Turbine Tip No. 11 from the PAL solutions library applies to General Electric package power plants (PPP), including the following: Model Series 5001, 6001, and 7001.
GE installed heaters in the accessory and turbine compartments (combustion-chamber area) to maintain their space temperatures at levels that promoted good combustion on initial firing.
One experience to share: A client with two MS5001N gas turbines for emergency and peak-power generation called a couple of years ago to say both units were having difficulty starting and firing in the dead of winter (February, minus 18F—to be exact). Once onsite I opened the accessory compartment on one unit and found wires hanging from a space heater (Fig 11-1). I was told that the heaters in the combustion compartment had failed because of the too- hot environment so all heaters were disconnected, staff believing they were “unnecessary.”
Space heaters are not there for operator comfort, I reminded plant personnel: They are installed to assure that the on-base fuel and fuel-system components are kept relatively warm. Lines from the LP fuel filter, fuel stop valve, fuel pump, HP filter, and flow-divider elements (Fig 11-2) must be warm to function as designers intended. Especially important is to keep warm the 10 small-diameter fuel lines running from the flow divider under the compressor inlet plenum to the combustors.
Why this is necessary: The first firing attempt involves approximately three gallons of fuel— oil already on the accessory base. If this first attempt fails, oil must come from the fuel forwarding skid, which is off-base and often in open air or an unheated enclosure. Most fuel systems have heat tracing for the buried fuel line to the gas-turbine base, but not all do.
Proper compartment sealing also is important, to retain heat produced by the space heaters. Doors and seals also should be kept in good condition to maintain effective fire protection (see Turbine Tip 10, above).
To sum up: Space heaters in the accessory and turbine compartments must be kept operational, particularly in northern US and Canadian locations. This way, when the ambient temperature drops below freezing, you can be confident that the fuel already on-base will be prepared to ignite on the first firing attempt.
