Development Of Dynamic Simulation System For Reactors

Reactor is significant in the chemical industries and the efficiency and stability of the reactor will affect its upstream and downstream processing units.Because of complexity and terrible reaction condition,some key parameters(such as temperature,concentration distribution of the reactant and product)can't be on-line measured.In addition,there exists disturbance in the industrial process and it will lead to lower efficiency and state deviation of the reactor.The lower efficiency and state deviation may cause the whole process shutdown or explosion of the reactor because it is difficult to identify the state of the reactor due to lack of measurement of key parameters.Currently,simulation software such as Aspen plus,Hysys,and PRO ? are widely used in steady-state simulation,process design,and process optimization.However,there is some limitation for the commercial software in on-line simulation,especially for complex reaction processes.Hence,it is meaningful to develop dynamic simulation system for reactors.Firstly,the dynamic model of ideal reactor is analyzed and its solution method is investigated.The result shows that dynamic model of the continuous stirred tank reactor(CSTR)can be solved easily because it is described by a series of ordinary differential equations(ODEs).However,the dynamic model of piston flow reactor(PFR)is consisted of a series of partial differential equations(PDEs)and the number of the variables is greater than the number of equations,so the model can't be solved directly.For the case of gaseous feedstock in the PFR,the concentration of the gaseous component is expressed as the function of molar flow and temperature according to the state equation.Therefore,the dynamic model of the reactor can be solved by finite difference method.To valid the method,the results of the conventional method is compared with the results of the improved method.The results show that the improved method is effective for solving the dynamic model of the PFR.Secondly,development of the dynamic simulation system is introduced.The function of the dynamic simulation system includes graphic modeling,parameter input,saving and loading of model,simulation and calculation.Based on the idea of object oriented and modular programming,the dynamic simulation system is divided into unit equipment,stream,graphic modeling,navigator,data management,model solver,and data saving modular.The framework of the different modular is introduced.Finally,three cases are applied in the simulation system.Among them,the cases are CSTR,liquid feedstock of PFR(LPFR),and gaseous feedstock of PFR(GPFR),respectively.By comparing the simulation results with the results of literatures,the effectiveness of the simulation system is validated.