Experiments on RO process for production of boiler make-up water from sea water

Desalination, 56 (1985) 3 6 7 - - 3 7 9

367

Elsevier Science Publishers B.V., Amsterdam

Experiments

-

Printed in The Netherlands

-

on R O Process

for P r o d u c t i o n

Boiler M a k e - u p W a t e r

of

from Sea Water

K. Ohta I), H. K a n e d a I) M. Hirai I), K. K i k u c h i I), Y. M u r a y a m a I) S. Yamada 2) , N. Sato 2) , S. Masumi 3) and E. N i s h i y a m a 4)

Abstract In J a p a n , water

a power

resources,

make-up

water.

demerits

such

start

up and

adopt

through

as

1984

scale

in S a k a i d e

station.

directly Power

And also,

been clarified.

economy

the Toray's

of cost

on

for p r o d u c i n g

complicated

difficult

osmosis

(RO)

process

in

boiler but has

operation

for

sea

water

had been

carried

that

both

the single

stage

to the p r o d u c t i o n systems

spiral

estimation

of

production

out

of b o i l e r

from

1981

and the double

make-up

and their o p e r a t i n g

wound

showed

are n e a r l y equal and r e l a t i v e

are

process

w a t e r of good quality,

consumption,

reverse

from

the o p t i m u m

modules

results

energy

showed

are a p p l i c a b l e

using

The

produces

in a a r e a p o o r

Station.

results

each process

processes

at s e a s i d e

distillation

process

much

experiments

water

experimental

have

water

located

prevention.

the

stage RO p r o c e s s e s power

sea

corrosion,

make-up

The

the

is w h i c h

The d i s t i l l a t i o n

Therefore, of b o i l e r

station

modules

or T o y o b o ' s

that the p r o d u c t

merits

water

water

in a

conditions hollow

of

fiber

costs of both

of the t w o p r o c e s s e s

in t e r m s

of

to define.

i. I n t r o d u c t i o n water

desalination

several

Sea

years

and

various

places

the Water boiler place

large

by RO p r o c e s s

scale

of the world.

Re-Use

make-up

Promotion

water

of d i s t i l l a t i o n

of

made

commercial

The e x p e r i m e n t s Center

good

RO

plants

progress

have

been

for the last installed

had been c a r r i e d out since

to d e v e l o p

quality

remarkable

directly

a new from

technology

sea

water

in

1981 by

of p r o d u c i n g

by RO p r o c e s s

in

process.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Note:

i) W a t e r R e - U s e 3) C h u g o k u

Promotion

Electric

Center

Power Co.,

Inc.

2) S h i k o k u 4) K y u s h u

Electric Electric

Power Co., Power Co.,

Inc. Ind.

368 An e x p e r i m e n t a l p l a n t was c o m p l e t e d in S a k a i d e P o w e r S t a t i o n of S h i k o k u Electric Power Co., Inc. in March 1982, and the experiments using the test plant were carried out from April 1982 through March

1984.

The cumulative

operating

hours reached to I0,000 hours.

2. Description of the Test Plant The process consists of a pretreatment RO system using spiral wound type modules type modules)

system,

and an RO system

and an ion exchange demineralizing

and a mix bed type).

two kinds of RO system

system

using hollow

(a 2-bed 3-tower

Flow diagram of this process is shown in Fig. i.

2.1 Pretreatment System In-line coagulation, dual media filter and polishing filter Capacity: 200 m3/day

2.2 Spiral Wound Type RO System Single stage and double stage processes Capacity:

Ist stage 25 m3/day 2nd stage 20 m3/day

RO module: Toray ROMEMBRA

(PEC-1000)

ist stage:

SP-120 x 1 (~8 in., 6 elements/module)

2nd stage:

SP-IIO x 1 (~4 in., 6 elements/module)

2.3 Hollow Fiber Type RO System Single stage and double stage processes Capacity:

ist stage 20 m3/day 2nd stage 15 m3/day

RO module: Toyobo HOLLOSEP ist stage:

HM8255FI x 1 (~8 in., 2 elements/module)

2nd stage:

HR5355FI x 2 (~5 in., 2 elements/module)

2.4 Ion Exchange Demineralizing System 2-bed 3-tower type and mix bed type ion exchange processes Capacity:

2-bed 3-tower type 25 m3/day mix bed type

25 m3/day

(an

fiber type

369

Ion e x c h a n g e resin: U M B E R L I T E Cation resin IR-120B A n i o n resin

IRA-410

~,HSO~

Ro~le

(11

(21 131 (41

~

R O - ;~

(I;)

(IB)

R O -. 2 . ,

{zo)

Ko-2a

(zl)

(zz) (z3)

(z41

Fig. I : Flow Diagram of Test Plant

(1) (2)

Sea Water Tank Pressurized Dual Media Filter

(3) (4} (5) (6) (7) (8)

Pressurized Polishing F i l t e r Pretreated Water Catalystic resin deoxidizer RO-I Feed Water Tank BackwashableSafety F i l t e r Cartridge F i l t e r

(9) (lO) (ll) (12)

SW 1st Stage RO Module 1st Stage Permeate Tank SW 2nd Stage RO Module Decarbonator

(13) 2-Bed 3-Tower Type Ion Exchanger (14) (15) (16) (17) (18) (19) (20) (21) (22)

Product Water Tank Mix Bed Type Ion Exchanger Pure Water Tank RO-2 Feed Water Tank Backwashable Safety F i l t e r Cartridge F i l t e r HF Ist Stage RO Module Ist Stage Permeate Tank HF 2rid Stage RO Module

(23) Activated Carbon Tower (24) Decarbonator

06)

370

3. E x p e r i m e n t a l

Results

3.1 P r e t r e a t m e n t Raw

sea

condenser

of

water

The change index

of r a w

pressure

of t h e s e

power

of p r e t r e a t m e n t

sea

water),

d r o p of d u a l

SDI

experiments

SDII5

media

performance,

discharged

temperature,

(silt d e n s i t y

filter

are

t I = Time

taken

t 2 = Time

taken to filter

tf = T i m e This

to f i l t e r

sea

water

from

index

shown

of

in Fig.

SDI 1 (silt density

pretreated

sea

water)

and

2.

of c o n t i n u o u s value

(SDI I) of

is

raw

In the e x p e r i m e n t s 80 i n s p r i n g

It

is

polishing

effective filter

kept for

after

stabilizing media

water

after

tf m i n u i t e s

~

15 m i n u t e s

water,

but

for

measurement

it is t a k e n

1 minute

of

SDI

for

SDI

SDI 1 of the r a w and

winter.

4, m o s t l y SDI

less

of

the

Run -- ~ l

sea water

While, than

changed

from

of the

pre-

SDII5

3, the t a r g e t

pretreated

water

value. to

add

a

filter.

Run -- 6 i

water

water.

less than

a dual

Run -- s r

sea

taken sea

t o 40 i n a u t u m n

were

500 m l of t e s t i n g

filtration

usually

on p r e t r e a t m e n t s ,

and summer

sea w a t e r

the f i r s t

500 m l of t e s t i n g

filtration

(SDII5) of p r e t r e a t e d

o

the

= (i - t l / t 2 ) / t f x i00

continuous

treated

was

station.

r

~n-S I

l

-

-

I

i

Run-~

i

~

Run - 1 o

i

i0

20 o ~

2o

Guide Line for RO Feed Mater _ ( Target Level ) i E

Hay

April 19a3 Fig.

2:

June

July

August

£]apsed Change o f Sea Water Q u a ] | t y

September and Performance

October

November

DeceiVer

Change o f P r e t r e a t m e n t

Equipment

January 19~4

February

371

3.2 RO S y s t e m Experiments one year through

on

in 1 9 8 3

the

1984. The c u m u l a t i v e

(I) Spiral The

wound

The

fiber

Ist

Chemical

3.2.1 The

Stage

Quality test

10,404

pressure

(i) Spiral

Wound

Electric

RO

of

the

water

test

RO

the

2nd stage

a n d the

membrane

condition

about

from

1983

was

not

throughout

the

8,433 hours.

necessary

from

the

ist stage

was

stable

and g o o d d u r i n g

test

the

quality

for the

ist

stage ratio

RO process

was

s e t as t h e

40%.

Type M o d u l e

(m value)

of p e r m e a t e

was

nearly

run No.10,

quality.

i n s t e a d of s o d i u m

approximate

operating

conditions

sulfite

results, can

be

was

achieved

permeate

made

~S/cm and p e r m e a t e

230

to i m p r o v e

of p e r m e a t e

7, a catalystic

(SBS) dosing it

10% r e d u c t i o n for

was

good quality

approximately

hydrogen

of p e r m e a t e

was approximately

zero.

the e x p e r i m e n t

For getting

experimental

However,

to

150

for r e m o v a l

~S/cm

of p r o d u c t i v i t y

quality,

because

the p r o c e s s

by k e e p i n g

deoxidizing

ascertained as

the

in

conductivity.

was observed value

pH

oxygen.

improvement

electric

of pH

high

resin w a s u s e d

of d i s s o l v e d

that

for

at t h e b e s t

change

of

feed

water. The change of the ist stage RO p e r f o r m a n c e

in

during

5,678 hours.

2nd stage

55 k g / c m 2 and the r e c o v e r y

v a l u e of feed sea w a t e r

sea

out

continued

Process

conductivity

flux d e c l i n e

From

carried were

t i m e s w e r e as follows:

and

hours

of the the p e r m e a t e

standard

operating

good

were

RO process

period.

The

At

operating

9,784 hours

cleaning period.

R O process

stage

type

stage

experimental ist

stage

type

ist stage

(2) H o l l o w

the

single

and on the double

Fig.

(2) H o l l o w

Fiber Type M o d u l e

Electric was about type

for spiral w o u n d m o d u l e is s h o w n

3.

conductivity

0.015.

module

of p e r m e a t e

The change

is s h o w n

in Fig.

was

approximately

of the Ist stage 4.

200

RO performance

~S/cm

and m value

for hollow

fiber

372 -- Run-$

,r-.

Run-a

~'I~

Run-/

~;=

Run-S

50o I~ Experiments for Permeate Quality I~rovement

400

300 RO0

m .g

"

i

I

• a

I

g

° I

l

I ~

.

.

.

.

.

.

~I

ws

I

..

zoo I

I

6,000

I

?.OOO

I

B,OQO

9,000

|O,O00

Recovery Ratio: 40% Operating Pressue; 55 kg/cl~ Feed Hater: Sea Hater

a

" . . . . . .

4~ J

%

I

I

w

• '''...,,o

os I

I

S.O00

I

?.000

I

e,O00

,

9.000

10.000

Elapsed Time (h) Ftg. 3: Performance Change of the 1st Stage S p i r a l Wound PIodule

Run-6

:~

400

~

3oo

~ '

I

e

.

.

~:

.

.

.

.

Ru~?

o

~

I

I

I

"

~',~

.

Ru~ll

" l ~ . m ' .

.

.

.

.

.

~=

.

Run-e

~

Ru~10

)1

.

,oo ~'

o|

•

/ ].sl

I

I

I

I

Recovery R a t i o : 402; Ot0eratlng Pressue: 55 kg/cm2 Feed Water: Sea 14¢ter

}.il..........

D

I

?

I 7000

°

.

i

•

.

.

.

,

.

..

I (~000

~*

a

•

o

Q $

I

o

wi

.p

t

I*

.

.

*

.

I 9000

Elapsed Time {h) F i g . 4: Performance Change of the 1s t Stage Hollow F i b e r Module

..,,

i

IHee

,',

373 3.2.2 The 2nd Stage RO Process For the purpose of i n v e s t i g a t i n g the 2nd stage RO process, operating

the experiments

suitable

were

operating

carried

conditions

out u n d e r

the

of the

following

conditions:

Module

Operating pressure (kg/cm 2)

R e c o v e r y ratio (%)

pH

Spiral W o u n d

25 ~ 40

80 % 90

"3 ~ 8

H o l l o w Fiber

20 ~ 30

80 % 90

3 ~ 8

Based on the e x p e r i m e n t a l results, the o p t i m u m o p e r a t i n g conditions for the 2nd

stage

RO process

was

established,

and the

2nd stage

permeate

of e q u a l

q u a l i t y w i t h the p r o d u c t w a t e r by d i s t i l l a t i o n process was o b t a i n e d stably. (i) Spiral W o u n d Type M o d u l e Quality

of t h e p e r m e a t e

under the o p t i m u m

was about

2 ~S/cm

o p e r a t i n g conditions.

For the purpose stop SBS dosing

f r o m t h e 2 n d s t a g e RO p r o c e s s

of i m p r o v i n g

or to d o s e s o d i u m

the permeate sulfite

quality,

instead

it w a s c a r r i e d o u t t o

of S B S f o r k e e p i n g

h i g h pH

value of the 2nd stage feed water. The change

of p e r m e a t e

and q u a l i t y of feed w a t e r

quality during the experiments

(Ist stage permeate)

and p e r m e a t e

is s h o w n from

in Fig. 5

the 2nd stage

RO process on the o p t i m u m o p e r a t i n g conditions are s h o w n in Table i.

(2) H o l l o w Fiber Type M o d u l e For carried

the purpose

of i m p r o v i n g

d e c a r b o n a t i o n in the process. permeate

the permeate

out to find out the optimum

from

the

quality,

operating

the experiments

conditions

and

the

A c c o r d i n g to the e x p e r i m e n t a l results,

2nd stage m o d u l e

was

ascertained

2 ~S/cm

under

were

point

of

q u a l i t y of

the

optimum

o p e r a t i n g conditions. The change

of p e r m e a t e

quality during the experiments

and q u a l i t y of feeds w a t e r (Ist stage permeate)

and p e r m e a t e

is s h o w n

in Fig. 6

f r o m the 2nd stage

RO p r o c e s s o n the o p t i m u m o p e r a t i n g conditions are s h o w n in T a b l e i.

374 Table

i: R e s u l t s

of W a t e r

Type Item

Quality

Spiral !Unit

Electric Conductivity

pS/cm

TDS

mg/l

Feed Water

Brine

138

1540

Analysis

for the 2nd Stage

Wound

Permeate H o l l o w Fiber

Permeate

Rejection Rate

2.66

99.68

195.5 109.5

Feed Water

Brine

Permeate

Rejection Rate

2000

2.60

99.77

1092

1.5

99.75

80

930

4

99.70

C1

32.9

351

0.4

99.79

56

604

0.5

99.85

Na

26

296

0.5

99.69

30

325

0.31

99.83

Mg

0.66

6.07

<0.02

>99.29

K

0.7

7.1

<0.I

>97.44

1.8

20

<0.2

>99.82

3.2

26.2

SO 4

13.8

208

B

0.6

5.2

F

0.008

0.038

<0.005

SiO 2

0.002

0.009

<0.002

IOC Note:

23

0.I

142

96.55 >78.26

12

85.45

.... ~

9.2

1.2

78.38

0.027

0.005

70.59

0.003

0.006

0.003

<4

<4

r ....... -I

>, ..

Note:

., .-

Recovery Ratio: BO - 901 Operatin9 Pressure: 3Q - 40 kg/cm2 $BS: Sodlcln Hydrogen Su|flte

-"

. " . ." ....

,

r Elapsed Time ( h ) F i g . 5: Permeate Q u a l i t y

97.96

1.9

Experiments f o r Permeate Q u a l i t y Improvement

&

99.08

0.3

0.007

O p e r a t i n g Pressure: 30 k g / c m 2 Recovery Ratio : 90% N u m b e r of T e s t : 2 IOC : Inorganic Carbon Feed w a t e r is the p e r m e a t e from the ist stage RO.

....

<0.i

Change o f t h e 2rid Stage S p i r a l

Wound Module

<4

-

375

Run-S

•

~

~l' Run-e I

Run-7

I,

R.....

I

R.....

Exper|ments for Permeate Quality Improvement

~1 >1

Note: Reovery Ratio: 80 - 90Z Operating Pressure: Z5 - 30 kg/cm2

,oo

,°o

sooo

Elasped Tim (h)

Fig. 6: Permeate quality Change of the 2nd Stage Hollow FJber Module

4. C o n c e p t u a l Design of C o m m e r c i a l

Plant

4.1 General P l a n n i n g C o n d i t i o n s General p l a n n i n g c o n d i t i o n s are as follows: (i) The d e s a l i n a t i o n plant shall be located in the site of p o w e r station. (2) Product w a t e r shall be used for m a k e - u p w a t e r of s t e a m generator. (3) Plant

capacity shall be 2,000 m3/day.

(4) Unit c a p a c i t y shall be 1,000 m 3 / d a y and unit n u m b e r (5) Sea w a t e r

intake and brine discharge

be p u t to c o n c u r r e n t

use,

except

shall be 2.

facilities of p o w e r

for n e w l y

installed

station shall sea

water

and

drainage w a t e r d i s c h a r g e conduit and p u m p s n e w l y installed. (6) The plant shall be o p e r a t e d under full a u t o m a t i c

system.

(7) R e q u i r e d e l e c t r i c p o w e r shall be supplied d i r e c t l y f r o m p o w e r station. (8) One unit of standby facilities shall be p r o v i d e d per rotary a p p r a t u s such as pumps,

two

units of m a i n

b l o w e r s and m o t o r s in need of continuous

operations. (9) Scope of conceptual d e s i g n shall include f a b r i c a t i o n and i n s t a l l a t i o n of sea water system,

supply and brine discharge

ion exchange demineralizer,

system,

pretreatment

system,

RO

w a t e r storage tanks and b a c k w a s h i n g

s y s t e m and civil e n g i n e e r i n g and c o n s t r u c t i o n works.

376 4.2

Conceptual

4.2.1

Cases

Design

of

Conceptual

Conceptual of

these

cases

Case

I:

as

Double Dual

2:

stage

media

Single

The process

target are

media

values in

prepared

for

the

two

cases

and

schematic

flow

RO process ~

RO ÷

Polishing Mix

bed

filter

ion

+

The

ist

stage

RO ÷

exchanger

RO process

filter

3-tower

Treated

shown

be

filter

stage stage

2-bed of

shall

follows.

2nd

Dual

4.2.2 Q u a l i t y

Design

design are

The Case

Conditions

ion

+

Polishing

exchanger

+

filter Mix

÷

bed

RO + ion exchanger

Water and

Table

guaranteed

values

of

treated

water

quality

for

each

2.

Table 2: Treated Water Quality for RO Facility and Ion Exchange Resin Facility Electric Conductivity (~S/cm) Case Process Guaranteed Value Target Value

1

2

RO-I

<700

<300

RO-2

<30


MBP


RO-I

<700

<300

2B3T


<5

MBP Note: RO-I RO-2 2B3T MBP

4.3 R e s u l t s

of

Cost

4.3.1 C o n s t r u c t i o n Results 4.3.2

Product Table

water

cost.

of

<0.i

<0.i


= = = =

ist Stage RO 2nd Stage RO 2-Bed 3-Tower Ion Exchanger Mix Bed Ion Exchanger

Estimation

Cost construction

Water

4 shows

cost

estimatation

are

shown

in T a b l e

3.

Cost the

results

of

cost

estimation

on a n n u a l

expenses

and

product

377 Construction estimated

cost

on the

Operating Price

following

time

price.

per

of e l e c t r i c

Replacement Fig.

7 The

and

the

boiler

make-up

water

were

330 days 6 US Cent

RO module

relations water

than

that

of

electric

power

price

is

less

slightly

higher

that

p e r year:

between

cost

lower

than

for

conditions:

slightly

US

cost

year:

of

product

water

power:

rate

shows

product

of

the than

of C a s e

product

the

double

single 3 US

2 when

stage

water stage RO

Cent/kWh,

the

per

kWh

25%

electric

cost RO

and

process

process but

electric

the

power

cost

price

Cent/kWh.

Table 3: Summary of Construction Cost [US$1,000]

Item Sea Water Intake and Brine Discharge Main Facility Electric Power Supply Facility Civil Works and Building Reservoir Total

(Case

(Case

Case 1 Case 2 Double Stage Single Stage 128

128

3,592

3,368

112

88

1,192

1,120

296

296

5,320

5,000

Note: Main facility includes pretreatment, waste water treatment, RO equipment, RO element and demineralizer.

2) of

is

power i)

when Case

more

was the 1 is

than

3

378 Table 4: Summary of Product Water Cost Case

Case i: Double Stage Process

Case 2: Single Stage Process

Item

Annual Product Annual Product Amount Water Percentage Amount Water Percentage [US$1,000] Cost [%] [US$1,000] Cost [%) [US$] [US$]

Capital Cost [Depreciation & Interest]

606

0.92

45

584

0.89

45

Operation & Maintenance Cost

731

I.ii

55

709

1.07

55

Energy

389

0.59

[29]

309

0.47

[24]

Replacement of Membrane & Resin

177

0.27

[13]

134

0.20

[i0]

Expendables [Chemicals, etc.]

104

0.16

[8]

208

0.31

[16]

61

0.09

[5}

58

O.O9

[5]

1,337

2.03

1,293

1.96

Contingencies Total

i00

Note: Plant capacity: 1,000 m3/day x 2 units Operating time: 330 days/year Electric power price: 6 US Cent/kwh Rate of membrane replacement: 25%

2,5

Estimate Condition: Plant Capacity: 1.000 m3/day x 2 Units Annual Operating Time: 330 days /

A"

,=

7i

2.o

-~ o 1.~ A: Case I - Double Stage RO Process (l~O + R0 * HBP) O: Case 2 - Single Stage RO Process (RO + 2B3T + /4BP)

1.0

I

I

I

i

I

0

2

3

4

5

6

Electric Fig.

i

7

8

Power Price (US Cent/kWh)

7: R e l a t i o n s

between Product Water Cost

end £ ] e c t r t c

Power P r i c e

10

i00

379 5. C o n c l u s i o n (i) Both the single the p r o d u c t i o n (2) P o l i s h i n g

filter

the p r e t r e a t e d (3) Double get

stage and the double

stage

equiped

process

process

ion e x c h a n g e (4) Single

system

is e f f e c t i v e

to s t a b i l i z e

SDI value. is a

stable

process

even

of the ist stage RO trouble.

to p r e v e n t

RO p r o c e s s

ion e x c h a n g e

(5) P r o d u c t i o n double

to

from

an sudden

the

feed

And then,

load increase

water

quality

this p r o c e s s

is

on the f o l l o w i n g

demineralizer.

stage

existing

are a p p l i c a b l e

from sea water.

in p r e t r e a t m e n t

sea w a t e r RO

worse because

helpful

stage RO p r o c e s s e s

of boiler m a k e - u p water

cost

stage

system

for boiler

RO process

the r e l a t i v e

is easily

merits

are

applicable

to c o m b i n e

for p r o d u c t i o n

of boiler

make-up

of b o t h

nearly

of these

process

water equal

two processes

and

make-up

with

the

water.

the single

it is d i f f i c u l t

stage

and

to d i s c u s s

in t e r m s of economy.

Acknowledgement

The experiments Chugoku

Electric

Electric JGC

Power

in

Kimura

Kobe

Laboratory of

University

University for

carried

Inc.,

Kyushu

Ltd.,

Toray

Industries,

their

to for of

instructive

Dr.

Industry

the helpful Power

including

Water

Industries,

to these

former

(NCL), and

Prof.

Dr.

advice

and suggestion.

Shikoku Co., Ltd.,

Ltd.,

Sasakura

Co., Ltd..

Director

H. O h y a

Inc.,

of

Organo

companies

for a s s i s t a n c e

General

Dr. H. Y o s h i t o m e

Tokyo

cooperation

Co.,

Japan

Inc. a n d T o y o b o

thanks

Kato,

with

Electric

Kurita

sincere J.

out

companies

Steel

extend

particulalr,

Chemical

Co.,

Co., Ltd.,

The a u t h o r s and,

Power

been

Co., Inc. a n d o t h e r

Corporation,

Engineering

have

of

of NCL,

of

National

Prof.

Yokohama

Dr. S.

National