Modeling hysteresis effects in boiler components

MSc thesis assignment

Electricity demand from individual power plants is expected to fluctuate increasingly due to the growing share of renewables such as wind derived energy. Operators of large Gas Turbine Combined Cycle (GTCC) power plants will have to deal with increasing load variations and rapid load changes. In the operation of power plants, there is always a trade-off between the rate of load variation and the strain which is put on components (especially the boiler), which is directly correlated to materials degradation and maintenance
costs. It is therefore of great interest to study the mechanisms of thermal stress evolution in critical boiler components. Thermal fatigue resulting from transient conditions causes alternative tensile and compressive stresses in a component (the so-called hysteresis loop) which exaggerate stress conditions both at the surface of a component and in the root area of any small cracks/defects that exist within the material [1].

 This MSc thesis project is part of a research project for GDF SUEZ Energy NL, aiming at increasing the flexibility and reliability of the Maxima power plant, a GTCC plant recently built by Alstom in Lelystad, The Netherlands. The plant has been in commercial operation for about  2,5 years. The aim of this thesis is to gain thorough understanding of the above mentioned phenomenon and to create models which can predict these effects in critical components. The input to such a model should be the transient signal of the
steam conditions as can be measured (pressure temperature, mass flow), and the output should be an estimation of the evolution of stress in critical parts. The application of such models is in damage mitigating control of boilers [3]. Furthermore, it might be worth wile to study the link between stress evolution and thermodynamic irreversibility [4].

Supervisors:

Ir. Sowande Boksteen* PhD student GDE-SUEZ/TUDelft
Dr. Rene Pecnik Assistant professor TUDelft
Bendiks-Jan Boersma Professor TUDelft

email: s.z.boksteen@hotmail.com

Literature
[1] CASE STUDIES I N ENGINEERING DESIGN iVIatthews, Clifford 1998
[2] A LITERATURE REVIEW ON FATIGUE AND CREEP INTERACTION Wen-Ching
Chen NATIONAL AERONAUTICS AND SPACE ADMINISTRATION NCR 33-022-157
[3] OPTEVIAL LIFE-EXTENDING CONTROL OF B OILER SYSTEM D. L i , H J . Marquez, T. Chen and R.K. Gooden 2006 lEE
[4] MATHEMATICAL MODELS OF HYSTERESIS AND THEIR APPLICATIONS
Mayergoyz, I.D. 2003 p.60-61