| The conventional reactive distillation column (RDC-SRS) which has only one reactive section for reaction can meet the needs of reaction and distillation of the general system in most cases. And compared to the system having reactor and distillation apparatus has the intensification advantages of small investment and low energy consumption. However, it will face the difficult of coordinating which results the deterioration of the system performance when it is applied in two-stage consecutive reversible reaction system. So a novel reactive distillation column with double reactive sections (RDC-DRS) which features more design degrees of freedom allows careful coordination of two reactions and has lower energy consumption as compared with the reactive distillation column with a single reactive section (RDC-SRS) was proposed. However, its dynamic controllability has hardly been studied.In the current work, an illustrative example, the process of producing diethyl carbonate via two-stage consecutive reversible reaction is chosen to evaluate the dynamic performance of the RDC-DRS. One concentration control strategy is proposed through analyzing the manipulated variables and the controlled variables of RDC-DRS. The same control strategy is applied to RDC-SRS.In the concentration control strategy, the bottom concentration control loop is used to guarantee the quality of main products of diethyl carbonate, the top concentration control loop is used to maintain the conversion of reactant, a cascade control loop of the sensitive stage and the feed flow rate is used to ensure the stoichiometric balance between the reactants. Simulation results show that the RDC-DRS has good capability of suppressing disturbances in the face of the feed flow and feed composition disturbances. As compared with the RDC-SRS, the RDC-DRS has better dynamic controllability. The same conclusion is reached in the subsequent temperature control strategy. |
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