Effects of Air Ingress on Performance of Boiler and Air Preheater of Thermal Power Station

Abstract

Ever increasing imbalance between supply and demand of energy (especially electrical) existing not only in our country but worldwide, It is inevitable for developing countries like India to focus on increasing the generation capacity and energy conservation measures. As far as thermal power plants are concerned, there is huge potential of energy saving and increase in energy efficiency by minimizing losses and upgradation of technology. Compared to installation of new power generation unit which requires investment of several crores of rupees per MW set up, energy conservation is very effective and quick solution which requires very little investments. In thermal power plants, overall plant efficiency is dependent on multiple factors like boiler performance, auxiliary power consumptions, coal quality, turbine, condenser and generator efficiency, etc. In the present work, effects of air ingress on performance of boiler and air preheater have been investigated. Air ingress in boiler and air preheater results into the high auxiliary power consumption which ultimately leads to lower power generation capacity and increase in the heat rate. Air preheater leakages must be checked periodically and minimized to prevent the under performance of the unit resulting from overloading of fans. The objective of this work is to quantify air ingress & its effects on the energy efficiency of boiler and air preheater performance. In the present work air ingress sites have been identified by visual inspection during capital overhauling on unit-5. Also air ingress volume between different components of unit-5 of GSECL thermal power station at Wanakbori have been calculated using O2 mapping. The identified sites of air ingress have been rectified as well as internal leakages within air preheater has been arrested by replacing of various parts. Economic analysis before and after overhauling has been carried out to quantify saving in cost of fuel and fan power, which results into saving of crores of rupees. Further, recent advancements in air preheater technologies are described here which could be implemented to upgrade the existing air preheaters. Exergy analysis which provides deep insight of qualitative energy loss in the systems have been carried out for air preheater and boiler of units 4, 5 and 6. Second law efficiency of air preheater of units 4, 5 and 6 is found to be 55.18%, 57.55% and 51.96% respectively and that of boiler of units 4, 5 and 6 is 44.26%, 45.32% and 42.84% respectively.