2dm plant opr
TRANSCRIPT
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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%