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WATER ANALYSIS FROM INTAKE WELL TO BOILER DRUM
SUBMITTED BY
PRIYANK MODI
BLA POWER PVT. LTD.2X45 MW
NIWARI GADARWARA (M.P.)
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
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
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
WATER FROM RESERVOIR TO CLARIFIER
Capacity
25000 cubic mtr.
For Both
CLARIFIER
STORAGE TANK (750
M3)
ALUM DOSING (2200 LTR)
100 LPH
POLY ELECTROLYTE 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
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 de flocculants depending upon the molecular weight. A flocculant is essentially a solid liquid separating agent while a de flocculant 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.
WATER FROM CLARIFIER TO DM & SOFTWATER PLANT
CLARIFIER
STORAGE 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
WATER FROM CLARIFIER TO DM
MGF FEED PUMP
MULTI GRADE FILTER
ACTIVATED
CARBON FILTER
STRONG ACID
CATION
DEGASSER WATER
STORAGE TANK
STRONG BASE
ANAION
MIXED BED
UF ASSEMBLY
DM WATER
STORAGE TANK
Pr-2.3 Kg/cm2FLOW- 8M3/HR
ON DM WATER STORAGE TANK SILICA – 0.02 ppmTURBIDITY- 0pH- 8.5 to 8.8 µS/cmCONDUCTIVITY- 2 to 4
AFTER MIXED BEDSILICA – 0.02 ppmTURBIDITY- 0pH- 7.00CONDUCTIVITY-<0.5µS/cm
MORPHILINE FOR pH
BOOSTING
WATER FROM CLARIFIER TO SOFT WATER TANK
SOFT WATER STORAGE
TANK
COOLING TOWER
Flow 90 m3/hr.
S
M
SOFT WATER FEED PMP
BRINE MEASURING
TANK
ACTIVATED 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.Antiscalent2.Hydrogensulphate
WATER FROM DM TANK TO BFP
DM TANK
CAPACITY- 200 M3
LEVEL- 7500 mmwcW
S
DM TRANSFER PMP
DEARATOR TANK
BFP-1 BFP-2
TO BOILER ON 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
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.
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.
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 –0.02ppmpH-8.80—9.20CONDUCTIVITY- <0.2SODIUM- 0—10ppb
TURBINE
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.
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.
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)
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
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
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.
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
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.