Study On Thermophysical Properties Measurement And Temperature Field Distribution Of Loose Coal Bulk

The current situation of coal production in our country allows for no optimism, it shows according to statistics that 50% of coal mines have spontaneous combustion hazard seam, the spontaneous combustion broken ratios of key state-owned coal mine can arrive at 0.2 times per Mt, and it is worse with the local coal mines. One of the important reasons is that the source of coal spontaneous combustion can not located rapidly and accurately, which leads to a great loss.Accoding to the status that the thermophysical parameters of loose coal needed for the location of coal spontaneous combustion heat source is difficult to be measured accurately and distribution of temperature field in loose coal and its influencing factors are not yet intensively researched, the measuring method and measuring system of loose coal thermophysical parameters and distribution of temperature field in loose coal and its influencing factors are studied, which offer foundation for accurate locating of coal spontaneous combustion heat source.Based on comprehensive research and analysis of existing measuring method and measuring system, a new method of measuring thermal conductivity,thermal diffusivity and thermal capacity for loose coal is put forward, an intelligent loose coal thermophysical properties measuring system is designed and built, and then change of loose coal thermophysical parameters with temperature, water content, voidage is studied. Based on theoretical investigation of loose coal temperature field, experimental coal stockpile(4×2.4×1.5m) is built on the ground, the distribution and influencing factors of temperature field is studied by artificial heat source(50℃～350℃).The debugging and practical application of the measuring system show that the auto-controling temperature, auto-data acqusiting, auto-judging data's validity, and auto-processing data are realized.Repeating precision of measurement results for loose coal thermophysical parameters is less than 1%. Distribution of temperature field at different distance and at different time with temperature of heat source from 50℃to 350℃is simulated, which offer foundation for the locating technology of coal spontaneous combustion heat source by the temperature method. Based on the theory of heat transfer, mathematical model of loose coal temperature field is built, through which the calculating results of temperature field are in accordance with experimental data and parameter estimating results of loose coal thermophysical are in line with measurement results.