Developement of inspection method of both front side and rear side carburization depth in heating furnace steel tube using alternating magnetic field

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K01299
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Social systems engineering/Safety system
• Research Institution: Oita University
• Principal Investigator: Gotoh Yuji 大分大学, 理工学部, 准教授 (00373184)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 石油精製プラント / 加熱炉鋼管 / 表裏面浸炭深さ / 交流磁界 / 三次元非線形磁界解析

Outline of Final Research Achievements

In the steel tube of a large-sized heating furnace in an oil-refining plant, both the front side and rear side are carburized because of being used for many years in high-temperature environments. If these carburization depths increase the steel tube will explode suddenly and a big accident may occur. Therefore, the measurement of both the front side and rear side carburization depth are important in order to prevent accidents. In this research, an electromagnetic inspection method using two kinds of exciting frequency for the carburized depth of both the front side and rear side of the steel tube is proposed. Both carburization depths are obtained by evaluating the flux density in layers with and without carburization using the 3-D nonlinear FEM. It is shown that the inspection for the carburization depth of both the front side and rear side of the steel tube is possible by using the deference in permeability and conductivity of carburized layer.

Free Research Field

計測工学

Academic Significance and Societal Importance of the Research Achievements

東日本大震災以降、日本では原子力発電所の使用が制限され、火力発電所とその原料供給のための石油製油所の稼動率が一気に高まった。石油製油所は、大震災以前は生産が縮小傾向であったため、中には老朽化が激しく、十分な設備更新が行われないままフル稼働を余儀なくされている製油所も多くある。特に製油所内の加熱炉鋼管の浸炭に伴う破裂事故が近年急増しており、非破壊検査法の開発が強く求められている。しかし、この加熱炉鋼管の浸炭度合いを非破壊で検査できる手法は無い。本研究では、加熱炉鋼管に生じている浸炭度合いを高速かつ簡便に診断する新しい電磁非破壊検査技術の開発を行い、石油製油所の事故を未然に防ぐ事を目的としている。