Masaki Takaoka*, Nobuo Takeda*, Yasuhiro Oda**, Hiromichi Fujiyama***, Hideaki Fujiyoshi **** and Hayashi Morimoto*****

* Department of Environmental Engineering, Graduate School of Engineering, Kyoto University
** Institute for Environmental Management, Osaka
*** Japan Waste Research Foundation
**** Japan Environmental Sanitation Center
***** Towa Kagaku Co., Ltd.,

+ Correspondence should be addressed to Masaki Takaoka:
(Yoshidahon-machi, Sakyo-ku, Kyoto 606-8501 Japan)

Abstract

The service life expectancy of municipal solid waste incinerators (MSWIs) was estimated from both maintenance condition data of 87 MSWIs researched from 1994 to 1996, and from 1995 surveys on the decommissioning of MSWIs. First of all, in order to determine a mathematical model for the service life expectancy of MSWIs, normal distribution, logarithmic normal distribution and Weibull distribution were applied to the data from decommissioning MSWIs. Among these models, the compliance of Weibull distribution to the data was best. MSWIs had an average service life expectancy of 15.7 years, according to the decommissioning data, and 16.4 years when considering connection between each equipment from repair frequency data, applying Weibull distribution. By assuming that the ratio of maintenance costs to facility construction costs can be applied to Weibull distribution, service life expectancies were computed. The average service life expectancy of MSWIs with continuous stoker (boiler) was ranged from 18.2 to 37.4 years. The shape parameter in Weibull distribution indicates that MSWIs overall tended slightly to wear-out failure.

Key words: municipal solid waste incinerator, plant decommissioning, service life expectancy, Weibull distribution