The document discusses water treatment from the intake well to the boiler drum in a power plant. It covers: 1) Water treatment processes from intake to clarifier like alum dosing and chlorine dosing to remove solids. 2) Water treatment from clarifier to DM plant and softener plant using filters and ion exchange. 3) Dosing like hydrazine and phosphates in the boiler feedwater loop to control oxygen and pH. 4) The need for measuring parameters like silica, pH, conductivity and oxygen levels at various stages to monitor water quality and prevent corrosion in the system.

1. WATER ANALYSIS FROM INTAKE WELL TO BOILER
DRUM
SUBMITTED BY
PRIYANK MODI
BLA POWER PVT. LTD.
2X45 MW
NIWARI GADARWARA (M.P.)

2. CONTENT
 need for boiler water treatment
 WATER FROM INTAKE TO RESERVOIR
 WATER FROM RESERVOIR TO CLARIFIER
 Why alum dosing, Poly electrolyte dosing , Chlorine dosing required
 WATER FROM CLARIFIER TO DM & SOFTWATER PLANT
 WATER FROM dm tank TO BFP
 LP DOSING REQUIRED.
 Water from bfp to boiler drum
 HP DOSING REQUIRED
 BLOW DOWN Measurement
 Why Silica measurement required
 Why pH Measurement Required
 Why Conductivity Measured
 DO MEASUREMENT REQUIRED
 Why phosphate measurement required

3. WHAT IS THE NEED FOR BOILER WATER TREATMENT?
 Inhibit corrosion
 Prevent freezing of the water in the system
 Increase the boiling point of the water in the system
 Inhibit the growth of mould and bacteria
 Allow improved leak detection

4. WATER FROM INTAKE TO RESERVOIR
Intake Well Reservoir
LVL- 340 M
pH-8 to 8.5
DISTANCE 13 km pipe line
TURBIDITY –
(AT A TIME ONE OR TWO PUMP RUNNING) 18-100 NTU
Capacity
25000
cubic
mtr.
For Both
Press- 6
Kg/cm2
FLOW -
265
M3/HR
ON 1-
PUMP

5. WATER FROM RESERVOIR TO CLARIFIER
Capacit
y
25000
cubic
mtr.
For Both
CLARIFIE
R
STORAGE
TANK
(750 M3)
POLY
ELECTROLY
TE DOSING
(5400 LTR)
240 LPH
SOLID
CONTACT
REACTOR
RAW WATER
PUMPS
CHLORINE
DOSING
(300 LTR)
10 LPH
FLOW
187.26
M3/HR
ON CLARIFIER
STORAGE TANK
TURBIDITY- <5 NTU
pH- 7.5-8
Conductivity 230 mS/cm

6. WHY ALUM DOSING, POLY ELECTROLYTE DOSING , CHLORINE
DOSING REQUIRED
 ALUM DOSING :- The use of alum to remove suspended solids. It not only settles certain
hazardous chemicals and suspended solids but also bacterial colonies.
 POLY ELECTROLYTE DOSING:- Polyelectrolytes have got a wide range of applications right
from water purification, oil recovery, colour removal, paper making, mineral processing, etc.
polyelectrolytes are both flocculants as well as deflocculants depending upon the molecular
weight. A flocculant is essentially a solid liquid separating agent while a deflocculant is a
dispersing agent.
 CHLORINE DOSING:- In general, chlorine applied before any treatment is given (pre-
chlorination), during treatment (plant chlorination), or after normal treatment measures have
been carried out (post chlorination). Chlorine is a very effective disinfecting agent and has
been the agent of choice in reducing bacterial numbers in wastewater effluents.

7. WATER FROM CLARIFIER TO DM & SOFTWATER PLANT
CLARIFIE
R
STORAG
E TANK
(750 M3)
W
S
W
S
MGF FEED PMP
SOFTNER FEED PMP
DM WATER PLANT
SOFT WATER PLANT
Flow
APPROX
17 M3/HR
Flow 180
M3/HR

8. WATER FROM CLARIFIER TO DM
MGF FEED
PUMP
MULTI
GRADE
FILTER
ACTIVATE
D CARBON
FILTER
STRONG
ACID
CATION
DEGASSER
WATER
STORAGE
TANK
STRONG
BASE
ANAION
MIXED
BED
UF
ASSEMBL
Y
DM
WATER
STORAGE
TANK
Pr-2.3 Kg/cm2
FLOW-
8M3/HR
ON DM WATER STORAGE
TANK
SILICA – 0.02 ppm
TURBIDITY- 0
pH- 8.5 to 8.8 µS/cm
CONDUCTIVITY- 2 to 4
AFTER MIXED BED
SILICA – 0.02 ppm
TURBIDITY- 0
pH- 7.00
CONDUCTIVITY-<0.5µS/cm
MORPHILINE
FOR pH
BOOSTING

9. WATER FROM CLARIFIER TO SOFT WATER TANK
SOFT WATER
STORAGE
TANK
COOLING
TOWER
Flow 90
m3/hr.
SOFT WATER FEED
PMP
BRINE
MEASURIN
G TANK
ACTIVATE
D CARBON
FILTER
MULTI
GRADE
FILTER
W
S
SOFTNER FEED PMP
SOFTNER
ON COOLING TOWER
TURBIDITY-20
pH-8-8.5
CONDUCTIVITY-
3500µS/c
ON SOFT WATER
STORAGE TANK
SILICA –20ppb
TURBIDITY-2
pH-8-8.7
CONDUCTIVITY-150-
250µS/cm
DOSING-
1.Antiscalent
2.Hydrogensulphate

10. WATER FROM DM TANK TO BFP
DM TANK
CAPACITY- 200
M3
LEVEL- 7500 mmwc
W
S
DM TRANSFER PMP
DEARATOR TANK
BFP-1 BFP-2
TO BOILERON DM TANK
SILICA –0.02ppm
TURBIDITY- nil
pH- 8.80-9.20
CONDUCTIVITY-0.2
ON DEARATOR
SILICA – < 20 ppb
TURBIDITY- 0 NTU
pH-8.8-9.2
CONDUCTIVITY- 5µS/cm
OXYZEN- < 7ppb
BOILER FEED PMP
LP DOSING
HYDRAGENE
FOR O2
REMOVE

11. LP DOSING (LOW PRESSURE ) REQUIRED
 Dissolved oxygen in feed water causes serious corrosion.
 Hence “oxygen scavengers” or “de-oxygenators” are dosed
into feed water.
 Dosing done into feed water stream, either at BFP suction or
at deareator, at low pressure.

12. DOSING CHEMICAL – L.P. DOSING
 Hydrazine Hydrate Solution, in concentrations of about 0.10% is used for oxygen scavenging
purposes.
 Sodium Sulphate Solution, is also used as Oxygen Scavenger.
 Amonia Solution (about 1-2 %) is also used, for pH control of feed water.
 Similarly Morpholine is also used.
 Caustic Soda Solution is also used, for pH control of feed water.

13. WATER FROM BFP TO BOILER DRUM
BFP HPH-1 HPH-2
ECONOMISER
BOILER
DRUM
HP DOSING
TRI
SODIUM
PHOSPHAT
E FOR
MAINTAING
PH
FINAL
SUPER
HEATER
BLOW DOWN
ON BOILER DRUM
SILICA – <1000ppb
pH-9.2to9.50
CONDUCTIVITY-<6.0
ON SUPER HEATER
SILICA –0.02ppm
pH-8.80—9.20
CONDUCTIVITY- <0.2
SODIUM- 0—10ppb

14. HP DOSING (HIGH PRESSURE) REQUIRED
 Corrosion Rate of M.S. surface is lowest when pH is between
9-10.
 Dosing is therefore done, to maintain pH & reducing Scaling.
 Generally Solution dosed into drum under full boiler pressure.

15. DOSING CHEMICALS : H.P. DOSING
 Phosphate Solution (combination of di-sodium and tri –sodium phosphate) is
generally used, in concentrations from 2.5% to 7.5%.
 Exact dosage Rate depends on pH variation of water in Drum.
 It prevents scale formation from low remaining levels of hardness which may
have escaped treatment.
 Sodium Phosphate causes the hardness to precipitate to the bottom of the
boiler where it can be blow down.

16. BLOW DOWN MEASUREMENT
The following information is required:
1) Boiler water TDS (PPM)
2) Feed water TDS (PPM)
3) The quantity of steam which the boiler generates, usually measured in kg / h
Boiler water TDS measurement :-
conductivity (µS / cm) x 0.7 = TDS in parts per million (at 25°C).
F=Feed water TDS (ppm)
S=Steam generation rate (kg / h)
B=Required boiler water TDS (ppm)

17.  THE PRESENCE OF SILICA IN THE STEAM AND WATER CIRCUITS OF A POWER GENERATION
PLANT IS ASSOCIATED WITH A NUMBER OF PROBLEMS BOTH IN THE SUPER HEATER AND
TURBINE SECTIONS.
 THE SOLUBILITY OF SILICA IN STEAM INCREASES WITH PRESSURE. HENCE THERE ARE
CHANCES OF SILICA CARRYOVER. THE PRESENCE OF SILICA IN THE STEAM CAN LEAD TO
DEPOSITION IN SUPERHEATED TUBES AND ON TURBINE BLADES WHICH MAY LEAD TO LOSS OF
EFFICIENCY AND TURBINE BLADE FAILURE.
 SILICA IN THE STEAM CYCLE CAN RESULT IN DEPOSITION OF A “GLASS” LAYER ON SURFACES,
RESULTING IN A LOSS OF THERMAL PROCESS EFFICIENCY.
 DEPOSITION OF SILICA ON THE TURBINE BLADES CAN RESULT IN THE TURBINE BECOMING
IMBALANCED, REDUCING EFFICIENCY AND, IN EXTREME CASES, CAUSING EXTENSIVE DAMAGE
TO THE TURBINE.
WHY SILICA MEASUREMENT REQUIRED

18. WHY PH MEASUREMENT REQUIRED
The steam which goes to the turbine has to be ultra pure. The pH value of the feed
water gives direct indication of alkalinity or acidity of the water.
The ultra pure water has pH value of 7.
In a steam circuit, to keep the pH value of feed water at slight alkaline levels.
It helps in preventing the corrosion of pipe work and other equipment.
pH Analyzers are recommended at following location in a steam circuit : high
pressure heaters, DM Makeup, CEP discharge

19. WHY CONDUCTIVITY MEASURED
Conductivity is an important parameter for detecting any contamination of steam
in the boiler circuit.
Conductivity of pure water is almost zero (1-2 μ Siemens)
Ingress of any kind of dissolved impurity will raise conductivity instantly.
Thus conductivity is an important parameter for the detection of leakages.

20.  The DO determination measures the amount of dissolved (or free) oxygen present in water or wastewater
 At elevated temperature dissolved oxygen causes corrosion which may cause puncture and failure of
piping and components respectively.
 Dissolved oxygen also promotes electrolytic action between dissimilar metals causing corrosion and
leakage at joints and gaskets.
 Mechanical Dearation and chemicals scavengers additives are used top remove the DO.
 DO monitoring is imperative in power stations using neutral or combined operating conditions
(pH 7.0-7.5 or 8.0-8.5)
 In steam Circuit where DO monitoring is required are Deaerator Inlet and Outlet (Feed water, Condenser
& Deaerator Outlet) .
WHY DO MEASUREMENT REQUIRED

21. WHY PHOSPHATE MEASUREMENT REQUIRED
This treatment is used to precipitate the hardness constituents of water and
provide alkaline pH control, which will reduce boiler corrosion.
Maintains the sodium-to- phosphate molar ratio – (2.1 to 2.9)
This ratio must be maintained to prevent formation of phosphoric acid
(ratio below 2.1) or free sodium hydroxide (ratio above 2.9)
The use of phosphate analyzer is to provide a safe alkaline environment in
the boiler.