| Straw extrusion extrusion equipment is an important pretreatment machinery for improving straw fermentation to produce biogas.Stable temperature is one of the preconditions to ensure the quality of extrusion extrusion products.In the extrusion process,the straw has contact friction,resulting in a large temperature overshoot and low robustness in the extrusion process.In the process of straw being extruded by screw,the parameters of heat transfer model will change due to unknown interference factors.When the equipment aging or equipment wear,temperature control will also be affected,which will make the extrusion quality can not be guaranteed.So it is very important to study the temperature control system of extruding equipment for straw extruding.Therefore,this thesis designs three control algorithms to improve the control performance of the system.This topic to straw extrusion machine as the research object,the study of the characteristics of equipment and technology,the application of Box-Behnken response surface method to research the extrusion process parameters influence on straw puffing quality,is the biggest factor that affecting extrusion temperature,constant temperature requirements for temperature control system,and through the analysis of regression equation obtained by the optimal process parameters.In order to heat straw to the theoretical temperature under the optimal process,the influence of heating power on the material temperature field in the extrusion section was studied,and the lowest heating power satisfying the requirements was selected to reduce energy consumption.Aiming at the problem that the temperature overshoot of extruding equipment is large in the experimental process,three temperature control strategies based on PID,fuzzy PID and Smith fuzzy PID are proposed.The mathematical model of the heating system of extruding equipment is built by step response test.The control performance of the three control strategies is predicted by MATLAB Simulink module.The results show that the fuzzy PID with Smith compensation control can obviously improve the overshoot and anti-interference performance of the heating system. |
