Dynamic modelling of CO2 absorption for post combustion capture in coal-fired power plants

Abstract

Power generation from fossil fuel-fired power plants is the largest single source of CO 2 emissions. Post combustion capture via chemical absorption is viewed as the most mature CO 2 capture technique. This paper presents a study of the postcombustion CO 2 capture with monoethanolamine (MEA) based on dynamic modelling of the process. The aims of the project were to compare two different approaches (the equilibrium-based approach versus the rate-based approach) in modelling the absorber dynamically and to understand the dynamic behaviour of the absorber during part load operation and with disturbances from the stripper. A powerful modelling and simulation tool gPROMS was chosen to implement the proposed work. The study indicates that the rate-based model gives a better prediction of the chemical absorption process than the equilibrium-based model. The dynamic simulation of the absorber indicates normal absorber column operation could be maintained during part load operation by maintaining the ratio of the flow rates of the lean solvent and flue gas to the absorber. Disturbances in the CO 2 loading of the lean solvent to the absorber significantly affect absorber performance. Further work will extend the dynamic modelling to the stripper for whole plant analyses.

Current status and future development of solvent-based carbon capture

“…Dynamic models of stand-alone absorber (Posch and Haider 2013;Kvamsdal et al 2009;Kvamsdal and Rochelle 2008;Khan et al 2011;Lawal et al 2009a) and stand-alone stripper (Lawal et al 2009b;Zaii et al 2009) which are the main components of the PCC process based on chemical absorption are available in literature. The dynamic models of the complete process including the absorber and stripper are also available (Lawal et al 2010;Harun et al 2011;Gáspár and Cormoş 2011;MacDowell et al 2013;Flø et al 2015).…”

Dynamic simulation of MEA absorption process for CO2 capture from power plants

“…Lawal et al (2009a) modelled a standalone absorber and used the same pilot plant process to enable a comparison with Kvamsdal's work (Kvamsdal et al, 2009). Both equilibrium and rate-based packed column models were developed using the Radfrac column model in Aspen…”

“…That is, the integration between absorber and stripper, which represent the complete MEA absorption process, was not considered in those studies. Lawal et al (2010) extended their previous models (Lawal et al, 2009a;Lawal et al, 2009b) to consider the complete MEA absorption process by integrating both absorber and stripper with the recycle stream. The analysis of the dynamic response with respect to changes in flue gas flow rate and compositions, and reboiler heat duty were discussed.…”

“…The assumption of phase equilibrium for the contacting liquid and gas phases is inadequate to describe the static and dynamic behaviour of reactive absorption units. A study by Lawal et al (2009a) has shown that the rate-based model provides more accurate descriptions for these process units. Thus, the rate-based approach is more suitable for the present application and was the method applied in this work.…”

Process simulation and analysis of carbon capture with an aqueous mixture of ionic liquid and monoethanolamine solvent

“…Secondly, existing PCC models with IL-based solvents are developed using equilibrium-based mass transfer approach. Rate-based mass transfer approach gives more accurate prediction of the process conditions (Peng et al 2003;Lawal et al 2009). Finally, none of the studies have investigated the implications of varying the IL concentration in the mixed IL and alkanolamine solvent.…”