Hot Start-up
Start-up of Boiler within 2 Hrs of Tripping of Boiler is known as the Hot Start-up of Boiler.
1. Ensure the Drum level of Boiler. It should be at Normal water level.
2. Start Air Compressors.
3. Start Boiler Feed water Pump.
4. Start ID fan with ID damper in Zero position.
5. Open Start-up vent.
6. Slowly open damper of ID fan. Watch Drum level.
7. Regulate Boiler pressure by opening start-up vent.
8. Super heater temperature has to be maintained with the help of attemperator control valve.
9. Raise the Boiler pressure upto 45 Kg/cm2 and temperature to 485 deg C.
10. Open the drains of Main steam line in between Main Steam Stop Valve (MSSV) of Boiler and Turbine.
11. Open By-pass valve of MSSV.
12. Condensate, if any, will be drained out and main steam line heating will be carried out by opening of by-pass valve.
13. After ensuring proper Main steam line heating, open Main
14. steam stop valve.
15. Close all drains in main steam line.
16. Charge ESP when flue gas temperature at Economizer outlet reaches 160 deg C
17. Put drum level controller and attemperator controller in Auto mode.
18. Regulate the pressure of Boiler with the help of start-up vent.
19. Close Start-up vent as per the steam demand of TG set.
20. Normalize ID fan damper by gradual opening and loading of Boiler.
Charging of De-areator
It removes the dissolved gases from the condensate mechanically by following two laws
1. Henry’s Law
2. Dalton’s Law of Partial Pressure.
· According to Henry’s Law, Solubility of dissolved gases decreases by increasing water temperature. So by charging steam in Deaerator water temperature increases and soluble gases in condensate departs.
· According to Dalton’s Law of Partial Pressure Pm= Ps+Pa
Where Pm= Partial pressure of Mixture
Ps= Partial pressure of Steam
Pa= Partial pressure of Air
· The partial pressure of air present inside the Deaerator comes out
· through Deaerator vent for equilibrium state.
Procedure Of Charging
1. Ensure DM Storage Tank level is more than 60%.
2. Start DM Transfer Pump by opening Recirculation valve.
3. Ensure Deaerator level is 60%. If the level is less then take the make up water .
4. Open all drain lines of Pegging PRDS line and observe that condensate is completely drained out.
5. Slowly open Pegging PRDS pressure Control Valve and ensure that condensate is drained out completely. Then close the drains.
6. Gradually increase the pressure to 2.8 Kg/cm2 by increasing pegging PRDS pressure control valve.
7. Slowly heat the Deaerator by opening the heating line isolation valve and raise the Deaerator temperature to 90 deg C.
8. Open the before and after isolation valve of Deaerator Pressure Control valve. Then open the pressure control valve gradually. Slowly increase the Deaerator pressure upto 2 kg/cm2 .After that put the Deaerator Pressure control valve in Auto mode.
9. Start LP Dosing pump.
10. In LP Dosing Hydrazine is used. Hydrazine removes oxygen by chemical reaction.
11. EQUATION- N2H4+O2=2H2O+N2
12. By adding Hydrazine dissolved oxygen becomes water and Nitrogen gas releases.
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