低氧浓度条件下煤中活性基团的低温反应过程及其热效应

The coal oxidation at low temperatures is very important for the development of spontaneous combustion of coal. According to analysis, the oxygen concentration at the zones, where the spontaneous combustion of coal is easy to occur, is usually low. However, there is only few works focusing on the coal reaction and heat effect under the conditions of low oxygen concentration and low temperature. The reactions of active groups in coal will be studied using a in-situ FTIR. The in-situ FTIR is designed based on an ordinary FTIR. A reaction chamber is used to load coal sample; a gas providing system is used to simulate different gas atmospheres, gas flow and gas concentration; an electronical heater is used to simulate different temperature surroundings. Using the in-situ FTIR, the real-time changes of active groups in coal reactions under different conditions can be obtained. The micro heat effect at the beginning of coal oxidation will be studied using C80 calorimeter. The oxygen consumption, products and self-heating during coal spontaneous combustion will be studied using a self-designed comprehensive testing equipment. Based on experimental results, the project will analyze the relationship between the real-time changes of active groups and macro characteristics. The types and reaction sequences of the main active groups in coal, which have obvious effects on the development of spontaneous combustion of coal, will be revealed. A chemical and thermal model of coal reaction under the conditions of low oxygen concentration and low temperature will be established. The mechanism of heat effect at the beginning of spontaneous combustion can be revealed based on chemical reaction of active groups. The project is helpful to modify the theory of spontaneous combustion of coal. The study will provide a basis for the study on a new method to prevent spontaneous combustion through restraining the reaction chain of active groups.

从致灾过程看，低温阶段的煤氧化蓄热是煤自燃能否持续发展的关键；从反应环境看，煤自燃区域多具有氧气浓度低的特点。煤自燃本质上是煤中基团反应的结果，但目前对低氧浓度条件下（O2%≤15%）煤中基团的低温（20-100℃）反应及热效应的针对性研究较少。本项目通过构建红外光谱原位测试系统研究基团在不同氧浓度条件下的实时变化；采用C80微量热技术研究低氧浓度条件下煤低温反应的热效应、活化能等热力学特性；采用煤自燃综合测试装置研究煤低温贫氧反应的耗氧、产物、自热升温等特性。在此基础上，对比分析基团变化和热力学特性的内在联系，阐明影响煤自燃发展的关键活性基团种类及其反应序列，构建低氧浓度条件下煤低温反应的化学热力学模型，从基团反应角度揭示煤自燃初期的产热机理。研究成果有利于完善煤自燃理论体系，并为基于抑制关键活性基团反应链原理的煤自燃防治新技术的研究提供科学依据，从而有效指导煤自燃灾害的防治。

从致灾过程看，低温阶段的煤氧化蓄热是煤自燃能否持续发展的关键；从反应环境看，煤自燃区域多具有氧气浓度低的特点。煤自燃本质上是煤中基团反应的结果，但前期对低氧浓度条件下煤中基团的低温反应及热效应的针对性研究较少。基于这一现状，本项目开展了低氧浓度条件下煤中活性基团反应机理及其热力学特性方面的研究。主要研究成果如下：.（1）揭示了煤中活性基团的分布及其转变规律。测试了不同变质程度煤中活性基团分布情况，并通过构建红外光谱原位测试系统研究了基团在不同氧浓度条件下的实时变化规律，推导了主要活性基团的转换过程。.（2）阐明了低氧浓度条件下煤中活性基团反应过程的产热产物特性。采用C80微量热技术研究了低氧浓度条件下煤低温反应的热效应、活化能等热力学特性；采用煤自燃综合测试装置研究了煤低温贫氧反应的耗氧、产物、自热升温等特性。.（3）明确了氧气浓度对煤中活性基团反应过程的影响机制。揭示了低氧浓度条件下煤氧化自燃过程特性及其着火机制，确定了煤自燃发生的极限氧气浓度；基于分子动力学模拟方法再现了低氧浓度条件下活性基团的转换过程，从分子层面揭示了低氧浓度导致煤氧化自燃特性差异的机理；为进一步认识低氧条件下的煤自燃发生、发展规律及其高效治理提供了理论基础。.（4）构建了低氧浓度条件下煤中活性基团的反应模型。对比分析了基团变化和热力学特性的内在联系，并基于理论分析、实验测试和量子化学计算等综合手段，阐明了影响煤自燃发展的关键活性基团种类及其反应序列，构建了低氧浓度条件下煤低温反应的化学热力学模型，从基团反应角度揭示了煤自燃初期的产热机理。.（5）研制了可有效抑制煤中关键活性基团反应的高效化学阻化剂。在阐明影响煤自燃发展的关键活性基团的基础上，研发出了抑制相关反应过程的高效化学阻化剂，通过抑制或阻断煤中关键活性基团的反应序列，实现煤自燃灾害的有效防治。.研究成果发表高水平学术论文17篇（均为SCI或EI检索），其中第一作者10篇（SCI检索8篇、EI检索2篇）；出版专著1部；获授权国家发明专利1项；获计算机软件著作权1项。课题组成员中3人新晋升副教授、2人博士毕业、3人硕士毕业。.本项目研究成果从微观上揭示了煤低温氧化阶段的自热升温机理，并为基于抑制关键活性基团反应的煤自燃防治新技术研究提供了科学依据和技术基础，能有效地指导煤自燃灾害的防治。