An Empirical Testing of a New Biogas Digester Obtained from Engineering Combination of Chinese and Indian Digester Models

This paper proceeds to the analysis, design, construction and operation of a new household biogas digester for rural applications. This new digester is a combination of Chinese and Indian models. Typical biogas digesters generally have low production efficiency which one of its reason is lack of existence of an outlet tank resulting in biogas leakage. In the design and construction of new digester and in order to increase the efficiency, a mechanical mixer is used for feed homogenization and a gas cap is used to collect the biogas from the outlet tank. All calculations are carried out by EES V9.430 in this paper. In the problem analysis, the mixer and the gas cap are investigated in details. To detect the performance improvement, three digesters are constructed and tested empirically including 1) simple, 2) equipped with a mixer, and 3) equipped with mixer and gas cap. In this digester, the feed residence time is selected to be 117 days with total volume of 9,600 liters receiving the food including cow garbage and water mixed with a ratio of 1:1. This new digester has the ability of producing more than one cubic meters of biogas averagely per day. The digester is constructed with reinforced concrete in Firuraq village, Khoy city in the northwestern boundary of country. The outlet tank has a volume of 2 cubic meters and the gas cap has a volume of 350 liters in the optimized state. The initial capacity of the digester is 12 tons of foods and then 80 Kgs of livestock waste daily. Based on the experiments and experimental measurements carried out, the typical and unequipped value of the output gas is 1,014 liters per day which increases 6.5%, 21% and 27.5% using the mixer, gas cap and combination of mixer and gas cap respectively. With respect to the number of the experiment days, the experimental results are presented for 1 to 117 days and the software simulation is carried out during the year.

Anaerobic digester, Design of biogas system, Clean energy, Environmental protection, Biogas.