Research On Monitoring And Control Of Anaerobic Dry Fermentation Based On PLC

Anaerobic dry fermentation technology is an anaerobic fermentation technology with a total solid content(TS)of 20%to 40%.Compared with wet anaerobic fermentation,it is widely concerned in the research field with the advantages of water saving,small amount of biogas slurry production,easy in increasing temperature and heat preservation,and low cost.It has become one of the important technologies for the treatment of biomass solid waste.PLC(Programmable Logic Controller)not only has the characteristics of powerful functions,small size,low energy consumption,but also high reliability,strong anti-interference ability,and supports secondary software development.PLC has more research on the automatic control of wet biogas fermentation engineering,and less reports on dry anaerobic fermentation control.This paper uses agricultural biomass wastes such as straw and livestock manure as raw materials,through the dry fermentation process parameter optimization test,the secondary development of PLC configuration software,and the commissioning of the sequencing batch pilot fermentation system,which is a large-scale anaerobic fermentation biogas project PLC Automated monitoring and control technology provides theoretical and data support.The main research work is as follows:(1)Through single factor and orthogonal experiments,the best process parameters of dry anaerobic fermentation were obtained:the ratio of cow dung to straw is 4:1,the fermentation temperature were 35?,p H 6.9,and the amount of biogas slurry sprayed4 times a day.Each time 100m L,the maximum gas production at this time were276m L.Dry fermentation control parameters:temperature is 33?35?,p H is 6.5?7.5,ORP is-300?-350m V,methane concentration between operations were 1%?2%,biogas liquid level were 300?400m L,pressure 102?105k Pa.(2)According to the overall design content and its functions,the anaerobic fermentation system control plan was determined,and the PLC configuration software was carried out for host computer logic programming and secondary development to realize the real-time display of process parameters,data storage and trend chart generation.Programming and controlling the linkage logic of analog input(fermentation temperature T,methane concentration%,liquid level H,pressure P),digital output(water pump,exhaust device,feed pump,pressure relief device)and alarm device(a,b)was focused on.Through the communication protocol,the WIN CC of the upper computer and the control of the mobile phone were synchronized to realize the targeted monitoring and control of the anaerobic dry fermentation system.(3)The commissioning operation of PLC monitoring and control of the 5m~3 anaerobic dry fermentation system was mainly carried out.After 1 month of data monitoring,compared with manual testing,the temperature control accuracy were>97%,the methane concentration monitoring accuracy were>91.2%,and the PLC control accuracy of the analog input parameters is more than 95%.It can better meet the requirements of accuracy,reliability and easy maintenance of the pilot test system,and realize the rapid,efficient and stable gas production of the system.