Evaluation of CO2 Capture Using Aqueous Ammonia Solution in a Flexible Operation Scenario

Carbon dioxide has the largest contribution to the greenhouse effect among all of the greenhouse gases and its emission levels have become a big concern in the last decades. Carbon Capture and Storage (CCS) technologies aim to curb CO2 emissions not only from the power generation but also from other energy-intensive sectors. Among the various approaches to separate CO2 from flue gas, the absorption-based CO2 capture technology is known to be the most practical method mainly due to its technical maturity and large gas treating capacity. The power plants are required to be operated in dynamic scenario, due to the timely variation of the grid demand. Dynamic simulation is a viable solution to identify any operational issue at transient conditions for the integration of CO2 capture into power plants. In this paper, a rigorous dynamic rate-based model for CO2 absorption using aqueous ammonia in a packed column has been developed. The main model equations are developed by applying the overall mass, component mass and energy balances for the liquid and vapour phases, respectively. The model also considers mass and heat transfer resistance in the liquid and gas phase, hydrodynamics and column properties of the whole absorption system. The kinetic model has significant impact on the simulation and analysis of absorber. The partial differential equations of model have been solved in Matlab/Simulink, the model has been validated with data collected from pilot plant, published in literature. The developed model is used to analyse the species concentration profile, temperature profile, mass transfer rate and coefficient in the gas and liquid phase along the packing height. In order to analyse the capability of the model to predict the effect of the operating conditions and the disturbances from the up-stream power plant on the CO2 capture plant operation a dynamic simulations were performed. Also, the evaluations of various operation conditions for optimization of technical indicators of CO2 capture were done.