Dynamic modelling and validation of pre-combustion CO2 absorption based on a pilot plant at the Buggenum IGCC power station

• Dynamic modelling and validation of pre-combustion CO2 absorption unit presented.
• Physical absorption of CO2 modelled by well-tuned, equilibrium-based absorber model.
• Model validation by means of transient experimental data generated at pilot plant.
• Model predictions satisfactorily reproduce the dynamic performance.

Based on the increasing concern about human-induced global warming, it is expected that constraints on carbon emissions will be much stricter in the future. Integrated gasification combined cycle (IGCC) power plants are an option in the attempt to mitigate the effect of CO2 emissions, because they can be fuelled or co-fuelled with biomass, but also, very importantly, because they can be equipped with pre-combustion CO2 capture units. Moreover, the rapidly growing share of electricity produced by converting renewable energy sources demands for more flexible operation of future IGCC plants in order to compensate for inherently intermittent operation of wind and solar power plants. The CO2 capture unit should therefore be able to follow the dynamic operation of the power plant, and, at the same time, meet environmental targets in terms of CO2 removal. In order to investigate and improve the transient performance of such complex systems, dynamic process simulations performed with accurate physically based models are essential. This paper presents the development and validation of the dynamic model of the absorption and solvent regeneration unit as part of a pre-combustion CO2 capture system, with focus on the absorber column model. The models are implemented into an open source software library following an object-oriented, equation-based modelling approach using the Modelica language. The models are validated by comparison against two sets of transient experimental data generated at the CO2 capture pilot plant realized and operated at the Buggenum IGCC power station in the Netherlands. The model predictions satisfactorily reproduce the dynamic performance of the pilot plant considering the main process variables, such as pressures, flow rates and compositions. One of the results of this work is that, in case of physical absorption of CO2 a well-tuned, equilibrium-based absorber model is able to accurately predict transient operation. The validated process models enable process and control system design aiming at improvement of transient performance of the pre-combustion capture unit.