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Advances in Materials Science and Engineering
Volume 2015, Article ID 275340, 11 pages
http://dx.doi.org/10.1155/2015/275340
Research Article

Soft Sensor for Oxide Scales on the Steam Side of Superheater Tubes under Uneven Circumferential Load

1Energy and Environment Department, Southeast University, Si Pai Lou No. 2, Xuan Wu District, Nanjing 210096, China
2School of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing, China

Received 31 December 2014; Accepted 8 February 2015

Academic Editor: Chih-Chun Hsieh

Copyright © 2015 Qing Wei Li and Gui Huan Yao. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A soft sensor for oxide scales on the steam side of superheater tubes of utility boiler under uneven circumferential loading is proposed for the first time. First finite volume method is employed to simulate oxide scales growth temperature on the steam side of superheater tube. Then appropriate time and spatial intervals are selected to calculate oxide scales thickness along the circumferential direction. On the basis of the oxide scale thickness, the stress of oxide scales is calculated by the finite element method. At last, the oxide scale thickness and stress sensors are established on support vector machine (SMV) optimized by particle swarm optimization (PSO) with time and circumferential angles as inputs and oxide scale thickness and stress as outputs. Temperature and stress calculation methods are validated by the operation data and experimental data, respectively. The soft sensor is applied to the superheater tubes of some power plant. Results show that the soft sensor can give enough accurate results for oxide scale thickness and stress in reasonable time. The forecasting model provides a convenient way for the research of the oxide scale failure.