离子液体对不粘煤煤粉自燃特性的影响

Effect of ionic liquid on the spontaneous combustion characteristics of noncaking pulverized coal

  • 摘要: 为了研究煤粉储运过程中堆积煤粉在漏风环境下氧化升温导致其氧化自燃特征,揭示BMIMBF4离子液体抑制煤粉氧化阻燃反应机制。本文选用高效阻化剂BMIMBF4离子液体对红柳煤矿(HL)不粘煤煤粉进行阻化处理,通过煤粉恒温氧化实验测定5%、10%、15%质量分数的BMIMBF4处理煤粉的自燃临界参数,即煤粉临界自燃温度Tm和着火延迟时间ti,分析BMIMBF4对煤粉加热、自热反应的影响;测试同一高温环境下(各煤粉均被点燃)BMIMBF4对煤粉的宏观阻化特性;通过FT-IR实验表征BMIMBF4对煤粉的微观阻化特征,验证煤粉自燃临界参数变化规律。结果表明:BMIMBF4能够抑制煤粉自热反应并提高煤粉Tmti值,降低煤粉自燃危险性,且其质量分数越大,煤粉自燃临界参数越大,其中15%质量分数的BMIMBF4处理煤粉的Tm为156 ℃,较原煤粉冗余度提高+26 ℃,ti为80 min,较原煤粉着火延迟32 min。在同一环境温度Ta下(Ta>Tm),BMIMBF4处理煤粉的中心点温度、耗氧速率、CO产生量均小于原煤粉,且BMIMBF4的阻化效果随质量分数的增大而增大。BMIMBF4的阻化作用体现在强电负性氟原子与煤中羟基氢原子形成较强的氢键,溶解破坏煤中羟基基团,阻断煤氧链式反应。

     

    Abstract: To study the oxidation behavior induced by the spontaneous combustion of accumulated pulverized coal during its storage and transportation within an air leakage circumstance during increased oxidation and temperature and to reveal the mechanism of BMIMBF4 ionic liquid inhibiting oxidation and flame retardant characteristics of pulverized coal, this paper used a high-efficiency inhibitor BMIMBF4 ionic liquid to inhibit the noncaking coal pulverized coal of the Hongliu coal mine (HL), measuring the critical parameters (critical spontaneous combustion temperature, Tm, and ignition delay time, ti) of pulverized coal spontaneous combustion treated using BMIMBF4 at 5%, 10%, and 15% mass fraction. This work also analyzed the influence of BMIMBF4 on the heating and self-heating of the pulverized coal. Macroscopic resistance characteristics of BMIMBF4 to the pulverized coal were tested under the same high-temperature circumstance (all pulverized coals were ignited). Furthermore, an Fourier transform infrared experiment was used to characterize the microscopic resistance characteristics of the pulverized coal by BMIMBF4 to verify the variation of the critical parameters during pulverized coal spontaneous combustion. Results show that BMIMBF4 can efficiently inhibit the self-heating reaction of the pulverized coal, increase the Tm and ti values of the pulverized coal, and reduce the risk of pulverized coal spontaneous combustion. Moreover, a higher BMIMBF4 mass fraction results in a greater critical parameter of pulverized coal spontaneous combustion. Among them, the Tm of the coal powder treated by BMIMBF4 at a 15% mass fraction is 156 ℃, which is +26 ℃ longer than the original pulverized coal redundancy, and the ti is 80 min, which is 32 min later than the original pulverized coal ignition. Under a similar experimental temperature, Ta (Ta>Tm), the center point temperature, oxygen consumption rate, and CO production of pulverized coal treated by BMIMBF4 are all lower than those of the original pulverized coal, and the inhibition effect is enhanced with the increase in the mass fraction of BMIMBF4. Meanwhile, the inhibited effect of BMIMBF4 is reflected in the strong electronegative fluorine atoms forming strong hydrogen bonds with the hydroxyl hydrogen atoms in coal, dissolving and destroying the hydroxyl groups in the coal and blocking the coal oxygen chain reaction.

     

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