Absorption of Carbon Dioxide using Enzyme Activated Amine Solution in Columns with Random Packings

Abstract

Packed columns with structured or random packings are widely used in gas cleaning processes. Especially columns filled with random packings cover a large part of such applications in industrial practice. However, most of the recent investigation on carbon dioxide absorption from flue gases or other gas sources containing carbon dioxide (CO2) has been performed in columns equipped with structured packings, mostly due to their low pressure drop compared to other internals. CO2 usually is absorbed from the gas stream by means of a solvent. Amongst others, amine mixtures have gained a major role as a chemical solvent in this context. Beside the absorption kinetics and capacity, the energy demand for the regeneration of the solvent is a key factor for the operating costs of CO2 absorption plants. In previous studies, enzyme activated amines have been studied in lab scale, in order to enhance the absorption kinetics and to reduce the energy demand for regeneration. Besides the small scale, these studies focused almost exclusively on columns with structured packings. Despite the known benefits of structured packings, they can be inferior to random packings for systems with solid content and systems with mass transfer resistance in the liquid phase. Therefore, this work investigates columns at significantly larger scale equipped with random packings and presents the results of an extensive experimental study using the enzyme activated amine solution for the absorption of CO2. In particular, the different random packings McPac (Mackowiak 2001) from stainless steel and ENVIPAC from plastic have been studied in a test plant with diameter of ?? ?? =600 mm. Fluid dynamics and mass transfer characteristics have been measured using various liquid and gas loads, packing height and column diameter using the CO2 inlet concentrations of = 15 vol%. The experimental results are used for the validation of a process model, implemented in Aspen Plus® simulation software. A good agreement between experimental results and the simulation of the complex, reactive absorption system is established.