ENVIRONMENTAL MODELLING

In order to address the growing global energy demand and reduce the environmental impact from operating gas turbine power plants, the performance and how to improve existing gas turbine power plants need to be studied. In view of this, this research work aims at carrying out the thermodynamic and environmental analyses of Azura Edo Power Plant for design and off-design conditions. Ebsilon Software is a commercially accepted energy and mass balance tool for power plant modelling. The performance of the Azura Edo Power Plant at design and off-design conditions were modelled using Ebsilon Software and the simulation exercise was validated. Energy, exergy and environmental analyses were conducted using operating data collected from the power plant to evaluate the thermal efficiencies, heat rate, energy losses and exergy destruction of each major component of the power plant and carbon dioxide emission rates with the aid of MATLAB software. The effects of ambient air temperature on the thermodynamic and environmental performances were carried out. Preliminary analyses of the effect of integrating an inlet air cooling system and heat recovery steam generator (HRSG) for future consideration were conducted. The results obtained from model validation were -3.13% to 0.88% for design and -3.24% to 2.66% for off-deign conditions. This showed that the model data were found to be in good agreement with the International Standard Organization (ISO) and Azura Edo guaranteed data for both design and off-design conditions. Energy analysis results obtained showed that the average net thermal efficiency of the three units was found to be 29.79% at the ambient air temperature range from 21 to 35 0C, the compressor pressure ratio of 10.72 to 10.96 and net power output of 148.92 to 160. 70MW. Also, results obtained showed that there was a lower performance of the plant at high ambient air temperature and a lower compressor pressure ratio. The exergy analysis results indicate that the combustion chamber has the least exergy efficiency and highest exergy destruction efficiency compared to other components studied. Findings from the research revealed that the combustion chamber also has the largest improvement potential of 101.07 to 107.23MW among the components considered. The environmental analysis results obtained showed that the average emission of CO2 for Azura Edo Power Plant was 707.741kgCO2/MWh and 690,602,489.84kgCO2/yr, which the latter is within the guaranteed values of 726,000,000 kgCO2/yr. At high ambient air temperatures, low exergy and the second law of thermodynamic efficiencies, sustainability of fuel and high exergy destruction efficiency, depletion of fuel and CO2 emission rates were observed. It was also observed from the preliminary analyses that the incorporation of air intake cooling system and HRSG caused 95.2341kgCO2/MWh and 73,542.0651kgCO2/yr; 181.52kgCO2/MWh reduction in CO2 emission respectively. The study established that the incorporation of an inlet air cooling system to maintain low compressor air inlet temperature, HRSG and steam turbine to utilize the high temperature of the flue gas to improve the plant performance was economically and environmentally feasible. Accordingly, the study has provided an understanding of suitable methods for efficient and waste minimization as ways of performance enhancement of Azura Edo Power Plant