Multistep SO₂ absorption – Making process design choices based on process simulation

Abstract

This study proposes two different process designs of a multistep SO2 absorption process using an Mg(OH)2 slurry. The first design aims to absorb as much SO2 as possible in as few steps as necessary until a target SO2 content in the exhaust gas is reached. The second design focuses on reaching the target SO2 content in the exhaust gas and minimizing the chemical loss due to precipitation in the system. The process designs were designed and calculated using the process simulation environment of Aspen Plus® V10. The results show that the target SO2 limit is reached after four absorption steps for the first process design. However, the precipitation loss makes up almost 20 wt% based on the product output. The second design requires eight absorption steps to reach the target SO2 limit in the exhaust gas. However, the precipitation loss can be reduced to 5 wt% based on the product output. The results suggest that minimizing precipitation in the system can improve material process performance