煤矿瓦斯真空变压吸附分离与富集的研究

发布时间：2018-05-29 17:27

本文选题：煤矿乏风瓦斯 + 煤矿瓦斯　；参考：《大连理工大学》2014年博士论文

【摘要】：我国是世界上第二大能源消耗国,其中煤炭在能源消费结构中占70%以上,每年因采煤而排放的CH4量超过200亿m3,抽采出的煤矿瓦斯中因混入大量的空气,使得大部分煤矿瓦斯浓度较低不能直接利用,其利用率仅10%。煤矿瓦斯主要成分为CH4,直接放空一方面会污染空气,引起温室效应；另一方面会浪费能源。因此,对于煤矿瓦斯的分离和富集的研究具有十分重要的现实意义和理论价值。煤矿瓦斯主要含有02、N2和CH4。本文针对煤矿乏风瓦斯(0.52%CH4,N2平衡气)、含氧煤矿瓦斯(10-15%O2,30-40%CH4, N2平衡气)和脱氧后煤矿瓦斯(40-50%CH4,N2平衡气)分别进行了分离与富集的初步探讨。由于N2和CH4物理特性较为接近,难以找到合适的吸附剂采用变压吸附工艺(PSA, pressure swing adsorption)对N2和CH4进行有效地分离。本文利用9种商业活性炭、一种活性炭纤维及一种13X分子筛为吸附剂,研究了N2和CH4在不同吸附剂上的吸附热力学和吸附动力学特性。利用上述9种商业活性炭和5种自制炭质吸附剂,考察其CH4/N2分离因子与吸附剂比表面积、微孔孔容、微孔率及微孔孔径分布之间的关系,确定了分离CH4/N2的主要影响因素,为后续活性炭的制备提供指导意义。以椰壳基活性炭为吸附剂,采用真空变压吸附(VPSA, vacuum pressure swing adsorption)工艺对煤矿乏风瓦斯进行了研究。椰壳经热解制备椰壳炭,考察了椰壳炭易磨性与热解温度的关系,确定了最佳的热解温度。之后利用球磨至一定粒度的粉体椰壳炭为前驱体,酚醛树脂为粘结剂,采用水蒸气为活化剂制备成型活性炭。以制备的活性炭为吸附剂,采用两塔VPSA装置对CH4含量在0.5%左右的乏风瓦斯模拟气进行富集研究,可以将乏风瓦斯富集到1.5%以上,回收率超过96%,废气中CH4含量低于200ppm。采用两塔VPSA工艺和三塔VPSA工艺对含氧煤矿瓦斯进行脱氧试验研究。两塔VPSA工艺脱氧的研究中,选取了两种商业炭分子筛CMS1和CMS2为吸附剂。以CMS1为吸附剂,利用两塔Skarstrom VPSA工艺进行含氧煤矿瓦斯的脱氧,脱氧过程存在安全隐患,同时CH4回收率较低。在吸附阶段后增设置换步骤,能够实现含氧煤矿瓦斯安全有效的脱氧。采用有置换步骤的两塔VPSA工艺,对CMS1和CMS2的脱氧效果进行对比研究,结果表明CMS2具有更高的CH4富集能力,但CH4回收率低,产气中O2浓度也相对较高,而CMS1具有更好的脱氧能力和更高的CH4回收率,但CH4的富集浓度较低。为了实现含氧煤矿瓦斯安全有效地脱氧的同时,提高CH4富集效果,提出了一种分层VPSA工艺,即将CMS1和CMS2两种炭分子筛沿吸附气流的方向在吸附塔内按体积比1：1进行填充。研究结果显示,组成为37.62%CH4、13.10%O2和49.28%N2的原料气,采用分层VPSA工艺分离后,产气中CH4和O2的浓度分别达50.78%和0.44%,废气中CH4浓度为2.62%,CH4回收率达95.9%。对于两塔VPSA工艺,由于吸附塔有效体积小,原料处理量低,原料气及产气都不连续,因此对两塔工艺进行优化,设计并搭建了一套三塔VPSA装置。利用CMS2为吸附剂,考察三塔VPSA工艺对含氧煤矿瓦斯脱氧的效果,结果表明该工艺可以达到含氧煤矿瓦斯安全脱氧的目的,使产气中02浓度由10%左右降低至0.5%以下,废气中CH4浓度低于5%,CH4回收率超过95%,且产气中CH4浓度较原料气中CH4浓度高出10%左右。含氧煤矿瓦斯经脱氧后,产气中CH4浓度仍低于商业管道天然气标准,需要进一步富集。为此在三塔VPSA工艺中,引入了N2的逆向充压、富CH4的逆向置换和逆向均压等步骤。采用改进后的三塔VPSA工艺,一种商业活性炭为吸附剂,对脱氧后煤矿瓦斯进行考察。结果表明对于CH4浓度在40%-50%之间的原料气,随着原料气中CH4浓度的增加,产气中CH4富集效果有所增加,但是CH4回收率降低,产气中CH4浓度可达到95%,回收率超过90%。
[Abstract]:China is the world ' s second largest energy consumption country , in which coal accounts for over 70 % of the energy consumption structure , CH4 quantity discharged by coal mining exceeds 2 billion m3 each year , and the gas concentration of most coal mines can not be directly utilized due to the mixing of large amount of air in the coal mine gas , so that the utilization rate of the coal mine gas is only 10 % . The main component of the coal mine is CH4 , and the direct venting on the one side will pollute the air and cause the greenhouse effect ;
On the other hand , energy can be wasted . Therefore , the research on the separation and enrichment of coal gas is of great practical significance and theoretical value .

The gas ( 0 . 52 % CH4 , N2 balance gas ) , oxygen - containing coal gas ( 10 - 15 % O2 , 30 - 40 % CH4 , N2 balance gas ) and gas ( 40 - 50 % CH4 , N2 balance gas ) in coal mine gas were separated and enriched separately .

It is difficult to find suitable adsorbents to effectively separate N2 and CH4 due to the close physical characteristics of N2 and CH4 . Nine commercial activated carbons , an activated carbon fiber and a 13X molecular sieve are used as adsorbents to study the adsorption thermodynamics and adsorption kinetics of N2 and CH4 on different adsorbents .

In this paper , using coconut shell activated carbon as adsorbent and vacuum pressure swing adsorption ( VPSA ) technology , the coal mine ventilation gas was studied . The best pyrolysis temperature was determined by pyrolysis of coconut shell carbon . The optimal pyrolysis temperature was determined . The activated carbon was used as an adsorbent . The methane content was enriched up to 1.5 % and the recovery rate was more than 96 % . The CH4 content in the exhaust gas was lower than 200 ppm .

In this paper , two kinds of carbon molecular sieves CMS1 and CMS2 were used to deoxidize the gas in oxygen - containing coal mine . The results showed that the concentration of CH4 and O2 in the gas produced by the two - tower VPSA process was lower than that of the oxygen - containing coal mine .

The concentration of CH4 in the gas produced by oxygen - containing coal mine is still lower than that of commercial pipeline natural gas after deoxygenating . In the three - column VPSA process , the reverse charging pressure of N2 , reverse displacement of CH4 rich in CH4 and reverse pressure equalizing are introduced . The results show that CH4 concentration in the produced gas increases with the increase of CH4 concentration in the feed gas , but the CH4 concentration in the gas is 95 % and the recovery rate is over 90 % .
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TD712

【参考文献】