SELECTION OF MATERIALS AND FORMULATION OF MATHEMATICAL EQUATIONS FOR THE DESIGN AND CONSTRUCTION OF A METAL BIOGAS PLANT FOR RESEARCH PURPOSES

Abstract

 

Abstract: A mobile biogas plant was designed, constructed and tested for experimental studies following the standard techniques in literatures. The plant was constructed using mild steel AISI 1020 grade material while biodegradable wastes (cattle, pig, poultry and human) were used as the design parameters. However, the research work was primarily conducted to come up with mathematical detail design of biogas energy production system to get clean biogas for domestic use. This involves the development and analyses of the components and body shapes to have a portable and movable system. The major components of the plant are biodigester, biogas storage tank, compressor, electric motor, filter, connecting rubber pipes and steel frame. The physical properties (such as pressure, mass, density, stress, force and volume) of both the steel and biodegradable wastes were analyzed and evaluated. The volume of biogas estimated as 0.0270 m³/day was considered as main parameter for the design of metal biodigester and biogas storage tank. The quantity of waste for cattle, pig, poultry and human was calculated as 1.080, 0.600, 0.360 and 1.080kg/day respectively. The average wastes needed for the design became 0.780 kg/day with 2.340 kg total mass of water. The volume and density of waste slurry gave 2.3070×10^-3m³/day and 1.0143×10³kg/m³ respectively. The volume, diameter, height and thickness of the biodigester gave 0.0865m³, 0.4345m, 0.550m and 0.0028m respectively, while the volume of fermentation chamber was 0.0595m³. Factors (such as forces, power, torque, stress, linear and angular velocities) associated with the design calculations were considered. Pressure analysis was carried out in order to determine the expected pressure of gas in the system. The slurry pressure, slurry height, total pressure and biogas pressure gave 3992.8496N/m², 0.4013m, 4.4697×10⁶N/m², and 4.4657×10⁶N/m² respectively. Equations were derived for the biodigester cover plate and 8 was obtained as the required number of bolts and nuts with corresponding core diameters of 13.546 and 13.835mm respectively. It is hypothesized that the use of metal materials in the design and construction of biogas plants will result in improved efficiency and cost-effectiveness compared to traditional methods.    

KEYWORDS: Mild Steel, Materials Selection, Design, Construction, Biogas Plant, Biodegradable Wastes