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.