JP2010089036A - Membrane separation apparatus, and operation management method of membrane separation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane separation apparatus and the operation management method of the same which is capable of recovering the energy which the reject from a reverse osmotic membrane cartridge has at higher efficiency than the time when a Pelton Wheel is used, which is capable of maintaining water producing capability (desalination rate), and which is capable of determining a proper cleaning timing of the reverse osmotic membrane and breakdown of an energy recovery device. <P>SOLUTION: The membrane separation apparatus includes: a supplied sea water bypass line 15 which introduces concentrated water from the reverse osmotic membrane cartridge 4, and, by using a displacement type energy recovery device 5 which pressurize a part of the supplied raw water, which joins the pressurized raw water to a high pressure raw water of a high pressure line 10 which connects the high pressure pump 3 and the reverse osmotic membrane cartridge 4; a booster pump 6 which pressurizes the raw water flowing in the bypass line 15; and a control means which controls the amount of raw water supplied to the reverse osmotic membrane cartridge 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention resides in a membrane separation device for supplying raw water such as seawater to a reverse osmosis membrane cartridge by pressurizing with a high-pressure pump to obtain diluted water such as fresh water, and an operation management method thereof.

  If the said membrane separation apparatus is demonstrated with seawater desalination equipment, seawater desalination equipment is mainly comprised from the pre-processing apparatus, the high pressure pump, and the reverse osmosis membrane cartridge. The taken seawater is adjusted to a condition of constant water quality by a pretreatment device, then pressurized by a high pressure pump and pumped to a reverse osmosis membrane cartridge. A part of the high-pressure seawater in the reverse osmosis membrane cartridge overcomes the reverse osmosis pressure, passes through the reverse osmosis membrane, and is taken out as fresh water from which the salt content has been removed. Other seawater is discharged as a reject from the reverse osmosis membrane cartridge in a state where the salinity concentration is increased and concentrated. More than half of the electric power used, which is the maximum operating cost of seawater desalination facilities, is spent on pressurizing seawater with a high-pressure pump. Therefore, Patent Documents 1 to 3 disclose a method for recovering pressure energy held by a high salinity reject discharged from a reverse osmosis membrane cartridge.

  In the membrane separation apparatus shown in Patent Documents 1 to 3, a Pelton turbine is used for energy recovery, and a reject from the reverse osmosis membrane cartridge is supplied to the Pelton turbine via a flow rate control valve. It is configured to support rotational force. Some use a reverse pump for energy recovery. As described above, those using a Pelton turbine or reverse pump for energy recovery have a problem of low energy recovery efficiency.

  On the other hand, positive displacement energy recovery devices (for example, positive displacement piston pumps) generally have high energy recovery efficiency, and there are some which use positive displacement energy recovery devices for seawater desalination facilities. However, the existing type using the volume type for the energy recovery device is based on the focus on only the energy recovery efficiency and operation of the energy recovery device itself, and the flow rate is adjusted in consideration of the osmotic pressure characteristics of the reverse osmosis membrane. It was not a thing. Moreover, when the positive displacement type is used for the energy recovery device, the failure item may be leakage of concentrated water in the recovery device. If the leakage of concentrated water increases, the desalination rate decreases relatively, leading to a decrease in the performance of the seawater desalination facility.

In addition, in a seawater desalination system using a conventional reverse osmosis membrane cartridge, the reverse osmosis membrane of the reverse osmosis membrane cartridge accumulates deposits as the operating time elapses, and the membrane characteristics deteriorate. However, the timing of cleaning is left to the judgment of individual workers, and it has not been performed at an appropriate time that requires cleaning due to deterioration of the reverse osmosis membrane.
JP 59-189910 A JP 59-199004 A International Publication No. 1985/001221

  The present invention has been made in view of the above points, and can recover the energy of the concentrated water (reject) from the reverse osmosis membrane cartridge with higher efficiency than when using a Pelton turbine or a reverse pump for energy recovery. An object of the present invention is to provide a membrane separation device capable of maintaining saltwater performance (desalting rate), appropriate reverse osmosis membrane cleaning timing and energy recovery device failure, and an operation management method for the membrane separation device.

  In order to solve the above-mentioned problems, the present invention comprises a high-pressure pump that pressurizes the supplied raw water, a reverse osmosis membrane cartridge, and energy recovery means disposed downstream of the reverse osmosis membrane cartridge on the concentrated water side, and is added by a high-pressure pump. In a membrane separator that introduces pressurized high-pressure raw water into a reverse osmosis membrane cartridge and separates it into dilute water and concentrated water, the concentrated water is introduced from the reverse osmosis membrane cartridge as an energy recovery means, and a part of the supplied raw water is removed. In the middle of the bypass pipe, a bypass pipe that joins the high-pressure raw water flowing through the high-pressure line that connects the high-pressure pump and reverse osmosis membrane cartridge with the positive-pressure energy recovery equipment A booster pump that pressurizes the raw water that flows through the bypass pipe and the flow rate of the raw water supplied to the reverse osmosis membrane cartridge And that the raw water flow rate control means, and wherein the state detecting means for detecting the state of each part of the membrane separation device, that the state detecting means is provided a defect corresponding control means corresponding if failure of each part detected.

  In the membrane separation apparatus according to the present invention, the raw water flow rate control means controls the flow rate of the raw water supplied to the reverse osmosis membrane cartridge by controlling the rotation speed of the high-pressure pump and / or the booster pump. .

  Further, the present invention provides a membrane separation apparatus, wherein the concentrated water discharged from the high-pressure line, the bypass line, and the reverse osmosis membrane cartridge is guided to the volumetric energy recovery apparatus, and the concentrated water is drained from the volumetric energy recovery apparatus. A flow rate control valve is provided in each of the concentrated water bypass line for draining the concentrated water by bypassing the positive-capacity energy recovery device from the drainage line and the concentration line, and the raw water flow rate control means controls at least one of the flow rate control valves. The flow rate of raw water supplied to the reverse osmosis membrane cartridge is controlled.

  In the membrane separation apparatus, the present invention provides a first concentration sensor that detects the concentration of dilute water, a second sensor that detects the concentration of concentrated water flowing through the bypass pipe, and a third sensor that detects the concentration of raw feed water. Concentration sensor and a sensor for detecting the temperature of the raw water, and the state detection means has a function of detecting a failure of the volumetric energy recovery device and / or reverse osmosis membrane deterioration of the reverse osmosis membrane cartridge from the output of each sensor. It is characterized by being.

  The present invention also provides a concentrated water bypass line for draining the concentrated water introduced from the reverse osmosis membrane cartridge into the positive displacement energy recovery device by bypassing the positive displacement energy recovery device, and the concentrated water. A flow control valve provided in the bypass line, and when the state detection means detects a failure of the positive displacement energy recovery device, the failure response control means opens the flow control valve provided in the concentrated water bypass line to supply the concentrated water. It is characterized by draining.

  Further, according to the present invention, in the above membrane separation apparatus, when the state detection means detects a failure of the positive displacement energy recovery apparatus, the failure countermeasure control means stops the booster pump, and the reverse osmosis membrane cartridge is operated only by the high pressure pump. It is characterized by supplying raw water.

  As described above, high-pressure concentration discharged from the reverse osmosis membrane cartridge by introducing the concentrated water from the reverse osmosis membrane cartridge as an energy recovery means and pressurizing a part of the supplied raw water. Water pressure energy can be recovered effectively.

  Also, for example, when the state detection means detects a failure of the positive displacement energy recovery device, the failure countermeasure control means opens the flow control valve provided in the concentrated water bypass line to drain the concentrated water, and the concentrated water is When there is a backup pump to prevent trapping in the energy recovery device, stop the booster pump, supply raw water to the reverse osmosis membrane cartridge only by operating the high pressure pump, or back up the high pressure pump It is possible to quickly take measures such as stopping the booster pump, operating the backup pump, and supplying raw water to the reverse osmosis membrane cartridge by operating the high-pressure pump and the backup pump.

  Further, for example, when the state detection means detects reverse osmosis membrane deterioration of the reverse osmosis membrane cartridge, the reverse osmosis membrane can be washed or replaced at an appropriate time.

  The present invention also includes a high-pressure pump that pressurizes the supplied raw water, a reverse osmosis membrane cartridge, and energy recovery means disposed downstream of the reverse osmosis membrane cartridge on the concentrated water side, and is pressurized by a high-pressure pump. In the operation management method of the membrane separation device that introduces raw water into the reverse osmosis membrane cartridge and separates it into dilute water and concentrated water, while using a positive displacement energy recovery device as energy recovery means, a booster pump is provided, and from the reverse osmosis membrane cartridge Concentrated water is introduced into the volumetric energy recovery device, part of the supplied raw water is pressurized, the pressurized raw water is pressurized with a booster pump, and the pressurized raw water is connected to the high-pressure pump and reverse osmosis membrane cartridge The high pressure raw water flowing through the connecting pipe and the flow rate of the raw water supplied to the reverse osmosis membrane cartridge are controlled, and the shape of each part of the membrane separation device Monitoring a state detecting means for detecting, said state detecting means and controls the respective units according to the defect in the defect response control means upon detection of failure of each component.

According to the present invention, the following excellent effects can be expected.
-Since the pressure energy of the high-pressure concentrated water discharged from the reverse osmosis membrane cartridge can be recovered effectively, the required energy of the membrane separation device is small and the operation cost is low.
-By detecting the failure of the positive displacement energy recovery device, it is possible to promptly respond to repair or replacement.
-Since the deterioration of the reverse osmosis membrane of the reverse osmosis membrane cartridge can be detected, it can be washed or replaced at an appropriate time.

  Embodiments of the present invention will be described below with reference to the drawings. A seawater desalination apparatus will be described as an example of a membrane separation apparatus. FIG. 1 is a schematic diagram showing a first aspect of a seawater desalination apparatus according to the present invention. As shown in the figure, the seawater desalination apparatus includes a water intake pump 1, a pretreatment device 2, a high pressure pump (HP) 3, a reverse osmosis membrane cartridge 4, a positive displacement energy recovery device (ER) 5, a booster pump (BP) 6, A control device 7 is provided.

  The seawater 100 taken by the intake pump 1 is adjusted to a predetermined water quality condition by the pretreatment device 2 and then supplied to the high-pressure pump (HP) 3 driven by the electric motor 8 through the supply line 9. It is pressurized by the high pressure pump (HP) 3 and flows into the reverse osmosis membrane cartridge 4 through the high pressure line 10 which is a connecting pipe connecting the high pressure pump (HP) 3 and the reverse osmosis membrane cartridge 4. A part of the seawater in the high pressure chamber 11 of the reverse osmosis membrane cartridge 4 overcomes the reverse osmosis pressure and passes through the reverse osmosis membrane 4 a, the solute (salt content) is removed, and it is taken out as diluted water (demineralized water) 102. The other seawater is discharged from the reverse osmosis membrane cartridge 4 to the concentrated seawater line 13 in a state where the salinity is increased and concentrated.

  The pressure energy held by the reject 103 (concentrated seawater), which is high-pressure concentrated water discharged from the reverse osmosis membrane cartridge 4, is introduced into the positive displacement energy recovery device (ER) 5, and the reject 103 (concentrated seawater) that has lost the pressure energy. ) Is discarded through the drainage line 14 as low-pressure concentrated seawater (reject) 104 from which energy has been recovered. As the positive displacement energy recovery device (ER) 5, for example, a positive displacement piston pump, which will be described in detail later, is used. A portion of the seawater in the supply line 9 is pumped up by the positive displacement piston pump, and the supply seawater bypass is performed. It is discharged to the line 15 and finally joins the high-pressure seawater passing through the high-pressure line 10.

  Supply due to pressure loss in reverse osmosis membrane cartridge 4 and concentrated seawater line 13, pressure loss in control valve and switching valve of positive displacement energy recovery device (ER) 5, leakage loss between energy recovery chamber and internal piston, etc. The pressure of seawater in the seawater bypass line 15 is lower than the pressure of seawater flowing into the reverse osmosis membrane cartridge 4 through the high pressure line 10. Therefore, in order to join the seawater passing through the supply seawater bypass line 15 and the seawater passing through the high-pressure line 10, a booster pump (BP) 6 driven by the electric motor 16 is installed in the middle of the supply seawater bypass line 15, Seawater in the supply seawater bypass line 15 is pressurized by the pressure loss. The booster pump (BP) 6 can increase the pressure of seawater passing through the supply seawater bypass line 15 to a pressure at which the seawater passing through the high pressure line 10 can be merged with a smaller electric capacity than the high pressure pump (HP) 3.

The control device 7 includes a pump discharge flow rate (supply seawater flow rate) calculation unit 20 that calculates a discharge flow rate Q _0-1 of the high-pressure pump (HP) 3 and a discharge flow rate Q _0-2 of the booster pump (BP) 6. The diluted water flow rate setting unit 21 that sets the diluted water flow rate as the set diluted water amount Q _S1 , the BP rotation number selection unit 22-1 that selects the rotation number of the booster pump (BP) 6, and the Q− of the booster pump (BP) 6 A storage unit 23 for storing the H curve and the QH curve of the high-pressure pump (HP) 3 is provided. In this case, the rotation speed of the high-pressure pump (HP) 3 is kept constant and the rotation speed of the booster pump 6 is controlled to obtain a predetermined dilute water flow rate Q ₁ . As shown in FIG. 13, when the valve opening degree selection units 22-2 and 22-3 are provided and the opening / closing degree of the valve is controlled with respect to the set discharge flow rate of the high pressure pump (HP) 3 and the booster pump (BP) 6, As shown in FIG. 14, the rotation speed of the booster pump (BP) 6 may be constant, and the rotation speed of the high-pressure pump (HP) 3 may be controlled using the HP rotation speed selection unit 22-4.

The pump discharge flow rate calculation unit 20 includes a discharge pressure P _{0-1 of} the high pressure pump (HP) 3 detected by the pressure sensor 26, a discharge pressure P _{0-2 of} the booster pump (BP) 6 detected by the pressure sensor 27, and a pressure. The pressure P ₂ on the high pressure chamber 11 side of the reverse osmosis membrane cartridge 4 detected by the sensor 19 is input. The pump discharge water flow rate calculation unit 20 considers changes in the membrane characteristics of the reverse osmosis membrane 4a of the reverse osmosis membrane cartridge 4 and the concentration of sea water in the seawater 100 (salt content), and the like. _The supplied seawater flow rate (pump discharge flow rate) Q ₀ is calculated so that ₁ becomes the set diluted water amount Q _S1 set by the diluted water flow rate setting unit 21. That is, the discharge flow rate Q _0-1 of the high-pressure pump (HP) 3 and the discharge flow rate Q _0-2 of the booster pump (BP) 6 are calculated so that the diluted water flow rate Q ₁ becomes the set diluted water flow rate Q _S1 .

The BP rotation speed selection unit 22-1 is calculated by the pump discharge flow rate calculation unit 20 with reference to the QH curves of the high pressure pump (HP) 3 and the booster pump (BP) 6 stored in the storage unit 23. The number of rotations of the booster pump (BP) 6 is selected so that the pump discharge flow rate Q ₀ (Q _0-1 + Q _0-2 ) can be obtained (here, the discharge flow rate Q _0-1 of the high pressure pump (HP) 3 is set to a predetermined value). And a predetermined pump discharge flow rate Q ₀ is obtained by controlling the rotation speed of the booster pump (BP) 6. The selected number of revolutions is sent to the electric motor 16 via a driver (here, the inverter 24), and the booster pump (BP) 6 rotates at the selected number of revolutions.

In FIG. 1, P _0-1 is the discharge pressure of the high pressure pump (HP) 3, Q _0-1 is the discharge flow rate of the high pressure pump (HP) 3, and C _0-1 is the solute (salt content) concentration of the high pressure line 10. , P _0-2 is the discharge pressure of the booster pump (BP) 6, Q _0-2 is the discharge flow rate of the booster pump (BP) 6, C _0-2 is the solute (salt content) concentration of the supply seawater bypass line 15, and P ₁ Is the dilute water side (demineralized water side) pressure of the reverse osmosis membrane cartridge 4, Q ₁ is the flow rate of dilute water (demineralized water), and C ₁ is the solute (salt content) concentration of dilute water.

Figure 2 is a functional block diagram of the control device 7, the control device 7, D _W -T functional unit 7-1, [Delta] P-Q ₁ functional section 7-2, [pi-C _M functional unit 7-3, Q- An H function unit 7-4 is provided. As shown in the figure, the D _W -T function unit 7-1 includes data indicating D _W / T (D _W is the diffusion coefficient of water in the reverse osmosis membrane 4a) on the vertical axis and the temperature T of the supplied seawater on the horizontal axis. ing. The ΔP-Q ₁ function unit 7-2 includes data indicating the pressure ΔP exceeding the reverse osmosis pressure π of the reverse osmosis membrane 4a on the vertical axis and the diluted water flow rate Q ₁ on the horizontal axis. The π-C _M function unit 7-3 includes data indicating the osmotic pressure π on the vertical axis and the seawater concentration C _M on the horizontal axis. The QH function unit 7-4 includes data (QH curve) indicating the combined water head pressure H of the high pressure pump (HP) 3 and the booster pump (BP) on the vertical axis and the discharge flow rate Q on the horizontal axis.

Next, the operation of the control device 7 will be described based on the functional block diagram of FIG. The D _W -T function unit 7-1 calculates D _W / T from the temperature T of the supplied seawater detected by the temperature sensor 43 from the relational curve 55 of T and D _W / T, and the reverse osmosis membrane cartridge 4 The coefficient K determined by the type of the reverse osmosis membrane 4a is obtained from the following equation.
K = K ₀ (D _W / T)
(Where K ₀ is a known constant determined by the type of reverse osmosis membrane 4a, and D _W is the diffusion coefficient of water)
Here, the discharge pressure (supply seawater pressure) P ₀ before the setting change is temporarily set.
Further, as described above, the π-C _M function unit 7-3 shows the osmotic pressure π on the vertical axis and the sea water solubility (salt content) concentration C _M on the horizontal axis, and the curve 54 shows the sea water solubility (salt content) concentration C. The relationship between _M and osmotic pressure π is shown. If seawater solute (salt) concentration C _M from the relationship of the curve 54 is obtained, it is obtained seawater osmotic pressure [pi _M feed seawater.

Further, the sea water concentration (salt content) C _M on the supply side of the reverse osmosis membrane cartridge 4 is approximately determined by C _M ≈ (C ₀ + C ₂ ) / 2. The sea water concentration (salt content) C ₀ and the concentration sea water concentration (salt content) C ₂ may be the above approximate equations as long as the recovery rate Q ₁ / Q ₀ does not change significantly. Therefore, the sea water concentration (salt content) C ₀ and the concentrated sea water concentration (salt content) C ₂ of the seawater supplied to the reverse osmosis membrane cartridge 4 can be regarded as constants, particularly during normal operation of the apparatus.

Also, the π-C _M function unit 7-3 and the QH function unit 7-4 have the same vertical axis, and the supply pressure P _M of the reverse osmosis membrane cartridge 4 is the temporarily set discharge pressure P _0. The loss head PL1 due to the seawater conduit of the supply side high-pressure line 10 in the reverse osmosis membrane cartridge 4 is reduced. The dilute water pressure P ₁ of the reverse osmosis membrane cartridge 4 is substantially constant, and the solute (salt content) C ₁ of dilute water may be considered constant, so that the osmotic pressure π ₁ of dilute water may be constant. Therefore, the reverse osmotic pressure ΔP is
ΔP = (P _M −P ₁ ) − (π _M −π ₁ )
Is calculated. (This relationship is shown removed during [pi-C _M functional unit 7-3 and Q-H functional unit 7-4)

[Delta] P-Q ₁ functional section 7-2 [pi-C _M functional unit 7-3 and Q-H functional unit 7-4 and the scale of the vertical axis are equal, a reverse osmosis membrane dilute water cartridge 4 flow rate Q ₁ Is obtained by the following equation represented by a straight line 56.
Q ₁ = A _M KΔP (1)
(Where A _M is the area of the reverse osmosis membrane 4a, and ΔP is the pressure in the vicinity of the reverse osmosis membrane 4a exceeding the osmotic pressure π _{M of} seawater supplied to the reverse osmosis membrane cartridge 4)

The Q-H function unit 7-4 of the control device 7 has a pressure H on the vertical axis and a flow rate Q on the horizontal axis. The Q-H curve of the pump (as shown in detail in FIG. -H curves 53 and 53 'are combined QH curves of the high pressure pump (HP) 3 and the booster pump (BP) 6, and curves 51 are QH curves of the high pressure pump (HP) 3 and curves 52 and 52. 'Shows the Q-H curve of the booster pump (BP) 6) and the curve 57 of the dilute water flow rate Q ₁ of the reverse osmotic pressure cartridge 4 corresponding to the discharge pressure P ₀ to the reverse osmosis membrane cartridge 4 on the same scale. It is a figure.

A control processing procedure for controlling the supplied seawater flow rate Q ₀ supplied to the reverse osmosis membrane cartridge 4 by the control device 7 will be described. Here, the rotation speed of the high-pressure pump (HP) 3 is made constant, the discharge flow rate of the booster pump (BP) 6, that is, the rotation speed of the booster pump (BP) 6 is controlled, and the seawater supplied to the reverse osmosis membrane cartridge 4 This is a processing procedure for controlling the flow rate.

(Step ST1)
First, an ideal diluted water flow rate Q ₁ (= Q _S1 ) is set from the diluted water flow rate setting unit 21.

(Step ST2)
Next, the rotation speed N of the booster pump (BP) 6 is assumed. FIG. 3 is a diagram showing details of the QH function unit 7-4. Here, the QH curve when the flow rate control of the seawater supplied to the reverse osmosis membrane cartridge 4 is performed by fixing the rotation speed of the high-pressure pump (HP) 3 and changing the rotation speed N of the booster pump (BP) 6. Is shown. As shown in the drawing, the QH curve (including the concentrated seawater line 13 side pressure) of the booster pump (BP) 6 is curved with respect to the QH curve 51 in which the rotation speed of the high pressure pump (HP) 3 is fixed. When changing from 52 to the curve 52 ′, the combined QH curve of the high pressure pump (HP) 3 and the booster pump (BP) 6 changes from the combined QH curve 53 to the combined QH curve 53 ′.

(Step ST3)
_Let the diluted water flow rate Q ₁ calculated by the above equation (1) be Q _1CALC .

(Step ST4)
The value of the set diluted water flow rate Q _S1 is compared with the calculated diluted water flow rate Q _1CALC . Then repeat steps ST2~ST4 as a loop when the error is large, and re-assuming the rotational speed N of the booster pump (BP) 6 returns to step ST2, the lean water flow rate Q _1CALC calculated lean water flow rate Q ₁ Repeat until the error is small. That, Q _1CALC which is obtained by the discharge pressure P ₀ which is assumed in step ST2 earlier, when it comes to Q _1CALC -Q _S1> 0, as to reduce the discharge pressure P ₀ of the re-assumption, Q _1CALC -Q _S1 < When it becomes 0, the rotation speed N of the booster pump (BP) 6 is changed so that the value of the re-assumed discharge pressure P ₀ is increased, and the QH curve is changed from the curve 52 to the curve 52 ′. The entire QH curve (combined QH curve) is changed from the curve 53 to the curve 53 ′, and the discharge pressure P ₀ is brought to a value such that the curve 57 becomes the set value Q _S1 . Further, by _bringing the discharge pressure P ₀ to the discharge pressure value P ₀₁ which becomes the maximum value Q _1max of the diluted water flow rate in the curve 57, the diluted water flow rate can be set to the maximum value Q _1max .

In order to set the discharge pressure P ₀ supplied to the reverse osmosis membrane cartridge 4 to the diluted water flow rate Q _S1 set for the curve 57, a specific control method is as follows. The number of rotations of the booster pump (BP) 6 is selected and output to the driver 24 (inverter here). The driver 24 controls the rotational speed of the electric motor 16 to control the rotational speed of the booster pump (BP) 6 and changes the rotational speed N so that the QH curve of the booster pump (BP) 6 changes from the curve 52 to the curve 52 ′. As a result, the entire QH curve relatively changes from the curve 53 to the curve 53 ′.

As described above, when the control device 7 sets the value of the dilute water flow rate Q ₁ , the relationship between the concentration of the supplied seawater and the osmotic pressure is fixed, so the combined Q− of the high pressure pump (HP) 3 and the booster pump (BP) 6. The H curve can be adjusted to the flow rate of diluted water arbitrarily set by changing the rotation speed of the booster pump (BP) 6. That relationship between the high pressure pump (HP) 3 and the booster pump (BP) operating point and lean water flow rate to Q ₁ 6 is uniquely determined. Further, when the set value of the diluted water flow rate Q ₁ is _matched with the maximum value Q _1max point of the diluted water flow rate in the curve 57 of the reverse osmosis membrane cartridge 4 (reverse osmosis membrane 4a), the diluted water flow rate at the maximum value Q _1max point. Is obtained.

  FIG. 4 is a diagram showing a configuration example of a positive displacement piston pump as an example of the positive displacement energy recovery device (ER) 5. The positive displacement piston pump 30 includes a control switching valve 31, a switching valve 32, and two energy recovery chambers 33 and 34. The concentrated seawater line 13 is connected to the inlet of the control switching valve 31, and the drainage line 14 is connected to the outlet. The supply line 9 is connected to the inlet of the switching valve 32, and the supply seawater bypass line 15 is connected to the outlet.

  In the positive displacement piston pump 30 having the above configuration, when the control switching valve 31 is switched as shown in FIG. 4A, the high-pressure reject (concentrated seawater) 103 from the concentrated seawater line 13 flows into the energy recovery chamber 33, While moving the piston 33a in the direction of arrow B, the seawater supplied through the supply line 9 and the switching valve 32 into the energy recovery chamber 33 is pressed by the piston 33a and rejected 103 (concentrated seawater). And is discharged to the supply seawater bypass line 15 through the switching valve 32. On the other hand, the seawater in the supply line 9 flows into the energy recovery chamber 34 that has transmitted the pressure energy to the supply seawater bypass line 15 through the switching valve 32, and the piston 34a is pressed and moved in the direction of arrow C. The rejected (concentrated seawater) 104 that has disappeared is discharged to the drain line 14.

  When the control switching valve 31 is switched as shown in FIG. 4B, the high-pressure reject (concentrated seawater) 103 from the concentrated seawater line 13 flows into the energy recovery chamber 34, and the piston 34a is pushed and moved in the direction of arrow F. At the same time, the seawater in the energy recovery chamber 34 is pressed by the piston 34 a and pressurized to substantially the same pressure as the reject (concentrated seawater) 103, passes through the switching valve 32, and is discharged to the supply seawater bypass line 15. . On the other hand, the seawater in the supply line 9 flows into the energy recovery chamber 33 through the switching valve 32 and pushes and moves the piston 33a in the direction of arrow E, and the rejected (concentrated seawater) 104 whose pressure has disappeared is discharged to the drainage line 14. Is done.

  As described above, pressure loss in the reverse osmosis membrane cartridge 4 and the concentrated seawater line 13, pressure loss in the control switching valve 31 and switching valve 32 of the positive displacement piston pump 30 which is the positive displacement energy recovery device (ER) 5, energy The pressure of seawater in the supply seawater bypass line 15 is lower than the pressure of seawater flowing into the reverse osmosis membrane cartridge 4 through the high pressure line 10 due to leakage loss between the recovery chambers 33 and 34 and the internal pistons 33a and 34a. . The booster pump 6 is provided to pressurize the seawater in the supply seawater bypass line 15 to compensate for this pressure loss and to merge with the seawater in the high-pressure line 10. Therefore, the booster pump 6 may be a pump having an electric capacity smaller than that of the high-pressure pump 3.

  In the seawater desalination apparatus having the above configuration, the desalination rate of the reverse osmosis membrane 4a of the reverse osmosis membrane cartridge 4 is predicted from membrane characteristics, that is, temperature, pressure, and permeate flow rate. Further, as a structural feature of the positive displacement energy recovery device (ER) 5, as in the positive displacement piston pump 30, a device for isolating the concentrated seawater and the supplied seawater has been devised, but the pistons 33 a, 34 a, etc. It is difficult to seal leaks completely and continuously due to element wear and the like. For water quality management, for example, a conductivity meter 40 is provided as a salinity detector on the dilute water side (demineralized water side) 12 of the reverse osmosis membrane cartridge 4 to monitor the salinity and demineralize the dilute water (demineralized water) 102. The rate is monitored. When the desalination rate is lower than the predicted value at the initial stage of installation where the influence of secular change is small, there is a high possibility of rapid increase due to a failure (leakage of concentrated seawater) in the positive displacement energy recovery device (ER) 5.

  In addition, as the auxiliary measurement, the supply line 9 and the supply seawater bypass line 15 are also provided with conductivity meters 41 and 42 as salinity detectors, and the salinity measured with the conductivity meter 40 on the demineralized water side as described in detail later. By comparing these, it is possible to grasp the leakage situation of the positive displacement energy recovery device (ER) 5. And when the desalination rate deviates from the predicted value beyond the specified value, the BP rotation speed selection unit 22-1 reduces the rotation speed of the booster pump (BP) 6 along with the light failure display, and the supply seawater bypass line 15 side Control to reduce the amount of water. Further, the deterioration of the membrane due to aging of the reverse osmosis membrane cartridge 4 (accumulation of deposits on the reverse osmosis membrane 4a and deterioration of membrane characteristics (desalting ability) with time) will be described in detail later. The cleaning time (or replacement time) of the reverse osmosis membrane 4a can be automatically set.

FIG. 5 shows a temperature sensor 43 provided in the high-pressure line 10, a conductivity meter 40 provided on the desalted water side of the reverse osmosis membrane cartridge 4, a conductivity meter 41 provided in the supply line 9, and a conductivity provided in the supply seawater bypass line 15. It is a figure which shows the processing flow for detecting the failure of positive displacement energy recovery apparatus (ER) and the deterioration of the reverse osmosis membrane 4a by the output of the rate meter 42. The recovery rate (%), salt permeation ratio (%), and desalination rate (%) of the reverse osmosis membrane cartridge 4 are expressed by the following equations.
Recovery rate (%) = {(Diluted water flow rate) / (Supply seawater flow rate)} × 100
Salt permeation ratio (%) = {(Dilute water solute (salt) concentration) / (Supply sea water solute (salt) concentration)} × 100
Desalination rate (%) = 100-salt permeation ratio In addition, the flow rate of the dilute water and the desalination rate of the reverse osmosis membrane change depending on the temperature as shown in FIG. Note that dilute water (demineralized water) flow rate and salt permeation ratio increase as the temperature rises.

In FIG. 5, the seawater detection temperature in the high pressure line 10 by the temperature sensor 43 and the pressures of the high pressure line 10 and the supply seawater bypass line 15 are measured by the pressure sensors 26 and 27 (step ST11). Next, with reference to the QH curves of the high pressure pump (HP) 3 and the booster pump (BP) 6 stored in the storage unit 23, the high pressure line 10 and the supply seawater bypass line 15 measured in the above step ST11. The flow rates of the high-pressure pump (HP) 3 and the booster pump (BP) 6 are calculated from the pressure (step ST12). Next, as shown in FIG. 6, the membrane characteristics (desalting rate vs. temperature / pressure) of the reverse osmosis membrane 4a of the reverse osmosis membrane cartridge 4 are obtained from previously stored data (step ST13), and the control device 7 The flow rate of each (pump discharge and dilute water) is assumed. Therefore, the solute (salt content) concentration C _CAL is calculated from the data of the membrane characteristics, seawater detection temperature, and each flow rate (step ST14). Next, the actual dilute water solute (salt) concentration C ₁ is calculated from the output of the conductivity meter 40 (step ST15). Subsequently, it is determined whether or not | C _CAL −C ₁ |> threshold (step ST16), and if No, it is determined normal (step ST17).

If yes, the solute (salt content) concentrations C _0-2 and C _0-1 of the seawater in the supply seawater bypass line 15 and the supply line 9 are measured by the outputs of the conductivity meter 41 and the conductivity meter 42 (steps). ST18) Subsequently, it is determined whether or not | C _0-2 -C _0-1 |> threshold and (C _0-2 -C _0-1 )> 0 (step ST19). The membrane deterioration of the reverse osmosis membrane 4a of the cartridge 4 is determined (step ST20), and if Yes, the failure of the volume energy recovery device (ER) is determined (step ST21). The membrane deterioration of the reverse osmosis membrane 4a of the reverse osmosis membrane cartridge 4 and the failure of the volume energy recovery device (ER) are warned by a display device or alarm device (not shown), and if the reverse osmosis membrane 4a is deteriorated, the membrane is washed. (Or replacement in some cases), and in the case of a failure of the positive displacement energy recovery device (ER) 5, repair or replacement, and the following measures are taken.

(Measures in case of failure of positive displacement energy recovery device (ER))
When the high-pressure pump (HP) 3 has a design specification that can cope with a decrease in the flow rate of the booster pump (BP) 6 minutes, the valve V3 provided on the discharge side of the booster pump (BP) 6 is closed, by opening the valve V5 of concentrated seawater drainage bypass line 17, the control target value to Q ₁ lean water flow rate (demineralized amount) as shown in FIG. 7, the positive-displacement energy recovery apparatus (ER) 5 is determined to failure Lower to Q ₂ at time T1. That is, as indicated by the broken line in FIG. 8, the lift curve (HP + BP) of the high pressure pump (HP) 3 + booster pump (BP) 6 (as a whole system) was operated as indicated by the solid line. Switch to the operation of the lift curve (HP) of only the pump (HP) 3.

  In order to back up the high pressure pump (HP) 3, when a backup high pressure pump (BHP) 28 driven by an electric motor 29 is provided as shown in FIG. At the time T1 when it is determined that the valve V3 is closed, the backup high-pressure pump (BHP) 28 is operated as shown in FIG. That is, from the operation of the lift curve of the high-pressure pump (HP) 3 shown by the solid line in FIG. 10 (operating state by the high-pressure pump (HP) 3 with the valve V3 closed and the valve V5 opened), the high-pressure pump (HP) shown by the dotted line 3+ The operation of the head curve (HP + BHP) of the backup high-pressure pump (BHP) 28 is assumed.

  The amount of leakage from the positive displacement energy recovery device (ER) 5 can be estimated from the error in the desalination rate. Accordingly, in the positive displacement energy recovery device (ER) 5, if the relationship between the leakage amount and the wear amount of the sealing portion is stored in a database in advance, the replacement and repair timing of the positive displacement energy recovery device (ER) 5 can be predicted. Become.

  In the above-described embodiment, the case where the rotation speed of the electric motor 16, that is, the rotation speed of the booster pump (BP) 6 is controlled by the driver (here, the inverter) 24 is shown. However, as shown in FIG. , A flow adjustment valve (flow control valve) V1 provided in the concentrated seawater line 13, a flow adjustment valve (flow control valve) V2 provided in the drainage line 14, and a flow adjustment valve provided in the supply seawater bypass line 15. The flow rate may be controlled by controlling the opening degree of the valve (flow rate control valve) V3 and the flow rate adjusting valve (flow rate control valve) V4 provided in the high pressure line 10. Further, as shown in FIG. 13, a concentrated seawater drain bypass line 17 that drains the concentrated seawater flowing through the concentrated seawater line 13 by bypassing the volumetric energy recovery device (ER) 5 is provided. A valve (flow rate control valve) V5 for adjusting the flow rate may be provided, and the concentrated seawater flow rate introduced into the positive displacement energy recovery device (ER) 5 may be controlled by controlling the opening degree of the valve V5 with the driver 24. .

Further, as shown in FIG. 14, the rotational speed of the electric motor 8 that drives the high-pressure pump (HP) 3 is controlled by a driver (here, an inverter) 24, and the flow rate of seawater discharged from the high-pressure pump (HP) 3 (reverse) The flow rate of seawater supplied to the osmotic membrane cartridge 4 may be controlled. As shown in FIG. 15, when the OH curve of the high pressure pump (HP) 3 is changed from 51 to 51 ′ with respect to the QH curve 52 of the booster pump (BP) 6, the booster pump (BP) 6 and the high pressure pump (HP) 3 have a combined OH curve of 53 to 53 ′. By adjusting the set value of the target diluted water flow rate (target demineralized water flow rate) Q ₁ to the maximum value Q _1MAX of the diluted water of the curve 57 of the reverse osmosis membrane cartridge 4 a of the reverse osmosis membrane cartridge 4, the reverse osmosis membrane cartridge 4 is It can be operated at the maximum diluted water point of the reverse osmosis membrane 4a.

  In the above example, the temperature sensor 43 provided in the high-pressure line 10, the conductivity meter 40 provided on the desalted water side of the reverse osmosis membrane cartridge 4, and the supply line 9 are used as state detection means for detecting the state of each part of the membrane separation device. An example is shown in which the output of the conductivity meter 41 provided in the above and the conductivity meter 42 provided in the supply seawater bypass line 15 are monitored to detect a failure of the volumetric energy recovery device (ER) and membrane deterioration of the reverse osmosis membrane 4a. However, the state detection means is not limited to this, and a sensor for monitoring other parts of the membrane separation apparatus may be provided, and the state of each part may be detected from the output. Further, the failure countermeasure control means does not correspond to the failure of the positive displacement energy recovery device (ER) and the membrane deterioration of the reverse osmosis membrane 4a, but may be able to cope with the failure of other parts.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible. In the above embodiment, the positive displacement piston pump 30 has been described as the positive displacement energy recovery device (ER) 5, but the positive displacement energy recovery device (ER) 5 is not limited to the positive displacement piston pump. The pressure exchange apparatus currently disclosed by Table 2004-500502 gazette may be sufficient. In other words, any device that transmits energy in a limited space may be used.

It is a schematic diagram which shows the 1st aspect of the seawater desalination apparatus which concerns on this invention. It is a functional block diagram of the control apparatus of the seawater desalination apparatus which concerns on this invention. It is a figure which shows the QH curve of a high pressure pump (HP) and a booster pump (BP). It is a figure which shows the structural example of a positive displacement piston pump as a positive displacement energy recovery apparatus. It is a figure which shows the processing flow of degradation of a reverse osmosis membrane and failure determination of a volume type energy recovery apparatus. It is a figure which shows the relationship between the diluted water flow rate of a reverse osmosis membrane, a desalination rate, and temperature. It is a figure for demonstrating the countermeasure example of the failure of a positive displacement energy recovery apparatus. It is a figure for demonstrating the countermeasure example of the failure of a positive displacement energy recovery apparatus. It is a figure for demonstrating the countermeasure example of the failure of a positive displacement energy recovery apparatus. It is a figure for demonstrating the countermeasure example of the failure of a positive displacement energy recovery apparatus. It is a schematic diagram which shows the 2nd aspect of the seawater desalination apparatus which concerns on this invention. It is a schematic diagram which shows the 3rd aspect of the seawater desalination apparatus which concerns on this invention. It is a schematic diagram which shows the 4th aspect of the seawater desalination apparatus which concerns on this invention. It is a schematic diagram which shows the 5th aspect of the seawater desalination apparatus which concerns on this invention. It is a figure which shows the QH curve of a high pressure pump (HP) and a booster pump (BP).

Explanation of symbols

1 Intake pump 2 Pretreatment device 3 High pressure pump (HP)
4 Reverse Osmosis Membrane Cartridge 4a Reverse Osmosis Membrane 5 Volumetric Energy Recovery Device (ER)
6 Booster pump (BP)
7 controller 7-1 D _W -T functional unit 7-2 [Delta] P-Q ₁ functional section 7-3 π-C _M functional unit 7-4 Q-H functional unit 8 electric motor 9 supply line 10 high pressure line 11 pressure chamber 12 Dilute water side 13 Concentrated seawater line 14 Drainage line 15 Supply seawater bypass line 16 Electric motor 17 Concentrated water bypass line 19 Pressure sensor 20 Pump discharge flow rate calculation unit 21 Diluted water flow rate setting unit 22-1 BP rotation speed selection unit 22-2 Valve opening selection unit 22-3 Valve opening selection unit 22-4 HP rotation speed selection unit 23 Storage unit 24 Drivers 26, 27 Pressure sensor 28 High-pressure pump for backup (BHP)
29 Electric motor (for BHP)
30 Volumetric Piston Pump 31 Control Switching Valve 32 Switching Valve 33, 34 Energy Recovery Chamber 33a, 34a Piston 40-42 Conductivity Meter 43 Temperature Sensor C ₀ Sea Water Solute (Salt) Concentration C ₁ Dilute Water Solute (Salt) Concentration C ₂ concentrated seawater solute (salt) concentration C _M seawater solute (salt) concentration P ₀ discharge pressure (supply seawater pressure)
P ₁ reverse osmosis membrane lean water side of the cartridge 4 (demineralized water side) pressure P ₂ reverse osmosis membrane feed side pressure Q ₀ supplied seawater flow rate of the concentrated seawater side pressure of the cartridge 4 P _M reverse osmosis membrane cartridge 4 (the pump delivery rate) , Composite discharge flow rate Q ₁ Dilute water flow rate (Demineralized water flow rate)
Q ₂ Concentrated seawater flow rate Q _1MAX Maximum dilute water flow rate C _0-1 Solute (salt content) concentration of high pressure line 10 _0-2 Solute (salt content) concentration of supply seawater bypass line 15 P _0-1 High pressure pump (HP) 3 Discharge pressure P ₀ -2 booster pump (BP) 6 discharge pressure Q _0-1 high pressure pump (HP) 3 discharge flow rate Q ₀ -2 booster pump (BP) 6 discharge flow rate T seawater temperature V1-V5 valve ( Flow control valve)

Claims (8)

A high pressure pump for pressurizing the supplied raw water, a reverse osmosis membrane cartridge, and energy recovery means disposed downstream of the reverse osmosis membrane cartridge on the concentrated water side, and the high pressure raw water pressurized by the high pressure pump is In a membrane separator that is introduced into a osmotic membrane cartridge and separated into dilute water and concentrated water,
Concentrated water is introduced from the reverse osmosis membrane cartridge as the energy recovery means, and a positive displacement energy recovery device that pressurizes a part of the supplied raw water is used.
A bypass pipe for joining the raw water pressurized by the positive displacement energy recovery device to the high-pressure raw water flowing through the high-pressure line connecting the high-pressure pump and the reverse osmosis membrane cartridge;
A booster pump which is provided in the middle of the bypass pipe and pressurizes raw water flowing in the bypass pipe;
Raw water flow rate control means for controlling the raw water flow rate supplied to the reverse osmosis membrane cartridge;
State detection means for detecting the state of each part of the membrane separation device;
A membrane separation apparatus comprising a failure handling control unit corresponding to a failure of each part detected by the state detection unit. The membrane separation apparatus according to claim 1,
The raw water flow rate control means controls the flow rate of raw water supplied to the reverse osmosis membrane cartridge by controlling the number of rotations of a high-pressure pump and / or a booster pump. The membrane separation apparatus according to claim 1,
From the high-pressure line, the bypass line, a concentration line that leads the concentrated water discharged from the reverse osmosis membrane cartridge to the positive displacement energy recovery device, a drainage line that drains the concentrated water from the positive displacement energy recovery device, and the concentration line A flow rate control valve is provided in each concentrated water bypass line that drains concentrated water by bypassing the positive displacement energy recovery device,
The membrane separation apparatus, wherein the raw water flow rate control means controls the flow rate of raw water supplied to the reverse osmosis membrane cartridge by controlling at least one of the flow rate control valves. The membrane separation apparatus according to any one of claims 1 to 3,
A first concentration sensor for detecting the concentration of the diluted water, a second sensor for detecting the concentration of the concentrated water flowing through the bypass pipe, a third concentration sensor for detecting the concentration of the supply raw water, and the temperature of the raw water A sensor for detecting
The membrane separation device characterized in that the state detection means has a function of detecting a failure of the positive displacement energy recovery device and / or a reverse osmosis membrane deterioration of the reverse osmosis membrane cartridge from the output of each sensor. The membrane separator according to claim 4,
A concentrated water bypass line for draining the concentrated water introduced from the reverse osmosis membrane cartridge into the positive displacement energy recovery device by bypassing the positive displacement energy recovery device; and a flow control valve provided in the concentrated water bypass line; Provided,
When the state detection means detects a failure of the positive displacement energy recovery device, the malfunction countermeasure control means opens a flow control valve provided in the concentrated water bypass line to drain the concentrated water. Separation device. The membrane separator according to claim 5,
When the state detection means detects a failure of the positive displacement energy recovery device, the failure countermeasure control means stops the booster pump and supplies raw water to the reverse osmosis membrane cartridge only by the operation of the high pressure pump. A membrane separator characterized by the above. The membrane separator according to claim 5,
A backup pump for backing up the high-pressure pump is provided,
When the state detection unit detects a failure of the positive displacement energy recovery device, the failure countermeasure control unit stops the booster pump, operates the backup pump, and operates the high-pressure pump and the backup pump. A membrane separation device characterized by supplying raw water to a reverse osmosis membrane cartridge. A high pressure pump for pressurizing the supplied raw water, a reverse osmosis membrane cartridge, and energy recovery means disposed downstream of the reverse osmosis membrane cartridge on the concentrated water side, and the high pressure raw water pressurized by the high pressure pump is In the operation management method of the membrane separation device introduced into the osmosis membrane cartridge and separated into dilute water and concentrated water,
While using a positive displacement energy recovery device as the energy recovery means, a booster pump is provided,
Concentrated water is introduced from the reverse osmosis membrane cartridge into the volumetric energy recovery device, a part of the supplied raw water is pressurized, the pressurized raw water is pressurized by the booster pump, and the pressurized raw water is The high pressure raw water flowing through the connecting pipe connecting the high pressure pump and the reverse osmosis membrane cartridge is merged, and the flow rate of the raw water supplied to the reverse osmosis membrane cartridge is controlled,
The membrane is monitored by a state detection means for detecting the state of each part of the membrane separation device, and when the state detection means detects a failure of each part, the failure response control means controls each part according to the failure. Operation management method of separation device.

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