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Modelling and identification for carbon dioxide post-combustion capture by amines supported on solid sorbents

pubblicazioni - Articolo

Modelling and identification for carbon dioxide post-combustion capture by amines supported on solid sorbents

La memoria descrive un modello matematico dinamico del processo di cattura post-combustione della CO2 con sorbente solido e la sua validazione con dati sperimentali di laboratorio.

Chemical adsorption by solid sorbents appears as one of the technologically most promising and less energy intensive processes for post-combustion CO 2 capture in coal-fired power plants. Attention, here, is devoted to fixed-bed reactors where adsorption is carried out by amine supported on pelleted solid substrates. A first- principle dynamical model of the ad-de-sorption process has been worked out, with reference to a laboratory- scale diabatic tubular reactor. This model will be a useful support tool for design and verification of a pre- industrial scale pilot plant currently under study at ERSE. The cylindric volume has been divided into smaller volumes, or strips, along its axial coordinate, and mass and heat exchange between bulk gas and pellets has been described by means of lumped-parameter conservation equations. An average equivalent spherical pellet has been associated to each strip and distributed-parameter mass, energy and momentum conservation equations have been written along its radial coordinate, with particular care for diffusion processes and for surface convective processes; the kinetic- chemical mechanisms of adsorption and desorption in the porous material have been also described in detail, and activated site conservation equations are included in the model. Simulations have been carried out in the Matlab-Simulink environment, by building suitable “S-functions” in C++ language. The main unknown parameters, i.e. the CO 2 adsorption, desorption and diffusion coefficients, have been estimated not only from literature data, but also thanks to dynamical data from a laboratory-scale reactor, operating in a Temperature Swing Adsorption mode. For the identification procedure, standard least-square based algorithms have been employed.

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