Model for the Evaluation of Due Time for GE Frame 9E Gas Turbine Hot Gas Path Inspection (HGPI)

Abstract

This research study entails the determination of the due time required for carrying
out hot gas path inspection of a gas turbine. Delay in execution of HGPI may result
in machine failure, extra cost and loss in revenue while early execution may result
in unnecessary cost, waste, and loss in revenue due to downtime. Hence, the aim of
the research study, to model and evaluate the due time for carrying out hot gas
path inspection for a GE frame 9E machine. This study was conducted using GT17
of Transcorp Power Limited, Ughelli, Delta State. The methodological approach
considered for this study was to carry out a mathematical modelling approach in
determining the due time for carrying out HGPI. A corrosion rate formula was
developed, presented and used in the modelling process. The two main parts
considered for the experiment were turbine buckets and shroud blocks, which is
considered critical for the turbine clearance when undertaking HGPI. Based on
the mathematical modelling analysis, the due time for the turbine buckets were
24134.9hrs for stage 1, 235456hrs for stage 2 and 24727.5hrs for stage 3. In
correspondence, turbine shroud blocks due time were computed at 24805.3hrs,
24497.8hrs and 23346.1hrs for stages 1, 2 and 3 respectively. Based on the
efficiency computed, it was discovered that the efficiency of the gas turbine reduces
gradually until maintenance activities are carried out to improve the efficiency,
reliability and availability of the gas turbine.