| The process of producing diethyl oxalate and oxalic acid by CO coupling reaction in gaseous phase was one of the most important projects of C1 chemical technology, due to its technical predominance. Based on the results from the experiments, it was necessary to study the nonlinear properties of the reaction system in the context of industrial process scale-up, control and optimization. Unluckily, no report related to nonlinear behavior analysis for the system presented up to now. In the thesis, the analysis for this complex reaction system was carried out in detail.According to the characteristic of the system, the scheme served as the foundation for the nonlinear analysis was proposed, on which the whole system was simplified as two parts -CO coupling system and Regeneration system. Then the dynamics models were also set up respectively.On the study of CO coupling system, the finite difference method and the numerical continuation technique were used to carry out the bifurcation analysis in some detail. The static bifurcation phenomena was observed in some cases, whereas there no Hopf bifurcation points was found for all the parameters chosen in this paper. It was shown that the system had at most three steady state solutions. Meanwhile, the influence of the dimensionless numbers such as Pe1, Da1, B1,β1, x2c,γ, Nc were investigated separately, and the results were illustrated in the (Da1-Pe) and (B1-Pe) plane. The parameter study demonstrated that the axial mass and heat feedback was the main factor resulting in multiple steady states. For this system the static bifurcation occurred only when the value of Pe was much smaller. Moreover, the study provided a practical example for the reaction with the kinetics expression in a fixed-bed reactor.Based on the one-dimensional plug flow reactor model, the parametric sensitivity for CO-coupling system was either discussed. The analysis approach for the reaction system with kinetics was used for reference. The formulae for the temperature of critical hot spot were derived theoretically and the numerical procedure for evaluating the temperature of critical hot spot and the critical inlet concentration of CO was developed. And The effects of operation conditions such as the temperature of inlet and heat-exchange medium, heat-exchange flow and feeding ratio on the temperature of critical hotspots and the critical inlet concentration were also examined, and the regions of parametric sensitivity in the reactor parameter space were also illustrated for various values of the involved parameters. Additionally, the temperature of hotspot and its position were obtained by solving the equations of the locus of hotspots together with the reactor model. The influence of parameter on the hot spot was discussed with co/counter current and constant wall temperature of heat exchange medium, it was shown that cocurrent flow exhibited good performance compared with countercurrent flow.With respect to the regeneration system, both the theory and analysis methods for a single first order reaction carried out in CSTR proposed by Uppal and the continuation technique was applied to the regeneration system (gas-liquid reactor). By the theorical analysis, the necessary and sufficient condition for multiple steady states was obtained. The parameter space was divided into seven regions, in which the nonlinear behavior performed was discussed in detail. By the numerical evaluation, the multiple steady states zone was constructed. At the same time, the influence of various values of the parameters involved in regeneration system on the multiple zones on different parametric plane was examined as well. Actually, the method and some conclusion mentioned in the analysis of regeneration system could easily be applied to the non-adiabatic one/two phase CSTR system with reaction kinetics .
|
PDF Full Text Request