Research On Environment-friendly Vertical Fermenter Control System

With the rapid development of animal husbandry and the increasing scale of animal husbandry in China,the discharge of animal manure is continuously increasing,which brings tremendous pressure to the ecological environment.Fermentation is the main method to treat livestock and poultry manure.Fermentation of livestock and poultry manure in fermentation tank can not only reduce environmental pollution,but also produce organic fertilizer to achieve green development.Traditional fermenter operation is complex,and the adequacy of fermentation and the quality of organic fertilizer depend on the operator's experience.It is difficult for the operator to control accurately.In order to improve the quality of organic fertilizer,it is necessary to improve the control quality of fermentation process.Temperature and humidity are important process parameters in fermentation process.Temperature and humidity control in fermentation tank is an important link in fermentation process,and its control precision directly affects the quality of organic fertilizer.This thesis studies temperature and humidity control method based on PLC as the core by analyzing the control technology of temperature and humidity of fermenter at home and abroad.This thesis takes PLC as the hardware platform,builds human-computer interaction interface,and uses PID neural network decoupling algorithm,and combines with BP neural network control strategy to achieve temperature and humidity control during fermentation.The main work done in this thesis is as follows:(1)Completed the overall design of the organic fertilizer fermenter.Firstly,the process flow of fermenter fermentation is introduced,and the structure of organic fertilizer fermenter and its subsystems were analyzed.Secondly,the corresponding control requirements are determined by analyzing the working process,and hardware selection and software design are completed on this basis.This thesis selects Siemens S7-300 CPU315 as the controller,PT100 as the temperature sensor and ES2-HB-N sensor as the humidity sensor.Thirdly,by analyzing the characteristics of the fermenter fermentation process,the mathematical model of the temperature and humidity of the fermenter with a volume of 45m~3 is derived,and the model parameters are identified by the step response method.(2)The research on temperature and humidity decoupling algorithm and control strategy is completed.There is strong coupling between temperature and humidity during the fermenter process,and the control is difficult.Decoupling is needed to improve the control quality.Firstly,the principle of feedforward compensation decoupling and PID neural network decoupling algorithm is analyzed.The simulation analysis shows that the decoupling response time of PID neural network is fast,which can reduce the coupling between temperature and humidity to a large extent.Although feedforward decoupling can achieve better decoupling effect,the premise is that the precise mathematical model of the controlled object is known,and the mathematical model of temperature and humidity of the organic fertilizer fermenter is difficult to establish.Therefore,the PID neural network decoupling algorithm is selected for decoupling.Secondly,The principle of traditional PID control,BP neural network control and other control strategies are analyzed.Based on the PID neural network decoupling algorithm,the traditional PID control and BP neural network control algorithm are verified by MATLAB simulation development platform.The results show that based on the PID neural network decoupling,the BP neural network control has fast response time,small overshoot,and the output finally reaches steady state.(3)The design of the fermentation tank control system was completed.According to the process requirements and functional requirements analysis of the fermenter,the input and output quantities were determined,and the design of the main circuit and the operation circuit was completed.The PLC software design is completed,including design of main program,initialization program,data acquisition subroutine,temperature and humidity control algorithm subroutine,fault and alarm subroutines and display subroutines.(4)Completed the experimental study on the control system of organic fertilizer fermenter.Firstly,the heating and humidifying device of the fermenter system is determined.Secondly,the design of the human-computer interaction interface is completed,including the interface design of the main interface,the homepage,the flow chart interface,the state monitoring interface,the temperature and humidity curve interface,and the parameter setting interface.Third,the HXC-FJJ02 model fermenter system is constructed,and the control system is trial-produced and the modules are separately debugged.Fourthly,the cow manure is used as the fermented material,and the system test is carried out.The test results are analyzed.The results showed that the PID neural network decoupling and BP neural network control algorithm can meet system design requirements.The fermenter temperature and humidity control system studied in this thesis has the advantages of high control precision,friendly human-computer interaction and low cost,which provides a guarantee for the sustainable and healthy development of animal husbandry and has broad market prospects.