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During the startup of the Gas turbine, It was observed that the only Combustion Chamber #3 did not see the flame after GT firing sequence. Rest 11 nos. of chambers get light properly.
* Non availability of flame in CC#3 leads to higher exhaust temp. spread and in turn some time leads to trip the machine in combustion trouble trip.
* However, It was also experienced that if GT was kept in crank mode for longer duration say 30 min or more & then start the firing sequence , some time CC#3 see the flame at HP rotor speed above 54% and immediately after that exhaust temp. spread reduced to min. value and then machine smoothly reaches to min. governor speed.
* Maintenance team has simulated and checked the Ignition system, flame scanner, IGV, SRV, GCV and found working satisfactory.
* Six month back HGPI was carried out & then after only mainly machine startup problem observed.
* The GT nozzles are duel fuel type but running only on Natural gas. Liquid fuel is isolated permanently . However, Atomizing airline is on and same is connected to the fuel nozzles.
-- Kindly help me to understand why CC#3 don't see flame during firing sequence and only after 54% of HP rotor speed see the flames.
-- what could be the root cause of this typical problem?
* Non availability of flame in CC#3 leads to higher exhaust temp. spread and in turn some time leads to trip the machine in combustion trouble trip.
* However, It was also experienced that if GT was kept in crank mode for longer duration say 30 min or more & then start the firing sequence , some time CC#3 see the flame at HP rotor speed above 54% and immediately after that exhaust temp. spread reduced to min. value and then machine smoothly reaches to min. governor speed.
* Maintenance team has simulated and checked the Ignition system, flame scanner, IGV, SRV, GCV and found working satisfactory.
* Six month back HGPI was carried out & then after only mainly machine startup problem observed.
* The GT nozzles are duel fuel type but running only on Natural gas. Liquid fuel is isolated permanently . However, Atomizing airline is on and same is connected to the fuel nozzles.
-- Kindly help me to understand why CC#3 don't see flame during firing sequence and only after 54% of HP rotor speed see the flames.
-- what could be the root cause of this typical problem?