(325c) Benchmarking of a New Absorption Mini-Plant

Chinmay Kale, Philip Lutze, Andrzej Górak

TU Dortmund University, Department of Biochemical and Chemical Engineering, Laboratory of Fluid Separations, Emil-Figge-Strasse 70, D-44227 Dortmund, Germany; phone: +49 (0) 231 755-3034, e-mail: chinmay.kale@bci.tu-dortmund.de

Keywords:Mass transfer kinetics, hydraulics, desorption, reactive absorption

Suggested theme: Process Development Division: Pilot Plants - Best Practices In Pilot Plants (12b01)

Flue gases from coal fired power plants and oil refineries are major contributors to CO₂ emissions and global warming. Post combustion CO₂ capture by reactive absorption using aqueous amines is seen as one of the most attractive solutions to reduce CO₂ emissions. Reaction kinetics and thermodynamics of this process has been extensively studied over the last decade. Before this technology can be successfully applied on industrial scale, a detailed analysis of mass transfer kinetics is necessary. In this regard, the behaviour of the process in columns of different dimensions is of specific interest.

For this purpose, a new absorption mini-plant has been installed at Laboratory of Fluid Separations, TU Dortmund university, Germany. This plant has three absorption columns having internal diameters DN25, DN50 and DN100 and variable heights from 1 m to 4 m. It also comprises of an upstream gas humidifier and a downstream batch distillation column for absorption solvent regeneration and uses common auxiliary equipment for the operation e.g. pumps, flow meters etc. The plant is equipped with a sophisticated control system which allows pressure drop, temperature and concentration (gas and liquid) measurements over the height of the columns. Different diameters, packings and column heights allow user to study the influence of column internals and hydrodynamics on absorption / desorption processes. The experimental results can be used to validate the rigorous absorption model.

Benchmarking of this mini-plant was carried out in three steps – a) hydraulic measurements to identify the operating range, to measure pressure drop and liquid hold-up, b) measurement of liquid side NTU and HTU by carrying out desorption experiments of CO₂ from H₂O into air and c) reactive absorption of CO₂ using monoethanolamine (MEA). Results of hydraulic and desorption experiments were compared with the results from open literature. Results of the reactive absorption were compared with results from other pilot absorption columns for the same gas as well as liquid loading and same compositions of the input streams. A generic non-equilibrium stage model was validated with the experimental results of reactive absorption CO₂.

After comparison of the model and experimental results without fitting any transfer parameters, it was found that the absorption mini-plant produced predictive experimental results with acceptable accuracy. Therefore, the mini-plant will be further used for detail mass transfer kinetics and scale-up related studies.