Investigation of Underground Coal Gasification in Laboratory Conditions: A Review of Recent Research

Abstract

The underground coal gasification (UCG) technology converts coal into product gas and provides the option of environmentally and economically attractive coal mining. Obtained syngas can be used for heating, electricity, or chemical production. Numerous laboratory coal gasification trials have been performed in the academic and industrial fields. Lab-scale tests can provide insight into the processes involved with UCG. Many tests with UCG have been performed on ex situ reactors, where different UCG techniques, the effect of gasification agents, their flow rates, pressures, and various control mechanisms to improve gasification efficiency and syngas production have been investigated. This paper provides an overview of recent research on UCG performed on a lab scale. The study focuses on UCG control variables and their optimization, the effect of gasification agents and operating pressure, and it discusses results from the gasification of various lignites and hard coals, the possibilities of steam gasification, hydrogen, and methane-oriented coal gasification, approaches in temperature modeling, changes in coal properties during gasification, and environmental risks of UCG. The review focuses on laboratory tests of UCG on ex situ reactors, results, and the possibility of knowledge transfer to in situ operation.

Critical review of methods for intensifying the gas generation process in the reaction channel during underground coal gasification (UCG)

“…Reversing the direction of gas flows reflects a periodic change in the supply and withdrawal directions. This interaction of flows makes it possible to transform the oxidation zone into a reduction zone and vice versa [123]- [127]. When, due to the thermal effects of endothermic reactions (2)-( 4), the temperature in the reduction zone is reduced to 600-800°С, the gas-blast flow is reversed.…”

Use of Lignite Processing Products as Additives to Road Petroleum Bitumen

“…As commonly known, in addition to being combusted in thermal power plants, lignite (brown coal) is part of the raw material base of many technological processes, particularly gasification and oxidative desulfurization, and it is also used as a raw material for obtaining components of boiler fuel or bitumen [1][2][3][4]. For example, the authors of [5] provide complex study results on using lignite from the Oleksandriysk deposit of Ukraine for combined gasification with the coal tar of coke chemical origin and walnut shell.…”

Managing the process of underground coal gasification

“…Underground coal gasification is an advantage and addition to traditional coal mining technologies. It is a key technology for implementing lowcarbon programs for mining and processing coal reserves [15]. In recent years, underground coal gasification has been developing at a very fast pace and has shown great po tential.…”