This paper describes the development of an ASPEN PLUS simulation model for a commercial NOx abatement system involving both absorption and selective catalytic reduction (SCR). The model helps identify operator guidelines and retrofit options needed to enable the commercial system to operate efficiently during surges in NOx-laden fumes without incurring costly fines. The resulting model applies a reactive-distillation module with a practical reaction set for NOx absorption and implements a kinetic model for SCR. The simulation results agree well with both design specifications and literature data and provide practical insights for optimum operation and economical retrofits of the commercial system.