CaribDA 2016 Conference & Exposition · Julen Cabero, PhD SUEZ Treatment Solutions, SAU. Title:...

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CaribDA 2016 Conference & Exposition“Developing and Affording New Water Sources”

31st May – 3rd June 2016 in Trinidad

Regulation of double stage SWRO plant after improving the energy consumption using ERI technology. Case study: Las

Americas SWRO plant, Canary Islands

Julen Cabero, PhDSUEZ Treatment Solutions, SAU

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INTRODUCTION

3 GRAPHICS THAT SHOW THE EVOLUTION OF ENERGYEFFICIENCY IN DESALITATION PLANTS IN THE LAST 40 YEARS

� Evolution of the Technology

� Evolution of the Energy Recovery Devices in SWRO Plants

� Evolution of the Energy consumption

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Evolution of the desalinationtechnology

Figure 2: Capacity of installed desalted water by technology (2015) [*][*] Global Water Intelligence/IDA

Figure 1: Capacity of installed desalted water: Thermal vs membrane

processes (1980 – 2013) ) [*]

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Evolution of the Energy Recovery Devices in RO

1970 1980 1990 2000 2010 2015

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Evolution of SEC (Kwh/m3)

Figure 3: Evolution of the Specific Energy Consumption in seawater desalination plants (1970-2015)

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Description of Las Americas SWRO plant

Evolution of the installation from 1998 until 2015

� Increase the flowrate

� Improvement of the Energy Efficiency

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Location

Canary Islands, SpainLas Americas SWRO plant

30.000 m3/d

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Evolution of the Energy Efficiency in Las Americas SWRO plant

1998 Production: 10.000 m3/d(2 racks x 5.000 with Francis turbine. One stage of RO)

2000 Extension 1 - Production: 20.000 m3/d(4 racks x 5.000 with Francis turbine. One stage of RO)

2004 Extension 2 - Production: 30.000 m3/d(4 racks x 7.500 with pelton turbine. 2 stages of RO)

2015 Increase the Energy efficiency with new energy recovery devices system - 30.000 m3/d

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2015 -Revampingof the plant

The main modifications has been:

� Motors with more electrical efficiency

� Installation of frequency converters in the booster pumps

� Design and installation of a new energy recovery system based in ERI technology

TargetReduction of Energy Consumption: > 0,35 Kwh/m3

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From PELTON turbine

To ERI system

High pressure side

Low pressure side

Evolution of the Energy Efficiency device in Las Americas SWRO

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RO Building –Before: with Pelton turbines

1st Stage RO racks

High pressure pumps with pelton turbines

2nd Stage RO racks

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RO Building –After : with ERI

1st Stage RO racks

New area:� ERI devices,� Booster pumps� HPPs� instrumentation� regulating valves� modified piping

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Evolution of the Energy Efficiency device in Las Americas SWRO

From PELTON turbine To ERI system

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Operating Modes in the installation

One stage or Two stages

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2 operating modes

The plant can be operated with 2 modes:

� Working with one stage� Working with two stages

A B C

One Stage Close Open Close

Two Stages Open Close Open

Operating ModeValves

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Why is important a good regulating system?

� Potential problems

� How to avoid this potential problems

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Potential problems

If the regulation of the process is not correct, some problems could appear:

� Cavitation in the ERI booster pump. When the plant starts it has to be assured that there are not air in the circuit.

� Water Hammer problems in membranes. It´s important to regulate the start of the high pressure pump to avoid this important problem which could damage the membranes.

� Sudden stop of the ERI pump. The regulation system must be capable of stop the high pressure pump and all the process to avoid important problems in membranes.

� High flowrate of brine. The regulation of the system must allow stop the process when the brine flowrate is high to avoid problems in the ERI devices.

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Potential problems

If the regulation of the process is not correct, some problems could appear:

� Cavitation in the ERI devices. It´s necessary a pressure transmitter in the low pressure side of the ERI pipe to control that the pressure is not lower than minimum to avoid this problem

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How to avoid this Potential problems?

During the design of the plant special attention must be focus in the following issues:

� Instrumentation� Flow transmitters� Pressure transmitters

� Regulating valves

� Control loops

� Correct sequence of the control loops� Start-up of the process� Shut-down of the process.

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Basis of the regulation

� Alarms and Control System

� Control Loops

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Alarms and Control System

The control system includes alarms which warn about wrong operation:

� Low flowrate in the lowpressure inlet of the ERI

� Low flow rate in the impulsionof the ERI booster pump

� High leakage of ERIs

� High conversion of the system

High pressure side

Low pressure side

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Alarms and Control System

The control system includes alarms which warn about wrong operation:

� Low conversion of the system

� Problems with the protectionof motors and bearings of thepumps

High pressure side

Low pressure side

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Regulation – Control Loops (1/2)

3 types of control loops:

FIT

Pipe B

Flow Indicator Transmiter

Pipe A

Regulating valve

Set Point

Set Point

Pipe A

PIT

Pipe B

Regulating valve

Pressure Indicator Transmiter

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Regulation – Control Loops (2/2)

3 types of control loops:

Set PointFIT

Pipe B

Flow Indicator Transmiter

Pipe A

Pump with frequency converter

F/I

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Regulation of the RO –Mode 1

Reverse Osmosis system working

with One stage

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Before Star-up –Mode1

Operate manual valves:

� Close valves A and C

� Open valve B

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Schematic P&ID – Mode 1

1st STAGEPermeate

2nd STAGE

High Pressure

pump

Brine

Booster pump

Booster pump

Reject

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Step 1 – Pressurization of the circuit (Mode 1)

1st STAGEPermeate

2nd STAGE

High Pressure

pump

Brine

Booster pump

Booster pump

Reject

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Step 2 – Control Loop 1(Mode 1)

1st STAGEPermeate

2nd STAGE

High Pressure

pump

Brine

Booster pump

Booster pump

Reject

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1st STAGEPermeate

2nd STAGE

High Pressure

pump

Brine

Booster pump

Booster pump

Reject

Step 3 – Control Loop 2(Mode1)

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Step 4 –Control Loop 3(Mode 1)

1st STAGEPermeate

2nd STAGE

High Pressure

pump

Brine

Booster pump

Booster pump

Reject

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Important remarks

• Keep minimum pressure in the inlet of the pumps

• Adjust the opening percentage of the regulating valves

• Keep the minimum pressure in the ERI system. Due to the headlosses

• Keep minimum pressure in the ERI Booster outlet. To avoidoperation problems.

• Define perfectly the star-up ramp of the HPP. The increase ofpressure in the inlet of the membranes has to be progressive to avoid damages

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Regulation of the RO –Mode 2

Reverse Osmosis system working

with Two stages

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Schematic P&ID – Mode 2

1st STAGEPermeate

2nd STAGE

High Pressure

pump

Brine

Booster pump

Booster pump

Reject

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1st STAGEPermeate

2nd STAGE

High Pressure

pump

Brine

Booster pump

Booster pump

Reject

Step 1 – Pressurization of the circuit (Mode 2)

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1st STAGEPermeate

2nd STAGE

High Pressure

pump

Brine

Booster pump

Booster pump

Reject

Step 2 – Control Loop 1 (Mode 2)

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1st STAGEPermeate

2nd STAGE

High Pressure

pump

Brine

Booster pump

Booster pump

Reject

Step 6 – Control of PITs

Control of the Differential Pressure

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CONCLUSIONS

Regulation of double stage SWRO plant after improving the energy consumption using ERI technology.

Case study: Las Americas SWRO plant, Canary Islands

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CONCLUSIONS

� The improvement of the Energy Efficiency is not only a questionof changing electro-mechanical equipment (Energy recoverydevices, HPPs and booster pumps). Each plant must be studiedspecifically, and a dedicated regulation system is fundamentalin order to avoid problems during the life of the facility.

� Depending on the design of the RO and the operation modes ofthe plant, specific control loops must be implemented.Instrumentation, control valves and frequency converters arenecessary to design these control loops.

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CONCLUSIONS

� It´s important the design of the regulation during the normaloperation, but also the sequence of the control loops in othersituations as:

� Start-up of the RO� Shut-down of the RO� Flushing of the RO

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CONCLUSIONS

� Since September 2015 , LasAméricas SWRO plant is inoperation with the design andthe regulation system showed inthis presentation.

� The reduction of the energyconsumption is better thantarget. Depending the operationmode, it varies between 0,4and 0,5 Kwh/m 3

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ACKNOWLEGMENTS

Javier Iturriaga (Erection & Commisioning)Gerardo Cremer (Engineering)Javier Cuasante (Drawings)Manuel Fernandez (Execution)

The plant was built, erected an commissioned in 2015 by thefollowing team of SUEZ Degremont Spain :

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CaribDA 2016 Conference & Exposition“Developing and Affording New Water Sources”

31st May – 3rd June 2016 in Trinidad

Regulation of double stage SWRO plant after improving the energy consumption using ERI technology. Case study: Las

Americas SWRO plant, Canary Islands

Julen Cabero, PhDSUEZ Treatment Solutions, SAU

CaribDA 2016 Conference & Exposition · Julen Cabero, PhD SUEZ Treatment Solutions, SAU. Title:...

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