K
Dear Gents,
We are having GE frame 7FA DLN 2.6 Gas turbines, 99% of the time we are running on base load
We are experiencing at typical problem, the scenario is like this:
Both GT were running on base load. in the morning shift we received a call from Fuel gas supplier (natural gas) that are performing fuel gas line scrapping activity. however they opened the blowdown at their end to remove any moisture and any contaminants in the fuel gas.
Scrapping activity was going on since morning shift.
in the evening shift suddenly we observed step load change from 140 MW to 155 MW in 10seconds!!!
we have observed increased in machine vibration, increased NOX values, change in fuel gas composition, flame intensities increased from 65% to 104 %, change in spread values
Please find the below parameters
Changes in fuel gas composition were noticed and major changes were occurred in Methane & Ethane composition. Both compositions were out of ECA limit (Methane- 76.4% & Ethane 11.6%)
Methane - 90% to 60%
Ethane - 3.8% to 33%
Changes in vibration profile and GT flame intensity were also observed Under normal condition
GT #1/2 vibration (max) - 2.4/3.2 mm/sec
During the sales gas disturbance
GT #1/2 vibration (max) - 7/11 mm/sec
Normal condition flame intensity
GT#1/2 flame intensity (max) –65 to 80%
During disturbance
GT#1/2 flame intensity (max)- 103-104%
Changes in GT Nox Emissions was noticed
Normal condition
GT1# 12 PPM, GT#02 15 PPM
during disturbance
GT#01 69.5 PPM, GT#02 74.8 PPM
1. we have moisture separator at battery limit to remove any moisture & dirt from fuel gas, moisture separator filter DP found increased from 0.4 Bard to 0.7 Bard
2. There was no change observed in fuel gas duplex strainer dp (upstream of SRV)
3. After the disturbance all parameters came to normal except the Nox values. it is still remaining on higher side, CO and O2 values also became normal (CO# 13 PPM, O2# 12.2 %)
4.GT#01 Spread values became normal (SP1# 35, SP2# 33, SP3# 40)
5. GT#02 spread in fact improved!!!! before the disturbance SP1# 52, SP2# 46, SP3# 45. after disturbance SP1# 43, SP2# 35, SP3# 35
6. Vibration also became normal
7. there was no black smoke observed from chimney,
8. Online NOx analyzer, CO analyzer & O2 analyzer values compared with portable analyzer and both values are matching
I have given suggestion to reduce the GT load below 90 M (where mode changes from 6Q to mode 5Q) and raise again and observed the Nox values whether there is a change or not.
Can you please give us your expert advice on above subject?
Appreciate your help in this regard
Regards
KKK
We are having GE frame 7FA DLN 2.6 Gas turbines, 99% of the time we are running on base load
We are experiencing at typical problem, the scenario is like this:
Both GT were running on base load. in the morning shift we received a call from Fuel gas supplier (natural gas) that are performing fuel gas line scrapping activity. however they opened the blowdown at their end to remove any moisture and any contaminants in the fuel gas.
Scrapping activity was going on since morning shift.
in the evening shift suddenly we observed step load change from 140 MW to 155 MW in 10seconds!!!
we have observed increased in machine vibration, increased NOX values, change in fuel gas composition, flame intensities increased from 65% to 104 %, change in spread values
Please find the below parameters
Changes in fuel gas composition were noticed and major changes were occurred in Methane & Ethane composition. Both compositions were out of ECA limit (Methane- 76.4% & Ethane 11.6%)
Methane - 90% to 60%
Ethane - 3.8% to 33%
Changes in vibration profile and GT flame intensity were also observed Under normal condition
GT #1/2 vibration (max) - 2.4/3.2 mm/sec
During the sales gas disturbance
GT #1/2 vibration (max) - 7/11 mm/sec
Normal condition flame intensity
GT#1/2 flame intensity (max) –65 to 80%
During disturbance
GT#1/2 flame intensity (max)- 103-104%
Changes in GT Nox Emissions was noticed
Normal condition
GT1# 12 PPM, GT#02 15 PPM
during disturbance
GT#01 69.5 PPM, GT#02 74.8 PPM
1. we have moisture separator at battery limit to remove any moisture & dirt from fuel gas, moisture separator filter DP found increased from 0.4 Bard to 0.7 Bard
2. There was no change observed in fuel gas duplex strainer dp (upstream of SRV)
3. After the disturbance all parameters came to normal except the Nox values. it is still remaining on higher side, CO and O2 values also became normal (CO# 13 PPM, O2# 12.2 %)
4.GT#01 Spread values became normal (SP1# 35, SP2# 33, SP3# 40)
5. GT#02 spread in fact improved!!!! before the disturbance SP1# 52, SP2# 46, SP3# 45. after disturbance SP1# 43, SP2# 35, SP3# 35
6. Vibration also became normal
7. there was no black smoke observed from chimney,
8. Online NOx analyzer, CO analyzer & O2 analyzer values compared with portable analyzer and both values are matching
I have given suggestion to reduce the GT load below 90 M (where mode changes from 6Q to mode 5Q) and raise again and observed the Nox values whether there is a change or not.
Can you please give us your expert advice on above subject?
Appreciate your help in this regard
Regards
KKK