Heat transfer analysis of energy and exergy improvement in water-tube boiler in steam generation process

Steam generation is an essential process in steel production. Saturated steam is used in the cold-rolling mills of sample steel company to raise the acid pool temperature. The studied water-tube boiler had a rated saturated steam generation capacity of 47 tons per hour. This study used energy and exergy balance equations for each of the components in the cycle to calculate exergy efficiency and irreversibility rate. Results from the exergy analysis along with the exergy dissipation rate of the cycle were obtained. Based on the literature results, it was recommended to increase the input air temperature by means of a preheater. First, the exergy dissipation in the boiler was reduced by 68 kJ kg−1 with the installation of an economizer. The most important cause of exergy destruction was then presented, and some recommendations were provided on how to increase the temperature of the makeup water in order to increase the boiler efficiency and exergy.