• Energy Research

Abstract Improved kinetic models based on penetration theory for CO2 capture process by aqueous Monoethanolamine (MEA) solution are developed within MATLAB software in this study. Base contributions of major bases MEA and H2O present in the solution are considered in the carbamate formation reaction and termolecular reaction mechanism is used for carbamate formation. Both concentration based and activity based kinetic models are valid over the temperature range of 293–343 K, CO2 loading range of 0–0.5. The concentration based kinetic model is valid for MEA concentrations up to 5 M and activity based kinetic model is valid up to 9 M MEA. The developed kinetic models are validated with experimental absorption data from strings of discs, wetted wall column and laminar jet absorber. Both models predict absorption rates as well as desorption rates with good accuracy.

AbstractThe kinetics of CO2 reacting monoethanolamine (MEA) and 3-(methylamino)propylamine (MAPA) solutions are studied by conducting absorption rate experiments in two different apparatuses: a wetted wall column and a string of discs column. It is shown that the apparatuses give comparable results.The results are modeled using the direct kinetic mechanism with activity-based rate expressions, and good representation is obtained.

Abstract In order to design absorption and desorption towers several properties of the chemical system must be accurately calculated using models based on experimental data. In the present work, the densities of aqueous solutions of MDEA (N-methyldiethanolamine), DMEA (N,N-dimethylethanolamine), DEEA (diethylethanolamine) and MAPA (N-methyl-1,3-diaminopropane), potential solvents for CO2 capture, are presented. The density of unloaded solutions is modelled by using the Redlich–Kister model with 3 parameters. An empirical proportionality model that correlates the density change due to CO2 loading to the amount of CO2 loaded is also presented. The proportionality model is able to adequately predict the density of loaded solutions with only two extra parameters. Densities for loaded and unloaded MEA (monoethanolamine) aqueous solutions were also correlated with data from literature by the presented models. A comparison between the performance of the Redlich–Kister, the proportionality model and the Rackett models is presented. It is shown that the Rackett model can be used to give a good estimate for the liquid densities. However, the accuracy is in general one order of magnitude lower than for the Redlich–Kister fit and the maximum absolute deviation can be 8 times higher than the one calculated with the proportionality model.

Abstract Solution densities and viscosities are important parameters for the design and simulation of absorption processes. Accurate models are needed and in this work, a new model for calculating the liquid viscosity of mixtures is presented. The model uses an analogy to excess Gibbs energy models to account for the deviation from a simple mixing rule based on the pure component viscosities. In this work, we chose the functional form of the NRTL model to represent the excess Gibbs energy and the resulting model is referred to as NRTL-DVIS. Eleven systems (eight binaries and three ternary) were chosen for testing the accuracy of the model. The ternary systems were built from the optimized binaries and pure component systems. With few adjustable parameters, the NRTL-DVIS model represented the tested systems with good accuracy. With few exceptions the calculated total deviation (AARD) was within 3.5%. The NRTL-DVIS model shows better accuracy than other models proposed in the literature.

The absorption process is strongly influenced by the effective contact area. In absorber columns, this is related to the type of the internals used in the columns. Therefore, a good representation of the effective mass-transfer area and mass-transfer coefficients (kL or kg) is also essential for accurately represent and design a process. For CO2 capture process packed columns are usually preferred. The mass transfer area and coefficients for several packing (both structured and random) are correlated elsewhere. In this work mass transfer experiments using concentrated MEA solution in the Procede acid gas treating pilot plant are performed. However, due to the fast reaction between MEA and CO2, both the gas side and liquid side mass transfer resistances are relevant and the mass transfer area cannot be determined experimentally. Nevertheless, the volumetric mass transfer coefficient is calculated and it showed to be relatively constant for all the runs. The results from the pilot plant are compared to simulated results using Procede Process Simulator (PPS). The mass transfer area and mass transfer coefficients were calculated through the default correlations implemented in PPS. Very good agreement is achieved between the experimental and simulated results.

AbstractIn this work the potential of a novel post-combustion CO2 capture process is analysed with respect to the integrated overall process. As solvent a blend of two amines (DEEA/MAPA) which forms two liquid phases under CO2 loading is used. The two phases have distinct physical characteristics. Only the heavy phase, rich in CO2 loading, is led to the desorber. The novel solvent combination promises very low energy consumption compared to a 30wt.-% MEA solution. The efficiency penalty, taking into account the integrated overall process, is very low too. Furthermore, different integration configurations in the overall process are investigated to show the effect in greenfield and retrofit power plant cases.

© 2016 Elsevier B.V. or its licensors or contributors. This is the authors’ accepted and refereed manuscript to the article.