含水率对油气伴生煤恒温热解后氧化特性的影响

Influence of water content on the oxidizing properties of oil and gas associated coal after thermostatic pyrolysis

为了揭示不同含水率油气伴生煤样经恒温热解后氧化特性的演变规律,采用程序升温试验,确定煤样的特征温度与干裂温度点,从宏观角度分析经恒温热解处理后不同含水率煤样氧化过程中气体产物、气体产生率、耗氧速率及放热强度的变化情况,分段计算了氧化反应A(30~70℃)、B(70~110℃)、C(110~170℃)3个阶段的表观活化能值。结果表明:原煤氧化升温过程中临界温度在70℃左右,干裂温度在110℃左右;不同含水率煤样氧化过程中,耗氧速率与放热强度在110℃之前上升速率较为缓慢,110℃之后急剧增加,并且原煤的耗氧速率、放热强度均大于高含水率煤样;氧化反应A阶段经热解处理后水分对煤样氧化反应起促进作用,氧化反应B阶段不同含水率煤样表观活化能值差异性较小;氧化反应C阶段随着含水率的升高,15%、20%含水率对煤自燃起抑制作用,高含水率煤样自燃倾向性低。研究结果对油气伴生煤自燃火灾防治有一定的指导意义。

In order to reveal the evolution rule of oxidation characteristics of coal samples with different water content of oil and gas accompanied by constant temperature pyrolysis,the programmed heating test was used to determine the characteristic temperature and dry cracking temperature point of the coal samples,analyzing the gas generation rate,oxygen consumption rate,and exothermic intensity during the oxidation process of coal samples with varying water content after constant-temperature pyrolysis treatment from a macroscopic perspective.The apparent activation energy values of three stages of the oxidation reaction,namely,A(30~70℃),B(70~110℃),and C(110~170℃),were calculated in sections.The results show that the critical temperature of raw coal oxidation heating process is around 70℃,and the dry cracking temperature is around 110℃;During the oxidation process of coal samples with different water contents,the oxygen consumption rate and exothermic intensity increase slowly before 110℃,and sharply after 110℃.Moreover,the oxygen consumption rate and heat release intensity of raw coal are greater than those of high water coal samples;The water content after pyrolysis treatment in stage A of the oxidation reaction promotes the oxidation reaction of coal samples,while in stage B of the oxidation reaction,the difference in apparent activation energy values of coal samples with different water contents is relatively small;In stage C of oxidation reaction,as the water content increases,15%and 20%water contents have an inhibitory effect on coal spontaneous combustion,while high water content coal samples have a low tendency for spontaneous combustion.The findings of the study are of guide meaning for the control of spontaneous combustion fires in oil and gas associated coal.