Portal de Periódicos da CAPES

Is Closed-Loop SCR Control Required to Meet Future Emission Targets?

2007; Linguagem: Inglês

10.4271/2007-01-1574

2688-3627

Frank Willems, Robert Cloudt, Edwin van den Eijnden, Marcel van Genderen, R.P. Verbeek, Bram de Jager, Wiebe Boomsma, Ignace van den Heuvel,

Industrial Gas Emission Control

To meet 2010 emission targets, optimal SCR system performance is required. In addition, attention has to be paid to in-use compliance requirements. Closed-loop control seems an attractive option to meet the formulated goals. This study deals with the potential and limitations of closed-loop SCR control. High NO x conversion in combination with acceptable NH 3 slip can be realized with an open-loop control strategy. However, closed-loop control is needed to make the SCR system robust for urea dosage inaccuracy, catalyst ageing and NO x engine-out variations. Then, the system meets conformity of production and in-use compliance norms. To demonstrate the potential of closed-loop SCR control, a NO x sensor based control strategy with crosssensitivity compensation is compared with an adaptive surface coverage/NH 3 slip control strategy and an openloop strategy. The adaptive surface coverage/NH 3 slip control strategy shows best performance over simulated ESC and ETC cycles. SCR catalyst dynamics, time delay in the urea injection and maximum NH 3 slip targets limit the performance of closed-loop SCR control. If new reagent dosage systems and future catalyst technology are able to relieve these limitations, closed-loop control has the potential to reduce the calibration effort and to improve the transient control performance.