Water Water ChemistryChemistry

T.P.S., Parli-V. Certified for ISO 9001-2000ISO 14001-2004

Presentation by

H. B. Zade. Sr. Chemist

Mother EarthMother Earth

The Greatest Chemist in the The Greatest Chemist in the UniverseUniverse

Water RouteWater Route

R/W Pump House

U-3,4,5 P. T. Plant

U-3,4 DM Plant

U-3,4,5 Soft.Plant

TPS,Colony DomesticMakeup To All Units

Makeup To All UnitsWith interconnection facility

Use Of ChemicalsUse Of Chemicals Pretreatment Plant

1. Alum: FeSO4 Al2(SO4)3.18 H2O

2. Poly Aluminum Chloride3. Bleaching powder : Ca(OCl)2

4. Hydrated Lime : Ca(OH)2

Softening Plant1. Common Salt : NaCl

Demineralization Plant

1. Hydrochloric Acid : HCl

2. Caustic Soda Lye : NaOH

3. Hydrated Lime : Ca(OH)2

Boiler Drum WaterBoiler Drum WaterTrisodium Ortho Phosphate: Na3PO4.12H2O

Na3PO4+H2O NaOH +Na2HPO4 (Maintains PH)

2Na3PO4+3CaSO4 Ca3(PO4)2+3Na2SO4

10Ca+6PO4+2OH 3Ca3(PO4).Ca(OH) 2 .

Calcium Hydroxy apetite

3Mg+2SiO3+2OH+H2O 3MgO.2SiO2.2H2O

Serpentine

Above soft sludges can be removed by CBD Operations

Feed Water Dosing1 Hydrazine hydrate: N2H4.H2O

N2H4 +O2 N2+H2O (Oxygen scavenger)

3N2H4 4NH3 + N2 (at temp. > 205 °c)

(Res.N2H4 at Eco. Inlet = 0.01 to 0.02 ppm)

2 Liq. Ammonia : NH4OH ( Maintains PH)

Condensate Dosing : Only N2H4.H2O At C E P Discharge as it passivates theCopper alloy component of LP heater coils & Acts also as Oxygen scavenger

Cond.tube leakage (What happens ? )

1: Cooling water mixes in condensate water2:Hardness salts get carried to boiler& deposit

in boiler tubes3:Increased concentration of DO causes pitting

corrosion in boiler tubes, corrosion in preboiler i.e..cond.,feed water heaters,de areator depositing corrosion products in high heat zones resulting BTL

4:Salts like MgCl2 causes Hydrogen Embrittlement resulting BTL

Cond.tube leakage (Indications) 1:Increases cation conductivity of

condensate (Limit 0.3 micromhos/cm) 2:Increases Na Con. of condensate (Limit 10 ppb) 3:Increases Blr Drum water parameters

like PH, Cond.,Silica, Alkalinity

Remedial Action To arrest CTL by adding saw dust(in case

it is minor) Withdrawal of Unit for attending CTL in

case Conden. Parameters exceed permissible limits

Limits; Sodium(Na) at CEP outlet: 10 ppb or Cation conductivity of condensate: 0.3 Micro mhos/cm

ETP IETP I

References:

CEGB Vol.V BHEL (Trichi) Text book of water chemistry by Linus Pauling (California) Personal experience

Thanking you all