Application of HEMS cooling technology in deep mine heat hazard control

This paper mainly deals with the present situation, characteristics, and countermeasures of cooling in deep mines.Given existing problems in coal mines, a HEMS cooling technology is proposed and has been successfully applied in some mines.Because of long-term exploitation, shallow buried coal seams have become exhausted and most coal mines have had to exploit deep buried coal seams.With the increase in mining depth, the temperature of the surrounding rock also increases, resulting in ever increasing risks of heat hazard during mining operations.At present, coal mines in China can be divided into three groups, i.e., normal temperature mines, middle-to-high temperature mines and high temperature mines, based on our investigation into high temperature coal mines in four provinces and on in-situ studies of several typical mines.The principle of HEMS is to extract cold energy from mine water inrush.Based on the characteristics of strata temperature field and on differences in the amounts of mine water inrush in the Xuzhou mining area, we proposed three models for controlling heat hazard in deep mines:1) the Jiahe model with a moderate source of cold energy;2) the Sanhejian model with a shortage of source of cold energy and a geothermal anomaly and 3) the Zhangshuanglou model with plenty of source of cold energy.The cooling process of HEMS applied in deep coal mine are as follows:1) extract cold energy from mine water inrush to cool working faces;2) use the heat extracted by HEMS to supply heat to buildings and bath water to replace the use of a boiler, a useful energy saving and environmental protection measure.HEMS has been applied in the Jiahe and Sanhejian coal mines in Xuzhou, which enabled the temperature and humidity at the working faces to be well controlled.

Progress of heat-hazard treatment in deep mines

Based on the urgency of thermal hazard control in deep coal mines,we studied the status of deep thermal damage and cooling technology both at home and abroad,summarized the causes of deep thermal hazard,analysed and compared the control technologies for deep thermal hazards.The results show that the causes of deep thermal damage can be attributed to three aspects,i.e.,climate,geological and mining factors,of which the geological factors are deemed the major reasons for thermal hazards.As well,we compared a number of cooling technologies of domestic and overseas provenance,such as central air conditioning cooling technology,ice cooling technology and water cooling technology,with one other cooling technology,i.e.,the HEMS cooling technology,which has a large and important effect with its unique＂pure air＂cooling technology,realizes the utilizing of heat resources from underground to the ground.This technology makes use of heat obtained underground;thus the technology can promote low-carbon environmental economic development in coal mines,in order to achieve low- carbon coal production in China.

Principles and technology for stepwise utilization of resources for mitigating deep mine heat hazards

As is well known, deep mines are hot. As mining depth increases, the temperature of the surrounding rock also increases. This seriously affects mine safety and production and has restricted the exploitation of deep coal resources. Therefore, reducing the working face temperature to improve working conditions by controlling these heat hazards is an urgent problem. Considering problems in cooling deep mines both domestically and abroad along with the actual conditions of the Zhangshuanglou coal mine, we propose a HEMS technology that uses heat resources from deep mines in a stepwise manner. HEMS means a high temperature ex-change machinery system. Mine inrush-water is used as a source of cooling. Twice the energy is extracted from the mine inrush water. Heat is used for building heating in the winter and cold water is used for cooling buildings in the summer. This opens a new technology for stepwise utilization of heat energy in deep mines. Energy conservation and reduced pollution, an improved environment and sustainable economic development are realized by this technique. The economic and social effects are obvious and illustrate a good prospect for the application and extension of the method.

Geological factors controlling deep geothermal anomalies in the Qianjiaying Mine,China

Here,the geological factors controlling deep geothermal anomalies in mines were studied based on the geotemperature,lithologic thermal conductivity,and related geological data collected from the Qianjiaying Mine,China.A simulation of the change in magma waste heat,conducted using the ANSYS Workbench,revealed the distribution characteristics of geothermal anomalies in this mine and the corresponding geological control factors.The results revealed the following points.(1)First-degree heat hazard level(temperature=31-37℃)occurred in the central and southwestern parts of the mine at an^600-m depth,while second-degree heat hazard level(temperature≥37℃)occurred at an^800-m depth.The geotemperature and geothermal gradient in the southwestern part of the mine were anomalously high.(2)The geotemperatures measured in the mine generally reflected a standard increase with depth,while the geothermal gradient remained unchanged with depth.The geothermal gradient and its average value in the study area were 0.70-4.23 and 2.12C·hm^-1,respectively.(3)A combination of stratum characteristics,geological structure,and groundwater characteristics led to geothermal anomalies in mines;additionally,the waste heat from magma had no significant effect on the geothermal field.

Unsteady temperature field of surrounding rock mass in high geothermal roadway during mechanical ventilation

To explore the spatial-temporal evolution law of rock mass temperature in high geothermal roadway during mechar^ical ventilation, a series of experiments were conducted based on the physical simulation test system of thermal and humid environment in high geothermal roadway, which is a method independently developed by China University of Mining and Technology. The results indicate that during ventilation, the disturbed region of the temperature extends gradually from shallow area to deep area in the surrounding rock mass of the roadway. Meanwhile, the temperature increases as the exponential function from shallow area to deep, with steady decrease of the temperature gradient and heat flux. As the ventilation proceeds, the relationship between dimensionless temperature and dimensionless time approximately meets Hill function.