Evaluation of gasification zone and energy recovery during underground coal gasification (UCG) experiments
Underground Coal Gasification (UCG) is a promising environmentally acceptable clean-coal technology.UCG creates a combustion reactor in an underground coal seam to collect heat energy and gases (hydrogen, methane, etc.) through the same chemical reactions that occur in surface gasifiers.However, associated environmental issues, improperly executed operations, and designed gasification processes can restrict the applicability of UCG.Precise control of the combustion reactor and evaluation of energy recovery are difficult because the techniques to evaluate and control the fracturing activity, and gasification condition in the underground coal seam around the combustion area remain undeveloped.During UCG operations, evaluation of the coal combustion cavity growth and precise control of the reactor are important to ensure effective combustion and efficient gasification.To investigate the distribution and extent of fracture activity, and to evaluate the propagation of the combustion area in the UCG model experiments and small-scale field tests, we used acoustic emissions (AE) monitoring and temperature measurements.The AE source locations and moment tensor analysis were investigated to establish a crack distribution model.Results also showed that many AE events occurred during coal combustion.The AE activity was related closely to the temperature change occurring inside the coal.This AE generation apparently results from crack initiation and extension around the coal combustion area, which occur because of thermal stress.Moreover, coal consumption was investigated by estimating the reaction process of coal gasification based on theproposed stoichiometric method using product gas compositions.Results from the estimated values of coal consumption support experimental observations for the rational error range and provide a better evaluation of UCG effects.Results show that the local temperature change strongly affects AE activities when fracture occurs inside the coal, and the AE monitoring is a useful tool to evaluate combustion reactors for efficient and safe UCG systems.It also provides necessary data and parameters for UCG simulation development.Moreover, this stoichiometric approach is simple and useful for evaluating the energy recovery during UCG.
Underground Coal Gasification UCG Models Combustion Cavity Acoustic Emission Energy Recovery
Faqiang.Su K.Itakura G.Deguchi K.Ohga J.Kodama
Muroran Institute of Technology, Muroran, Japan Underground Resources Innovation Network, NPO Sapporo, Japan Hokkaido University, Sapporo, Japan
国际会议
The 34th International Conference on Ground Control in Mining (ICGCM) 2015(34届国际采矿岩层控制会议)
焦作
英文
55-61
2015-10-17（万方平台首次上网日期，不代表论文的发表时间）