our unit is GE frame 7E mark v controller capacity 60MW

I would like to ask about change over from Gas firing to light fuel oil mode before unit reaches full speed no load. is it going to trip? or accept the change over.

because we have tried that two times and unit tripped.

thanks,
Ayed

 

I think your question might better be phrased is should it trip rather than is it going to trip, seeing as you have tried it twice and it tripped both times.

Have you asked this question of the people that sold it to you?

What does the manual say about switching fuels like this?

 

Ayed

as Bob says this question would be best answered by the packager, or by your O+M manual, or lastly by studying your CSP.

Typically fuel change-over is not allowed during startup, but obviously your unit is not "typical". Most units I have seen allow you to make a fuel selection before you select start and then not again until the unit is at full speed no load or above a certain load, depending on the type of fuel.

Changing fuel during startup is never a good idea on any machine. During this period of time the compressor is typically nearest its margin for stall and changing fuel during this time could cause a blowback condition. I am not sure why "logic" allowed you to try and make a fuel selection change. But I am also curious if your plant has a standard operating procedure that defines what is to be done, and what should not be done during a startup. But in your case it sounds like something needs some work.

 

Fuel changeover could not be successfully before the unit is at least at FSNL due to limitation from the compressor. BTW i do not see any reason for the changeover to be done when the unit is accelerating as the selection could be done earlier or later. My machine (GE F9E) is recommended to have changeover at atleast 30MW and above but I have tried and successfully made the changeover when the unit is at FSNL (just for testing purpose).

Have you conducted similar changeover in the past and successful?
You may want to list the alarms announciated when your unit tripped for further analysis.

 

dear;

my question was very clear.
does the unit change over from gas to LFO before it reaches its FSNL. i tried that only in emergency.

i did not any action except this way.

 

dear;

A typically--and properly--configured Speedtronic turbine control panel would <b>NOT</b> accept a command to change fuels below 95% speed. Even in an "emergency."

Unless some logic signal was forced to bypass the normal logic.

So, unless you have a very atypical Speedtronic something doesn't compute.