Isobaric Energy Recovery Devices in Reverse and Forward Osmosis ProcessesRichard L. Stover, Ph.D.

OUTLINE

• Energy recovery in seawater reverse osmosis• ERD development milestones• Currently available devices• Design challenges• Next generation devices• New applications

Performance analysis in companion presentation by Dr. Bill Andrews

Energy Recovery in Seawater Desalination

Positive Displacement (isobaric)

Centrifugal (turbine)

Source: Energy Recovery, Inc.

ERD Development Milestones

• First isobaric device – Cheng filed 1965

• Rotary isobaric device – Hashemi filed 1966

• Large chamber device for SWRO – Taylor filed 1973

• RO-isobaric device for lifeboats – Keefer filed 1978

• Pressure exchanger device – Hauge filed 1987

• Ionics Dyprex – late-1980s

• Spool valve for work exchanger – Shumway filed 1996

• Integrated Pump-ERD “Clark Pump” - Permar filed 1996

Currently Available Devices

KSB Saltec

Vari-RO IPER

AquaLyngRecuperator

Spectra Clark pump

Flowserve DWEER ERI

PX

Danfoss iSave

How an Isobaric Energy Recovery Device Works

Low PressureSeawater

Enters the Plant

High PressurePump

High PressureSeawater

High Pressure

Low PressureReject Stream

Low Pressure Fresh WaterExits the Plant

High PressureReject Stream

Booster Pump

Seawater

Membrane

Turbine /Generator

Membranes

High Pressure Pump

Fresh Water

Salt WaterDilute Water

Pressure Exchanger Applications

Basic Osmotic Power

Pressure Exchanger Applications

PX Device

Turbine /Generator

Membranes

CirculationPump

Fresh Water

Salt WaterDilute Water

Efficient Osmotic Power

Pressure Exchanger Applications

PX Device

Membranes

CirculationPump

High Pressure

Pump

Fresh Water

Salt Water

Concentrated Salt Water

Reverse Osmosis Desalination

Design Challenges

• High-pressure seal– leakage and integrity

• Brine-feedwater barrier• Pulsations / vibration

– endured and transmitted• Noise• Operational control

– process transients and multi-device arrays• Unit capacity• Corrosion• Capital costs and maintenance

Next Generation Devices

• ERI PX Titan and PX-300 devices– bigger

Sources: Energy Recovery, Inc. and EPO

Next Generation Devices

• Flowserve/Calder ROVA– smoother

Sources: WDR and EPO

New Applications

Source: Energy Recovery, Inc.

New Applications

Source: Energy Recovery, Inc.

New Applications

Source: Energy Recovery, Inc.

New Applications

Source: Energy Recovery, Inc.

New Applications

Source: Energy Recovery, Inc.

Isobaric ERD

Turbine /Generator

Membranes

CirculationPump

Fresh Water

Salt Water Dilute Water

• Osmotic Power

New Applications

Source: Energy Recovery, Inc.

• Osmotic Heat Engine

Isobaric ERD

Turbine /Generator

FO MembranesCirc.Pump

Working Fluid

Draw Solution

Dilute Water

Regenerator

Q in

Q out

Thank you!