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Desalination, 73 (1989) M-190. Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands. 181. EVALUATION OF SOLAR POWERED ...

Desalination, 73 (1989) M-190 Elsevier Science Publishers B.V., Amsterdam -

EVALUATION

OF SOLAR POWERED

I.S. Al-Mutaz

and M.I.

181 Printed in The Netherlands

DESALINATION

PROCESSES

Al-Ahmed

Chemical Engineering Department, Riyadh 11421, Saudi Arabia.

King Saud University,

P.O.Box

800,

ABSTRACT Besides processes solar

the conventional have

been

energy.

freezing,

possible

These

.. . etc. to provide

appropriate

solar

comparison.

nation

processes

reference

desalination

include solar

fresh water

desalination

process,

of the active

desalination

in remote

process

be carried.

The Arabian

utilization

the

best

The selection of the ever

region

will

the fossil

to justify

of

osmosis,

considered

of the possible

with

desalination

reverse

problem

Gulf

Comparison

plants will also be presented

solar desalination

is

aird areas.

is a unique

study.

other

electrodialysis,

In this paper, the evaluation will

for the evaluation

selected

distillation

by the application

processes Undoubtely,

alternative

cesses

thermal

done

by pro-

solar desalibe used

as a

fuel powered

the recommendation

of the

process.

INTRODUCTION Most type

of

or

Quite

the

reverse

desalination osmosis,

few processes

economical

studies

in desalination design

showed

plants

of equipment

The

cost.

powered

about

in Gwadar,

either

processes

Solar

energy

benefit

plants

are

Pakistan

operated

fossil

MSF, fuel.

intensive

is the controlling

parameter

is free of cost and need only clever

desalination

Table

1

lists

some

countries.

plant

(3900 gpd).

on an area

by

flash,

Meanwhile

from this energy.

in various

14.8 m3/day

of multistage

use solar energy.

that the cost of energy

to get most

earliest solar It produced

installed

These

are

with small capacities

of the solar pond desalination

Chile.

processes

RO.

was

established

in 1872

in

The largest

solar

still was

of 9100 m2 producing

about

27 m3/day

(7120 gpd). The utilization An Italian Scientist,

of solar energy

in desalting

Della Porta, mentioned

OOll-9164/89/$03.50 0 Elsevier Science Publishers B.V.

saline water

is an old issue.

the use of solar energy

of desali-

182

Table

1

Solar Still Desalination Country

Location

Plants

Date Built

Basin Size

Production rate, L/day

m2 Australia

Cape Verde Chile Greece

India Mexico Pakistan Spain Tunisia USA

USSR West

Indies

Inslands

Muresk I Muresk II Muresk III Muresk Mk IV Coober Pedy Coober Pedy Mk VI Caiguna Caiguna Mk VII Hamelin Pool Griffith Griffith Mk VI Griffith Mk VII Townsville Darwin Mk VI Mt. Derrimut Mk VI Sania Maris do Sal Las Salinas Quillagua Symi Symi II Aegina Aegina II Salamis Paimos Kimolos Nisyros Fiskardo Kionion Megisti Bhavnagar Natividad Island Gwadar I Gwadar II Las Marinas Chakmou Mahdia Daytona Beach, Florida Original Deep Basin Second Deep Basin Large Inflated Plastic Church World Service Bakharden, Turkmenia Bulhara region, Uzbek Petit St. Vincent Haiti

1963 1966 1971 1973 1966 1972 1966 1972 1966 1967 1970 1972 1971 1972 1972 1965 1872 1968 1964 1968 1965 1968 1965 1967 1967 1969 1971 1971 1973 1965 1969 1969 1972 1966 1967 1968

5;; 410 230 140 230 90 45 740 4460 100 2690 2595 1490 1465 390 8644 2510 2045 2200 2400 2520 380 95 305 9060 870 440 1300

833 833 524 406 6350 1021 776 85 1211 908 524 319 529 204 102 1660 14262 401 2570 7300 4329 4250 1098 26116 7570 6056 6513 7098 7450 1100 280 880 21818 2574 1270 4164

1959 1961 1959 1963 1969 1975 1967 1969

230 250 220 150 600 505 1710 223

530 563 640 430 1628 1460 4900 640

370 370 230 180 3160 455 370

183

nation from

in the early 17th century(l). largest

1970's

simple

served

powered

as

a catalyst

Basically,

system

for

our natural water

in the world.

enhancing

research

The

and

supply comes

energy

crises

development

in

of solar

processes.

The amount ddq

desalination

on

strike

the

the

receive

of solar energy

high

radiation

distance

and

receiver. solar

The

incidene Arabian

radiation

received

in

received

the

long

Arabian

equal to an annual rate of 30x1015 reserves

59.2%

of

the

total

Gulf countries.

surprisingly feasible

that

radiation

countries time

Gulf

world

The amount

negligible.

from location

in

had

are among the year.

countries

to another to

travel

till

those

places

that

The

is 5200

depen-

average

Kcal/m2.

daily

This

is

KWh, more than six times the whole world oil

(MWh = 0.086 ton of oil = 0.112

About Arabian

angle Gulf

for

varies

barrel of oil).

desalting of water

Solar desalination

capacities

produced

are

in the

by solar desalination

has been proved

for rural areas of small communities

located

industrial

is

to be economically

purposes

and millitary

use(2). The plants

following with

are

discussions

an evaluation

of the possible

and rating

based

solar

powered

on the Arabian

desalination

Gulf countries

con-

ditions. SOLAR DESALINATION

PLANTS

Solar energy can be converted tion

or to heat

at high

can be used directly

in desalination

can be also converted tricity

Solar energy

so called

directly

active

processes, energy

solar energy

to obtain

below

after

so called

passive

or photovoltaic

absorp-

This

heat

methods.

by the use of heat engines. devices

It

Elec-

to be used

utilization. It uses the solar The vapors

up to its evaporation. the product.

its boiling

by direct

focusing.

form of solar desalination.

to heat saline water

and collected

at a temperature

by absorption

by thermoelectric

still is the simplist

are condensed porates

to electrical

can be generated

in desalting,

to heat at low temperatures

temperatures

points.

Water

formed

in these stills eva-

Normally

evaporation

occurs

184

at 50-600C

(122-14OoF).

(0.08-0.10

gal/ft2).

Oifferent These

designs

cover,

water

the

tried

using

evaporation,

ME,

Low or high temperature

plate

the operating

low heat capacity,

and good

and

to improve

rate is 3.3-4.1

efficiencies.

low air content,

insulation

around

multieffect

thin

vapor

the basin(L). film

liter/m2

diffusion

tight

Increasing stills

will

the still performance.

forms.

focused

basin

radiation

Multistage

Flat

to achieve

tight

also improve

ferent

still production

solar stills were designed

incident

energy.

The average

This

steam

collectors

collectors

and

MSF

can

be

operated

steam is generated

is used

usually

to provide

operate

can produce

steam

at

indirectly

by

by solar collectors

heat

of dif-

for the distillation

a temperature

below

in the temperature

solar

unit. While

1OOoF.

range of 150 to 4550C

(300-8000~). Alternatively, compression, plate

collectors,

derive

solar

a heat engine

Photovoltaic into

electricity. could

operate

be

ponds,

Most

used

of

for

of energy

time.

solar energy

can process

other

electric

Vapor

turbine. heated

Flat

fluid

to

processes

They

systems often

space

technology.

electricity

two important These

storage

to

efficiencies conversion

were

used.

problems

faced

are the low efficiency So most desalina-

of energy.

and work during certain

hours in the day

are illustrated efficiency

in Table 3.

of 9-15%(3).

do not differ much from the conventional

consist

power generator,

the

produce

of solar desalination

However,

in desalination.

conversion

in to

light from radiation

use in the ED stacks.

plants.

in capacity

desalination

systems.

were

applications

cells often has an energy

Solar powered

collectors,

application

and the inefficient

are limited

Typical

to d rive a turbine.

can be run by this

collectors

or directly

of these

tion processes

desalination

their

of solar energy

conversion

Photovoltnic

focused

desalination

the solar stills,

2 shows examples

the application

can be used plants

for RO plant.

pumps for RO plants

Besides

steam

cells had been used since 1955 to convert

They

Table

the produced

VC, or RO desalination

of

feed

a distillation

water

pretreatment,

or membrane

solar

unit with an

U-stage RO MSF

Kuwait Sulaibiya

IO-stage

SPRO

MED

La-Paz, Baja Cal., Mixico Conception de1 Ore, Mexico Arabian

ZO-effect 55-effect SPRO

Al-Ain U.A.Emirate Cadarache, =rance

Gulf

la-effect

Unnn-Al-Nar Abu-Dhabi

Takami Japan 16-effect

Two-stage RO in// with 24 effect dist.

Yanbu, Red Sea, Saudi Arabia

Island

One-stage 40 in series with ED

Yanbu, Red Sea, Saudi Arabia

Kuwait

Indirect

Yanbu, Red Sea, Saudi Arabia

MES

MSF

..

YSF

ME8

MES

MSF

freezing

in

RO two-stage series

XC

Brownsville, Texas, U S A

stage

Desalination technology

Single

location

Ranking , Texas, USA

Plant

Table

60

500

600

6.000

4.000

10

120

16

20 25

100

Bracdish

Sea water

Exhaust steam

Brackish

Sea vater

Sea water

Sea water

Brackish

Sea water

Sea water

Sea water

_-

3.478

Sea water

Sea 'water

__ 210

3ra;