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Maximum Gas Pressure Inlet for Frame 9E GTG
How much we can increase the pressure inlet for servo valve


in my company we have a gas station. i want to increase the pressure outlet from this station, but i don't know how much we can increase this pressure without cause a problem for gtg.
in my company we have two type frame9e markv. one type is: non-dln another type is DLN.

I searching in my document there isn't any thing about that, just we have a high pressure value. i don know it's correct we haven't any pressure higher than value.

thanks for reply very much

You should find the maximum allowable gas fuel supply pressure listed in Sect. 05.02.nn of the Control Specifications provided with each of the two GTGs. ('nn' refers to a sub-sub-section number which was not always the same for every unit--though the gas fuel section was always located in Sect. 05.02.)

I believe you will find it is NOT the same for the two GTGs--the one with the conventional combustors will likely be somewhere around 275 psig, and the one with DLN-I combustors will usually be slightly higher. There will usually be a range of allowable minimum- and maximum pressure (such as 275 psig, +/-15 psig).

The risk in increasing the gas fuel supply pressure is two-fold. First, you run the risk if exceeding the piping and flange ratings which represents a safety risk if they fail. (Flange ratings are usually stamped on the edges of the flanges.) AND, control valves have maximum allowable pressure ratings, also. (Many of the combined SRV/GCV assemblies used for GE-design heavy duty gas turbines of all Frame sizes had maximum allowable working pressures of 300 psig. Early turbines with DLN-I used these valves and the desired supply pressure was raised to 310-325 psig, but then GE went to the independent gas valve arrangement, with individual SRV and gas control valves to supply the primary, secondary and transfer manifolds/nozzles (the transfer systems were not used on some units).)

Second, by increasing the gas fuel supply pressure you will be forcing the SRV to close more to maintain the required P2 pressure (gas fuel intervalve pressure), which is not usually such a problem when loaded, but could be a problem during firing if the supply pressure is excessive.

I don't recall ever seeing the maximum allowable gas fuel supply pressure for any GE-design Frame 9E gas turbine to be more than 325 psig, but I haven't seen every site/turbine ever built. It could be different if using low-BTU fuels, but I would still suspect that piping/flange/valve ratings would represent the absolute maximum allowable pressure--which is NOT NECESSARILY the maximum allowable pressure for proper starting and operation.

Again, I caution you to refer to the GE-supplied Control Specification drawing's appropriate section (one of the sections in 05.02--it wasn't always the same section number, but I believe it was called 'Expected Fuel Characteristics). If you can't find the Control Specifications for the two machines, I highly recommend contacting GE for assistance with this endeavour to prevent causing undesirable knock-on effects, or, worse, damage to piping/components.

Hope this helps! Please write back to let us know what you discover.

By the way, why do you believe it's necessary to increase the gas fuel supply pressure?