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This article presents a study on the optimal design and operation of a pilot-scale absorber column in post-combustion CO2 capture in the presence of uncertainty. A mechanistic model describing the behaviour of a post-combustion CO2 absorber column is explicitly considered in the present robust optimization formulation. This formulation takes into account process uncertainty, which will impact the absorber column operation due to seasonal or unexpected changes in the operating policies of a fossil-fired power plant, e.g. changes in the flue gas stream. Different scenarios were assessed in order to evaluate the impact of uncertainty on the optimal process design and operation. The results show that environmental constraints determine the impact of process uncertainty in the operation of the absorber column. Similarly, the operation of the absorber unit may become infeasible even when process design specifications are estimated under limited information on process uncertainty.

CO2 capture performance of 50 wt.% K2CO3/alumina was investigated using various types of alumina supports such as γ-Alumina, Boehmite and Aerogel. Physical mixing and incipient wetness impregnation were used for preparing sorbents. Physically mixed K2CO3/γ-Alumina was the most efficient sorbent, with a maximum CO2 capture capacity of 5.5 mmol CO2/g K2CO3. γ-Alumina displayed the lowest, and Aerogel the highest, hydrophilicity and surface area. Increasing hydrophilicity and surface area also increased water adsorption capacity, which adversely affected the CO2 capture capacity of the physically mixed sorbents. The excess water adsorption capacity converted K2CO3 to an almost inactive precursor of K2CO3·1·5H2O. BET and SEM results showed that recrystallization of K2CO3 from water had an adverse impact on the physical structure of the impregnated sorbents which affected their CO2 capture performance. The kinetic behavior of the samples was analyzed using the Avrami kinetic model. K2CO3/γ-Alumina prepared by physical mixing and impregnation methods showed the highest carbonation rates with K-values of 0.1168 and 0.2260, and n-values of 1.1257 and 1.2004, respectively. K2CO3/Aerogel and K2CO3/Boehmite prepared by the physical mixing method exhibited higher performance than the respective impregnated sorbents in terms of carbonation rate and CO2 capture capacity.

This work presents a mathematical modeling framework for the simulation and optimization of pressure/vacuum swing adsorption (P/VSA) processes for post-combustion CO 2 capture. A single-stage P/VSA process for CO 2 capture from dry flue gas is considered using new zeolite 13X-based adsorbents resulting from perturbation on the 13X zeolite isotherm. A two-bed six-step P/VSA cycle configuration with light product pressurization is employed in systematic simulation and optimization studies. First a zeolite 13X, the current benchmark commercial adsorbent for CO 2 capture, is considered. Accordingly, the model is used to study and evaluate new zeolite 13X-based adsorbents for more efficient CO 2 capture. The results from systematic comparative simulation studies demonstrate that a modified zeolite 13X-based adsorbent appears to have better process performance compared with the original zeolite 13X. Furthermore, process optimization studies employing the above potential adsorbents are performed to minimize energy consumption for specified minimum requirements in CO 2 purity and recovery. The optimization results indicate that the minimum target of 95% in CO 2 purity and 90% in CO 2 recovery is easily met for the P/VSA process under consideration for both potential adsorbents under different operating conditions resulting in different energy requirements and CO 2 productivity.

This paper presents optimal operating conditions for the post-combustion CO2 capture process utilizing aqueous amine solutions obtained using a process simulator (HYSYS). Three alkanolamine solutions (Methyldiethanolamine MDEA, DiEthanolAmine DEA and MDEA-DEA mixture) are considered to study the performance of the capture process.The design problem addressed in this paper requires specifying the optimal operating conditions (inlet and outlet temperature of the lean solution stream on the absorber, CO2 loading, amine composition and flow rates, among others) to achieve the given CO2 emission targets at a minimum total annual cost. A detailed objective function including total operating costs and investment is considered.The influence of the variation of CO2 reduction targets and the mixing proportion of amines on the total annual cost is analyzed in detail. Numerical results are presented and discussed using different case studies.The results demonstrate that process simulators can be used as a powerful tool not only to simulate but also to optimize the most important design parameters of the post-combustion CO2 capture process. Fil: Rodriguez, Néstor. Universidad Tecnológica Nacional. Facultad Regional Rosario; Argentina Fil: Mussati, Sergio Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; Argentina Fil: Scenna, Nicolas Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; Argentina

In the present paper, the results of an activity performed in the ongoing EU project, CESAR (CO2 Enhanced Separation and Recovery) are presented. In the CESAR project five different baseline power-plants are considered. These consist of two lignite- and two bituminous-coal fired plants while the fifth is fuelled by natural gas. Part of the design work relates to identifying the benefits attainable through appropriate integration of flue-gas cooling to these baseline power-plants. It is shown that the approximate reductions in capture-cost for the studied (optimal) cases are of the order of 20% for the lignite-coal cases, 10% for the bituminous coal cases and 13% for the natural gas case using MEA as solvent. The reductions are basically due to the inclusion of pre-cooling. However, a positive effect of inter-cooling was also found for all the coal cases, while a negative cost effect was found for the natural gas case. For piperazine as solvent the positive effect of cooling was much more pronounced than for MEA and especially the effect of inter-cooling.

A rate-based process model for the reactive absorption of carbon dioxide (CO2) from a gas mixture into an aqueous monoethanolamine (MEA) solution in a packed column is developed. The model is based on the fast second-order kinetics for the CO2–MEA reactions and takes into account the mass transfer resistances. The heat effects associated with the absorption and chemical reaction are included through energy balances in the gas and liquid phases. Appropriate correlations for the key thermodynamic and transport properties and for the gas–liquid mass transfer are incorporated into the model to ensure reliable predictions. The model predictions are validated by simulating a series of experiments conducted in pilot and industrial scale absorption columns with random and structured packings reported in the literature. Comparisons between the simulation results and the experimental data reveal good quality predictions of the gas phase CO2 and MEA concentrations and the liquid temperature along the column height. The sensitivity studies reveal that the correlations for the gas- and liquid-film mass transfer coefficients given by Onda et al. (1968) provide better predictions than the penetration theory of Higbie (1935) and the correlation of Bravo et al. (1985) .