what monitoring system installed for turbine compartment internal monitoring for 9fa machine.

as we understood that GE 9fa machine turbine compartment doors are not allowed to open while machine in service due to no insulation and possibility of thermal shock on the machine.

so, I would like to aware that what monitoring system is following by other users for turbine compartment routine monitoring.

 

@kartik.shah,

The main reasons for needing to keep the turbine compartment doors closed when running are safety-related. There are a LOT of fuel manifolds and flexible fuel piping —which means MANY flanged connections which are all possible leak points. The turbine compartment vent fans primarily serve to evacuate any fuel vapors from the compartment AND to provide a measure of cooling—using ambient temperature air!—for the compartment and devices in the compartment.

In addition if a fire or high concentration of hazardous gases (fuel vapors) were to be detected in the compartment if the doors were open it would be nearly impossible to extinguish or control the fire or effectively evacuate the hazardous gases from the compartment. Having the turbine compartment door(s) open when running disturbs the air flows in the compartment and makes evacuation of hazardous gases and cooling of the compartment much less effective. During fire extinguishing agent discharge the compartment needs to effectively be sealed to prevent air (oxygen) from entering the compartment and “feeding” the fire AND to contain the extinguishing agent in the compartment to smother the fire and keep the extinguishing agent from leaking out of the compartment. Maintaining a high concentration of extinguishing agent inside the compartment for a long period of time is essential to preventing reignition of the fire.

Finally the turbine compartment is not designed for human occupation during turbine operation—if fire extinguishing agent were to be automatically discharged while a human was in the compartment it could be deadly for the human.

Preventing excessive amounts of ambient air from coming into contact with the axial compressor and turbine casings is more important when the turbine is not burning fuel (such as when it is on Cooldown mode after fired operation) to prevent uneven cooling of the compressor and turbine casings relative to the rotor temperature to prevent rubs of the blading and buckets against the casing internals which can increase internal clearances which can decrease machine performance or even damage blading and/or buckets.

The most common methods of monitoring to ensure the turbine compartment doors remain closed when they should be closed (during fired operation and cooldown) are limit switches and-or proximity switches on the doors and/or differential pressure sensors measuring the pressure difference between the inside of the compartment and the outside of the compartment. (It should be noted that some machines use a positive pressure in the turbine compartment and others a negative pressure for ventilation and evacuation, depending on prevailing philosophies at the time of design and construction; not all GE-design Frame 9F heavy duty gas turbines are the same when it comes to turbine compartment ventilation and evacuation.)

The OEM’s decision not to use insulation on the axial compressor casing and or turbine shell is strictly a matter of their philosophy and decades of experience with combustion turbines. Maintaining turbine compartment integrity (ensuring the turbine compartment doors are closed when they should be closed) has nothing to do with whether or not the machine is insulated (except during Cooldown operation as explained). Humans should never enter a machine compartment protected with fire extinguishing agent unless the automatic discharge of the agent is disabled—which it should not be during normal fired operation.

 

@WTF?

Dear,

I apricated your reply.
I would like to know that if any user are using any type of monitoring system like internal camera monitoring, liquid leak detector or turbine compartment door having view glass or likewise any other monitoring system which allows users to externally monitoring the turbine compartment without opening the doors.

 

@kartik.shah,

It was my experience (with Frame 7F GE-design heavy duty gas turbines) that the turbine compartment doors could be opened "briefly" for a visual inspection without shutting down or tripping the machine, say for periods of 30 seconds or so. There was an alarm to alert conscious operators to an open door, and the time period was adjustable.

The big requirement for ANY devices INSIDE the turbine compartment is meeting explosion-proof technical regulations, followed extremely closely by the ability to withstand the high temperatures in the turbine compartment (which are due in large part to the uninsulated design of the turbines). As an owner/operator of equipment that is not under OEM warranty or contractual service agreement any accessories such as you listed can be installed in the turbine compartment AS LONG AS THEY MEET THOSE TWO REQUIRMENTS AT A MINIMUM. The company providing the insurance for the equipment may have other requirements (or not) which must also be considered. Also, so regions of the world also have technical regulations and standards which must also be concerned when considering these types of accessories inside a compartment which may have fuel leaks (liquid and/or gaseous).

I have seen special fire detection cameras installed in turbine compartments, as part of meeting Customer AND local technical regulations and standards. But, those are not video cameras they detect fire using different methods than a typical video camera, and I would suspect any video camera being used to detect problems and leaks in a turbine compartment would likely want to have pan/tilt/zoom capability, and that might be very difficult to find in an explosion-proof camera or even mounted inside a ventilated, explosion-proof enclosure.

Windows in doors of a turbine compartment would probably need to be capable of withstanding some blast forces, and, again, there might be local/regional technical regulations and standards which would have to be considered.

When I wrote the turbine compartment is not designed for human occupation that did not mean that the compartment doors couldn't be opened momentarily for a quick visual inspection, even taking a single step inside the lower compartment area or the grating in an upper compartment level to have a look around. But for more than 30 seconds or so, it would not be a place where someone would or should be other than for a quick look.

 

Thank you for your reply.

As I understood that no user have such monitoring and OEM also not provided such monitoring yet.

 

@kartik.shah,

A better place to ask this question would be in one of the GE F-class users groups. If you "own" a machine or have the owner's permission you can join a user's groups and get access to forums and information.

No; I don't have a URL, but a good World Wide Web search should easily yield one, or more.

I have no personal knowledge of this type of "remote" turbine compartment monitoring, but that DOES NOT mean there aren't site(s) doing this as we write.

 

Sure, I will and thanks for your concern of sharing the information.
It was to know here that any user having such situation or not.

 

@kartik.shah,

There may be users here with knowledge or experience; they may not have read your thread yet.

 

Ok, if so, we may get their experience may be later.

 

what monitoring system installed for turbine compartment internal monitoring for 9fa machine.

as we understood that GE 9fa machine turbine compartment doors are not allowed to open while machine in service due to no insulation and possibility of thermal shock on the machine.

so, I would like to aware that what monitoring system is following by other users for turbine compartment routine monitoring.

Hi @kartik.shah , what kind of monitoring you precisely looking at and what objective you are looking for opening the compartment door.. In our machine 7FA, compartment monitoring only comprise of Hazardous gas detector for monitoring any gas leak occurrences, Temperature TC and switches for compartment high temperature monitoring incase exceeded on the compartment temp operating limit, a small tempered glass door just to peak what going on inside but not a big help to see what inside, the compartment is dark while machine is running . Door limit switches for open door monitoring as well for pre startup check permissive While machine is running, it is not advisable to open unless it is emergency to do so, as you said thermal shock to machine, drop of compartment pressure for cooling as such, . The inside compartment temperature is to hot to handle. Not recommended to open while machine is running.

 

Hi @kartik.shah , what kind of monitoring you precisely looking at and what objective you are looking for opening the compartment door.. In our machine 7FA, compartment monitoring only comprise of Hazardous gas detector for monitoring any gas leak occurrences, Temperature TC and switches for compartment high temperature monitoring incase exceeded on the compartment temp operating limit, a small tempered glass door just to peak what going on inside but not a big help to see what inside, the compartment is dark while machine is running . Door limit switches for open door monitoring as well for pre startup check permissive While machine is running, it is not advisable to open unless it is emergency to do so, as you said thermal shock to machine, drop of compartment pressure for cooling as such, . The inside compartment temperature is to hot to handle. Not recommended to open while machine is running.

Dear,

Apricated your respond for the discussion in the case.

Also, accept my delayed respond due to time constraint.

we had a issue of the IGV hyd oil leak which is inside the tbn compt and was unable to notice and due to that oil lvl drop significant and Luckly it was finally noticed due to some oil trace out of tbn compt and unit was immediate shutdown to check inside tbn compt. so for such criteria i have raised the case for monitoring inside tbn compt. please note that in some other units they provide view glass and for some case i heard that thermal camera also can be installed. so was eager to know if any user had same experience and would like to share which can help in such likewise cases.


Thanks,