2dm Plant Opr

8/11/2019 2dm Plant Opr

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DM Plant consists of two pressure vessels containing cation and aexchange resins.

Various types of ion exchange resins can be used for both the catand the anion process, depending on the type of impurities in theand what the nal water is used for.

DEMINERALIZATION PLANT


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USE OF DEMINERALISED WATER

he high!purity water from a demineralised plant is typically usedfor high pressure boiler feed where high!purity water is a re"uireme


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TYPES OF RESINS USED IN

DEMINERALISATION

he type of resins employed and selected depends on numerous factreated water "uality re"uired$nput water "ualityPresence of organic foulants

here is a vast range of resins to select from, e.g. enhanced capacityresins, gel polystyrene resins, clear gel resins, resins for water contaiorganic matter, resins to achieve low silica levels.


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WATER FLOW DIAGRAM

CLARIFLOCC

ULATORGRAVITY

FILTER

D.M.

PLANT

SOFTENINGPLANT

COOLING

WATER

U/G STORAGE

TANK

RAW

WATER

DRINKING

WATER

BOILER

MAKEUP

C.W.MAKEUP


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D.M. PLANT

WEAK

ACID

CATION

STRONG

ACIDCATIONACF

WEAK

BASE

ANION

STRONG

BASE

ANION

MIXED

BED

DEGASSER

D.M.

WATER

STORAGE

TANK


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From filter

water pumps

DM

water

storage

tank

ACF WAC SAC WBA SBA MB

DEGASSER

Air

To main plant forboiler make up

For circuit rinse

D.M. PLANT


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ACTIVATED CARBON FILTER

%ervice and &egeneration ' (ac) wash*

%$ ! %ervice $nlet%+ ! %ervice +utlet

($ ! (ac)wash $n

(+ ! (ac)wash +ut&+ ! &inse +ut

Air

vent

SO

SI

BO

RO

BI

o -ation

xchanger Drain


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ater "uality at di/erent stages of Demineralisation process#!

0eed water to DM plant

urbidity ! 12 34

5-0 out

&esidual chlorine ! 3il

urbidity ! 1 6.7 34

-ation xchanger out

3a ! 12 ppm Degasser out

Dissolved -+2 ! 17 ppm

D.M. PLANT


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5nion xchanger out

%ilica ! 1 266 ppb

-onductivity ! 1 86 s9cm

p: ! ;.< ! =.2

Mixed bed out

%ilica ! 1 26 ppb

-onductivity ! 1 6.8 s9cm

p: ! ;.< ! =.2

D.M. PLANT


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ypically, the cation resin operates in the hydrogen cycle.

he cations in the water 'i.e. calcium, magnesium and sodium* passthrough the cation exchange resin where they are chemically exchafor hydrogen ions.

he water then passes through the anion exchange resin where thanions 'i.e. chloride, sulphate, nitrate and bicarbonate* are chemicexchanged for hydroxide ions.

The fnal wate !"# th$% &"'e%% '"n%$%t% e%%ent$all( "! h()"an) h()"+$)e $"n%, wh$'h $% the 'he#$'al '"#&"%$t$"n "! &-e

CATION EC/ANGER

ANION EC/ANGER


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Chemica Reac!i"#$ i# Demi#e%ai&a!i"# '%"ce$$(

E)ha*$!i"# "+ ca!i"# %e$i#(R,- Na RNa -SO0

K RK -C Ca RCa -NO1 M2 RM2 -NO1

-CO1 3i# !he +"%m "+ ch"%i4e 5 3%e$i# i# 3 %em"6e4 78 $*'ha!e5 7ica%7"#a!e e)cha*$!e4 ae%a!i"# i#

#i!%a!e57ica%7"#a!e e!c.9 +"%m9 4e2a$$i+ie%9

Re2e#e%a!i"# "+ !he ca!i"# %e$i#:

R-Na NaC

R,K -C R- KC

R,Ca CaC R,M2 M2C 3e)ha*$!e4 3+%e$h 3%em"6e4/4%ai#e4

%e$i#9 %e$i#9 78 %i$i#29


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E)ha*$!i"# "+ a#i"# %e$i#(

A#i"# Re$i#(RO- -SO0 RSO0 -O

-C RC

-NO1 RNO1 3Mi#e%a aci4$ 3%e$i#

"7!ai#e4 +%"m i# e)ha*$!e4

ca!i"# e)cha#2e9 +%"m9

Re2e#e%a!i"# "+ !he a#i"# %e$i#(

A#i"# %e$i#( RSO0 NaO- RO- NaSO0 RC NaC

RNO1 NaN"1 3e)ha*$!e4 %e$i#9 3+%e$h 3%em"6e4 78

%e$i#9 %i#$i#29


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TYPES OF RESINS USED IN DEMINERALI:ATION PLANT;.S!%"#2 aci4 ca!i"# %e$i#$ 3SAC9(

The strong acid cation resin derived their exchange activity from sulphonic

acid group(-SO3H) phosphonic (H2O3-)! "hen operated on hydrogencycle these remove nearly all cations present in ra# #ater! The strong

acid cations can convert neutral salts into corresponding acids! $fter

exhaustion the resin can %e regenerated #ith H&l(') *a&l(+,) for

demineraliation and softening purpose. repectively!

.Wea< aci4 ca!i"# %e$i#$3WAC9(The #ea/ acid cation resins have 0&OOH group as exchange sites!

These resins have the capa%ility of removing all cations associated #ith

al/alinity to a much greater degree than S$& resin! These do not function

efficiently %elo# pH 1!,. so these cannot split neutral salts effectively! The

main asset of "$& resins is their high regeneration efficiency #hich notonly reduces the amount of acid reuired for regeneration. %ut also

minimies the #aste disposal pro%lem! These are useful #here there is

high degree of hardness and al/alinity! reuently these are used in

con4unction #ith a strong acidic polishing resin!


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1.S!%"#2 7a$e a#i"# %e$i#3SBA9(5The Strong %ase anion resins derived their functionality from

uaternary ammonium exchange sites!These are capa%le of

exchanging anions li/e &l-.H&O3-.Silica! T#o type of S6$ resins

are commercially availa%le and commonly referred as Type-7 Type-77!5Type-7 site have three methyl groups #hile in Type-77 resins an

ethanol group replaces one of the methyl groups! The Type-7 resin

has higher %asicity. greater chemical sta%ility %ut some#hat less

exchange capacity and lo# regeneration efficiency particularly#hen the resin is exhausted #ith monovalent anions i!e! chloride

and nitrate! 7t is effective against organics silica! The Type-7

resins are favoured for the high temperature applications #here

chemical sta%ility difference is most apparent!

5The Type-77 resin is less sta%le %ut having slightly more capacityand regeneration efficiency! 7n general. a Type077 S6$ resin is

recommended #here silica effluent uality is not as critical and

also #here a relatively high chloride and8or sulphate content

prevails in ra# #ater!5$fter exhaustion S6$ resin can %e regenerated #ith ' *aOH!


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0.Wea< 7a$e a#i"# %e$i#3WBA9(5"ea/ anion resins derive their functionality from primary

(9*H2).secondary(9-*H9) tertiary amine (93*)groups! The

#ea/ #ea/-%ase anion resins remove free minerals acidity(;$)such as H&l H2SO' %ut doesnt remove #ea/ly ionied acids

such silicic acid and %icar%onates!5The main advantage of #ea/ %ase exchangers is that they can

%e regenerated #ith stoichiometric amount of regenerant. and aretherefore. much more efficient! These have a higher capacity for

the removal of chlorides. sulphates!5 These are used in con4unction #ith S6$ in demineraliation

system to reduce regenerant cost and to attract organics there%y

protecting the more suscepti%le strongly %asic resins. and forservice in #hich car%on dioxide and silica are not important!

"here silica removal is not critical. "6$ may %e used %y

themselves in con4unction #ith air stripper to remove

&O2(degaser)!


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CATIONIC LOAD ( = M,a#>a%4$ !h%"*2h a 'ac# i# c"*#!e% c*%%e#! 4i%ec!i"# 78 mea#$ "+ a 7">e%.


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Cat$"n E+'han*e An) An$"n E+'han*e

DF 0 D"wn Fl"w

NF 0 N"11le 2-%h$n

Re*eneat$"n l$net" wea3

e+'han*e

DrainDrain

Weak Strong

SI

SO

SO

A'$)4Al3al$ $n5e't$"n

DF

Air

VentAir

Vent

NF

SI

BO

BO

BIBI

RO

RO

Se6$'e an) Re*eneat$"n


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Re ?2e#e%a!i"# "+ mi)e4 7e4 e)cha#2e% (

;. Re$i# $e'a%a!i"#/7aca$h2! acid and al/ali in4ection

3! acid and al/ali displacement 0 using


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he resin in the pressure vessel has about 76> free space abovethe resin.his free space allows bac)washing,removal of any entrainedsolids.

ater and acid9caustic regeneration is carried out in a down!?owdirection.

CO0CURRENT FLOW REGENERATION


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The e*eneant a'$) an) 'a-%t$' &a%%e% $n the "&&"%$te )$e'

the %e6$'e 2"w wate.W$th '"-nte02"w e*eneat$"n, the e*eneant &a%%e% th"the e%$n nea t" the "-tlet "! the -n$t .

COUNTER0CURRENT FLOW REGENERATION


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P"l$%h$n* #$+e) 7e)% '"#e a!te the 'at$"n an) an$"n%tan)a) 6e%%el%an), a% the na#e $#&l$e%, the( ae thee t" &"l$%h thewate.

The 7e) $% an $nt$#ate #$+ "! an$"n an) 'at$"n e%$n%.

MIED0BED DEMINERALISATION


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MIED BED

Se6$'e an) Re*eneat$"n

Air

Vent

SI

SODrain

Alkali injection

Aci injection

NF

$ir


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Ca!i"# E)cha#2e Mecha#i$m

S!a%! "+ %*# D*%i#2 !he %*# E#4 "+ %*#

Ca

M2

Na

Ca

M2

Na

Ca

M2

Na

Na

A#i"# E)cha#2e Mecha#i$m

SO0,

C,

SiO

SO0,

C,

SiO

SO0,

C,

SiO

Ca!i"# e)ha*$!i"# ea4$ !" Na eahie a#i"# e)ha*$!i"# ea4$ !" SiO ea


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R"e "+ WTP( T" '%"4*ce U!%a,'*%e >a!e%

SiO2: ? 2, pp%

H @ =!A and / @ ,!,As8cm (upto)R"e "+ 4i++e%e#! 7e4$ i# DM 'a#!

U#i! Rem"6e$ !he i"#ic "a45 "ea/ $cid &ation : $l/aline hardness (temperature hardness)5 Strong $cid &ation : permanent hardness Bslip from

"$&BeB*a

5 "ea/ 6ase $nion : ;$ (&l-SO-'.*O-3. -)5 Strong 6ase $nion : $ll anions slip from "6$ SiO2. slip

from degaser!C5 ;ixed 6ed : ionic slips from previous unit-1

(final polisher)

5


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Than3%

2dm Plant Opr

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