hellow

I am working on G.E frame 6 mark 5 ms6001b gas turbine.

The gas turbine was running on fuel gas at full load 30 mw. All the reading parameters like exhaust was 500 deg c. ttxsp1, ttxsp2, ttxsp3 were 32 deg c approx, ambient temp 20 deg c. which were normal in such working conditions.

As we transferred the fuel from gas to distillate. After nearly four hours we found the gas manifold (common to all nozzles) was red hot. At the same time all the reading parameters like exhaust and spread where found normal approx same as explained above. The flow divider was showing distillate flow at 32 bars to all 10 nozzles.

what can be the reason for such red hot appearance of the gas manifold? due to hot gas return from combustion chamber?

please do mention if any further explanation required
regards
suhail

 

Low or no purge air?

 

hello

gas fuel line has leakage. the hot gas then goes into the gas pipe.

 

G.E frame 6 ms6001b at our station has a draw back it does not have purging for the gas manifold (gas lines).

 

Dear Suhail,

<The flow divider was showing distillate flow at 32 bars to all 10 nozzles>>

Are you sure 32 bar to each nozzles?

Normally distillate inlet pressure will be 5 to 6 bar and at flow divider it'll around 7-8 bar. What is the CPD? and wheelspace temperature?

Take care
G.Rajesh

 

Hellow rajesh,

The flow divider was showing 32 bar to all the 10 nozzles because the turbine was on full load that is 30 mw. The flow divider pressure on fsnl is 12 bar to all nozzles. The inlet to the flow divider is the outlet of high pressure fuel oil pump (screw type) (max 40 bars) driven by accessory gear. this pump output is regulated by fuel control valve as required. so the pressure at the flow divider cannot be 7 or 8 bar at full load.

The cpd was 10 bars.

 

Suhail,

How are you relating liquid fuel pressure to back-flow through the gas fuel nozzles and manifold?

This must be a pretty old machine, even with a Mark VI, because most dual-fuel GE-design heavy duty gas turbines built since the mid-1980's were equipped with gas fuel nozzle purge systems just to prevent this type of occurrence.

What were the exhaust temperature spreads on the unit when this even occurred?

 

Dear csa
Thanks for giving your views. Was waiting 4 your reply.

By the back pressure i meant the return of hot gases from the combustion chamber to gas manifold through the nozzles. (Correct me if wrong)

The turbine i am talking about is mark v . Dont knw the year of make.will let u knw in my next post. We also have ms9001e frame 9 mark v 100 mw gas turbine which is equipped with gas purging.

The spreads were as follow
Ttxspl 165 deg c
Ttxsp1 32 deg c
Ttxsp2 29 deg c
Ttxsp3 27 deg c
Ttxm 504 deg c
Ttrx 560 deg c