Research On Intelligent Control System For Dry Biogas Fermentation

Biogas dry fermentation,emerging as a prominent technique divergent from the wet fermentation,solidified its significance in biomass domain by its advantages such as low power and water consumption as well as simpler tailing treatment etc.Varied researches and results are implemented and obtained within the theme.The investigation carried out herein incorporated four aspects,namely the optimization of fermentation equipment,the control algorithm of fermentation temperature,the control strategy of pH value,and the hardware and software designing for the control system for the biogas dry fermentation.The main research work and results of this thesis are as follows:(1)In order to mitigate the effect of mixing difficulty of solid fermentation,double helical ribbon agitator was introduced;the mixing performance of the stirrer in solid fermentation was simulated by the Fluent software.In order to solve the problem of large thermal inertia of fermentation heating device,the hot water exchange system was put forward.A new multi-point temperature detection device was proposed to tackle the difficult problem of detecting multi-point fermentation temperature.(2)The buffer capacity equation,together with the acid-base neutralization PH value output equation,was deduced through the theoretical analysis of the pH value control process of biogas dry fermentation,which manifests validity through experiment verifications.Starting from the derived theory,the PH value control algorithm based on piecewise predictive fuzzy control was developed.(3)According to the heat transfer equation of the fermentation heating system,the transfer function of the heating system was deducted.The segmented temperature control algorithm was developed,which consists of two parts: BP neural networks PID Control for biogas dry fermentation temperature system based on particle swarm optimization and temperature compensation algorithm.(4)The hardware and software of intelligent control system were designed,of which the upper computer interface was built by LabVIEW software,and the lower computer was the ARM9 platform based on embedded Linux system.According to the requirements of temperature detection device,the multi-channel temperature detection module circuit with ZigBee wireless transmission and battery power supply was designed.The validity of fermentation temperature and PH value control algorithm was proved by biogas dry fermentation experiments.