when turbine trips

[SZL]

Dear,

if turbine trips, Is there a chance for fuel gas ingress due to stop/ratio valve is not fully closed. To best of my knowledge if that happens there is a possibility of explosion.Also, I would like to know what the safety procedures we should take if the turbine trips to eliminate the danger of explosion. In addition, I have another concern that how can we prevent scale getting into stop/ratio valve. I think if stop/ratio valve getting scaled, the issue of fuel gas ingress into turbine will arise.

 

[ccfowler]

First, what is your fuel gas? I would expect little risk of problems if you are using a clean fuel such as commercial pipeline natural gas. If you have some problems with particulates, then installation of suitable filters would be wise.

If you have a valid worry about some sort of scaling or corrosion problems, then I presume that you are firing some sort of process generated gas. If this is the case, then you need to address those problems with filters, dryers, scrubbers, or whatever else may be necessary to get the fuel into a suitable condition for the turbine's fuel control system. If the turbine's manufacturer is not aware of the fuel composition, now would be a good time to get in contact with them and get some serious help with your problem.

Do you really have only one valve for both control and stopping flow? Normally, I would expect that there would be separate valves for control and for stopping fuel flow. In a properly designed and functioning system, the amount of fuel that would get past the stop valve following a trip should be trivial.

 

[Mililani]

There is supposed to be, often or always is a vent valve between the Speed ratio valve and the gas control valve. Look in the device summary for solenoid 20VG. When the gas system is not used this vents the inter valve area and keeps the turbine safe, keeps gas from entering the unit.

If you think your stop/speed ratio, SRV valve is leaking with the unit shutdown, with full pressure up stream of the SRV check the discharge of 20 VG for flow. Sometimes the gas control valve leaks compressor discharge or purge air into this area also.

Once again depending on your unit there is often an alarm on p2 pressure while the unit is shutdown. If P2 remains high it indicates that the stop valve is leaking or 20VG is not venting. P2 is monitored by 96FG the P2 pressure transmitter.

hope this helps