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A Study On Simulation And Optimization Of Naphtha Catalytic Reforming Processes

Posted on:2005-08-24Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y Y HuFull Text:PDF
GTID:1118360122471274Subject:Control Science and Engineering
Abstract/Summary:PDF Full Text Request
The process simulation and optimization technology is widely applied to the process industry and brings large profits for related plants and companies. Especially the special simulation and optimization software on complex catalytic reaction process is more important and pursued by the corporations and institutes involved.In this dissertation, the reaction kinetics, modeling and optimization of naphtha catalytic reforming process, which is a very important process in hydrocarbon processing industry for octane improvement or as sources of aromatics and hydrogen, is studied. The objective of this dissertation is to develop the simulation and optimization software with good features of easy using and complete functions and to apply to commercial naphtha catalytic reforming processes. In this dissertation, the main contributions are as follows.1. The kinetics of naphtha catalytic reforming reactions are studied and a kinetics-based reaction model with only 17 lumps consisting of PNA (Paraffins, Naphthenes and Aromatics) and 17 reactions is developed according to the character and applying conditions of domestic industrial reformers. The lumping scheme and reaction network of this model largely decrease the complexity of model and demand for detailed component analysis, so it is easy to apply this model to the commercial units. The catalyst coking model with average activation function of catalyst is presented. The heat transferring model of furnace and gas-liquid balancing separation model are also described here.2. The calculation methods of physical and chemical properties of lumps are presented and the model kinetic parameters are benchmarked with plant data. The procedure of parameter estimation is done by minimization of the sum of the squares of the deviations between plant and predicted values of key variables. In order to decrease the difficulty of parameters estimation, a new parameter estimation method is proposed and the estimated parameters are drastically decreased from 68 to 17. A dynamic catalyst coking model and multi-variant linear regression model are used to estimate the parameters of catalyst coking model. Especially parameter estimation algorithms are discussed and a new method based on BFGS and differential precise linear searching is proposed tosolve the unconstrained optimization problem successfully deriving from parameter estimation. This new algorithm looses the strict demand for the initial point and also avoids the inverse operation of Jacobin matrix.3. A new numerical algorithm integrating a quasi-analytic numerical algorithm with the Gear numerical algorithm is used to solve the ordinary differential equations with stiff problem. To accelerate the solving of ODE, the optimum step method is introduced into the composite numerical algorithm.4. Process optimization based on kinetic model is studied. The solving of process optimization problem with process constraints is performed by SQP. And the sensitiveness analysis of optimization results to the kinetic parameter errors is also given.5. A dynamic model of catalytic reforming process is described and the dynamics of this process are studied. The dynamic model is a typical nonlinear distributed-parameter system with high dimension about19XN X4, where N is the section number in one reformer. Method of lines is adopted to reduce these partial differetial equations (PDEs) into N lumped-parameter ordinary differetial equations (ODEs) solved by numerical algorithm. The responses with the step or impulse disturbances of key process variables such as reaction temperature, pressure and feed charge are given and the agreements between dynamic model calculation and static model calculation are satisfactory.6. The process simulation and optimization software with Graphic User Interface (GUI) is developed with MATLAB language based on MATLAB platform. With this software, the model parameters are benchmarked with plant data and the simulation results of the model validated for...
Keywords/Search Tags:Catalytic reforming, Kinetic model, Process simulation, Process optimization, Dynamic modeling, Parameter estimation, BFGS, SQP, Numerical algorithm, MATLAB
PDF Full Text Request
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