| With the normalization of deep mining of coal resources,the problem of high temperature and heat damage in China’s mines has become more and more prominent,which has seriously threatened the safe production of mines and the physical and mental health of miners.In the face of increasingly severe heat damage prevention and control,China’s existing cooling methods have obvious deficiencies,which are difficult to meet the actual needs of the project.In order to solve the above problems,this paper proposes to use the full air volume cooling technology to cool and dehumidify the air and send it to the well,and the temperature and humidity of the air are further adjusted by using the surrounding rock heating circle of the well and alley,so as to achieve effective treatment of high temperature and heat damage.However,due to the long ventilation route of the working face,the wind temperature rises due to the high temperature surrounding rock and the wind flow of the high temperature surrounding rock,which has a greater impact on the cooling effect.Therefore,in order to rationally use the full air volume cooling technology,it is particularly important to grasp the distribution of the surrounding rock temperature field and the heat regulation ability.This paper adopts the method of combining theoretical analysis,numerical simulation and field measurement,and the main work and conclusions are as follows:(1)Using FLUENT software,the changes of the temperature field distribution and the radius of the heat regulating ring under the action of different ventilation time,inlet wind temperature,inlet wind speed and rock mass temperature conductivity were simulated and analyzed.The results show that the longer the ventilation time,the slower the temperature rise rate of the surrounding rock,and the larger the radius of the thermostat.The lower the inlet wind temperature,the slower the rise rate of the surrounding rock temperature,and the larger the radius of the thermoregulation circle;The larger the temperature conductivity,the faster the temperature change in the surrounding rock,and the larger the radius of the thermostat;The change of inlet wind speed has little effect on the temperature field distribution and the radius of the heat regulating ring,while the change of ventilation time,inlet wind temperature and temperature conductivity has a greater impact on the temperature field distribution,and the isotherm shape of the temperature field of the heat regulating ring can be approximated as a set of symmetrically distributed concentric circle curves,close to the roadway wall area,the heat regulating ring isotherm is dense,the temperature gradient is large,far from the wall area,the temperature gradient is small.(2)Using orthogonal test,taking the radius of the heat regulating ring as the investigation index,and taking the ventilation time,inlet wind temperature,inlet wind speed and rock mass temperature conduction coefficient as the influencing factors,the degree of influence of each factor on the radius of the heating ring was obtained.The results show that the influence of each factor on the radius of the heat regulating ring is the ventilation time> the temperature conductivity coefficient of the rock mass> the inlet wind temperature > the inlet wind speed.(3)The automatic temperature and humidity monitoring system is adopted to monitor the wind temperature at the wellhead of the surface and different positions underground of the Jisan Mine.The results show that the surface temperature changes periodically,so that the wind temperature on the mine air intake route also changes periodically,but in time,the change of underground wind temperature lags slightly behind the change of surface wind temperature,and with the increase of distance from the wellhead,the influence of surface wind temperature on the underground wind temperature gradually decreases.(4)Through on-site measurement,the air thermal parameters of each measurement point on the ventilation route of the 11503 working face of Zhujixi Mine were determined,and the heat gain and loss of each section of the roadway was calculated;On this basis,according to the reverse calculation method of cooling load,the temperature and humidity of the inlet air at the wellhead were predicted by dividing the unit segments,and the cooling load required for mine cooling was calculated based on the prediction results.The results show that the underground heat source is mainly concentrated in the working face area of Zhujixi Mine 11503,and the heat regulating ring and wind flow in the transportation alley area are approximately heat balanced,the air enthalpy value of some roadway sections is reduced,and the surrounding rock heat regulating ring plays a regulating role.In order to make the temperature of the inlet air flow of the 11503 working face meet the requirements of the "Coal Safety Regulations" after the mine adopts cooling measures,that is,the wind temperature T=26°C and the relative humidity takes ψ=85%,then the temperature and humidity of the inlet air at the wellhead of the mine surface need to meet T=20°C,ψ=87%;It is calculated that the cooling load required for mine cooling is 15972 k W,of which the cooling load required for the auxiliary shaft is 7400 k W,the cooling load required for the main shaft is 4875 k W,and the cooling load required for gangue well is 3697 k W.(5)When using the wellhead full air volume cooling system,considering the air leakage phenomenon of a certain air volume in the wellhead room,theoretical analysis and FLUENT software simulation analysis are used to verify the correctness and feasibility of using the system for cooling under the condition of air leakage.The results show that under the premise that the air leakage volume in the wellhead room does not exceed 10%,the wellhead full air volume cooling system can be used to treat the air,and the thermal parameters of the mixed air can meet the parameter requirements of the wellhead inlet air and achieve the expected cooling effect. |
PDF Full Text Request