Design Of Anaerobic Co-digestion Reactor Monitoring And Control System For Livestock And Poultry Breeding Wastes

The trend of large-scale livestock and poultry farming in China is significant,and environmental pollution caused by farming waste has become a dilemma.The anaerobic co-digestion technology of livestock waste has become the key to resource reclamation.The main problems include firstly the online monitoring and auto-control system does not match the present digestion system.the outmoded control techniques leads to unstable start of the digestion process;second,a vacancy of remote online monitoring and control system required for the use of high level automation processing equipment needs to be filled urgently.At present feedback-controlled digestion system is not successfully developed.Therefore,the anaerobic digestion facilities of large-scale farms generally operate poorly,and the resource reclamation efficiency is low.This paper takes the co-digestion experimental system of livestock and waste as the research object.Based on the existing experiment research,a remote online monitoring reactor control system based on PLC,HMI and configuration software is designed and developed.The main hardware components of the system include:temperature control module,biogas sampling system,biogas component concentration analysis module and remote communication module.The systematic software design includes:PLC programming agitating,heating and temperature constant control;HMIEditor P based on-site on-duty HMI and remote control PC.Developed pilot-scale anaerobic digesters of 100L and2000L have realized operation monitoring,process data collection,digestion status warning and partially feedback auto-control.This paper also analyzes and discusses the effects of multiple waste biomass pretreatment schemes and anaerobic co-digestion ratio and other process schemes,and reports the experimental data and online monitoring data of each stage of digestion.Logistic function was used to fit and analyze the timely digestion status,study the correlation between anaerobic co-digestion process control and treatment effect,and determine the control target and system plan.The Logistic function fit of the cumulative biogas,the increasing function of CH₄ concentration and the decreasing function of CO₂ concentration are all higher than0.98,and it is of great significance to be used to predict the anaerobic digestion trend of the system.Based on the application of MATLAB,Logistic function can be fitted to the biogas gas production data dynamically.Through the fitted dynamic curve set,it is easier to analyze the inflection point of the cumulative biogas production,and the ultimate maximum production,combined with the concentration of CH₄ and CO₂ in the biogas and the operation scenario,can finally achieve dynamic continuous feeding control.The anaerobic co-digestion control system designed and developed in this study has been continuously and stably operated in two reactors of 100L and 2000L pilot scale.During the epidemic the 100L small-scale digestion system located in the campus has achieved more than 90 days of remote online monitoring,automatic data collection,automatic recovery and remote process control.The systems operate stably and reliably,with less maintenance and simple manual operation.They satisfy the requirements of anaerobic co-digestion process control,and achieve the expected control goals of specialized equipment development.