Strength analysis of 157 BQTN-EX materials for biogas reactor tanks

Anaerobic reactor tanks to process wastewater tofu factories to produce biogas fuel as a substitution fuel to cook were constructed. Wastewater from tofu factories is acid with pH of 5–6, therefore reactor was built by acid proof materials and reactor tanks must be coated by UV proof materials. The reactor tanks must resist to mechanical load due to either hydrostatic or gas pressure. The material that fulfill those requirements for reactor tank was 157 BQTN-EX and as the reinforce structure were C-Glass Woven Roving and ceramic fiber. The reactor tank has 250 cm in diameter, 400 cm in height, 60 cm dome height and 0.7 thicknesses. Reactor tanks were reinforced by rings and fins made by the same materials as the reactors tanks. Tensile strength of 157 BQTN-EX was 1,430 kg/cm2 and permissible strength was 170.2 kg/cm2. Reactor tanks contain 20 m3 of wastewater, 3,800 of cut bamboos and 3 m3 of biogas. Analysis of the strength at longitudinal direction was 153.7 kg/cm2, transversal direction was 91.82 kg/cm2 and dome strength was 66.96 kg/cm2. Therefore longitudinal, transversal and dome stress occurred were lower than permissible stress of 157 BQTN-EX materials. Hydrostatic test result at longitudinal was 2×10 −4% and transversal strain were 15×10 −5 %, the both strains are lower than 0.05% therefore the reactor structure will be strong and safe during operation.