Study on Adiabatic Oxidation Characters of Coal with Applying a Constant Temperature Difference To Guide the Oxidation of Coal with Temperature Rising

It is of great importance to understand the adiabatic oxidation and heating process of coal as well as its graphic expression when studying the characteristics and parameters of the spontaneous combustion of coal. This study is to focus on the characteristics of the low-temperature oxidation of coal and its macroscopic manifestation. However, the adiabatic oxidation method that is widely adopted nowadays is just to provide an approximate heat insulation environment (usually by temperature-tracking arithmetic), which would create difficulty in either conducting experiments or providing an accurate description of the process and characteristics of the spontaneous combustion of coal as a result of the susceptible nature of the very small amount of heat released by the oxidation of coal. In this paper, a new method of applying a constant temperature difference to guide the oxidation of coal is introduced, which is capable of providing a coal sample with over temperature protection as well as helping researchers obtain adiabatic oxidation curves (time–temperature curves) of coal by proper experimental design and calculation. Therefore, by analysis of the adiabatic oxidation process, the study of characteristics and mechanisms of the low-temperature oxidation and spontaneous combustion of coal can be achieved, thus providing a reliable and innovative testing method for the fundamental research on the spontaneous combustion of coal. Meanwhile, in this paper, four types of coal samples were tested by the new method and their adiabatic oxidation curves were also drawn and studied by theoretical analysis and calculations. On the basis of the adiabatic oxidation curves, this paper provides the calculation results for the heat generation rate and spontaneous combustion period for the low-temperature oxidation of coal in the adiabatic environment. At last, on the basis of these experiments, analyses, and calculations, this paper also compares the results of a constant temperature difference to guide the oxidation method of coal with a traditional adiabatic oxidation method, which shows that the new method has more advantages, such as a low initial temperature, the usage of air rather than oxygen to oxidize coal, a shorter test duration, and a very high test success rate.