煤巷高冒区破碎煤体自然发火微循环理论分析

A Theoretical Analysis of Spontaneous Combustion Micro-circulation in Loose Coal at the Top-Coal Caving Region of a Coal Drift

为了有效防治煤巷高冒区的自燃火灾,通过对高冒区现场试验的测温、取样化验分析和计算机流场模拟,分析了高冒区附近的风流微循环过程,建立了高冒区破碎煤体中的微循环流场和温度场的数值模拟模型.结果表明:高冒区附近的破碎煤体自燃分为高冒区中部的最有可能自然发火区Ⅰ、周边的可能自然发火区Ⅱ和自燃氧化影响区Ⅲ.煤巷高冒区破碎煤体的自燃氧化微循环机理可以表达为氧化耗氧与漏风供氧的氧平衡和氧化生热与漏风对流散热的热平衡,如果漏风供氧能够保证煤炭自燃氧化的进行,同时氧化生热大于散热,则煤炭自燃微循环过程则能持续下去,发展为自燃,有效的高冒区自燃火灾防灭火措施为充填、堵漏和惰化高冒区,破坏氧热微循环过程的进行.

Micro-circulation at the top of a coal caving region was studied by in-situ temperature measurements, sampling, laboratory analysis and numerical simulation. Models of the flow and temperature fields show that broken coals near the top of the caving region can be divided intothree zones. These are. A zone most likely to see spontaneous combustion,Ⅰ ; A zone where spontaneous combustion is possible,Ⅱ , and; A zone affected by spontaneous combustion, Ⅲ. The mechanism of spontaneous combustion involves a balance of oxygen supply, from leakage, and consumption by oxidation. Heat flows also balance, heat flowing from the area to cooler zones while being produced locally by the oxidation process. Self-ignition occurs if leakage oxygen and heat production occur to a sufficiently great extent. Effective fire prevention can be seen to entail filling, plugging and interting at the top of the coal caving region.