Corrosion under heat flux encountered in desalination plant

Dewlinction,22(1977)369-378 8IzIsmriersciell~Puhlistziag~rrrpmy.

S.

and Dr_ T_ SHINOHAR4**

KID@

co-q

Toyo Engineering

o;?crational nation

plant

continuity

be the first

ment

attack

plant

preheater tinuing

Film

Flush

cause

of these

no product

as to give

for cleansing

which

plant

piant:

Fine

*

1

transfer

,

suspended

1s expected,

-

to heat

and impinge-

In HultxpLe

contamination

access

naterrzls

sands

aftacks,

and pl.ugging

of dxtillatlon

are reqrured

to treat

to say, a comblnatron

Needless

essentially coqlicate

conceals

and difficult

of organrzationsllr2) introduce

new configuration Besides,

severely

tubes

at any tuze while

-‘,

in

con-

proof

to plant

of ineqericnccd

a

neasur-it-q tcchn~c_ue on liquid

Present

*+ prese&

address: address:

problems

liquids

still

retain

rn a Y%iF plant,

ado$=ed

CoIroSivity tine

sea water. surface

and development

problems

experienced

be helpful

corrosive

of heat ex-

r+es

which it note

materials,

in research

the corrosion

a few cases

consists

and heating

of corrosion

to select

efforts

of corrosion

it wzll

type nainly

of sea water

a possibilxty

For all extensive

l

of pl.znt

rn desali-

operation.

changers,

real

probla

disctlss inlet attack

Strge

(MZFF) process,

and condenser

Dcsalinat*on

Authors

corrosion

a an

is so designed

is the t~)st ivrtant

Authors

rn a Multi

are considered

Falling

and MIX?

and stability

to be solved.

eqerlenced

in sea water

(Japan)

and for this purpose

must

Effect

Tokyo

L

in

.=FF

designers

done by .= nuplxer unsolved. then discuss

plant.

to be aware of the

Authors have developed '.l . corrosivity under the same ,_

in cdvanco,

Corp., Higashi Rlarketing Div,, Toyo Engineering Exxnabasfi. Funabasti, technical Laboratory. Toyo Engineettig Corp., ?bbXd,Chtid

a

condrtrons

of lquid

applyrug

a.ud heat

velocity

the principle

Inlet attack

and impingesuzmt attack

of Cu-alloy

Host of tzhe HSF plants aperating oE heat

exchanger Damages

likely close

heat

at present

such as Al-brass,

on the tube wall veq

cup=_ -nickel, etc. attack

in opera&g

plants

by

method-

PUWT

INAMSPIESALSHATIC@J

amRDsIoNsRco-

material

flwc cs those

of a linear polarization

adopt

90-10

to occur

erchanger Cu-alloy

cupro

for tube

nickel,

on these materials

to the tube inlet and

70-30

are inlet

impingemt

attack

on the tube sheet, In a HSF plant iuletattackwas

secticln arrd the 90-10 The impingement the up-stream of these

tub= type o-rated for hut one year, the the Al-brass tubes in the heat recovery

of CLOGS

discoveredon cupro

attack side

attacks

nickel

lz& developed

betueen

On the other exchangers

Section,

recovery

hand,

sectian.

Tests

mre sands

severely attack

of the highest

Dezincification

data

as stated

silica

show

the state

in its

the part

of the

corroded. uas observed temperature

was also observed

in all the in the heat

on the swface

of

tube sheets.

and inspections

Design

conducted

tube sheets at

brass

and Fig.-2

dpttack was observed

the inlet

the iqingemnt the wt

of tubes and tube sheets, water.

Fig.-1

4O'C and 9O*C , eqecially

45OC and 60aC were

except

the naval brass

on the naval

section,

rejection

in question-

In the heat recovery

heat

in the heat

in the both sections.

part of the tezzperataue between kqeratuze

tcbes

in various the scale

and operating above

suqended

records

revealed

than in other plants in the se2 water

methods

~II the

that

were given

corroded Were

in this plant

in Table-l.

axe considered

and the sea

also analyzed.

the scale

as shown

to the material

mterials

The work contained

Consequently,

the main

cause

fine

of these

att&zJca, Crevice

corrosion

Titauium against

hardly

is well

sea water. been

Although

of titanfun knmrn

heat excltsnger as the meti

of an excellent

arrticorrosi~ness

Ike ~ane~nomlcalrea~,hc~v~,tt-tan~mrhas

used fordesalinationplantthis

andall

structural

crevice

corrosion

metal

is widely

par&

in&??Fplaht,

and hydrcqen

regarded

attack,

there

as better

material

still Eemakr

for every

problemsim

Following

plant

in a HSF

is an e%msle of cross

The crevice plant

which

the brine

heater.

Fig.-3

between

titani=

of

t&s

corrosion

after

fo r all the tubes

shows

of titaniln

cza

wall

grown

4 conth

emerienced

operation

and the tube

the state of the corrosion

the roll-expanded

0.5

conpound

was discovered

titznium

at the crevice

corrosion

tube type.

corrosion

adopted

of crevice

tubes

thicknens

in the crevice,

which

except

occurred

and the tube sheets.

damaged

were

of the

sheets

which

and deformed

finally

intruded

The

by the into soxe

of the tubes. The corrosion and

11OT,

corrosion

occurs.

bekeen

In this

Fig.4

case,

shows

the outside COXROSXQN

where

desrgned keeping

as

&fSF

plant

condensing

the vapor

The preheater is separated

of

the heat

tqerature

stage

a plant

to be dcne

layer on

the parts

should

of

be so

for any damaged

parts

plant.

surfaces

in Fig.-6.

bemg

and the tube side

except

The

tube sheets

t.zainly The

heated

shell

uhlch

side

are

is one room with

the one at the top where-the

system.

the same as the preheater

are provided-

vater

sea

plant

In Fig.-5.

of the tubes.

as shorn

in the entire

EZFF~)

improved

in a form of thin film, whrle

by the interstage

water

further

as shovn

type, where

tubes

heat duty,

is made

dioxrde

is to niniruze

secondary

desalination

a vertical

sea

is the lowest

tube sheetz

effect

roozs

in

was also observed

is the one that has been

has one nest only

dipped

The condenser

and

remedies

transfer

res_pectively of different no tube sheets

prevention

on the outside

in several

titani-

to be

hydrid

and the titaniun

eva_porator and condenser

are cl1

inside

analyzed

operation.

here

multiple

of preheater,

heat exchangers fall do-m

stable

discussed

from a convensional consists

mediate

under

condition

re_porteda).

PEtfXESS

to corrode,

to enable

8WC

the

tubes.

for corrosion

liable

a plant

.SZEf

was

between

the severer

on corrosive

already

of titanic

metal

of corroded

step

are

the data

ccazpound

betveell the base

PFtEViZNTXON IN

rrses,

the cozqarlson and

type, and growing

surfaces

first

The

plant

of the temperature

the tqrature

the corrosion

of tuthile

at the boundary

at the part

is the hlqher

the daka of thx

dioxide

plant

was observed

and that

except

for no inter-

372 Table-2

shavs

The configuration bemeen

the specification

E!EFF andHSFpla.ntdlle

configuration the points (1)

of heat

of heat exchangers

distinguishes

4s stated

exchangers

in HEFF plant.

and the flow pattern

compared KZFF plant

from other

of sea water _ of this

!Ehe adaption

inTable-3.

conventional

plants

on

below.

HO acmulation

of sludge

and slime

is expected

on the heating

SWfZCe.

(2)

The

uater

boxes

elininate a gentle

requires

direct

contact

shell and tube heat point

under

(51 It realizes tubes ever

heating

arising

in sea water a

at

the

fear of the

system,

BSFF plant

requires

above

no

the boiling

operation

and condenser

to give

access

for cleansing

tc heat

transfer

and plugging

technique

on oorrcdon

when-

measutkg

tube has not been popularized,

because

under

the condition

of heat

and the slope

vh~h

is unsuitable

for the test apparatus.

have developed

tecnique

the ccrrosion

transfer

trarsfer

test Eethcd

for the use in a laboratory

corrrusion rate of heat

adopting

research

tubes

of the

the electm-

and also

in an actual

of

for zmi-

plant.

rate measurement

Authors

measured

the ccrrosion

tiich

vas divided

respectively

as shobn

in Fg,-7,

neterlng

apparent

politd~tion

the

to

pressure,

of a el&trochemic.zl

a heat exchanger,

pieces

dipped

and eliminates

exchange r for preheating

a continuous

transfer

the test specimzn

Corrosion

sheet

me,

the atmspheric

in preheater

Application

tcrrng

due

so required.

test of a heat

Authors

exchangers

on the tube sheets,

attzcks.

(4) Adopting

chemical

attack

no t&e

and high temperature

cedzua

phenomena

at the top of all heat

t=e

coverrent of sea water.

(3) The preheater

both

of pool

a fear of frcpingmt

of the speck,

qplying

rate of a test speck into

four pieces

The carrotion resistance

E relation

ratewas R bet%?en

betueen

installed

being

in

insulated

clete

F

ed by

the opposite

corrosio;r!rate

two

and

373 ~larfzation actu&

resistance

corrosion

previously

measured

rzte at the previous

loss of the other

two pieces

at the laboratory

test was cakulated

of the speciuen

tkn

those

the pola.rFzationresistance, and the proportional tion was obtained value

fmn

of l/R during

tronal

coefficient

Corrosian

on carbon

Fig.-8

apparatus, thk

surface

of heat

czthod, transfer

and Fig. -10 she-xs the actual

corrosion

process

plant

with better

is the one

2uthers

a data of the propor-

Ecasured

tube being Frg.-9 data

is the mst

and the selection of high

the ptobles~s to soxe extent desalination

shows

of the rela-

by the average

of

2 corrosion

contacted

shows

wrth

the system

corrosion

potentral

potensuch

of this -as-

apparatus.

In des2lination, considerad

for neasurmg

measurement

corrosive fluid as brine and sea veter. uredby

by the weight used

coefficient

rate divided

The

steel.

a back capillary

tial on inside

corrosion

the test period.

potential

Applying

the actual

test.

under

but not

stable

ixzpottant problems

the all.

and continuous

equipckent configurations.

that direst

come

close

to be well

grade nxtterials may possibly It is essential operetion To

our

solve

to mintain

by improving

belief,

a

MEFF plant

to the end.

1. OSW R K D FJept. No. 308, Ho. 417 2. Corrosion Eng'g 2 No.5 Cl9761 Bulletin 3,I~perialKet2lIx1d. Corp., Titaniun Information 4.' g.C. Standiford, Y, Ishikaua, 5th Xnt. Syzq. on Fresh Water Sea 2 (1976) 301

frun the

374 ccq~~unds of Sludge Ch&cal at E!eat-Recovery Section

Table-l

an Beat-Exchanger

B

C

26.2

21.8

30.0

SiO2

28.5

23.1

13,4

Fe203

6.5

14.3

23.1

CZO

0.4

13.2

0.9

nso

3.2

1.3

3.8

CLaNT

NFL!!

1m1Tx<3pI

Loss

A

CUO

17.9

so3

2.9

la.7

0.9

2.2

Ai

5.5

7.4

6.1

zno

0.3

5.1

0.3

-207

3.0

3-2

?&Cl

23.2 1.1

4.7

Ha0

Specification (Caperity

3

111.0

A plant daraged in the same as the present plant

C!:

A flavless

plant

106.4

of Heat Exchanger MIGDI

Prehecter

of exchanger

Vertical shell

Typeoftube Hateria1

B:

plant

2.0

99.2

ToTA3.l

Type

The present

0.1

NH4

Table-2

A:

2.3

ICC1

Tube

and tube

l-1/2" of tube

Tube bundle

srr>oth tube

of EEFF

Evaporator

Condexer

Vertical Shell and tube

Vertical Shell und tube

2" fluted

2" fluted

9Dcu - lOXI

Al-brass

2700

each

E&

Process

2000

tube

tube

9ocu - l(Fli mq$

2000

zzq#S

Tabl-3

Cmpariscm Equ&xzent

of LiqGd

Flaw Pattern

and

Configuration ~tveefs HEFF arrd ?SF

ox-ass

Esi? tube

type1

Evaporation

m

of exchanger

Flew pattern

Vertical

Falling

shell

and tube

film inside

Flush&x Violent

flushing

tuknz Water

box

Top water pool effect

at each

Preheating uaelow Type

Flow

100°C)

of

exchanger

pattern

Vertical one body

Falling

shell and tube, czal!struction film inside

tube

Horizontal

shell

tube, cross-tube Nl

l&quid

and

type

flovin

tube Water

box

Top water pa01 to atcmsphere

exposed

Sax type aud full Liquid at each stage

Preheating (over 1OOW Type

Plov

of exchanger

pattern

Direct contact heating of vapor and sea uater

Ebrizontal

shawer

Nl

tube,

shell

cross-t&x

1iCpid

and type

flow in

tube Waterbox

Type

of exchanger

Boxtypeand liqwid at

each

full

Eztrizontal

shell

tube, crass-tube Plow

pattern

Waterkox

Falling

filminsidetube

water pool to atmxphere

Top

exposed

Full. liquid tube

skqe

and

twe

flow in

fqpe and full lipuidateach stage

Box

376

Frg .-1

Trax’sVerse

Dmged

by

mq*- 2 Transverse Naval

I)aaged

Bzass

ticrosbUctt.Ce Inlet Attack

of

Xicrostrucltute

of

T&e

ti-Brass

Pig. -3 Crevice

Plate

by Iopingeuent

T&e

Attack

Corrosion

of

Titanium Heat Exchanger

377

Fig. -4 +erating

Danaged

Fig.-

Fig.4

5 z4EFF

Condition of T; Heat Exchanger by Crevice Corrosion3)

Pmcess

Preheater

Flowsheet

.

1.

Fig--9

Test Apparatus for *a.suzing of Inside

Surface

Oorrosion mtential of Heat Transfer htbe

Fig.-10 Corrosion Potential

of 304 Tube