B
Frame-V gas turbine is dual fuel type (NG & HSD). It was running in NG 100%. We tried to change over the fuel from NG to HSD. After selecting HSD, liq fuel stop valve opened and HSD on skid pump clutch engaged. After 15 sec turbine tripped in low liq fuel pressure (63FL-2).
Before taking the HSD in line, leak attending job carried out and line was drained from HSD stop valve to burner nozzle portion. Before HSD stop valve the HSD pressure was stable at 4.5 kg/cm2 and there was no dip in the pressure. This pressure is maintained by HSD forwarding pump with a pneumatic control valve.
As per logic, the on skid HSD screw pump suction side pressure switch (63FL-2) set point is 0.73 kg/cm2 with time delay 15 sec.
HSD forwarding pump flow capacity is 30 m3/hr with discharge pressure 9 kg/cm2.
My question is,
1. I am confusing about the reason for which this pressure sustained less than 0.73 kg/cm2 for a prolonged time for 15 sec?
No leak / pressure drop found later on the same line. The line volume may be hardly 1 m3. Low pressure sensed after stop valve opening.
2. When the turbine tripped, Gt was running at 100% gas, liquid fuel was not in line till then. Why the turbine tripped on that condition? Only de-clutching of the HSD screw pump was sufficient to save the pump, the system could have continue to run on GAS?
Please enlighten.
Before taking the HSD in line, leak attending job carried out and line was drained from HSD stop valve to burner nozzle portion. Before HSD stop valve the HSD pressure was stable at 4.5 kg/cm2 and there was no dip in the pressure. This pressure is maintained by HSD forwarding pump with a pneumatic control valve.
As per logic, the on skid HSD screw pump suction side pressure switch (63FL-2) set point is 0.73 kg/cm2 with time delay 15 sec.
HSD forwarding pump flow capacity is 30 m3/hr with discharge pressure 9 kg/cm2.
My question is,
1. I am confusing about the reason for which this pressure sustained less than 0.73 kg/cm2 for a prolonged time for 15 sec?
No leak / pressure drop found later on the same line. The line volume may be hardly 1 m3. Low pressure sensed after stop valve opening.
2. When the turbine tripped, Gt was running at 100% gas, liquid fuel was not in line till then. Why the turbine tripped on that condition? Only de-clutching of the HSD screw pump was sufficient to save the pump, the system could have continue to run on GAS?
Please enlighten.