Adiabatic spontaneous coal combustion period derived from the thermal effect of spontaneous combustion

Energy ◽  
2021 ◽  
pp. 122101
Author(s):  
Li Yan ◽  
Hu Wen ◽  
Wenyong Liu ◽  
Yongfei Jin ◽  
Yin Liu ◽  
...  
Keyword(s):  
Thermal Effect ◽  
Coal Combustion ◽  
Spontaneous Combustion ◽  
Spontaneous Coal Combustion

scholarly journals The Impact of the Strength of Roof Rocks on the Extent of the Zone with a High Risk of Spontaneous Coal Combustion for Fully Powered Longwalls Ventilated with the Y-Type System—A Case Study

2019 ◽  
Vol 9 (24) ◽  
pp. 5315 ◽  
Author(s):  
Magdalena Tutak ◽  
Jarosław Brodny
Keyword(s):  
Tensile Strength ◽  
High Risk ◽  
Coal Combustion ◽  
Spontaneous Combustion ◽  
Type System ◽  
Hard Coal ◽  
Risk Zone ◽  
Air Stream ◽  
Spontaneous Coal Combustion ◽  
Roof Rocks

During the ventilation of longwalls in hard coal mines, part of the air stream migrates to the goaves with caving. These goaves constitute a space (void) filled with rocks following coal extraction. In the case where these goaves contain coal susceptible to spontaneous combustion, the flow of such an air stream through the goaves may lead to the formation of favourable conditions for coal oxidation, self-heating and spontaneous combustion. Such an area is referred to as the zone with a particularly high risk of spontaneous coal combustion (endogenous fires). The location and extent of this zone depend on many factors, with one of the most important being the permeability of the goaves which determines the tensile strength of the roof rocks forming the caving. This strength determines the propensity of these rocks to transform into the state of caving and the degree of tightness of the cave-in rubble (treated as a porous medium). The purpose of the present paper is to determine how the tensile strength of roof rocks influences the extent of the zone with a particularly high risk of spontaneous coal combustion (endogenous fires) in caving goaves of the longwalls ventilated with the Y-type system. To achieve this goal, model-based tests were conducted for a region of the longwall mined with caving and ventilated with the Y-type system. Critical air speed and oxygen concentration values in the caving goaves of this longwall were determined for the actual conditions of exploitation. These parameters define the risk zone of spontaneous coal combustion. The tests also helped to determine the extent of this zone, depending on the strength of the rocks forming the caving. The results obtained unequivocally indicate that the type of rocks forming the caving affects its permeability and the extent of the risk zone for spontaneous coal combustion. At the same time, the distribution of this zone is substantially different than in the case of other ventilation systems. The results obtained are of real practical significance for preventive measures to reduce fire risks. The effectiveness of these measures significantly improves the safety of mining exploitation.

scholarly journals Distribution law for the danger area for spontaneous coal combustion in a dynamic goaf with low air leakage speed

2020 ◽  
pp. 308-308
Author(s):  
Qiuling Zuo ◽  
Jingshan Li ◽  
Yujie Wang
Keyword(s):  
Coal Combustion ◽  
Spontaneous Combustion ◽  
Oxidation Zone ◽  
Distribution Area ◽  
Air Leakage ◽  
Exponential Relationship ◽  
Working Face ◽  
Spontaneous Coal Combustion ◽  
Mining Face ◽  
The Relationship

This paper examines the relationship between the advancement of the working face and the distribution of spontaneous coal combustion under a low air leakage wind speed in a goaf. Based on the unsteady state simulation method, the process of spontaneous coal combustion was simulated in a fully mechanized coal mining face at different advancing speeds. The relationship between different advancing speeds and the distribution area of the oxidation zone of spontaneous coal combustion in a goaf was clarified. A safe advancing speed was determined. Furthermore, the advancement of the working face altered the area of spontaneous high temperature inside the goaf. An increase in the advancing speed increased the length of time of spontaneous combustion in the leftover coal. An exponential relationship was demonstrated between the spontaneous combustion area and the advancement of the fully mechanized mining face. When the oxygen concentration was used as a calculation indicator, the width of the oxidation zone was asymmetrical on the inlet and outlet, and the advancing distance of the working surface increased when the distance was shorter than 90 m and the return side was smaller than the inlet side. When the advancing distance was longer than 90 m, the width of the spontaneous combustion oxidation zone distribution remained unchanged. The study clarified the relationship between the distribution of the danger area for spontaneous coal combustion and advancing speed. This could provide a theoretical basis for the prevention and control technology of the spontaneous combustion of broken coal in a dynamic goaf.

A model for assessing the compound risk represented by spontaneous coal combustion and methane emission in a gob

2020 ◽  
Vol 273 ◽  
pp. 122925 ◽  
Author(s):  
Yu Xu ◽  
Zijun Li ◽  
Huasen Liu ◽  
Xiaowei Zhai ◽  
Rongrong Li ◽  
...  
Keyword(s):  
Methane Emission ◽  
Coal Combustion ◽  
Spontaneous Coal Combustion

Numerical evaluation of inclined heat pipes on suppressing spontaneous coal combustion

2020 ◽  
Vol 56 (6) ◽  
pp. 1861-1874 ◽  
Author(s):  
Fangming Cheng ◽  
Zhuchuan Chang ◽  
Jun Deng ◽  
Fan Nan ◽  
Anbang Zhang ◽  
...  
Keyword(s):  
Coal Combustion ◽  
Numerical Evaluation ◽  
Heat Pipes ◽  
Spontaneous Coal Combustion

Relationship Between the Nanopore Structure and Basic Characteristics of Coal with the Protogenetic CO Content

2021 ◽  
Vol 21 (1) ◽  
pp. 505-514
Author(s):  
Bo Tan ◽  
Gang Cheng ◽  
Xianbing Yang ◽  
Xiaoman Zhu ◽  
Mingming Hu ◽  
...  
Keyword(s):  
Coal Combustion ◽  
Coal Sample ◽  
Synthesis Process ◽  
Elemental Content ◽  
Coal Seams ◽  
Gas Emission ◽  
Internal Factors ◽  
Exponential Power Distribution ◽  
Spontaneous Coal Combustion ◽  
Co Gas

In the prediction and forecasting of spontaneous coal combustion, protogenetic CO produced in the process of coal oxidation is used as the indicator gas, but the sources of CO gas in coal seams are extensive. Protogenetic CO in coal seams often interferes with predictions of spontaneous coal combustion. To predict the content of protogenetic CO gas in coal seams and its emission, this study established an experimental system of protogenetic CO content and emission in coal seams. Six groups of coal samples were tested, and the CO emission content was determined per hour within 24 hours of obtaining each coal sample. Four kinds of protogenetic CO gas emission indexes were defined. Then, internal factors of coal, including industrial components, elemental content and pore structure, were analysed. Finally, the relationship between the protogenetic CO gas emission index of coal seams and the internal factors of coal was obtained. The results indicate that the relation between the CO dispersion concentration and the time of the coal sample follows an exponential power distribution. The internal factors of coal influence the content and emission of protogenetic CO in coal seams, but there is no strict correlation with each parameter as it is a multi-parameter correlation synthesis process.

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