JP2021041374A - Concentration system - Google Patents

Abstract

To provide a concentration system which uses brine concentration (BC), and in which appropriate management can be implemented during operation of the concentration system.SOLUTION: A concentration system is provided, comprising a semi-permeable membrane module which has a semi-permeable membrane and a first chamber and a second chamber partitioned by the semi-permeable membrane, wherein the semi-permeable membrane module flows first object liquid to the first chamber at prescribed pressure, and flows second object liquid to the second chamber at pressure lower than the prescribed pressure, accordingly, causes water included in the first object liquid inside the first chamber to transfer to the second object liquid in the second chamber via the semi-permeable membrane, and discharges concentrated liquid from the first chamber, and discharges diluted liquid from the second chamber. The concentration system further comprises a monitoring device monitoring at least one parameter related to the operation of the concentration system.SELECTED DRAWING: Figure 1

Description

The present invention relates to a concentration system.

For example, for the purpose of reducing the energy required for desalination using the reverse osmosis (RO) method, a high-pressure target liquid is flowed through the first chamber of the semipermeable membrane module, and a low-pressure target is flowed into the second chamber. By flowing the liquid and transferring the water contained in the target liquid in the first chamber to the target liquid in the second chamber via the semipermeable membrane, the concentrated target liquid is discharged from the first chamber and the second chamber is discharged. A membrane separation method (brine concentration) for discharging the target liquid diluted from the above has been studied (see, for example, Patent Document 1: Japanese Patent Application Laid-Open No. 2018-1110).

Japanese Unexamined Patent Publication No. 2018-1110

In the semipermeable membrane module used for brine concentration (BC), the semipermeable membrane has impurities such as turbidity (for example, fine particles, microorganisms, scale components) on the surface over time according to the amount of the membrane separation treatment of the target liquid. Adhesion causes problems such as deterioration of separation performance (filtration efficiency). Therefore, it is desirable that the semipermeable membrane of the semipermeable membrane module be washed at an appropriate frequency and for an appropriate time according to the degree of adhesion of impurities.

The amount of water permeated by the semipermeable membrane changes depending on parameters such as concentration (osmotic pressure), temperature, and pH. Such a change in the amount of water permeation may increase the adhesion of impurities such as scale precipitation to the semipermeable membrane. For example, if the amount of water permeated is larger than expected, the concentration rate may increase due to the increase in permeated water, and scale precipitation or the like may easily occur. Therefore, it is desirable to perform process control in consideration of the above parameters.

As described above, in the operation of the enrichment system using BC, it is desired to perform appropriate management according to various factors.

Therefore, it is an object of the present invention to provide a concentration system capable of performing appropriate management during operation of the concentration system using brine concentration (BC).

(1) It has a semipermeable membrane and a first chamber and a second chamber partitioned by the semipermeable membrane, and the first target liquid is flowed into the first chamber at a predetermined pressure, and the second target liquid is poured. By flowing the water into the second chamber at a pressure lower than the predetermined pressure, the water contained in the first target liquid in the first chamber is passed through the semipermeable membrane to the second target liquid in the second chamber. A concentration system including a semipermeable membrane module, which discharges the concentrated solution from the first chamber and discharges the diluted solution from the second chamber.
Further, a concentration system comprising a monitoring device that monitors at least one parameter relating to the operation of the concentration system.

(2) The concentration system according to (1), comprising the plurality of the semipermeable membrane modules.

(3) The concentration system according to (1) or (2), wherein the parameter includes at least one flow rate and pressure of the first target liquid and the second target liquid in the semipermeable membrane module.

(4) The concentration system according to any one of (1) to (3), further comprising a control mechanism that controls the operation of the concentration system based on the at least one parameter monitored by the monitoring device.

(5) Further equipped with a reverse osmosis module, which separates and recovers water from the stock solution pressurized to a predetermined pressure via a reverse osmosis membrane and discharges the concentrated stock solution which is the concentrated stock solution.
The concentration system according to any one of (1) to (4), wherein the concentrated stock solution is flowed into the first chamber at a predetermined pressure as the first target solution.

In the present invention, by monitoring various parameters in the concentration system, it is possible to provide a concentration system capable of performing appropriate management during operation of the concentration system using brine concentration (BC).

It is a schematic diagram which shows the enrichment system of Embodiment 1. It is a schematic diagram which shows the enrichment system of Embodiment 2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals represent the same parts or equivalent parts. Further, the dimensional relationships such as length, width, thickness, and depth are appropriately changed for the purpose of clarifying and simplifying the drawings, and do not represent the actual dimensional relationships.

<Embodiment 1>
With reference to FIG. 1, the concentration system of the present embodiment includes a semipermeable membrane module 1 and a monitoring device 3.
The semipermeable membrane module 1 has a semipermeable membrane 10 and a first chamber 11 and a second chamber 12 partitioned by the semipermeable membrane, and the concentrated stock solution is used as the first target solution in the first chamber at a predetermined pressure. By flowing the second target liquid into the second chamber 12 at a pressure lower than a predetermined pressure (pressure of the first liquid), the water contained in the first target liquid in the first chamber 11 is semipermeable. It is transferred to the second target liquid in the second chamber 12 through the membrane, the concentrated liquid is discharged from the first chamber 11, and the diluted liquid is discharged from the second chamber 12.
The monitoring device 3 monitors at least one parameter relating to the operation of the enrichment system.

[Semipermeable membrane module]
The plurality of semipermeable membrane modules 1 have a semipermeable membrane 10 and a first chamber 11 and a second chamber 12 partitioned by the semipermeable membrane 10.

The number of semipermeable membrane modules 1 is not particularly limited, but as shown in FIG. 1, when the concentrating system includes a plurality of semipermeable membrane modules 1, the fluid flowing between the modules flows at a high pressure, and so on. Since there are few flow paths that can be opened and sampling is difficult, it is particularly effective to install sensors in each flow path in advance and monitor various parameters obtained from the sensors to control the process.

The first target liquid flows into the first chamber 11 at a predetermined pressure, and the second target liquid flows into the second chamber 12 at a pressure lower than the predetermined pressure. As a result, the water contained in the first target liquid in the first chamber 11 is transferred to the second target liquid in the second chamber 12 via the semipermeable membrane 10, and is concentrated (concentrated) from the first chamber 11. The first target liquid) is discharged, and the diluted liquid (diluted second target liquid) is discharged from the second chamber 12.

The first target liquid and the second target liquid may be the same liquid. For example, as shown in FIG. 1, a part of the first target liquid having a predetermined pressure is flowed into the second chamber at a pressure lower than the predetermined pressure by passing through the pressure lowering device 4. May be good.

The pressure lowering device 4 includes, for example, a flow dividing valve and a decompressor that can separately flow a first target liquid having a predetermined pressure into a flow path to the second chamber 12 of the semipermeable membrane module and another flow path. Alternatively, an energy recovery device or the like can be mentioned. Here, the pressure lowering device 4 (flow dividing valve) has a function of reducing the pressure of the target liquid flowing into the second chamber 12 to a pressure lower than a predetermined pressure. By using such a pressure reducing device, for example, there is an advantage that only one flow path of the target liquid on the upstream side of the semipermeable membrane module is required.

In the case of FIG. 1, since the target liquids flowing into the first chamber 11 and the second chamber 12 of the semipermeable membrane module (each of the semipermeable membrane modules 1) are the same liquid, they have basically the same osmotic pressure. .. Therefore, unlike the RO method, a high pressure for causing reverse osmosis against the high osmotic pressure difference between the target liquid (high osmotic liquid) and fresh water is not required, and pressure is applied at a relatively low pressure. Membrane separation of the target solution can be performed (some target solutions can be diluted and some other target solutions can be concentrated).

However, in the present embodiment, the second target liquid supplied to the second chamber 12 of the semipermeable membrane module may be a liquid independent of the first target liquid supplied to the first chamber 11.

The first target liquid flowing through the first chamber 11 and the second target liquid flowing through the second chamber 12 are different liquids, and even if the concentrations are different between the two, the osmotic pressure difference (absolute value) is the first. Theoretically, membrane separation by BC is feasible if the pressure is lower than the pressure of the first target liquid supplied to the chamber 11. In this case, the difference between the osmotic pressure of the first target liquid flowing into the first chamber 11 (high pressure side) and the osmotic pressure of the second target liquid supplied to the second chamber 12 (low pressure side) is the first chamber 11 It is preferably 30% or less of the predetermined pressure of the first target liquid supplied to the water.

Further, the BC process using the semipermeable membrane module 1 is preferably a multi-stage process using a plurality of semipermeable membrane modules (connected in series) as shown in FIG. 1. It may be a one-step process using one semipermeable membrane module.

In the brine concentration (BC), which is a membrane separation process in the semipermeable membrane module, in order to transfer water from the first chamber 11 to the second chamber 12 via the semipermeable membrane 10 of the semipermeable membrane module, a first It is necessary to make the pressure of the first target liquid supplied to the chamber 11 larger than the osmotic pressure difference between the first target liquid and the second target liquid flowing on both sides of the semipermeable membrane 10. Therefore, in order to highly concentrate the first target liquid in one step (one semipermeable membrane module), it is necessary to supply at a correspondingly high pressure, and the energy cost for operating the pump is high. There are disadvantages such as an increase in. Therefore, BC may be carried out by a multi-step process using a plurality of semipermeable membrane modules for the purpose of stepwise concentration step and reducing the pressure required for BC. BC by such a multi-step process is disclosed in, for example, Japanese Patent Application Laid-Open No. 2018-069198.

Examples of the semipermeable membrane include a semipermeable membrane called a reverse osmosis (RO) membrane, a forward osmosis (FO) membrane, and a nanofiltration (NF) membrane. When a reverse osmosis membrane, a forward osmosis membrane, or a nanofiltration membrane is used as the semipermeable membrane, the pressure of the first target liquid supplied to the first chamber 11 is preferably 6 to 10 MPa.

Usually, the pore diameters of the RO membrane and the FO membrane are about 2 nm or less, and the pore diameter of the UF membrane is about 2 to 100 nm. The NF membrane has a relatively low inhibition rate of ions and salts among the RO membranes, and the pore size of the NF membrane is usually about 1 to 2 nm. When an RO membrane, an FO membrane, or an NF membrane is used as the semipermeable membrane, the salt removal rate of the RO membrane, the FO membrane, or the NF membrane is preferably 90% or more.

The material constituting the semipermeable membrane is not particularly limited, and examples thereof include a cellulosic resin, a polysulfone resin, and a polyamide resin. The semipermeable membrane is preferably composed of a material containing at least one of a cellulosic resin and a polysulfone resin.

The cellulosic resin is preferably a cellulosic acetate resin. Cellulose acetate-based resins are resistant to chlorine, which is a bactericidal agent, and have the characteristic of being able to suppress the growth of microorganisms. The cellulose acetate-based resin is preferably cellulose acetate, and more preferably tricellulose triacetate from the viewpoint of durability.

The polysulfone-based resin is preferably a polyether sulfone-based resin. The polyether sulfone-based resin is preferably a sulfonated polyether sulfone.

The shape of the semipermeable membrane 10 (and the reverse osmosis membrane 20 described above) is not particularly limited, and examples thereof include a flat membrane and a hollow fiber membrane. In FIG. 1, the semipermeable membrane 10 is a simplified drawing of the flat membrane, but the shape is not particularly limited to such a shape. The hollow fiber membrane (hollow fiber type semipermeable membrane) is advantageous in that the membrane area per module can be increased and the permeation efficiency can be improved as compared with a spiral type semipermeable membrane or the like.

The form of the semipermeable membrane module (and the reverse osmosis module 2 described above) is not particularly limited, but when a hollow fiber membrane is used, a module in which the hollow fiber membrane is arranged straight or a hollow fiber membrane is used as a core tube. Examples include a wrapped cross-wind module. When a flat film is used, examples thereof include a laminated module in which flat films are stacked, and a spiral module in which the flat film is wound around a core tube in an envelope shape.

As an example of a specific hollow fiber membrane, there is a single-layer structure membrane which is entirely composed of a cellulosic resin. However, the monolayer structure referred to here does not have to be a uniform film as a whole, and has, for example, a dense layer in the vicinity of the outer peripheral surface as disclosed in Japanese Patent Application Laid-Open No. 2012-115835. It is preferable that the dense layer is a separation active layer that substantially defines the pore size of the hollow fiber membrane.

As another specific example of the hollow fiber membrane, a two-layer structure having a dense layer made of a polyphenylene resin (for example, sulfonated polyether sulfone) on the outer peripheral surface of a support layer (for example, a layer made of polyphenylene oxide). Membrane is mentioned. Another example is a two-layered film having a dense layer made of a polyamide resin on the outer peripheral surface of a support layer (for example, a layer made of polysulfone or polyethersulfone).

In a semipermeable membrane module using a hollow fiber membrane, the outside of the hollow fiber membrane is usually the first chamber. This is because even if the fluid flowing inside the hollow fiber membrane (hollow fiber portion) is pressurized, the pressure loss becomes large and it is difficult for the pressurization to work sufficiently.

[Monitoring device]
The monitoring device 3 monitors at least one parameter relating to the operation of the enrichment system.

The monitoring device 3 is configured so that, for example, information on various parameters (measured values) acquired by at least one sensor 5 can be acquired. For example, the monitoring device 3 can communicate with the sensor 5 by wire communication or wireless communication.

The sensor 5 is provided, for example, in the flow path constituting the concentration system. It is preferable that the sensor 5 is installed at least in the flow path on the inflow side and / or the discharge side of the first chamber 11 and / or the second chamber 12 of the semipermeable membrane module 1 used for BC.

The parameters to be monitored include, for example, flow rate, pressure, differential pressure, temperature, TDS (total dissolved solids), electrical conductivity, TOC (total organic carbon), COD (chemical oxygen demand), BOD (biochemistry). Target oxygen demand), SS (suspended solids), DO (dissolved oxygen), residual chlorine concentration, ORP (oxidation-reduction potential), pH, hardness, alkalinity and the like. Examples of the sensor 5 include a measuring device for these parameters.

The parameters preferably include the flow rate and pressure of at least one of the first target liquid and the second target liquid in the semipermeable membrane module 1. The flow rate and pressure of the first target liquid are preferably the flow rate and pressure of the inflow side (inlet) and the discharge side (outlet) of the first chamber 11. The flow rate of the second target liquid is preferably the flow rate and pressure of the inflow side (inlet) and the discharge side (outlet) of the second chamber 12.

The monitoring device 3 acquires, for example, parameters (measured values) obtained by these sensors 5 (measurement devices) periodically or continuously.

By monitoring various parameters in the concentration system by the monitoring device 3, appropriate management can be performed during the operation of the concentration system using the brine concentration (BC).

By monitoring various parameters in the concentration system, for example, it is possible to efficiently carry out processing such as cleaning and sterilization, judge or predict troubles, and respond promptly to troubles, and stabilize the concentration system. It becomes possible to drive.

<Embodiment 2>
With reference to FIG. 2, the enrichment system of this embodiment further comprises a control mechanism 6.

[Control mechanism]
The control mechanism 6 controls the operation of the enrichment system based on the at least one parameter monitored by the monitoring device 3. The control mechanism 6 preferably controls, for example, the flow rate and pressure of at least one of the first target liquid and the second target liquid in the semipermeable membrane module 1.

Examples of the control by the control mechanism 6 include feedback control and trouble detection.

As feedback control, for example, in the control unit, pumps (pump 1a, high-pressure pump 2a) are used by using physical quantities (parameters) in the system of the concentration system so that the flow rate of permeated water becomes a preset target flow rate value. Etc.), the optimum drive frequency is calculated, and the value signal is output to the pump inverter to control the drive frequency of the pump.

Further, for example, in the first target liquid concentrated in the first chamber 11 of the semipermeable membrane module 1, the concentration ratio, that is, the flow rate of permeated water ( In order to adjust [flow rate at the inlet of the first chamber 11]-[flow rate at the outlet of the first chamber 11]), it is possible to control the flow rate, pressure, etc. of the first target liquid and the second target liquid. The permissible concentration of the scale component in the first target liquid (maximum concentration in the range where scale such as calcium carbonate does not precipitate) is, for example, parameter information such as pH, hardness, alkalinity, temperature of the first target liquid, and scale (carbonate). It can be calculated based on the solubility of calcium, etc.) and various scale precipitation determination formulas.

As for the detection of troubles, for example, when a sudden change in parameters due to damage of the semipermeable membrane module 1 and the RO module 2 such as tearing of the semipermeable membrane 10 and the RO membrane 20 is detected, a warning is issued. Control is mentioned. It is also possible to control the frequency, time, degree, etc. of cleaning based on a parameter that is an index of the degree of contamination of the semipermeable membrane of the semipermeable membrane module.

[RO + BC]
As a concentration system using BC, as shown in FIG. 2, the concentrated stock solution discharged from the reverse osmosis (RO) module 2 is flowed into the first chamber of the semipermeable membrane module that can be operated at a higher pressure, and is described above. A concentration system that further concentrates the concentrated stock solution by brine concentration (BC) under ultra-high pressure conditions compared to the RO method is also being studied.

The reverse osmosis module 2 separates and recovers water from the undiluted solution pressurized to a predetermined pressure via the reverse osmosis membrane 20, and discharges the concentrated undiluted solution which is the concentrated undiluted solution.

With reference to FIG. 2, a high pressure pump 2a is provided on the upstream side of the reverse osmosis (RO) module 2. The high-pressure pump 2a boosts the stock solution to a predetermined pressure and supplies it to the first chamber 21 of the RO module 2. The RO module 2 separates water (permeated water) from the undiluted solution pressurized to a predetermined pressure to the second chamber 22 side via the reverse osmosis (RO) membrane 20, thereby producing a concentrated undiluted solution which is a concentrated undiluted solution. The water is discharged from the first chamber 21 and the water is discharged from the second chamber 22.

In the present specification, the "stock solution" is not particularly limited as long as it is a liquid containing water supplied to the RO module 2, and may be either a solution or a suspension. Examples of the undiluted solution include seawater, river water, brackish water, wastewater and the like. Examples of wastewater include industrial wastewater, domestic wastewater, oil field or gas field wastewater, and the like.

A pretreatment device (not shown) may be provided on the upstream side of the high-pressure pump 2a in order to remove turbid substances (fine particles, microorganisms, scale components, etc.) contained in the undiluted solution. Examples of the pretreatment device include a sand filtration device, a filtration device using a UF (Ultrafiltration) membrane, an MF (Microfiltration) membrane, etc., chlorine, sodium hypochlorite, a flocculant, and scale. Examples include an addition device such as an inhibitor and a pH adjustment device. The scale inhibitor is an additive having an action of preventing or suppressing the precipitation of scale components in the liquid as scale. Examples of the anti-scale agent include compounds such as polyphosphoric acid-based, phosphonic acid-based, phosphinic acid-based, and polycarboxylic acid-based compounds.

In the present embodiment, the semipermeable membrane module 1 is connected to the downstream side of the RO module 2 (first chamber 21). The first target liquid supplied to the first chamber 11 of the semipermeable membrane module (each of the semipermeable membrane modules 1) is a concentrated stock solution discharged from the first chamber 21 of the RO module 2. Since the concentrated stock solution discharged from the RO module 2 has a high pressure, it is sent to the semipermeable membrane module side by the pressure.

In a concentration system that combines the RO method and the BC method as shown in FIG. 2, since concentration is performed at a high concentration rate, impurities such as scale precipitation are likely to occur on the surface of the semipermeable membrane. It is especially effective to monitor various parameters and control the process.

In this embodiment, the enrichment system may further include an energy recovery device 7. When the energy recovery device 7 is installed as shown in FIG. 2, the pressure energy of the liquid (concentrated first target liquid) discharged from the first chamber 11 of the semipermeable membrane module 1 is recovered to recover the pressure energy of the RO module. By applying the undiluted solution supplied to No. 2, the energy required for the high-pressure pump 2a can be reduced.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Semipermeable membrane module, 1a pump, 10 Semipermeable membrane, 11 1st chamber, 12 2nd chamber, 2 Reverse osmosis (RO) module, 2a High pressure pump, 20 Reverse osmosis (RO) membrane, 21 1st chamber, 22 Room 2, 3 monitoring device, 4 pressure drop device, 5 sensor, 6 control mechanism, 7 energy recovery device.

Claims (5)

It has a semipermeable membrane and a first chamber and a second chamber partitioned by the semipermeable membrane, the first target liquid is flowed into the first chamber at a predetermined pressure, and the second target liquid is flown into the predetermined chamber. By flowing the water into the second chamber at a pressure lower than the pressure, the water contained in the first target liquid in the first chamber is transferred to the second target liquid in the second chamber via the semipermeable membrane. , A concentrating system including a semipermeable membrane module, which discharges a concentrated solution from the first chamber and discharges a diluted solution from the second chamber.
Further, a concentration system comprising a monitoring device that monitors at least one parameter relating to the operation of the concentration system. The concentration system according to claim 1, further comprising the plurality of the semipermeable membrane modules. The concentration system according to claim 1 or 2, wherein the parameters include at least one flow rate and pressure of the first target liquid and the second target liquid in the semipermeable membrane module. The enrichment system according to any one of claims 1 to 3, further comprising a control mechanism that controls the operation of the enrichment system based on the at least one parameter monitored by the monitoring device. Further equipped with a reverse osmosis module, which separates and recovers water from the stock solution pressurized to a predetermined pressure via a reverse osmosis membrane and discharges the concentrated stock solution which is the concentrated stock solution.
The concentration system according to any one of claims 1 to 4, wherein the concentrated stock solution is flowed into the first chamber as the first target solution at a predetermined pressure.

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