洁净煤技术

2019, v.25;No.124(06) 78-87

[打印本页] [关闭]
本期目录(Current Issue) | 过刊浏览(Past Issue) | 高级检索(Advanced Search)

变压吸附法提纯煤层气中甲烷研究进展
Research progress on the recovery of methane from coalbed methane by pressure swing adsorption

张进华;曲思建;王鹏;李雪飞;李兰廷;车永芳;李小亮;
ZHANG Jinhua;QU Sijian;WANG Peng;LI Xuefei;LI Lanting;CHE Yongfang;LI Xiaoliang;School of Chemical and Environmental Engineering,China University of Mining&Technology(Beijing);Coal Chemistry Branch of China Coal Research Institute;Beijing Key Lab of Coal Based Energy Conservation and Enviroment Protective Carbon Material;State Key Laboratory of Coal Mining and Clean Utilization;

摘要(Abstract):

低浓度煤层气直接排放既造成能源浪费,又带来严重的温室效应,变压吸附法提纯低浓度煤层气是解决煤层气排放的有效利用途径。总结了变压吸附技术对CH_4/N_2体系煤层气中CH4分离的研究进展,包括变压吸附分离机理和相应的变压吸附提纯工艺路线,分析了2种工艺的优缺点,讨论了多孔吸附材料,如活性炭、碳分子筛、沸石分子筛和金属有机骨架材料对CH_4/N_2吸附分离效果的研究进展和存在的问题。基于平衡效应分离的变压吸附技术,在CH_4/N_2体系分离实际应用中遇到瓶颈,原因在于现有吸附剂平衡分离系数太小,提浓幅度有限;其次,CH_4在平衡效应里作为强吸附组分被优先吸附,产品气必须通过抽真空的方式解吸获得,必须采取多级压缩和增加置换步骤,因而能耗相对较高。基于动力学效应的分离,可在塔顶直接获得富集的带压产品气;同时免去多级压缩的能量消耗,相对平衡效应分离具有显著优势,但需要在第一级加压,处理接近爆炸限浓度煤层气有一定安全隐患。活性炭吸附容量大,处理能力强,价格低廉,是一种典型的平衡分离型吸附剂,但分离系数较低,存在气体循环量大、效率低,提浓幅度窄等缺点,如何通过孔径调控和表面改性提高活性炭的平衡分离系数将是今后研究的重点。现有报道效果较好的动力学吸附剂主要以碳分子筛为主,但价格高昂,工业推广受限,选择合适的廉价原料、改变现有间歇式生产工艺、进一步开发高效、廉价的动力学/N2的重要方向。沸石分子筛会优先吸附CH_4,与动力学效应优先吸附N_2相反,降低了分子筛对CH_4/N_2的分离选择性。所以硅铝分子筛/钛硅分子筛多在分离高浓度CH4含量的天然气、油田气方面表现优异,针对低浓度煤层气CH_4的提纯应用较少,未见工业应用报道。金属有机骨架材料的出现提供了新的发展思路,但其在CH_4/N_2的吸附平衡和动力学研究以及变压吸附分离方面研究较少,还有待进一步深入研究,解决材料的稳定成型和放大仍是需要突破的技术瓶颈。未来变压吸附提纯工艺将是平衡效应和动力学效应的组合工艺,开发低压下变压吸附分离工艺将具有更好的经济性和安全性;低成本、大容量、高选择性吸附剂开发仍是未来吸附剂的重点发展方向;同时吸附剂寿命以及再生性能有待深入研究。
The direct emission of low-concentration coal bed methane not only causes energy waste,but also brings serious environmentalharm such as greenhouse effect.The purification of low concentration coalbed methane by PSA is an effective way to solve the emission of coalbed methane.In this paper,the research on separation of methane from CH_4/N_2 system in coalbed methane using the technology ofpressure swing adsorption was summarized,including separation mechanism and the corresponding pressure swing adsorption purificationtechnology;the advantages and disadvantages of two kinds of technology were analyzed,and the research progress and existing problems ofCH_4/N_2 adsorption separation effect on porous adsorption materials were discussed such as activated carbon,carbon molecular sieve,zeo-lite molecular sieve and metal organic skeleton materials.Pressure swing adsorption technology based on equilibrium effect separation hasencountered a bottleneck in the practical application of CH_4/N_2 system separation since the equilibrium separation coefficient of existingadsorbents is too small and the concentration enhancement is limited.Secondly,CH4 is preferentially adsorbed as a strong adsorption com-ponent in the equilibrium effect. The product gas must be obtained by vacuum desorption,and multistage compression and additional dis-placement steps must be taken,so the energy consumption is relatively high. The enriched product gas with pressure can be directly ob-tained at the top of the towerbased on the separation of dynamic effect,meanwhile,the energy consumption of multi-stage compression isavoided,and it has a significant advantage comparing with the equilibrium effect separation. However,since the first stage is required to bepressurized,there are some safety risks in the treatment of coal-bed methane near the explosion limit concentration.Activated carbon is atypical equilibrium separation adsorbent with large adsorption capacity,strong processing capacity,and low price,but the separation coeffi-cient is low,and activated carbonhas the disadvantages of large gas circulation volume,low efficiency,and narrow concentration range. Howto improve the equilibrium separation coefficient of activated carbon through pore size control and surface modification will be the focus offuture research.Currently,carbon molecular sieves have been reported to be the main kinetic adsorbents with good results. However,due totheir high price and limited industrial promotion,it will be an important direction for pressure swing adsorption to separate CH_4/N_2 in thefuture by selecting appropriate and cheap raw materials,changing the current intermittent production process,and further developing effi-cient and cheap kinetic selective adsorbents.Zeolites preferentially adsorb methane,in contrast to kinetic effects which preferentially adsorbnitrogen,which reduce the separation selectivity of CH_4/N_2.Therefore,Si-Al zeolites/Ti-Si zeolites mostly perform well in the separationof natural gas and oilfield gas with high concentration of CH_4,while it is rarely applied in the purification of CH_4 with low concentration ofCBM,and there is no industrial application report.The emergence of metal-organic framework materials provides a new development idea,but there arethe few research on CH_4/N_2 adsorption balance and kinetics as well as pressure swing adsorption separation,which need to befurther studied. Therefore,the solution of stable forming and amplification of materials is still a technical bottleneck to be broken through.The author believes that the future pressure swing adsorption purification process will be a combination of equilibrium effect and kineticeffect,and the development of separation process under low pressure will have better economy and safety.The development of low cost,high capacity and high selectivity adsorbent is still the key development direction of adsorbent in the future. The adsorbent life and regener-ation performance need to be further studied.

关键词(KeyWords): 煤层气;甲烷;变压吸附;吸附剂
coalbed methane;methane;pressure swing adsorption;adsorbent

Abstract:

Keywords:

基金项目(Foundation): 国家重点研发计划资助项目(2018YFB0605604);; 国家科技重大专项资助项目(2016ZX05045-005)

作者(Author): 张进华;曲思建;王鹏;李雪飞;李兰廷;车永芳;李小亮;
ZHANG Jinhua;QU Sijian;WANG Peng;LI Xuefei;LI Lanting;CHE Yongfang;LI Xiaoliang;School of Chemical and Environmental Engineering,China University of Mining&Technology(Beijing);Coal Chemistry Branch of China Coal Research Institute;Beijing Key Lab of Coal Based Energy Conservation and Enviroment Protective Carbon Material;State Key Laboratory of Coal Mining and Clean Utilization;

Email:

DOI:

参考文献(References):

文章评论(Comment):

序号(No.) 时间(Time) 反馈人(User) 邮箱(Email) 标题(Title) 内容(Content)
反馈人(User) 邮箱地址(Email)
反馈标题(Title)
反馈内容(Content)
扩展功能
本文信息
服务与反馈
本文关键词相关文章
本文作者相关文章
中国知网
分享