Wei Min Cheng

Study and Prevention on the Diffusion Rule of Dust Pollution in the Coal Mine Whole-Rock Fully Mechanized Workface

The mathematical model of solving two-phase flow of gas and dust particles was built by established the k-ε-Θ-kp equation. Moreover, by using FLUENT software, the diffusion rule of dust pollution in the whole-rock fully mechanized workface was researched with different air-draft amount. The result showed that when the air-draft amount increased from 320m3/min to 600m3/min, de-dust ability of extraction fan drum is gathering strength, pervasion intensity of producing dust is continuously decreased in tunneling place. The simulation results of each measuring point are basically consistent with the field measurement results.

Numerical Simulation Research on Gas-Dust Flow Field of Forced-Exhausted Hybrid Ventilation in Whole Rock Mechanized Heading Face

Euler-Euler two-fluid model was used to construct control equations of gas-solid two-phase flow, based on SIMPLE algorithm of collocated grid and FLUENT software, the pressure distribution of air-flowing field and dust field diffusion in fully-mechanized excavation face with different air-draft volume were simulated. The results show that with the increase of exhausted dust ability, diffusion intensity of producing dust pollution in driving head constantly decreases. Compared to air-draft volume of 320m3/min, when it is 600m3/min, the average dust concentration at the driver and whole section positions respectively decrease 51.28% and 56.51%, and high-concentration dust diffusion distance of the other workers position section decrease from 13.6m to 8.5m. Engineering Application indicates that the measured dust concentration is basically anastomosed with simulation result. When air-draft volume of dedusting fan is 600m3/min and dust control system with air curtain formed by forced fan drum is used, the dedusting rates of total coal dust and respirable dust on spot are respectively 95.1% and 96.1%, which achieves a great dedusting effect.

Simulation Experimental Study on the Permeability of Coal Rock in Deep Mine

By means of MTS electro-hydraulic servo system, specimens from deep coal mine rock are conducted the permeability characteristics experiment under the condition of the stress-strain process and high pore-water pressure, also the results show that both the permeability rate and volumetric strain curves are V shaped, which link the dynamic changes of the microscopic fracture porosity and corresponds with the stress-strain. Meanwhile, under certain external conditions, whether the change of the pore-water pressure can improve the permeability properties or not, it depends on the critical threshold, moreover, the permeability properties under pore-water pressure higher than critical threshold have been improved several times than that at low pore-water pressure, and the peak of strain-permeability rate has a corresponding change with the peak of stress-strain curve, which shows a hysteretic characteristic. The higher the pore-water pressure is, the lower peak strength is needed, the more distinctive effects of dilatation emerge, and the more strain is needed for the appearance of permeability peak, This article provides the basis for the employment of high pore-water pressure to improve the permeability and disaster prevention of coal rock water injection.

Experimental Study on Coal Pore Characteristic Based on Cryogenic Liquid Nitrogen Method

In view of pore distribution in coal, this paper applies BJH method that is based on the cylinder theory and adopts cryogenic liquid nitrogen adsorption method to carry out experimental investigation on pore structure of No.3U coal seam in Sanhekou Coalmine, obtaining the fact that pore structure of No.3U coal is complicated, the cool pores are mostly flask pores, others are the parallel plate pores with one end closed and the cylinder pores with one end closed; According to the distribution of BJH pore volume and pore surface area, ultramicropores with apertures less than 10 nm are among the most; Then obtain the average BET specific surface area, the distribution of BJH pore volume and pore area, average single-point total pore volume and most probable pore .etc, which conducive to a better understanding of the micropores characteristic of coal.

Wall-Attachment Fan Drum Enclosed Dust Removal Theory and Technology of Mechanized Working Face

FLUENT software and SIMPLE algorithm which was based on parity grid was used to carry out the numerical simulation of spraying dust gas-particle two-phase flow field of the mechanized working face with a single pressure pumping hybrid ventilation system. The dust distribution law of the mechanized working face was mastered and the main dust prevention area was determined to be the middle of the roadway and wall-attachment fan drum enclosed dust removal system of mechanized working face was also planned to be established according to the simulation result. It had been proved that fully-mechanized coal winning machine enclosed dust removal system had a large advantage in reducing dust by computer simulation and field application, the dust suppression effect was remarkable.

The Division of No 1304 Face in Tangkou Coal Mine and a Case Analysis

Based the analysis of the “3 zones” theory and index of spontaneous combustion in the mined out area, six measured points under which there are air sample collection probe and temperature sensor measuring the air composition and temperature of the mined out area of No 1304 face are arranged along both crossheadings of the mined out area in order to divide the “3 zones” of spontaneous combustion with the combination of the mining situation of No 1304 face in Tangkou coal mine. This present study mainly measures and analyzes the concentration of O2 and the temperature change and takes advantage of the Matlab and Excel to fit the concentration of O2 to determine the range of “3 zones”of spontaneous combustion in NO. 1304 face. Meanwhile, the concentration of CO is also measured and analyzed to determine the most prone location to fire of No. 1304.

Numerical Simulation Study on Air-Flow Migration Law about Vortex Air Curtain of Plane Wall Fan Drum

Vortex air curtain of plane wall fan drum can control the diffusion of air stripping dust effectively. In order to solve the high-concentration dust problem in fully mechanized excavation face, formation mechanism of vortex air curtain was analyzed. According to fluid mechanical control equations of gas phase flow, mathematical model was established to solve air migration law of vortex air curtain in fully mechanized excavation face. By using Simple algorithm based on collocated grid and fluent software, numerical simulation of air spatial migration law of closed-end dust control in fully mechanized excavation face was carried out. The simulation results show that vortex air curtain dust control system can form dust control fan drum along driving head to the front of the roadheader driver. According to the simulation results and actual conditions of working face field, vortex air curtain suction dust control system consisted of plane wall fan drum and exhausted dust purification device in fully mechanized excavation face was designed, and after it was applied in fully mechanized excavation face, the dust concentration decreased effectively in the working face field.

Regularity of Dust Distributing in Fully Mechanized Caving Face and Negative Pressure Spray Dust-Settling Technology

The mathematical model of solving two-phase flow of gas and dust particles was built by established the k-ε equation. Moreover, by basing on Eulerian-Lagrangian model and using FLUENT software, the diffusion rule of dust pollution in full-mechanized caving face was confirmed. Based on negative pressure spray dust-settling mechanism, negative pressure spray technology was developed between hydraulic supports, in drawing opening position and shearer, and it was determined by the optimal spray pressure for 4 MPa. After negative pressure spray technology was applied in fully mechanized caving face, the dust concentration was down significantly.

Numerical Simulation of Eddy Air-Curtain Dust Controlled Flow Field in Hard Rock Mechanized Driving Face

The author established the mathematical model of single-phase flow of gas based on the k-ε two-equation model and numerically simulated the eddy air-curtain dust controlled flow field in hard rock mechanized driving face with the help of FLUENT software.The result showed that, after all the pressure ventilation blown out by the radial clearance of mural cylinder, a full-face eddy air-curtain flow field is formed at the roadway section, forming the air-curtain dust controlled flow field that presses the tunneling place equally in front of the driver of roadheader. After the application of the development of new light polymer materials radial cylinder eddy air-curtain dust controlled system was adopted in hard rock mechanized driving face of north conveyor main roadway, reducing the local dust concentration effectively.

Research of Ventilation and Dust Removal Technology for Whole Rock Fully-Mechanized Excavation Face

The whole rock fully-mechanized excavation with big cross section, high rock hardness and strong cutting intensity of fully-mechanized coal winning machine has a higher dust concentration than coal roadway excavation, so ventilation dust removal technology is in need in whole rock face. Based on the dust migration and distribution numerical simulation in whole rock tunnel excavation, optimization design of long pressing and short pumping hybrid ventilation and dust removal system were carried out. Eventually, the comprehensive dust prevention measures with air curtain closing dust source, dust electromotor exhausting dust and retaining curtain capturing dust were realized in this paper, which achieved a good removal efficiency of dust.