Hi everyone,

I have been working for gas turbine frame 6b, i severe some problem during start with fuel oil.

on August 2019, gas turbine are able to start with fuel oil but then trip since step synchronizing initiate. the alarm appear was "loss of flame"
after that try to start with several checking in liquid fuel distribution line, then re-start and facing the same failure.

then start using fuel gas, everything was fine. continue running on fuel gas until 2020.

on November 2020, gas turbine trip while running at base load then fuel gas pressure low-low, initiating fuel change over, then trip by "exhaust temperature high high". after that restart with fuel oil due to unavailable fuel gas, but failure to firing, there is no flame detected.

then do several checking on spark plug (good, able to sparking), flame detector (good, able to detect flame), main fuel pump/magnetic clutch (engage and spin), flow divider (good, since running pressure each line appear approx. 7~8 bar).

second time start with fuel oil,. still firing cannot succeed.

so wait for availability fuel gas, and running with it until today.

did anyone here known what is going on my fuel oil problem ?

regards,
Tresna

 

Yes. This topic has been covered many, Many, MANY times before on Control.com. Use the 'Search' feature at the top of every Control.com webpage to look for Similar threads. Also, at the bottom of every thread is a section called 'Similar threads' which lists threads an algorithm thinks might be related.

You might think some of the threads you find are not exactly related to your problem--but I assure you there are excellent troubleshooting ideas and suggestions you can use to eliminate various possibilities and work towards a resolution. Depending on the last time the unit went through a maintenance outage it's VERY possible the check valves (liquid fuel check valves; liquid fuel purge air check valves) have failed. Also, it's very possible the liquid fuel nozzles have some carbonized liquid fuel inside which make atomization difficult.

You have not told us what turbine control system is in use on the turbine.

Use the Search feature to look up previous (archived) threads. You may need to use a few different search words and/or terms, but try it. There's almost two decades of GE heavy duty gas turbine stuff on Control.com--so it's pretty certain your question has been asked and answered more than once. Maybe NOT EXACTLY the way you perceive the problem, but read a few similar threads and if you still have questions write back.

I also suggest you get out the P&IDs for the Liquid Fuel system and the Liquid Fuel Purge (or Purge) system and study them. And, then go out and find the "Tell-Tale Leakoff" (it's usually under the walkway on the right side of the turbine compartment) and then have someone watch that when trying to transfer to liquid or start on liquid.

Finally, if you want to avoid a lot of thought and study and effort, just start pulling and testing the liquid fuel check valves (there are ten (10) of them) and the liquid fuel purge check valves (there are ten (10) of them) and make sure you have at least seven (7) or eight (8) of each of them because if they fail the testing (and it's likely at least a few will) you will need to be able to replace them. The spring-loaded, poppet-style check valves used on most GE-design Frame 6B heavy duty gas turbines are KNOWN to have a pretty high failure rate, especially on dual fuel machines which operate primarily on gas fuel and not very often on liquid fuel. Get used to it. It's an occupational hazard.

Please write back to let us know what you find.

 

Oh, and I want to add: What alarms are being annunciated when these problems occur? If it's a Mark* turbine control system, does it actually annunciate the alarm LOSS OF FLAME TRIP? Because if it doesn't, and you're just attributing the trip to loss of flame, then it's something else--and there SHOULD BE an alarm to indicate why it tripped.

If it does annunciate LOSS OF FLAME TRIP then that, too, has been covered before many, Many, MANY times on Control.com. Quickly, it means the flame was lost BEFORE any trip condition would have shut off the fuel to extinguish the flame. On liquid fuel systems, plugged filters, plugged strainers (upstream of the liquid fuel forwarding pumps), air in the liquid fuel supply piping, a non-working liquid fuel forwarding pump pressure regulator, a sticking liquid fuel bypass valve servo (they CAN'T be calibrated on a Frame 6B because the liquid fuel bypass valve DOES NOT have LVDTs), air in the liquid fuel supply piping, worn liquid fuel flow divider bearings, air in the liquid fuel supply piping, etc. Did I mention air in the liquid fuel supply piping? That's a VERY COMMON problem on dual fuel machines which don't run very often on liquid fuel. That and check valves.

So, big hints for you. Best of luck.