gas turbine frame 5 axial compressor. PLZ ANY BODY TELL ME WHAT IS PURGE AIR AND WHAT IS OPERATION OF PURGE AIR
Purge air is generally compressor discharge air used to purge lines of combustible vapors as well as to cool components. For example, CPD used to purge the gas fuel system when operating on liquid fuel, the purge air is supposed to ensure that there is no combustible gas/air mixture present in the piping being purged, and it also serves to cool the gas fuel tip(s) of the fuel nozzle(s) in the combustor.
You should be able to find a Piping Schematic (P&ID) for the Purge Air system, and some kind of system description in the Service/Operation Manual.
If you still need more information, you're going to need to provide more details about your question.
Thank you for this info.
Meanwhile, I am working on the Engineering stage of GE FRAME6B, and the Purge air line is taking on the PID to DLN Fuel gas skid. I understand the first point that it will be used to cool the fuel gas tips of the fuel gas nozzles in the combustor. BUT I will like to know if in that same line is used for purging combustible vapor?
As in the previous reply, purge air is used to push out any combustible gases (vapours) in the fuel nozzle, for cooling the fuel nozzles, AND to prevent backflow of hot combustion gases into the fuel nozzles and manifolds which can result in circulating hot combustion gases between combustors and severe damage.
Purge air, when first introduced into the gas fuel manifolds/nozzles, pushes out any remaining gas fuel (when transferring from liquid fuel to gas fuel). That's why the purge valves, VA13-n, are usually set to open relatively slowly so as not to suddenly push a lot of fuel into the combustors which can result in a load spike and an exhaust temperature spike.
Hope this helps!