不同挥发分煤尘层最低着火温度变化规律研究

针对煤化工等行业的沉积煤尘热自燃问题,运用煤尘层最低着火温度测试系统,研究了不同挥发分煤尘层的着火状态、不同挥发分及不同厚度煤尘层最低着火温度的变化规律。结果表明:煤尘层厚度为5 mm时,挥发分质量分数大于35%的煤尘在较低温度便出现着火现象,肉眼很容易观察到火星的出现,温度曲线波动剧烈,而对于挥发分质量分数小于15%的煤尘,通过煤尘层内部"温度达到450℃"来判断其着火;在灰分质量分数相当的情况下,煤尘层最低着火温度随挥发分增加呈严格递减的趋势变化;得到了煤尘层厚度和最低着火温度的函数关系式,通过试验得到了挥发分质量分数为37.45%煤尘的重要常数M和N。

Study on the changing regularity of the minimum ignition temperatures of the different volatile coal dust layers

This paper is aimed at making a study on the changing regularity of the minimal ignition temperatures at the different volatile coal dust layers in hoping to identify and determine the thermal self-ignition threshold due to the accumulation of the coal dust in the coal chemical industry and other related industries.For the said study purpose,we have made an investigation of the coal dust layer status-in-situ in the laboratory conditions while different volatiles and the changing regularity of the minimum ignition temperatures of the dust layer with different volatile and different thicknesses by using the minimum ignition temperature of coal dust layer test system.The results of our investigation and tests indicate that,there exists a certain relation between the ignition criteria of the coal dust layer and the volatile content of the said coal dust ignition layer according to the test of the minimal ignition temperature of the dust layer,that is to say,when the dust layer thickness is 5 mm with the volatile content rate being over 35％,there may appear coal dust burning likeliness at low temperatures which is easy to be found by observing the appearance of mars and the temperature curve with the dramatic fluctuation by the naked eyes.However,if the volatile content rate of the coal dust is less than 15％,it can only be determined whether it is likely to lead to the fire risk when the "internal temperature reaches 450 ℃ ".Nevertheless,there may exist some gaps among the states of the fire about the different volatile coal dusts.Under the experiment conditions,if the ash content rate remains constant,the minimal ignition temperature of the coal dust layer tends to change with the increase of the volatile content,indicating a strictly decreasing trend.For example,under the experimental conditions,with the increase of the volatile content rate being from 7.09％ to 37.45％,the minimum ignition temperature of the layer tends to drop from 370 ℃ to 280 ℃.Through a series of testing experiments based on the condition with the volatile content rate being 37.45％,the key constant of No.7# coal dust can be found equal to M and N,which serves as the characteristic feature of the reactants reflecting the physical and chemical properties of the reactants.Thus,the conclusion we have gained in this paper can be expected to provide valuable theoretical basis for effective prevention of the fire risks and the explosion of coal deposit dust layer in the coal chemical industry businesses or companies.