Marine and land-based industrial (M & I) gas turbine engines are frequently derived from engines designed for and used in various types of aircraft. Such marine and industrial gas turbine engines are used, for example, for powering marine vessels, electrical generators, and various types of pumping and compression applications.
The parent gas turbine engine of an M & I engine is typically designed and constructed to be lightweight and to operate at minimum specific fuel consumption (SFC) in an aircraft for predetermined thermodynamic cycles of operation having predetermined ranges of air and combustion gas flowrates, temperature, and pressure in the engine. The parent, or aircraft, engine cycles are also preselected for maximizing thermal and propulsive efficiency of the engine.
Development of an aircraft gas turbine engine requires a substantial amount of design, development, and testing resulting in substantial development costs. In designing gas turbine engines for marine and industrial applications, it has proved to be more cost-effective to modify an existing aircraft gas turbine engine in the desired power class, than to design the M & I engine from the beginning. Accordingly, it is desirable to minimize the changes in the aircraft engine required for obtaining a suitable M & I engine.
One application of an M & I engine is to provide peaking power for powering an electrical generator to provide additional electrical power to a utility power grid when the utility power demands exceed on-line baseload capacity. Accordingly, the utility industry desires relatively simple and inexpensive gas turbine engines which can be brought on line quickly and then shut down quickly as required to meet the peaking requirement. One goal is to generate the required power during peaking operation as efficiently as possible for reducing kilowatt-hour costs.
One factor in obtaining relatively low kilowatt-hour cost is the development costs for providing an industrial gas turbine engine for meeting the required power demands. In order to keep development costs relatively low, the industrial gas turbine engine typically utilizes the parent aircraft gas turbine engine and makes as few changes in the design thereof as practical for obtaining the desired land-based gas turbine engine. Accordingly, the parent aircraft gas turbine engine utilized for M & I applications may be adapted specifically for particular applications, including, for example, driving an electrical generator at a synchronous speed such as 3000 rpm or 3600 rpm, for generating electricity at 50 Hertz or 60 Hertz, respectively. Since electrical power generation is desired, and in particular, for meeting peaking utility demands, maximum output shaft horsepower from the gas turbine engine is desirable for maximizing the amount of electrical power generated by the generator.