Modelagem, simulação e controle do processo de degradação de tricloroamina (NCl3) na produção de cloro (Cl2) eletrolítico.

Abstract

Chemical reactions, with explosion risk, performed in industrial plants should be carefully controlled to prevent the obviously undesirable consequences of an incorrect operation. Controlling chemical processes, means to work with systems in which the controlled variables and manipulated variables usually present restrictions, besides strong interactions. A control strategy was developed for a reboiler coupled with an absorption column, containing recycles, located in a commercial C12 production plant. A chemical reaction that presents restriction to the maximum operating temperature (high explosion risk) happens in the first equipment and therefore should be carefully controlled. A theoretical model, in the stationary state for the coupled system, was generated in the commercial Simulator Aspen Plus™, from which a dynamic model was developed in the commercial Simulator Aspen Dynamics™, obtaining the transfer functions involving controlled variables and manipulated variables. A plant test was performed with the purpose of identifying the system, to proceed with the adaptation of the proposed model. Systems coupled with recycle present unusual peculiarities when a high magnitude of load disturbance is present in the main current of the global industrial process, leading to additional difficulties to obtain the control objectives requested by the process. A detailed description of the process of commercial production of CI2 was presented, as well as a brief revision of the literature existent on the control strategies involving coupled systems, from which the manipulated and controlled variables were defíned. After the analysis of stability in closed mesh, several techniques of the controller's syntony were accomplished and compared. Dynamic simulations were developed and the results were discussed to identify the best control strategy. The conclusion was that the several methods presented satisfactory results towards the control objectives, making it possible their implementation in the industrial plant. Other recommendations, suggesting alterations of the industrial project were proposed with the intention o f optimizing the performance of the system in study.