Abstract
Underground coal gasification (UCG) is a technique to recover coal energy without mining by converting coal into a valuable gas. Model UCG experiments on a laboratory scale were carried out under a low flow rate (6~12 L/min) and a high flow rate (15~30 L/min) with a constant oxygen concentration. During the experiments, the coal temperature was higher and the fracturing events were more active under the high flow rate. Additionally, the gasification efficiency, which means the conversion efficiency of the gasified coal to the product gas, was 71.22% in the low flow rate and 82.42% in the high flow rate. These results suggest that the energy recovery rate with the UCG process can be improved by the increase of the reaction temperature and the promotion of the gasification area.
Highlights
Underground coal gasification (UCG) is a technique to extract energy from coal in the form of heat energy and combustible gases through chemical reactions in the underground gasifier
In the UCG process, the oxidants are injected from an injection well in order to promote the gasification promote product gas2,consists ofhydrocarbons
Difficult to control the quality of the of the product gas during the UCG process because the conditions of the underground reactor are product gas during the UCG process because the conditions of the underground reactor are constantly constantly changing due to changes in the temperature field and the expansion of the cavity [7,8]
Summary
Underground coal gasification (UCG) is a technique to extract energy from coal in the form of heat energy and combustible gases through chemical reactions in the underground gasifier. The annual consumption of coal in Japan was 177 million tons in 2014 while the annual domestic coal production is only. Japan has an underground and several surface coal mines in a limited region. In the UCG process, the oxidants are injected from an injection well in order to promote the gasification promote product gas2 ,consists ofhydrocarbons. 2, and other reactions, the and gasification product gas reactions, consists of and CO, H and other recovered from. Reaction duringroughly the UCG process a production well. Promote the gasification oxidation process, reaction meaning the oxidation reaction makes theReduction temperature of the coal seam rise. These chemical reactions are promoted under reactions are promoted under high temperatures.
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