Page 345 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer
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Be st Practice 6 .1           Gas Turbine Best Practices























                       Fig 6.1.3   Gas turbine vs. automotive engine (Courtesy of Dresser-Rand)

























       Fig 6.1.4   Building a gas turbine



       power. This is because the air compressor typically requires two  Classification by design type
       thirds of the produced power.
                                                            Figure 6.1.7 presents the two types of industrial gas turbine. The
                                                            older type was grass roots industrial; that is, it was never built to
       History of gas turbine development                   function as an aircraft engine. The more modern approach (late
                                                            1960s) is the aero-derivative influenced industrial gas turbine.
       A brief history of gas turbine development is presented in  This design evolved from the aircraft industry, and is lighter in
       Figure 6.1.6. Gas turbines were initially used in the early 1940s  weight. Maintenance is easier than the grass roots industrial
       for military purposes. In the 1950s, gas turbines first entered  type, since components are modularized and are changed out as
       mechanical service applications. Since gas turbines are pro-  opposed to the individual parts in the grass roots industrial. Both
       duction type equipment and not custom designed, we usually  industrial types are differentiated from aero-derivative types by
       refer to generations of gas turbines. The first generation of gas  the fact the radial bearings are always hydrodynamic. Facts,
       turbines began in the 1950s, and progressed through the 1970s  advantages, and disadvantages concerning industrial turbines are
       (second generation) and 1980s (third generation) to present  presented in Figure 6.1.8. In recent years, the emphasis on ease
       day efficiency improvements.                          of maintenance has favored the aero-derivative type gas turbine
                                                            over either type of industrial gas turbine presented here. This is
                                                            because the maintenance times for the aero-derivative gas tur-
       Gas turbine classifications                           bines in the field are significantly less than industrial type gas
                                                            turbines, since the aero-derivative unit can be easily exchanged
       In this section, we will discuss the different gas turbine classi-  with a similar unit in the field. Therefore, the field maintenance
       fications in terms of design type, number of shafts, drive loca-  time is significantly lower for the aero-derivative gas turbine
       tion, and cycle.                                     (typically 72 hours as opposed to 360 hours or more).

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