My Project- GE FR9,Fuel Purge Check Valves relocation

This is the original position of the check valves for this dual fuel nozzles,
the larger one is for distilate fuel and the smaller is for purge air.
The purge air tubing is connected from the check valve to a purge air ring(manifold)
and further connected to a solenoid controlled valve which will open to supply purge air when the GT is running on gas and close when it is running on distilate.
The purge air is tap from the atomizing air supply line.

The problem is with the position of the purge check valve where the GT normally runs on gas and only switches to distilate whenever there is a problem with gas supply.
With the GT running on gas the temperature of the check valves could be above 100 deg c and on normal running trial we did, the seals only lasted a few hours on gas and starts to leak after a fuel change over.

The problem could be reduce if we have a very big cooling fan for the turbine compartment
but i think that is someone else job so we decided to bring the check valves away to some where near the solenoid controlled valve by adding a new compact manifold.


The old position of check valves.


The old purge air tubing is connected to the pipe around the CDC
(compressor discharged casing) compared to the new one
which is run right up to the new compact manifold
after the solenoid controlled valve.




The original elbow piping the purge air to the ring.

The solenoid controlled valve.

The new compact purge air manifold.

The new tubing for the purge air to the manifold.

During CI,HGPI and MI the tubings from the elbow (in front of chamber no:7)

to the unions above the lube oil drains have to be removed

so that the combustion chamber doors can be opened and parts removed.

Other tubings following the casing need not be removed except the short piece to the fuel nozzle.

The tubing should be marked and removed by opening the top nut of the elbow

and pushing the tubing down and then opening the nut at the union above the lube oil drain

before the tubing is removed.

During inspections the tubing shoud be checked for chokage and cleaned before reinstallation.

This blockage could be due to insufficient atomizing air pressure where the purge air is tapped,

therefore the atomizing air compressors,shaft or motor driven should be check and service frequently maybe once a year preferably during an inspection.

Check valves should also be check for cracking pressure and most important its non-return sealing so that it is not passing.

Repair kits for the check valves should be made available during the inspection.

These unions above aren't the best choice,

should have used other methods like this one below.

A hole is cut for the 14 tubings to come out and later seal with thin metal plates.

The check valves in 2 levels,

7 on top and another 7 at the bottom.

The new compact manifold made of SS replaced the elbow

and the other end is also blanked off.

A drain valve for every check valve to check if it is passing.

A safety leak tray is added for this GT in Pahlawan Power

which is done in 1997 when it was still called Tanjung Kling Power Station.

And leakages if any is piped to the drain line.

This one in Putrajaya, the drain valve is further piped to a position outside the enclosure.

Tubings exits here.

Each valve is tagged with a number which corresponds to the check valve

and fuel nozzle it came from.

The valves are normally closed and is open only to determine

which check valve is leaking during operations on distilate.

These valves must always be in a closed position.

All together 4 GTs have been running on this mode.

Operator should be aware that there will be a slight spike in exhaust temperature

during change over from distilate to gas because of the burning of

leftover distilate in the tubing that are being purged out.