scholarly journals Study on Foamed Concrete Used as Gas Isolation Material in the Coal Mine Goaf

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4377
Author(s):  
Changyu Xu ◽  
Lijun Han ◽  
Maolin Tian ◽  
Yajie Wang ◽  
Yuhao Jin
Keyword(s):  
Coal Mine ◽  
Gas Permeability ◽  
Orthogonal Experiment ◽  
Dry Density ◽  
Gas Concentration ◽  
Convection Diffusion ◽  
Engineering Requirement ◽  
Foamed Concrete ◽  
New Type ◽  
Sealing Materials

In view of the serious threat of gas accumulation in the coal mine goaf and the limitations of the existing gas sealing materials, the orthogonal experiment was developed to study a new type of foamed concrete for mine gas sealing. Dry density, gas permeability, and compressive strength were studied as the material indicators according to the demands of the gas isolation material in the coal mine goaf, and the experimental results showed that foam content was the most important factor. Meanwhile, the optimum mix was selected according to the influence of foam content as well as the engineering requirement. Then two application modes of this foamed concrete for goaf gas isolation were put forward, after which the convection-diffusion model of gas was built by COMSOL Multiphysics (COMSOL Inc., Stockholm, Sweden) to reveal the mechanism of different application modes using the parameters of the new foamed concrete. Simulation results showed that this foamed concrete used as isolating material for goaf gas could significantly decrease the gas concentration in workface, which can provide a reference for similar engineering.

Mix Ratio Design and Performance Optimization of Vitrified Microsphere Insulating Mortar

2012 ◽  
Vol 476-478 ◽  
pp. 1639-1642
Author(s):  
Jin Ping Chen
Keyword(s):  
Performance Optimization ◽  
Raw Materials ◽  
Orthogonal Experiment ◽  
Polypropylene Fiber ◽  
Physical And Mechanical Properties ◽  
Dry Density ◽  
Building Insulation ◽  
Composition Materials ◽  
New Type ◽  
And Performance

Vitrified microsphere insulation mortar is a new type building insulation mortar which developed in recent years, with having the advantages of well workability, high intensity and fire prevention. But because the vitrified microsphere we use of which much exists on the defects of high dry density and bad insulation effect, it analyzed deeply kinds of factors which influence on the physical and mechanical properties of vitrified microsphere insulation mortar, making use of orthogonal experiment to optimize the composition materials of insulation mortar. The orthogonal test results show that the most influential raw materials factors to mortar insulation properties and 28d compressive strength followed by aggregate, polypropylene fiber, fly ash and latex powder.

scholarly journals The performance of ultra-lightweight foamed concrete incorporating nanosilica

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Mohamed Abd Elrahman ◽  
Pawel Sikora ◽  
Sang-Yeop Chung ◽  
Dietmar Stephan
Keyword(s):  
Wall Thickness ◽  
Probabilistic Approach ◽  
Drying Shrinkage ◽  
Dry Density ◽  
Optimal Dosage ◽  
X Ray ◽  
Mechanical And Physical Properties ◽  
Fresh State ◽  
Foamed Concrete ◽  
The Stability

AbstractThis paper aims to investigate the feasibility of the incorporation of nanosilica (NS) in ultra-lightweight foamed concrete (ULFC), with an oven-dry density of 350 kg/m3, in regard to its fresh and hardened characteristics. The performance of various dosages of NS, up to 10 wt.-%, were examined. In addition, fly ash and silica fume were used as cement replacing materials, to compare their influence on the properties of foamed concrete. Mechanical and physical properties, drying shrinkage and the sorption of concrete were measured. Scanning electron microscopy (SEM) and X-ray microcomputed tomography (µ-CT) and a probabilistic approach were implemented to evaluate the microstructural changes associated with the incorporation of different additives, such as wall thickness and pore anisotropy of produced ULFCs. The experimental results confirmed that the use of NS in optimal dosage is an effective way to improve the stability of foam bubbles in the fresh state. Incorporation of NS decrease the pore anisotropy and allows to produce a foamed concrete with increased wall thickness. As a result more robust and homogenous microstructure is produced which translate to improved mechanical and transport related properties. It was found that replacement of cement with 5 wt.-% and 10 wt.-% NS increase the compressive strength of ULFC by 20% and 25%, respectively, when compared to control concrete. The drying shrinkage of the NS-incorporated mixes was higher than in the control mix at early ages, while decreasing at 28 d. In overall, it was found that NS is more effective than other conventional fine materials in improving the stability of fresh mixture as well as enhancing the strength of foamed concrete and reducing its porosity and sorption.

Study on Coal Mine Gas Monitoring System Based on Arduino

2014 ◽  
Vol 1073-1076 ◽  
pp. 2173-2176 ◽  
Author(s):  
Hui Chun Gao ◽  
Chao Jun Fan ◽  
Jun Wen Li ◽  
Ming Kun Luo
Keyword(s):  
Monitoring System ◽  
Coal Mine ◽  
Low Cost ◽  
Gas Monitoring ◽  
Underground Coal Mine ◽  
Gas Concentration ◽  
Coal Mine Gas ◽  
Good Market ◽  
Mine Gas ◽  
Sd Card

Aimed at the frequency gas accident of coal mine, we designed a coal mine gas monitoring system based on Arduino microcontroller. The MQ-4 gas sensor was used to collect gas concentration, wireless ZigBee was used to transfer data of gas concentration to PC. The system can display gas concentration real-timely by LCD and use SD card to store the data. The system will send out sound and light alarm when the gas concentration overruns. Industrial tests have been carried out in Wuyang coal mine. Results show that gas monitoring system can well adapt to environment of underground coal mine and the measurement is accurate. The system is real-time monitoring and early warning. It has the characteristics of low power consumption, low cost, wireless, good market prospect.

Hardware Design of Coal Mine Safety Monitoring System Based on WSN

2012 ◽  
Vol 546-547 ◽  
pp. 1483-1488
Author(s):  
Shu Ren Han ◽  
Jun Wang ◽  
Ling Liang ◽  
Xian Peng Liu
Keyword(s):  
Monitoring System ◽  
Coal Mine ◽  
Hardware Design ◽  
Mine Safety ◽  
Sink Node ◽  
Function Structure ◽  
Gas Concentration ◽  
Coal Mine Safety ◽  
Safety Monitoring System ◽  
Safety Production

In the safety production of coal mine, monitoring exact and real-time mine parameter is very important and key problem. The monitoring system of mine environment with wireless is designed, which is based on the structure of wireless sensor network (WSN).The system includes sensor node, Sink node and monitoring center. In the paper, the function structure and hardware design of sensor are introduced for the monitoring of temperature, humidity and gas concentration, and the function structure and hardware design of sink node is designed. The system has low power, rapid real-timing, stable running. Etc. This can satisfy with the requirement of WSN and suit the monitoring of bad environments. It will have wide application prospect.

scholarly journals Anomaly Detection for Time Series with Difference Rate Sample Entropy and Generative Adversarial Networks

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Keke Gao ◽  
Wenbin Feng ◽  
Xia Zhao ◽  
Chongchong Yu ◽  
Weijun Su ◽  
...  
Keyword(s):  
Time Series ◽  
Anomaly Detection ◽  
Normal Mode ◽  
Coal Mine ◽  
Spontaneous Combustion ◽  
Sample Entropy ◽  
Generative Adversarial Networks ◽  
Detection Accuracy ◽  
Gas Concentration ◽  
Adversarial Networks

The spontaneous combustion of residual coals in the mined-out area tends to cause an explosion, which is one kind of severe thermodynamic compound disaster of coal mines and leads to serious losses to people's lives and production safety. The prediction and early warning of coal mine thermodynamic disasters are mainly determined by the changes of the index gas concentration pattern in coal mine mined-out areas collected continuously. The time series anomaly pattern detection method is mainly used to reach the state change of gas concentration pattern. The change of gas concentration follows a certain rule as time changes. A great change in the gas concentration indicates the possibility of coal spontaneous combustion and other disasters. To emphasize the features of collected maker gas and overcome the low anomaly detection accuracy caused by the inadequate learning of the normal mode, this paper adopted a method of anomaly detection for time series with difference rate sample entropy and generative adversarial networks. Because the difference rate entropy feature of abnormal data was much larger than that of normal mode, this paper improved the calculation method of the abnormal score by giving different weights to the detection points to enhance the detection rate. To verify the effectiveness of the proposed method, this paper employed simulation models of the mined-out area and adopted coal samples from Dafosi Coal Mine to carry out experiments. Preliminary testing was performed using monitoring data from a coal mine. The experiment compared the entropy results of different time series with the detection results of generative adversarial networks and automatic encoders and showed that the method proposed in this paper had relatively high detection accuracy.

scholarly journals Effect of Phenolic Particles on Mechanical and Thermal Conductivity of Foamed Sulphoaluminate Cement-Based Materials

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3596 ◽  
Author(s):  
Xiuzhi Zhang ◽  
Qing Yang ◽  
Qinfei Li ◽  
Heng Chen ◽  
Guofa Zheng ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Pore Structure ◽  
Dry Density ◽  
Mechanical And Thermal Properties ◽  
Foaming Agent ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Performance Indexes ◽  
Foamed Concrete ◽  
Inorganic Matrix

Foamed concrete materials based on sulpoaluminate cement were prepared by the chemical foaming method. The effects of water–cement ratio, foaming agent, and foaming stabilizer on the mechanical and thermal properties of foamed concrete were studied. Meanwhile, a portion of cement was replaced with foamed phenolic particles to further optimize the performance of foamed concrete; the results show that when the water–cement ratio was 0.53, the foaming agent content was 5%, the foam stabilizer was 1%, and the substitution of phenolic particles was 20%, the performance indexes of foamed concrete were the best. Methods, describing briefly the main methods or treatments applied: dry density was 278.4 kg/m3, water absorption was 19.9%, compressive strength was 3.01 MPa, and thermal conductivity was 0.072 W/(m·K). By the pore structure analysis of the foamed concrete suing Micro-CT, it was found that when the replacement amount of phenolic particles was 20%, the pore size of foamed concrete was relatively uniform, the minimum D90 was 225 μm respectively. The combination of organic and inorganic matrix and optimized pore structure improved the performance of foamed concrete.

Study on Original Coal Seam Permeability Coefficient

2011 ◽  
Vol 361-363 ◽  
pp. 179-182
Author(s):  
Zi Wen Dong ◽  
Qing Jie Qi ◽  
Nan Hu ◽  
Chang Fu Xu ◽  
Hui Niu
Keyword(s):  
Coal Seam ◽  
Water Flow ◽  
Coal Mine ◽  
Permeability Coefficient ◽  
Gas Flow ◽  
Radial Flow ◽  
Gas Permeability ◽  
Coal Seam Gas ◽  
Flow Method

In the case of gas radial flowing in layer-though boring, use the method of draining water gathering gas measured the Gas flow of borehole that there is water flow out from drilling Sometimes,the coal seam gas permeability coefficient is calculated using"Radial Flow Method"and"Optimizing Method,found out the range of 5-3 original coal seam Hongmiao coal mine permeability coefficient is0.007~0.008 m2/(MPa2·d).

scholarly journals Investigation and Optimization of the C-ANN Structure in Predicting the Compressive Strength of Foamed Concrete

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1072 ◽  
Author(s):  
Dong Van Dao ◽  
Hai-Bang Ly ◽  
Huong-Lan Thi Vu ◽  
Tien-Thinh Le ◽  
Binh Thai Pham
Keyword(s):  
Compressive Strength ◽  
Civil Engineering ◽  
Mean Squared Error ◽  
Model Performance ◽  
Absolute Error ◽  
Machine Learning Algorithms ◽  
Coefficient Of Determination ◽  
Dry Density ◽  
Statistical Measures ◽  
Foamed Concrete

Development of Foamed Concrete (FC) and incessant increases in fabrication technology have paved the way for many promising civil engineering applications. Nevertheless, the design of FC requires a large number of experiments to determine the appropriate Compressive Strength (CS). Employment of machine learning algorithms to take advantage of the existing experiments database has been attempted, but model performance can still be improved. In this study, the performance of an Artificial Neural Network (ANN) was fully analyzed to predict the 28 days CS of FC. Monte Carlo simulations (MCS) were used to statistically analyze the convergence of the modeled results under the effect of random sampling strategies and the network structures selected. Various statistical measures such as Coefficient of Determination (R2), Mean Absolute Error (MAE), and Root Mean Squared Error (RMSE) were used for validation of model performance. The results show that ANN is a highly efficient predictor of the CS of FC, achieving a maximum R2 value of 0.976 on the training part and an R2 of 0.972 on the testing part, using the optimized C-ANN-[3–4–5–1] structure, which compares with previous published studies. In addition, a sensitivity analysis using Partial Dependence Plots (PDP) over 1000 MCS was also performed to interpret the relationship between the input parameters and 28 days CS of FC. Dry density was found as the variable with the highest impact to predict the CS of FC. The results presented could facilitate and enhance the use of C-ANN in other civil engineering-related problems.

Distributed gas concentration prediction with intelligent edge devices in coal mine

2020 ◽  
Vol 92 ◽  
pp. 103643
Author(s):  
Yiwen Zhang ◽  
Haishuai Guo ◽  
Zhihui Lu ◽  
Lu Zhan ◽  
Patrick C.K. Hung
Keyword(s):  
Coal Mine ◽  
Gas Concentration ◽  
Concentration Prediction

Numerical Analysis of Water Mist Flow Field for Gas Explosion Suppression in Upper Corner

2011 ◽  
Vol 71-78 ◽  
pp. 4848-4851
Author(s):  
Fan Mao Meng ◽  
Zhi Chao Liu ◽  
Zhi Zhong Liu
Keyword(s):  
Numerical Analysis ◽  
Flow Field ◽  
Coal Mine ◽  
Water Mist ◽  
Gas Explosion ◽  
Gas Concentration ◽  
Methane Gas ◽  
Gas Accumulation ◽  
Explosion Suppression ◽  
Mist Flow

The water mist is an economical and environmental agent for gas explosion suppression. It can be applied in the commonly gas concentration zones and the gas accumulation zones which is difficult to reduce the concentration of methane gas. By numerical analysis, this paper studies the effect of the direction and the number of the nozzles, and the distance form the nozzles to the wall at X direction in upper corner in coal mine. For gas explosion suppression in upper corner, it can use one nozzle which direction is same as the wind and the distance is 2m.

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