Sea Water Desalination in Kuwait — A Report on 33 Years Experience

Sea Water Desalination in Kuwait — A Report on 33 Years Experience

Desalination,63(1987)1-55 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands Sea Water Desalination in Kuwait Experience A Re...

3MB Sizes 10 Downloads 158 Views

Desalination,63(1987)1-55 Elsevier Science Publishers B.V., Amsterdam -

Printed in The Netherlands

Sea Water Desalination in Kuwait Experience

A Report on 33 Years

A.A.J. AL-ZUBAIDI Development Centre, Ministry 71651 Shamiya (Kuwait)

Water Resources 12020, Shamiya,

of Electricity

& Water,

P.O. Box

ABSTRACT Kuwait has been fully dependent for its fresh water supplies on sea water Multi-Staqe Flash Distillation Distillation Plants for the last 33 Years. Plants (#SF) have been successfully used in Kuwait for about 30 years, during commissioning, which period Kuwait has gained wide experience in the design, operation and maintenance of MSF Distillation Plants. This paper attempts to cover this long and unparalleled experience. Survey of all existing Power & Distillation Stations is presented and the reasons The behind the development of the Dual-Purpose Plants are explained. Main design historical development of MSF Distillation is also charted. features which characterize Kuwait's Plants are outlined. A summary of the experience gathered over the years concerning Plants Operation & Maintenance investigations and research into the viability of other is given. Finally, desalination methods are summarized.

I

INTRODUCTION Kuwait is located

covers

most

weather

of the

Arabian

conditions,

has very limited In the past, collection

of

in an arid area which is an extension

The collected 1925

to

Kuwait

electrical

new

era

relatively supply.

of

of

fresh

Kuwait

development,

The accelerated

demand

high

needed

of small,

OOll-9X4/87/$03.50

rates

of

for

the

medium

special

upon the types

past

on

of

during the

boats

called

small

income was established and

As

diesel

industrialization

development

needing power

was due to the big rise in

the huge increase

immigration

to start

as well as electrical

into the of

and heavy industries

power and fresh water

primitive

Later on,

by

the

in both utilities

of the

introduction

in

modernization

of living of the population,

of electrical

some

less than 1 MW.

of fresh water supplies

as a result

was

water

of oil in Kuwait, enough

huge quantities

which

water supplies

into

relied

totaling

the standard

force

water

some 100 miles away from Kuwait city.

in Iraq,

supply,

by severe

of rivers and lakes and

of fresh water.

rain

imported

sets of limited capacity

With the discovery a

is characterised

water was used in the dry season.

1950

"Dhows" from Shatt-Al-Arab its

area

relied for their fresh

quantities

period

for

resources

the Kuwaities small

This

of rain water and absence

under-ground

wells.

generating

peninsula.

scarcity

of the desert which

supplies.

0 1987 Elsevier Science Publishers B.V.

the

in the population

country country,

requiring

of

a labour and

the

large quantities

2 modernization

In order to affect this development, Kuwait

realised

electrical Ministry

of

securing

the basic

power

need for securing

and fresh

Electricity

adequate

such vital supplies

(M.E.&W.)

in order

and reliable

The state

water supplies.

& Water

and industrialization,

to

of Kuwait

assume

to meet

the

the ever

sources of

entrusted

the

responsibility

of

increasing

demands

of

these vital necessities. For steam

electrical power

power

stations

Kuwait

generation,

utilizing

the

relied

available

fuel

on conventional which

includes

crude oil, and gas oil. As for the huge fresh water supplies, the

sea

for

obtaining

production

of fresh

which

common

are

respective From

to

utilities

the

economical

savings

"Dual-Purpose

stages

of

power

raw

power

water

generation

and

Kuwait

realised

of combining Plants", in

generation

and

both and

the

early

plants

the

factors

and

their

to a great extent. the

(Power

been the

1950's

oil,

for

are many

production

appreciated

utilities

it has

needed

There

water

heavy

Kuwait turned to

supplies

processes.

are linked and inter-related

development

electrical

necessary

by distillation

both

beginning

termed

the

water

thermal

to

& Water)

practice

design

and distillation

advantages in what

since

and

production

and is

the early

construct plants

both

side by

side on the same site. This

paper

desalination

II

will

review

the

in Kuwait and accumulated

SURVEY OF POWER GENERATION At

present,

generation are fully

there

are

established

A seventh

water.

while

sea

water

STATIONS

stations

of distilled

of

over the last 33 years.

PRODUCTION

dual-purpose

and operational(l),

Power Generation

first

station(2,31.

dual-purpose

in

Kuwait

for

the

Five of these stations

the sixth

station

station is still in the planning

water production units called

& Water Production plant

built

The power generation

the non-condensing,

back-pressure

plant,

is in the

stage. These

MIGPD

(454.6 m3/dayl, plant

due to

giving

a total

its limited

Kuwait

was

in

1953

in 1953,

very low performance

consisted

type each with

output of 1.0 MIGPD

capacity,

has

been out

units are concerned, ratio

at

Shuwaikh

of three steam turbines

type each having a capacity

also installed

As far as the distillation

of relatively

in

Station.

plant consisted

'A' raft of the submerged-tube

power years.

experience

developments

are:

1) Shuwaikh The

and

& DISTILLATION six

of power and production

stage of construction. stations

emergence

(2.5 - 3.11,

of

of 0.75 MU. The

of 10 distillation a capacity

of 0.1

(4546 ml/day). of service

The

for many

these were inefficient, and had relatively

very

3 high operational and replaced flash

subsequently having

type,

performance

and maintenance

a

During

the period

still in operation. MIGPD

of

4.0

the first

plant

MIGPD

demolished

(18184

in 1967

m3/day)

having

at Shuwaikh 'A' station

of the extraction/condensing

type were

The extension units

These

type.

extension

extension

to the distillation

called

'8'

units were

1968 by two distillation

each

type,

were

called

distillation

submerged-tube in

capacity

1954/1955,

Power generation

4x7.5 MW steam turbines

later

in 1970 by unit product

units

'New A' which was of the multi-stage and

a

ratio of 8.

completed.

0.1

These

costs.

a capacity

also demolished

units

(Bl & 821

of 2.0 MIGPD

added

were

of the

of

the

and replaced

multi-stage and

of

of ten

also

in 1967

(9092 m'/day)

was

and are

plant consisted

which

raft,

station consisting

flash

a performance

ratio of 8. During

the

years

1957/1958

station was completed This

plant

was

an extension

to the

power

by adding 4x10 MW steam turbines

demolished

few

years

An extension

ago.

out during the same period.

'C & D' raft, consisted

of four units, each with a capacity

of the then new multi-stage

ratio of 3.5.

These distillation

type to be built on commercial after that date,

of much

bigger

the world's

out of service

of 6.0 MIGPD

added,

first units

new distillation

units

(2273

a performance of their

until 1976 and

and kept as emergency

(27276 m'/day)

'6'

type.

called

of 0.5 MIGPD

having

basis. These units were utilized

in 1982 with-three

capacities

The plants

(MSFl design,

units were

they were taken

by. They were replaced

flash

called

to the distillation

plants was also carried

m'/dayl,

plants

of the condensing

stand-

(Dl, D2 & D3)

and higher performance

ratio of 8.

In 1961 'C' Power units consisting were coannissioned. A year earlier capacity

of 1.0 MIGPD

multi-stage

These

(Gl & 621,

in 1965, commissioned units

five

commissioned

in 1977.

in 1968.

gas

turbines

the total present

station

(El & E2) each with a

These two units were of the units

apart from the units mentioned

each with a product capacity each with

of 1 MIGPD a capacity

so

(Fl & F2) of 2 MIGPD

All these units, as well as, all subsequent

(MSF) with a performance

Therefore,

units

steam turbines

ratio of 5.6. The distillation

and another two units

conznissioned in Kuwait

concerned,

Shuwaikh

added.

units were added,

were two units

distillation flash type

were

MW condensing

any longer.

Four more distillation

comnissioned

3x30

two distillation

(4546 m3/dayl

flash type with a performance

are not in existence

far.

of

since

then

are

of the

multi-stage

ratio of 8. As far as the power plants are

each

having

installed

a

capacity

of

power and distillation

are 324 MW and 32 MIGPD respectively.

40.5

MW

were

capacities

of

4

2) Shuaiba This

North Power Generation

station

consists

each with

type,

of five

an installed

cotmaissioned over the period capacity

another

three

in

(22730 m'/day) Therefore,

1965-1969.

units and

1968,

five

power

units were

gas turbines,

each with

a

finally

each

with

an installed

plants

MIGPD. The distillation Therefore,

installed

capacity

of,

three

during

1965-

a capacity

of

2 MIGPD

a capacity

of

5 MIGPD

(D) with

power and distillation

capacities

of

of

Station.

of the extraction/ These

134 MW.

condensing

power

units

were

a capacity

of 5

1970-1974. of six

units,

units were commissioned

the total installed

each with

over the period

power and distillation

1971-1975.

capacities

of Shuaiba

are 804 MW and 30 MIGPD respectively.

This station with a capacity

consists

& Water Production

Station.

of seven extraction/condensing

steam

of 150 MW. These power units were commissioned

Six more gas turbines,

each with a capacity

turbines,

each

over the period

of 18 MW were added and

in 1981.

The distillation MIGPD

plants which consist

(27276

m3/day), unit

were

distillation

capacity

of 1.0 MIGPD was commissioned

be used to evaluate of anti-scalent Therefore, East station

the performance

additives the

(A81,

of seven units,

commissioned

Another

which

is

installed

an

over

period

of utilizing

1978-1979.

unit

This experimental

and reliability

power

each with a capacity the

acid-treatment

in 1985.

for the prevention

total

with

a

unit is to acid instead

of scale.

and distillation

capacities

of Doha

are 1158 MW and 43 MIGPD respectively.

5) Doha West Power Generation This station

consists

1983-1984.

& Water Production

of eight steam turbines

type, each with a capacity the period

unit

with

& Water Production

consist

4) Doha East Power Generation

commissioned

each

of six steam turbines

over the period

South station

& C2) one

they consist

of lMIGP0 commissioned

are 400 MW and 14 MIGPD respectively.

consists

The distillation

6.0

Two more

are concerned,

Cl

South Power Generation

commissioned

of

The

in 1971.

the total present

This station

1977-1979.

plants

(B,

commissioned

North station

3) Shuaiba

type,

of the extraction/condensing

of 70 MW.

A2 & A3) each with a capacity

commissioned

Shuaiba

Station.

of 25 MW were added in 1969.

(Al,

1966,

steam turbines

capacity

As far as the distillation units

& Water Production

Station. of the extraction/condensing

of 300 MW. These power units were commissioned

over

5 The distillation

plants were

installed

of four units each with a capacity 1983-1984.

Stage

II consisted

7.2 MIGPD, commissioned

of twelve

over the period

the total

Therefore,

over

two stages.

of 6.0 MIGPD,

installed

units

Stage I consisted

commissioned each with

over the period

a capacity

of 6.0 -

capacities

are 2400

1984-1985.

power and distillation

MW and 96 MIGPD respectively.

6) Al-Zour This consist

four

with

a total

be constructed

each with a capacity

capacity

side', type,

it will each with

The power plants of 111 MW.

These

over two

stages.

Stage

I will

of 6.0-7.2 MIGPD. The first unit

in 1987.

the total installed

Eventually,

power

condensing

by the end of 1986.

plants will

of eight units,

should be commissioned

On the

of the extraction/

gas turbines

units should be completed The distillation

Station.

stage.

The first unit is under comnissioning.

of 300 MW.

also include

consist

& Water Production

is in the construction

of eight steam turbines

a capacity will

Power Generation

station

power and distillation

capacities

will

be

2511 MW and 96 MIGPD respectively.

7) Sabiya Power Generation

& Water Production

This new station which beyond

is designed

1990's, is still in the preliminary

stages. Work done so far consists

power

respectively.

and

distillation

the power

and preparatory

of consultative

it is estimated

In conclusion, installed

Station.

to satisfy

and water planning

By 1990, it is envisaged

and design

services.

that by the end -of 1986, capacities

demands

will

be

5372

the total actual MW

that the two capacities

and

208 MIGPD

will be 7084 MW

and 246 MIGPD respectively(l).

III

DEVELOPMENT

OF DUAL-PURPOSE

PLANTS

1) Introduction The combination

of both

production

in what

economical

solutions.

that

is termed

some of the partly

expanded

concerned,

as a completely

it is definitely

steam

generation

plants,

significant

and

distillate

offers very

feature

of this

in the steam turbines

for producing

flash distillation

not be considered

power

dual-purpose

A special

as the heat input necessary the multi-stage

electrical

plant.

distillate Although

wasted energy

water

water

attractive

and

combination

is

can be utilized

from

the extracted

sea water

in

steam should

as far as the power

plant

is

a very cheap source of energy for the distillation

6 plant compared

to the cost of energy

is not part of a dual-purpose the unused

steam actually

Dual-purpose reliability, satisfy

plants simple

the daily

required

enhances

the efficiency

should be suitably

operation

varying

plant which

the utilization

of some of

of the power cycle.

designed

to satisfy controllability,

They

and economy.

and seasonal

by a distillation

Furthermore,

system.

consumers

should

also

be designed

requirements

for

to

power

and

supply

and

continuously

and

fresh water. There

is

distillate

a

fundamental

difference

between

electrical

supply.

The electrical

power

demand varies

water

as the electrical

energy cannot be stored,

it has been generated. instant

it

is

in

demand

consumption

varies

also varies

seasonally

The distilled amounts and

Therefore,

of brackish

carried

connected

to and integrated are designed

and water

the

plants

in distilled

is that

and they

day

Different

multi-stage different

while

flash

be

distilled constant

are minimum,

Another

important

type

(MSFI.

types. These are:

on drinking

storage

many

the

system is

fluctuations reserve

water production

for

water

to

reservoirs.

days.

in

need Thus,

although

they could vary

feature

of distillation

at their full

limitations

rated capacity

in design

load in case of power generating

or/and

to

units could

on the demand.

Plants

of the dual-purpose

water production

It

suitable

distributed

and to act as strategic

could

Of Dual-Purpose

arrangements

with

The water distribution

due to possible

depending

Arrangements

the distilled

being

need to be run continuously

be varied continuously

2) Possible

and

water production

scale formation,

day to day.

is blended

and underground

the required

seasonally.

or as near to it as possible minimize

This

and from

plants

before

system.

production

not

monthly

consumption.

to take up the daily and short-term

Therefore,

variations

the day

out

with elevated

case of emergencies.

weekly,

the

once

at the

in order to satisfy WHO standards

by the water distribution

throughout

to

consumed

be generated

the year.

consumers

vary

power must

equal

from the distillation

water

in both water demand

be

throughout

throughout

treatments

These reservoirs

it should be directly

electrical

shall

continuously

water

appropriate

and

power

plants are possible.

plant is concerned, The power

plant

it is nearly

generating

units

As far as

always of the could

be of

a) Gas Turbines these

In

relatively

Power Plants the

plants,

exhaust

high temperature

heat energy

and water

reduction

in

the

with reduction operation

electrical

in distillate

and to secure

boilers

may

be

distillation more electric

of

plants

including

while

electricity

the

in relation

heating

steam steam

to

pressure turbine

in

electrical in the

suitable

and thus

do not have to use a specific to burn

kinds of steam turbines; Condensing

back-pressure

generation

is expanded

for heating

is then

as

turbines

for

generate

fuel for the

any kind of fuel

condensing,

are mainly

in the

as

providing

back-pressure,

used for electricity

and extraction/condensing well

heat

turbines

heating

steam

are used for

water

are therefore

circulating

brine.

heater Steam

These turbines

turbines

ensure

the

ratio

constant

mainly

distillation

plants.

turbines

relatively

are

with power

these

Furthermore, too

small

turbines

generation

This

it condenses

exhaust

giving

its

back

for

with no condensers

and

is pumped

the

be

be met

ratio

of

distillate

water

it suffers from the fact that this upon

the

electric

to meet

cannot

will

and temperature

plants.

condensate

highest

However,

depends

The

type.

to the power generated. and

where

are designed

production is

electricity.

low pressure

in the distillation

into the brine

of the non-condensing

Back-pressure

live steam of high pressure to generate

is at relatively

purposes

introduced

to the

steam turbines,

in the steam turbine

reuse in the boiler cycle.

electrical

coupled

gas oil, heavy oil, or crude oil.

steam from the turbine

and suitable

operation

automatically

as any

To ensure better flexibility

outputs

be possible

In the case of back-pressure

latent

be

plant

is lost

production.

and temperature

steam

will

a back-pressure

normally

and extraction/condensing.

exhaust

on the distillation

could be used. The live steam produced

It should

There are three main

distillate

at

power generation

in operation

generation

distillate

electrical

mainly

water production.

to

through

steam.

steam boilers

generation,

are

Power Plants

Steam turbines generation

which

power.

b) Steam Turbines

for

and depends

power

higher

expanded

plants

turbine

steam is then used as the heat input

that flexibility

fired waste heat boilers

power,

gas

the ratio between

is fixed, This means

ratio.

the

plant.

gas turbines,

production

performance

from

The produced

in these gases.

for the water distillation When utilizing

gases

are passed into a waste heat boiler to recover the

high

ensured with

steam

power

generated

demand. and

reduction

demand

The

any

for by

the these

flexibility

reduction

in the

in

of the

distillation

plant output. adequate

Such plants are suited for cases where

production

electrical distillate considered

of

distilled

with

design,

the

In

water

production,

whereas

requirements ratio

coupled

this

generation.

Extraction/condensing

The

water

power

as a secondary

the

Live

steam

steam

turbines

power

power

stage

from

the

permit

generation

generation

boiler

in the turbine

in the turbine,

pressure

and

pass-out.

pass-out

steam

for to

generated. heat

to

the

condensate

cooling

which

is almost

exhaust

be disposed

are important

ensure non-reliance

3) Main Advantages The advantages

Saving

in

Operational

lower than the single-purpose

plants.

expanded

in

mainly

be

relatively

brine

heater

low

extracted

as

giving

is pumped

its

back for

steam which is not

lower

stages

additional

to waste. feed

is

At a certain

is

the

thus

The

the

can

be

its latent

exhaust

steam

The energy

cheap value

for any significant

the latent heat which

of

power

giving

cycle.

is of relatively

energy

can

temperature,

plants

in the condenser

plants

production.

power.

Steam condensate

in the boiler

of low thermal

and

of the low energy

pressure,

to individual

of

as it

electrical

in any case need to

both electrical

power generation

and flexibility

in the design

water to

of one system on the other.

And Limitations

Of Dual-Purpose

of dual-purpose

the

and distillate

should be considered

Capital

Plants

plants are:

Investment

of

the

Boiler

Installation

and

Fuel

Costs.

The combined

advantage

is

of by condensation.

In this arrangement, production

generation

production

steam of

in the

is discharged

used in the distillation

and posseses

pressure

of heating

steam is condensed

the steam

a)

is

exhaust

water

steam

the

of both utilities.

distillation

brine.

is pumped back for reuse

power generation

load

is

water

water

of electric

is condensed

plants

condenser

This exhaust

for

The remainder

distillation the

at high

quantity

suitable

latent heat to the recirculating

required

power

and distillate

generation

specific

reuse in the boiler cycle.

turbines

base

product

ample adaptation

and distillate

being

for the

temperature

This

constant

main

electrical

varied within wide ranges to satisfy the requirements

expanded

a

to ensure

product.

of electrical between

it is important

boiler installation sumnation electrical

of saving This

dual-purpose

saving

of individual generation

in the boiler in

capacity

boiler

plant selected.

in case of dual-purpose

boiler

capacities

and water production installation

combined

costs

capacity

in case plants.

plants is of separate

This has the

in case of dual-purpose

depends

upon

the

type

of

9 Another boiler

advantage

as

capacity purpose

in

the

of combining

case

of

is relatively plants.

higher

This results

size which contribute

distillation

plants.

capital

cost

investment

purpose

plants.

has

electrical

cooling water

in case

the

advantage

generation

culverts

are relatively

dual-purpose

plants

intakes for single-purpose

cost.

Plants cheap

performance

Culverts as well

as compared

with

as distillation

the necessary

installations,

sea water

the

single

of

Sea water intake

therefore

building

plants

quantities

intake and discharge

to

for the

reducing

Installations

water production.

costly

value in

ratio

plants in comparison

plants

common

for single-

of considerably

near the sea for securing

saving in building

of

in low optimum

and feed water for distillate

and discharge considerable

boilers

boiler due to the increased

of the Distillation

Intake & Discharge

power

need to be constructed

boiler

combined

saving in fuel operating

for the distillation

cl Saving in the Sea Water

in one

the

wasted heat energy of relatively

results

This

installations

that

any of the individual

Cost Investment

plants

is

in higher efficiency

of partly

case of dual-purpose

Steam

than

for both

plants

to a considerable

b) Saving in the Capital The availability

steam boilers

dual-purpose

separate

there is culverts

individual

plants.

d) Waste Heat Energy The utilization production

of part of the waste

of distilled

the cost of the above unit cost. Therefore water

el Reduction

unused waste

in the Operational

overhead

which costs.

distillate

lower

& Maintenance

boiler

l.esult in

less

water unit production

maintenance

cost.

power plants unit cost

to the distillation

in dual-purpose

and Overheads

sea water and

of reducing

in the

by loading production

production

plants

in case of single-purpose

of

than the plants.

Costs.

of sharing various

installation,

This has the advantage

power

costs for the combined

productions

plants enjoy the benefits

such as administration, culverts,

heat energy

are considerably

costs for separate

Dual-purpose

heat energy from

lower the electric

the total production

and electricity

corresponding

water,

common

intake

operational

facilities

and discharge

costs

both electrical

and

less

energy and

10 f) Utilization

of Services

The installations production

on the same site

of both electrical

are inter-connected

power

and thus

generation

and

rely on each other

distilled

water

for some of their

services. Distilled steam

water

boilers

and

of high

purity

in the

power

plants,

this make-up

site.

This

eleminates

As

saving

in

for

distillation

auxiliaries power

power

brine,

on

the

same

costs and minimum

g) Improvement

sea

site

the

power

water

which

Cycle Thermal

water from the distillation

station boiler cycle at relatively improving

combined

dual-purpose plants on the

pumping

and

costs,

unit as required

in case

is needed

and

for

distillate

driving

This from

plants

is readily

available

result

in

in

saving

the

pumps.

electrical

losses.

of the Combined

Condensate

of

in the

power generation.

in the case of dual-purpose

plant

transmission

as

and

of small make-up

electrical

plants,

such

purposes

from distillation

transportation

plant of electrical

feed

In case

cycle.

available

the need for installation

electrical the

in

for make-up

generation

feed is readily

results

of single-purpose

plant

is needed

cycle

Efficiency

plants

is returned

high temperature.

thermal

back to the power

This has the advantage

efficiency

in

case

of

of

dual-purpose

plants.

dual-purpose

Although, limitations. demand ratio

The electrical

is less variable of

drop

in electrical

design aspects electrical

load,

reliability

additional Kuwait,

mostly load

between

and

and

while

allowing

capacity,

of

both

investment

Many

Such of

of the dual-purpose

and back-pressure

of electrical

power generation

any reduction

a reduction

in the

these

utilization

of waste

water

heat energy.

The

periods

Therefore,

far

special

in order to enable reducing plants

design

design

plants

steam turbines

in electrical

distillate

water

to

operate

at

at the same time the flexibility

special

to distillate

whereas

seasonally.

low demands

aspects

are

involve

is the limited flexibility

in

power and water demands.

are characterized

power generation production.

will

in

production.

Generally,

aspects

adapted

design to satisfy the proper balance between

Gas turbines

fact that

only

distillation

and ensuring

systems.

later.

limitation

the

also have some

nature,

varies

high

they

ratio of drop in water demands.

costs.

economic

is of varying

steady

and will be discussed

Another

advantages,

should be taken into consideration

their full production and

have many

load demand

and

exceeds the corresponding

the

plants

They

by low ratio

They suffer from the will be accompanied also

ensure

the electricity

the

by

best

that would

be

generated

by the steam

flow to the evaporator

normal amount of electricity generating

generated

is considerably

by the turbine.

lower than the

Therefore,

units will have to be added or extraction/condensing

other power

steam turbines

will have to be used. Extraction/condensing electric

power

the demands

before

of distillate

being

expelled

is less efficient.

the

design higher

and

in

condensing

steam turbines.

conditions

in one

must

lead

capital

The final limitation any problems

reflect

thermal

some more electric of the

the overall

in the

steam power plants.

heat

energy

utilization

of steam for the distillation use

of

specially

investment

on the

dependent

In The Operation

experience

part

in a condenser,

to overcome

that one system is not totally

Kuwait

to

cost

be considered

4) Kuwait Experience

Once

than

designed in

the

any difficulties

turbines standard

special

design

and also to ensure

on the other.

Of Dual-Purpose

operation

of

the two systems,

Therefore,

other.

plants may

steam

case

stems from the fact that by combining

might

of

to satisfy

In the case of higher capacity power generating

of big quantities

resulting

of the ratio

in order

water and the rest produces

of energy

complicate

the variation production

by condensation.

in the boiler must be wasted

extraction

water

only part of the waste heat is utilized

generated

units,

enables

to distilled

of both. In these turbines

in the production power

steam turbines

generation

of

Gas turbines

Plants

dual-purpose

plants

in Kuwait are mainly

is

limited

to

used for peaking

and system emergencies The high in Kuwait plants

and low demand

fall

more

demand

periods

for both electrical

At

high

units will be operating period,

simultaneously

such

remain reasonably

units that

of the

both

demand

water

will

available

(MIGPD)

plants

of the power units, The design

be

all

taken

capacities

and fresh

water

This makes dual-purpose electrical

power

and

high load factor while at for

annual

relative

to

overhauling the

demands

constant.

is

extraction/condensing dual-purpose

period

at a relatively

The ratio of the annual peak demands, fresh

power

at the same time of the year.

attractive.

distillation low

almost

25.

turbines utilize

and

in 1985 of electrical

This as

high

a

ratio

result

is coupled

of

power

best

Kuwait's

Depending

(MW) and

be met

with

existing

on the capacity

with one or two distillation

to the unit principle

special factors

could

most

this type of turbines.

each unit

is according

There are certain

about

units.

system.

which are taken into consideration

design to ensure

high flexibility

and reliability

power generation

and distillation

production

in the operation

systems

in the

of both the

so that no system will be

l? fully dependent

on the other in order to meet satisfactorily

under

different

fresh

water.

investment

conditions,

These

Normally

rating

units (MCR).

are

(Pressure

variable

decreases

not

dependent

with reduced

MCR full

for

of

regulating

distillation

and

capital

more

than

Load of Steam Turbine 80%

stable continuous

The condition

rating.

the

of

point

The

load.

their

maximum

load of steam turbines of the extraction

of the steam turbine

extraction

and to obtain adequate

steam

heating

the

flexibility

to give at all steam turbine steam

Pressure

output.

power

additional

pressure

load on the steam turbine.

are designed

quantity

distillate

loaded

at Partial

at the extraction

upon

To ensure the best economy steam turbines

Output

continuous

and Temperature)

and

for electrical involve

as follows:

The minimum

is about 30% of the maximum

demand

considerations

of Full Rated Distillate power

continuous

is

population

design

and they may be summarized

a) Production

steam

the

special

at all times and

steam

required

controllers pressure

for the production

are provided the

to

in operation,

loads down to 27% of

on the

suitable

of the rated

extraction

value

as

line

per

the

plants requirements.

b) Direct Steam Supply from the Boiler During

low electrical

the steam quantity distillation of

the

boiler

unit requirements.

distillation by expanding

desuperheaters are

appropriate

from

the

boiler

distillation

without

Therefore,

utilizing steam

required

through steam

is normally

sized

steam

the

obtained

necessary

conditions plant

to

power

load is low,

point will be lower than the

the design must allow the operation

live

for distillation

Operation:

Electrical

of non-availability

possible any

condensers

this

when the turbine

period,

at the extraction

ensure

directly

pressure

(Pressure

operation.

This

adequate

steam

and

from

the

reducers

and

Temperature)

stand-by supply

supply for

the

operation,

it

units.

c) Single-Purpose

shall be

plant

to the

that

In case

demand

and pressure

to

generate

extraction

steam

must be designed

Power Generation

of the distillation the for

maximum

plant

continuous

distillation

to be able to condense

for

rating

plants.

of the

turbine

Therefore,

all the steam flow.

the

13 d) Single-PurposeOperation: Distillate Production In case of non-availabilityof the steam turbines, it shall be possible to run the boiler separately for distillate water production only.

Boilers are

designed for minimum stable load of operation in order to satisfy the steam requirements for full rated capacity of the distillation plant. e) Operation of Distillate Plants from other Power Units The whole power generation and distillation production system are designed according to the unit principle operation. However, in order to provide the highest degree of flexibility and independence in operation for both systems, an inter-connecting comnon header system is provided for low pressure steam supply to the distillation plants.

With this provision any power unit can

supply any distillation plant as and when needed.

Future expected electrical power demands as well as fresh water demands are estimated based on the expected increase in population future consumption patterns, and anticipated industrial expansion in the future.

Such expected

future yearly demands are projected for a period of ten years and over. These estimates are constantly revised and updated. Based on

these estimates,

future power generation and distillation

production stations are planned and designed bearing in mind the following facts: i. Ratio of electrical power and water demands. ii.Five years period is normally allowed from the initial planning till the units are in operation. iii.The construction period of power units normally takes about 36 to 42 months, whereas in the case of distillation plants, this period is normally 24 months.

IV

HISTORICAL DEVELOPENT OF NSF IN KUWAIT Before a historical review of the developments of multi-stage flash (MSF)

distillation plants in Kuwait is given, it is useful to state the principle of MSF distillation. A simplified block diagram of a typical MSF Evaporator is attached. A liquid at a given pressure has its own saturation temperature. This temperature decreases as the pressure drops. Therefore, a liquid under such saturated condition contains maximum amount of heat energy and will boil or vaporize if either additional heat is supplied or pressure is reduced.

TO RESERVOIR

SECrlON

STEAM

HEAT INPUT

HEATING

TO EVAPORATOR

SIMPLIFIED

HEAT

BLOCK

RECOVERY

DIAGRAM

SECTION

OF A TYPICAL

M.S.F:

q-

PARTITIffl

SEA

SEA

EVAPORATOR

7

PUMP

GAS

L- ANlI-FOAM

NCN-CONMNSABLE

@I

WATER

PRODUCT VAPOUR

m

m m

STEAM CONDENSATE

m

SEA WATER BRINE

&l

OISCHARGE

a

LEGEND

FLATE

INTAKE

TUB

WATER

WATER

EXCHANGE

DISTILLATE

HEAT

15 When

a

liquid

chamber

in which

boiling

point

inmediately

at

saturation

the vapour

of the

"MSF"

distillation water

of

stages are operated driving

sea

each

section,

Recirculating

brine

is finally

is still

hot enough

added

brine

in

condenser

tubes.

so that a proper a portion

The flashed caused

the

flash

being

carried

the demister,

stage condensers distillate

tray.

where

stage flows

into

almost

constitute

recovery

section, The

steam

in

it flows into the occurs. As

lower pressure,

it

a series of inter-connected

into the heat recovery

brine to maintain

a material

is complete

and

constant

section is

balance

it goes

sea water is circulating

of heat that was

added

The cooling

is salt free,

process

by

the heat

stage condenser.

orifice,

a

all

section.

by the heating

to maintain

section,

results

Therefore, intercept

in droplets

any

such

inside the

it condenses

After

and

tube

first

stage

to

prevent

the

bundle

and drops

The distillate last

them

from

passes through

cool tube

surfaces

the

turbulence

contaminating

the vapour releases

to

heater

at the upper part of

the vapour

with relatively

in the tubes.

the

the violent

of brine

droplets

on the

of heat

in the brine

sea water apart from

is arranged

tray.

in the

on being

back to the sea.

however,

a demister

into contact

from

or

are maintained

heat

is returned

In the process of condensing,

in cascade

collected.

through

is maintained.

heat to the brine or sea water

finally

reducing

cycle

out into the distillate it comes

temperature

feed water is discharged

produced

to

of

at each

produce

sea water is used to reject or discharge

heat balance

chamber

stages

side

vapour

it

vapour.

to

is divided All

the heat recovery

as blow-down

in order

to the amount

vapour.

evaporator

fact

These pressures

last stage

recirculating

by the flashing

upward moving

this

sea water feed from the heat rejection

The cooling

vapour

that the

temperature,

and initial flash evaporation

is discharged

used as a make-up

a level

the final stage.

In the heat rejection

is equivalent

unheated

"flash evaporation",

to boil again at a slightly

quantity

The brine

an

this flashed

pressures.

tube

while passing

level. Make-up

sufficient

repeated.

the

a pressure

from the

but a portion

evaporator.

which

process

of

last three

to its terminal

until it reaches

The unflashed

concentration

into

of the evaporator

repeats the flashing

section,

the

by flashed

then through

first stage chamber

flash chambers,

flows heated

heated

the brine heater,

the brine

lower

while the rest constitute

where it is gradually brine

advantage

successively

Usually,

is called

The MSF

feed.

at such

by condensing

under vacuum condition.

the ejectors.

rejection

water

at

full

into

its incoming

This phenomenon

take

introduced

is below

is then obtained

plants

from

stages

is

is maintained

liquid

boils or vaporizes.

distilled number

pressure

resident

and high purity distillate

temperature

into the its latent

produced

stage

of the

where

in each it is

16 The following historical review covers all MSF units that have been installed in Kuwait during the last 30 years.

Some of the early plants had

already been dismantled, however, relatively more attention is given to these plants,

as *their design manifested the

real

development of

the

MSF

distillation process. Only design aspects which are unique to each plant is discussed. The review given should be coupled with the information given in Tables 1,2,3 and 4

regarding plants general characteristics and design

parameters for the heat input, each plant.

heat recovery and heat rejection sections of

Plants that appear in the tables are those that are still in

operation, and plants of identical design are grouped together. Shuwaikh 'C' & 'D' From 1953 until 1957, submerged-tube type.

all sea water desalination plants were of the

Due to the rapid development of Kuwait and the urgent

need for more potable water, distillation capacity.

it was decided to enlarge the sea water

In January 1956,

the Government of Kuwait issued

specificationsfor two distillation units to be added to the Shuwaikh plants. These two units with a production capacity of 0.5 MIGPD each, primarily of the submerged-tube type,

were to be

and optionally of the newly developed

flash-type(4). The expectation was to receive offers only for submerged-tube evaporators due to Kuwait's own previous experience in operating such a plant, as well as the limited work done on flash-type evaporators in commercial production throughout the world at that time. Westinghouse Co. offered 4-stage flash-type evaporators and,

after various considerations,it was decided to accept their

offer subject to modifications and tests on a proto-type plant at their factory before final approval of the design could be granted. After

extensive

discussions between

M.E.&W.'s Design

Engineers and

Westinghouse Chief Designer, the company was asked to introduce a number of modifications into their design.

The recommended alterations covered many

mechanical design features regarding materials, pumps,

etc.

But the most

important ones were those which affected the performance of the plant - for example,

an external loop seal for interstage flash brine control.

The

original design arrangement to prevent vapour lock was not accepted, as it would have led to an increase in brine levels in the stages, thus resulting in carry-over of dissolved solids into the distillate.

It was suggested that

Westinghouse use short inter-connecting pipes between stages with an orifice in the bottom of the pipes.

This they accepted. Dissatisfaction was also

expressed regarding the dimensions of the bottom stage,

as with the high

vacuum present, carry-over was expected. The Kuwaiti side was worried about

17

2;

3

j;or;o "

1506.77 I I 13.89

IMild Steel

I

I

I IMild Steel I

IR.N.B. I I IK

155.56

YNi

170/30

16.71

1'230.00

I

I

11.22

1'g.05(i"1

I

I

I3080 I

I

j I I

,*

(Mild Steel

I

16

IR.N.B.

I I

I /

**

IMild Steel

I7

I

1R.il.B.

155.56

j:O$ "

115.57

13251.50 I

I'.22

I

I

I I

/l.gB

IMild Steel

vpcrrt(on at 1loY urrng special polymer additives

tubes n/se<.

11.98

I

IMtId Steel

I

1n:l.jSteel

I Velocity through 12.13

Shell material

I

I

12.00

(Mild Steel

I

12.50

[Mild Steel

ID

I

1R.N.B.

175.00

j:O!$ " 1

117.80

lB

I

I

IR.N.6.

175.00

12% FC* 21 11

1'7.32 166Eu. 3011

I I 14000.00 13544.00I

I

Il.g6

[Wd

Steel

I I

12.01

111.66

14Bg.5

I

11.09

FN*I.

I

i75.00

I I I

I

I

[Carbon Isteel 12.12-1.1.

i5t4inw icarbon ;;;W; 316L ISteel lgO/lO cu-Ni Ir~Sin Icladding

IR.N.B.

I

i75.00

11.90

7

R.N.B.

~.~

I

llB.75

f3544

II.22

I

I

I

I44.0(1.73',

1'37B

I

Yest I Phase II I I’ I

iDohr

66xCu. 3OzI66K", 32w1170/30 Ni. 2SFe !2: Fe. ZYlnlCu-Ni

16.15

3653

1.22

I

j532

I’

I

I Aa I I

1B.oOW~~25.4W

1904

I

Phase

12.0 I

;",,d Steel ICarbon 5tce

Iepoxy resin

I I' I I lEpoxy resin [Epoxy restnlphenol

I I IMild Steel IMlld Steel ICarbon 5tee I I I I / I#

15 I

/R.R.B. I

174.93

Iz';p

19.5g

13120.58 I

I

;25.40(1.0", /44.45(11*~ jlB.,OW I I II.22 Il.22 11.22 I

1,929

I

I’

I

01,02.03

~31.75W I

I 11430

I

II

I

1

jShuwalkh'O'! )ohr Nest iDoh. East

14078 I

I’

I

jOoha East 1 Al - A7

12019

I

I’

I

160.33 I

j::!:p

17.01

12452.5s

1'.22 I

I

11g.o5w,

f5340

I

ii

-

ICarbon Steel; * I * I I I IEpoxy resin (Epoxy resin lEpoxy resin Hater box inter- IEpoxy resin Ifleoprew nal protection I

Yaterbox mater.

I I

I

InrId Steel

Tube Wpport p1ete material

I 1

j6

II I

plate

No. of tubes support plates

Tube

material

IR.N.B I

I 175.38

ICu-Ni

1g.27 170130

11341.48 I i

lRO,led INrvsl Brass

Tube pl@te 122.23 thickness (111111!

lube material

Tube length lml

Tube surfscc arca (!?I

/,.22(0.046"&.22

Tube thlck"Css IfWl)

I

125.41l.O"l I

Outride tube drtlneterlmll

/ I

I

I 12072

il

I I 120 23(1") I .

I

I

il

No. of tuber per pass

I ,838

I

i2

No. of tube

pas*es

/ I

jShw,aikh'B' iShuwaikh'A' jSh"aiba Southj Shuaibs IAl.A2,A3,A4 I South IShueiba tI.'O'I AS b A6

;Shur,ba 'A' /Shuaiba '8' /Shualba 'C'

Plant Location b Identification

iShu,,r$kh'F'iShwikh%

TABLE 2 - HEAT INPUT SECTIONS

19

jl.l.6.

support

pl'tCs

tube

1

lM,ld Steel

I

I 111114Steel

Il.?? I

j$.” jl22

I1;::y /1.22

Le.

1.



j;.;;;;;

IO”:%

JRild Steel I I

I

lllildSteel

I

rdd(tl*es.

I

IprInt Il.96

IRubber

!

\Xild Steel

I I

iMild Steel

IS

11.63 I

j::F!z

IMild Steel

I

1Mld Steel I

/C

I

IA.".&

I I

/R.".B.

I I I6 I

/:I;?: I

jEi!Y

p!;: ”

\!Wd Steel

I

11.9,

I IRubber IpaInt

t

iM(ildSteel

I !8

I

i3

jR.I.6.

jR.I.6.

I4

I

1$-z t

I

porr

Il.64 - 1.85 11.96 - 1.9911.96 I I

IRUbbW Ipaint

I

Lo I

Icoating

resin. IEpoxy

11.35

I I EPOXY /coating

5. \Csrbo" 5.

l,,,ldSteel ICarbon Ste&bo" I I

!

I

5.

Ico'L'ng 12.13-1.95.

lww

I

Lo"

;C.rbon 5. tkoatcdl

!

19

I

/R.1Lfl.

I

LB.

26Rl I65.00 112.56') 165.00 112.56‘)

IMild Steel

i

j?

16;.00 iIZ.SS'l

I65.00 l(2.56')

j6

I9444 I

116.45

i3

306l66%u,3oM11666*u,3ow j26Pc. 2lm IZYC.

/R,ld Steel ;C,rbon Stctl;CM,o" 5. icarbon 5. IIcoatr4) Ikoated) I

!

le

jA.l.6.

. :;il:

166XU. 3ozJl+ I66scu. lzz Fe. 2"wl y$Fe*

I:“!E Y

f

I

13.92 I646 I

117.70 Im1.00

110674.5

I

i3

:1,.44

i3

110193.aa I

11.22 I

131.75 l(l.25")

j2076

117.71

jlz2

131.75 l(l.25'1

11992

i3

;",ld Steel I

j6

IR.II.6. I

1R.".6.

I

I36 10 I(+,

1 IZ%

17235.33

115.50

11.22

I

131.75 l(l.25')

jl56(1

i3

I36 10 ICI;-\

l:Z:

I 1:“‘: u-

I

139.66 l(1.57')

1:6!:

/6967.50 I

15746.19

13713.14

13297.02 I

11.22

I

133.02 1(1.3"1

i3 1137o

i 116.32

j1.22

1 $$j

11440

i3

i 113.41

I

i 19.6’3 19.73

jl75O

1,912

Qprratloo at llO*C using special polywr

I

IYcIotIty throqh ItL*es m/ICC.

hater box

I inter- IRubber Inal prottct*on ynt

IYptor boy lutcrirl

I

(plate mterial

ihbt

I'"""'

Lo. of

I2

j:$': '

I Ilube plate Ithtcknerr (ml

/WC plate lMtCri.1

16.x)

! Ilube length InJ

I(O.048’J

/h& th~ckOtSLil.22

i3

13

21 scale formation temperature Hagevap

was

93.3"C

on the outside

where a maximum

brine

in order to operate maintained should

inside

be made

purity

of

baffles

area to condense

especially the

in the fourth

heat

precipitate

(180-190°F)

offered

local boiling

is permissible

(80

was

flash

the distillate.

Also,

was

doubted

The

scale.

doubted

There

chambers.

must be

and that a provision

to get rid of

to cascade the vapour before

specified

evaporators,

the tubes ppm)

was

to scale

that conditions

due

were

to

the

two vertical

it reached

the heat

the vapour velocity

was high

stage which is under a higher vacuum.

transfer

especially

The coefficient

if

scale

should

inside the tubes.

Westinghouse their

inside

in the

chamber

top brine

suggested

of submerged-type

it was requested

so as to avoid

as

treatment

of about 82-88°C

trouble.

disitllate

of the

chemical

of the tubes

temperature

the tubes

the

since the recommended

with scale until then was confined

surface

without

plates in each flash transfer

and

for acid cleaning

the

arrangement

of

(200°F)

Kuwait experience

(PD8).

formation

especially

inside the tubes,

design

agreed

and to

to introduce

build

size in cross section, a) Brine control

most

a proto-type

of the recommended for two

stages,

alterations

which

would

into

be full

and to study the following:

between

stages.

b) Purity of distillate. c) Scale formation The pilot orifices entry

tests.

plant

of

tests

11.43 cm

of the

top

for the brine

(4.5 in)

flash

orifice

operation

unsatisfactory

size to

and 175-245

ppm is obtained

respectively,

resulting

justified

concern

the

as originally

Tests were carried

showed

purity point

the baffles

velocity

stages

from the first,

over

at the of

the exact

that

the original

of view.

plates.

the

second, distillate

dimensions

design

was

This was mainly due

The dimensions purity

third

were then

of 30,

40, 60

and fourth stages

of 85 ppm. This clearly

of the

fourth

stage

flash

designed. out with reduced

equal to that for full load. The first

that

balance

However,

loads and at a top brine temperature

(nearly 3°C higher than design) with a brine velocity

100 hours.

and

keep the

load,

so that distillate

in average product shown

indicated

on site.

from the distillate

altered to reduce the vapour

96.11"C

the flash

optimum

pilot plant

to the small vapour path between

chamber

between

at full load and reduced

of the

stages

is the

size was to be determined

Initial

between

diameter

chamber

brine levels in all stages

control

was with

Two series

of tests

were carried

4 ppm and the second

with

of

inside the tubes out,

each for

2.3 ppm of Hagevap

22 The conclusion

compound. scalent

additive

was decided The

was that

internal

surfaces

paint.

of the

Inspection

light

and acid cleaning

of

all

constructed top

of

proto-type

revealed

the

final

the

very

of steel,

pumps

were

top,

were

as an anti-

This

sludge it

were

was

coats

accepted

the

and

cylindrical

the

stainless

In the

plant

was

stages heater

and distillate

of all heat exchangers

of

the plant

two-flow

baffles,

with

had blistered

Also,

of four rectangular

venting nozzles,

all made

painted

studied on the proto-type.

partitions,

and the tubes

while the brine nozzles,

recirculating

chambers

that the finishing

Each unit consisted

On

formation.

flash

design

The shell and all internal

were made Cu.Ni,

other.

suitable

coats were not affected.

procedures

accordingly.

each

placed.

above,

was

using acid.

in many parts but that the primary start-up

compound

but that it would not stop sludge

could be cleaned

epoxy-type

Hagevap

were made

on was

trays

of 70/30

and also sea water and brine steel.

All pumps

were motor

adjustments,

the plant

driven. When the first performed high

unit was commissioned

very well,

(150 ppm

and

except

occasionally

figure of 80 ppm). that

the

bottom

corrected

path

flash

the

was

small

steel

to

over

chamber

for

of the distillate

1500

its

demisters

was fixed

ppm against

and

a design

side as it suspected

duty.

However,

this

(absent from original

in the bottom stage the

condenser

was

tubes.

was

design)

in the vapour flow This

dropped

the

to less than 80 ppm.

revealed

originating

the operation

Shuwaikh

which

flash

The unit operation

installed

stage

of the distillate

with debris

increased

a stainless

thickness

between

salinity

normal salinity

This was not a shock to the Kuwaiti

by using

of adequate

after

that the average

the clogging

from the sea.

and performance

of the

of some of the brine heater tubes

To solve this problems unit,

a strainer

with

which affected fine

holes

was

on the sea water feed make-up.

El & E2

In 1958, evaporators

there was

still little

of

output.

specifications

large

for the required

the art is carried a

out.

Therefore,

invited

to

which

previous

work done by these companies

for tendering

for the required

from

were

16 firms

received

it

on multi-stage was

decided

plant before a thorough

Companies

questionnaire

data available

having covered

plant.

with full

experience all

The response details.

not

to

(MSF) issue

survey of the state of with

design

in this field,

flash

such plants, aspects,

were

including

in order to be considered was excellent

Eight

and replies

firms showed

that they

23 either their

manufactured design

submitting

on

flash a

evaporators

The specifications

in detail,

production

considered

or

proved

eligible

maintenance,

variations

physical

and allowable

The best commercial

for

MSF plant,

instrumentation,

design consisted

heat rejection

stages(5).

heating

some

temperature

to be

brine control, to

insure

easy

for steam and brine. and J.

Weir for a 1.0 MIGPD was signed. The

23 for heat gain and 3 for heat rejection.

The new feature in

equipment

by G.

of 19 stages only,

streams

specifications

precautions

were made before the contract

offer was for 26 stages,

The final

of

offer was submitted

but many alterations

The quantities

in sizes of flash stages,

position

maximum

specifications.

as were most of the material

such as pumps and their drivers,

scrubbing,

separate

were

were more or less design

taken in design regarding

original

conercial

hence

specifications(41.

of steam and sea water were given,

vapour

for

and

proto-type,

the

heat

with 16 heat gain stages and 3

in this design was the presence

gain

section;

one

for

of 2

recirculating

brine, the other for sea water feed. The sea water feed from the outlet of the heat gain

section

exit mixed

with

was

The designer

outlet.

then

feature

aggressive corrosion

was

nature

redesigned

sea

by the

little or no trouble

weirs

of tests on a proto-type (Professor

changed

of weirs

was agreed

and

on

(heater)

from the points

as

experience

with

exemplified

section

water

by

boxes.

the

the

very

severe

Since we had

brine in the water boxes, the plant was brine

brine

in the heat gain

control

were

section.

questioned

out in the presence

Also,

and a serious

of the design author

originally

suggested

the height surface

of the flash

in the heater was

due to our insistence

based

experience.

Apart from the introduction water feed make-up, brine

automatically

upon after changing

plates. The heat exchange

to double the surface

temperature, the

troubles.

of demisters

and the fine

and since flash evaporators

low

device from the brine operating

heater section

advantageous

previous

Kuwait

recirculating

and adding baffle

on previous

in top

in

were carried

input

Silver).

The type chambers

water

of

heat rejection

for interstage

deaerating

in the flash chambers.

because

with concentrated

to have only

the control

this arrangement

and corrosion

rejected

of

suffered

to a separate

brine from the heat

considered

of view of heat transfer This

admitted

the recirculating

an electronic

pressure outlet

steam

controller

feed

temperature

strainer

on the sea

are very sensitive

to the

was

main

fitted

heater

from the heater.

This

to changes to

by

control

a sensing

avoided

many

24 Shuwaikh

'F' and Shuaiba

North

These plants were supplied were installed North

during

production

in Shuwaikh 1965-1966

'A' Plants by Weir Westgarth

and three

as part

1 MIGPD

plants were

of a complete

The distillate

station.

Ltd, U.K. - two 1 MIGPD plants

new

produced

power

from

installed

at Shuaiba

generation

and water

the plant

had a guaranteed

purity of not more than 30 ppm TDS, and the performance

ratio was 8. Each unit

consisted

and

of

30 stages:

27 stages

The heat input section,

gain.

pass flow type and situated The material

made

of

first

recovery

which was cylindrical

near ground

and second stages of the heat gain section,

This

aluminum-brass.

while

was

deposition

the

first

plant

and corrosion

and the first

few

in

Kuwait

stages

damage of

gathered

heat recovery

confined

section.

heater,

section tubes had also suffered from sea water corrosion.

control heat

feature

in this

room at each site.

rejection

This suits

section

plant

is complete

Also, a constant

was

maintained

Kuwait as the peak water

i.e. there is no need to increase feed temperature tubes

ensured

of the heat rejection

passing the required

ensuring

and electricity

during

from

winter.

a central

feed to the operation.

occur

in summer,

The constant

flow

to Heat

stable

demands

in winter.

of low sea water

section

quantity

control

sea water temperature

all year,

production

avoidance

remote

aluminum

up till then

were mainly

rejection

new

and heat

where

the brine

The

heat

the rest of the tubes were

due to the fact that experience

brass tubes were used, scale

for

'E' plant, except that the tubes of

section were made of 70/30 Cu Ni,

had shown that

3 stages

in shape, was of double-

level.

was almost the same as for

the brine heater, rejection

for heat

velocity

sea water inside the

This was affected

from the outlet of the heat rejection

by by-

section to

the suction of the sea water pump. The sea water feed to the last flash chamber was controlled the chamber,

while brine blow-down

brine in the recirculation blow-down

control

pump discharge.

operated

in the last stage.

stages

of

efficiency The tests

contractor's the

of these

works

full-sized

of each stage, were very

useful

on

Later this was changed in conjunction

of the

so that the

with the

brine

section was controlled

plant

plants were

approved,

a proto-type

on which

can

distillate

be

Also,

represented

purity,

and resulted

brine mass flow per unit width, height of the stages.

by the level in

by the concentration

level by the

from it.

Before the final design in the

automatically

The steam to the heat input

outlet brine temperature

out

was controlled

in

adjustment number

in

tests

were carried

3 to

4 successive

order

and inter-stages changes

study

the

in stage widths to reduce

of the interstage

of stages

to

brine control.

was changed

orifice from

size, and

33 stages

as

25 stipulated

in the original

out to determine

flow inside the heat transfer

Shuwaikh

'G' & Shuaiba

These plants installed

in

commissioned

during

a performance three

section

arranged

(1

as

a special

by Westinghouse

one

ratio

similar

very

in

the

of

8.

Each

gearbox

similar

case

to the 19 mm

of

North.

plants 30 ppm

of 22 heat

pass cylindrical

'F' and

'A' plants.

plants. borehole

to

change

the

were

were

sea

from

design

capable

of producing

brine

plants,

necessitating

Many troubles

had been

and because

water to design

point of view.

an

instrumental

panel

in

the

central

One main difference

feed to the plant was controlled

by the

pump discharge.

by I.H.I.

Ltd.

Japan.

Two 2 MIGPD plants were

on the site of the submerged-tube

similar plants were also installed 1968,

and

25.4

'C'

These plants were supplied at Shuwaikh

water

as in previous

of drive.

of the brine in the brine recirculating

North

against

design of power transmission

although

controlled

The type

of horizontal

direction

from this

the plants,

'B' & Shuaiba

installed

recovery

heat input

The tubes in the

diameter

room which were very similar to the A & F plants.

Shuwaikh

during

The

unit consisted

previous

however was that the sea water make-up conductivity

plants were

of not more than

(0.75 in) outside

level, were suspect from the reliability

control

purity

were of the vertical

over the years

plants

Two 2.0 MIGPD

at Shuaiba

stages and a single

speed steam turbines

of these problems,

The

Ltd.

plant

had a guaranteed

had however

pumps

but the variable

experienced

uniform

in three tiers on top of each other.

section

in)

and

heat rejection

were

recirculating

were carried

'B'

1967-1968

stages,

mm

tests

tubes.

were supplied

TDS and

heat input

North

Shuwaikh

The plants

Hydraulic

design to 30 stages.

the best shape for the water boxes in order to ensure

had a performance

at Shuaiba

North.

plant raft

The plants,

ratio of 8 and a distillate

'B'.

Two

commissioned

guaranteed

purity

of not more than 30 ppm TDS. Each unit consisted stages,

and a single

of two tiers,

pass cylindrical

heat input and heat rejection and 25.4

mm

section. type. control

(1 in) outside

plants

room.

were

heat

sections were diameter

The steam turbines The

22 heat recovery

fully

stages,

3 heat rejection

input

section.

19 mm

(0.75 in) outside

The tubes

tubes

were

fitted

for the pumps

were

of the conventional

automatic

and

were

in the

controlled

heat

from

of the

diameter, recovery vertical a central

Shuwaikh

'A'

The plant was supplied guaranteed

distillate

was

of 8,

erected

submerged

tube

recovery

stages,

input section The

by I.H.I.

on the

plants

had

3 heat

site

was

stages

in

1970

plants,

as single units

although

adhering despite

the first

of

23

heat

cylindrical

heat

of

larger

to M.E.&W.

the

capacity

was

specifications.

large throughputs

and the

pumps were driven by vertical

large capacity

plant was the elimination

speed steam turbines.

isolating

and

feature

by-pass

of the

valves

at the

large

plants to date in Kuwait have had by-pass allow manual

control

plant

was

designed

room, serving

Shuaiba

North

capacity

to

'0' - Shuaiba

contract

of

remaining production

for

units

station

be

automatically

South

'Al'

valves. the control

valve

to

controlled

from

the

central

- 'A4'

by Alsthom

Ltd.,

desalination One

5.0 MIGPD.

four

control around

of

other

a total of six other plants.

These plants were supplied largest

bore

valves

All

if necessary(2).

control

the

where

consisted

and distillate

brine recirculating,

One noticeable

The

unit

and a single-pass

and

strictly

similar to the previous

variable

'A' raft,

The

and

ratio

level.

The pumps were sea water,

original

installed.

rejection

commissioned

supplied

than 30 ppm TDS and performance

of the

been

sited at ground

plant

Ltd. This plant of 4.0 MIGPD capacity

purity of no more

were

unit

was

installed

in Shuaiba

and constituted,

plants

in

installed in

South which

a

the

in

new

world,

Shuaiba

power

at that time, with

generation

lies adjacent

a

North,

unit

and the and

water

to the Shuaiba

North

Station. The performance

ratio

of the plants

ground

stages

and

level(6).

trays

distillate

stages

cylindrical

in general,

some changes

of

steel.

were all driven

were

Nos.l-14,

The pumps,

by electric

brine

blow-down

alternative

provision

discharge

pass

pipe.

taken

from

also

supplied

pump

contrary

heat

conformed

introduced.

a guaranteed

input

ducts

pump suction

two

in

3 heat

sited

at

M.E.&W.

plate

of the

all

stages,

piping were all made previously

followed,

motors. was

supplied

with

this

plant

recirculating separate

pump

units

discharge. each

with

but

there

was

via the recirculation

In the other units so far mentioned,

in

stages,

to then existing

to the practice

to allow brine to be rejected

the brine

distillate

section

The bottom

distillate

box in last stage, and distillate

of stainless

A

single

The plants, but

specifications, distillate

a

with

Each unit had 22 heat recovery

purity of not more than 30 ppm. rejectin

was 8,

the brine blow-down The

its

steam

own

ejectors

condenser

an

pump was were giving

21 complete

working

supplied

with

and stand-by

each

venting were cooled

condensers

using distilled

(1.25in) outside

diameter

to the circular and more

were

control

room.

Before

all

final

were

approval

operational

of the

sections

cascade

had 31.75mm

section

and

model

it possible

conditions(6).

The

tube plates.

designed

in the are

had 44.45

tests

representing

on

the

The

chambers. from

a central

the performance

to test

were

This is due

to provide better

flash

operated

was given,

a proto-type

made

tubes

vapour

controlled

of the design

using

which

the

by the unit.

and heat rejection

of the condenser

condensation

verified

for

The tube plates in all the heat exchangers

automatically

assembly,

steam ejector was also

ejectors

and the tubes in the heat recovery

diameter.

arrangement

efficient

plants

stages

the

while all the other plants had rectangular

circular,

units

of

water produced

The tubes in the heat input section

mm (1.75 in) outside

A quick-start

facilites. The

unit.

of these

a real

each chamber proto-type

size

under

six

actual

confirmed

the

following: -

dimensions

of the flash chambers.

-

dimensions

of the orifices

-

efficiency

of the vapour-brine

-

values of heat transfer

Shuaiba South The

two

previously

with

four

These demanded than

more

stages,

were

ejectors.

The

employed, temperature

at

of

Shuaiba

5.0

ratio

units

resistance

air

and

were

characterized

in

M.E.&W.

by cacade

of by

the

from the first gases produced

control

using

non-condensing

which

and medium

they

are

gases passed

temperature

in each

parts

were of 23

relative

smaller

The trend of

the

to use

evaporator

new practice. during

stage were orifices.

a

purity of

the

flashing

stages by means of the air

efficiently, through

the

specifications.

South.

produced

and final

extraction

which

distillate

by their

different

gases

units

to

and a brine heater.

units at Shuaiba

materials

added

of Japan and consisted

of 8 and a guaranteed

non-condensible

extracted

were

The

South.

by I.H.I. stages,

MIGPD

the by now well-established

to the other

Noncondensing

final stage discharge

(demisters).

The pumps were all motor driven as a standard

ingress

operation

plants

a performance

30 ppm.

corrosion

The

capacity

3 heat rejection

size compared

continued.

a

in 1975 were manufactured

The two units satisfied

physical

separators

coefficients.

each

mentioned

heat recovery

less

chambers.

'A5' & 'A6'

plants

commissioned

between

vent

zones and discharged

accumulated

in the

In order to perform a

by-pass

pipe outside

from

method the

is

high-

the system via

28 the final ejector

Sea

stage(7).

water

was

but instead

condenser,

not

used

distilled

as the

cooling

water produced

water

of

steam

in the evaporator

was

used. The tubes outside 44.50 mm sections

(1.75 in

diameters

were 25.41 mm (1.0 in), 31.75 ma (1.25 in), and

1 in the heat input, Proto-type

respectively.

heat

testing

rejection,

was carried

and

heat

recovery

out before final design

could be accepted.

Ooha East

'Al - A7'

The seven plants units

(Al-A31,

which

were

period

were erected

while

stage

manufactured

by

II

over two

stages.

Stage

I consisted

of four

units

(A4-A7).

consisted

I.H.I.

of

Japan

were

of three

The plants

all commissioned

over the

1978-1979.

The

capacity

of

capacity

was

capacity

operating

performance

each

installed

ratio

each consists

unit

was

6.0 MIGPO, Since then

in Kuwait.

at low temperature

first

time

the standard

distillate

stages,

purity

such

a unit

desalination

(90°C) is 6.0 MIGPD.

of 8 and guaranteed

of 23 heat recover

the

of less than

3 heat rejection

unit

The units with a

stages,

30 ppm,

and a brine

heater. The plants

design

accommodating capacity. emphasis the

satisfied

was paid

included

however

stronger

all the main

to better

demisters

instrumentation

the

condenser

venting

and

the

vented directly above system

of

last

specifications

related

features

material

frames

and

to the higher

in different

fixing

as,

product

so far mentioned.

selection better

as well

More

parts of and

arrangements,

and control.

Up till now with plants of capacity involved

M.E.&W.

all the necessary *design aspects

The design

unit,

enhanced

basically

the first stage

of

from 1 upto 5 MIGPD, the venting

and second the

upper

to the last stage. However,

was inadequate

and another

to the last stage was introduced(81.

stages deck

directly

(possibly

stage

for bigger units-of

venting

line from stage

This modification

system

to the ejector

enhanced

No.141

is

6.0 MIGPD, the No.6 directly the efficiency

of the unit.

Shuwaikh The Shuwaikh during systems.

'Ill, D2 & 03' three

plants

Power 1982. Heating

manufactured

Generation They

and Water

utilized

the

steam was supplied

by

Babcock-Hitachi

Production existing

sea

K.K.,

Station water

from the existing

and

were

added

to

were coanaissioned

intake

and

discharge

power generators.

29 Each unit was designed ratio

for a product capacity

of 8 and a guaranteed

unit consisted

distillate

of 21 heat recovery

purity

of 6.0 MIGPD,

of less than

30 ppm

3 heat rejection

stages,

a performance TDS.

The

stages and a heat

input section. The design

of the units followed

and was basically differences

did exist regarding

extent

gases,

specifically

of

is carried

of the unit.

of

filteration

is passed

venting

oxygen of

the

oxygen content achieved

deaerator

by

is vented

stage

to the

(No.241

in cascade

while

through

vent

which discharged second

start-up

and from there

input

rejection sections

and

heat

section.

of

sea water

to the last stage

water

rings

the

air

make-up

packed

Further

sodium

through

and the

after

deaerator

reduction

bisulphite.

ejector

of The

system.

The

the vent condenser.

The

1st and 2nd stages are vented

13th and 19th stages are vented to stages

The 24th stage

are vented

which

in turn

to the next

is vented

to the inter-condenser.

to the atmosphere.

tubes

outside

recovery The

are made

alloy

to the first

The inter-condenser dischargd

The starting

diameters

sections

tubes

(66% Cu,

and

material

Doha West

30% Ni,

out of aluminium

boxes were made of carbon

to

ejector

the

is

after

is used for

were 31.75

for

the

38.10 mm

(1.50 in) for the

mm

in)

(1.25

heat

input

section

for and

the heat rejection

is now an improved

2% Fe and 2% Mn), while the rest of the

brass

alloy.

The

distiller

shell

and water

steel.

"Phase I"

Doha West,

phase

which were erected Italy,

of

and stages Nos.1 & 2 of the heat recovery

copper-nickel tubes

sea

to 70 ppb.

intermediate

ejector,

selection

purposes.

The heat transfer heat

stage

deaeration

pall

by

The 7th,

some

for this unit called for the

injection

pipes.

stage ejector,

condenser

is reduced

stage ejector

the

material

attached

the

polyproplene

1st stage

vented

to the

so that chamber

is accomplished

However

tubes(9).

whereby

the

specifications,

of non-condensible

general

specifications

the

to the inter-condenser.

the last stage

through

is

designed

deaerator,

is vented to the first

brine heater directly

were

the design

an external

where the dissolved

deaerator

to the heat transfer

out in an integral

However,

utilization

dissolved

detailed

'A' plants.

and venting

and

treatment,

so far mentioned

feed

M.E.&W.

the deaeration

chemical

with respect

All units make-up

closely

similar to the design of Doha East

I involved

the

by a joint venture

were commissioned

erection

of four

plants.

between

Reggiane,

AMN,

over the period

1983 - 1984.

These

plants,

and TMT, all of

The units, each with a

30 rated capacity maximum

of 6.0 MIGPD, were designed

distillate

heat recovery The design and was

provide

units

in many

(10,111.

flexibility

30 ppm TDS.

3 heat rejection

of these

similar

improvements

purity of less than

stages,

stages,

followed

respects

with a performance

closely

the specifications

to previous

operation

ranging

Each unit consisted

of 21

and a brine heater.

unit design

To allow ease of operation of

ratio of 8 and a

with

of M.E.&W., certain

added

these units were designed

from

70

-

110%

of

rated

to

product

capacity. Before the final design was approved, design parameters

on a proto-type

these units is conceptually

the contractor

plant

a separate

(11).

as it is joined physically

achieve

general

a better

polypropylene remaining A

pall

concept,

namely

in the design

had been utilized tube cleaning

different

the

in Kuwait.

was

modes;

added to Doha

unit

while

desulphation

has

been

top

to

with

scavenge

any

System

was

Taprogge

unit

is provided

with

of a strainer

and heat recovery

brine

heater

a ball

section,

The system was designed

of

tubes

a

to have

only

and

section.

brine

stages

decarbonator, desulphation

& Water

Doha West Phase

Production

Station

unit with a rated capacity

at high temperatures

designed

to

operate

of 121,

temperature at

130

utilizing

of 1.0

acid treatment

to

here that this is the only unit

both containing which

three

different

of 121°C is achieved

and

modes;

138°C

includes

the

with

at

a

Operation

acid treatment

utilization

ratio of 10 at 121°C and guaranteed

30 ppm TDS,

and a brine

in

130 and 138°C respectively.

of

a

to the acid treatment(l2,13).

a performance

unit,

Power Generation

supplying

acid treatment.

unit in addition

The unit with

by the companies

It should be recalled

operation

purity of less than rejection

pumps.

cleaning

East

top brine temperatures

at a maximum only,

used

cleaning

principally

This experimental

to operate

scale formation.

in Kuwait which utilizes The

also

in order to

is packed

'A8'

MIGPD was designed

maximum

deaerator

part

This was the first time this system

Each distillation

and two recirculating operating

and coannissioned in 1985.

prevent

is

balls

units.

This unit which was manufactured I plants

vacuum

bisulphite

foam

of these

of both brine heater

Doha East

in the design of

it is an integral

to the main distiller

The

system. The system consists

ball collector,

cleaning

Sodium

although

all the

oxygen.

new

introduced

two

arrangement.

rings.

The deaerator

vessel,

of the Evaporator

had to verify

consists

heater.

of 25 heat recovery

The

design

includes

pall ring type packing.

consists

of four

columns

distillate

stages,

a deaerator

3 heat and a

It also incorporates containing

anionic

a

resin

31 Two of these

beds.

columns

are in operation

two are being regenerated(l4). considerably

The material

at any one time while selection

in order to combat the expected

the other

of the unit was enhanced

increase

in corrosion

attack due

to the use of the acid treatment. This

unit

treatment

is

to

be

used

to

(high temperature)

evaluate

MSF

in comparison

distillation

with

utilizing

anti-scalent

acid

additives

(low

temperature).

Doha West

"Phase II"

II

Phase

of Doha West

consists

of 12 units each with

7.2 MIGPD. The plants were designed, of three Japanese

companies.

Heavy

and Mitsui

Industries

period

units

were

polyphosphate additives,

& Co.

designed

additives with

respectively.

a

consists

Engineering

concepts

operate

Co.,

Mitsubishi over the

of Doha West

thing regarding

that

paid

to

stages,

phase

The enhanced

The

steel,

using

ratio

special

of

8.0

an

II

enhanced

material

materials ceiling

Nos.19

- 23

plants

polymer 8.65

from 6.0

Each unit basically

stages,

incorporates

over the years(l51.

and

selection of

a brine heater

all the major design But perhaps,

selection no doubt

of the Nos.1

stainless

from

emphasis

and the added

in stages

316L

are made

given

to

corrosion

add

to

the

will increase

surfaces

316L

protection

flash

could

chambers

protected

with

epoxy

orifices

plates

are

remaining

coating. all

made

- 12 & 24 are made

steel,

while

stainless

stages

The flash from

of

316L

boxes

from

steel.

brine

from carbon

The front

in addition

stainless

the

the ceiling

steel.

are made

be clearly

and

plates in and

rear

steel.

Nos.1 - 6 & 24 are made from 316L stainless

in the

units

the life-span

plates in stages Nos.1 - 6 & 24 are also clad with 316L stainless bottom plate in stages

the most

costs considerably.

construction

plates

the

material

as it will

future maintenance

but are clad with

above

using

and

of the unit to be increased

3 heat rejection

selection

it is advisable

the unit and reduces

heater.

(llO.O°Cl

(90.56"C)

the design of these units is the much more attention

material

Although, costs,

in the

temperature

performance

the production

that have been introduced

control.

low

equipments.

noticable was

at

to 7.2 MIGPD at high temperature.

of 21 heat recovery

The design

capital

to

and high temperature

This enables

and auxiliary

The

of 6.0 -

by a consortium

All the units were commissioned

corresponding

MIGPD at low temperature

stages

These were Sasakura

a capacity

and erected

1984 - 1985.

The

seen

manufactured,

carbon

The

steel also. steel

and

to the weirs

and

Tube

supports

in

32 - 6 are also made for 316L stainless

stages Nos.1

boxes are concerned,

Nos.1

- 4/5 though made

steel.

As far as the water

of carbon

steel,

are clad with

90/10 Cu-Ni. A large

number

installed chambers flash

to

of sacrificial

provide

cathodic

and water boxes,

chambers

anodes

protection

protection

and protection

made

out of iron of

coated

of stainless

of copper

and zinc metals

mild

alloy tubes

in

steel

steel against against

flash

pitting inlet

are

in the

attack

in

the heat exchangers.

V

DESIGN FEATURES OF MSF PLANTS

SPECIAL

The latest design for

plants

suitable over

with

well

the

last

thirty

worthwhile

to

have to

available

that

materials

by the

Kuwait

that

These specifications vast

MSF

must

experience.

special features,

plants

have

the

be

have evolved

accumulated

some of the design

all

21 They

are

and reliable

of fresh

design,

types of material

production

be stable

source

sound engineering

capital

enriched

years,

and

units in Kuwait calls

it is

following

main

features:

1) They only

parameters

Gulf environment.

in some details

record

of MSF distillation

established

for the Arabian

Before we discuss

general

specifications

water

ensuring

of construction part

of

a

of electrical

and operational

in Kuwait.

adequate

dual-purpose

they

are the

can be guaranteed

transfer

system;

Dual-purpose

because

This

heat

and proper corrosion

power. costs.

in operation

areas,

by

adequate

allowances.

the

plants

other lead

part

being

to saving

the

in both

The systems designs must allow for flexibility

in operation. 3) They are based on the cross-tube an

arrangement

recirculation

is

superior

to

on balance,

5) Until

recently,

temperature

of or

90°C.

similar

scale deposits. brine

additives.

arrangement.

are motor driven

It

This

is

was

plants

llO"C,

believed

designed

dictated

anti-scalent

of

They

that such

are also

of the

design.

as experience

has shown that,

drive even for big auxiliaries

pump.

all plants were

Recently,

temperature

as it is believed

to the once-through

motor drive is better than turbine

like the brine recirculation

compounds

long-tube

type which is superior

41 All the plant auxiliaries

arrangement

by that

by

additives

to operate the

are

fact

used

have been designed utilizing additive

special treatment

at a maximum that

for

the

to operate polymer is

brine

polyphosphate prevention

of

at a maximum anti-scalent

superior

to

acid

33 treatment.

However,

an experimental

the aim of evaluating overall

operational

6) The level

of

each

reliability

maintenance

and

functional

shall

for operation

latest

distillation

plant

neat

and

shall

arranged

systems

The evaporator

operation

between

provide

with

affect

on

the greatest

operation

into

provides

and

account

the

ease of access

of each unit shall be capable

of

70 to 110% of rated capacity.

specifications

and requirements

for of

taking

which

(16)

demand

that

plants must satisfy many requirements.

design parameters

recently,

and its

convenience

orderly

of the various

M.E.&W.

acid treatment

availability,

and maintenance.

stable and continuous

The

be

of

and plant life-time.

distillation

and

requirements

plant has been commissioned

aspects

reliability

design

of

different

the

design

of

the

Some of the most important

are the following:

1) Rated capacity The distillation sea water

plant shall have the capacity

in Kuwait under the highest

The design

must allow

full rated

output throughout

water temperature

in winter

is 14°C.

enable

the rated

product

increasing

anti-scalent

additives

2) Performance

entrance

is produced

conditions

while

the

steam

sea

in the design must be made, to when

depends mainly

ratio is considered

3) Brine Top Maximum

in order

to attain

however,

tendency be made,

ratio of 8,

of low

heater

after

pressure

using

special

of 110°C.

i.e.

steam

eight Kg.

having

any desuperheating water)

the capital

consumption

performance

additive

from

The minimum

at top brine temperature

desuperheating

ratios,

ratio

It is desirable

one Kg.

to the main (including

performance

to

the year.

to 7.2 MIGPD

with a performance

per

With higher performance

has

6.0 MIGPD,

of 32°C in summer.

Ratio

as total condensate

increases

Allowance capacity

to enable operation

The plant shall be designed of distillate

to produce

sea water temperature

design

and measured

into the main heater.

cost of the distillation

decreases.

Selection

on the steam energy

costs.

of

the

plant optimum

The most optimum

to be 8.

Temperature

to have the brine maximum higher

plant

efficiency

for scale formation bearing

in mind,

and the temperature

temperature

and a reduction

increases

the

as high as possible

type

too.

and

that can be attained.

Hence,

dosage

in capital

cost,

an optimization

of the anti-scalent

34 With brine

polyphosphate heater

operation which

is

as

limited

above

to

the maximum

represents

brine

temperature

represents

hydrolysis

this temperature,

are used,

This temperature

which

90.5'C,

leads to loss of effectiveness

additives

maximum

the

treatment,

the

brine

the

limit

for

of the polyphosphate

temperature

occurs

If special polymer

and sludge formation.

the design maximum

leaving

safe

could

be raised

to 110°C.

brine top temperature.

4) Brine Concentration In order

to limit

scale formation,

ratio of the recirculating With an average

1.5.

to a recirculating

brine

temperature

concentration,

which

is the

is kept at around

TDS to the sea water TDS,

sea water TDS of about 45000 ppm, this ratio corresponds

brine TDS of 67,000 ppm.

5) Brine Recirculation The

brine

the brine

Ratio

recirculation of 9O"C,

ratio

is around

for

plants

operating

In plants

12.67.

at

where

a maximum

brine

a higher temperature

could be used, this ratio will be lower.

6) Brine flow Rate per Width of the Flash Chamber The brine mass flow rate 810,000 to

Kg/hr/m

control

the

at 100% of rated brine

equilibrium

losses.

temperature

will

chamber while

per unit width of the flash

levels Operation

require

operation

This

capacity.

in

the

at

higher

at higher

flash

110%

brine

chamber

is mainly

chambers

of

rated

flow

rate

temperature

and

necessary to

capacity per

is limited to

and

unit

in order

minimize same

width

at 100% of rated

nondesign

of

flash

capacity

will

result in lower brine flow rate per unit width of flash chamber.

7) Fouling

Factors

The performance and

adequacy

recovery,

of

of the design

plant

of

depends

the

and heat rejection

heat

mainly

sections,

perform

its duty as per design requirements. as expected,

the

duty

of these

the whole

sections

the correct the

heat

performance input,

each

of the plant

other

towards

the

heat

is equipped

If any of these sections

performance

complement

for

such that each section

perform

then

upon

exchangers

to

does not

is affected overall

as

plant

performance. In the design of MSF distillation margin

of

scale

build-up

for scale prevention.

to take

Therefore,

based on this fact by providing

plants in Kuwait,

place

is made

the design

allowance

despite

for a certain

the use of chemicals

of all the heat exchangers

extra surface area to compensate

are

for the above

35 fouling

by

The

scaling.

fouling

derived

from past experience

fouling

factors

The above formation hours

and they vary from one section to another.

(average)

Section

fouling

0.004826

(average)

factors

higher

acid cleaning

are

These

m*k/W

0.005678 m'k/W

ensure

on the heat exchanger

and

in the design

0.008517 m2k/W

Section

Heat Rejection

to be considered

are:

Heat Input Section Heat Recovery

factors

adequate

extra surface

tubes and thus ensure

average

production

will arise.

Moreover,

rates

longer number of running

for the plant

it will ensure

to allow for scale

before

any need for

longer life for the plant

due to less total number of acid cleanings.

8) Number of Stages The design

must include

ample and adequate

number of stages

so that the unit will operate

its long service

life without

not be less than 24, arranged

abnormal

heat transfer

surface

in a satisfactory

stoppages.

areas and

manner

during

The number of stages shall

in two tiers.

9) Feed Water Treatment The feed make-up after

screening

additives

water to the unit is treated

with

are used,

3.20

With the use of special resulting

about llO"C, 7.2 MIGPD.

To prevent

an anti-foam

In

section

heat

intake screens.

to

polyphosphate-like not

exceed

in production,

in the stages,

90.56"C.

could be raised to i.e.

from 6 to

it is necessary

to add

Chlorine to the

deaeration

of

recirculating

sea water where

is carried

to

in

intake

sea

is injected

unit

In addition

system

the

the

brine

make-up to

reduce

feed, the

sodium level

of

zero ppm.

in the

exchangers,

supply

intervals.

When must

this temperature

20% increase

occuring

complete

injected

fouling

chlorination. water

strainers. temperature

additives,

in around foaming

ensure

to is

oxygen to practically Marine

polymer

size

brine

additive

agent.

order

bisulphite

mm holes

the maximum

with an anti-scalent

system

water

is

by continuous

addition

to

high

the chlorination, out

using

trash

and

in the

flowing, dosing rate

heat rejection controlled

by

of 2 ppm to the sea

shock

screening

racks,

is

of

dosing

for

sea water

stationary

short in the

and travelling

36 101 Heat rxcnangers

Tubes Sizes

All heat exchangers

tubes

shall

The wall

31.75 aua (1.25 in).

not

have

thickness

internal

diameters

of the tubes

shall

of

less than

not be less than

1.22 mm (18 SWG). With

smaller

clogging

tube

sizes,

of the tubes

formation,

with

there

debris

which in turn induces

11) Brine & Sea Water Velocity The brine

and sea

water

is

a

tendency

and foreign

corrosion

partial

or

complete

and accelerated

scale

damage of the tubes.

In Heat Exchangers

velocity

of

material

through

Tubes

the

heat exchangers

tubes

shall

not be less than 1.83 m/set and not more than 2.13 m/set. With

low velocity and

increased, requirements

through

on the

the tubes,

other

will increase

hand,

considerably

high

formed

on the inside

to failure

of these tubes and outages

of the plant.

is

the

most

ensuring

optimum

steam

supply

giving

heater

suitable

reducers.

internal

The design (10

prevent

the

leading

the above range of

of

safety

and

in

the

superheated

at

approximately temperature

by the necessary

even distribution

plates and baffles

by

desuperheaters

of steam over the tubes,

are used.

At The Heater Outlet

brine pressure

Psig)

of damaging

of tubes

exceed the brine outlet

is controlled

To ensure

impingement

13) Brine Pressure

barg

Thus,

margin

is slightly

not in any case

more than 14°C. This temperature and pressure

enough

surfaces

is

power

To Brine Heater

to the

and should

zero barg,

electrical

long life of the tubes and the plant.

12) Steam Inlet Temperature The

scale formation

and there is a possibility

protective

velocities

for

velocities,

the normal

meanwhile

coating

the tendency

with

at

rated

phenomenon

at the heater outlet

output

of the

local

boiling

of

plant

should not be less than 0.69

and

to take

shall place

be at

high any

enough

part

to

of the

heater or in the connecting

pipe, or in the brine entry box to the first flash

chamber.

is

operation. the

extra

discharge

The

above

limit

It can be affected head

required

and

by proper by

reliable design

suitably

and

safe

limit

of the brine

designed

orifice

for

plant

pump to provide plates

in

the

Orifices

The design of the evaporator from one stage to the next plant

ensure

pipe and brine inlet box to the first flash chamber.

14) Brine & Distillate

the

to

for

all

rates

is such that the flow

stage

is automatically

of outputs

by ensuring

of brine

and distillate

self-regulating correct

design

throughout of orifices,

37 and weirs.

nozzles,

All orifices,

20% above the flow required

nozzles

and weirs must be designed

for the full rated output,

with 15-

in order to control

the

levels in each stage. Brine

flashing

orifices losses

shall

devices

provide

through

the

difference

pressure

loss through

pressure

difference

orifices

will

first

Therefore,

stages

the

is

prime

brine

minimum stages

and

to

for the higher temperature stages

in excessive

in the higher

Brine pressure

where

provide

the

higher

stages where the

Incorrect

is high.

splashing

design

of

temperature

stages and the performance

brine stages

of the plant

considerably. difference

stage

and

is considerably the

vacuum

the above high pressure

high between the brine before entry

prevailing

in

the

reduction

exert high pressure

difference

and

at the

same

loss. The design

time

first

flash

chamber.

to the first stage is considered in order

The design of the brine entry orifice

of pressure

with

small

of the brine entry to the first stage and to control vapours.

importance.

temperature

very

special design brine entry orifice

to overcome

of

of

lower

is

of the lower temperature

The pressure the

the

the orifices between

design

flashing

for

between

result

will be affected

to

efficient

orifices

pressure

and flooding

(orifices)

to limit the velocity

brine carry-over

with the

of stage No.1 allows two stages change

of direction

of flow

shall ensure the absence of hammering

to and

local flashing. The distillate

transfer

ducts with suitable distillate

levels

from one stage to another

weirs/orifices in each

stage

and adjustable can be adjusted

must be through

mechanisms

adequate

in order that the

from the outside,

while the

unit is running.

151 Brine Level Brine correct

level

in the stages

must

design of brine orifices

per unit width

of the flash

result in an adequate lower losses

free height

specifications

This is ensured

and weirs and by limiting

chamber

to within

and consequently

from

by

the brine mass flow

acceptable

of the demisters

in the flash chambers

plant. The design

be as low as possible.

limits.

This will

the brine surface

better

performance

and

of the

call for a brine level of about 0.5 m.

16) Oemisters Demisters

of not less than

stage for efficient bottom support accessible,

scrubbing

frames

detachable,

securely

152.40 mm

thickness

of the vapours. attached

shall

The demisters

to each other.

and easy to examine

be provided

and replace.

in each

must have top and

The demisters

must be

38 17) Demister The

Height

distance

the

vapours

produced

level to the bottom

surface

of the demisters

the distillate

purity.

out with vapours design

High distance

travel

from

is important

brine maximum

to the control

allows some of the heavy droplets

to fall back to the flashing

specifications

the flashing

call for a demister

brine solution.

of

carried

Therefore,

the

height from the bottom of the stages

of not less than 2.13 m.

18) Vapour Release The

release

surfaces

shall

vapours. this

Velocity

velocity be as

The maximum

is ensured

by

of

the

produced

low as possible vapour release

providing

vapours

from

to minimize

velocity

adequate

the

brine

flashing

carry-over

brine

with

shall not exceed 4.0 m/set,

cross

sectional

area

(length

the and

& width)

for the flash chambers.

19) Vapour Velocity

Through

The vapour velocity is the

final

vapours

after the demisters

condensation

stage

of

scrubbing

velocity

the last

stage.

different

flash

Vapour paths

This

is ensured

the

vapour

ensuring

20) Distillate

by

The design of the evaporator

of the

limiting drop

better performance

and

distillate

measured

a net

transfer

maximum

purity

at distillate

and over-load brine

permissible

with the

purity after

must be restricted,

the area of vapour existing

increase the

vapour

paths

specific

velocity

through

the

in the

volumes.

as the temperature

vapour

losses

so that it is

than 9.0 m/set in

of the

through

the

demisters

are

of the plant.

shall prevent the carry-over

at all rates of output.

tray and cascaded

have

out

product

tubes surface.

through box

The distillate

from

the

last

stage

condition

of

pump

not more outlet

sea water

concentration

in the flash chambers.

30 ppm

a complete

of the product

as total

at all loads up to full

and at varying

temperature,

than

ratios

of brine droplets

shall be collected

each stage ensuring

first stage of the bottom tier. The total distillate shall

carried

as it

Purity

with the vapour distillate

to the

stage lengths

pressure

salts

stage and not higher

by varying

according

Moreover,

decreases.

demisters,

the demisters

in the first

and accordingly

the

the distillate

at the condenser

through

chambers

shall be as low as possible

and

will determine

of these vapours

The vapour

minimized

the demisters

vapour

not higher than 2.0 m/set

stage

Demisters

through

top tier

to the

in the last stage dissolved rated

temperatures, and

in a

water seal

highest

solids

production

and with the brine

levels

39 21) Deaeration The

feed

condensible minimum

of Feed Make-Up make-up

gases

make-up

to remove sea

carbon

water.

shall contain

water

A suitable

levels.

provided

sea

is deaerated

The

suitable

containing

to reduce

integral

deaerator air and

dioxide,

deaerator

packing

shall

contain

shall ensure

dioxide

(CO21 that may be present. by the injection

ensure

minimum

suitably

corrosion

the

levels

to the vent condenser

vacuum

type

system.

oxygen

The design of

in the plant.

oxygen

is important

The deaerator

and to the major ejector

shall not

(02) and any carbon

of dissolved This

and

spray nozzles

leaving the deaerator

bisulphite.

shall be from the

counter-current

steam injection

The level

of sodium

under

non-

gases to

non-condensibles

100 ppb of dissolved

reduced

of

of these

a system of feed water

that the feed water

at any time more than

quantities

working

other

be of

material,

near the top of the tower and stripping the deaerator

dissolved

the concentrations

is further in order to

shall be vented

system.

22) Venting Venting of non-condensible heat exchangers. form

an insulating

the

heat

through

the

non-condensible

gases

from

to seventh

chambers

demands

chambers

tubes

thus

affecting

venting

of each

and when present

reducing

considerably the

overall

and rapid extraction

stage

and minimizing

that, the first flash chamber,

(cascaded),

to the steam ejector flash

in the design of

of

non-

around the tubes is of prime importance.

specifications

flash

and

efficient

heat exchangers

gases movement

The design

remaining

tubes,

factor

conductivity

over the heat exchange

of the plant. Therefore,

condensible

directly

blanket

transfer

performance

gases plays an important

The gases have very low thermal

and the brine

condenser

shall

heater

shall

or by any other approved

be vented

in cascade

and/or

the second be vented

methods.

The

in groups through

the ejectors.

23) Evaporator The

shell shall 2.07

barg

internal plate

Shell

structural

design

be capable hydraulic

height

pressure,

of the

of top deck

of the

of being

evaporator completely measured

evaporator

(inside

from

to inside)

shell filled

at

the

bottom

excluding

must

be sound.

The whole

with water

and subjected

bottom

the

plate

of

of

bottom

stiffeners

shall

shell.

to The

deck

to top

not

be less

than 8.3 m. Each

stage

maintenance, replaceable

shall such

internal

shall be placed

be that

provided it

will

equipment.

at the opposite

with be

access

possible

The manhole

door to

for

remove

door for

entry

side of the distillate

duct.

inspection and into

install

and any

the stages

The distillate

40 the brine

duct in each stage,

and distillate

inter-connecting

from top

boxes

tier to bottom tier,

and the brine entry box to stage NO.l, shall be provided

with

Permanent

access

doors.

and

adequate

venting

points

also

shall

be

provided.

24) Heat Exchangers The

design

avoiding

Water Boxes

of

the

turbulence

may collect.

water

boxes

and stagnation

Even distribution

water boxes shall be easily provided

Each

distillation

duty

air

ejectors

main

heater, at

points

necessary

removable

shall

gain

the

through

areas where

from the outside, inspection,

and man-holes

cleaning,

box

sludge The

shall be

and maintenance.

and Each

heat set

from

with

rejection of

air

sections

ejectors

independent

Each

quantity

gases

be

provided

air ejector

of non-condensible

full

from the

and to maintain

must

The condensers

condensers.

the evaporator.

calculated

duplicate

of air and non-condensible

tube single-pass

product

150% of the maximum

flow

or low pressure

be provided

the removal

load.

straight

by distillate

smooth

& Condensers unit

for

heat

full

ensure

of water in all tubes must also be ensured.

for each water box to permit

25) Steam Air Ejectors

vacuum

must

design

with

the

shall be cooled is designed

gases

for

released

by

the sea water feed make-up. In addition

to the duplicate

shall be provided up purposes

main air ejectors,

for each unit,

capable

one quick start air ejector

of venting

the whole unit for start-

in not more than two hours.

26) Pumps The general be

in

such

a way

dismantling directly

heating,

at a minimum

facilitate

without

continuous,

or noise.

maintenance

All pumps

motor,

supports,

shall

of

pumps

conditions

have strength,

of

is

avoided

and metal thickness

operation

at fouled

without

speed gears. undue

the

condition.

ensure

cavitation

Pumps casings

to assure

alignment. process

that

characteristics

of loading.

sufficient

The plant design must include the following

possible

All pumps shall be designed

shall

and

stable under all conditions

weight,

accurate

loading

impellers

least

at constant

must be as high as possible,

over efficiency.

and

the

etc. shall

or multiplication

safe and reliable

Though efficiency

casings

with

piping,

be driven

reduction

110% of full rated product capacity

pumps must remain

maintain

as to

shall have priority

design all

of the pumps, motors,

breaking.

must ensure vibration

robust design

under

so

and joint

from AC electric

The design

The

arrangements

pumps:

of the shall

long life and

41 a) Sea Water Supply

Pump

At least one sea water The

unit. head

capacity

at no flow

spindle

supply pump

of each

shall

not

b) Brine Recirculation one brine

shall not be less than

exceed

4.9

The

bar.

pump

12500 m3/hr

shall

be

of

and the vertical

70% of full rated vertical

spindle

capacity

of service

for each unit.

of providing

unit.

If

not less than

The pump shall be of the

capable

of performing

its duties

having due regard to the temperature,

density

brine.

Pump

One distillate

pump for each unit shall be provided,

the full rated output

of the evaporator.

to

the

distillate

capable

The pump discharge

header and to the distillate

connected

systems.

shall be provided

of each evaporator

heat of recirculating

c) Distillate

distillate

pump

each pump must be capable

axial or mixed flow types,

under all conditions and specific

Pump

recirculation

two pumps are provided,

be

for each distillation

axial or mixed flow types.

At least

to

pump

shall be provided

make-up

main

supply

The pump shall be of the vertical

header which line

spindle

and

of delivering

is connected

to a

are respectively

the

boiler

make-up

axial or mixed flow types.

d) Heater Drain Pump The heater drain

pump shall

be capable

of the condensate

from the distillation

of the horizontal

type.

e) Brine Blow-Down

to ensure

pump shall be provided

that

the

other pump, create vortices the last flash chamber. shall be made blow-down

from

pump

the full

The heater drain

rated output pump shall be

Pump

One brine blow-down be taken

of delivering

unit.

suction

of the pump does not interfere

or prevent

Suitable

for each unit. Precautions

efficient

connections

the recirculating

is out of service.

brine

mixing

with

of the feed make-up

with necessary pump discharge

The pump shall

shall

isolating in case

any in

valves

the brine

be of the vertical

spindle

axial or mixed flow types. f) Sea Water Recirculation At least temperature velocity

Pump

one pump for each and

through

to

ensure

unit

minimum

the heat rejection

shall flow

be provided, necessary

tubes.

to

to maintain maintain

sea water

the

required

The pump may be of the horizontal

type. g) Chemical Pumps

Dosing

required

Pumps

for chemical

dosing

shall

be of

the positive

displacement

type with variable

stroke to enable varying the dosage of chemicals

ppm of the make-up

feed.

h) Other pumps such as sump pit pumps and bearing

cooling

from O-6.0

pumps, etc.

42 27) Piping & Pipe Fittings The design vapours, control

must

air,

include

valves,

safety

hangers,

supports,

all the necessary

with the necessary

etc.

valves,

etc.

piping

expansion

for steam,

by-pass

steam traps,

to ensure

for each unit,

water,

isolating

joints,

lines,

drains,

a complete

gas,

valves, pipe

and efficient

installation.

28) Materials

Selection

Materials withstand

within

service

in the operation ensure

& Protective

the

conditions.

is expected

maintenance or/and

after

This

selected selection

plants.

service.

carefully

In certain

we

have

to

be

suitable

to

is based on our long experience

The material

selection

is designed

parts of the plants,

or in case of some areas which

construction,

supplementary

The material

Systems

are

of distillation

long and reliable

corrosion

plant

opted

are not

for

high

to

where high

accessible

for

quality

materials

plant many

components

section,

and in the

protection.

selection

for some of the distillation

are as follows: a) Heat Exchange All tubes first

and

second

cupro-nickel

stages

input of

section,

the

heat

alloy with a chemical

2%, and Manganese recovery

Tubes

in the heat

2%.

heat rejection

recovery

analysis

The condenser

2%.

shall

662,

tubes in the remaining

shall be made of aluminium

section,

76X, Zinc 22%, and Aluminium

section,

of Copper

be made

Nickel

30%,

of

a

Iron

stages of the heat

brass with an analysis

All tubes are of 18 SWG thickness

of Copper equivalent

to 1.22 mm. bl Heat Exchangers Tube plates

Tube Plates & Supports

in the recovery

and rejection

Brass of not less than 38.10 mn thickness. tube plates

and both ends shall be flared.

sections Tubes

Tube

supports

of

spaced at required and to maintain

suitably painted

intervals

adequate shall

shall

be made

be expanded

of Naval into the

The tube plates of the brine heater

shall be made of Naval Brass and have a thickness

19.05 mn and suitably

shall

material

be provided.

in order to prevent

of not less than 75 mm. of

thickness

The tube

not

supports

less

than

shall

be

undue

tube sag and vibration

transfer

duct and the condenser

tubes configuration.

c) Distillate The distillate

Ducts, Trays & Condenser ducts and trays,

Shell

distillate

shell shall all be made of 316L stainless

steel of not less than 10 nmi thick.

If the shell walls are used as sides of the duct, tray or condenser

shell 316L

43 stainless When

steel

different

protected

doubling

plate

materials

are

such that no corrosion

d) Brine & Distillate The

brine

stainless be

of not less than connected

weir

stainless

steel

lined

distillate

orifices

be

suitably

adjusting

mechanisms

shall

be made

of

316L

used for the brine entry box in stage No.1 shall

with

steel. Suitable

shall be fitted.

shall

and Weirs

and

steel. The material

carbon

they

may take place.

Orifices

assembly

3 mm thick

together,

316L

stainless

cathodic

and nozzles

steel

protection

or

wholly

as needed

made

of

shall be provided.

shall be made of suitable

stainless

316L The

steel.

e) Demisters The demisters frames

shall

demisters contact

mesh with not less than 15.24 cm thickness

be manufactured

from 316L stainless

steel.

shall also be made of the same material. with

the

steel doubling

demisters

shall

be

suitably

for the

The stage partition

wall in

protected

plate of not less than 3 mm thick

and the supporting

All supports

with

316L

stainless

and of not less than

30 ems

width. f) Venting Venting stainless

& Splashing

baffles

Baffles

plates

in

steel of not less than

which are provided

when needed

Plates

all

heat

exchangers

shall

6 mm in thickness.

be

made

Splashing

shall be made from 316L stainless

of

baffle

316L

plates

steel.

g) Flash Chambers The evaporator of low carbon steel

surfaces

allowance

over

and mechanical The

and heat exchangers

having

of flash

not more than shall

be designed

nominal

walls

thickness

unit shall be made

content.

with

All internal

a minimum

required

and

last

flash

chamber

walls

shall

of 12.70 mm, and in any case, all walls shall have a thickness

the rest of the flash chambers, bottom plates

and walls

The remaining

flash chambers

a minimum

of each

carbon

chambers

and above

top and bottom plates,

wall

plates

0.15%

corrosion

for by

structural

minimum

corrosion

considerations.

first

allowance

shell

steel

corrosion

(sides,

shall

the four sides and

first tier ceiling

corrosion

including

of 6.35 mn.

bottom

a

of not less than 38.10 mm.

walls,

a minimum

walls,

allowance

top, middle,

interstage have

have

including

allowance

heat exchanger

plates)

and the

of 9.53 mn.

walls

shall have

In any case the thickness

and partition

For

of any

shall not be less than

19.05 lml. Protective

coating

The protective and

vacuum

quality

and

of flash chambers

coatings

must

conditions. painted

with

coats each with a minimum

All

internal

surfaces must be carried

be able to withstand surfaces

a minimum

must of one

dry film thickness

be

the temperature,

shot

primer

blasted coat

and

of 127 microns.

to

the

three

out.

moisture required finishing

44 h) Deaerator The

deaerator

shall

be made

stainless

steel and painted

to

against

guard

resistance stainless

316L stainless

material

lined

coating

packing

used

support

structure

The make-up

used to inject

internally

shall

be made shall

316

protected

from corrosion

be made

feed spray nozzles

the stripping

with

and cathodically

The

steel and painted.

cross pipe assembly

steel

The packing

corrosion.

material.

of

with protective

from

316L

and the perforated

steam shall

all be made from

steel.

i) Water Boxes The water approved

boxes

coating

shall

allowance

of 9.53 mm.

less than

19.05 mm.

connecting

piping

resin

coal

microns.

tar

be made

of mild

and cathodically

shall

paint,

self-valcanizing

adequately

boxes

rubber

of water

and the heat recovery

be given each

one

coat

primer

to

coat

a minimum

to

a minimum

an

boxes shall not be

and three film

section

total

with

corrosion

section water boxes and

dry

of the heat rejection

paint

protected

and shall have a minimum

In any case the thickness The heater

The water

steel

protected

dry

coats

of epoxy

thickness

of

127

shall be coated with

film

thickness

of

765

microns. An alternative

material

this case all water adequately resisting

selection

for the water boxes is also specified.

boxes and connecting

protected material

with internal

piping

In

shall be made from mild steel

lining or cladding

of an approved

corrosion

such as 70/30 Cu.Ni, and 90/10 Cu.Ni.

j) Brine Heater The

heater

thick,

shell

and suitably

stainless

condenser

titanium from

be made

protected.

from

mild

Venting

steel

baffle

of

plates

not

less

shall

than

be made

19 mm of 316L

steel.

k) Vent & Ejector The

shall

Condensers

tubes

of

the

vent

not less than 20 SWG thick.

316L

stainless

guard against

steel,

corrosion.

not

ejector

condensers

shall

The shell of the condenser

less than

The tube

plates

water boxes shall be made from carbon 90/10 Cu.Ni and cathodically

&

protected

9 mn shall

thick

suitably

be made

be

made

of

shall be made protected

of 70/30 Cu.Ni.

to The

steel clad with not less than 3 mm thick to avoid corrosion

problems.

1) Pumps All

parts

recirculating etc.

are

of

the

sea

water

and brine blow-down

supply

and

made from 316L stainless

with

suitable

casings,

pumps,

shafts,

steel. The brine recirculating

shall be made from mild steel. The pumps barrels shali be provided

recirculating

pumps including

cathodic

brine

impellers, pump barrel

, suction and discharge piping

protection

and shall

be coated

with

45 epoxy resin coal tar paint or an approved used

and

three

coats

each with

bitumen compound.

a minimum

dry film

A primer shall be

thickness

of

127 microns

shall be applied. The casing

of the distillate

from zinc free bronze, from stainless

pump and heater condensate

and the shaft, impeller

pump shall

and barrels,

be made

etc. shall be made

steel.

Any strainers

shall

be made

from

316L

pumps shall have 70/30 Cu.Ni cooling

stainless

The

steel.

bearings

in

coils and fittings.

m) Piping Sea water externally

carrying

coated

However,

pipes

with

sections

shall

be made

12 mn epoxy

near the

resin

evaporator

from

carbon

and encased

shall

steel

internally

and

in reinforced

concrete.

from carbon

steel pipe

be made

spools clad with not less than 3 nan thick 90/10 Cu.Ni.

Pipes with diameters

of

50 mm and less shall be made from 90/10 Cu.Ni. brine to or from the unit shall be made from mild steel with

Pipes carrying a minimum

corrosion

allowance

of 9.53 mn and shall be suitably

protected.

piping for distillate

service

shall be made from 316L stainless

be suitably

against

any corrosion

protected

29) Instrumentation Complete

running

plants

of

the

main

and

controlling

plant

at various

instrumentation

systems

They must be designed

must be supplied.

safety of the working The

steel and must

damage.

& Control

measuring

distillation

All

operating

conditions

and

for

to ensure must

the

smooth

ensure

the

staff and equipment.

instrumentation

and

control

systems

shall

consist

of

the

following: a1 Overall bl Backup

distributed analogue

digital

control

cl Data acquisition,

control

system.

system.

data logging

and process computer

system.

d) Power supply system. e) Complete

local instrumentation

f) Logic sequence 9) Announciation

and interlock

30) Tube Cleaning

operation

of

both

shall

or abrasive

system.

Systems

A ball tube cleaning tubes

system.

and alarm system.

hl Fire alarm and fire fighting

the

and control

system for all auxiliaries.

the

system which heat

be flexible,

balls or both.

input

shall be designed and

so that

heat

it will

recovery

to provide cleaning sections.

be possible

The

of

system

to use either plain

46 A complete,

safe,

reliable

and easy for maintenance

acid cleaning

system

shall also be provided.

31) Proto-Type

Testing

Over and above all the special distillation

plants,

commercial

plants

specifications

precautions

and if the Contractor having

normally

the

same

considered

in the design of our

has not tried his offered

capacity

ask for the building

as

the

and testing

offered

design on one,

the

of a proto-type

plant

of the main plant. The

proto-type

plant

order to simulate

shall

consist

shall be of the same dimensions configuration demisters venting

such

size

as

and

stage

viewing shall

height,

arrangements,

of the

inter-stage

the

Verification

at

distillate its flash

of

'Manufacturers to

requirements.

in

ducts,

heat

are

and

out

recirculating

equipments

plant

wall

dimensions,

orifices,

flash chambers

in the test, only four

and purity

of the

depending

or five

upon

stages will

flows

on the

hydraulic pump

performance

complying

with

of the distillate

and that the methods are

are carried

out.

flow

design

tests the

All

plant must

to build

are

be

"test water boxes"

and is

and

of control

satisfactory.

proto-type

such as pumps, motors,

where

their

from

flow, etc. The proto-type chambers

is required

the

ensure

is different

allow

to the main unit design

concerning

Works'

weirs,

to

vapour

carried

the contractor

brine

and

exchangers,

of that of the main plant.

of the different

the production

distillate which

flash chambers,

orifices

a transparent

are represented

design,

all auxiliary

equipments

shall have

are as per design guarantees, brine,

necessary,

verify

stages

of the main plant.

prove that

when alterations

Whenever

Also,

six stages

adjustments

considered,

to

plant

of varying

as representative

other parameters

necessary

and

of the plant is being simulated,

The tests shall

brine

it shall be one-tenth

brine flow,

Although

be accepted

six successive

plant concerning

height, trays

etc., as per the dimensions

which section

of

and

distillate

proto-type

the flashing,

demisters,

least

etc. Only, the width of the proto-type

have the facility

main plant.

at

as the main

length

that of the main plant, where One side

of

the whole number of stages of the main plant. The proto-type

fluid

dynamics.

sometimes

demanded.

etc, shall be assembled carried

design

and

out

on

these

specifications

VI

OPERATIONAL L MAINTENANCE EXPERIENCE

1) Operational The

Experience

extensive

Electricity evolved

& Water

from

gathered

and

detailed

(M.E.&W.)

the vast

specifications

for the design

experience

regarding

over the last thirty years.

experienced

team

continuously

of

project

in order

of the plants, thus ensuring

which

the efficient normally

more efficient

out under

and reliable

an

whereby

the question

bottom

flow,

chemicals

brine,

to

pressures

in

orifices commercial

two

major

of on

and brine

of

The taking

and prove

over of plant

is to

cooling

water feed,

stages have

the

flow

and water been

by internal

pressures

patterns,

boxes,

and the

established,

leaving

plates

removal

plates

levels,

plant

heat

flow streams

orifice

and

water

the

brine recirculation

The three main

concentration.

are controlled

and

are top brine temperature,

make-up

differential

observing

causes

of

the

brine

side

of

of the

heat

venting

of

loss

non-condensible

steam consumption

whenever

These tests

has over the years managed

The final setting of these orifices

increased

acid

tests must be

must demonstrate

engineers

operational

temperature

reduction

with

plants.

of

are carried

out

temperatures

is then

and

After

analysis.

in

non-

the

ready

for full

performance

are the

operation.

presence scales

the

settings

updated

out on the design

a problem.

levels,

and

are

up an

operators,

of

and venting

gases.

studying

has built

over by M.E.&W.

M.E.&W.

have

plant

team

dosing

establish

condensible

The

however,

of

and maintenance

and reliability

taken

conditions,

sea water temperature,

distillate

order

carried

and reliable

design of the plant.

temperature,

section,

in Kuwait,

specifications

the main items which can be controlled

brine

rejection

plants

Ministry

of taking over a new plant does not constitute

experienced

Initially

the

performance

stringent

not easy for anybody,

create

after

and

out before the plant is officially

are carried

the

operation

all the improvements

After any plant has been set up, carried

of MSF plants

by

Over this time M.E.&W.

engineers,

to cover

issued

production,

transfer

of

it proves

of

the

rise

heat

of the

can

gases,

the tubes

necessary.

distillation

on the

vapour

exchanger heating

plant side

and

tubes.

steam

the This

pressure

formation results

be

controlled

and proper heat

input

and

by

correct

scale control recovery

of

in a

in the heater, The fouling

and a drop in the last stage vacuum.

surfaces

non-condensible cleaning

of

gases

and

efficient

methods

sections

coupled

with

acid

The degree plant

of fouling

is being run.

that might

Operation

occur

depends

of the plant

on the manner

under

unsuitable

conditions

cause a plant to foul in a much shorter time than anticipated reducing

the

efficiency

plant fouling

of

The

plant.

operational

The inlet

will

by design,

factors

that

thus affect

to heat input section

steam temperature

the difference

between the

to the brine heater

steam and the outlet

14°C. This is to prevent

lead to rapid scaling,

2) Brine flow velocity

inside tubes

The normal design Reducing

brine velocity

this

velocity

must be controlled

brine temperatures

any local boiling

the heater tubes which

m/set.

the

are:

11 Inlet steam temperature

exceed

the

in which

of the brine flowing through

thus hindering

heat transfer.

inside the tubes ranges

to

below

1.52

so that

should not

m/set

from 1.83 to 2.13

will

accelerate

scale

brine pressure

outlet

concentration

ratio

formation. 31 Brine pressure To prevent

outlet from heater

any local boiling

from the heater

should be kept at 0.69 barg.

41 Brine concentration With should

the be

quality kept

in the tubes the minimum

ratio of

at

sea water

Increasing

1.5.

the

in Kuwait, this

ratio

brine will

mean

increased

scale

formation. 5) Chlorination

of sea water

Apart from screening to

prevent

any

rejection

section.

ineffective flashing

This

screening,

range.

inlet sea water,

biological

fouling and

chlorination

occuring

any

inside

debris

that

is carried the

might

be

of

the

present

will affect the bottom brine temperature

As a result the productivity

out in order

tubes

and performance

due

heat to

and hence the

of the unit will

be affected. 6) Chemical Until using

Treatment

a few

years

polyphosphate

limits

the

hydrolysis

top

condensers When

"HAGEVAP" many years

which

distillation

.

This chemical

9O"C,

leading

adheres

efficiency

first

plant

designed

the

operate

chemical,

this

temperature

formation

of calcium

heating

surfaces

of the

of the unit.

introduced

to

to

to

of this

as above

to the

manufacturers proved

were

The utilization

about

occurs

readily

was by

plants

only.

to

the thermal

recommended

starting

dosing

polyphosphate

sludge

or "PD8"

distillation

temperature

and reduces

MSF

originally

all

chemical

brine

of the

ortho-phosphate

ago

in was

Kuwait, a

be successful

1955 at a dosage rate of 4 ppm(l71.

the

proprietary and was

chemical mixture used for

49 It was

realised

formation

that

and at the

if

a

of 90°C, higher plant output investigations

along these

of chemicals purchasing

contains

which proved

recommended

essential

stay

additives additive

did

dosage

chemical(l81.

and mixing

compound.

used

of this

By

them,

the

The mixture

sulfonate

This mixture

a mixture

which

and 2% anti-foam

proved

as successful

since

then.

A

mixture

was

found

proper, to

be

scale formation.

abreast

prevention

chemicals

been

scale

It was during

developed

as the proprietary

has

inhibit

will result.

49% lignin

and

would

a top brine temperature

laboratories

than the original

and homogenous

to control

which

above

efficiency

rate of 4.5 ppm.

additive,

uniform

used

the constituent

49% sodium tri-polyphosphate,

the

To

and greater

proved to be cheaper

continuous,

scale

was

operation

to be as good

agent was used at a dosage as

allow

lines that M.E.&W.

in bulk quantities

end product

chemical

same time

of

and

developments

due to

not completely

in

chemical

the fact

that

prevent

scale,

which might give an improved

treatment

of

sea water

polyphosphate-based the

search

performance

for

scale control

was

on for

any

and is cost effective

new

at the

same time. Over scale

the

last

sixteen

formation

performance tested

were

as far as

(191 included

proved effective

years

many

scale Darex

40,

Another

Calnox

214 and

of 93"C,

polymer

scalent additive be superior further

In order

and Belgard

Belgard

EVN.

of Belgard

EVN,

performance

it was necessary

obtained

reliable

the

heater

EVN was initiated

at a dosage

fouling

with that obtained

additive(20).

'F' plants.

factor during

rate

during

Belgard

The next

of a new antiBelgard

EVN to

additives.

operation

between

the performance

low

additives

at a top brine

polyphosphate

of polyphosphate

instrumentation(22). temperature

polyphosphate

(231, using a dose rate of 2.0 ppm. EVN is quite

effective

as a scale

as low as 2.0 ppm.

It was also found

this trial

only far

the polyphosphate

The

its much higher unit price.

calibrated

long-term

their

P-35 was also tested,

comparison

to monitor

The short term trial did prove that additive

These

(21) confirmed

EVN was that it enabled

out a proper

data, a trial of Belgard

control

H.

with polyphosphate-based

was however

prevent

their unit price made

as the polyphosphate

long time using carefully

having

Vaptreat

Cyanamer

The trial

compared

to

determine

Some of the additives

out on the Shuwaikh

of 105°C. The disadvantage

for a reasonably After

called

to carry

to

out on this plant was for the evaluation

in performance

attraction

temperature

designed

order

however,

additive,

All the above trials were carried to be carried

in

is concerned.

but this did not prove to be as effective

trial

additives

tested

inhibition

upto a temperature

them uneconomical.

polymer

operationally

was not trial,

that

less compared

but its rate of increase

50 was also

smaller.

demonstrated

Another

105"C, thus enabling By

now

it

concerned,

trial

the capability

had

more distillate been

Belgard

EVN was superior

(6 MIGPD) running

EVN,

that

consumption that

the

EVN

high

was

when using

polyphosphate.

scale

prevention

The trial which

of

cost

lasted for a whole year was

of both additives

units

but

Belgard

also

to

factors. EVN,

effective

polyphosphate

over such a long

monitor

the

steam

The trial did reveal

chemical

compared

treatment

to

using

polyphosphate

the need to acid clean a unit was less frequent This

due to acid cleaning,

is

using two large

price

more

Furthermore,

as

out1251

capacity

unit

treatment.

damage

far

of both units and other operational

despite

Belgard

as

with one unit utilizing

EVN.

product

up to

a trial was carried

the performance

high

EVN which

due to the much

and the other using Belgard

using

Belgard

However,

devised time

on

scale deposition

to polyphosphate.

simultaneously,

not only to monitor

out

to prevent

output.

established

higher unit price of Belgard units

(24) was carried

of the additive

is very

important

and thus

longer

as it means

unit life.

than

less corrosion

Belgard

EVN is now

freedom

from scale

being used in many of the MSF plants in Kuwait. An important

feature

formation

on

attention

is paid

sludge

the

formation

output,

of an MSF plant

brine

side

of

to chemical does take

increase

an onload

input

and

heat

hydrochloric

exchanger

place

system

and this condition

condition,

which

recovery

tube

cleans

sections.

surfaces

Nevertheless,

very

if

slow

is evident

close

scale or

from falling

and high steam consumption.

To

the plants in Kuwait are acid washed

the

surfaces

For

this

of the

purpose

tubes

inhibited

in the heat 33

percent

acid is used.

Although treatment

heat

treatment.

in heat input shell pressure,

restore the plant to a clean using

the

is the comparative

Kuwait

chose

the

additive

as a means of controlling

damage and the high quality were carried

out

treatment

in preference

scale deposition,

of control

to the

acid

due to fear of corrosion

acid treatment

demands,

(26) in order to assess the applicability

some studies

and suitability

of

acid treatment.

This interest

in acid treatment

culminated

in the design and

erection

experimental

unit

A8),

the

of

evaluating 138°C.

an

operation

The unit which was recently

corrosion

rates and methods

2) Maintenance Proper operational

(Doha

using acid treatment

East

up to a maximum

commissioned

for

purposes

brine temperature

of of

will also be used to monitor

of its control.

Experience

maintenance

coupled

practices,

ensures

This leads to increased

with

good

plant

high reliability,

productivity

design

and

and enhanced

and reduced water costs.

satisfactory availability.

51 The

maintenance

planned

carried the

maintenance,

from operational An annual

problems

planned

out

period

first inspected report

when

is prepared

which

describes

far

as

is related

the

mechanically protective repaired

evaporator by water

coating

supervision

the of

engineers, Inspections from

the

before

Water

independent

VII

work

involved

far as Kuwait

is concerned,

well developed

systems

Many studies years. and

costs

of

specifications

solar

and

and silt.

METHODS

respective

strict

of

Close station

specifications.

out by M.E.&W. These

engineers

inspectors

in a position

out according

The

pipes are

contractors.

the

(WRDC).

are

to ensure

that

to specifications.

& RELATED

sea water

RESEARCH

desalination

is based on

out into the possibilities

other desalination

methods,

water.

provided It should

that the MSF method

and that Kuwait was actively

The most important

aspect of this development

is the reliability

of the MSF plants due to its

engineering

different

carried

desalination in

plant(281

supervision

of

as

design.

were

distillation

desalination

by

As

cleaned

could be given.

for both sea water and brackish

and evaluations

These covered

Electrodialysis

Centre

state some years back,

in this development.

are

a final inspection

by

follow

are carried

many studies were carried

a very mature

out

daily

must

OF OTHER DESALINATION

methods

debris

scale,

and are therefore

be borne in mind when studying has reached

out

Development

tubes

water boxes and connecting

if not all of Kuwait's

by other desalination

and formulates

data of the unit during the

condenser

carried

work

work has been carried

most,

the MSF method,

is

carried

maintenance

Resources

a complete

The maintenance

out.

for unit start-up

and after maintenance

INVESTIGATIONS Although

is

of the unit

work is finished,

approval work

of the stations,

the maintenance

all

any sludge,

After maintenance out, before

the

Each unit is

work.

concerned,

jet to remove

the

has out

all items of the unit and its auxiliaries.

maintenance

as

plants

is carried

is at its lowest.

condition

of the flash chambers,

adequately.

of

is

programme

During this inspection

all the operational

covers

general

as indicated

of the plant.

work to be carried

to the maintenance

work

the unit is carried Most

the

from

of all distillation

demand

after shut-down.

for the maintenance

The maintenance

apart systems

The maintenance

now.

work also takes into account, year which

includes, defective

of maintenance

the water

immediately

recommendations

plant of all

any

prior to the shut-down

programme

been in effect for many years over the winter

on

maintenance

out by M.E.&W. methods,

Kuwait(271, and more

commissioning

over the last 20

and included performance

recently of

a

the 60000

performance

of

0.2

MIGPD

preparation IGPD

of

brackish

Electrodialysis Compression alternative the

methods

years,

based

on

these

desalination

for

continuous

desalting Even

monitoring

of

processes

brackish

so

many

and

The general

of desalinations(30).

communities.

for 0.1 MIGPD Mechanical

and comparisons

of

suitable

isolated

specifications

unit(29),

and

technologies mainly

plant, proposed

distillation

or

of

TDS

were

these

of the

processes

waters not

for

reached over

developments

that

low

them

conclusion the

is

Vapour

recommendations

for

found

are

small to

and

be

cost

effective. Much more interest its recognized carried The

was paid to desalination

greater

out by Water Resources

studies

different result

carried

of these

brackish

water

certainly Kuwait

included

and

and

a promising in

Fund

As

far

as

programne

was

sea

and GKSS Research osmosis

in

research

plant

plant consists 0.66

different

osmosis the

Kuwait

(35)

membrane

proper

evaluation

existing

reverse

namely,

pre-treatment into the

data generated

kinds

techno-economic

needed, of

The

operational

depends

of

& Water lines,

Reverse

a as

and that

Osmosis Recently,

Osmosis mobile

problems

concerned,

a

Development

joint Centre

Research

(KISR),

of sea water reverse an

experimental

Production with

osmosis

osmosis

will

of most

study. The commercial

in Kuwait will mainly

is

Resources

a total

lines,

and

Station.

The

capacity

utilizes

of

three

hollow fine fibres,

and

for the last two years.

by the operation

evaluation

selection

far

conclusion

water Reverse

spiral wound,

of sea water reverse

in Kuwait.

as

RO(34).

for Scientific

plate and frame. The plant has been operational It is hoped that

water

establishment

production

two-stage

systems;

that

of

As

of desalination

on this

Pilot plant testing

the

separate

The

concluded

Kuwait

Water

East Power Generation

of three

MIGPD.

prompted

in

Institute

Centre of Germany.

at Doha

testing

performance.

method

brackish

by M.E.&W.

plants,

International

an of

(RO), due to (31-33) were

of 0.25 MIGPD.

between

M.E.&W.,

Kuwait

pilot

based

for 13 brackish

reverse

established

(WRDC) representing

about

establish

capacity

water

of

operational

It was

advancement

Osmosis studies

(R&D) established

RO is an attractive

has issued specifications

units each with a product

many

it was

evaluations,

to

the

Centre

overall

potential.

1976

for

by Reverse 1969,

operation

evaluating

studies

proposed or

Development

is concerned,

has

Committee M.E.&W.

out

membranes,

Starting

potential.

of this plant will enable

under

include suitable

membrane

that might

utilization

on this evaluation.

environmental

establishing

conditions

the

systems,

be faced,

level

and finally

of sea water reverse

of

insight a

osmosis

53 Research

5 Development

In order to initiate and to investigate

and advice

cooperation

with

Development

the

Centre

United

their suitability

technical

assessments

Kuwait

matters,

in close

did set up in 1968 the Water Resources

types of desalination

methods

and assessment

of

for Kuwait.

Extending

studies of different

advice

regarding

desalination

the

design

methods.

specifications

of

various

plants.

Specific

different

on all water-related

Nations,

of various

2) Techno-economic

4)

obtain

of WRDC include the following:

1) Investigation

3)

and development,

(WRDC).

The activities

desalination

research

studies

components

on

forms

various

in the

of

desalination

corrosion

plants

damage

and the

suffered

water

by

distribution

system. 5) Inspection

of desalination

plants

before

and

after

annual

maintenance

work. 6)

Active

involvement

in

the

operation

of

Doha

Reverse

Osmosis

Plant

(DROP). 7)

Performance

and

cost

used in the desalination 8)

Investigations

plumbing 9) whether

systems

Chemical

water

Organization 10)

into

the

and assessment and

sea water,

potable

evaluations

brackish,

different

damage

anti-scalent

out

analyses

to

of

ensure

on drinking

of

Engineers

The author wishes

to thank

suffered

by

water chemical

brine, distillate

carried

(WHO) standards

Training

corrosion

of different

bacteriological

is

of

additives

plants.

different

or potable. compliance

domestic

water

treatments. kinds

of

water,

Quality control of with

World

Health

water.

and

Operators

in

different

Dr.

Fatma Al-Awadi,

fields

of

water

treatment.

ACKNOWLEDGEMENTS

Resources thank

Development

Mr.

Sadek

Centre,

Bou-Hamad,

Power and Distillation

Plants,

wishes to thank all personnel

for her encouragement. Chief

Engineer

for reviewing of the Ministry

present who have made this work possible, by providing

technical

information

for

Deputy Director The author wishes Operation

this paper.

and especially

also to

& Maintenance

Finally,

of Electricity

of Water

of

the author

& Water,

past and

those who have helped

or helped in the preparation

of this work.

54 REFERENCES 11 Ministry of Electricity & Water Statistical Year Book, "Electrical Energy & Water", Kuwait, 1986. 2) Reside J, Ed. "The Government Of Kuwait's Sea Water Desalination Plants - A Report On 20 Years Experience", WROC R/18, 1973. Between Electrical Power & A.G.A. Fakhoury, "Inter-Connection 3) Abu Eid Z.H. First Arabian Energy Conference Generation & Distillate Water Production", Abu-Dhabi, United Arab Emirates, 1979. "Water Production Experience of the City of Kuwait", M.H., 4) El-Saie Proceeding Of The First International Symposium On Water Desalination, Vo1.3, 287, 1965. "History & Economics Of Water Production In Kuwait", Inter5) El-Saie M.H., Regional Seminar On The Economic Application Of Water Desalination, United Nations, New York, 22 September - 2 October, 1965. 6) Douvry R., & H. .Hauf, "Desalination Plants Of Total Capacity Of 112500 m'/day In Kuwait", 3rd International Symposium On Fresh Water From The Sea, Vol.1, 81, 1970. "5.0 MIGPD Sea Water Desalination Plants For The Ministry of 7) Harashina H., Electricity & Water, Kuwait", Desalination, Vo1.22, 425, 1977. & A.G. Fakhoury, "Some Special Design Features Of Kuwait MSF 81 Abu-Eid Z.M., Plants", Desalination, Vo1.23, 263, 1977. 91 Operating & Maintenance Manual For Shuwaikh Distillation Plants, Units Nos. Dl,D2, & 03, Contract No. MEW/C/P/760-77/78, Ministry of Electricity & Water, Kuwait, 1982. 10)Operating & Maintenance Instruction Manual For Ooha West Distillation Plants, Stage I (4x6 MIGPD) Units, Contract No.C/P/932-79/80, Ministry Of Electricity & Water, Kuwait, 1985. 11)Resini I., G. Coliva, A. De Maio, & R. Lucenti, "4x6 MIGPD Plus 1x1 MIGPD Desalination, Vol. 54, 377, (Acid) Plants - Two Years' Operation Results", 1985. 12)Zannoni R., A. De Maio, G. Odone & G. Coliva, "Prototype Test Results For Ooha West (Kuwait) 4x6.0 MIGPD Desalination Plants - Report On The Main Design Data Of The Above Plants," Desalination, Vo1.45, 337, 1983. 13)Operating & Maintenance Instruction Manual For Ooha East Acid Treatment Distillation Plant, Unit No.A8, Contract No.C/P/932-79/80, Ministry Of Electricity & Water, Kuwait, 1985. 14)Zannoni R., et al, "Desulphation New Applications: Doha East (Kuwait) & Gela (Italy) Desalination Plants", Desalination, Vo1.47, 93, 1983. 15)Operation & Maintenance Manual For Doha West Distillation Plants, Stage II Contract No.MEW/C/WDP/1086-80/81, (12x6/7.2 MIGPD) Units, Ministry of Electricity & Water, Kuwait, 1985. 16)Tender Specifications No.MEW/ZSDP/D8, Supply & Erection Of Al-Zour South Distillation Plants, Stage I, Ministry Of Electricity & Water, Kuwait, 1984. 17)El-Saie M.H.A., "Secret Of Success Using Hagevap (Poly-Phosphate) Treatment & Deaeration Of Sea Water Feed In Flash Distillation Plant", 3rd International Symposium On Fresh Water From The Sea, Vol.1, 405, 1970. 18)Al-Adsani A.M.S. "Kuwait's Experience Of Sea Water Desalination", A Paper Presented At The Meeting On "Water Desalination For Economic Development & Economics ", held in Egypt, 1975. 19)Khalaf K.A. & B.M. Watson, "Recent Developments In Elevated Temperature Scale Control", 3rd International Symposium On Fresh Water From The Sea, Vol.1, 524, 1970. EOIKalantar M.A., "An Evaluation Of Cyanamer P-35 Antiprecipitant For The Control Of Alkaline Scale In Low Temperature Sea Water Evaporators", WRDC/R/32, 1976.

55 "An Evaluation Of Belgard EVN Anti-Precipitant For The PllKalantar M.A., Control Of Alkaline Scale In Low Temperature Sea Water Evaporators", WRDC/R/, 1977. Scale 22)Butt F.H., & A.H. Bou-Hassan, "Performance Of A Polyphosphate-Based Control Additive In An MSF Plant Of Kuwait", Desalination, Vo1.36, 129, 1981. 23)Butt F.H., & N.G. Younan, "A Short-Term Low Temperature Test Of Belgard EVN Scale Control Additive In The Shuwaikh Fl MSF Plant Of Kuwait", WRDC/R/46, 1980. 24)Butt F.H., & B.Tanios, "High Temperature Operation Of Shuwaikh Fl MSF Plant Using Belgard EVN As The Scale Control Additive", WRDC/R/47, 1981. 25)"Performance & Cost Comparative Study On Two MSF Units Using Belgard EVN And Polyphosphate Carried Out At Doha East Power & Water Production Station - Kuwait", WRDC/R/52, 1984. 26)Watson B.M., "Operation and Design Analysis Of Acid Treatment & Decarbonation", WRDC Report No.8210/1, 1969. 271Burley M.J., & A.S.M. Hassan, "The Performance & Costs Of Solar Distillation In Kuwait", WRDC/R/Z, 1970. "Final Report On The 0.2 MIGPD Ionics 28)Reside J., & A. Al-Adsani, Electrodialysis Desalination Plant", WRDC/R/27, 1975. 29)"Proposed Guide Specifications For Mechanical Vapour Compression Distiller - 0.1 MIGPD Plant", WRDC/M/34, 1976. 30)"Recornmendations For Installation Of Alternative Method Of Desalination In Kuwait", WRDC/M/32, 1975. 31)"Comments On Reverse Osmosis Water Treatment Plant For Brackish Water", WRDC/R/29, 1975. 32)Elliot M.N., J.Reside, A.Abou-Hassan, & A.S.M. Hassan, "Operation Of The Gulf Environmental Svstems 4.000 GPD Reverse Osmosis Unit", WRDC/R/5, 1972. 33)Al-Adsani A.M.S., A-.Bou-Has&, & A.L.A. Malek, "Testing Of Three Different Types Of Reverse Osmosis Membranes At Water Resources Development Centre", Desalination, Vo1.22, 271, 1977. "Speech Delivered At The First Desalination Congress Of The 34)Abu-Eid Z.M., Americas Held At Mexico In October 1976, WRDC /P/7, 1976. 35)Kaschemekat J., et.al., "Two-Stage Reverse Osmosis Sea Water Desalination", Desalination, Vo1.46, 151, 1983.