Steady state analysis of the flow continuous stirred tank reactor on instance exothermic dimerization reaction

Objectives. Due to the complexity of their behavior, chemical process flowsheets are characterized by steady state multiplicity, in other words, the presence of multiple steady state operating modes having the same set of parameters. The steady states differ from each other in terms of their reagent conversion, selectivity, product flow composition, and stability. Therefore, in order to be able to identify the steady state having optimal technological indicators, the objective of searching all steady states of a chemical process flowsheet is relevant. The aim of the study is to research all possible steady states for a continuous stirred tank reactor (CTSR) according to the exothermic dimerization reaction and investigate the influence of different operation parameters on the technological indicators of found states.

Methods. Mathematical simulations of material and energy balance equations for reactor were used. The quantity of steady states was estimated by the number of energy balance discrepancy function intersection with the Ox axis. The Newton method in Microsoft Excel was used to solve nonlinear material balance equations of the reactor. The initial value of productivity was in range from zero to feed rate value of reagent of 100 kmol/h.

Results. It is shown that up to three steady states may exist for the reactor in dependence on the reaction volume, composition, and temperature feed flow, as well as the heat carrier flow rate. The results of this study correspond with earlier obtained results, which were obtained for irreversible reactions in adiabatic conditions. These states differ in productivity, internal reactor temperature, and stability. Steady state stability analysis of small parameter deviations was carried out. The analysis demonstrated that real characteristic values are in all found steady states of the reactor. Therefore, no oscillations in stable steady states of reactor and asymptotical operating time dependencies are implemented.

Conclusions. The technique of steady state analysis of a continuous stirred tank reactor developed over the course of this study, which reveals all steady states of the reactor with heat exchange, can be used to perform steady state analysis of recycled chemical process flowsheets, including continuous stirred tank reactors and separation blocks.

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