scholarly journals Analysis of Dustiness State in a Driven Underground Dog Heading Ventilating by Auxiliary Air-Duct

2020 ◽  
Vol 28 (2) ◽  
pp. 73-77
Author(s):  
Jarosław Brodny ◽  
Magdalena Tutak
Keyword(s):  
Rock Mass ◽  
Research Methodology ◽  
Transport Process ◽  
Coal Dust ◽  
Ventilation System ◽  
Dust Grains ◽  
Movement Trajectories ◽  
Air Stream ◽  
Electrical Devices

AbstractDustiness of the mine atmosphere during carrying out exploitation is one of the most hazardous factors threaten to health and life of employees. Also it is large hazard for all type of mechanical and electrical devices operating in mining headings. Coal dust is also very dangerous due to its possibility of explosion. Currently applied technologies of rock mass mining process, entire transport process of output and applied ventilation system cause that rock and coal dust is presented practically in each of the mining heading. Practically, is impossible to eliminate dust from mining headings. However, one can determine its parameters and potential ways its displacement. In the paper there is presented modeling research methodology of dustiness state in a driven dog heading. Developed model is the basis for this methodology, including the diphase flow of mixture of air and dust in the mining heading. Analysis was performed for real driven dog heading. Based on performed analyses, distributions of particular fraction and movement trajectories of selected dust grains were determined. Developed methodology gives a lot of opportunities for analysis of dustiness state in mining headings and in other compartments. It enables to determine parameters of particular grains and their impact on ventilation parameters of the air stream in the tested headings. Obtained results can also be used to reduce dust hazard.

scholarly journals Influence of the Volumetric Expenditure of Air Supplied to the Longwall Through the “Y” Ventilation System on the Location of an Area at the Risk of an Endogenic Fire

2020 ◽  
Vol 3 (1) ◽  
pp. 206-215
Author(s):  
Magdalena Tutak
Keyword(s):  
Oxygen Content ◽  
Research Methodology ◽  
Ventilation System ◽  
The Self ◽  
Hard Coal ◽  
Heating Process ◽  
Air Velocity ◽  
Self Heating ◽  
Air Stream ◽  
Endogenous Fire

AbstractIn the case of longwall ventilation, in the underground hard coal mines, a phenomenon related to the migration of a certain amount of the air stream supplied to the longwall deep into goaf zones occurs. One of the wall ventilation systems, in which this phenomenon is quite intense, is the so called “Y” ventilation system. This migration is immensely unfavorable because it can lead to the self-heating process of coal left in a goaf and, consequently, to an endogenous fire. Such a fire is a great threat to both the safety and continuity of operation processes. For this reason, various activities are undertaken to prevent such a fire from occurring in goaf zones. One solution is a method presented in this article. It aims at determining an area in goaf zones, where an endogenous fire may occur. The study focused on the longwall ventilated with the Y system. This area was determined based on two criteria, namely air velocity and oxygen content. The study was carried out for various volumes of air supplied to the longwall. Therefore, the purpose of the study was to develop research methodology and determine the location of an area at the risk of an endogenous fire. The location of this area was determined for three different volume expenditures of air supplied to the longwall ventilated with the Y system.

Three Dimensional Simulation of Ventilation Flow Through a Solar Windcatcher

2019 ◽  
Author(s):  
Peter Abdo ◽  
Rahil Taghipour ◽  
B. P. Huynh
Keyword(s):  
Natural Ventilation ◽  
Air Flow ◽  
Ventilation System ◽  
Three Dimensional ◽  
Windward Side ◽  
Efficient Design ◽  
Indoor Space ◽  
Wind Speeds ◽  
Air Stream ◽  
Stack Ventilation

Abstract Natural ventilation is the process of supplying and removing air through an indoor space by natural means. There are two types of natural ventilation occurring in buildings: winddriven ventilation and buoyancy driven or stack ventilation. The most efficient design for natural ventilation in buildings should implement both types of natural ventilation. Stack ventilation which is temperature induced is driven by buoyancy making it less dependent on wind and its direction. Heat emitted causes a temperature difference between two adjoining volumes of air, the warmer air will have lower density and be more buoyant thus will rise above the cold air creating an upward air stream. Combining the wind driven and the buoyancy driven ventilation will be investigated in this study through the use of a windcatcher natural ventilation system. Stack driven air rises as it leaves the windcatcher and it is replaced with fresh air from outside as it enters through the positively pressured windward side. To achieve this, CFD (computational fluid dynamics) tool is used to simulate the air flow in a three dimensional room fitted with a windcatcher based on the winddriven ventilation alone, buoyancy driven ventilation alone, and combined buoyancy and winddriven ventilation. Different wind speeds between 0 up to 2.5 m/s are applied and the total air flow rate through the windcatcher is investigated with and without temperature of 350 K applied at the windcatcher’s outlet wall. As the wind speed increased the efficiency of the solar windcatcher decreased.

scholarly journals The Influence of the Permeability of the Fractures Zone Around the Heading on the Concentration and Distribution of Methane

2019 ◽  
Vol 12 (1) ◽  
pp. 16 ◽  
Author(s):  
Magdalena Tutak
Keyword(s):  
Ventilation System ◽  
Organizational Factors ◽  
Primary Objective ◽  
Test Results ◽  
Ansys Fluent ◽  
New Approach ◽  
Model Based ◽  
Coal Beds ◽  
Air Stream ◽  
Fluent Software

One of the main problems related to the excavation of dog headings in coal beds is the emission of methane during this process. To prevent the occurrence of dangerous concentration levels of this gas, it is necessary to use an appropriate ventilation system. The operation effectiveness of such a system depends on a number of mining, geological, technical and organizational factors. One of them includes the size and permeability of the fractures zone formed around the excavated dog heading. The primary objective of the paper is to determine the influence of this zone on the ventilation parameters, including the concentration and distribution of methane in the excavated dog heading. In order to achieve the assumed objective, multivariate model-based tests were carried out, which reproduce a real-world dog heading. Literature data and test results in actual conditions were used to determine the size and permeability of the fractures zone around the excavated heading. These data served as the basis to develop a model of the region under analysis and adopt boundary conditions. The analyses were carried out for four permeability values of the fractures zone and for two volumetric flow rates of the air stream supplied to the heading. The results were used to determine the influence of the fractures zone on the distribution and concentration of methane in the heading under analysis. The model-based tests were performed using ANSYS Fluent software. The idea to take into account the fractures zone around the heading represents a new approach to the analysis of ventilation parameters in underground mine headings. The results clearly indicate that this zone affects the ventilation parameters in the heading, including the distribution and concentration of methane. The knowledge obtained from the tests should be used to optimize the ventilation process of dog headings. All authors have read and agreed to the published version of the manuscript.

scholarly journals Behavior Characteristics of Hazardous Gas and Scattering Coal Dust in Coal Storage Sheds

2021 ◽  
Vol 11 (24) ◽  
pp. 11771
Author(s):  
Mok-Lyang Cho ◽  
Ji-Soo Ha ◽  
Tae-Kwon Kim
Keyword(s):  
Carbon Monoxide ◽  
Natural Ventilation ◽  
Coal Dust ◽  
Retaining Wall ◽  
Ventilation System ◽  
Spontaneous Ignition ◽  
Flow Stagnation ◽  
Measurement Results ◽  
Behavior Characteristics ◽  
And Behavior

This study has comprehensively analyzed the ventilation system of an indoor coal storage shed using computational fluid dynamics (CFD). In addition, the effects of the plan to improve the ventilation system were investigated by synthesizing the results. First, the velocity of inlet wind entering through the natural ventilation system was measured. Then, the concentration of carbon monoxide inside the coal storage shed was measured at the spontaneous combustion of coal. The boundary conditions were set using the measurement results. The characteristics of carbon monoxide concentration, ventilation volume, and behavior of scattering dust were analyzed. According to the CFD analysis results, the upper recirculation strength increased as the flow rate of external air increased. The flow-stagnation area occurred on the center wall. In particular, the concentration of carbon monoxide was high in the flow-stagnation area. When the inflow velocity was 2.0 m/s, a risk of 30 ppm or more occurred in the area near the second-floor workspace and central retaining wall. When ventilation dropped sharply, coal dust emissions decreased to 14.5%. Thus, ventilation must be secured by installing a natural ventilation system, in case spontaneous ignition occurs in many cells or the ventilation sharply decreases. Finally, in order to improve the ventilation system, the effect on the additional installation of natural ventilation and the use of mobile blowers was analyzed. Finally, in order to improve the ventilation system, the effect on the additional installation of natural ventilation and the use of mobile blowers was analyzed. As a result of the analysis, we concluded that using a mobile blower is more effective than a method of additionally installing a natural ventilation device. Carbon monoxide may be locally diluted, and ventilation volume additionally secured.

THE EFFECT OF TEMPERATURE OF ROCKS ON MICROCLIMATIC CONDITIONS IN LONG GATE ROADS AND GALLERIES IN COAL MINES

2014 ◽  
Vol 59 (1) ◽  
pp. 189-216 ◽  
Author(s):  
Janusz Cygankiewicz ◽  
Józef Knechtel
Keyword(s):  
Rock Mass ◽  
Coal Extraction ◽  
Effect Of Temperature ◽  
Coal Oxidation ◽  
Temperature Changes ◽  
Air Stream ◽  
Finite Differences Method ◽  
Microclimatic Conditions ◽  
Rock Mass Fracturing

Abstract The aim of this study was to examine the effect of the temperature of surrounding rocks on enthalpy and temperature of air flowing along several model mine workings. Long workings surrounded by non- -coal rocks as well longwall gates surrounded by coal were taken into consideration. Computer-aided simulation methods were used during the study. At greater depths the amount of moisture transferred into a mine working from the rock mass is two orders of magnitude smaller than the moisture that comes from external (technological) sources, mainly from coal extraction-related processes, therefore in the equation describing temperature changes only the terms representing the flux of heat from rocks were included. The model workings, for calculation purposes, were divided into sections, 50 m in length each. For each of the sections temperature of its ribs and temperature and stream of enthalpy of air flowing along it were calculated with the use of the finite differences method. For workings surrounded by non-coal rocks two variant calculations were carried out, namely with or without technological sources of heat. For coal surrounded workings (longwall gates) a new method for determination of heat from coal oxidation was developed, based on the findings by Cygankiewicz J. (2012a, 2012b). Using the results of a study by J.J. Drzewiecki and Smolka (1994), the effects of rock mass fracturing on transfer of heat into the air stream flowing along a working were taken into account.

EVALUATING RELATIONSHIP OF SELF-BURNING OF BREEDS WITH DEFORMATION PROCESSES IN THE COMBINED DEVELOPMENT OF SUMMARY ORE DEPOSITS

2020 ◽  
Vol 2 (1) ◽  
pp. 329-341
Author(s):  
M.V. RYLNIKOVA ◽  
◽  
D.N. RADCHENKO ◽  
G.I. AYNBINDER ◽  
E.N. ESINA ◽  
...  
Keyword(s):  
Rock Mass ◽  
Spontaneous Combustion ◽  
Atmospheric Oxygen ◽  
Ventilation System ◽  
Ore Deposits ◽  
Open Pit ◽  
Environmental Damage ◽  
Mining Operations ◽  
Deformation Processes ◽  
Relationship Of

For decades and centuries, spontaneous combustion of minerals occurs, which leads to significant material, economic and environmental damage. Under anthropogenic impact on the subsoil, conditions are created for the active development and opening of cracks as a result of deformation of the rock mass, under the influence of its open and underground parttime work. as a result, the emergence of conditions for the active penetration of atmospheric oxygen from the mine ventilation system and the surface atmosphere along the cracks formed as a result of deformation to sulfur-containing minerals of ores and rocks, prone to oxidation and spontaneous combustion. The mechanism of spontaneous combustion of pyritic rocks in the rock mass during the development of deposits is analyzed. It is proved that in the combined development of pyrite ore deposits, exogenous physicochemical processes must be considered in conjunction with geomechanical processes due to the development of mining operations beyond the open pit contour, aerogasdynamic determined by the method, scheme and ventilation system of an underground mine, as well as thermo-physical processes occurring as a result of exothermic oxidation of sulfides...

scholarly journals The effect of methane emission on air distribution in potash mine production units

2021 ◽  
Vol 6 ◽  
pp. 87-97
Author(s):  
Aleksandr Nikolaev ◽  
Keyword(s):  
Rock Mass ◽  
Point Source ◽  
Methane Emission ◽  
Air Distribution ◽  
Mine Production ◽  
Air Stream ◽  
Mine Workings ◽  
Methane Distribution ◽  
Potash Mine ◽  
Air Circulation

Introduction. It has been found that due to light gas (including methane) emission in rooms under development, there develops an additional natural draught between the mine workings. The calculation has shown that methane emission from the rock mass conditions the low value of the additional natural draught. However, even minor additional natural draught interacting with a thermal drop of pressure caused by temperature rise in the conveyor shaft changes the direction of the delivery air stream. While in up the dip blocks and panels the resultant natural draught promotes ventilation, in the down the dip production units it prevents air circulation in the required direction. Research methods. The methods and results of calculating the value and direction of the natural draught for real panels of potash mines at the Upper Kama potash deposit under various conditions have been presented together with the simulation observations of methane distribution in the room with a point source of emission. Results. Model analysis has shown that even under the low amount of gas emission out of the point source in the blind room (of a hole drilled in the roof), the concentration of gas in the gas-air mixture entering the belt heading reaches 2%. Conclusions. To ensure the safety of mining and reduce the risk of emergency when calculating the volume of air required to ventilate the production units, the dynamics of methane emission out of the rock mass should be taken into account as well as its further distribution across the mine workings.

scholarly journals Numerical Study of the Respirable Coal Dust Removal Performance of a Vortex Ventilation System at an Excavation Face

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2449 ◽  
Author(s):  
Xiaofei Liu ◽  
Ping Chang ◽  
Enyuan Wang ◽  
Zhenguo Zhang ◽  
Shuai Yang
Keyword(s):  
Numerical Study ◽  
Coal Dust ◽  
Ventilation System ◽  
Dust Control ◽  
Dust Removal ◽  
Two Phase ◽  
Fluid Behavior ◽  
Comparison Results ◽  
High Concentrations ◽  
Ventilation Systems

Coal dust is one of the most serious issues in coal mines. The miners at an excavation face have a high potential for exposure to high concentrations of coal dust. The main method for removing coal dust is by ventilation. To better control the coal dust at the excavation face, it is important to understand the coal dust movement patterns and distribution characteristics. This paper used the computational fluid dynamics (CFD) approach to simulate coal dust movement under two different ventilation systems. The Eulerian-Lagrange method was used to study the gas‒solid two-phase fluid behavior. The coal dust concentration distributions under the two ventilation systems are presented and further compared. From the comparison results, it is found that a vortex ventilation system has better coal dust removal performance. This ventilation system is recommended for excavation for better coal dust control and miners’ health protection.

scholarly journals Bacteriological evaluation of a mobile laminar cross-flow unit for surgery, under laboratory circumstances

1976 ◽  
Vol 76 (1) ◽  
pp. 1-10 ◽  
Author(s):  
D. van der Waaij ◽  
N. Wiegersma ◽  
J. Dankert
Keyword(s):  
Escherichia Coli ◽  
Ventilation System ◽  
Cross Flow ◽  
Flow Unit ◽  
Concentrated Suspensions ◽  
Air Stream ◽  
Bacterial Aerosol ◽  
The Cross ◽  
Bacteriological Evaluation

SUMMARYA mobile laminar cross-flow unit for surgery has been evaluated by the use of an experimental bacterial aerosol of Escherichia coli in different concentrations, generated at several different sites. A separate ventilation system, mounted underneath the table, produced an almost downward directed curtain of sterile air along both sides of the table. When the velocity of the air stream, discharged by the cross-flow unit, was adjusted at 0·50 m./sec. at 2 m. from the filter face (at the head end of the operation table), the surface of the table could be maintained free of bacterial settling, even after aerosolization of heavily concentrated suspensions of 108 bacteria/ml. at different sites outside the enclosure and underneath the table as well.

scholarly journals Considerations Concerning the Stream of Heat Transferred from Rock Mass Into Mine Ventilation Air and the Utilization of this Heat by Means of Air Cooling Installation / Úvaha Týkající Se Přestupu Tepla Z Horninového Masívu Do Důlního Ovzduší A Použití Chladicích Zařízení K Využití Tohoto Tepla

2011 ◽  
Vol 57 (2) ◽  
pp. 1-12
Author(s):  
Józef Knechtel
Keyword(s):  
Rock Mass ◽  
Thermal Energy ◽  
Mine Ventilation ◽  
Hot Water ◽  
Air Cooling ◽  
Mining Operations ◽  
Surface Level ◽  
Hot Air ◽  
Air Stream ◽  
Surface Condensation

Abstract This paper deals with the feasibility of utilization of the heat carried away with the air stream ventilating a mine after closing down mining operations. The problem is that, although the temperature of air flowing underground is rather high (above 35°C), the air temperature at the surface level drops to about 25°C. For that reason it was proposed to cool down the hot air underground and to transport the hot water from cooling machines to the surface level. However, such a solution is not realistic in closed-down mines. So, another idea was considered consisting in exploiting the thermal energy of the exhaust air stream in functioning mines. Further the cooling potential of Polish mines was surveyed. It emerged that for the mines with an active cooling potential in the range of a couple of MW it can be economically viable to transfer the gained thermal energy released due to surface condensation and to use that energy for communal heating.

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