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Lu Y.-L.,China University of Mining and Technology | Wang L.-G.,China University of Mining and Technology | Tang F.-R.,China University of Mining and Technology | He Y.,ENN Coal Gasification Mining Co.
Meitan Xuebao/Journal of the China Coal Society | Year: 2012

The thermo-physical properties and uniaxial compression experiments of mudstone and sandstone under high temperature were conducted to obtain the basic physical and mechanical parameters at varying temperatures. The governing equations of thermal-mechanical coupling incorporating the evolution of rock damage were established based on the thermodynamics and elastic mechanics. With the background of an underground coal gasification field, the combustion cavity growth under the thermal-mechanical interaction was modeled and the characteristics of temperature and fracture distribution of overlying strata were analyzed. Finally, the bore hole survey method was employed to test the height of fractured zones of overlying strata. The field test results agree with the numerical simulation results, which verify the rationality of the numerical model.

Yang L.H.,State Key Laboratory of Coal Based Low Carbon Energy | Yang L.H.,ENN Coal Gasification Mining Co. | Pang X.L.,State Key Laboratory of Coal Based Low Carbon Energy | Liu S.Q.,China University of Mining and Technology | Chen F.,State Key Laboratory of Coal Based Low Carbon Energy
Energy Sources, Part A: Recovery, Utilization and Environmental Effects | Year: 2010

In this article, through model testing of the temperature-control blasting underground coal gasification, change features of temperature and gas pressure in the gasifier are studied. Measurement results show that in the process of the gasification of coal seams, with the passage of time, the dislodging effect of the coal seams from the thermal explosion gradually improves, the rate of the temperature rise quickens, and the temperature gradient of the coal seams media continuously lowers. According to measurement data, the average dropping rate of temperature gradient in the direction of slope for seams is 0.156°C/cm.h, and in the direction of thickness, 0.201°C/cm.h. Characteristics of zones in the gasification space are also pointed out. The experimental data indicate that, in a drop out zone, the change of fluid pressure is small; in a combustion zone, the gas pressure decreases sharply, with the pressure difference of 210-290 Pa; in the area dislodged by explosions, the gas pressure is relatively small, generally between 20 and 70 Pa. Copyright © 2010 Taylor & Francis Group, LLC.

Hongtao L.,ENN Group | Feng C.,ENN Group | Feng C.,ENN Coal Gasification Mining Co. | Xia P.,ENN Group | And 2 more authors.
Mining Science and Technology | Year: 2011

Two-stage underground coal gasification was studied to improve the caloric value of the syngas and to extend gas production times. A model test using the oxygen-enriched two-stage coal gasification method was carried out. The composition of the gas produced, the time ratio of the two stages, and the role of the temperature field were analysed. The results show that oxygen-enriched two-stage gasification shortens the time of the first stage and prolongs the time of the second stage. Feed oxygen concentrations of 30%, 35%, 40%, 45%, 60%, or 80% gave time ratios (first stage to second stage) of 1:0.12, 1:0.21, 1:0.51, 1:0.64, 1:0.90, and 1:4.0 respectively. Cooling rates of the temperature field after steam injection decreased with time from about 19.1-27.4 °C/min to 2.3-6.8 °C/min. But this rate increased with increasing oxygen concentrations in the first stage. The caloric value of the syngas improves with increased oxygen concentration in the first stage. Injection of 80% oxygen-enriched air gave gas with the highest caloric value and also gave the longest production time. The caloric value of the gas obtained from the oxygen-enriched two-stage gasification method lies in the range from 5.31 MJ/Nm3 to 10.54 MJ/Nm3. © 2011, China University of Mining & Technology. All rights reserved.

A gas injection apparatus with a controllable gas injection point, a gas injection process, and a gasification method. The gas injection apparatus comprises a directional well channel, where a continuous oil pipe is provided in the directional well channel. The continuous oil pipe is connected to an oxygen/oxygen-rich gas pipeline. An annular gap between the continuous oil pipe and the directional well channel is connected to an auxiliary gasification agent pipeline and a vapor pipeline. A gas injection wellhead is provided at the start end of the continuous oil pipe, and a nozzle is provided at the tail end. In the present invention, based on directional drilling and continuous oil pipe technologies, the movement of a gas injection point is implemented by using a manner of combining directional drilling and a continuous oil pipe; meanwhile, by using a principle of controlling reverse combustion by adjusting a gasification agent injection parameter, the movement of a working surface position and a combustion speed of a flame are regulated, so as to achieve the objective of ignition and gasification for reverse combustion of an underground coal layer.

Enn Coal Gasification Mining Co. | Date: 2013-09-18

Provided is a method for joint-mining of coalbed gas and coal. The method comprises: a well-drilling step; a fracturing and penetration step; a coalbed gas extraction step: an ignition step, and an underground gasification step. The method combines an underground coal gasification technology and a coalbed gas extraction technology, not only allows for utilization of the high temperature of underground gasification to heat a coalbed. thus increasing the permeability of a coal seam. and increasing the recovery rate of the coalbed gas, but also allows for utilization of the coalbed gas to perform the drilling and the fracturing and penetration processes, thus increasing the efficiency of underground coal gasification for mining.

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