PERFORMANCE EVALUATION AND IMPROVEMENT OF BOILER EFFICIENCY N. Jashuva 1 Smt.G.V.NAGAMANI 2 1. Department of mechanical engineering, Global College of Engineering Kadapa, A.P., India. 2. Assoc.Professor&Head , Department of Mechanical Engineering, Global College of Engineering, Science & Technology, Kadapa, A.P., India Abstract: performance prevenve measures for corrosion of heang elements has been studied, and also air heater leakage, corrected gas outlet temperature and finally gas efficiency has been calculated .Air pre-heater is a heat transfer surface in which air temperature is raised by transferring heat from other media such as flue gas .Hot air is necessary for rapid combuson in the furnace and also for drying coal in milling plants. So an essenal boiler accessory which serves this purpose is air pre-heater. The air pre-heater are not essenal for operaon of steam generator, but they are used where a study of cost indicates that money can be saved or efficient combuson can be obtained by their use. The decision for its adopon can be made when the financial advantages is weighed against the capital cost of heater in the present paper we have taken up the operaon and performance analysis of LJUNGSTROM AIRPREHEATER27VITM 1900 of 2x210 MW capacity Rayalaseema Thermal Power Plant, Kalamala and compare with Rothemuhle air pre-heater. Key words: Thermal power plant, energy, air pre heater, Rothemuhle air pre-heater 1. INTRODUCTON Figure 1: 3-D View of Ljungstrom Air pre-heater The Ljungstrom air pre-heater is more widely used than any other type of heat exchanger for comparable service. The reasons for this world wide acceptance are its proven performance and reliability, effecve leakage control, and its adaptability to most, any fuel burning process. It is both designed and built to operate over extend periods with durable, uninterrupted service. Simplicity of design also makes it easy and economical to maintain while in operaon and at scheduled outages.