Design Optimization of Boiler Tail Flue in Supercritical Carbon Dioxide Power Generation System

Abstract

The S-CO2 top-bottom combined cycle based on overlap energy utilization can lead to excessive heating area, due to the small temperature difference and the large thermal load for the heating surface at the tail of the boiler. Therefore, reasonable optimization indexes are needed for design optimization. Common optimization indexes include heating area and working medium pressure drop, but lower working medium pressure drop usually leads to large heating area, for example, with the increase of tube inner diameter or boiler width, the pressure drop decreases but the heating area increases. Thus, if both are used as optimization indexes, it will be difficult to choose the optimum tube inner diameter and boiler width. In this paper, exergy loss analysis is used, in combination with economic analysis, the optimization index is unified to the cost per unit heat transfer of the heating surface. The thermal calculation and pressure drop calculation models are established for the heating surface at the tail of the boiler. The optimized heating surface can greatly improve the economic benefit.