8/9/2019 Boiler Water Treatment (16-20).ppt
1/23
Water Systems: water
conditioning for Process and
Boiler use•Prajakta Desai
•Niranjani Deshpande
•Sukhada Dhone•Sanuj Dubey
•Neille !ernandes
8/9/2019 Boiler Water Treatment (16-20).ppt
2/23
"ntroduction
• "ndustrial water
# Process water: Water that is used for$ or
comes in contact with an end product or the
materials used in an end product%
# Boiler feed water
# Water that seres in any leel of the
manufacturing process• &ommon contaminants: &a$ 'g$ !e$ (l$
Silica$ silt$ oil
8/9/2019 Boiler Water Treatment (16-20).ppt
3/23
Impurity Resulting in Got rid by
Soluble )ases *+S &orrosion of boiler tubes (eration$ deaeration andchemical treatment
,+
&,
Suspended
solids
Sediment and
turbidity
Sludge and scale carryoer &larification$ filtration and
chemical treatment
&arryoer$ foaming andcorrosion,rganic matter
Dissoledcolloidal solids
,il and grease !oaming$ deposition &oagulation$ filtration
*ardness &a
- 'g
Scaling$ inhibits *.$ boiler tube
burn thru
Softening and internal treatment
Na$ (lkalinity$Na+&,/$
!oaming$ corrosion$embrittlement
"on e0change$ deioni1ation
Sulphates *ard scales if &a present Deioni1ation
&hlorides Priming$ foaming Deioni1ation
!e$ 'n 2usting$ resistence to *. (eration$ filtration$ ion e0change
Silica Scaling Deioni1ation$ lime3soda process
8/9/2019 Boiler Water Treatment (16-20).ppt
4/23
.reatment 'ethods
• 40ternal .reatment
• "nternal .reatment
8/9/2019 Boiler Water Treatment (16-20).ppt
5/23
40ternal methods of
conditioning• &larification
• !iltration
• "on e0change• 'embrane separation
8/9/2019 Boiler Water Treatment (16-20).ppt
6/23
&larification
• 2emoes all types of solids - large particles # sediments$ oil$
natural org% matter$ colour etc%
• &onsists of 5 steps # screening$ coagulation3flocculation$
sedimentation$ fine filtration%
• Screening protects downstream units from large$ easily separableobjects%
• .hree types:
# !ine screening 6spacing 7 89 mm
# 'edium screening 6spacing 89 # 59 mm
# &oarse screening 6spacing ; 59 mm
• &oagulation3flocculation remoes suspended solids - colloidal
particles%
8/9/2019 Boiler Water Treatment (16-20).ppt
7/23
&larification 6contd%
• "mportant factors # elocity gradient$ time$ p*
• !lotation # to separate particles haing density lesser
than water%
• .hree types: # Natural
# (ided
# "nduced
• "nduced flotation facilitated through bubbling of air< +types #
# Dissoled air flotation 6D(! 6bubbles of 59 # =9 µm
# 'echanical flotation 6bubbles of 9%+ # + mm
8/9/2019 Boiler Water Treatment (16-20).ppt
8/23
!iltration
• Separates undissoled solids from water by means of a
filter 3 porous substance$ membrane or permeable fabric%
• .hree types of filtration:
#'icro filtration 6pore si1e 9%8 # 89 >m
# ?ltra filtration 6pore si1e 83899nm
# Nano filtration 6pore si1e 7 8 nm
• 'icro filtration # remoes bacteria< used for biological
wastewater treatment$ effluent treatment$ separation ofoil3water emulsions%
• ?ltra filtration 3 separation of suspended solids$ colloids$
bacteria$ irus%
8/9/2019 Boiler Water Treatment (16-20).ppt
9/23
!iltration 6contd%
• + ultra filtration module configurations:
# Pressuri1ed system or pressure3essel configuration
# "mmersed system
• Nano filtration # water softening$ decolouring$ micro3pollutant remoal 6org% matter$ heay metals$ pesticides%
• ?ltra - nano filtration # pressure drien processes%
• Pre3treatment # protects filtration membranes<
microfiltration # pre3filter for ultra filtration and so on%
8/9/2019 Boiler Water Treatment (16-20).ppt
10/23
"on 40change
• 2esins 3 acidic@basic radicals with ions fi0ed on them< e0changed
with ions present in water%
• .heoretically remoes 899 A of salts< does not remoe organics$
irus or bacteria%
• + types of resins # gel type 6microporous and macroporous orloosely cross3linked type%
• / systems of resin beds:
# Strong acid cation Strong base anion
# Strong acid cation weak base anion Strong base anion # 'i0ed3bed Deioni1ation
• "on e0change plant # softens water$ remoes heay metals$
produces deminerali1ed water%
8/9/2019 Boiler Water Treatment (16-20).ppt
11/23
2eerse ,smosis 62,
• By applying pressure greater than osmotic pressure$ water flows from
the higher concentration solution to lower one%
• 'ostly used for desalination< also for waste water treatment%
• (pplied pressure depends on the type and salinity of water%
• Working pressure: # 7 8C bar for tap water 67 8C99 ppm
# 8C # +C bar for brackish water 67 999 ppm
# C9 # =C bar for sea water 6/C999 # 5C999 ppm
• 2, plant preceded by pretreatment to aoid membrane fouling by
sediments$ bacteria$ metal o0ides - chlorine%
• 2, permeate water more acidic than the feed water due to dissoled
&,+% &ommon post3treatment are p* neutrali1ation and
reminerali1ation%
8/9/2019 Boiler Water Treatment (16-20).ppt
12/23
4lectrodioni1ation
• &ombines membrane separation and ion3
e0change to proide high efficiency
deminerali1ation process%
• 4lectric potential transports - segregates chargedaEueous species%
• 4lectric current continuously regenerates resin< no
need for periodical regeneration%
• Deioni1ation chamber 3 ion e0change resin$
packed between cationic - anionic e0change
membranes%
8/9/2019 Boiler Water Treatment (16-20).ppt
13/23
4lectrodioni1ation
• (dantages
# continuous operation
# eliminates use of chemicals for regeneration
# low power consumption
• Disadantages
# Not used for water with hardness ; 8
# reEuires purification pretreatment
# Pre3remoal of &,+
8/9/2019 Boiler Water Treatment (16-20).ppt
14/23
"nternal .reatment methods
• Deaerators:
• Dissoled non3condensibles: ,+ and &,+
• Pitting and corrosion• 'echanical deaeration: reducing solubility of gases
# "ncreased temperature # Decreased partial pressure oer the water # &ommonly used purge gas: steam # (dantages:
# No added impurities # 4asily aailable # (lso proides heat
# Pressure@Facuum operation$ GHA of total and free is remoed
• &oupled with chemical scaengers for completedeaeration
8/9/2019 Boiler Water Treatment (16-20).ppt
15/23
&orrosion control
• p* control # Different for different components$ different
alloys
# &S : optimum p* I H%+ to H%J at feed watertemperatures
# 'S : optimum p* I %C to 8+%= in boilers
# &u and &S : % to H%+
# 'aintained by addition of amines or smallamount of caustic soda
# (oidance of addition of ammonia
8/9/2019 Boiler Water Treatment (16-20).ppt
16/23
&orrosion control contd%
• ,0ygen control: during operation
# &hemical Scaengers added to feedwater and
condensates
• Sodium sulfite$ bisulfite$ hydra1ine• Kuinone$ ascorbate
# &ommon entry: between deaerator and storage
Sodium sulfite: easy to handle$ safe$ for pressures of 7 =9 bar$
solid addition to system$ decomposition to corrosie gases
*ydra1ine: no solid addition$ high pressures$ but to0ic$ handling
issues$ (mmonia liberation$ slower reaction
# &onstant sampling and monitoring
8/9/2019 Boiler Water Treatment (16-20).ppt
17/23
&orrosion &ontrol contd%
• &ontrol: downtime and storage # ,0ygen in3leakage and p* lowering
# Dry storage: long downtime$ month or more
• &ompletely dried• (pplied dessicants like Euicklime$ silica gel$
actiated alumina
# Wet storage: short downtime
• &leaning$ inspection and filling with deaeratedfeedwater
• (ddition of scaenger$ heat addition
8/9/2019 Boiler Water Treatment (16-20).ppt
18/23
Deposits
• Scaling@deposition from carryoer
• &arbonate@Phosphate control # (ddition of certain amounts of carbonate@phosphate for ensuring
precipitate in the form of salts% Preention of Sulphates
# !or remoal of hardness$ &a and 'g # Precipitation in bulk instead of at walls$ non3adherent
• ,rganic supplements: fluid sludge formation 6polymeraddition # Bottom blowdown remoes sludge
• &helant control
• &ombination of addities
• Blowdown
8/9/2019 Boiler Water Treatment (16-20).ppt
19/23
&ase study 3Boiler tube failure
• Failure mode :Oxygen corrosion
• Result: 3-5 shutdowns.
• Reasons 3"mproper deaeration%
3*igh leel of dissoled o0ygen%
3Leakage in recirculator pump%
8/9/2019 Boiler Water Treatment (16-20).ppt
20/23
Boiler tube failure
8/9/2019 Boiler Water Treatment (16-20).ppt
21/23
est practices
• !aintain the e"uipment properly %
• #ontrol the composition o$ the boiler
$eed water
• Identi$y optimal chemicals $or the
pre%ention o$ biological growth
• &lectrically powered water conditioningunits
8/9/2019 Boiler Water Treatment (16-20).ppt
22/23
Best practices3continued
• 'retreatment o$ ma(eup water
• !aterials o$ construction
• Optimi)e the $re"uency o$ cleaningboilers.
• Recent techni"ues
- 'agnetic water treatment.
8/9/2019 Boiler Water Treatment (16-20).ppt
23/23
.*(NM ,?
Top Related