Atsushi NAKAZAWA

Development of the digestion gas storage technology in consideration of adsorption heat and impurities in digestion gas

Shoichi FUJITA , Toshiya KOMATSU, and Shuji HIMENO

Effectively using the digestion gas generated from a sewage disposal plant can be contributed to promotion of resources saving and energy saving. However, the delay of storage technology is the hindrance of effective use of digestion gas. And so, we focused attention on adsorption storage. By our research, it was found that the storage capability used this method was 12 to 20 times as much as conventional compressed storage at 0.2 to 0.5 MPa. However, this result, the temperature rise by adsorption heat isn't considered. The purpose in this study is development of the digestion gas storage technology in consideration of the influence of adsorption heat. First, the methane and carbon dioxide adsorption isotherm of various activated carbons were determined, and those were analyzed by Toth equation and temperature dependence Toth equation. Secondly, binary adsorption equilibria of methane and carbon dioxide were measured and analyzed with IAST (Ideal Adsorbed Solution theory). Capacities predicted by IAST were compared with the storage capacity of actual digestion gas. It was shown that IAST is able to calculate about adsorption equilibria of actual digestion gas. Next, adsorption storage of digestion gas in consideration of the influence of adsorption heat was calculated by adiabatic approximation. When digestion gas is stored in activated carbon A, temperature rise on 32 At 0.7 MPa. But storage capability was 10 (0.5MPa) to 16 (0.2MPa) times higher than conventional compressed. The result which compared the temperature rise of a this research and pilot plant, it was in agreement within 3K. Consequently, reliability of prediction was checked.