Introduction of Energy Recovery Device used in SWRO

Introduction of Energy Recovery Device used in SWRO

Wu LimingTianjin University

literature

1 Waste energy recovery in seawater reverse osmosis desalination plants.(Part 1)A.M.K El-ghonemy 1 November 2012

2 Waste energy recovery in seawater reverse osmosis desalination plants.(Part 2: Case study)A.M.K El-ghonemy 27 April 2012

3 Pressure Exchange Apparatus With Integral PumpPatent NO:us 7 214 315 B2Date of Patent:May 8.2007

4 Axial piston MachinePatent NO:us 7 988 428 B1Date of patent:Aug, 2,2011 1/11

Osmosis process is the tendency of water to flow through semi-permeable membrane into a more concentrated solution

Reverse osmosis is a form of filtration in which the filter is a semi-permeable membrane that allows water to pass through, but not salt.

Reverse osmosis

Concentrated Solution

membrane Pure water

Concentrated Solution

membrane Pure water

Pressure

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The osmotic pressure of typical seawater is around 26 bar, and this is the pressure that the pump must overcome in order to reverse the flow . In practice , in order to achieve a generous flow of freshwater, a significantly higher pressure as 50-80 bar is used.Concentrated

Solution

membranePure water

Pressure

Pressure

Pressure needed for RO

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Advantages: 1 Half of the energy needed by the thermal process. 2 Modularity of reverse osmosis units, Simplicity of operation3 Lower environment impact. Indeed, reverse osmosis process accounted for 59% of contracted desalination capacity as of September 2008, having grown at a rate of 17% per year since 1990.

Why SWRO

能量回收装置

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Electricity consumption is a main cost of SWRO. The RO reject stream contains most of the energy supplied to the seawater feed by the high pressure pump. Recovery of this energy and its utilization reduce the overall energy demand of SWRO.

Why ERD

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1980 1990 2000 2010

turbocharger Rotary exchanger

Piston exchanger Pelton turbine

Francis turbine

1 Energy recovery turbine (ERT) with Pelton wheels.2 Turbocharger, a turbine driven centrifugal pump, mostly applied.3 Pressure exchanger(PX),using a rotating ceramic rotor and allows the feed and concentrate to have direct contact.4 Dual work exchanger energy recovery(DWEER), an isobaric device that used a piston and valves to separate seawater feed and the concentrated return.

History of ERD

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3-in-1 design High pressure pumpPressure exchangerElectric motor

Advantages:Efficiency: Reduced energy cost by 60% compared to SWRO plants with no ERD.Simple: Fewer parts, easier installation. Fewer meters. Reduced fittings and pipes.Reliable: Such product integrates the booster pump to eliminate sealing issues.

A new product of Danfoss

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Possible design

Pressure exchanger

Electric motor

Booster pump

Pressure is transformed in the cylinder channels

Two impellers, connected to a motor through a shaft ,are used to raise the pressure of the fluid

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4-in-1 designHigh pressure pump Pressure exchangerBooster pump Electric motor

Advantages:Reduced operation costsHigh energy efficiencyReliable and safe Easy of system adaptation

A new product of KSB

High pressure pump

Pressure exchangerBooster pump

Electric motor

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Possible design

A plunger-pump similar structure is united into the pressure exchanger, energy to raise the pressure from both the energy of electric motor and the rejected water.

Axial piston

Swash plateshaft

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Theory of plunger pump

Swash plate

Axial piston

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Thank you for your attention