scholarly journals Numerical Model to Assess the State and Increase of Temperatures in Underground Mine Galleries: A Tool to Support Heat Recovery Projects

2021 ◽  
Vol 4 (1) ◽  
pp. 110-118
Author(s):  
Vitor Colombo ◽  
Maria Lurdes Dinis ◽  
José Soeiro de Carvalho
Keyword(s):  
Numerical Model ◽  
Heat Recovery ◽  
Underground Mining ◽  
Abandoned Mines ◽  
Heat Extraction ◽  
Thermodynamic Efficiency ◽  
Lower Grade ◽  
Heat Sources ◽  
Geothermal Systems ◽  
Mining Operations

Underground mining is facing growing challenges related to the need to mine deeper and at higher temperatures, to operational expenditures associated with energy consumption, lower grade ores, environmental constraints, and social pressures. In this scenario, a new numerical model is proposed to estimate temperature increase inside mining galleries to provide specific criteria for heat recovery projects, which may consider heat extraction from abandoned mines using closed-loop geothermal systems or from operating mines using the exhaust ventilation air. This model couples different approaches from previous models and include key parameters unemployed until this moment, such as wall roughness and velocity profile modeling, what would allow for a more realistic estimation of convective heat transfer phenomena, which is critical to predicting heat exchange in ventilation air due to the turbulent nature of the airflow. The model also includes other heat sources that could be present inside galleries and should be accounted for, such as machinery, once the heat dissipated to the environment might be substantial depending on the equipment and gallery geometry. The general intention of this project is to account for every heat source that may contribute to increasing the temperature inside the gallery, so it becomes tangible to harness as much heat energy as possible, preventing energetic losses and stimulating an increase of thermodynamic efficiency in underground mining operations. The model is not validated yet with real temperature data, but preliminary results agree with the ones from previous models.

scholarly journals On the Conceptual Design of Novel Supercritical CO2 Power Cycles for Waste Heat Recovery

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 370 ◽  
Author(s):  
Giovanni Manente ◽  
Mário Costa
Keyword(s):  
High Temperature ◽  
Heat Source ◽  
Thermal Efficiency ◽  
Supercritical Co2 ◽  
Heat Recovery ◽  
Waste Heat ◽  
Heat Extraction ◽  
Heat Sources ◽  
Partial Heating ◽  
Single Flow

The supercritical CO2 power cycle (s-CO2) is receiving much interest in the utilization of waste heat sources in the medium-to-high temperature range. The low compression work and highly regenerative layout result in high thermal efficiencies, even at moderate turbine inlet temperatures. The capability of heat extraction from the waste heat source is, however, limited because the heat input takes place over a limited temperature range close to the maximum cycle temperature. Accordingly, novel s-CO2 layouts have been recently proposed, aimed at increasing the heat extraction from the heat source while preserving as much as possible the inherently high thermal efficiency. Among these, the most promising ones feature dual expansion, dual recuperation, and partial heating. This work concentrates on the conceptual design of these novel s-CO2 layouts using a systematic approach based on the superimposition of elementary thermodynamic cycles. The overall structure of the single flow split with dual expansion (also called cascade), partial heating, and dual recuperated cycles is decomposed into elementary Brayton cycles to identify the building blocks for the achievement of a high performance in the utilization of waste heat sources. A thermodynamic optimization is set up to compare the performance of the three novel layouts for utilization of high temperature waste heat at 600 °C. The results show that the single flow split with a dual expansion cycle provides 3% and 15% more power compared to the partial heating and dual recuperated cycles, respectively, and 40% more power compared to the traditional single recuperated cycle used as the baseline. The separate evaluation of thermal efficiency and heat recovery effectiveness shows the main reasons behind the achievement of the highest performance, which are peculiar to each novel layout.

scholarly journals Potential influence of sewer heat recovery on in-sewer processes

2019 ◽  
Vol 80 (12) ◽  
pp. 2344-2351 ◽  
Author(s):  
Mohamad Abdel-Aal ◽  
Raffaella Villa ◽  
Natalia Jawiarczyk ◽  
Luca Alibardi ◽  
Henriette Jensen ◽  
...  
Keyword(s):  
Hydrogen Sulphide ◽  
Urban Areas ◽  
Heat Recovery ◽  
Heat Extraction ◽  
Heat Sources ◽  
Sewer Pipes ◽  
Biochemical Processes ◽  
Study Approach ◽  
Heat Demand

Abstract Heat recovery from combined sewers has a significant potential for practical renewable energy provision as sources of heat demand and sewer pipes are spread across urban areas. Sewers are continuously recharged with relatively hot wastewater, as well as interacting with heat sources from surrounding air and soil. However, the potential effects of modifying sewage temperature on in-sewer processes have received little attention. The deposition of fats, oils and greases (FOGs) and hydrogen sulphide formation are biochemical processes and are thus influenced by temperature. This paper utilises a case study approach to simulate anticipated temperature reductions in a sewer network due to heat recovery. A laboratory investigation into the formation of FOG deposits at temperatures varying between 5 °C and 20 °C provided mixed results, with only a weak temperature influence, highlighting the need for more research to fully understand the influence of the wastewater composition as well as temperature on FOG deposit formation. A separate modelling investigation into the formation of hydrogen sulphide when inflow temperature is varied between 5 °C and 20 °C showed considerable reductions in hydrogen sulphide formation. Hence, heat extraction from sewers could be a promising method for managing some in-sewer processes, combined with traditional methods such as chemical dosing.

scholarly journals Geological CO2 quantified by high-temporal resolution stable isotope monitoring in a salt mine

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Alexander H. Frank ◽  
Robert van Geldern ◽  
Anssi Myrttinen ◽  
Martin Zimmer ◽  
Johannes A. C. Barth ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Underground Mining ◽  
Stable Carbon Isotope ◽  
Underground Mines ◽  
Background Concentration ◽  
High Temporal Resolution ◽  
Salt Mine ◽  
Gas Migration ◽  
Mining Operations ◽  
Anthropogenic Contributions

AbstractThe relevance of CO2 emissions from geological sources to the atmospheric carbon budget is becoming increasingly recognized. Although geogenic gas migration along faults and in volcanic zones is generally well studied, short-term dynamics of diffusive geogenic CO2 emissions are mostly unknown. While geogenic CO2 is considered a challenging threat for underground mining operations, mines provide an extraordinary opportunity to observe geogenic degassing and dynamics close to its source. Stable carbon isotope monitoring of CO2 allows partitioning geogenic from anthropogenic contributions. High temporal-resolution enables the recognition of temporal and interdependent dynamics, easily missed by discrete sampling. Here, data is presented from an active underground salt mine in central Germany, collected on-site utilizing a field-deployed laser isotope spectrometer. Throughout the 34-day measurement period, total CO2 concentrations varied between 805 ppmV (5th percentile) and 1370 ppmV (95th percentile). With a 400-ppm atmospheric background concentration, an isotope mixing model allows the separation of geogenic (16–27%) from highly dynamic anthropogenic combustion-related contributions (21–54%). The geogenic fraction is inversely correlated to established CO2 concentrations that were driven by anthropogenic CO2 emissions within the mine. The described approach is applicable to other environments, including different types of underground mines, natural caves, and soils.

scholarly journals COMPREHENSIVE NUMERICAL MODEL FOR THE ANALYSIS OF POTENTIAL HEAT RECOVERY SOLUTIONS IN A CERAMIC INDUSTRY

2021 ◽  
pp. 100080
Author(s):  
M. Venturelli ◽  
D Brough ◽  
M. Milani ◽  
L. Montorsi ◽  
Hussam Jouhara
Keyword(s):  
Numerical Model ◽  
Heat Recovery ◽  
Ceramic Industry

A Review of Technical Potential for Coal Production and Coal Degasification – A Conventional Source of Methane – In Nigeria

2003 ◽  
Vol 14 (1) ◽  
pp. 59-67
Author(s):  
Adepo Jepson Olumide ◽  
Ayodele Charles Oludare ◽  
Balogun Olufemi
Keyword(s):  
Coal Seam ◽  
Fossil Fuels ◽  
Underground Mining ◽  
Simple Calculation ◽  
Gas Content ◽  
Gelling Agent ◽  
Coal Bed ◽  
Natural State ◽  
Mining Operations ◽  
Inorganic Matter

Coal, a solid fuel in its natural state has been identified as one of the world's major fossil fuels. It is a compact, stratified mass of mummified plant debris interspersed with smaller amounts of inorganic matter buried in sedimentary rocks. The use of coal as an energy source can be dated back to the prehistoric times. Methane is associated with many if not all coal seams, and is the dreaded “fire damp” responsible for many pit explosions. Coal mines are designed to vent as much methane as possible. It is present in the pores of coal under pressure, released during mining operations and can be extracted through vertical well bores. This paper highlights the fact that pipeline- quality methane can be extracted economically from coal seems before and during underground mining operations. The stimulation method involves hydraulic fracturing of the coal seam by using water, sand and, a gelling agent in a staged and alternating sand/and no sand sequence. The purpose is to create new fractures in the coal seam(s). The cleating of the coal helps to determine the flow characteristics of the coal formation and is vital in the initial productivity of a coal-methane well. The simple calculation of gas-in-place is achieved by multiplying the gas content of the coal by net coal thickness, the density, and the aerial extent of the drainage. The method is claimed to be suitable for use in Nigeria and potential sites for coal bed methane extraction in Nigeria are identified.

scholarly journals TECHNOLOGIES, SYSTEMS, AND EQUIPMENT FOR WASTEWATER HEAT UTILIZATION (REVIEW)

2020 ◽  
Vol 42 (3) ◽  
pp. 39-46
Author(s):  
B.І. Basok ◽  
M.P. Novitska ◽  
S.M. Goncharuk
Keyword(s):  
Heat Recovery ◽  
Scientific Literature ◽  
Residential Buildings ◽  
Heat Extraction ◽  
Utilization Review ◽  
Heat Utilization ◽  
Factors Influencing ◽  
Main Factors ◽  
Political Economic

The paper analyzes research, technologies, and equipment related to wastewater heat utilization systems. The main factors influencing the development of the industry and the implementation of such systems are given. Such factors include: social, political, economic, technological, legal and environmental. The classification of technologies and equipment for wastewater heat utilization according to the place of heat extraction is given. Namely, low potential wastewater heat can be collected at the treatment plants, in sewer collectors leading to treatment plants and directly in houses. The paper describes the available research in the scientific literature on these three categories The global scientific community is working to create efficient wastewater heat recovery systems. The environmental situation requires greater use of wastewater recovery systems. An important issue is to increase awareness and education of the population, as this approach will increase the degree of implementation of wastewater heat utilization systems in residential buildings.

Analysis of influencing factors of heat extraction from enhanced geothermal systems considering water losses

Energy ◽  
2016 ◽  
Vol 115 ◽  
pp. 274-288 ◽  
Author(s):  
Wen-Long Cheng ◽  
Chang-Long Wang ◽  
Yong-Le Nian ◽  
Bing-Bing Han ◽  
Jian Liu
Keyword(s):  
Influencing Factors ◽  
Heat Extraction ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Water Losses

Comprehensive Assessment of Working Conditions and Occupational Disease Rates at Mining and Metallurgical Enterprises

2021 ◽  
pp. 114-119
Author(s):  
A.G. Chebotarev ◽  
D.D. Sementsova
Keyword(s):  
Ferrous Metallurgy ◽  
Working Conditions ◽  
Occupational Diseases ◽  
Underground Mining ◽  
Working Environment ◽  
Aluminum Production ◽  
Dump Truck ◽  
Mining Operations ◽  
Production Factors ◽  
Aluminum Smelters

The paper presents the results of hygienic assessment of the working environment and work process factors at surface and underground ore mining operations, ferrous metallurgy plants and aluminum production facilities. It has been established that workers are affected by a complex of production factors (dust, toxic substances, noise, vibration, unfavorable micro climate, etc.), the level of which often exceeds the hygienic standards. The workplace conditions of the primary jobs at these enterprises in 60-80% of cases are classified as hazardous, i.e. Class 3 of various hazard degrees. The incidence of occupational diseases remains high, especially in underground mining and at aluminum production plants. The specific features of mining and metallurgical operations and the severity of unfavorable production factors determine the structure of occupational morbidity. Occupational respiratory diseases are most common among workers in the ferrous metallurgy industry and account for 70.3% in total. Vibration-induced pathologies are most frequently diagnosed among excavator, bulldozer and dump truck operators, and account for 52.9% of all the diagnosed occupational diseases. Hearing organ pathology in the form of neurosensory loss of hearing among workers of mining and metallurgical enterprises ranges from 10.2% (aluminum smelters) to 22.7% (ferrous metallurgy plants) in the occupational morbidity structure. Chronic intoxication with fluorine compounds at aluminum smelters was diagnosed in 68.1% of cases. The results obtained confirm the pressing need to improve the working conditions, introduce preventive measures based on the primary prevention principles, and reduce the risk factors of health problems among the workers.

Analysis on the Steady-state Performance and Losses of a Bent-axis Type Hydraulic Motor Used in Heavy Earth Moving Machinery

2021 ◽  
Author(s):  
Ajit Kumar Pandey ◽  
Amit Kumar ◽  
Nitish Kumar
Keyword(s):  
Steady State ◽  
Electric Motor ◽  
Underground Mining ◽  
Operating Conditions ◽  
Constant Speed ◽  
Working Environment ◽  
Variable Load ◽  
Mining Equipment ◽  
Mining Operations ◽  
Design Guideline

Hydraulic components play a significant role in the mining and construction equipment. It is responsible for smooth change in the output speed, torque, and power of the machine. The hydrostatic drive powered by a constant speed electric motor is widely used in the propel system of the mining equipment. Regulation of the displacements of the pump and the hydro-motor of the drive facilitates the control of the straight running and steering of the machines. In the present scenario, better efficiency and ease of control are the critical aspects to be considered in the design and selection of the hydraulic pump and motor used in underground mining operations. The bent axis hydro-motor is one such equipment that is an electro-hydraulic component that can work in an adverse working environment. The present study deals with the performance analysis of fixed displacement bent axis hydro-motor at different operating parameters such as different temperatures, sizes, viscosity at different loads, and drive speed. For analysis, the hydraulic drive consists of a variable displacement pump rotated by a constant speed electric motor and a fixed displacement hydro-motor. The regulation of the pump displacement controls the speed of the drive. Manually controlled hydrostatic drive propels the said machine against variable load demands. The present work investigates the performances of the hydro-motor used in the mining and construction machine through detailed modeling and experimentations. The steady-state performances are analyzed in terms of slip, torque losses and efficiency of the hydro-motor. The study finds the design guideline to operate the hydrostatic drive using such motors in a reasonable efficiency zone. The model is validated for various operating conditions of the equipment by comparing the predicted results with the test results. The outcome of the present work will be expedient for the preliminary design and assortment of similar hydraulic component used in the mobile, mining equipment.

Life Cycle Assessment of opencast lignite mining

2020 ◽  
Author(s):  
Lukasz Lelek ◽  
Joanna Kulczycka
Keyword(s):  
Life Cycle ◽  
Production Efficiency ◽  
Underground Mining ◽  
Hot Spot ◽  
Electricity Consumption ◽  
Calorific Value ◽  
High Sensitivity ◽  
Cycle Phase ◽  
Mining Operations ◽  
Lignite Mining

Abstract The life cycle phase of fossil fuel extraction is mainly considered in the LCA when evaluating the energy production processes. It is then only one of many unit processes, which contribute to the blurring of mining-relevant results. There are few items in the literature focusing exclusively on the lignite mining phase and analysing the specific mining conditions and associated environmental impacts. The article focuses on the LCA of lignite mining pro-cesses on the basis of data coming from a Polish mine. The technology for opencast lignite mining is noted for its high production efficiency, high level of recovery and lower risk as regards the safety of workers when compared with underground mining systems. However, the need to remove large amounts of overburden to uncover the deposit contributes to a much greater degradation of the landscape. Analysing the results obtained, several key (hot spot) elements of the lignite mining operations were distinguished for modelling the environmental impact, i.e.: calorific value, the amount of electricity consumption, the manner in which waste and overburden are managed. As a result there is a high sensitivity of the final indicator to changes in these impacts.

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