Results of Losing Second Liquid Fuel When Gas Turbine Operates on Dual Fuel


Thread Starter


Hi every one,

I work in a plant with GT frame 9E simple cycle with two fuels (crude oil and distillate), and I have the following question:

what happen when the GT operates on crude oil (HFO) and the second Liquid fuel (LDO) is lost due to faults in the distillate pumps?

your first big problem: if you are running on HFO and your distillate has failed, is when you need to shut down. The machine should switch to distillate during the shut down to flush the HFO out of the system. If this doesn't happen you are going to have static HFO sitting in your fuel system which is going to cool and at least get sticky if not solidify. The answer is to get your distillate system working again before you shut-down or at worst, within a short time after you shut-down so you can flush your fuel system.
You mean that the machine will not take any action if I lost the distillate fuel when it running on HFO????
Yes, exactly.

Machines which run on HFO must almost ALWAYS be started and stopped on LDO for the reasons Glenmaorangie listed. HFO can rarely be used for starting because it is difficult to atomize at ambient temperatures and must be heated to improve atomization--which is difficult at low flow-rates during startup and acceleration. So, most turbines must be started on LDO and shifted to HFO at FSNL or some light load when the flow-rate is higher and can be more easily heated for better atomization.

Because HFO is usually very thick and viscous at ambient temperatures almost all turbines running on HFO are required to switch to LDO at se light load during a normal STOP in order to allow LDO to purge the HFO from the fuel lines and fuel nozzles. If a turbine trips while running on HFO it's very important to take steps to purge the HFO from the fuel lines and -nozzles before it cools in them making starting difficult if not impossible. Some turbines have specia, manual three-way valves in the fuel lines to allow manual purging if necessary. Otherwise, it's usually necessary to disassemble the fuel lines and -nozzles to clean the HFO prior to re-starting on LDO.

The control system is not typically programmed to take any action in the event LDO is unavailable when running on can't initiate a STOP because it's supposed to stop on LDO. It's incumbent on the operations and maintenance to restore LDO availability as quickly as possible to prevent a trip which would result in the fuel lines and -nozzles being full of HFO which could cool and cause problems.

Even if the control initiated a controlled STOP while running on HFO there's still the need to purge the HFO prior to starting again--again because HFO doesn't atomize well at low flow-rates and/or low temperatures.

There are some very light crudes which don't require much heating for atomization but you haven't told us much about the HFO (crude) at your site.

Hope this helps!
Ok, thanks for your reply, I am also think that there are no action from the machine till the problem of LDO fuel is solved.