Les enjeux du dessalement de l’eau de mer

Les enjeux du dessalement de l’eau de mer

Mary-Fleur Tordjmann

Master 2 ILTS

2005 - 2006

Sommaire

• Introduction

• Présentation du domaine

• Arborescences

• Fiches terminologiques

• Texte de traduction

• Conclusion

Introduction

Why did I choose « seawater desalination: what is at stake? »

Water is vital to life.

Water covers about 75% of Earth’s surface, 94 % being salt water from the oceans and 6 % freshwater. (O.K. Buros, The ABC’s of Desalting, 2000)

The need of freshwater is increasing as the world’s population, industrialization and agriculture are growing. In 2005, the world’s population amounted to 6.5 billion people. (UN)

There is not a best desalination process. They all have advantages and drawbacks. So one of the questions is: which of the desalination processes is more appropriate?

Seawater desalination: definitions

What is desalination? A process that removes salts. Desalination can be found in nature through the water cycle.

Desalination is a term that applies to all processes which remove salts.

Seawater desalination: a brief history Seawater distillation desalination was known in

Antiquity.

The first industrialized distillation devices were found on steamboats in the 19th century. But real development dates back to the 20th century.

Research started in the 50s in the United States.

In 1952, the US government created the « Office of saline Water » while the French government created a Comity in 1966.

In the 70s, oil crises fostered investment by Middle-East countries.

400 AD (Desware Information Booklet, UNESCO)

Seawater desalination today Today industrialized desalination technologies are:

• Distillation: Multi-stage flash distillation; Multiple-effect distillation; Vapour compression distillation.

• Membrane: Reverse osmosis; Electrodialysis, only used to desalt brackish water.

Membrane vs. Distillation in the world: in 1998, reverse osmosis 42%, electrodialysis 6%, multi-stage flash distillation 44%, Multiple-Effect distillation 4% and vapour compression distillation 4%.

Reverse osmosis

(Introduction to Desalination Technologies in Australia, AFFA, 2002) (Desware Information Booklet, UNESCO)

Multi-stage flash distillation

(Desware Information Booklet, UNESCO)

Multiple-effect distillation

(The ABC’s of Desalting O. Buros, 2000)

Vapour compression distillation

(Desware Information Booklet, UNESCO)

Seawater desalination: what for?

Seawater desalination aims at converting salt water to• Freshwater for: Agriculture; Industry;

• Drinking water for human consumption.

To be used by a growing number of countries.

Energy consumption

A lot of energy is needed to run a seawater desalination plant and depends on the process.

As a result, operating a plant is still expensive.

Using a lot of power has a negative environmental impact.

The environmental impact

A high energy consumption has an undeniable environmental impact.

It seems that there is discrepancy between French and English speaking countries’ points of view about the impact of the plant itself. It seems there are more texts about the negative impact of desalination plants in English texts.

Seawater desalination alternatives

Research is being conducted to try to find alternatives to reduce technical, environmental and energy drawbacks.

Today there are many alternatives more or less developed: • Freezing desalination for cold countries;• Hybrid processes i.e. the association of two desalination processes;• Membrane distillation;• Nuclear desalination;• Renewable energy powered desalination such as wave-powered

desalination, solar desalination, wind-powered desalination, cogeneration i.e. plant that produces energy while desalting seawater, etc.

At least 27 different desalination processes.

Which process to choose?

Many studies held in the world compare all the processes to determine which of them is the most appropriate depending in the situation.

One has to take into account:• Seawater parameters such as salinity, turbidity, temperature, etc; • Energy consumption and availability;• Technical requirements like pretreatment, equipment standards or

equipment deterioration;• Environmental impacts, that are more considered in the English

speaking countries.

Seawater desalination future

Today desalination is still under intensive research and new technologies are being developed.

Examples: French scientists have developed a new distillation evaporator in 1999. The world's low temperature thermal desalination plant designed by an Indian Institute opened in July

2005 on Kavaratti island, in India.

Expert

Author of my text:

Philip Davies

School of Engineering, the University of Warwick

Aston University, Birmingham

http://www2.warwick.ac.uk/fac/sci/eng/staff/ad/publications/

http://www2.warwick.ac.uk/fac/sci/eng/staff/ad/publications/

ArborescencesLégende

hyperonyme/hyponymes

tout/parties

cause/effet

opération/résultat

chronologiques

« rapport »

« apport de »

« risque de »

« détermine »

fiches longues

ayant arborescence termes

termes

« par phénomène de »

Liens Termes

liste non exhaustive

1 : Le dessalement

dessalement

dessalement des eaux saumâtres

dessalement de l’eau de

mer (2)

dessalementdes eaux usées

Légende

liens hyperonyme/hyponymes

termes

termes

termes à fiches longues

termes ayant arborescence

2 : Le dessalement de l’eau de mer

prise d’eau

dessalement de l’eau de mer

prétraitement

dessalement (procédés de) (3)

post traitement

distribution

eau de mer (12)

eaud’alimentatio

n

eau produite

saumure

eau douce

eau potable

énergie (4)

rejet

recyclage taux deperformance

(distillation)

tauxde conversion(osmose inverse)

Légendeliens hyperonyme/hyponymesliens opération/résultat

liens chronologiquesliens « apport de » liens tout/partiesliens « rapport »

3 : Les procédés de dessalement

Légende

termes procédés utilisés pour l’eau de mer

procédé de dessalement

hybride avec changementde phase

termes procédés non conventionnelspour eau de mer

membranaire chimique

échange d’ionsélectrodialyseosmoseinverse (5)

congélationdistillation (11)

liens hyponyme/hyperonymes

membrane (9)distillation

àmultipleseffets (6)

distillationpar

détentessuccessives (7)

distillationpar

compressionde

vapeur (8)

solaire

à longstubes

verticaux

à tubeshorizontaux

arrosés

effet

liens tout/parties


thermocompressioncompressionmécaniquede vapeur

4 : Les types d’énergie pour le dessalement de l’eau de mer

type d’énergie

cogénération

thermal

électrique

renouvelable

nucléaire

distillation parcompression de vapeur (8)

distillation àmultiple effets (6)

distillation pardétentes successives

(7)

osmose inverse (5)

solaire

éolienne

des vagues

dessalement nucléaire

récupérationd’énergie

turbopompe

intégrée

systèmeà piston

turbinePelton

saumure

à cycle direct

à recirculation récupérationde chaleur

Légendeliens « apport de »

liens tout/parties

liens opération/résultat


termes énergie pour distillation et osmose inverse

5 : Le dessalement de l’eau de mer par osmose inverse

pompehaute pression

module membrane (9)

eau d’alimentation

saumure

système derécupération

d’énergie

eau douce

Légendeliens « apport de »

liens tout/parties

liens chronologiques



6 : Le dessalement de l’eau de mer par distillation à multiples effets

vapeur 1er effet 2ème effet

vapeur

n effet

saumure

évaporation

condensation

condenseurfinal

eaud’alimentation

vapeur vapeur

cellule

échangeurde chaleur

Légende

liens « apport de »

liens tout/partiesliens chronologiques


températurepression

liens« par phénomène de » liens cause/effet


eau doucefluidechauffant

saumure

7 : Le dessalement de l’eau de mer par distillation par détentes successives

réchauffeur 1er chambre 2ème chambre

vapeur

n chambre

saumure

évaporation

eau douce

condensation

eaud’alimentation

vapeurvapeurréceptable

échangeurde chaleur

température

condenseurcondenseurcondenseur

réceptable réceptable

vapeur

eau doucetempératurepression


Légende


liens tout/parties

liens cause/effetliens « par phénomène

de » liens chronologiques



8 : Le dessalement de l’eau de mer par distillation par compression de vapeur

échangeurrécupérateur de chaleur

eau d’alimentation

saumure

eau douce

évaporateur/condenseur

compression de vapeur

vapeur évaporation

eau douce

saumure

condensation

Légende



liens « par phénomène de » liens chronologiques

9 : Les principales contraintes techniques liées à la membrane d’osmose inverse

membrane

polarisation

entartrage

colmatageencrassement

salissures

tartre

précipitation

réversible irréversible

gâteau

matières en suspension matières colloïdales

hydroxydede magnésium

sulfatede calcium

carbonatede calcium

silicatesde calcium

compactage

pression

Légendeliens « par phénomène de »

liens cause/effet

liens tout/parties liens hyponyme/hyperonymes

liens « risque de »

Fouling index

liens « détermine »

biofouling

eau de mer (12)

érosion corrosion

10 : Autres contraintes techniques liées au procédé d’osmose inverse

installation

Légende


liens cause/effet

normes


11: Les contraintes techniques liées au procédé de distillation

installation

encrassement entartrage

corrosion

érosion

Légende



12 : Propriétés de l’eau de mer

propriétés del’eau de mer

turbidité

matières en suspension

selsdissous salinité température



Légende


Tree diagramsLegend

hyperonym/hyponyms

whole/parts

cause/effect

operation/result

chronological

« ratio »

« adding of »

« risk of »

« determine »

long records

with tree diagramterms

terms

« by a phenomon of »

Relations Terms

non exhaustive list

1: Desalination

desalination

brackish waterdesalination

seawater

desalination (2)

waste waterdesalination

Legend

hyperonym/hyponyms relations

terms

terms

terms with long records

terms with tree diagam

2: Seawater desalination

water intake

seawater desalination

pretreatment

desalination (processs of) (3)

post-treatment

distribution

seawater (12)

feedwater

product water

brine

freshwater

drinking water

power (4)

discharge

recycling performanceratio

(distillation)

efficiency

Legend

hyperonym/hyponyms relationsoperation/result relationsChronological relations

« adding of » relationswhole/parts relations« rapport » relations

entrainment impingement

cause/effect relations

plume

3: Desalination processes

Légende

terms processes use for seawater

desalination process

hybrid based on physical change

terms non conventional processes for seawater

using membrane chemical

ion exchangeelectrodialysisreverseosmosis (5)

freezingdesalination

distillation (11)

hyponym/hyperonyms relations

membrane (9)multiple-

effectdistillation (6)

multi-stageflash

distillation (7)

vapourcompressiondistillation (8)

solar

withvertical tubes

with fallingbrine film

with horizontalTubes with falling film

effect

whole/parts relations

non exhaustive list

thermal vapour

compression

mechanicalvapour

compression

4: The types of power used for seawater desalination

type of power

cogeneration

thermal

electrical

renewableenergy

nuclear

vapour compressiondistillation (8)

multiple-effectdistillation (6)

multi-stage flashdistillation (7)

reverse osmosis (5)

solarenergy

windenergy

waveenergy

nucleardesalination

energyrecovery

integrated turbopump

pistonspump

Peltonturbine

brine

heat recovery

Legend« adding of » relations


operation/result relations


terms power for distillation and reverse osmosis

solardesalination

wind-powereddesalination

wave-powereddesalination

5: Reverse osmosis

high pressurepump

membrane assembly membrane (9)

feedwater

brine

energy recovery device

freshwater

Legend« adding of » relations


Chronological relations



6: Multiple-effect distillation

vapour 1st effect 2nd effect

vapour

nth effect

brine

evaporation

condensation

final condenser

feedwater

vapour vapour

vessel

heatexchanger

Legend

« adding of » relations

whole/parts relations chronological relationsoperation/result relations

temperaturepression

« by a phenomenon of » relations cause/effect relations

temperaturepression

freshwaterfluid

brine

7: Multi-stage flash distillation

brine heater 1st stage 2nd stage

vapour

nth stage

brine

evaporation

freshwater

condensation

feedwater

vapourvapourrecipient

heat exchanger

temperature

condensercondensercondenser

recipient recipient

vapour

freshwatertemperaturepression

temperaturepression

Légende




« by a phenomenon of » relations

chronological relations



8: Vapour compression distillation

heat exchanger heat recovery

feedwater

brine

freshwater

evaporator/condenser

Vapourcompression

vapour evaporation

freshwater

brine

condensation

Legend



« by a phenomenon of » relationsChronological relations

9: The main technical disadvantages of reverse osmosis membranes

membranescaling

fouling

scale

precipitation

biofilm

suspendedsolids

colloidalparticles

magnesiumhydroxide

calciumsulfate

calciumcarbonate

calciumsilicates

Legend

« by phenomon of » relations


whole/parts relationshyponym/hyperonyms relations« risk of » relations

biofouling

film

biological matters

non exhaustive list

« determine » relations

Fouling Index

seawater (12)

erosion corrosion

10: Other technical disadvantages related to reverse osmosis process

device

Legend

« risk of » relations


standards


11: Technical disadvantages related to distillation processes

device

scaling

corrosion

erosion

Legend

« risque de » relations


12: Seawater properties

seawaterproperties

turbidity

suspended solids

dissolvedsalts salinity temperature



Legend

non exhaustive list

Terminology problems

Difficult to select the terms.

Still not sure about the terms and their equivalents because the same word can be written in many ways. For example: Multi-Stage Flash distillation without upper case, freshwater in two words, desalination synonymous like desalinization, desalting (which is an old word), dessalement or désalinisation in French, acronyms for desalination processes such as reverse osmosis: RO, a shorter version of the terms like vapour compression distillation and vapour compression, etc.

Brine and concentrate vs. samure and concentrat.

Terms in British or American English?

The difference between French and English texts will oblige me to deal with terms without equivalent.

Literature searching problems

A lot of documents on the subject in English, from articles to reports, organizations, associations… and as a result it is difficult to select them.

The most interesting documents in French are books which take a

long time to deal with.

Wave-powered Desalination: Resource Assessment and Review of Technology

Wave-powered Desalination: Resource Assessment and Review of Technology

Text presentation

I found this text on the Internet. The text was actually published in

“Desalination” in the December 2005 issue.

A text which is renewable-energy-oriented because energy consumption is one of the major problems in seawater desalination. As a result, a lot of terms in the text do not directly belong to the subject area of my dictionary.

Desalination in the dictionary because it is crucial to understand

what it is about to comprehend the text.

Text sample

Wave-powered desalination: resource assessment and review of technology

Le dessalement• couplé à/associé à/généré par• l’énergie houlomotrice/l’énergie des vagues/l’énergie due aux vagues :

évaluation de la ressource et bilan de la technologie

Text sample

The second technology reviewed is based on the Salter duck. The duck was originally conceived at the time of the UK Wave Energy Program of the 1970’s and demonstrated that it was possible to achieve an efficiency of wave-energy extraction exceeding 80% using a single degree of- freedom mechanism [25,33].

La deuxième technologie traitée utilise le canard de Salter. L’invention de ce canard remonte à l’époque du Wave Energy Program britannique (un programme gouvernemental qui, en plein choc pétrolier, visait à utiliser l’énergie houlomotrice comme alternative) lancé dans les années 70. Ce nouveau système avait alors démontré qu’il était possible de récupérer 80% de l’énergie générée par les vagues en utilisant un mécanisme à un degré de liberté [25,33].

Text sample

The UK government did not pursue this or other wave technologies at that time. However, Salter later proposed a version of the duck for desalination, in which vapour compression equipment is actually housed inside the floating duck [34,35].

Mais, le gouvernement britannique cessa toutes recherches sur l’énergie houlomotrice. Cependant, plus tard, Stephen Salter proposa une version du canard conçue pour le dessalement dans lequel une installation de compression de vapeur est logé à l’intérieur même du canard flottant à la surface [34,35].

Text sample

Rocking motion will give rise to changes in water level inside the hull of the duck, generating pressures sufficient to drive evaporation and condensation across a falling-film heat exchanger. The process is designed to run at 100ºC, but the large size of ocean-going ducks (typically 6–12 m in diameter) will minimize heat losses.

Le hochement provoquera un changement du niveau de l'eau à l'intérieur de la coque du canard, générant assez de pressions pour que l’évaporation et la condensation se produisent en traversant l’échangeur de chaleur à film tombant. Ce procédé est conçu pour fonctionner à 100°C, mais la grande taille de ces canards de haute mer (en général 6-12 m de diamètre) permet de réduire les pertes de chaleur.

Conclusion

Many uncertainties remain.

Many details will probably be changed.

Documents

Les enjeux du dessalement de l’eau de mer