Theoretical model of gas emission from newly exposed coal walls during uni-directional cutting with sumping at the face center
Abstract：Gas emitted from the coal wall newly exposed during the coal cutting process is a considerable part of the total gas flow from a longwall face. So, accurately predicting the coal wall gas emission is important for determining the method used to dilute the gas concentration. A theoretical model has been developed that describes the time dependence of coal wall gas e- mission during a uni-directional cutting cycle with sumping at the middle of the face. For a giv- en sumping position the coal wall gas emission rate was modeled as a piecewise function of cut- ter position. Based on this piecewise function a curve showing coal wall gas emission vs. time could be drawn. Two expressions were deduced that estimate the peak values of gas emission. Compared to existing results the new model is more reasonable since more details about the coal cutting process are being taken into consideration. Case analyses showed that when the sum- ping position is located at the midpoint of the face the existing expression may over estimate maximum gas emission by 12~ compared to the estimates from this paper.
Keywords：sumping at middle of faceuni-directional cutting sequencecoal wall exposed dur-ing mininggas emissiontheoretical model
Publication Date：2012-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：6( 702-706,724 )