Feed Water Contamination

8/11/2019 Feed Water Contamination

1/13

POWER PLANTFEED WATER CONTAMINATION

MONITORING- EARLY

DETECTION ACTIONS - EFFECTS


2/13

MONITORING

ANALYSERS CATION CONDUCTIVITY PH MONITORING CONDUCTIVITY SILICA RESIDUAL OXYGEN SODIUM CHLORIDE


3/13

CATION CONDUCTIVITY

The online measurement of conductivity afterwater has passed through a column ofstrongly acidic cation-exchange resin is used toindicate the presence of potentially corrosiveionic contaminants. The technique may bereferred to as cation conductivity or acid

conductivity in some documentation.


4/13


5/13

Thus, conductivity after cationexchange is extremely effective forrapidly indicating the onset of

condenser leakage, particularly atseawater-cooled plants, and alsofor detecting contaminated

makeup water


6/13

PH MONITORING

Turbine condensate Lab Feed water online & Lab Drum online & lab


7/13

Other Analyzers for monitoring

Total conductivity Drum water

Silica drum saturated steam Dissolved oxygen turbine condensate-Lab Sodium tracer turbine condensate- not

installed in Khobar Plants Chloride tracer live steam not installed in

Khobar Plants


8/13

Early detection of condenser leak

TC cation conductivity Feed water conductivity Live steam conductivity

Off scale > 1 s/cm Off scale > 1 s/cm Off scale > 0.5 s/cm


9/13

CCR operator role

TC cation conductivity High & off sacle Alert CRS & Lab

After few minutes if feed water Cationconductivity started raising raise alarm toLab & CRS.

Simultaneous raise of live steam Cationconductive increase above 0.2 s/cm confirmscontamination in the system


10/13

SCE INVESTIGATION As soon as TC cation conductivity is Off scale

contact lab and arrange to take sample of Turbinecondensate, Feed water and Live steam samplessame time .

Take control of the unit and watch all parameters As soon as Feed water, Economiser & Live steam

Cation conductivities start increasing take

following action- Do not wait for lab result Live steam conductivity raise will result in brine

condensate Conductivity raise.

Inform lab about the contamination for fast action


11/13

SCE IMMEDIATE ACTIONS

Arrange to take CPP in service Takes time Inform local operator to reject Turbine

condensate maximum possible Open CBD maximum of 10 % Simultaneously reduce TG load fast and desal

load ( 65%) As soon boiler load is sufficiently reduced ( 350

t/hr) , close all attemparation valve (RL54/55/56 )TO STOP CONTAMINATING LIVE STEAM


12/13

SCE ACTION Contd,

If needed stop top burners to control Livesteam temperatures.

Reject turbine condensate completely toreject and close RM26S201/RM23S401.

Watch drum pH and feed water pH- anydrastic lowering of pH must be informed toLab for corrective action to improve pH

Watch drum conductivity fast raising mustbe informed to lab


13/13

Chemical Symbol Maximum Concentration

(ppm)

Sodium sulphite NA2SO 3 1.0

Sodium chloride NaCl 10.0

Sodium phosphate NA3PO 4 25.0

Sodium sulphate NA2SO 4 25.0

Silica oxide SiO 2 0.20

Maximum Allowable Impurities in Boiler Water

Documents

Feed Water Contamination