Effect Analysis of Nitrogen Injection on the Variation of “Oxidation Zone” in Coal Mine Gob Based on Numerical Simulation

2016 ◽  
Vol 9 (1) ◽  
pp. 47-54
Author(s):  
Jing Shen ◽  
Mingran Chang
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Heat Dissipation ◽  
Spontaneous Combustion ◽  
Oxidation Zone ◽  
Effect Analysis ◽  
Mine Fire ◽  
Nitrogen Injection ◽  
The Difference ◽  
Residual Coal

One of the main reasons for coal mine fire is spontaneous combustion of residual coal in gob. As the difference of compaction degree of coal and rock, the underground gob can be considered as a porous medium and divided into “three zones” in accordance with the criteria. The “three zones” are “heat dissipation zone”, “oxidation zone” and “choking zone”, respectively. Temperature programming experiments are taken and numerical simulation with obtained experimental data is utilized to analyze the distribution of “three zones” in this paper. Different width and depth of “oxidation zone” are obtained when the inlet air velocity is changed. As the nitrogen injection has inhibition effect on spontaneous combustion of residual coal in gob, nitrogen is injected into the gob. The widths of “oxidation zone” are compared before and after nitrogen injection. And ultimately the optimum location and volume of nitrogen injection are found out.

scholarly journals Distribution of spontaneous combustion three zones and optimization of nitrogen injection location in the goaf of a fully mechanized top coal caving face

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0256911
Author(s):  
Yun Qi ◽  
Wei Wang ◽  
Qingjie Qi ◽  
Zhangxuan Ning ◽  
Youli Yao
Keyword(s):  
Combustion Zone ◽  
Heat Dissipation ◽  
Spontaneous Combustion ◽  
Simulation Analysis ◽  
Distribution Area ◽  
Nitrogen Injection ◽  
Residual Coal ◽  
Controlling Measures ◽  
And Control ◽  
The Impact

In order to effectively prevent and control spontaneous combustion of residual coal in the goaf and reduce the waste of nitrogen caused by setting the position of nitrogen injection, 1303 fully mechanized coal caving faces of the Jinniu Mine are studied. By deploying a bundle tube monitoring system in the inlet air side and return air side of the goaf, changes in gas concentration in the goaf are continuously monitored. In addition, the distribution area for spontaneous combustion three-zone in the goaf is divided into heat dissipation zone, oxidized spontaneous combustion zone, and suffocation zone. Simulations from the COMSOL Multiphysics 5.3 software provide insight based on the three zones division standard of spontaneous combustion in the goaf. The gradual deepening of the nitrogen injection position into the goaf affects the lower limit of the oxidized spontaneous combustion zone significantly, but the impact on the upper limit of the oxidized spontaneous combustion zone is not obvious and is negligible. With regard to the width of the oxidized spontaneous combustion zone, it initially decreases followed by a gradual increase. Numerical calculations suggest the optimal nitrogen injection position is 40 m from the roof cutting line, with an oxidized spontaneous combustion zone width of 28 m. Based on the simulation analysis results, nitrogen injection controlling measures have been adopted for spontaneous combustion of residual coal in the goaf of the 1303 fully mechanized coal caving faces, and coal self-ignition in the goaf has been successfully extinguished.

Study on the Residual Coal Distribution and the Improving Measures

2014 ◽  
Vol 556-562 ◽  
pp. 822-825
Author(s):  
He Bing Luan
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Production System ◽  
Recovery Rate ◽  
Distribution Characteristics ◽  
The Core ◽  
Residual Coal ◽  
Core Problem

The core problem of fully mechanized top-coal caving technology is to accurately grasp residual coal distribution characteristics and improve the recovery rate to the highest possible. Based on the top-caving working site in some coal mine, combined with the numerical simulation on the residual coal in end roadway, the distribution of residual coal is analyzed. Corresponding improvements on the production system have been proved to be efficient for recovering the residual coal.

Dynamic numerical simulation of coal mine fire for escape capsule installation

2012 ◽  
Vol 50 (4) ◽  
pp. 600-606 ◽  
Author(s):  
Shengzhu Zhang ◽  
Zongzhi Wu ◽  
Rui Zhang ◽  
Jianning Kang
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Mine Fire ◽  
Dynamic Numerical Simulation ◽  
Coal Mine Fire

scholarly journals Risk Identification of Coal Spontaneous Fire Based on COWA Modified G1 Combination Weighting Cloud Model

2021 ◽  
Author(s):  
Guorui Su ◽  
Baoshan Jia ◽  
Peng Wang ◽  
Ru Zhang ◽  
Zhuo Shen
Keyword(s):  
Coal Mine ◽  
Heat Dissipation ◽  
Spontaneous Combustion ◽  
Cloud Model ◽  
Influence Factors ◽  
Fire Risk ◽  
Risk Identification ◽  
Weighted Averaging ◽  
Risk Level ◽  
Spontaneous Fire

Abstract To realize the scientific judgment of spontaneous fire risk in the coal mine, the spontaneous fire influence factors were analyzed from the three aspects of coal spontaneous combustion tendency, air leakage, and oxygen supply, heat storage and heat dissipation. And the basis for the evaluation of t spontaneous fire grade was constructed. Combination ordered weighted averaging (COWA) calculation was introduced to optimizes G1 subjective weighting, and a COWA modified G1 combined weighting cloud model was proposed to identify the spontaneous fire risk in the coal mine. Finally, the rationality of the model was verified with actual cases. The research results show that the spontaneous fire risk level in the Lingquan coal mine is relatively safe, which is consistent with the actual situation. And the spontaneous combustion tendency of coal is the leading factor affecting spontaneous fire risk.

scholarly journals Study on the Convective Heat Transfer and Fluid Flow of Mini-Channel with High Aspect Ratio of Neutron Production Target

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4020
Author(s):  
Peng Sun ◽  
Yiping Lu ◽  
Jianfei Tong ◽  
Youlian Lu ◽  
Tianjiao Liang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Aspect Ratio ◽  
Optimization Design ◽  
Heat Dissipation ◽  
Neutron Production ◽  
Thermal Design ◽  
Maximum Deviation ◽  
Test Channel ◽  
Production Target

In order to provide a theoretical basis for the thermal design of the neutron production target, flow and heat transfer characteristics are studied by using numerical simulations and experiments. A rectangular mini-channel experimental model consistent with the geometric shape of the heat dissipation structure of neutron production target was established, in which the aspect ratio and gap thickness of the test channel were 53.8:1 and 1.3 mm, respectively. The experimental results indicate that the critical Re of the mini-channel is between 3500 and 4000, and when Re reaches 21,000, Nu can reach 160. The simulation results are in good agreement with the experimental data, and the numerical simulation method can be used for the variable structure optimization design of the target in the later stage. The relationship between the flow pressure drop of the target mini-channel and the aspect ratio and Re is obtained by numerical simulation. The maximum deviation between the correlation and the experimental value is 6%.

Numerical Simulation of Filling and Solidification in Sand Casting by Procast

2013 ◽  
Vol 791-793 ◽  
pp. 550-553 ◽  
Author(s):  
Dong Dong Han ◽  
Cheng Jun Wang ◽  
Juan Chang ◽  
Lei Chen ◽  
Huai Bei Xie
Keyword(s):  
Numerical Simulation ◽  
Heat Dissipation ◽  
Solidification Process ◽  
Simulation Software ◽  
Sand Casting ◽  
Production Costs ◽  
Raw Material ◽  
Casting Defects ◽  
Three Dimension ◽  
Filling And Solidification

At present, pulley produced in China has been able to meet the demand of domestic and international markets. But there are many problem of the pulley industry in our country, such as too many production enterprises and the low level of export products. And as components of drive system are light weight and raw material price of pulley casting are rising, manufacturing requirements of the pulley are also more and more high. Aiming at the casting defects of pulley that enterprise current product, pulley casting blank model of common material HT250 be made by three-dimension software, numerical simulation of filling and solidification process for pulley sand casting by the casting simulation software Procast, the size and location of the various casting defects were forecasted and analyzed, reflecting the pulley filling and solidification process of the actual situation, due to the thicker pulley rim and less heat dissipation, position of shrinkage is close to the middle of rim [, a method of eliminating defects is proposed to realize sequential solidification, and thus to minimize porosity shrinkage and improve casting performance and reduce casting time and reduce production costs.

scholarly journals Morwell Coal Mine Fire as a Cascading Disaster: A Case Study

2019 ◽  
Vol 34 (s1) ◽  
pp. s8-s8 ◽  
Author(s):  
Dudley McArdle ◽  
Caroline Spencer ◽  
Frank Archer
Keyword(s):  
Coal Mine ◽  
Core Structure ◽  
Disaster Mitigation ◽  
Alternative View ◽  
Human Society ◽  
Adequate Model ◽  
Mine Fire ◽  
Sequence Of Events ◽  
Coal Mine Fire

Introduction:Despite the influential Hyogo and Sendai Frameworks, risk remains poorly understood in the emergency preparedness sector. Hazard assessment and risk management are usually considered before events. An alternative view considers risk as a cascade of potential consequences throughout an event. The 2014 fire in the Victorian rural community of Morwell included a three-phased event: a small bush fire, from which embers ignited a persistent fire in a disused open cut brown coal mine fire. The consequent air pollution precipitated a public health emergency in the nearby community of 15,000 people.Aim:To examine this event as a case study to investigate concordance with accepted definitions and key elements of a cascading event.Methods:Selected literature informed a risk cascade definition and model as a framework to examine the key post-event public inquiries available in the public domain.Results:Informed by a Conceptual Framework for a Hazard Evolving into a Disaster (Birnbaum et al., 2015), Wong and colleagues promote a Core Structure of a Comprehensive Framework for Disaster Evaluation Typologies (Wong, 2017). This Core Structure provided an adequate model to examine the sequence of events in the Morwell event. Definitions of cascading effects is more complex (Zuccaro et al., 2018). Our analysis of the Morwell event used the authoritative definition of cascading disasters published by Pescaroli and Alexander (2015). Using this definition, the Morwell event increased in progression over time and generated unexpected secondary events of strong impact. The secondary events could be distinguished from the original source of disaster, and demonstrated failures of physical structures as well as inadequacy of disaster mitigation strategies, while highlighting unresolved vulnerabilities in human society.Discussion:The Morwell coal mine fire of 2014 reflects the key criteria of a cascading disaster and provides understandings to mitigate the consequences of similar events in the future.

Reasonable Entry Layout of Lower Seam in Multi-Seam Mining Based on Numerical Simulation

2013 ◽  
Vol 295-298 ◽  
pp. 2980-2984
Author(s):  
Xiang Qian Wang ◽  
Da Fa Yin ◽  
Zhao Ning Gao ◽  
Qi Feng Zhao
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Coal Seam ◽  
Coal Mine ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Geological Conditions ◽  
Seam Mining

Based on the geological conditions of 6# coal seam and 8# coal seam in Xieqiao Coal Mine, to determine reasonable entry layout of lower seam in multi-seam mining, alternate internal entry layout, alternate exterior entry layout and overlapping entry layout were put forward and simulated by FLAC3D. Then stress distribution and displacement characteristics of surrounding rock were analyzed in the three ways of entry layout, leading to the conclusion that alternate internal entry layout is a better choice for multi-seam mining, for which makes the entry located in stress reduce zone and reduces the influence of abutment pressure of upper coal seam mining to a certain extent,. And the mining practice of Xieqiao Coal Mine tested the results, which will offer a beneficial reference for entry layout with similar geological conditions in multi-seam mining.

Sign in / Sign up

Export Citation Format

Share Document