Ex-situ Model Experiment for Development of Compact Underground Coal Gasification (UCG) System

Akihiro Hamanaka1, Fa-qiang Su 1, Ken-ichi Itakura1, Kohki Satoh1, Kazuhiro Takahashi1, Gota Deguchi2, Jun-ichi

Kodama3 and Koutarou Ohga3

1. Muroran Institute of Technology, Muroran, Japan

2. Underground Resources Innovation Network, Sapporo, Japan

3. Hokkaido University, Sapporo, Japan

Abstract: Underground Coal Gasification (UCG) is a technique to recover coal energy in the form of gas in the surface by burned and gasified in an underground coal seam abandoned for either technical or economic reasons. The product gas consists of several combustible gases: carbon monoxide, hydrogen, methane, and other hydrocarbon gases. Recently, this technology is focused as a clean coal technology to recover unused coal resources without environmental impacts. However, it might be difficult to adopt conventional UCG systems in Japan because of geological conditions that are complicated by the existence of faults and folds. Therefore, an alternative UCG system, compact, safe, and highly efficient have to be introduced. In this study, UCG model experiments were conducted for two UCG system, linking method (a conventional UCG system) and co-axial method (an alternative UCG system), by using artificial coal seam whose size was 0.550.602.74 m made by crushed coal. Three types of model experiments, test 1 (linking method), test 2 (linking method), and test 3 (co-axial method), were carried out. In test 1 and test 2, the average calorific value of product gas was 6.79 MJ/Nm3 and 8.25 MJ/Nm3, respectively, whereas in test 3, the value was 4.85 MJ/Nm3. Additionally, gasification zone of co-axial method is smaller than that of linking method. These results demonstrate that co-axial UCG system needs more consideration to improve the quality of product gas and gasification zone.

Key words: underground coal gasification, gasification, unused coal, co-axial UCG system