Hello dear experts, I bring you a question about a MS6001B with TMR control, available with diesel and gas ignition.

This gas turbine was originally purchased with only diesel firing, and the modification for gas firing was done a few years later (by GE obviously).

The question is, every time the turbine starts with gas ignition, diesel forwarding pump 88FD1 also starts, the same for L20CF1X solenoid which is also energized, magnetizing the coupling and making the high pressure pump for diesel move along with the accessory gear drive.
Is this ok, or did GE forget to modify this logic?.

Thanks in advance!

 

It’s not okay, and both the requisition engineer and the commissioning person didn’t catch the mistake. The requisition engineer is the “factory” person who makes the control sequence program modifications and I/O modifications and then should test the software before releasing it and sending it to the site. The commissioning person should be on the lookout for any incorrect sequence/logic and make the appropriate changes to protect the equipment. Running the fuel forwarding pump with no flow heats up the fuel in the pump casing. Running the high pressure liquid fuel pump with no flow does the same thing—heats up the fuel that is in the pump casing and recirculates to the pump inlet through the liquid fuel bypass valve.

One HOPES the liquid fuel stop valve, operated by 20FL-1 is not open during ignition….

You would be wise to have the modifications made sooner rather than later. The site has been lucky up to this point; don’t push your luck.

 

Hi wtf? thanks for your reply.

What I should mention is that if there is a flow, the liquid fuel pressure reaches the filters in the GT with 6 bar, and goes through the on-off valve (I don't remember the device name), then it recirculates through the high pressure pump. and through the control valve (or bypass, it's the MOOG brand right?), without going to the flow divider.
Yesterday I measured the temperature in the high pressure pump and it reached 75°C with 35 MW.

A couple of years ago I consulted a person who had been working on this site for many years, he told me that the reason why the L20CF1X solenoid was also energized and liquid fuel was recirculating even in gas firing, was because you could make the change from gas to liquid fuel while running. .. but I have doubts if it will be so, hence the question.

So, long story short, on a gas fuel start, the liquid fuel forwarding pump shouldn't start, nor the L20CF1X energize, right?

Thanks in advance again.

 

Well, …, that’s one means of keeping the air purged out of the liquid fuel system—that I’ve never heard of. Yes, the liquid fuel bypass valve acts to recirculate liquid fuel from the discharge of the positive displacement high pressure liquid fuel pump back to the suction (inlet) of the high pressure liquid fuel pump—but it’s not meant to do that continuously while the unit is operating on gas liquid fuel. Unless the high pressure liquid fuel pump on that machine is different from the ones used on almost every other GE-design heavy duty gas turbine. And if the unit came from GE in Belfort, France, it could be….

During a typical transfer from gas to liquid fuel there is a period of time between when the transfer is initiated (either manually or automatically) and when the liquid fuel bypass valve (which is the liquid fuel control valve) starts to close and send fuel to the fuel nozzles. That period of time is necessary to shot off the liquid fuel purge system and start the liquid fuel forwarding pump and open the liquid fuel forwarding stop valve and the liquid fuel stop valve—pressurizing the system, but pressurization does not remove air.

If the liquid fuel system is always pressurized—even when the unit is running on gas fuel—it’s conceivable the chances for air to get into the liquid fuel system are lower. But pressurizing the liquid fuel system like this runs the risk of overheating the liquid fuel in the forwarding and high pressure liquid fuel pumps.It’s possible the high pressure liquid fuel pump is sized and constructed to reduce the possibility of damage under these conditions, but without much more information that’s impossible to say with any degree of certainty. AND, you said the unit was originally commissioned with liquid fuel only, so unless the high pressure liquid fuel pump was changed during the addition of gas fuel that’s not likely.

I suppose one could argue if the machine has been running this long in this configuration it’s reasonable to assume it will continue to operate without problems—but the period it will remain in good condition is in question without knowing a lot more about the equipment.

I can only talk to typical configuration and operating principles—I have never encountered this configuration. I HAVE NOT seen all configurations so i can’t speak to every one. Thank you for the additional information and I hope I haven’t caused too much confusion.