Second law approach in the reduction of gas emission from gas turbine plant

Abstract

This paper presents second law analytical approach in reducing gaseous emission at gas turbine plant in Geregu, Nigeria. The study analyzed the system's components separately to locate the component with highest exergy destruction ratio for possible improvement. Results show that the combustion chamber has highest exergy destruction ratio. Improvements made include increment in: (i) turbine inlet temperature at constant pressure ratio, (ii) combustion chamber pressure ratio at constant turbine inlet temperature, (iii) both turbine inlet temperature and pressure ratio, and changing ambient temperature at power plant location. The multiple criteria for change indicate that the first approach decreased the environmental effect factor by 6.96 % and the sustainability index factor increased by 7.41% as the temperature increased from 1060 – 1080 oC at constant pressure ratio of 11. The second approach reduced the environmental effect factor by 2.74% and increased the sustainability index factor by 2.82% when the pressure ratio rose from 11 to 15. However, simultaneous increments in turbine inlet temperature and pressure ratio by 20oC and 4bar decreased the environmental effect factor further by 8.41%. Thus, raising the sustainability index factor by 9.19%. The results show that changing the ambient temperature from 20°C to 35°C resulted in equal changes in environmental effect factor and sustainability index factor by 0.02%. This work has revealed that gaseous emission from the plant can be reduced by second law analysis. Overall, simultaneous increases in pressure ratio and turbine inlet temperature gave the best result.