Gas turbine in FSNL during steam piping cleaning 1

[dario1973]

Dear all,

please help me to find a solution to this question.
If We are in the steam blowing phase of BOP and HRSG
and there's no availability of the electrical substation,
it's possible to run the GT in FSNL during several
blowing? Tha gas turbine is a V94.3A2. There's some
problem with the LCI/static starter or somethink else?
Thanks in advance, Dario

 

[GTstartup]

Do you have another source of power for the starting device and the GT auxiliaries? If not, you're out of luck. If yes, then I don't see a problem.

 

[dario1973]

I've another source of power from another existing substation. Thanks a lot.
I have another question regarding the exhaust gas at the outlet of the gas turbine (V94.3A2): with GT26 and MS9001 FA there are no problem because the outlet temperature is high then the V94.3A2' one (in base load condition we have 580°C for the V94.3A2 and more than 620°C for the other turbines). May be that with V94.3A2 there are non condition in terms of temperature to performe the steam blowing (depending from tha specification of the blowing contractor). Have You any experience regarding this problem? The HRSG is STF with three pressure level + RH (performance with 100% load --> LP steam with T=249°C, p=3.95 barg and F=44.3 ton/h; IP steam with T=307.5°C, p=36 barg and F=51.4 ton/h; RH steam with T=550°C, p=34.5 barg, F=301.9 ton/h; HP steam with T=545°C; p=119.8 barg; F=267.6 barg).

Thanks in advance.

 

[GTstartup]

If I understand your question correctly, you are saying that the Siemens unit's exhaust temperature is 40 deg C less than the ABB (Alstom)and GE Unit's. And maybe this is not suitable for steam blow.

Not all units have the same exhaust temp at base load (or any load). If the V94 has variable inlet vanes you could throttle them to bring the exhaust temp up. Otherwise it may just take slightly longer for the V94 to make required steam temp.

Besides, 40C delta doesn't seem that much of a big deal to me. And anyway how are you going to get to base load with no substation available to connect to the grid?

 

[dario1973]

No, I'm not going to get base load because I haven't the availability of the substation. My doubt was realted to the fact that probably if in condition of base load the flue gas discharge of the GT is lower than the others GT and in FSNL I could have the same gap or higher. But, thinking to Your advise I can close the IGV to increase the exhaust temperature and stay with this angle the required time to reach the steam condition. May be it's reasonable reach the goal for HP and LP circuits but I have some doubt for the IP circuit that is the big one. But may be that I have the substation ready when I blow the IP steam piping.

Thanks.

 

[GTstartup]

No Problem Dario.

One piece of advice. Check your logic to mak sure that the IGVs can be manually operated at FSNL. Some units have limitations that only allow the manual operation of IGV at higher loads. If this is the case you may have to change your logic. Consult with the OEM before doing this

 

[dario1973]

I'll follow Your advise.
Thanks a lot and see You soon.

Bye, Dario

 

[tommy75]

Dario,

I take it you do not have Aux. Duct burners in the HRSG itself you can bring online? If you do that should solve your probelm for temp during blows.

 

[dario1973]

Unfortunally I haven'this system but
I have had from the contractor the confirmation about
the possibility to blow the HP and LP system. They have some doubt about the IP system.

Bye

 

[tommy75]

Dario,

I'm not sure where you are but there are a few companies that can bring in an auxillary boiler you could tie in to your IP steam circuit to reach your target blows if your substaion is not available when you are ready to do so. They do deliver worldwide but if cost is a factor that could truely come into play. But the units are more than sufficient for the spec's you listed above.

Just another option if you get into a bind.