stage. The liquid concentrate concentrate is used.

  According to a third aspect of the present disclosure, energy is recovered from the concentrated stock solution of the high osmotic pressure liquid discharged from the one flow path in the reverse osmosis membrane module, and the other flow in the reverse osmosis membrane module in the subsequent stage is recovered. It is set as the structure given to the diluted stock solution discharged | emitted from a path.

  On the other hand, the fourth aspect of the present disclosure includes a plurality of reverse osmosis membrane modules each having one channel and the other channel in contact with a reverse osmosis membrane, and the one channel in the reverse osmosis membrane module One of the pipes is supplied to the inlet side of the reverse osmosis membrane module while being supplied with a high concentration high osmotic pressure liquid pressurized by a pump. The other pipe for supplying the high-concentration high osmotic pressure liquid as it is is connected to the other pipe so as to face the flow of the high osmotic pressure liquid supplied by being pressurized to the inlet side of the other pipe. A flow meter for adjusting the flow rate of the high osmotic pressure liquid supplied to the outlet side of the flow path and a flow rate adjusting valve are arranged.

  In the reverse osmosis separation method according to the first aspect of the present disclosure and the reverse osmosis separation apparatus according to the fourth aspect, a high concentration high osmotic pressure liquid is applied to the inlet side of one flow path of the reverse osmosis membrane module by a pump. Since the high osmotic pressure liquid is supplied as it is to the outlet side of the other flow path so as to face the flow of the pressurized high osmotic pressure liquid in one flow path, The osmotic pressure of the channel increases, and the osmotic pressure difference with one channel decreases, and as a result, a decrease in permeation rate can be avoided.

  In the reverse osmosis separation method according to the first aspect of the present disclosure and the reverse osmosis separation apparatus according to the fourth aspect, the flow rate of the high osmotic pressure liquid supplied to the outlet side of the other channel is adjusted. Therefore, it is possible to control the vertical movement of the osmotic pressure difference between the pressurized high osmotic pressure liquid flowing in one flow path and the permeated liquid flowing in the other flow path.

  In the reverse osmosis separation method according to the second aspect of the present disclosure, the high osmotic pressure liquid supplied to the outlet side of the other channel in the reverse osmosis membrane module is discharged from one channel in the subsequent reverse osmosis membrane module. Since the concentrated osmotic solution of the high osmotic pressure liquid is used, the high osmotic pressure liquid is circulated between the adjacent reverse osmosis membrane modules, and as a result, the reverse osmosis membrane module is kept clean. Become.

  In the reverse osmosis separation method according to the third aspect of the present disclosure, the energy of the concentrated concentrate of the high osmotic pressure liquid discharged from one flow path of the reverse osmosis membrane module is transferred to the other flow of the subsequent reverse osmosis membrane module. Since it is given to the diluted stock solution discharged from the passage, the energy consumption can be reduced.

  According to the reverse osmosis separation method according to the present disclosure, at the inlet and outlet of the reverse osmosis membrane module through which the high osmotic pressure liquid passes, the osmotic pressure difference between the high osmotic pressure liquid and the permeate flowing between the reverse osmosis membranes is reduced. In addition, an excellent effect is brought about in that it is possible to control the vertical movement of the osmotic pressure difference between the high osmotic pressure liquid and the permeated liquid.

It is explanatory drawing which shows typically the reverse osmosis separation apparatus which concerns on one Embodiment of this indication. It is an expanded sectional explanatory view showing the reverse osmosis membrane module of FIG. It is a graph which shows the change of the osmotic pressure difference from the flow-path inlet side to the flow-path exit side in the reverse osmosis membrane module of FIG. It is explanatory drawing which shows typically the reverse osmosis separation apparatus which concerns on other embodiment of this indication. It is explanatory drawing which shows typically the reverse osmosis separation apparatus which concerns on other embodiment of this indication.

Hereinafter, a reverse osmosis separation method and a reverse osmosis separation device according to the present disclosure will be described with reference to the drawings.
1 and 2 show an embodiment of a reverse osmosis separation device according to the present disclosure.

  As shown in FIG. 1, this reverse osmosis separation device 1 is formed by combining a plurality of reverse osmosis membrane modules 10 having reverse osmosis membranes 11 in multiple stages through a number of pipes to be described later. Has a stock solution side flow path (one flow path) 12 for flowing a high osmotic pressure stock solution in contact with the reverse osmosis membrane 11 and a permeate side flow path (the other flow path) 13 for flowing a permeate. Yes.

  In this reverse osmosis separation device 1, a pipe 2 for introducing a stock solution having the highest concentration and a high osmotic pressure with a pressure pump 3 is introduced into the pipes 2 a and 2 b before the reverse osmosis membrane module 10 in the first stage. As shown in FIG. 2, one of the pipes 2a is connected to the inlet side (the lower side in the drawing) of the stock solution side channel 12 in the first-stage reverse osmosis membrane module 10, and the other pipe 2b is connected to the first stage. The reverse osmosis membrane module 10 of the eye is connected to the outlet side (upper side in the drawing) of the permeate side flow path 13.

  A pressure pump 4 and a flow meter 5a are arranged in one of the pipes 2a, and a high-pressure undiluted solution Hi is introduced from the inlet side of the undiluted solution side channel 12 in the first-stage reverse osmosis membrane module 10 so as to be introduced. It has become.

  The other pipe 2b is provided with a flow meter 5b and a flow rate adjusting valve 6 so as to adjust the flow rate of the stock solution H introduced from the outlet side into the permeate side flow path 13 of the first-stage reverse osmosis membrane module 10. It has become.

  A pipe 22 through which the diluted stock solution L flows is connected to the inlet side of the permeate-side flow path 13 in the first-stage reverse osmosis membrane module 10, and this pipe 22 is connected to the second-stage reverse osmosis membrane module 10. The pipe 22a and 22b are branched to the front, and one pipe 22a is connected to the inlet side of the stock solution side channel 12 in the second-stage reverse osmosis membrane module 10, and the other pipe 22b is the second-stage reverse osmosis membrane module. 10 is connected to the outlet side of the permeate-side flow path 13.

  A pressure pump 24 and a flow meter 25a are also arranged in one of the pipes 2a branched from the pipe 22, and high-pressure dilution in which the pressure is increased with respect to the stock solution side flow path 12 in the second-stage reverse osmosis membrane module 10. The stock solution Li is introduced. Further, a flow meter 25b and a flow rate adjustment valve 26 are also arranged on the other pipe 22b branched from the pipe 22, so that the dilution introduced from the outlet side to the permeate side flow path 13 of the reverse osmosis membrane module 10 in the second stage. The flow rate of the stock solution L is adjusted.

  A pipe 32 through which the diluted stock solution L is further diluted is connected to the inlet side of the permeate-side flow path 13 in the second-stage reverse osmosis membrane module 10, and this pipe 32 is also connected to the third-stage reverse osmosis membrane. Before the membrane module 10, the pipes 32a and 32b are branched. One pipe 32a is connected to the inlet side of the stock solution side flow path 12 in the third-stage reverse osmosis membrane module 10, and the other pipe 32b is connected to the third stage. The reverse osmosis membrane module 10 is connected to the outlet side of the permeate side flow path 13.

  A pressure pump 34 and a flow meter 35a are also arranged in one of the pipes 32a branched from the pipe 32, and the high pressure is increased from the inlet side of the stock solution side flow path 12 in the third-stage reverse osmosis membrane module 10. The diluted stock solution Li is introduced. A flow meter 35b and a flow rate adjusting valve 36 are also arranged on the other pipe 32b branched from the pipe 32, so that the dilution introduced from the outlet side into the permeate side flow path 13 of the third-stage reverse osmosis membrane module 10 is performed. The flow rate of the stock solution L is adjusted.

  In this case, the energy recovery unit 8 is disposed in the one pipe 32 a connected to the third-stage reverse osmosis membrane module 10, and from the outlet side of the stock solution side flow path 12 in the first-stage reverse osmosis membrane module 10. Energy is recovered from the concentrated stock solution Ho that is discharged and flows through the discharge pipe 7.

  A pipe 42 is connected to the inlet side of the permeate side flow path 13 in the third-stage reverse osmosis membrane module 10 and the pressure of the diluted diluted stock solution L is increased by the pressurizing pump 44. 42 is connected to the inlet side of the stock solution side flow path 12 in the reverse osmosis membrane module 10 in the fourth stage.

A pipe 52 for discharging the permeated liquid Lo having a predetermined concentration is connected to the inlet side of the permeated liquid side flow path 13 of the fourth-stage reverse osmosis membrane module 10.
In addition, in order to obtain the permeated liquid Lo having a predetermined concentration, it is desirable to monitor the concentration at various portions of the multiple-stage reverse osmosis membrane module 10.

  In this embodiment, by connecting the outlet side of the stock solution side flow path 12 in the second-stage reverse osmosis membrane module 10 and the one pipe 2a branched from the pipe 2 by a return pipe 27, the second-stage reverse osmosis membrane module 10 is connected. The concentrated stock solution Ho discharged from the osmosis membrane module 10 is returned to the stock solution side flow path 12 of the first-stage reverse osmosis membrane module 10 for reuse. At this time, the booster pump 29 is disposed in the return pipe 27 so that the pressure of the concentrated stock solution Ho discharged from the second-stage reverse osmosis membrane module 10 is increased to the same level as that of the one pipe 2a.

  Similarly to the return pipe 27 and the booster pump 29, the outlet side of each stock solution side flow path 12 in the third and fourth stage reverse osmosis membrane modules 10 and one of the pipes 22a and 32a branched from the pipes 22 and 32 are connected. The return pipes 37 and 47 are connected to each other, and booster pumps 39 and 49 are arranged in the return pipes 37 and 47.

  As described above, in the reverse osmosis separation device 1, in the 1st to 3rd stage reverse osmosis membrane modules 10, a high concentration undiluted solution H is pressurized to the inlet side of the undiluted solution side channel 12 by the pressurizing pump 4, and the As shown in FIG. 3, the raw solution H is supplied as it is to the outlet side of the permeate side flow path 13 and the flow of the high-pressure raw solution Hi and the flow of the raw solution H are opposed to each other. The osmotic pressure of the permeate side channel 13 is increased so as to reduce the osmotic pressure difference between the stock solution side channel 12 side and the permeate side channel 13 side.

  Therefore, the reverse osmosis separation device 1 can avoid a decrease in permeation rate. In addition, in this reverse osmosis separation device 1, the flow rate of the stock solution H (diluted stock solution L) supplied to the outlet side of the permeate side flow path 13 is adjusted by the flow meters 5 b, 25 b, 35 b and the flow rate adjustment valve 6. Therefore, the osmotic pressure difference between the pressurized high-pressure stock solution Hi (high-pressure diluted stock solution Li) flowing through the stock-solution side channel 12 and the stock solution H (diluted stock solution L) flowing through the permeate-side channel 13 moves up and down. By controlling the osmotic pressure, the osmotic pressure difference can be kept constant.

Therefore, the reverse osmosis separation operation (reverse osmosis separation method) of the reverse osmosis separation device 1 described above will be described.
First, the high-concentration stock solution H pressurized by the pressurization pump 3 and introduced by the pipe 2 is branched into two, and the high-pressure stock solution Hi pressurized by the pressurization pump 4 of the one pipe 2a is one stage. It is introduced from the inlet side of the stock solution side channel 12 in the reverse osmosis membrane module 10 of the eye.

  The undiluted solution H that is branched and flows to the other pipe 2 b is introduced as it is from the outlet side of the permeate-side flow path 13 in the first-stage reverse osmosis membrane module 10, and the reverse osmosis pressure in the first-stage reverse osmosis membrane module 10. To obtain a diluted stock solution L.

  Next, the diluted stock solution L that flows out from the inlet side of the permeate-side flow path 13 in the first-stage reverse osmosis membrane module 10 and flows through the pipe 22 is branched into two, flows into one pipe 22a, and is supplied by the pressure pump 24. The pressurized high-pressure diluted stock solution Li is introduced from the inlet side of the stock solution-side flow path 12 in the second-stage reverse osmosis membrane module 10, and the diluted stock solution L branched and flowing to the other pipe 22b is used as it is. It is introduced from the outlet side of the permeate-side channel 13 in the reverse osmosis membrane module 10 and a diluted stock solution L is obtained by reverse osmosis pressure in the second-stage reverse osmosis membrane module 10.

  Thereafter, the third-stage reverse osmosis membrane module 10 is also processed in the same manner as the first-stage and second-stage reverse osmosis membrane modules 10, and the diluted stock solution L obtained from the third-stage reverse osmosis membrane module 10 is used. Is pressurized by the pressurizing pump 44 and supplied to the inlet side of the stock solution side flow path 12 in the final fourth-stage reverse osmosis membrane module 10.

  Then, the permeated liquid Lo having a predetermined concentration obtained by the reverse osmosis pressure in the fourth-stage reverse osmosis membrane module 10 is discharged through the pipe 52 connected to the inlet side of the permeate side flow path 13.

  FIG. 4 illustrates another embodiment of a reverse osmosis separation device according to the present disclosure.

  As shown in FIG. 4, this reverse osmosis separation device differs from the reverse osmosis separation device 1 according to the previous embodiment in that reverse osmosis adjacent to each other in the first to fourth reverse osmosis membrane modules 10. Between the membrane modules 10, 10, the stock solution H supplied to the outlet side of the permeate-side channel 13 in the upstream reverse osmosis membrane module 10 is transferred from the outlet side of the stock-solution side channel 12 in the subsequent reverse osmosis membrane module 10. By using the concentrated stock solution Ho to be discharged and from the concentrated stock solution Ho discharged from the outlet side of the stock solution side flow path 12 and flowing through the return pipes 27, 37, 47 by the energy recovery units 8, 28, 38, 48. The energy is collected and applied to the diluted stock solution L discharged from the inlet side of the permeate side flow path 13 and flowing through the route of A → energy recovery unit 8, 28, 38, 48 → B.

  In the reverse osmosis separation device according to this embodiment, the diluted stock solution L is circulated between the adjacent reverse osmosis membrane modules 10 and 10, and as a result, the reverse osmosis membrane modules 10 and 10 are in a clean state. Will be kept. In addition, energy consumption can be reduced.

FIG. 5 shows yet another embodiment of a reverse osmosis separation device according to the present disclosure.
The reverse osmosis separation device differs from the reverse osmosis separation device 1 according to the previous embodiment in that the reverse osmosis separation device 1 is discharged from the outlet side of each stock solution side channel 12 in the first to third-stage reverse osmosis membrane modules 10. In the first and second reverse osmosis membrane modules 10, the concentrated stock solution Ho flowing through the return pipes 7, 27, 47 is pressurized to the inlet side of each of the raw solution side flow paths 12 in the subsequent reverse osmosis membrane module 10. The diluted stock solution L discharged from the inlet side of each permeate side flow path 13 in the first to third reverse osmosis membrane modules 10 is supplied (discharged as it is in the third reverse osmosis membrane module 10). It is in a point that it is obtained as a diluted permeate.

  In the reverse osmosis separation device according to this embodiment, since the diluted stock solution L can be obtained as the diluted permeate from the first to third-stage reverse osmosis membrane modules 10, acquisition of the diluted permeate having a desired concentration can be performed. It becomes possible.

  The present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure.

DESCRIPTION OF SYMBOLS 1 Reverse osmosis separation apparatus 2a, 22a, 32a One piping 2b, 22b, 32b The other piping 3, 4, 24, 34, 44 Pressurization pump 5a, 5b, 25a, 25b, 35a, 35b Flowmeter 6 Flow control valve 8, 28, 38, 48 Energy recovery unit 10 Reverse osmosis membrane module 11 Reverse osmosis membrane 12 Stock solution side channel (one channel)
13 Permeate side channel (the other channel)
H Stock solution (high osmotic pressure solution)
Hi High pressure stock solution Ho Concentrated stock solution L Diluted stock solution (permeate)
Li High-pressure dilution stock solution

Claims (4)

A reverse osmosis membrane module having a plurality of stages of reverse osmosis membrane modules having one channel and the other channel in contact with a reverse osmosis membrane therebetween, and arranged in a plurality of stages in a high concentration high osmotic pressure solution. A reverse osmosis separation method for obtaining a permeate by passing,
In the reverse osmosis membrane module arranged in a plurality of stages,
A high concentration high osmotic pressure liquid is supplied to the inlet side of the one flow path by a pump, and the high osmotic pressure liquid is supplied to the outlet side of the other flow path to supply the one flow path. The flow of the high osmotic pressure liquid pressurized and supplied to the inlet side and the flow of the high osmotic pressure liquid supplied to the outlet side of the other flow path,
The reverse osmosis separation method in which the supply of the high osmotic pressure liquid to the outlet side of the other channel is performed while adjusting the flow rate of the high osmotic pressure liquid.   The concentrated solution of the high osmotic pressure liquid discharged from the one flow path in the subsequent reverse osmosis membrane module is used for the high osmotic pressure liquid supplied to the outlet side of the other flow path. 2. The reverse osmosis separation method according to 1.   Energy is recovered from the concentrated stock solution of the high osmotic pressure liquid discharged from the one flow path in the reverse osmosis membrane module and applied to the diluted stock solution discharged from the other flow path in the subsequent reverse osmosis membrane module. The reverse osmosis separation method according to claim 1 or 2. A plurality of reverse osmosis membrane modules having one channel and the other channel in contact with a reverse osmosis membrane in between,
On the inlet side of the one flow path in the reverse osmosis membrane module, one pipe connected to supply a high concentration high osmotic pressure liquid with a pump is connected,
In the reverse osmosis membrane module, on the outlet side of the other channel, high concentration and high osmosis so as to oppose the flow of the high osmotic pressure liquid supplied to the inlet side of the one channel. The other pipe that supplies the pressurized fluid is connected,
A reverse osmosis separation device in which a flow meter and a flow rate adjusting valve for adjusting a flow rate of the high osmotic pressure liquid supplied to an outlet side of the other flow path are arranged in the other pipe.

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