Load-based Exergetic Assessment of an Offshore Thermal Power Plant in an Equatorial Environment

Abstract

The Load-based exergetic assessment of a thermal power plant for offshore utilization was carried out. The gas turbine systems were split into sub-systems and simplified into control volume to show inflow and outflow of exergy at different loading. The operating parameters of the plant were monitored for 12 months through human machine interface (HMI), and the data collected were used with thermodynamic relations to carry out the assessment.  MATLAB 7.3 ^® Software was used to evaluate the various model equations and results tabulated. The results show that for every 1% drop in the operational load, the thermal efficiency and exergy efficiency drop by 0.17% and 0.25% respectively. It further shows that there is about 0.006% decrease in fuel consumption under the same conditions, and at 44% loading the system has the highest percentage of exergy loss of about 21.3%. This means that as the operational load decrease, the percentage exergy loss increase proportionally. Enormous exergy is lost in the exhaust system due to absence of heat recovery steam generator. The assessment established that the components of the power plant degrade in the quality of exergy and performance at different loading of the plant due to mechanical loss and irreversibility.