Rate-Based Modelling and Simulation of Large-Scale CO2 Capture Using a Piperazine-Promoted Aqueous Ammonia Solution

Abstract

Due to the fast reaction rate of piperazine (PZ) with CO₂, it has the potential to act as a promoter in aqueous ammonia (NH₃)-based CO₂ capture processes. A rigorous, rate-based model for the NH₃–PZ–CO₂–H₂O system was developed using Aspen Plus^®, and validated against experimental results. Absorption and desorption processes were simulated under real flue gas conditions to gain a practical understanding of the behaviour and characteristics of interactions between PZ-promoted NH₃ solution and CO₂. Adding PZ significantly increased the CO₂ absorption rate in the NH₃-based CO₂ capture process via a fast reaction between PZ carbamate and CO₂. The temperature along the column was higher than in the absence of PZ, and additional NH₃ was released into the solution, which led to higher NH₃ loss. Adding PZ also reduced the stripping heat, resulting in a smaller energy requirement for solvent regeneration.