Evaluation And Optimization Of Periodic Operation Of Chemical Reaction Process Based On Nonlinear Output Frequency Response Functions

Periodic operation of chemical reaction is a technology to improve system performance by using reaction nonlinearity.Its evaluation and optimization is still the key problem to be solved in industrial application.It is time-consuming and expensive to determine whether periodic operation is beneficial or not and to select the operating conditions that maximize the process performance.NFR method relies on the mechanism modeling of the system,and it is difficult to derive the higher-order frequency response functions.For the complex chemical reaction process,the mechanism modeling is difficult to realize,which brings difficulties to its wide application in the industrial field.In this paper,a evaluation method of univariate periodic operation and multivariable synchronous periodic operation based on NOFRFs was proposed,and the method was used to evaluate the univariate periodic operation and multivariable synchronous periodic operation of non isothermal CSTR.Firstly,according to the input and output data of the system,the order of NOFRFs contributed by each single variable was determined,and the single variable periodic operation was evaluated by the system performance index.On this basis,the periodic operation of multivariable synchronization was evaluated to determine the optimal phase difference to maximize the conversion rate.Finally,the order NOFRFs of the cross term of multivariable synchronous operation were determined.The simulation results show that the proposed method is better than the traditional NFR method and improves the accuracy of periodic operation evaluation.At the same time,the optimal design was carried out under the allowable process constraints,which significantly improved the conversion of reactants.In order to further verify the effectiveness of NOFRFs method in the evaluation of complex chemical reaction process,this paper used the NOFRFs method to evaluate the system performance improvement of the univariate periodic operation and multivariable synchronous periodic operation of the flow-rate of the reaction stream and the temperature of the cooling fluid in biodiesel reaction process.The results show that NOFRFs could effectively evaluate the continuous biodiesel reaction process regardless of the single variable or multivariable periodic operation,which provides a reference for the evaluation and optimization of periodic operation of other types of chemical reaction process.