Performance evaluation of a pressurized oxy-combustion power plant according to wet and dry flue gas recirculation

Abstract

In a pressurized oxy-combustion (POXY) power plant, it is essential to control the furnace temperature using flue gas recirculation (FGR) as an oxy-combustion environment produces an extremely high temperature in the furnace. However, FGR decreases the plant efficiency as it causes exergy loss in the furnace and increases the power consumption of the FGR booster fan. Therefore, to analyze a POXY plant, the effect of FGR on plant efficiency and performance should be evaluated. In this paper, an advanced supercritical pressure (A-USC) POXY power plant with a distributed pressurized oxy-combustion (DPOC) furnace is simulated and its performance for wet/dry FGR is analyzed. The furnace was modeled using an in-house code, and the whole power plant was simulated using commercial process simulation program. Plant efficiency with the wet FGR is 3.5% higher than that of the dry FGR system owing to the higher latent heat recovery of the FGC and reduction in the exergy loss. In addition, we demonstrated that variation of the plant efficiency for various flowrates of the recirculated gas was not significant in case of the wet FGR system, while considerable decrease in plant efficiency was observed for higher recirculation in the dry FGR cases. Accordingly, we presented an optimal A-USC POXY power plant system with a wet FGR system; the plant net efficiency improved by approximately 10% compared with that of a first-generation oxy-combustion power plant at atmospheric pressure.