Simulation And Experimental Study On Biogas Fermentation Of Solid Livestock And Poultry Manure

Mixing is an important operation in the process of high-concentration material biogas fermentation.Aiming at the lack of basis for the design of dry anaerobic fermentation stirring equipment and the determination of stirring speed,and the resulting problems of low biogas fermentation efficiency and energy waste,this paper adopts computational fluid dynamics(CFD)to analyze livestock and poultry manure dry biogas fermentation tanks.The internal flow field is studied,and the continuous biogas fermentation experiment is carried out to study the influence of the mechanical stirring intensity of the biogas fermentation process.The specific content is as follows:First,the multiple reference system method is used to simulate the flow field of four different stirring blade types,and the influence of solid content and mechanical stirring intensity on the flow field is explored.By analyzing the speed cloud diagram,the speed distribution and the stirring power,the suitable stirring of the four stirring blades is obtained.It provides a theoretical basis for the selection of mixing blades of livestock and poultry manure dry-type biogas fermentation tanks.Secondly,according to the actual situation,the frame-type stirring blade is selected as the research object,and the influence of different stirring blade diameter and the installation height of the stirring blade on the flow field is simulated and analyzed.After the appropriate stirring blade parameters are selected,the sliding grid method is used to simulate mixing Time,study the influence of monitoring point position and feeding point position on mixing time,and finally evaluate the mixing effect of frametype stirring paddle.Finally,on the basis of the selected frame agitator,the experimental research on the mixing power of dry fermentation of livestock and poultry manure was carried out.Four groups of experiments were carried out without agitation,and the stirring speed was 20 rpm,40rpm,and 60 rpm.The experimental results show that when the mechanical stirring intensity is 20 rpm,40rpm and 60 rpm,the biogas production rate is20.3%,41% and 35% higher than that of the non-stirring condition group,and the methane content is stable at about 70%.In addition,the linear velocity of the CFD simulated stirring paddle is in good agreement with the actual value.The average value of the simulated stirring power is 6.55% lower than the experimental value,and the simulation accuracy is sufficient for use in engineering practice.