Home

Contact Us

Corporate Profile

Products
Applicable Standards
Interpretation
Steam Purity Limits
Testing Schedule
 		  
 

Steam Purity Limits for Steam Turbines - Key Parameters
Location Parameter µg/kg Expected range Limit Value Action within 1 week Action within 24 h Action within 1 h
Live Steam c.con (µS/cm(250C)) 0.06 - 0.2 0.2a.b 0.2 - 0.5c 0.5 - 1.0 >1.0
  Sodium 0-5d 5d 5-10 - -
  Silica 3 - 5 20 - - -
  Irone 2 - 5 20 - - -
  Copper f 0 - 1 3 - - -
Attemperator Spray c.con (µS/cm(250C))

 as live steam
  Sodium
  Silica
  Irone
  Copper f
  • For conventional phosphate dosing, a limit value of 0.3 µ S/cm (250C) may be applied, provided it can be shown that the dominant contribution to the additional conductivity is due to the phosphate ion.
  • higher value may be acceptable when an organic oxygen scavenger or volatile pH conditioner is used, provided that it is shown. For example, by analysis of chloride and sulphate that the increase is not due to aggressive contaminants.
  • If chloride exceeds 20 µg/kg, action within 24 h is necessary.
  • Values depend on boiler dosing , 5µg/kg is normally attainable as a limit value under AVT. In some plant, up to 10 µg/kg may be appropriate under sodium compound dosing.
  • Iron may not need to be monitored in plant where there is no history of excessive iron transport
    problems. 
  • Only monitored in plant with copper alloy heat exchanger tubing, particularly high-pressure boiler
    systems.
  • Only used in conjunction with monitoring of saturated steam to indicate live steam purity.
Abbreviated Terms :
For the purpose of this technical specification, the following abbreviated terms are used :
AVT all volatile treatment
BWR boiling water reactor
c.con cation conductivity
CT caustic treatment
EPT Equilibrium phosphate treatment
FAC flow accelerated corrosion
IWC International Water Conference
OT oxygenated treatment
PT Phosphate treatment
PWR pressurized water reactor
Reference : TS 61370 © IEC : 2002 Steam Purity Limits for Steam Turbines - Key Parameters
       
Steam Turbines - Steam Purity
High c.con Chloride sulphate Condenser leak Check condenser
Demineralization plant failure Check demineralization plant
Organic impurities from raw water Check demineralization plant
Increased organic additive decomposition Check dosing rates
Condensate polisher slippage Check condensate polisher operation
cation exchange resin fines Check condensate polishers
Carbon dioxide due to air inleakage at condenser Check condenser for leaks
High sodium   Condenser leak Check condenser
Increased boiler water dosing Check dosing rates
Increased boiler water carryover Check condition of boiler for foaming, high level or moisture separator defect
Demineralization plant failure Check demineralization plant
High Silica   Increased boiler water carryover Check condition of boiler as above
Demineralization plant failure Check demineralization plant
Increase in raw water non-reactive silica content Check raw water quality
Mixed bed condensate polisher slippage Check condensate polisher operation
High iron   High levels in feedwater and increased corrosion product transport by carryover or impure attemperator spray Check conditioning especially for low pH
Use of materials prone to iron oxide release Check material performance
High Copper   High levels in feedwater and increased corrosion product transport by carryover or impure attemperator spray. Check feedwater purity for high oxygen or high pH
Reference : TS 61370 © IEC : 25002 Steam turbines - steam purity actions on deviations from guidelines
 

@2006 Ecosustain Energy Systems Pvt. Ltd. All rights reserve
 Contact Ecosustain Energy Systems Pvt. Ltd.