| The low temperature oxidation of coal is a serious threat to the safety of coal storage and transportation,at the same time,it brings great economic losses to the coal industry.At present,China's power industry is still dominated by thermal power generation.It is necessary to effectively prevent and control the low-temperature oxidation of coal,study the low-temperature oxidation characteristics of coal,and determine the temperature rise change of low-temperature oxidation of coal.According to the actual situation of coal used in power plant,taking Indonesian coal as the research object,this paper establishes a set of theoretical methods and related experimental systems for testing the main parameters in the process of low-temperature oxidation,carries out the thermobalance test,constant temperature oxidation test,temperature rise oxidation test and field coal pile test,and obtains some useful indexes.Firstly,the coal quality characteristics of three kinds of coal were analyzed.The C/O ratios of three kinds of coal were: Indonesia coal(36.00)> Australia Mongolia coal(18.74)> Australia coal(14.3).The oxidation tendency was preliminarily determined.On the basis of element analysis,through the study of combustion characteristics,it was shown that Indonesia coal ignition and reaction speed were faster than high volatile bituminous coal,and compared with Australia Mongolia coal and Australia coal The results show that the decomposition temperature of three kinds of coal is Indonesia coal(185.06 ?)<Australia Mongolia coal(274.02?)< Australia Mongolia coal(290.81?),and the ignition point temperature is Indonesia coal(284.92?)< Australia Mongolia coal(395.12 ?)<Australia coal(422.22?),which reveals the positive correlation between oxygen content and oxidation intensity,Moreover,Indonesian coal is more easily decomposed and oxidized by heat.Then the constant temperature oxidation test-bed of coal pile is established.The change of calorific value of coal is studied by simulating the oxidation temperature field of coal.The results show that the calorific value of coal decreases obviously at 105?.At the same time,the temperature rise test-bed of coal stack is established to study the oxidation temperature rise of coal by simulating the oxidation temperature field of coal.The resultsshow that Indonesian coal is a very dangerous coal type.When the heat storage temperature reaches 105 ?,the internal oxidation begins to accelerate.When the heat storage temperature reaches 120?,the internal oxidation becomes very fierce and the risk increases.Australian and Mongolian coal is a relatively dangerous coal type,and its stack is very dangerous The oxidation of the deposition process has the trend of periodic cycle development,that is,the temperature of oxidation heat accumulation accelerates the internal oxidation to the critical temperature After the oxidation heat storage reaches the first accelerated oxidation temperature of 105?,there is a process of accelerated oxidation,but when it reaches the critical temperature of 130?,the oxidation starts to slow down until it reaches the second accelerated oxidation temperature of 175?;Australian coal belongs to relatively stable coal,and its accumulation process is basically safe.Finally,according to the results of the previous study,the field test was carried out to determine the height of the oxidation area and the depth of the oxidation point of Indonesian coal,that is,the height to height area of the coal pile(i.e.the 2m-6m height layer of the coal pile)is the high-speed area of coal oxidation,which is perpendicular to the coal pile At the same time,the characteristic temperature of the oxidation heat storage at a severe oxidation point inside the Indonesian coal pile is obtained,that is,when the temperature reaches about87 ?,the internal oxidation heat storage of the coal and the heat dissipation to the outside gradually tend to balance,which is consistent with the results of the basic research in the laboratory. |
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