VARIABLES INFLUENCING THE EXERGY BASED PERFORMANCE OF A STEAM POWER PLANT.

In this study, energy and exergy analysis of a coal fired steam power plant in India was carried out and the effects of varying the reference ambient temperature, stack gas temperature and the percentage of excess combustion air on this analysis were examined through computer simulation. The combustion process in the boiler was analyzed in detail considering the actual composition and condition of atmospheric air and variation of specific heat of gases with temperature. Maximum energy loss was found in the condenser (62.02%) followed by the boiler (13.03%) while maximum destruction of fuel exergy was found in the boiler system (63.02%) followed by the turbine (9.35%), and then the condenser (3.24%). Significant potential to improve plant efficiency, therefore, exists through reducing irreversibility in the boiler system. The ambient temperature was found to have its highest effect on the changes of the irreversibility rate in the boiler as compared to that in other components. To examine the effects of stack gas temperature and the excess combustion air on the irreversibility rate of the boiler system, the stack gas temperature was varied from the existing 134.3°C to 90°C and the excess air percentage was varied from 25% to 5%. The results showed that decreasing either the percentage of excess combustion air or the exhaust gas temperature or both, causes the irreversibility rate in the boiler to decrease. [ABSTRACT FROM PUBLISHER]