【作者】 王鹏飞；

【导师】 冯涛；

【作者基本信息】 中南大学 ， 安全技术及工程， 2012， 博士

【摘要】 瓦斯是仅次于二氧化碳的重要温室气体,单位质量的瓦斯对大气温室效应的影响相当于同质量二氧化碳的21倍。煤矿乏风是主要的瓦斯工业排放源之一,减排煤矿乏风瓦斯,可以减少温室气体排放。同时,乏风瓦斯的主要成分为甲烷,是优质洁净的气体能源。据统计,目前我国每年通过煤矿乏风排入大气中的瓦斯含量约为200亿m3,如果将此乏风进行减排和利用,相当于2500万吨标准煤,可以减排2.7亿吨当量二氧化碳。因此,合理回收利用煤矿乏风瓦斯具有环保和节能双重意义。煤矿乏风风排量巨大、瓦斯浓度低以及浓度不稳定,这些特点决定了煤矿乏风瓦斯很难利用传统燃烧器在没有辅助燃料的情况下直接进行燃烧。目前,热逆流氧化技术是实现煤矿乏风瓦斯有效减排和热回收利用的主要技术之一。本文通过理论分析、数值模拟及实验相结合,对煤矿乏风低浓度瓦斯热逆流氧化机理和特性开展了系统综合的研究：(1)通过理论分析,建立了燃烧波波速与燃烧区域最高温度的关系式,得到燃烧波波速和燃烧区域最高温度的封闭解；通过与稳态热逆流燃烧器类比,得到了多孔介质中热逆流氧化的简化理论解。(2)通过对蜂窝陶瓷蓄热氧化床流动过程进行理论分析,建立了包含乏风进气速度、蜂窝陶瓷通道直径(或边长)、气体粘度及其氧化床温度场等多参数影响下的三种蜂窝陶瓷氧化床冷热态下的阻力计算数学模型。(3)通过建立煤矿乏风低浓度瓦斯热逆流氧化的一维数学模型,并对Fluent软件进行二次开发,对煤矿乏风低浓度瓦斯热逆流氧化过程进行了数值模拟,考察了包括煤矿乏风进气速度、乏风甲烷浓度、换向半周期、壁面热损失、蜂窝陶瓷比热容及其孔隙率等工况参数对热逆流氧化温度场、甲烷转化率和氧化床阻力的影响。(4)基于自行设计制作的低浓度瓦斯热逆流氧化实验系统,对煤矿乏风低浓度瓦斯热逆流氧化开展了系统的实验研究。实验内容包括乏风甲烷氧化温度、装置散热损失、热启动温度场以及乏风进气速度、甲烷浓度、换向半周期、壁面热损失和蜂窝陶瓷孔隙率对热逆流氧化的影响。(5)采用六铝酸盐作为涂层涂覆在γ-氧化铝表面,再负载贵金属活性组分制作成蜂窝陶瓷整体式催化剂用于煤矿乏风低浓度瓦斯热逆流氧化,并通过单管固定床催化氧化试验对所制备的催化剂进行了表征、活性评价、水热稳定性测试及其抗硫中毒能力测试。(6)对低浓度甲烷气体进行热逆流催化氧化实验研究,对比有无催化剂作用下热逆流反应,实验结果表明催化剂的存在不仅大大降低了乏风中低浓度甲烷氧化温度,而且甲烷转化率得到明显提高,同时也提高装置处理乏风的能力。(7)以单台处理能力为5万m3/h的煤矿乏风氧化装置为研究对象,计算了单台装置每年摧毁甲烷产生的碳减排量及其可利用热量产生热水和蒸汽量,也对单台处理装置每年的CDM收益和能量利用收益进行了评估,并对其投资回报率进行了分析。更多还原

【Abstract】 It is well known that methane is the second largest contributor to global warming after carbon dioxide, and it is21times more potent than carbon dioxide over a100-year timeframe in trapping heat in the atmosphere. The vetilation air methane (VAM) of coal mine is one of the primary industrial methane emission sources. The reduction of VAM will make outstanding contributions for reducing emissions that cause of global warming. Meanwhile, the main components of ventilation gas are methane, which is the high quality undefiled gas energy. According to the statistics, the gas emission to the atmosphere through ventilation air methane is about20billion m3, which is corresponding to25miliiion tons standard coal that can reduce emission270million tons equivalent carbon dioxide. Therefore; recovery and utilization of VAM has great environment protection and energy-saving significance.VAM is the most difficult source of methane to use as an energy source, as the air volume is large and the methane resource is dilute. At present, the thermal flow-reversal reactor is an effectively technology that realize recovery and utilization of VAM. Through theoretical analysis, numerical simulation and experiment, we made comprehensive research on the oxidation mechanism and characteristics of thermal reverse-flow oxidation of VAM:(l)The two relations about combustion wave and the highest combustion area temperature have been established that got the closed solution of combustion wave and combustion area. The simple theoretical solution about porous media thermal flow-reversal oxidation was also obtained.(2)The resistance mathematical model have been established in the cold and hot state of three honeycomb ceramics oxidation bed that influence by VAM intake velocity, honeycomb ceramics channel diameter (side length), gas viscosity and the temperature fields of oxidation bed that through theoretical analysis about the flowing process of the honeycomb ceramics thermal storage oxidation bed.(3)Based on secondary development on FLUENT, a one-dimensional mathematical mode was set up to simulate the thermal structures of the oxidation bed and the effect of operating condition parameters on the thermal structure, oxidation ratio of methane and outlet temperature, which includes flow velocity, methane concentration, half-period, thermal loss, honeycomb ceramics specific heat capacity and porosity.(4)According to the experiment system of VAM thermal flow-reversal oxidation made by self-designed; the comprehensive study to the VAM thermal flow-reversal oxidation hase been developed, which contains heat loss, temperature fields of hot-start, methane concentration, ventilation gas and honeycomb ceramics porosity.(5)Hexa-aluminate as coatings coat the surface of γ-alumina and load active components of noble metal have been used to make the honeycomb ceramics integral catalyst and use it in the VAM low concentration gas thermal flow-reversal oxidation and through single pipe fixed bed catalytic oxidation experiment testing the preparation catalyst about characterization, activity evaluation, thermal stability and sulfur poisoning ability.(6)Through the experiment of thermal flow-reversal catalytic oxidation of VAM, comparing with thermal flow-reversal without catalyst, it concluded that not only did the catalyst decrease the oxidation temperature of VAM, but also the conversation rate of catalyst enhanced obviously, at the same time, the catalyst improve the device’s treatment capacity.(7)Taken the single station device treating50000m3/h VAM as research object, calculated the carbon emission reduction which produced by destroying methane with single station device per year and the quantity of hot water and steam, which were produced by the utilized heat, meanwhile, the CMD income and energy using income of single station device per year were evaluated, also, the rate of return was analyzed.更多还原