Boiler water treatment

1. 12/13/2022
BOILER WATER TREATMENT

2. 12/13/2022
Impurities in Water

3. 12/13/2022
IMPURITY
PROBLEM CAUSED
GASEOUS
Pitting Corrosion
Dissolved Oxygen
Carbon Dioxide Condensate Corrosion

4. 12/13/2022
Scaling
Corrosion
PROBLEM CAUSED
IMPURITY
SOLUBLE/IONIC
Calcium/Magnesium
Sodium/Potassium
Chloride/Sulfate
Carbonates/Bicarbonates
Hydroxides
Silica
Corrosion
Scaling/Foaming
Scaling/Foaming
Scaling/Deposition

5. 12/13/2022
IMPURITY
PROBLEM CAUSED
INSOLUBLE/NONIONIC
Suspended Solids/Silt Fouling
Colloidal Silica Scaling /Deposition
Oil/Organics Foaming/Carryover
OTHERS

6. 12/13/2022
Water- impurities related
problems in Boiler

7. 12/13/2022
• OVER HEATING OF TUBES
• REDUCTION OF HEAT TRANSFER
• CALLS FOR SHUT DOWN
• RESTRICTION OF WATER FLOW
SCALING
INADEQUATE MAKE UP WATER QUALITY
CONTAMINATED CONDENSATE LEAKAGE
OF TURBINE CONDENSORS/ PROCESS LEAKS
SCALE FORMING IONS
Ca ++,Mg ++,CO3--,HCO3 --,SiO3
Ca +2 HCO3 CaCO3 + H2O + CO2
Ca + SO4 Ca SO4
Ca + SiO3 Ca SiO3
Mg + SiO3 MgSiO3

8. 12/13/2022
SCALING
Location - Boiler water tubes

9. 12/13/2022
METAL LOSS,PITTING
LOSS OF PROTECTECTIVE OXIDE FILM
(DESIRED PROTECTECTIVE FILM IN BOILER
IS MAGNETIC IRON OXIDE, Fe3O4. OXYGEN
DESTRUCTS THE PROTECTIVE OXIDE FILM)
Fe3O4 + O2 --> 6 Fe 2O3
LOW pH / ALKALINITY
DISSOLVED OXYGEN
CORROSION

10. 12/13/2022

11. 12/13/2022
Oxygen related Corrosion in economizer tube

12. 12/13/2022
CONDENSATE CORROSION
BICARBONATES + HEAT CO2
CO2 + H2O H2CO3 ( CARBONIC ACID)
Fe + H2CO3 Fe (CO3)2
CARBONDIOXIDE
CORROSION

13. 12/13/2022
Oxygen pitting in feed water line

14. 12/13/2022
HIGH CAUSTIC
ALKALINITY
CAUSTIC CORROSION / EMBRITTLEMENT
Fe3O4 + 4NaOH = 2 NaFeO2 + Na2FeO2 + H2O
(Sodium ferroate)
Fe + NaOH = Na2FeO2(Sodium Ferrite) + H2
CORROSION

15. 12/13/2022
• AFTER BOILER DEPOSITS
• PLUGGED VALVES AND
TRAPS
• DEPOSITION ON TURBINE
BLADES
MECHANICAL
• HIGH WATER LEVEL
• INCOMPLETE SEPARATION
• OF STEAM& WATER
• HIGH STEAMING RATE
• BOILER DESIGN
• UNEVEN FIRE
DISTRIBUTION
• LOAD FLUCTUATIONS
CHEMICAL
• HIGH TDS (TOTAL DISSOLVED
SOLIDS)
• HIGH ALKALINITY
• LEAKAGE OF OIL /
ORGANICS
CARRYOVER
EFFECT

16. 12/13/2022
TURBINE DEPOSITS
Corroded blades Deposits on turbine before cleaning

17. 12/13/2022
BOILER
DEAERATOR
FW
MU
BD
CORROSION
SCALING
CORROSION
CARRYOVER
CORROSION
TURBINE
WATERSIDE PROBLEMS IN BOILER SYSTEM

18. 12/13/2022
Types of boiler feed water treatment
• External treatment
• Internal treatment

19. 12/13/2022
INTERNAL TREATMENT - OBJECTIVE
Malfunctioning In External Treatment
- RO / FILTERS / DM PLANT / DEAERATOR
• Change In Inlet Water Quality
• Increase In Inlet Quantity
• Decrease In Resin Exchange Capacity
• Improper Regeneration Of Resin

20. 12/13/2022
Internal Treatment - Need
To take care during upsets in water quality
To maintain the BFW/BW & Steam quality
as per specified norms.

21. 12/13/2022
INTERNAL TREATMENT- INSURANCE
• TO MINIMISE REPLACEMENT COST
Very low compare to replacement cost of
equipment
• TO AVOID POOR HEAT TRANSFER DUE TO
SCALING
Increases Fuel Consumption / Cost of steam
• TO AVOID PRODUCTION LOSS

22. 12/13/2022
BOILER
DEAERATOR
FW
MU
Steam
IBD
CBD
Safety,
Reliability
Efficiency
Longer Life
Internal Treatment

23. 12/13/2022
Internal Treatment - Various
Programs
Phosphate Hydroxide Program
Polyphosphate-Polymer Based
Coordinated Phosphate control
Oxygen scavengers
Neutralizing amines
All volatile treatment

24. 12/13/2022
Scale Control

25. 12/13/2022
Phosphate - Hydroxide Method
10 Ca ++ + 6 PO4 -- + 2 OH - Ca10(OH)2(PO4)6
0r
( 3 Ca3(PO4)2.Ca(OH)2)
Calcium Hydroxyapatite
In this method Trisodium Phosphate & Caustic are used to
maintain pH 10.5 - 11.2 . Calcium Precipitate as Calcium
Hydroxyappatite - Non adherent sludge - which is drained
during the blowdown.
Magnesium reacts with caustic to form magnesium Hydroxide
Mg(OH)2

26. 12/13/2022
Benefits
• Cost effective
• Boosting pH - also helps as corrosion inhibitor
Limitation
• Solid product / addition of TDS
• Addition of sodium forming sodium silicate -
accelerating carry over
• Can create problem of caustic corrosion

27. 12/13/2022
Coordinated Phosphate- pH Method

28. 12/13/2022
In this method no free caustic is maintained in the boiler water. The
alkalinity is maintained in the boiler by use of combinations of
Trisodium phosphate( Na3PO4 , Disodium phosphate( Na2HPO4) &
Monosodium phosphate(NaH2PO4).In this method the Sodium to
Phosphate ratios are maintained in the range of 2.2 to 2.8
Na3PO4 + H2O Na2HPO4 + NaOH
NaH2PO4 + NaOH Na2HPO4 + H2O
In this reaction Caustic generated is called as captive & not free
as the reaction is reversible
3 Addition of MSP reduces the pH but increases the PO4
2. Addition of DSP consumes the caustic & increases the PO4
1. Addition of TSP generates Caustic which increases the pH & PO4

29. 12/13/2022
Polyphosphate-Polymer Based treatment
3221/ 3222/3223

30. 12/13/2022
Polyphosphate + Polymer
• Polyphosphates are long chain phosphates which form
fairly soluble complexes with scale forming salts.
• The dispersing action of polyphosphate further helps
in keeping the boiler internals clean.

31. 12/13/2022
The long chain polymers having -ive charge ions
get attached to active site on growing crystalline
scale.
CH2 CH2 CH2
CH CH CH
COOH COOH COOH

32. 12/13/2022
STOPPING GROWTH OF SCALE FORMING CRYSTALS
Scale forming molecule
-tve charged ion of the Polymer

33. 12/13/2022
Further it acts as dispersing to disperse the scale forming
ions and helps to form sludge which can be drained out
during the blowdown.

34. 12/13/2022
Electronically Charged Ions Repulses
Scaling Ions
Dispersion

35. 12/13/2022
Benefits over conventional chemical - TSP
• Liquid - Less TDS addition/ ease of handling
• Blend of chemicals - multi-effect
• Better cleaning effect

36. 12/13/2022
Oxygen Scavengers
( 3100/3200 )

37. 12/13/2022
Oxygen scavenger
Na2SO3 + 1/2 O2 - Na2SO4
Sodium Sulfite Sodium Sulfate
1 ppm of Dissolved O2 requires 8 ppm of
Sodium Sulfite.

38. 12/13/2022
10
8
6
4
2
0
5 10 15 20 25 30
DISSOLVED
OXYGEN
mg/ltr
CONTACT TIME mins
Sodium Sulphite
(Uncatalysed)
Sodium Sulphite
(Catalysed)
Reaction rates for catalyzed and uncatalysed Sodium Sulfite for Water Temp of
20 Deg.C
CATALYSED SODIUM SULPHITE

39. 12/13/2022
N2H4 + O2 ---- H2O + N2
Hydrazine Nitrogen
6 Fe2O3+ N2H4 --- 4Fe3O4 + 2 H2O + N2
Ferric Hydrazine Magnetite Water Nitrogen
Oxide
Oxygen Scavenger

40. 12/13/2022
10
8
6
4
2
0
10 20 30 40 50 60
DISSOLVED
OXYGEN
mg/ltr
CONTACT TIME mins
Uncatalysed Hydrazine
Catalysed
Hydrazine
Reaction rates for catalyzed and uncatalysed Hydrazine for water Temp of
20 Deg.C
CATALYSED HYDRAZINE

41. 12/13/2022
Rate of reaction depends on
• Temperature
(every increase in temp by 18 deg F,doubles the reaction rate)
• pH
• Initial concentration of DO

42. 12/13/2022
Neutralizing amines
( 3334/3311/3333)

43. 12/13/2022
Neutralizing amines are used
• to maintain the pH of the feed water
• to maintain boiler water pH
• to protect the condensate system from corrosion

44. 12/13/2022
DOSAGE
• OXYGEN SCAVENGER
- Based on Feed water temperature
• SCALE / CORROSION INHIBITOR
( PHOSPHATE )
–Based on PO4 residual to be maintained
in boiler/ on blowdown
• NEUTRALIZING AMINE
- Based on BFW/BW/Condensate water - pH

45. 12/13/2022
Boiler Treatment recommended
Chemical Feed Points
BOILER
DEAERATOR
FW
MU
S
BD
Phosphate - 3
OS - 2
Amine - 1 or 1 and 2
3
1
2

46. 12/13/2022
Dosing Procedure
• All the chemicals are to be dosed on continuos basis ( 24 hrs )
with the dilution in water .
• Recommended 10 % dilution. However, it can vary according to
dosing system capacity
• All the dosages are based on feed water quantity except AVT
• AVT dose depends on make-up water quantity
Qty required in kg /day = Dose in ppm X FW quantity in MT/hr X 24
----------------------------------------------
1000

47. 12/13/2022
Monitoring
.
Monitoring of the treatment consists of
 Drawing and analyzing all the water samples including
condensate water for defined parameters at decided
interval on continuos basis
 Based on the analysis , take necessary actions to maintain
the desired water parameters in defined limits
 Record the analysis and actions taken
 In case of upset in the treatment, frequency of analysis
to be increased till upset comes to the normal

48. 12/13/2022
PROBLEMS IN SUGAR INDUSTRY
DROP IN BOILER WATER pH
ROOT CAUSE
CONDENSATE WATER - CARBOHYDRATES
AMINOO ACIDS
CONTAMINATION

49. 12/13/2022
DROP IN BOILER WATER pH
EXCESS DOSING OF CAUSTIC / ALKALINITY BUILDER
INCREASE IN CAUSTIC ALKALINITY
FOAMING
CARRYOVER
TURBINE BLADE DEPOSITION
SHUT DOWN

50. 12/13/2022
SOLUTION
CHECK INDIVIDUAL RETURN CONDENSATE
pH VERY FREQUENTLY
AFTER BOILING THE SAMPLE
IF CONTAMINATED -BY PASS PERTICULAR
CONDENSATE
AVOID EXCESS DOSING OF CAUSTIC / ALKALINTY
BIULDER
USE PREFERABLY STEAM CONDENSATE ONLY

51. 12/13/2022
Blow Down
% Blowdown = Salt in Feedwater x 100
Salt in Boiler Blowdown water
Exp :
TDS in BFW = 200
TDS in BW = 4000
Therefore % BD = 200 x 100 = 5%
4000

52. 12/13/2022
WATER ANALYSIS

53. 12/13/2022
Importance Of Water Analysis
• In case of BWC the success of the treatment
program depends upon the Chemicals selected
as well as monitoring of the results.
•Regular analysis of the water parameters gives
a timely indication of how the treatment program
is working.
•Corrective actions if any can be initiated
immediately.
•Root cause of failure if any can be found out.

54. 12/13/2022
WATER ANALYSIS
• Regular water samples analysis
• Follow STD procedures
• Calibration of instruments
• Correct sample analysis
• Accurate water analysis
• Corrective steps incase of upset

55. 12/13/2022
Parameters to be analyzed
•pH
•Conductivity/TDS
•Phosphate
•Sulfite/Hydrazine
•Silica
•Alkalinity
•Chloride
•Residual Amine Only incase of AVT

56. 12/13/2022
SINGLE WINDOW CONCEPT
Thermax as a unique group deals in combustion engineering as well as water
treatment
1.system Accountability
2.Availability of services/spares and other related products through our
other divisions.
3. Single window concept enhances Customer-supplier Relationship.

57. 12/13/2022
Our Boilers…………………… Our Solutions
1.Solution providers can be more effective and cost competitive
because of the in-house product knowledge.
2. Expertise and rich experience in boiler as well as in water treatment
3. Assured quality - ISO company

58. 12/13/2022