Page 363 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer
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Be st Practice 6 .4           Gas Turbine Best Practices


        Function:    Quickly and effectively extinguish and confine  On-line cleaning should be performed periodically and
                     engine fires.                            frequently because:
        Protection     Carbon dioxide                           All particles must be removed immediately in a uniform manner
        mediums:       Halon (limited use in future – impact on ozone  to avoid destructive vibration.
                       layer)                                Cleaner injection rates and injection periods should be
        System features:  Multiple fire detectors             minimized to prevent:
                       Medium control system                    Erosion
                       Dispenses medium and trips engine on     Corrosion
                       confirmation of fire                    Cleaner composition must be confirmed to be satisfactory by
                                                             manufacturer to ensure:
                                                                Material and coating capability
       Fig 6.4.15   Gas turbine fire protection systems          Acceptable hot path component capability
                                                                Combustors
                                                                Nozzle, blade cooling passages
                                                               Entire cleaning procedure must be reviewed with engine
                                                               manufacturer.


                                                            Fig 6.4.17   Gas turbine cleaning systems on-line cleaning
        Function: To remove air compressor blade deposits and to restore  precautions
                power output and efficiency in a safe and reliable manner.
        Options:  Crank – performed at low (crank) speeds
                  H 2 O/glycol/detergent
                  H 2 O/glycol 1
                  On-line – performed at usually idle speed
                  H 2 O/glycol 2
                  H 2 O/glycol/detergent
                  Solid particle (walnut shells, catalyst) heavy duty only
             1
        Notes: Manufacturer must be consulted regarding acceptable
        cleaning procedures.
         2
         Must be used where operation below approximately 40° is possible.

       Fig 6.4.16   Gas turbine internal component cleaning systems

       Internal component cleaning
       Available power can be significantly reduced by engine fouling
       (accumulation of dirt on air compressor blades and stators).
       Most gas turbines incorporate some type of crank and/or on-line  Fig 6.4.18   The gas turbine accessory gear box DR 990 drive gear
       cleaning system. Figure 6.4.16 shows the function and options  module (Courtesy of Dresser Rand)
       for these systems.
          Figure 6.4.17 contains details concerning the cleaning
       system.
                                                            gear box connections for both industrial and aero-derivative gas
                                                            turbines are shown in Figure 6.4.19.
       Accessory gear box                                     Remember, the engine reliability is a direct function of the
       A picture of an accessory gear box used on a Dresser Rand DR  reliability of each individual system component! Required PM
       990 gas turbine is shown in Figure 6.4.18. The typical accessory  and an effective PDM program is a must!





                                   Industrial                  Aero-derivative
                                     Engine starter              Engine starter
                                     Main lube oil pump          Main lube oil pump
                                     Hydraulic (control oil pump)  Hydraulic (control oil
                                     Atomization air compressor (liquid  pump)
                                     fuels)                      Scavenge pump(s)
                                     Main fuel pump (liquid fuel)  Air/oil separator
                                     Cooling water pump (optional)


                                 Fig 6.4.19   Type accessory gear box connections

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