Yoshiyuki Yamashita

Abstract:
This paper first introduces a semi-qualitative methodology to analyze a time trend based on a qualitative description with the addition of quantitative attributes. Using this methodology, it further defines a method to diagnose and qualify a control valve problem in a process control loop. Finally, the defined method of diagnosis successfully applied to several actual data sets from industrial chemical plants.

Keywords: process monitoring, process control, fault diagnosis, control valve, maintenance