Design And Thermal Performance Study Of Biogas Heating System

At present,the warming and insulation technology of biogas digester is a research problem and focus on the field of biogas science.At the same time,the influence of stirring device and heat exchange device on fermentation is crucial.It is very important to find a set of biogas warming system that can satisfy the perennial temperature fermentation.The purpose of this study is to overcome the seasonal and regional restrictions of biogas fermentation and achieve year-round temperature fermentation,and improve the degree of solid-liquid mixing,heating rate and uniformity by optimizing key components and operating parameters,so as to provide a basis for the optimization of key components and provide references for subsequent research and practical engineering applications.This thesis takes biogas warming system as the research object,and the research contents are as follows:(1)The composite heating system of solar energy and power generation waste heat is designed to heat biogas fermenter.Taking a pig farm with an annual output of 2,500 head as the research object,the equipment parameter calculation and structural selection of the system are carried out.When the solar heat collection area is finally determined to be14m~2,the system can meet the heating demand of the fermenter in the coldest month.(2)The mass transfer process in the fermenter was simulated by using FLUENT software from the three aspects of the structure parameters,installation height and operation parameters of the stirring device,the influence of these factors on the mass transfer process was analyzed,and the best parameters were selected according to the mass transfer effect.The results show that the best mixing performance is achieved when the stirring speed is90rpm,the blade deflection Angle is 30°and the blade height from the bottom is 1m.(3)Based on the optimal structure and operation parameters of the stirring paddle,the flow heat transfer process in the tank under different inlet and outlet locations of circulating water,different circulating water temperature and different circulating water velocity was further simulated,and the heating effect was investigated according to the temperature field,the change of the average temperature of fermentation liquid and the heating rate.The results show that the comprehensive heating performance is the best when the circulating water flows up and down,the circulating water temperature is 60℃and the flow rate is 0.075m/s.