JP5762041B2 - Combined desalination system - Google Patents

Description

  The present invention provides a first water treatment system for filtering a first raw water having a high salinity concentration, such as seawater, brackish water, brine, etc., using a reverse osmosis membrane device, and a first salt treatment having a lower salinity concentration than the first raw water. And a second water treatment system for filtering the raw water of No. 2 using a reverse osmosis membrane device, and in particular, a non-permeate discharged from the reverse osmosis membrane device of the second water treatment system The present invention relates to a technology that utilizes the hydraulic energy of water.

  In Patent Document 1, in a seawater desalination apparatus that desalinates seawater by filtration using a reverse osmosis membrane apparatus, for example, wastewater containing organic substances represented by sewage (hereinafter referred to as “organic wastewater”) is disclosed. Normally, biological wastewater that has been biologically treated and discharged into the ocean or river is mixed with seawater taken by the seawater desalination unit, and the salinity of the treated water in the seawater desalination unit is mixed. By reducing (diluting) the seawater as it is, and feeding the treated water diluted with the above-mentioned salinity to the reverse osmosis membrane device of the seawater desalination unit, the pumping pump (in the “high pressure pump” in this specification) The technology for reducing the required driving force is described.

  Patent Document 2 discloses that in a desalination system using a reverse osmosis membrane device, the pressure of non-permeated water in the reverse osmosis membrane device is recovered by a turbocharger to pressurize water to be treated in the reverse osmosis membrane device. The technology to be used is described.

Japanese Patent No. 4,481,345 JP 2001-149932 A

  However, in the technique described in Patent Document 1, the pressure when the reverse osmosis membrane device is used in the water treatment process of organic wastewater is higher than the pressure when the reverse osmosis membrane device is used in the water treatment process of the seawater desalination device. Low pressure. And, the non-permeated water discharged from the reverse osmosis membrane device in the water treatment process of the organic wastewater is only mixed with the seawater taken directly, and the salinity concentration is lowered than the seawater. Since the energy of the non-permeated water from the reverse osmosis membrane device in the wastewater treatment process is relatively low pressure, it is not used at all and is wasted.

  This invention solves the above-mentioned conventional subject, and it aims at providing the composite desalination system which can utilize effectively the energy of the non-permeated water of the reverse osmosis membrane apparatus in a composite desalination system.

In order to solve the above-described problem, a composite desalination system according to a first aspect of the present invention includes a first water treatment system that performs filtration treatment on first raw water having a high salinity using a first reverse osmosis membrane device, A second water treatment system for filtering a second raw water having a lower salinity concentration than the first raw water using a second reverse osmosis membrane device, wherein the first water treatment system The first stage of the first reverse osmosis membrane apparatus is a first stage filtration apparatus for filtering the treated water containing the first raw water taken, and the first stage supplies the treated water under pressure to the first stage filtration apparatus. The first pump is driven by the water pressure of the non-permeate water discharged from the second reverse osmosis membrane device of the second water treatment system, and the non-permeate driving the first pump The water is mixed with the first raw water via the back pressure valve to be treated water.

Since the salt concentration of the water to be treated in the second water treatment system is lower than the salt concentration of the water to be treated in the first water treatment system, the water pressure of the non-permeated water in the second reverse osmosis membrane device is naturally The water pressure is considerably lower than the water pressure of the non-permeated water of the reverse osmosis membrane device 1. However, the required pressure increase degree of the first pump that pressurizes and supplies the water to be treated including the first raw water to the pre-stage filtration device is lower than the pressure required for the water to be treated to the first reverse osmosis membrane device. . Accordingly, the first pump is driven by the water pressure of the non-permeated water discharged from the second reverse osmosis membrane device of the second water treatment system, whereby the second reverse osmosis of the second water treatment system. The water pressure of non-permeated water discharged from the membrane device can be used effectively.
In addition, the non-permeated water that has driven the first pump is mixed with the first raw water of the first water treatment system, so that the salt concentration of the first raw water taken by the first water treatment system is diluted. Thus, the required pressure increase degree of the pump that supplies the first reverse osmosis membrane device with pressurized water to be treated can be reduced.

The composite desalination system of 2nd invention is the 1st water treatment system which filters the 1st raw | natural water of high salinity concentration using a 1st reverse osmosis membrane apparatus, and low salinity rather than the 1st raw | natural water A second water treatment system for filtering the second raw water having a concentration using a second reverse osmosis membrane device, wherein the first water treatment system takes in the first raw water. And a first raw water tank for storing the taken first raw water, and the third pump is discharged from the second reverse osmosis membrane device of the second water treatment system. The non-permeated water that is driven by the water pressure of the non-permeated water and drives the third pump is supplied to the first raw water tank via the back pressure valve .

Since the salt concentration of the water to be treated in the second water treatment system is lower than the salt concentration of the water to be treated in the first water treatment system, the water pressure of the non-permeated water in the second reverse osmosis membrane device is naturally The water pressure is considerably lower than the water pressure of the non-permeated water of the reverse osmosis membrane device 1. However, the required pressure increase degree of the third pump for supplying the first raw water to the first raw water tank is lower than the pressure required for the water to be treated to the first reverse osmosis membrane device. Accordingly, the third pump is driven by the water pressure of the non-permeated water discharged from the second reverse osmosis membrane device of the second water treatment system, whereby the second reverse osmosis of the second water treatment system. The water pressure of non-permeated water discharged from the membrane device can be used effectively.
In addition, the non-permeated water that has driven the third pump is supplied to the first raw water tank of the first water treatment system, so that the salinity concentration of the first raw water taken by the first water treatment system is diluted. In addition, it is possible to reduce the required degree of pressure increase of the pump that supplies the treated water to the first reverse osmosis membrane device under pressure.

  ADVANTAGE OF THE INVENTION According to this invention, the composite desalination system which can utilize effectively the energy of the non-permeated water of the reverse osmosis membrane apparatus in a composite desalination system can be provided.

It is a schematic block diagram of the composite desalination system of basic embodiment. It is a schematic block diagram of the composite desalination system which concerns on 1st Embodiment. It is a schematic block diagram of the composite desalination system which concerns on 2nd Embodiment. It is a schematic block diagram of the composite desalination system which concerns on 3rd and 4th embodiment.

  Below, the composite desalination system which concerns on embodiment of this invention is demonstrated in detail, referring a figure.

<< Compound desalination system of basic embodiment >>
First, a combined desalination system 100 according to a basic embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic block diagram of the composite desalination system of the basic embodiment.
This composite desalination system 100 is assumed to be installed in a coastal zone, in the vicinity of a saltwater lake, in the vicinity of a brackish water zone, and the like.
The combined desalination system 100 is a wastewater (second raw water) A (hereinafter simply referred to as “drainage A”) having a lower salinity than seawater, brackish water, brine, and the like, such as industrial wastewater and urban wastewater. A wastewater treatment system (second water treatment system) 1 for wastewater treatment so that it can be reused as middle water other than drinking water such as industrial water (referred to as “permeate water B” or “product water B”); Reuse water (first raw water) D with relatively high salinity, such as seawater, brackish water, brine, etc., as medium water (referred to as “permeate E” or “product water E”) other than drinking water such as industrial water A seawater desalination treatment system (first water treatment system) 3 that performs purification treatment as possible, and a control device 6 that controls the operation of pumps and valves included in the wastewater treatment system 1 and the seawater desalination treatment system 3. It is configured.
In the following, “water D having a relatively high salinity such as seawater, brackish water, brine, etc.” is hereinafter referred to as “seawater D” as representatively and as described above in the meaning of “seawater D”. This is referred to as “seawater desalination treatment system 3”.

(Configuration of wastewater treatment system 1)
First, a schematic configuration of the wastewater treatment system 1 will be described with reference to FIG. The drainage A contains organic substances and is referred to as a water treatment device (hereinafter referred to as “MBR water treatment device 11”) using, for example, a membrane separation activated sludge method (MBR) from the drainage water intake pipe 51. Simply “MBR”) and primary processing. The treated water primarily treated in the MBR water treatment apparatus 11 is once introduced from the MBR water treatment apparatus 11 to the treated water tank 13 serving as a buffer for the flow of the treated water through the pipe 52 by the transfer pump 12. It is stored. Further, the water to be treated stored in the treated water tank 13 is sucked by the supply pump 14 through the pipe 53 and supplied to the high pressure pump 15, and the pressure is increased by the high pressure pump 15. The reverse osmosis membrane device) 16 is supplied to the supply port 16a of the water to be treated.

The low-pressure reverse osmosis membrane device 16 has a configuration in which, for example, a plurality of membrane module units as described in FIGS. 3 and 4 of JP 2001-149932 A are arranged in parallel.
The treated water supplied with pressure from the supply port 16a passes through the reverse osmosis membrane (RO membrane: Reverse Osmosis Membrane) in the low-pressure reverse osmosis membrane device 16 and purified water. It is separated into non-permeated water C which is treated water that has not permeated the membrane. The permeated water B is supplied from the permeation port 16b through the pipe 54 to the use according to the external water quality level as the produced water B.

The non-permeated water C is supplied from a drain port 16c of the low pressure reverse osmosis membrane device 16 through a pipe 56 to a back pressure valve 18 provided in the middle and supplied to a water intake tank (first raw water tank) 32 described later. Is done. The TDS (Total Dissolubed Solids) of the concentrated non-permeated water C of the wastewater treatment system 1 is about 1,200 mg / liter, and the TDS of seawater D is about 30,000 mg / liter. Therefore, the concentration is extremely low. Therefore, the low-pressure reverse osmosis membrane device 16 described above is operated at a pressure of 0.8 to 1.5 MPa. Incidentally, the range of the operating pressure is to increase the operating pressure in order to obtain the required flow rate of the permeated water B when the contamination of the reverse osmosis membrane of the low pressure reverse osmosis membrane device 16 increases.
Therefore, the pressure of the non-permeate water C is about 0.8 to 1.5 MPa. Then, this pressure is released by the back pressure valve 18 described above.
An ultrafiltration device may be used instead of the MBR water treatment device 11 of the wastewater treatment system 1.
The pipe 56 may have a function of collecting the pressure of the non-permeated water C as energy when the non-permeated water C of the low-pressure reverse osmosis membrane device 16 is introduced into the intake tank 32. The configuration will be described in detail in the first to fourth embodiments.

(Seawater desalination treatment system 3)
Next, a schematic configuration of the seawater desalination treatment system 3 will be described with reference to FIG. Seawater D is sucked from the water intake pipe 81 by the water intake pump 31, supplied to the water intake tank 32 by the water intake pipe 82, and stored. As described above, since the non-permeate water C of the wastewater treatment system 1 is supplied to the water intake tank 32 through the pipe 56, the seawater D and the non-permeate water C are mixed in the water intake tank 32, and the salt concentration is lower than seawater. It becomes treated water. That is, the value of TDS is also lower than that of seawater D.
The treated water collected in the water intake tank 32 is supplied to the pretreatment filtration device (pre-stage filtration device) 34 with a predetermined pressure by the filtration pump 33 through the pipe 83.
Examples of the pretreatment filtration device 34 include a UF device using an ultrafiltration membrane (UF (Ultra Filtration) membrane), an MF device using a microfiltration membrane (MF (Micro Filtration) membrane), and a sand filtration device. Either is fine. Incidentally, in FIG. 1, “UF” representing a UF device is typically displayed on the pretreatment filtration device 34.
When a UF device is taken as an example of the pretreatment filtration device 34, it is generally operated at 50 to 150 kPa.

The treated water filtered by the pretreatment filtration device 34 is temporarily stored in the treated water tank 35 serving as a buffer for the flow of the treated water through the pipe 84. Then, the water to be treated stored in the treated water tank 35 is sucked by the supply pump 36 through the pipe 85 and supplied to the high pressure pump 37, and the pressure is increased to, for example, about 3.5 to 6 MPa by the high pressure pump 37. The seawater reverse osmosis membrane device (first reverse osmosis membrane device) 38 is supplied to the supply port 38a of the water to be treated. The seawater reverse osmosis membrane device 38 has, for example, a configuration in which a plurality of membrane module units as described in FIGS. 3 and 4 of JP-A-2001-149932 are arranged in parallel. However, since it is operated at a higher pressure than the low-pressure reverse osmosis membrane device 16, the material of the reverse osmosis membrane of the seawater reverse osmosis membrane device 38 has a performance capable of withstanding a higher pressure.
By the way, this operating pressure is obtained in order to obtain the required flow rate of the permeated water E when the TDS value of the treated water supplied to the reverse osmosis membrane of the seawater reverse osmosis membrane device 38 and the contamination increase. Increase.

  The treated water supplied with pressure from the supply port 38a is the permeated water E that has been purified by permeating the reverse osmosis membrane in the seawater reverse osmosis membrane device 38, and the treated water that has not permeated the reverse osmosis membrane. It is separated into non-permeated water G which is water. The permeated water E is supplied from the permeate port 38b through the pipe 87 to the use according to the external water quality level as the produced water E.

The non-permeated water G has the operating pressure of the seawater reverse osmosis membrane device 38 and is supplied from the drain port 38c to the high pressure supply port 39d of the pressurization side end portion 39b described later in the energy recovery device 39 through the pipe 89. After the pressure is directly exchanged with the water to be treated supplied from the supply pump 36, the flow rate is adjusted by the back pressure valve 40 provided in the middle of the pipe 90 from the discharge port 39e of the pressurization side end portion 39b and discharged. The
This non-permeated water G is seawater, brackish water, or brackish water in which salinity is concentrated.
In this basic embodiment, the energy recovery device 39 is of a direct pressure exchange type, and is mainly a rotor portion 39a, a pressure side end portion 39b, and a pressure side to be rotated at a predetermined rotational speed by a motor (not shown). This is an apparatus of a known technique that is configured by an end portion 39c.

  A pipe 91 is branched from the pipe 85 at a branch point P1 of the pipe 85 between the supply pump 36 and the high-pressure pump 37, and a part of the low-pressure treated water supplied by the supply pump 36 is added to the energy recovery device 39. It is supplied to the supply port 39g of the compression side end portion 39c. And the to-be-processed water supplied to the supply port 39g is pressurized by the direct exchange of the pressure with the non-permeated water G from the seawater reverse osmosis membrane apparatus 38, Then, from the discharge port 39f of the to-be-pressurized side end part 39c It is further supplied to a booster pump 41 provided in the middle of the pipe 92. The booster pump 41 boosts the water to be treated which has been pressurized by the energy recovery device 39 to the same pressure as the high pressure pump 37, and is supplied from the high pressure pump 37 at the junction P <b> 2 of the pipe 86 on the downstream side of the high pressure pump 37. The treated water and the treated water from the pipe 92 are merged, and the treated water is supplied to the supply port 38 a of the seawater reverse osmosis membrane device 38.

  Thus, since the non-permeated water G of the seawater reverse osmosis membrane device 38 has an extremely high pressure, the energy is recovered and reused as energy for supplying the water to be treated to the seawater reverse osmosis membrane device 38. However, the power cost can be saved by reducing the capacity of the high-pressure pump 37. Moreover, the salt concentration can be reduced by mixing the non-permeated water C of the waste water treatment system 1 with the seawater D, and the pressure increase required for the high-pressure pump 37 is about 6 MPa in the case of only seawater. When the non-permeated water C and the seawater D are made substantially the same amount and diluted, it can be lowered to about 3.5 MPa. As a result, the power cost can be reduced accordingly. That is, the operating pressure of the seawater reverse osmosis membrane device 38 is higher than the operating pressure of the low pressure reverse osmosis membrane device 16, and the energy of the non-permeated water G of the seawater reverse osmosis membrane device 38 is recovered and the seawater reverse osmosis is recovered. The operating pressure itself of the membrane device 38 can also be reduced.

  The transfer pump 12, the supply pump 14, the high pressure pump 15, the intake pump 31, the filtration pump 33, the supply pump 36, the high pressure pump 37, the booster pump 41, the rotor 39a of the energy recovery device 39, and the like are not shown. An inverter device (not shown) that is connected to the rotating shaft of the motor and is configured integrally and supplies power to the drive motor is installed as a field board or is integrally attached to the drive motor. And the control apparatus 6 is a structure which controls rotation of a drive motor via an inverter.

(Control device 6)
Next, an outline of the control of the control device 6 in the basic embodiment will be described.
The control device 6 is composed of, for example, a plurality of control units 60, 61, 63, and each of the control units 60, 61, 63 has a CPU board, an input / output interface board, and the like on which a CPU, ROM, RAM, etc., not shown are mounted. It is equipped with. The control unit 60 controls the entire composite desalination system 100, the control unit 61 controls the wastewater treatment system 1, and the control unit 63 controls the seawater desalination treatment system 3. Therefore, the control unit 60 is connected to the control units 61 and 63 so as to communicate with each other.
And the control unit 61 contains the flow volume control part (not shown) which adjusts the opening degree of the back pressure valve 18 as a function part, and adjusts the flow volume of the non-permeate water C. FIG.

  The required flow rate commands C1 and C2 of the production water B and the production water E in the combined desalination system 100 are input to the control unit 60 of the control device 6 from the outside. Then, the control unit 60, for example, according to the required flow rate command C1, the waste water flow rate supplied to the waste water treatment system 1 (flow rate detected by the flow rate sensor S1 described later) and the flow rate of the permeate B (flow rate described later). Based on the flow rate detected by the sensor S6), the target flow rate of the permeated water B of the wastewater treatment system 1 is set to cause the control unit 61 to control the wastewater treatment system 1, and in accordance with the required flow rate command C2, seawater A target flow rate of the permeated water E of the desalination treatment system 3 is calculated, and the control unit 63 controls the seawater desalination treatment system 3.

  For this purpose, the drainage intake pipe 51 is provided with a flow rate sensor S1 for detecting the flow rate of the drainage A, and the pipe 54 is provided with a flow rate sensor S6 for detecting the flow rate of the permeated water B. The flow rate and the flow rate of the permeated water B are input to the control unit 60. The pipe 87 is provided with a flow rate sensor S20 that detects the flow rate of the permeated water E, and the flow rate of the permeated water E is input to the control unit 60 via the control unit 63.

  For example, the MBR water treatment apparatus 11 is provided with a water level sensor S2, and the control unit 61 controls the start and stop of the transfer pump 12 based on the water level signal from the water level sensor S2. The treated water tank 13 is provided with, for example, a water level sensor S3, and the control unit 61 receives the water level signal from the water level sensor S3 and the pressure signal from the pressure sensor S4 provided in the pipe 53 on the suction side of the high-pressure pump 15. Based on this, the start and stop control of the supply pump 14 and the rotation speed during operation of the supply pump 14 are controlled. The control of the rotation speed of the supply pump 14 based on the pressure signal from the pressure sensor S4 is for giving a predetermined suction pressure to the high-pressure pump 15.

Further, the control unit 61 has a high pressure so that the flow rate becomes the target flow rate of the permeated water B input from the control unit 60 based on the flow rate signal of the permeated water B from the flow rate sensor S6 provided in the pipe 54. The rotational speed of the pump 15 is adjusted. Then, the rotational speed of the high-pressure pump 15 is feedback-controlled so that the flow rate signal becomes constant based on the flow rate signal from the flow rate sensor S5 provided in the piping 53 on the discharge side of the high-pressure pump 15 at that time.
The feedback control of the rotational speed of the high-pressure pump 15 in the control unit 61 is appropriately corrected based on the deviation between the flow rate signal of the permeated water B and the target flow rate of the permeated water B.

  The pipe 56 is provided with a flow rate sensor S7 for detecting the flow rate of the non-permeate water C of the low-pressure reverse osmosis membrane device 16, and the flow rate control unit of the control unit 61 controls the flow rate of the non-permeate water C. The opening degree of the back pressure valve 18 is adjusted based on the flow rate signal from the flow rate sensor S7 so that the flow rate becomes a constant rate with respect to the flow rate indicated by the water flow rate sensor S5.

The intake pipe 82 is provided with a flow rate sensor S11, and the intake tank 32 is provided with a water level sensor S12. The control unit 63 controls the start and stop of the water intake pump 31 based on the water level signal from the water level sensor S12, and the seawater D according to the flow rate of the non-permeated water C discharged from the waste water treatment system 1 to the water intake tank 32. Is set, and the rotational speed of the water intake pump 31 is controlled based on the flow rate signal from the flow rate sensor S11.
For example, when the flow rate of the non-permeate water C and the intake flow rate of the seawater D are substantially the same, and the non-permeate water C is mixed with the seawater D in the intake tank 32 to reduce the salinity, the seawater reverse osmosis membrane device 38 The operating pressure can be maintained at about 3.5 to 4 MPa.

  The control unit 63 controls the start and stop of the filtration pump 33 based on the water level signal from the water level sensor S14 provided in the treated water tank 35, and the flow rate signal from the flow rate sensor S13 provided in the pipe 84. Based on the above, the rotational speed of the filtration pump 33 is controlled to a predetermined rotational speed, the water to be treated in the water intake tank 32 is pumped to the pretreatment filtration device 34 at a predetermined pressure, subjected to a primary treatment, and the treated water subjected to the primary treatment Is stored in the treated water tank 35.

  Further, the control unit 63 controls the start and stop of the supply pump 36 based on the pressure signal from the pressure sensor S15 provided in the suction-side pipe 85 of the high-pressure pump 37, and the rotation speed during operation of the supply pump 36. To control. The control of the rotation speed of the supply pump 36 based on the pressure signal from the pressure sensor S15 is to give a predetermined suction pressure to the high-pressure pump 37.

Further, the control unit 63 supplies the flow rate of the permeated water E input from the control unit 60 based on the flow rate signal of the permeated water E from the flow rate sensor S20 provided in the pipe 87. The rotational speeds of the pump 36, the high pressure pump 37, and the booster pump 41 are adjusted. Then, the rotational speeds of the high pressure pump 37 and the booster pump 41 so that the flow rate signals are constant based on the flow rate signal from the flow rate sensor S16 provided in the piping 86 on the discharge side of the high pressure pump 37 and the booster pump 41 at that time. Feedback control.
Note that the feedback control of the rotational speeds of the high-pressure pump 37 and the booster pump 41 in the control unit 63 is corrected as appropriate based on the deviation between the flow rate signal of the permeate E and the target flow rate of the permeate E.

  The pipe 89 is provided with a flow rate sensor S19 for detecting the flow rate of the non-permeate water G of the seawater reverse osmosis membrane device 38, and the control unit 63 determines that the flow rate of the non-permeate water G is the flow rate sensor S16 of the water to be treated. The opening degree of the back pressure valve 40 is adjusted so that the flow rate becomes a constant rate with respect to the indicated flow rate.

  Thus, in the composite desalination system 100 of the basic embodiment, the non-permeated water C of the low-pressure reverse osmosis membrane device 16 discharged from the waste water treatment system 1 is mixed with the seawater D that has been taken in, and the seawater desalination treatment system 3 By using the water to be treated, the salinity of the water to be treated in the seawater desalination treatment system 3 can be reduced to about half, and the operating pressure for operating the seawater reverse osmosis membrane device 38 is treated only with 100% seawater. The pressure can be greatly reduced as compared with about 6 MPa required in some cases, and the power cost can be reduced.

<< First Embodiment >>
Next, the composite desalination system 100A according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic block diagram of the composite desalination system according to the first embodiment. The basic configuration of the composite desalination system 100A of the present embodiment is substantially the same as the composite desalination system 100 of the basic embodiment shown in FIG. 1, but the control device 6 in the composite desalination system 100 is controlled by The point which the apparatus 6 controls the flow regulating valve 19 mentioned later, and as shown in FIG. 2, unlike the basic embodiment shown in FIG. A difference is that a turbine pump (first pump) 33 </ b> A is used instead of the filtration pump 33.
In the present embodiment, the flow rate sensor S13 provided in the pipe 84 in the basic embodiment of FIG. 1 is provided in the pipe 83B described later.

Therefore, one end of the pipe 56 is connected to the drain port 16c of the low pressure reverse osmosis membrane device 16, and the other end is connected to the pressurized water inlet 33c of the turbine section 33a of the turbine pump 33A. One end of the pipe 57 is connected to the discharge port 33d of the turbine section 33a of the turbine pump 33A, and the other end is connected to the intake tank 32 via the back pressure valve 18.
One end of the pipe 83A is connected to the water intake tank 32, and the other end is connected to the suction port 33e of the pump portion 33b of the turbine pump 33A. One end of a pipe 83B is connected to the discharge port 33f of the pump portion 33b of the turbine pump 33A, and the other end is connected to the pretreatment filtration device 34.
Furthermore, one end of the return pipe 83C is connected at the branch point P5 of the pipe 83B, and the other end is connected to the water intake tank 32 via the flow rate adjusting valve 19.
The non-permeated water C of the low pressure reverse osmosis membrane device 16 is driven to rotate the turbine built in the turbine section 33a of the turbine pump 33A, and is discharged to the water intake tank 32 through the back pressure valve 18. Then, the turbine rotates and drives the pump impeller built in the pump unit 33b, and sucks in the water to be treated in which the seawater (first raw water) D and the non-permeated water C in the water intake tank 32 are mixed. For example, the pressure is increased to about 150 kPa and supplied to the pretreatment filtration device 34 via the pipe 83B.

And the function of the control units 60 and 61 of the control apparatus 6 in this embodiment is the same as the function of the control units 60 and 61 of the control apparatus 6 in the composite desalination system 100 of the basic embodiment. The function of the control unit 63 of the control device 6 in this embodiment is substantially the same as the function of the control unit 63 of the control device 6 in the combined desalination system 100, but does not have the function of controlling the filtration pump 33, and the flow rate It has a function of adjusting the opening of the adjusting valve 19.
The same components as those of the composite desalination system 100 are denoted by the same reference numerals and redundant description is omitted, and redundant description of the same control function in the control device 6 of the basic embodiment is also omitted.

  A flow rate control unit (not shown) as a functional unit of the control unit 61 in the present embodiment controls the flow rate of the non-permeated water C of the low pressure reverse osmosis membrane device 16. The turbine pump 33A is a turbine inlet pressure applied by the non-permeated water C of the low-pressure reverse osmosis membrane device 16 at the pressurized water inlet 33c {in Table 1, "turbine inlet pressure (pressurized pressure of non-permeated water)" "Indication" increases as the turbine inlet flow rate (liters / min) {displays "turbine inlet flow rate (non-permeate water flow rate)" in the second column from the left in Table 1}. When the turbine inlet flow rate with respect to the value of each turbine inlet pressure of the non-permeated water C of the low pressure reverse osmosis membrane device 16 is normalized to 100% as shown in the third and subsequent columns from the left, the pump portion of the turbine pump 33A The discharge flow rate (%) of the water to be treated corresponding to the discharge pressure (kPa) of the water to be treated from the discharge port 33f of 33b is larger than the flow rate (%) of the turbine inlet.

Since the opening degree of the back pressure valve 18 is controlled by the above-described flow rate control unit of the control unit 61 in order to control the flow rate of the non-permeated water C of the low pressure reverse osmosis membrane device 16, the discharge of the pump unit 33b of the turbine pump 33A The flow rate is automatically determined by the water pressure and flow rate of the non-permeate water C. In order to accurately adjust the flow rate of the water to be treated supplied to the pretreatment filtration device 34 at the rotational speed of the turbine pump 33A, the control unit 63 has a flow rate control unit (not shown) as a functional unit. When the supply amount of the water to be treated by the turbine pump 33A to the pretreatment filtration device 34 is too large, the opening degree of the flow rate adjustment valve 19 is adjusted based on the flow rate signal from the flow rate sensor S13, and the return pipe 83C is set. Then, excess water to be treated is returned to the water tank 32.
Therefore, when the intake amount of the seawater D of the seawater desalination system 3 is about 0.5 times the flow rate of the non-permeate water C of the low pressure reverse osmosis membrane device 16 as in the desalination system 100 of the basic embodiment, filtration is performed. The pump 33 is not required, and the combined desalination system 100A can reduce the driving power cost accordingly.

<< Second Embodiment >>
Next, the composite desalination system 100B which concerns on the 2nd Embodiment of this invention is demonstrated, referring FIG. FIG. 3 is a schematic block diagram of a composite desalination system according to the second embodiment. The difference between the composite desalination system 100B of this embodiment and the composite desalination system 100A is that the control unit 63 of the control device 6 controls an auxiliary filtration pump (second pump) 33B described later, and FIG. As shown, the pipe 83D is further connected from the water intake tank 32 to a junction P6 with the pipe 83B, and the auxiliary filtration pump 33B is provided in the pipe 83D.
The control device 6 includes a control unit 60, a control unit 61, and a control unit 63, as in the first embodiment.

  The function of the control unit 63 is basically the same as that of the control unit 63 in the first embodiment, but the flow rate control unit (not shown) as the functional unit is pretreatment of the water to be treated by the turbine pump 33A. When the supply amount to the filtration device 34 is too large, the opening degree of the flow rate adjustment valve 19 is adjusted based on the flow rate signal from the flow rate sensor S13, and excess water to be treated is taken into the water tank 32 via the return pipe 83C. return. Conversely, the flow rate control unit of the control unit 63 activates the auxiliary filtration pump 33B when the supply amount of the water to be treated to the pretreatment filtration device 34 by the turbine pump 33A is small, and the turbine pump 33A and the auxiliary filtration The rotational speed of a motor (not shown) that drives the auxiliary filtration pump 33B is controlled based on the flow rate signal of the flow rate sensor S13 so that the total amount of water to be treated with the pump 33B becomes a required flow rate.

  Incidentally, the pump capacity of the auxiliary filtration pump 33B is smaller than the pump capacity of the filtration pump 33 in the basic embodiment, and the power cost when operating the auxiliary filtration pump 33B is lower than that in the basic embodiment.

The above-described flow rate control unit of the control unit 63 performs the start and stop of the auxiliary filtration pump 33B, the control of the rotation speed of the auxiliary filtration pump 33B during operation, and the opening adjustment of the flow rate adjustment valve 19 at the junction P6. Although it is based on the flow rate signal from the flow rate sensor S13 provided in the downstream pipe 83B, it is not limited thereto.
Instead of the flow rate sensor S13, the flow rate sensor S13A is provided in the pipe 83B upstream from the branch point P5, and the flow rate sensor S13B is provided in the pipe 83D downstream of the auxiliary filtration pump 33B. The flow rate of the water to be treated supplied to the pretreatment filtration device 34 may be determined and controlled based on the flow rate signals from the flow rate sensors S13A and 13B. That is, when the flow rate indicated by the flow rate sensor S13A is equal to or higher than the required flow rate, the auxiliary filtration pump 33B is stopped, and the flow rate of the water to be treated supplied to the pretreatment filtration device 34 by adjusting the opening degree of the flow rate adjustment valve 19. To control. Conversely, when the flow rate indicated by the flow rate sensor S13A is less than the required flow rate, the opening of the flow rate adjustment valve 19 is fully closed and the auxiliary filtration pump 33B is activated. Then, the rotational speed of the auxiliary filtration pump 33B is controlled so that the total value of the flow rate indicated by the flow rate sensor S13A and the flow rate indicated by the flow rate sensor S13B becomes a required flow rate, and the water to be treated supplied to the pretreatment filtration device 34. Control the flow rate.

  According to this embodiment, when the flow rate of the water to be treated from the water intake tank 32 supplied by the turbine pump 33 </ b> A driven by the non-permeate water C is larger than the required flow rate to be supplied to the pretreatment filtration device 34. Even in the case where the amount is small, the above-described flow rate control unit of the control unit 63 can flexibly control the target flow rate of the production water E.

<< Third and Fourth Embodiments >>
(Third embodiment)
Next, a composite desalination system 100C according to a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a schematic block diagram of a combined desalination system according to the third and fourth embodiments.
The basic configuration of the composite desalination system 100C of the third embodiment is substantially the same as the composite desalination system 100 of the basic embodiment, but the control unit 63 of the control device 6 is different from the composite desalination system 100. In contrast to the basic embodiment shown in FIG. 1, the seawater D is taken into the water tank 32 as shown in FIG. 3 in that a turbine pump (third pump) 33 </ b> A described later is controlled instead of the water intake pump 31. A difference is that a turbine pump 33 </ b> A is used instead of the intake pump 31.
In the present embodiment, the flow rate sensor S13 provided in the pipe 84 in the basic embodiment of FIG. 1 is provided in the pipe 83 on the discharge side of the filtration pump 33.

Therefore, as shown in FIG. 4, one end of the pipe 56 is connected to the drain port 16c of the low pressure reverse osmosis membrane device 16, and the other end is connected to the pressurized water inlet 33c of the turbine part 33a of the turbine pump 33A. One end of the pipe 57 is connected to the discharge port 33d of the turbine section 33a of the turbine pump 33A, and the other end is connected to the intake tank 32 via the back pressure valve 18.
Further, the intake pipe 81 is connected to the suction port 33e of the pump part 33b of the turbine pump 33A. One end of the intake pipe 82C is connected to the discharge port 33f of the pump portion 33b of the turbine pump 33A, and the other end is connected to the intake tank 32.
The non-permeated water C of the low pressure reverse osmosis membrane device 16 is driven to rotate the turbine built in the turbine section 33a of the turbine pump 33A, and is discharged to the water intake tank 32 through the back pressure valve 18. The turbine rotates and drives a pump impeller built in the pump unit 33b, sucks seawater (first raw water) D through the intake pipe 81, and supplies the seawater tank 32 through the intake pipe 82C. To do.

And the function of the control apparatus 6 is as substantially the same as the function of the control apparatus 6 in the composite desalination system 100 of basic embodiment, and has the control unit 60, the control unit 61, and the control unit 63.
The same components as those in the composite desalination system 100 are denoted by the same reference numerals and redundant description is omitted, and redundant description of the same control functions as those of the control device 6 in the basic embodiment of the control device 6 in this embodiment is also omitted. .

The flow rate control unit (not shown) as a functional unit of the control unit 61 has the same function as the flow rate control unit (not shown) of the control unit 61 in the basic embodiment, and the non-permeated water of the low pressure reverse osmosis membrane device 16. The flow rate of C is controlled. Then, the turbine pump 33A has a turbine inlet flow rate (liter / min) of the non-permeate water C of the low pressure reverse osmosis membrane device 16 in accordance with an increase in the turbine inlet pressure of the non-permeate water C of the low pressure reverse osmosis membrane device 16 at the pressurized water inlet 33c. However, as shown in Table 1, the “characteristics of the discharge pressure of the treated water and the discharge flow rate of the treated water” shown in the third and subsequent columns from the left in Table 1 is “the discharge pressure of the seawater”. And the characteristics of the discharge flow rate of seawater ”) When the turbine inlet flow rate relative to the value of each turbine inlet pressure of the non-permeated water C of the low pressure reverse osmosis membrane device 16 is normalized to 100%, the pump portion 33b of the turbine pump 33A The discharge flow rate (%) of seawater corresponding to the discharge pressure (kPa) of seawater from the discharge port 33f is larger than the turbine inlet flow rate (%) of the non-permeated water C.
When the turbine inlet flow rate with respect to the value of each turbine inlet pressure is normalized to 100%, the discharge flow rate (%) of seawater D corresponding to the discharge pressure (kPa) of seawater D from the discharge port 33f of the pump part 33b of the turbine pump 33A ) Is larger than the turbine inlet flow rate (%) of the non-permeated water C of the low pressure reverse osmosis membrane device 16.

Since the opening degree of the back pressure valve 18 is controlled by a flow rate control unit (not shown) as a functional unit of the control unit 61 in order to control the flow rate of the non-permeated water C of the low pressure reverse osmosis membrane device 16, the turbine pump The discharge flow rate of the 33A pump unit 33b is automatically determined by the water pressure and flow rate of the non-permeate water C. Therefore, as a countermeasure when the seawater D supplied to the intake tank 32 by the turbine pump 33A is excessively taken, the intake tank 32 is provided with an overflow port (not shown), and the seawater D is taken in by the turbine pump 33A. Excess water is discharged from the seawater D.
Therefore, the water intake pump 31 is not required unlike the composite desalination system 100 of the basic embodiment, and the composite desalination system 100C can reduce the driving force cost by that amount.

  Incidentally, the function of the control unit 63 is basically the same as that of the control unit 63 in the basic embodiment, but the control unit 63 receives the intake amount of the seawater D based on the water level signals from the flow rate sensor S11 and the water level sensor S12. It does not have a function to control.

(Fourth embodiment)
Next, a composite desalination system 100D according to a fourth embodiment of the present invention will be described with reference to FIG. The difference from the combined desalination system 100C is that the control unit 63 of the control device 6 controls the auxiliary intake pump (fourth pump) 31A described later, and further from the intake pipe 81 as shown by the broken line in FIG. The intake pipe 81D is branched. The intake pipe 81D is connected to the suction port of the auxiliary intake pump 31A, and further, the intake pipe 82D is connected to the discharge port of the auxiliary intake pump 31A, and the intake tank 32 is connected. The flow rate sensor S35 is provided as indicated by the broken line in FIG. 4, the intake flow rate of the seawater D is detected, and the flow rate signal is input to the control device 6.
The control device 6 includes a control unit 60, a control unit 61, and a control unit 63, as in the third embodiment.

  The function of the control unit 63 is basically the same as that of the control unit 63 in the third embodiment, but the intake amount of the seawater D is based on the water level sensor S12 and the flow rate sensor S35 as in the control unit 63 in the basic embodiment. Have a function to control. Then, the flow rate control unit as the functional unit of the control unit 63 activates the auxiliary intake pump 31A when the intake amount of the seawater D to the intake tank 32 by the turbine pump 33A indicated by the flow rate sensor S35 is small, and the turbine pump 33A. And the auxiliary intake pump 31A, the rotational speed of a motor (not shown) that drives the auxiliary intake pump 31A is controlled based on the flow rate signal of the flow sensor S35 so that the total intake amount of the seawater D becomes the required intake amount.

  Incidentally, the pump capacity of the auxiliary intake pump 31A is smaller than the pump capacity of the intake pump 31 in the basic embodiment, and the power cost when operating the auxiliary intake pump 31A is lower than in the basic embodiment.

  According to this embodiment, even when the intake flow rate of the seawater D supplied to the intake tank 32 by the turbine pump 33A driven by the non-permeate water C is smaller than the required flow rate, the above-described flow rate control of the control unit 63 is performed. The intake amount of seawater D can be controlled by the section, and the target flow rate of the production water E can be achieved.

  As described above, according to the first to fourth embodiments, the relatively low pressure of 0.8 to 1.5 MPa that the non-permeated water C of the wastewater treatment system 1 has is recovered to drive the turbine pump 33A. Since it is used as energy, it is possible to provide the composite desalination systems 100A to 100D with a lower power cost than in the past.

In the first to fourth embodiments, the direct pressure exchange type is described as the energy recovery device 39 in FIGS. 2 to 4, and the booster pump 41 is combined in the subsequent stage, but this is limited to that. It is not a thing. The turbocharger pump may be driven by non-permeate water G. In this case, the pipe 89 and the pipe 90 are connected to the turbine part (drive part) inlet and outlet of the turbocharger pump, respectively, and the downstream side of the pipe 86 is connected to the pump part inlet of the turbocharger pump. Is connected to the supply port 38a by piping. Even in such a format, the pressure of the non-permeated water G can be recovered.
Incidentally, in that case, the pipes 91 and 92 and the booster pump 41 are unnecessary.

Moreover, although the 1st-4th embodiment demonstrated the example which introduces and mixes the non-permeated water C of the low pressure reverse osmosis membrane apparatus 16 in the water intake tank 32, it is not limited to it.
In the first and second embodiments, the most downstream end of the pipe 57 is directly connected to the intake pipe 82, and the non-permeated water C and the seawater D of the low-pressure reverse osmosis membrane device 16 are mixed in the pipe 82 to be covered. It may be treated water.
In the third and fourth embodiments, the most downstream end of the pipe 57 is directly connected to the downstream side of the flow rate sensor S35 of the pipe 81 on the suction side of the turbine pump 33A or the auxiliary intake pump 31A. The non-permeated water C and the seawater D of the low-pressure reverse osmosis membrane device 16 may be mixed to be treated water.

  In the basic embodiment and the first to fourth embodiments described above, the production water B and the production water E are supplied to the outside according to the respective water quality levels, but the production water B and the production water E are mixed. Then, it may be supplied to the outside.

1 Wastewater treatment system (second water treatment system)
3 Seawater desalination treatment system (first water treatment system)
6 Control device 11 MBR water treatment device 12 Transfer pump 13 Treated water tank 14 Supply pump 15 High pressure pump 16 Low pressure reverse osmosis membrane device (second reverse osmosis membrane device)
16c Drain port 18 Back pressure valve 19 Flow control valve 31 Intake pump 31A Auxiliary intake pump (fourth pump)
32 Intake tank (first raw water tank)
33 Filtration pump 33A Turbine pump (first pump, third pump)
33B Auxiliary filtration pump (second pump)
34 Pretreatment filtration device (pre-filtration device)
35 treated water tank 36 supply pump 37 high pressure pump 38 seawater reverse osmosis membrane device (first reverse osmosis membrane device)
39 Pressure Exchanger 40 Back Pressure Valve 41 Booster Pump 60 Control Unit 61 Control Unit 63 Control Unit 81, 81D, 82, 82C, 82D Intake Pipe 83C Return Pipe 100,100A, 100B, 100C, 100D Combined Desalination System A Drainage (No. 2 raw water)
D Seawater (first raw water)

Claims (7)

A first water treatment system that filters the first raw water having a high salinity concentration using the first reverse osmosis membrane device, and a second raw water having a lower salinity than the first raw water, A second desalination system that performs filtration using a reverse osmosis membrane device, and a composite desalination system comprising:
The first water treatment system is
In the previous stage of the first reverse osmosis membrane device, a pre-stage filtration device that performs a filtration treatment of treated water containing the first raw water taken, and
A first pump that pressurizes and supplies the treated water to the pre-stage filtration device;
Have
The first pump is driven by the water pressure of non-permeate water discharged from the second reverse osmosis membrane device of the second water treatment system, and the non-permeate water driving the first pump is: A composite desalination system, wherein the treated water is mixed with the first raw water through a back pressure valve. The first water treatment system is
A first raw water tank for storing the taken first raw water;
2. The composite desalination according to claim 1, wherein the non-permeate water that has driven the first pump is mixed with the first raw water in the first raw water tank to be treated water. system. The first water treatment system is
3. The composite fresh water according to claim 2, further comprising a second pump that pressurizes and supplies the water to be treated in the first raw water tank to the pre-stage filtration device in parallel with the first pump. System. The first water treatment system is
The composite desalination system according to any one of claims 1 to 3, further comprising a flow rate adjustment valve that adjusts a flow rate of the water to be treated supplied to the upstream filtration device. The first water treatment system is
A flow rate adjusting valve for adjusting the flow rate of the water to be treated supplied to the pre-stage filtration device;
4. The composite according to claim 2 , wherein the flow rate adjustment valve is provided in a return pipe that connects the treated water supply port side of the pre-stage filtration device and the first raw water tank. 5. Desalination system. A first water treatment system that filters the first raw water having a high salinity concentration using the first reverse osmosis membrane device, and a second raw water having a lower salinity than the first raw water, A second desalination system that performs filtration using a reverse osmosis membrane device, and a composite desalination system comprising:
The first water treatment system is
A third pump for taking the first raw water;
A first raw water tank for storing the taken first raw water;
Have
The third pump is driven by the water pressure of non-permeated water discharged from the second reverse osmosis membrane device of the second water treatment system, and the non-permeated water driving the third pump is A composite desalination system, characterized in that it is supplied to the first raw water tank via a pressure valve. The first water treatment system is
The composite desalination system according to claim 6, further comprising a fourth pump that takes the first raw water and sends it to the first raw water tank in parallel with the third pump.

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