Hi everyone!... I hope this beginning of the year is being good for all of you.
I return to the forum to comment on another failure occurring on the GT MS6001B with MK V.
The thing is that due to a problem with the gas supply in the plant, it was decided to startthe turbine with diesel oil (distillate), the machine had not run with this fuel in about 2 years.
When we started with the first attempt, there was a trip due to loss of flame. On the second attempt, it ignited, but there was an exhaust overtemperature trip.
We assumed that maybe was the MOOG servo valve with a problem (2 years without moving), so we changed it, did another test, but the same thing happened. We check filters, both diesel and hydraulic oil, all good. We decided to check the flow divider.
We open its inspection covers, and with a flat screwdriver we try to turn the shaft (it should move without much problem), but we find it heavy, impossible to move, that is already a problem, we must replace or repair the flow divider.
The thing is that after solving the problems with the gas supply to the turbine, we decided to do a gas start, and to our surprise, the same thing happened, overtemperature trip in the exhaust.
The strange thing is that only a couple of temperatures are those that rise with great speed, immediately when the chambers are fired (3 actually, numbers 14, 15 and 16) corresponding to the combustion chambers numbers 8, 9 and 10, the others rise also, but not so fast. At the time of ignition, a strange noise is heard, apparently coming from the combustion chambers, like a loud air blowing or air restriction... Also, the pressure gauge for gas after the GCV stays in 0 bar (even though both valves move, and the combustion chambers are ignited).
Both valves move well giving them command in manual mode.
We tought that maybe some fuel nozzles were blocked, thus the gas pressure was entering chambers 8,9 and 10 with more pressure than normal.
We removed the nozzles for chambers N°2 and N°3, but they were clean... then we removed all check valves for liquid fuel (air and fuel) thinking that maybe some were stuck in open position, perhaps creating a problem with pressures inside the nozzles or with the atomizing air.
Effectively, some were stuck in the open position, specially the air ones, full of fuel, and you could blow one way or the other, so we clean them until they were normalized.
We did another gas start, thinking this discovery was the problem, but the problem continued.
We also simulate temperatures with a calibrator, directly to the TBQB card in core <R> (at the points of the temperatures that rise faster) and the inputs are perfectly fine. In turn, just to rule out, we measure one of those thermocouples with the same calibrator, at the moment of turning on, and it behaves in the same way as seen on the screen, it rises steeply, in ranges of 100 ° C per second.
It would seem that these temperatures, instead of being in contact with combustion gas, were in contact with a live flame.
We are thinking of doing a boroscopy, to see for any irregularity inside the chamber, the transition piece, or the exhaust.
Do you have an idea, or have you ever had a similar problem?
Thanks in advance!
.
I return to the forum to comment on another failure occurring on the GT MS6001B with MK V.
The thing is that due to a problem with the gas supply in the plant, it was decided to startthe turbine with diesel oil (distillate), the machine had not run with this fuel in about 2 years.
When we started with the first attempt, there was a trip due to loss of flame. On the second attempt, it ignited, but there was an exhaust overtemperature trip.
We assumed that maybe was the MOOG servo valve with a problem (2 years without moving), so we changed it, did another test, but the same thing happened. We check filters, both diesel and hydraulic oil, all good. We decided to check the flow divider.
We open its inspection covers, and with a flat screwdriver we try to turn the shaft (it should move without much problem), but we find it heavy, impossible to move, that is already a problem, we must replace or repair the flow divider.
The thing is that after solving the problems with the gas supply to the turbine, we decided to do a gas start, and to our surprise, the same thing happened, overtemperature trip in the exhaust.
The strange thing is that only a couple of temperatures are those that rise with great speed, immediately when the chambers are fired (3 actually, numbers 14, 15 and 16) corresponding to the combustion chambers numbers 8, 9 and 10, the others rise also, but not so fast. At the time of ignition, a strange noise is heard, apparently coming from the combustion chambers, like a loud air blowing or air restriction... Also, the pressure gauge for gas after the GCV stays in 0 bar (even though both valves move, and the combustion chambers are ignited).
Both valves move well giving them command in manual mode.
We tought that maybe some fuel nozzles were blocked, thus the gas pressure was entering chambers 8,9 and 10 with more pressure than normal.
We removed the nozzles for chambers N°2 and N°3, but they were clean... then we removed all check valves for liquid fuel (air and fuel) thinking that maybe some were stuck in open position, perhaps creating a problem with pressures inside the nozzles or with the atomizing air.
Effectively, some were stuck in the open position, specially the air ones, full of fuel, and you could blow one way or the other, so we clean them until they were normalized.
We did another gas start, thinking this discovery was the problem, but the problem continued.
We also simulate temperatures with a calibrator, directly to the TBQB card in core <R> (at the points of the temperatures that rise faster) and the inputs are perfectly fine. In turn, just to rule out, we measure one of those thermocouples with the same calibrator, at the moment of turning on, and it behaves in the same way as seen on the screen, it rises steeply, in ranges of 100 ° C per second.
It would seem that these temperatures, instead of being in contact with combustion gas, were in contact with a live flame.
We are thinking of doing a boroscopy, to see for any irregularity inside the chamber, the transition piece, or the exhaust.
Do you have an idea, or have you ever had a similar problem?
Thanks in advance!
.