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					               ETN’s Working Group 4


On Line and Off Line Turbine Washing
      Which solution and when?

      Update on work progress
                     Università di Genova
    Dipartimento di Macchine, Sistemi Energetici e Trasporti
The study is being performed since February 2009 by:
           Andrea Fabbri, Undergraduate student

Academic supervisors
      Dr. Alberto Traverso, Silvio Cafaro
                  University of Genoa, Italy




Supported and sponsored by

       European Turbine Network
5/2/2011                                               2
                 Project scope
• Investigate the different technologies and methods
  employed in on-line washing.
• Present the relative merits of on-line washing.
• Identify problems which can relate to on-line washing.
• Present the financial benefits and cost associated with
  on-line washing.
• Provide best practice reference guide to the
  application of on-line washing, for example the
  installation specifics, turbine type, technology used,
  operational regime, regional location, industry
  business and cost benefits.

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                     OUTLINES
   1. Collection of information, references, papers
      about compressor fouling issues, washing
      compressor systems, filter systems.

   2. Data processing and preparation of preliminary
      State-of the-art of compressor cleaning and
      filter systems

               WORK IN PROGRESS
      State-of the-art of compressor washing
             tool for decision support
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           Compressor fouling
“...Fouling is defined as degradation of
flow capacity and efficiency caused by
adherence of particular contaminants
to the gas turbine engine airfoil and
annulus surfaces...” ( E. Syverud)


Deposition of dust depends on the kind of
pollutant: hydrocarbons, oil, coal, salt, ash,
fertilizing, insect, pollens, sand, spores ...
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                Compressor fouling
   A few fouling effects are:
   •Abrasion of rotating surface and material corrosion.
   •Reduction of compressor discharge pressure.
   •Reduction of mass flow rate (reduction of effective
   flow area).
   •…..




    Lower output power and compressor efficiency.


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       Economic evaluation (Diankunchak ,1991)
An example with CW251B12 Econopac Engine, simple
cycle, natural gas fuel.
Net output power = 46,5 MWe.
Average yearly decrease in power of 3 %
Increase in fuel consumption of 1 %.
Cost of fuel about $ 0,007/kWhth
Cost of energy $ 0,04/kWhe




       The total yearly cost of the assumed average
 performance deterioration is about $ 500,000, i.e. around
                     3% of capital cost
5/2/2011                                                     7
                  Washing System
• Off line washing : injection of the cleaning solution at sub-idle
  shaft speeds.
  Pro: Excellent deposit removal.
  Con: Production losses.

• On line washing : injection of the cleaning solution while the
  engine is running at peak load.
  Pros: No time losses, boost due to added mass-flow during the
  washing.
  Cons : Partial removing deposit, blade erosion by droplet
  water.

    On line washing is often combined with off-line washing to
    optimize uptime while maintaining an acceptable thermal
    efficiency.
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     Relative Gas turbine capacity with washing




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               Online Washing
Effectiveness of on-line washing depends on:

•Site and type of dust ingested. (salt near the coast)
•Use of detergent.
•Location of nozzle.
•Droplet size. (75-100 µm )
•Water injection velocity.
•Washing frequency. (every day, 2-3 times at week)


5/2/2011                                                 10
           Preliminary State-of the-art
From a database of 98 GT (courtesy of VGT):

• 94% use off line cleaning with detergents.

• 75% use on line cleaning, 94% only with water.

• 51% on-line cleaning every day, 19% 2-3 times
a week, 5 % once a week.


5/2/2011                                           11
                  Filter system
International rules like EN 799 and EN1822 unify the
filter performance, such as:
• Cut-off
• Pressure drop
• Efficiency of filtration.
There are three main ways to capture particles:
• Sieve effect: dust particle is caught between fibres.
• Diffusion effect: The particle collides with the fibres
    and is held there by intermolecular forces.
• Electrostatic effect: with polarized fibres.
5/2/2011                                               12
           Filter system outline
Two main technologies:

1. Two-stage filter: less filtration efficiency, lower
   power losses (lower inlet pressure drop).
   Compressor needs periodic washing.

2. Three-stage filter: high filtration efficiency, reduced
   need of washing, higher power losses.

Schroth T. , Cagna M. (ASME GT2008-50280) showed the
economic benefit of 3-stage filter for a turbine rated at
165 MW , with 6300 MWh/annum gained and 198000
eur saved
5/2/2011                                                13
           Future program
• Collecting data for state-of the-art, new
  questionnaire.




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           Questionnaire




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            Future program
• Collecting data for state-of the-art, new
  questionnaire.
• Improve knowledge about filter system and
  their performance.
• Preliminary tool for decision support on the
  best cleaning devices.
• Attempt: to develop a new Software tool for
  economic optimization of on line and off line
  washing frequency

5/2/2011                                      16
              Acknowledgements
This work has been funded and supported by ETN, which is
   greatly acknowledged. In particular, the author wishes to
   thank Kat Cheung and Francisco Zamora of ETN for the
   availability and help.

A special thank to P. Andersson (GTE), G. De Arcangelis
  (TRASMISSION TECNOLOGY), K. Langnes (ECOSYS), M. Mulder
  (Gas turbine Association – VGT), T. Valen (STATOILHYDRO), for
  the valuable technical advise and information provided.

Another thank to D. Schiavina ( ROQUETTE ITALIA ) for the
  permission to assist at an on line cleaning in the power plant
  of Cassano Spinola.



5/2/2011                                                       17
                      Main References
 •E.Syverud , “Axial Compressor Performance Deterioration and Recovery through
 Online Washing” , Ph.D NTNU, ISBN 978-82-471-1884-9, 2007.

 •Diakunchak, I. S., ‘‘Performance Deterioration in Industrial Gas Turbines,’’ , ASME
 Paper No. 91-GT-228, 1991.

 •Schroth T. , Cagna M., 2007 “Economical benefits of highly efficient three-stage
 intake air filtration for gas turbines”, ASME Turbo Expo 2008: Power for Land, Sea
 and Air GT2008, Berlin, Germany, ASME GT2008-50280, June 9-13 2008.

 •GT filters’ Costs & Media Available, De Arcangelis G, Personal communication,
 TEL. +44 (0)845 838 5546.

 •Litinetski A., Litinetsky V., Hain Y., Gutman A., " Parametric study of on-line
 compressor washing systems using CFD analysis ", ASME Turbo Expo 2008: Power
 for Land, Sea and Air GT2008, Berlin, Germany, ASME GT2008-50423, June 9-13
 2008.


5/2/2011                                                                                18
           Thank you




5/2/2011               19
               ETN’s Working Group 4


On Line and Off Line Turbine Washing
      Which solution and when?

      Update on work progress
                     Università di Genova
    Dipartimento di Macchine, Sistemi Energetici e Trasporti
                           Examples
                                   Nozzle located in the inlet bell


                                   Big droplet at high speed couldn’t
                                   enter in the compressor.

               Testo del lucido
                                   Big droplet are able to erode the
                                   blades and reaches the bottom of
                                   compressor stage difficulty, but clean
                                   compressor better, than small
                                   droplet.



On line cleaning is possible when environmental temperature is
above than a recommended temperature ( for example 15°C), to
avoid the icing issue.
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