Research On Temperature Field Control Of Controllable High Temperature Prepyrolysis Unit

For a distributed parameter system with large time-delay and large inertia of the combustion state of pulverized coal in the axial space and its internal temperature field distribution,it has the distributed characteristics of time-space coupling and the infinite-dimensional characteristics of highly nonlinear systems.,Various uncertain disturbances in the control process and detection components in the system,such as the number of sensors and other influencing factors,all increase the difficulty of building the model.Therefore the partial differential equations used to describe the combustion process cannot be directly used for predictive models.In this paper,aiming at a pulverized coal internal combustion burner with a cylindrical axial structure as the practical application object,and controlling the temperature field inside the burner through the control of the primary air as the control mechanism,a distributed parameter system based on wavelet collocation is proposed.The scale predictive model building method is combined with model predictive control to solve the problem of internal temperature field control of such pulverized coal burners.The main research work of this paper is:First,the partial differential equation model of pulverized coal combustion inside the internal combustion burner is deduced based on the law of energy conservation,the law of component conservation and the law of mass conservation.The model is a parabolic model.And according to the combustion model and the experimental data measured by the internal combustion burner mechanism test bench,the combustion characteristics of the pulverized coal dispersion medium in the internal pyrolysis space and the combustion mechanism of pulverized coal are analyzed,and the internal combustion characteristics and influencing factors of the system on temperature are obtained.According to the method of collocation of points by wavelet,a modeling method of a kind of distributed parameter system is proposed.Space basis function Shonnon-Gabor wavelet is selected as the space basis function of the model,and the widely used forward Euler method is used to discretize space and time variables to obtain a linear discrete model of the system.Secondly,according to the theory of space-time decomposition,the linear system discrete temperature model function is reduced and decomposed to obtain the mathematical model of the temperature field.Afterwards,the forward difference of the mathematical model is used to obtain the prediction model of the single point of the temperature field.Combining the input parameters measured by the field experiment and the temperature data detected by the temperature sensor,the results of the prediction model are corrected,and the results of the simulation experiment data under different wavelet scales are compared to illustrate the effectiveness of the system method.Finally,according to the nonlinear parabolic system of the internal combustion burner,the first-order and second-order spatial partial derivatives are respectively projected on the Shonnon-Gabor wavelet,and a low-order model of the internal temperature field of the self-sustaining burner is obtained.A nonlinear predictive controller is designed and simulated in MATLAB.By comparing the simulation results of the test,the temperature field distribution formed by the combustion of pulverized coal in the internal combustion burner is analyzed,and the control of the primary air realizes the prediction and control of the internal temperature field of the burner.