Cyclic Automation of a Plant for the Removal of CO2 from Biogas

An upgrading process to obtain biomethane from biogas is studied, consisting of carbon dioxide removal by an amine-based pelleted solid sorbent inside a fixed-bed tubular reactor. The amine catalyst undergoes a saturation effect, so that a regeneration stage is necessary. In order to ensure continuous biomethane production, the plant automation requires a set of reactors working in parallel. This way, while a reactor is in the adsorption stage, another one is in the regeneration stage. The duration of the stages is such that three reactors at least are needed. Overall, this leads to a cyclic control system. In this paper we develop a dynamic model of the batch process, based on mass, energy and momentum conservation equations and on algebraic constitutive relations. From the initial partial differential equation model, a lumped parameter description is worked out, leading to a nonlinear system with 280 state variables. Such model is used to understand the adsorption/desorption process in detail and then design a cyclic control structure. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.