Development and verification of model predictive control strategy for selective catalytic reduction with rapid prototyping

Abstract

The International Maritime Organization has set forth strict regulations about the NO_x emission limit of ships to address the pollution problem in the transportation sector. Selective catalytic reduction (SCR) is the most effective post-engine means to reduce emission, and the control of urea spray critically affects the SCR performance. This paper developed a predictive control strategy of the SCR system based on the state space model. Specifically, the block model of the SCR reactor was established based on the reaction mechanism of the SCR system, and the unknown model parameters were identified. Rapid prototyping of the SCR system was carried out using the dSPACE real-time simulation platform to optimize the control under steady-state conditions. The catalyst ammonia coverage was set as the control target to maximize the NO_x conversion rate while maintaining the NH₃ escape at the outlet less than 10 ppm. The cyclic test results showed that the control strategy can quickly respond to external disturbance and modify the control target to keep the ammonia coverage rate within the target range, to thus achieve high NO_x conversion rate while maintaining the required ammonia escape.