Gas explosion characteristics and spray control mechanism in underground square.

The spray system mechanism during a gas explosion in an underground square pipeline is complex. In this paper, the underground square of Fuxin City is selected as the research object. FLACS numerical simulation software is used to analyze the spatial and temporal distribution characteristics of a gas explosion in an underground square pipeline with an unopened spray system using combustion and combustion rate models. Different spray pressures were compared and analyzed to determine the optimal spray control pressure, and the spray system mechanism was clarified. The results revealed that the gas explosion overpressure is divided into the overpressure gentle, overpressure rising, and overpressure decay stages, corresponding to a trend of rapid growth and slow decline. The influence of spray pressure on the gas explosion exhibits a promotion-inhibition-promotion trend, corresponding to 0-0.2 MPa, 0.2-0.6 MPa, and 0.6-1.6 Mpa, respectively. The peak overpressure and overpressure propagation rates are the lowest at 0.6 MPa, and the explosion suppression effect is the most pronounced. The spray system mechanism varies with the explosion overpressure stages. Generally, the time to peak value, that is, the peak time, the overall duration of the explosion, and the duration of the explosion stage decrease, whereas the peak explosion overpressure decreases.

Prediction method of coal mine gas occurrence law based on multi-source data fusion.

To improve the prediction accuracy and time-consuming of coal mine gas occurrence law (OL), a new prediction method based on multi-source data fusion is proposed in this paper. Firstly, the method obtains the data of coal mine gas OL, determines the key data required in prediction through decision matrix, and preprocesses the data to reduce the influence of regular noise data. This paper analyzes the basic principle of multi-source data fusion, constructs the prediction model of coal mine gas OL with this technology, takes the optimal value of weighting factor as the input value of the model, and completes the design of coal mine gas OL prediction method based on multi-source data fusion. The experimental results show that the accuracy of this method can reach 98%, while that of the other two traditional methods is lower than the existing methods. This method has high accuracy and efficiency in predicting the coal mine gas OL.

Study on Multipoint and Zoning Coordinated Prevention of Gas and Coal Spontaneous Combustion in Highly Gassy and Spontaneous Combustion-Prone Coal Seam.

Coal spontaneous combustion in gob often induces gas explosion accidents. To solve the frequent occurrence of gas and coal spontaneous combustion (GCSC) symbiotic disaster of highly gassy and spontaneous combustion-prone short-distance coal seams, the stope space of a complex working face formed by the old gob above and the coal seam mined below in Hengda Mine is divided into three zones, a completely connected zone, a partially connected zone, and an unconnected zone, according to the connectivity degree of fractures. A numerical model is established to study the relationship between gas drainage and coal spontaneous combustion. The effects of ventilation flux in the working face, gas drainage flow in the upper corner, gas drainage flow in the high-drainage roadway, fracture grout sealing, and nitrogen injection flow on the airflow field, gas concentration field, oxygen concentration field, and the temperature field in the completely connected and partially connected zones are analyzed. A multifactor interaction relationship under the conditions of ventilation, gas drainage, and nitrogen injection is revealed, and a multipoint and zoning coordinated prevention method for the GCSC symbiotic disaster is proposed. On the basis of the proposed method, the gas drainage flow in the high-drainage roadway and corner pipe of 5333(B) working face are determined to be 45.4 and 112.1 m3/min, respectively, and the total nitrogen injection flow in the upper gob and the lower gob are 350 and 640 m3/h, respectively. The upper corner gas concentration and the return roadway maximum gas concentration are lower than 0.8% during the stoping process, and there is no spontaneous combustion risk of the gob residual coal, thus reducing the greenhouse gas emission and realizing safety mining. This study is conducive to facilitate the realization of the goal of carbon neutrality and peak carbon dioxide emissions.