MODELING AND EVALUATION OF EXTERNALLY FIRED COMBINED-CYCLE USING ASPEN

A new performance model of the externally fired combined cycle (EFCC) is implemented in ASPEN (Advanced System for Process ENgineering), a c hemical process simulator The model accounts for interactions within a nd between approximately a dozen major process areas. The new model is applied to case studies to evaluate the sensitivity of process perfor mance to the ranges of uncertainty in key model inputs such as heat lo sses, carbon conversion, and air leakage rates, and to illustrate how alternative designs, including steam injection and flue gas desulfuriz ation (FGD), can affect plant thermal efficiency and net power output. The model results suggest that careful attention to the design of the FGD system is needed, especially with respect to reheat, and that ste am injection may offer cost savings associated with reducing the size of the steam turbine with little or no penalty on plant output or plan t efficiency. Uncertainties in the slagging combustor and the ceramic heat exchanger may lead to significant penalties on process performanc e.