Investigation of Effective Parameters on Annealing and Hot Spotting Processes for Straightening of Bent Turbine Rotors

Authors: Esmaeil Poursaeidi, Mostafa Kamalzadeh Yazdi, Mohammadreza Mohammadi Arhani1

Abstract:

The most severe damage of the turbine rotor is its distortion. The rotor straightening process must lead, at the first stage, to removal of the stresses from the material by annealing and next, to straightening of the plastic distortion without leaving any stress by hot spotting. The straightening method does not produce stress accumulations and the heating technique, developed specifically for solid forged rotors and disks, enables to avoid local overheating and structural changes in the material. This process also does not leave stresses in the shaft material. An experimental study of hot spotting is carried out on a large turbine rotor and some of the most important effective parameters that must be considered on annealing and hot spotting processes are investigated in this paper.

Keywords: Annealing, Hot Spotting, Effective Parameter, Rotor

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1331391

References:

[1] E. poursaeidi, M. Salavatian, "Thermal simulation of rotor straightening," ICME, Johor Bahru, Malaysia, 21- 23 May 2008.
[2] R. V. Gestel, "Rotor repair," International Gas Turbines, ASME, Netherlands, No. 94-JT-351, 1994.
[3] D. Norfield, "Practical balancing of rotating machinery," First ed, Elsevier Ltd, pp. 39, 2006.
[4] "Bowed rotor straightening," Mechanical Dynamic & Analysis LTD, Private communication, 2011.
[5] G. S. Kim, J. E. Indacochea, and T. D. Spry, "Weldability Studies in Cr- Mo-V Turbine Rotor Steel," Proceedings of International Symposium on Welding Metallurgy of Structural Steels, Annual Meeting of The Metallurgical Society, Inc, Denver, Colorado, U.S.A., pp. 79-100, February 22-26 1987.
[6] R. E. Holt, "Primary concepts for flame bending," Welding Journal Vol. 76. pp. 416-424, 1971.
[7] C. W. Roeder, "Experimental Study of Heat Induced Deformation," Journal of Structural Engineering, ASCE, Vol. 112, No. 10, pp. 2247- 2262, 1986.
[8] O. Ditman, "Determination of Thermal Shrinkage in Structural Steel," MS Thesis, University of Washington, 1961.
[9] W. Chin, "Linear Shrinkage of Steel," MS Thesis, University of Washington, 1962.
[10] E. poursaeidi, A. R. Razavi, "The causes of local hardness increasing in power plant rotors and its modification by tempering," IJE Trans. Vol. 21, No. 3, pp. 267-274. 2008.
[11] H. P. Bloch, and F. K. Geitner, "Machinery Component Maintenance and Repair," Gulf Publishing Co, 3rd ed, Elsevier, pp. 476-479, 1999.
[12] "Heat Treating," Vol. 4, ASM Handbook, 1991.
[13] G. E. Thotten, and A. H. Howes, "Steels Heat Treatment Handbook," U.S.A. International Pub, pp.648-652, 1997.
[14] C. R. Brooks, "Principles of the Heat Treatment of Plain Carbon and Alloy Steels," The University of Tennessee, Knoxville, ASM International, pp. 162-164, 1996.
[15] G. T. Jones, and J. Gunning, "Causes for and Methods of Straightening Bent Turbine Rotors," ERA Technology, U.K., private communication, 1988.
[16] E. poursaeidi, A. R. Razavi, "An investigation on the causes of rotor bending and its thermal straightening," IJE Trans. Vol. 21, No. 3, pp. 281-290. 2008.