Reduced-order modeling of carbon dioxide absorption and desorption with potassium carbonate promoted by piperazine

Carbon dioxide emitted from the power plants may be removed in an absorber-stripper unit, where CO2 mass transfer enhanced by chemical reactions occurs. The mass transfer enhancement factor can be found accurately once we find the CO2 profile in the liquid film around a packing material. However, it costs a tremendous amount of computer time to solve governing diffusion–reaction equations for the relevant chemical species at each grid point of the packed bed to determine the enhancement factor accurately. Therefore, in the traditional models of packed bed, one adopts an approximate enhancement factor found from a simple model. In the present work, we employ the Karhunen–Loève Galerkin (KLG) method for the solution of the diffusion–reaction equations describing the CO2 absorption with potassium carbonate promoted by piperazine in the liquid film. With the KLG method, the computational time for the diffusion–reaction equations is reduced drastically and the rigorous model for the enhancement factor can be adopted in the industrial packed beds. The resulting reduced order model is found to predict the concentration profiles of chemical species accurately. It shall be adopted in the multiscale model for a packed bed, where the macro scale describes the overall geometry of the packed bed and the micro scale describes the transport and reaction in the thin liquid film around a packing at an arbitrary macro location in the bed.