Abstract
This study examines a combined cycle plant powered by a Siemens STG-800 gas turbine, producing 47.5 MW of electricity and 81,908 kg/h of steam via a MACCHI Heat Recovery Steam Generator (HRSG). The plant is part of a refinery’s steam and electricity generation section in Cartagena de Indias.
Owing to the differences between Cartagena’s conditions and ISO standards, evaluating component performance under actual operating conditions is crucial. Methodologically, the methodology involved defining thermodynamic principles “visual inspection of the compressor with a borescope”, conducting energy balance assessments, and establishing performance parameters to compare the model fit with the manufacturer’s values. Exergy balances were developed to determine the exergy destruction rates and overall exergy efficiency, explore component interactions, and identify improvement areas. Exergoeconomic analysis quantified monetary losses and recovery capacity. To develop the maintenance program, the performance degradation due to compressor and gas turbine fouling and erosion was evaluated over time. The proposed maintenance indicators and criticality matrix allowed the prioritization of timely maintenance to restore lost efficiency and optimize cost-benefit ratios.
The average model adjustment error was 2%. Exergetic analyses pinpointed day 206 as the peak exergy destruction, with the gas turbine compressor exhibiting the most significant interaction with irreversibilities. Exergoeconomic analyses showed that the equipment relying on chemical reactions incurred the highest exergy destruction costs. Maintenance recommendations suggest advancing Maintenance Types A and B while extending Maintenance Type IV beyond the manufacturer’s specifications.
