Greetings to all
The unit I speak about is 7FA turbine.
Recently we had a trip on loss of flame because the hydraulic pressure went very low (650 Psi). the standby-pump started and got the pressure back to normal after 5 seconds. I believe the accumulator was not charged properly because there was no reaction to the decrease of the hydraulic pressure.
When the hydraulic pressure was decreasing, the WATT was also decreasing with it linearly. but the IGV remained in its position which caused Loss of Flame Trip.
My question is that, Based on my understanding of GCV and IGV control. Once the feedback equals the reference, the oil will be locked inside the actuator. So a loss of hydraulic pressure should not affect the control unless you want to actuate the valve. Maybe closing of GCV valve happened because it is constantly moving 0.5% up and down, so it is permitting a small amount of oil to the actuator. IGV was not affected because the degree usually is stable not moving up and down. this is my interpretation of the situation happened.
Anyone can comment and clarify?
The unit I speak about is 7FA turbine.
Recently we had a trip on loss of flame because the hydraulic pressure went very low (650 Psi). the standby-pump started and got the pressure back to normal after 5 seconds. I believe the accumulator was not charged properly because there was no reaction to the decrease of the hydraulic pressure.
When the hydraulic pressure was decreasing, the WATT was also decreasing with it linearly. but the IGV remained in its position which caused Loss of Flame Trip.
My question is that, Based on my understanding of GCV and IGV control. Once the feedback equals the reference, the oil will be locked inside the actuator. So a loss of hydraulic pressure should not affect the control unless you want to actuate the valve. Maybe closing of GCV valve happened because it is constantly moving 0.5% up and down, so it is permitting a small amount of oil to the actuator. IGV was not affected because the degree usually is stable not moving up and down. this is my interpretation of the situation happened.
Anyone can comment and clarify?