Experimental Study On Pyrolysis And Gasification Of Lignite At High Temperature

With the increasing depth of coal mining in China,the risk of coal and gas outburst increases,become a serious natural disaster in the process of coal mining.At present,the understanding of the mechanism of coal and gas outburst is still in the stage of hypothesis,although the domestic and foreign scholars have carried out a large number of coal and gas outburst simulation experiments,but ignored the evolution of gas outburst coal and preparation process.This experiment designs a set of coal spontaneous combustion simulation experiment device,The device can effectively guarantee the sealing effect of the experimental coal sample at high temperature for a long time.In this paper,the medium and low metamorphic lignite in the closed experimental device is heated for a long time,to improve the gas production,come into being coal and gas mixture with outstanding potential.By means of statistical experimental data and theoretical analysis,the process of coal production in the process of high temperature metamorphism and gas production,and whether the destruction of coal structure caused by gas production can be ejectedThe researches show that:?1?Under different temperature conditions,the same quality of the experimental coal samples in the process of high temperature heating and gas production in the process of producing a large difference,The higher temperature?350??400??is about 8 times bigger than that in the lower temperature?200??250??;?2?The main components of pyrolysis gas is CH₄ and CO₂ in the metamorphic thermal simulation experiments.The volume fraction of them basically accounted for more than80%;?3?The average pressure rate of the spontaneous formation of coal in the reactor in a certain period of time,and the change curve of the final stable pressure with different experimental temperatures are obtained;?4?At the end of the experiment,the coal body looks like foam,the expansion degree is high,the luster is dim,the original structure disappears to a certain extent,the strength of the hand test is low,and the metamorphic degree is deepened.Based on the above results,we can draw the following conclusions:?1?With the increase of temperature,the amount of CO₂ gas increase and then decreased and the amount of CH₄ gas gradually increased,CO₂ gas is mainly generated at lower temperature stage?<350??and CH₄ gas is mainly generated at higher temperature stage??350??.With the increase of temperature and the continuous experiment,CO₂gas and CH₄ showed a rising trend.?2?Gas production increased with the increase of temperature,the influence of gas production on coal outburst characteristics can be classified into two aspects:One is to provide sufficient gas cource,the two is to destroy the coal body.At the same time,the physical and chemical properties of coal are strongly damaged,which results in the increase of coal and gas outburst risk.