Thermal balance analysis of northern large-scale biogas generating system based on system dynamics

Aiming at a large-scale biogas generating system in Heilongjiang Province, the energy balance of demand and supply was studied by the methods of system dynamics and finite element analysis of thermal balance, and some key parameters in course of operation were determined. The results showed that the heat loss proportion of the transfer heat of the digester, the evaporation of water, the extracted biogas and the pipelines were 85.59%-90.22%、2.05%-8.42%、3.93%-4.78%、2.06%-2.96%, respectively. The temperatures of mixing hot water were 53℃ from June to August and 65℃ at other months by the heat requirement calculation of heating fermentative materials. The heat requirement of heating fermentative materials made up 73.13%-87.91% of the total heat requirement. The mean heating time of maintaining 35℃ of digester was determined by the heat loss analysis of pipelines. It was determined by the energy balance analysis of demand and supply of the total fermentative system that the system could realize yearly continuous running using the recovery surplus heat of biogas generation. The research laid the theoretic foundation for the application and expansion of large-scale biogas project in northern high-cold region.