煤层气浓缩分离工艺的研究

发布时间：2018-05-19 21:34

本文选题：煤层气 + 浓缩　；参考：《西安科技大学》2017年硕士论文

【摘要】：煤层气在国内外化工生产、发电和燃料方面都具有不可替代的使用价值。但目前大部分低浓度煤层气资源并未被完全利用,主要是因为煤层气组分中含有很多不可燃组分N2。甲烷和氮气分子动力学直径比较接近,很难将其分开,因此将甲烷和氮气的有效分离是浓缩甲烷的关键技术,这也是解决低浓度煤层气排空需要我们迫切解决的问题。目前未达到30%煤层气通常被直接排放到大气中,造成严重的环境污染和资源浪费,针对上述存在的现状,本论文首次通过溶剂吸收的方法来浓缩煤层气中的甲烷,具体的研究内容包括:(1)溶剂的选择,针对某矿井煤层气中各个组分(主要是氮气和甲烷)的特点,从吸收甲烷的角度选择并模拟计算的溶剂有:CC14、四乙氧基硅烷(TEOS)、四甲基硅烷(TMS)、十四酸异丙酯(IPM)、碳酸丙烯酯(PC)、聚乙二醇二甲醚(DEPG)3,3-二甲基戊烷,从吸收氮气的角度选择并模拟的溶剂有:N,N-二甲基酰胺(DMF)和N-甲基吡咯酮(NMP),在相同的条件下分析了各种溶剂的物性参数,包括密度、传热系数、粘度、饱和蒸汽压、表面张力等参数,此外还计算了各种溶剂对煤层气组分的溶解度,并做了溶解度曲线对比。(2)从含氧和不含氧煤层气两个角度研究低煤层气浓缩工艺,使用CC14溶剂对含氧煤层气的吸收工艺进行建模,结果将甲烷的体积分数从30%浓缩到91.5%,回收率为85%,达到国家二级天然气使用指标,可作为基本的化工原料;将甲烷体积分数为5%煤层气浓缩到34%,回收率73.4%,达到国家三级煤层气使用指标,这类浓度的煤层气可用于工业及民用发电,生活燃料。使用DEPG溶剂对甲烷浓度为25.3%的无氧煤层气进行稳态建模,结果可以将甲烷的体积分数从25.3%浓缩到70%,回收率为高达83%,吸收过程的液气比在1.0左右,效果可观。(3)对甲烷浓度为25.3%的煤层气吸收工艺采用速率型建模,并对比速率型模型和平衡型模型的区别,误差在3%以内,模拟结果可作为煤层气吸收工艺工业化的理论支撑,此外还计算了设备参数(塔径、塔板数、板间距、溢流堰高度、塔板类型),最后对工艺中的影响因素进行调优和分析。
[Abstract]:Coalbed methane has irreplaceable value in chemical production, power generation and fuel production at home and abroad. However, most of the low concentration CBM resources have not been fully utilized, mainly because there are many non-combustible components N _ 2 in the coal-bed methane components. The molecular dynamics of methane and nitrogen are similar in diameter, so it is very difficult to separate methane from nitrogen. Therefore, the effective separation of methane and nitrogen is the key technology of methane concentration, which is also an urgent problem that we need to solve in order to solve the problem of coal bed methane emptying with low concentration. At present, coal bed methane (CBM) which is not up to 30% is usually discharged directly into the atmosphere, which causes serious environmental pollution and waste of resources. In view of the above existing situation, this paper firstly concentrates methane in CBM by solvent absorption method. The specific contents of the study include the selection of solvents, aiming at the characteristics of various components (mainly nitrogen and methane) in coalbed methane in a mine. The solvents selected and simulated from the angle of methane absorption are: CC14, Tetraethoxysilane, Tetramethylsilane, Isopropyl Tetradecanoate (IPMN), Propylene Carbonate (PCO), Polyethylene Glycol dimethyl Ether (DEPGN), 3-Dimethylpentane. The solvents selected and simulated from the point of view of nitrogen absorption are: (1) N (N) -dimethyl amide (DMF) and N- (methylpyrrolidone) (NMP). Under the same conditions, the physical properties of various solvents, including density, heat transfer coefficient, viscosity, saturated vapor pressure, are analyzed. Surface tension and other parameters, in addition, the solubility of various solvents to the components of coal-bed methane is calculated, and the solubility curve is compared. The absorption process of oxygen-containing coalbed methane was modeled by using CC14 solvent. The results showed that the volume fraction of methane was concentrated from 30% to 91.5%, and the recovery rate was 85%, which reached the national secondary natural gas usage index and could be used as a basic chemical raw material. The methane concentration of 5% CBM is condensed to 34%, and the recovery rate is 73.4%. The methane concentration can be used in industrial and civil power generation and domestic fuel. The steady-state model of anaerobic coal-bed methane with 25. 3% methane concentration was established by using DEPG solvent. The volume fraction of methane was condensed from 25. 3% to 70%, the recovery rate was as high as 83%, and the ratio of liquid to gas in the absorption process was about 1. 0. The rate model of methane absorption process with 25. 3% methane concentration is adopted, and the difference between rate model and equilibrium model is compared. The error is less than 3%. The simulation results can be used as theoretical support for industrialization of coal bed methane absorption process. In addition, the equipment parameters (tower diameter, tray number, plate spacing, overflow Weir height, tray type, etc.) were calculated. Finally, the influencing factors in the process were optimized and analyzed.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD845

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