Our 9E DLN1 unit trips at PMX to LL xfer during almost every shutdown. We have CTXF thermocouples installed in crossfire tubes and a logic that trips the unit if one of them senses temperature higher than CTDA + 32 DegC for about a minute, or if one of them senses overranged temperature - above value MKV able to read and goes to negative, - for 5 seconds. All trip come from the latest. Temperatures start rising the same second with reignition signal and every time between different combustors. Lately we started experience also a problem at transfer from LL to PMX state and switching IBH ON helps, but we noticed it happen mostly after a run on liquid fuel, even though we run in LL mode for 30 min on gas to purge liquid fuel leftovers.
Multiple checks were carried out - all gas valves, purge valves, tightness tests, check valves, tubing connections, borescopes... All good.
Two thing must have been added before I'm switching to "waiting for an answer" mode: 1) We have a very high temperature in the turbine room, about 130-150 DegC, and we've found turbine casing leaking ( In other identical unit we have exactly the same problem but never a problem with DLN transfers ). 2) The unit underwent a Major two years ago and a whole new set of combustors, liners, nozzles was installed. Since then this problem started to appear, at first very rare so no one have connected this fact to the Major Overhaul, and got worse with a time.
After having performed same checks with minimum results ( sometimes we do find stuck check valves ) we strongly think that this unstalled hardware is the cause of a problem, although mechanical engeneering department insists that ist exactly the same hardware as before.
Will appreciate any thoughts and suggestions written.
Multiple checks were carried out - all gas valves, purge valves, tightness tests, check valves, tubing connections, borescopes... All good.
Two thing must have been added before I'm switching to "waiting for an answer" mode: 1) We have a very high temperature in the turbine room, about 130-150 DegC, and we've found turbine casing leaking ( In other identical unit we have exactly the same problem but never a problem with DLN transfers ). 2) The unit underwent a Major two years ago and a whole new set of combustors, liners, nozzles was installed. Since then this problem started to appear, at first very rare so no one have connected this fact to the Major Overhaul, and got worse with a time.
After having performed same checks with minimum results ( sometimes we do find stuck check valves ) we strongly think that this unstalled hardware is the cause of a problem, although mechanical engeneering department insists that ist exactly the same hardware as before.
Will appreciate any thoughts and suggestions written.