MS/HRH TEMPERATURE RISING/FALLING FAST

MS TEMPERATURE RISING FAST

Likely causes

·         Inadequate spray due to malfunctioning of spray control valves.

·         Excess airflow.

·         Burner tilt stuck in up position

·         Leakage in the spray line.

·         Low feed water temperature.

·         Boiler firing raised in top elevation

·         Heavy furnace slagging

·         Spray isolation valve in close condition

Plant response

·         MS temperature high alarm will appear.

·         Spray control valves will go for further opening.

·         If temperature is very high, turbine will trip.

Parameters of concern/Adverse effects

·         MS/RH temperatures

·         MS temp at turbine inlet

·         HP exhaust temperature.

·         Spray quantity/ FCV differential pressure.

·         Tilt position

·         Metal temp. raise above design value will reduce tube life drastically

Immediate expected or desirable operator action

·         Make burner tilt fully down

·         Take MS spray control to manual & raise spray quantity

·         Reduce firing in top elevation

·         If rate of pressure rise is more, then pick up load if margin is there.

·         Reduce airflow based on the O2 percentage.

·         Check spray station is properly lined up

Final correction activity

·         Start soot blowing, if slagging is more

·         Restore back the temp controls in auto if it has been taken in manual

·         Check for any malfunction of spray control valves & isolate such type of valve.

·         Burner tilt can be kept horizontal.

9. RH TEMPERATURE RISING FAST

Likely causes

·         Inadequate spray due to malfunctioning of spray control valves.

·         Excess airflow.

·         Burner tilt stuck in up position

·         Leakage in the spray line.

·         Low feed water temperature.

·         Boiler firing raised in top elevation

·         Heavy furnace slagging

·         HP exhaust temp is high

·         Spray isolation valve in close condition

Plant response

·         RH temperature high alarm will appear.

·         Amount of spray will rise.

·         Turbine will trip if RH temp reaches very high

Parameters of concern/Adverse effects

·         RH temperatures

·         RH temp at turbine inlet

·         HP exhaust temperature.

·         Spray quantity/ FCV differential pressure.

·         Tilt position

·         Metal temp raise above design value will reduce tube life drastically

Immediate expected or desirable operator action

·         Make burner tilt fully down

·         Take RH spray control to manual & raise spray quantity

·         Reduce firing in top elevation

·         If rate of pressure rise is more, then pick up load if margin is there.

·         Reduce airflow based on the O2 percentage.

·         Check spray station is properly lined up

·         Check HP exhaust temp is normal

Final correction activity

·         Start soot blowing if furnace slagging is there.

·         Keep the burner tilt in horizontal condition.

·         Restore back the control in auto if it has been taken in manual.

10. MS TEMPERATURE FALLING FAST

Likely causes

·         Tripping of mill

·         Sudden boiler pressure drop

·         Malfunctioning of spray control valves.

·         Spray station passing

·         Less air flow

·         Burner tilt fully down

·         High feed water temperature

·         Soot deposits on SH tubes

Plant response

·         MS temperature low alarm will appear.

·         Turbine will  trip if  MS  temp goes  very low.

Parameters of concern/Adverse effects

·         Ms temp

·         Spray quantity

·         Burner tilt

Immediate expected or desirable operator action

·         Close the spray control valves by taking it into manual.

·         Make burner tilt upward.

·         Check airflow &Rise if necessary.

·         Increase firing in top elevation

·         Reduce turbine load if pressure is dropping

·         Close spray station Block valve/ isolation valve if control valve is passing.

Final correction activity

·         Start LRSB operation

·         Observe for improvement in temperature.

·         Restore back the controls in auto (spray control)

·         Check for any malfunction of control valve & isolate it.

11. RH TEMPERATURE FALLING FAST

Likely causes

·         Tripping of mill

·         Sudden boiler pressure drop

·         Malfunctioning of spray control valves.

·         Spray station passing

·         Less air flow

·         Burner tilt fully down

·         High feed water temperature

·         Soot deposits on RH tubes

Plant response

·         RH temperature low alarm will appear.

Parameters of concern/Adverse effects

·         RH temp

·         Spray quantity

·         Burner tilt

·         Load

Immediate expected or desirable operator action

·         Close the spray control valves by taking it into manual

·         Make burner tilt upward

·         Check airflow &Rise if necessary

·         Increase firing in top elevation

·         Reduce turbine load if pressure is dropping

·         Close spray station Block valve/ isolation valve if control valve is passing.

Final correction activity

·         Start LRSB operation

·         Observe for improvement in temperature.

·         Restore back the controls in auto (spray control)

·         Check for any malfunction of control valve & isolate it.