Seawater desalination system and energy recovery apparatus

Patent metadata

Field	Value
Publication number	US-9957169-B2
Application number	US-201414774011-A
Country	US
Kind code	B2
Filing date	Feb 25, 2014
Priority date	Mar 11, 2013
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

An energy recovery apparatus usable in a seawater desalination system. The energy recovery apparatus includes a plurality of chambers to pressurize the seawater by pressure energy of the concentrated seawater by supply and discharging the concentrated seawater and the seawater, a first flowmeter for integrating a flow rate of the seawater or the concentrated seawater which flows into the chamber, a second flowmeter for integrating a flow rate of the seawater or the concentrated seawater discharged from the chamber, a switching valve in each of the chambers to switch the inflow and the discharge of the concentrated seawater, and a controller to control the respective switching valves of the chambers on the basis of integrated flow rate of the chamber obtained from the flow rate of the flowmeter. The controller inputs a single input signal to the respective switching valves of the chambers to control the respective switching valves.

First claim

The invention claimed is:

1. An energy recovery apparatus for exchanging pressure energy between concentrated seawater discharged from a reverse-osmosis membrane-separation apparatus and a part of seawater to be treated by the reverse-osmosis membrane-separation apparatus in a seawater desalination system for producing fresh water from the seawater by supplying the seawater to the reverse-osmosis membrane-separation apparatus to separate the seawater into fresh water and concentrated seawater, the energy recovery apparatus comprising:
a plurality of chambers configured to pressurize the seawater by pressure energy of the concentrated seawater by supply and discharging the concentrated seawater and the seawater;
a first flowmeter used for integrating a flow rate of the seawater or the concentrated seawater which flows into the chamber;
a second flowmeter used for integrating a flow rate of the seawater or the concentrated seawater discharged from the chamber;
at least one switching valve provided in each of the plurality of chambers and configured to switch the inflow of the concentrated seawater to the chamber and the discharge of the concentrated seawater from the chamber; and
a controller configured to control the respective switching valves of the plurality of chambers on the basis of integrated flow rate of the chamber, the integrated flow rate of the chamber being obtained on the basis of the flow rate of the first flowmeter and/or the second flowmeter;
wherein the controller controls the respective switching valves of the plurality of chambers by a trapezoidal waveform signal whose signal value varies from −100% to +100% with time, valve openings of the respective switching valves being determined by inputting signal values of the trapezoidal waveform signal to predetermined formulas of the relationship between signal values of the trapezoidal waveform signal and valve openings of the respective switching valves.

2. The energy recovery apparatus according to claim 1 , wherein valve opening and switching time of each of the switching valves can be controlled by the trapezoidal waveform signal.

3. The energy recovery apparatus according to claim 1 , wherein the valve opening of each of the respective switching valves is set so as to vary in response to the input signal based on a predetermined setting value.

4. The energy recovery apparatus according to claim 1 , wherein the controller controls the switching valve so as to perform switching of the switching valve of the chamber when an integrated flow rate of the chamber by the first flowmeter or the second flowmeter reaches a predetermined value.

5. The energy recovery apparatus according to claim 4 , wherein switching of the switching valve is performed by a value calculated from a predetermined ratio of the actual volume of the chamber.

6. The energy recovery apparatus according to claim 1 , wherein the controller controls the flow rate of the concentrated seawater discharged from the chamber by comparing an integrated value of an inflow amount of the concentrated seawater to the chamber and an integrated value of a discharge amount of the concentrated seawater from the chamber.

7. The energy recovery apparatus according to claim 1 , wherein the controller controls the switching valve so that an integrated value of the inflow amount of the seawater to the chamber is equal to or larger than an integrated value of the inflow amount of the concentrated seawater to the chamber.

8. The energy recovery apparatus according to claim 1 , wherein the controller controls the respective switching valves so as to include a process for discharging the pressurized seawater from the plurality of chambers simultaneously.

9. An energy recovery apparatus for exchanging pressure energy between concentrated seawater discharged from a reverse-osmosis membrane-separation apparatus and a part of seawater to be treated by the reverse-osmosis membrane-separation apparatus in a seawater desalination system for producing fresh water from the seawater by supplying the seawater to the reverse-osmosis membrane-separation apparatus to separate the seawater into fresh water and concentrated seawater, the energy recovery apparatus comprising:
a plurality of chambers configured to pressurize the seawater by pressure energy of the concentrated seawater by supply and discharging the concentrated seawater and the seawater;
at least one switching valve provided in each of the plurality of chambers and configured to switch the inflow of the concentrated seawater to the chamber and the discharge of the concentrated seawater from the chamber; and
a controller configured to control the respective switching valves of the plurality of chambers by a trapezoidal waveform signal whose signal value varies from −100% to +100% with time, valve openings of the respective switching valves being determined by inputting signal values of the trapezoidal waveform signal to predetermined formulas of the relationship between signal values of the trapezoidal waveform signal and valve openings of the respective switching valves.

10. A seawater desalination system for producing fresh water from seawater by supplying the seawater to a reverse-osmosis membrane-separation apparatus to separate the seawater into fresh water and concentrated seawater, the seawater desalination system comprising:
an energy recovery apparatus according to claim 1 for exchanging pressure energy between the concentrated seawater discharged from the reverse-osmosis membrane-separation apparatus and a part of the seawater to be treated by the reverse-osmosis membrane-separation apparatus.

Assignees

• Ebara Corp

Inventors

• Shinoda Masao
• Takita Shigeo

Classifications

• B01D61/025

  Reverse osmosis; Hyperfiltration · CPC title

• B01D2313/18

  Specific valves · CPC title

• Y02W10/30

  Wastewater or sewage treatment systems using renewable energies · CPC title

• B01D61/06

  Energy recovery · CPC title

• C02F2209/40

  Liquid flow rate · CPC title