Response Surface Methodology-Based Model and Optimization of CO2 Absorption Using Methyldiethanolamine Activated by Piperazine

Abstract

The purity of CO2 in a urea plant is strongly influenced by the absorption process, starting from operation temperature and pressure until the concentration of the absorbent material. All the independent variables of the process should be maintained and adjusted to reach optimal condition which is 99% (v/v) of the purity of CO2. Response Surface Methodology (RSM) installed in Design-Expert® 10 software was applied to develop a reliable model that can be used to optimize the absorption of CO2 using methyldiethanolamine (MDEA) activated by piperazine. Training data of 54 runs with constrained different values of six independent variables correlated with the Box-Behnken design were taken into account from the Main CO2 Removal unit at the PT. Pupuk Iskandar Muda-2 of ammonia plant in Lhokseumawe of Aceh Province. As the result, the model-based result was in a very good agreement with the experimental result (R2 = 0.99) which was also confirmed by the ANOVA, and an optimized CO2 purity of 99.20% (v/v) was obtained by desirability function. Using the model and Levenberg-Marquardt method, further optimal condition of CO2 absorption was also worked out by minimizing the MDEA concentration to 39.00% (v/v). The final optimized CO2 purity was approximately 99.46%.