引用本文:李延霞,李杨,沈龙,汪洋,张银德,申小冬. N-甲基二乙醇胺溶液中CO2气体吸收与水合物生成特性实验研究[J]. 石油与天然气化工, 2024, 53(3): 79-85.
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N-甲基二乙醇胺溶液中CO2气体吸收与水合物生成特性实验研究
李延霞1,李杨1,沈龙1,汪洋2,张银德1,申小冬1
1.成都理工大学油气藏地质及开发工程全国重点实验室 ;2.中国石油西南油气田公司川东北气矿
摘要:
目的酸性气田开发气流中往往含有二氧化碳(CO2)和硫化氢(H2S)等酸性组分,易形成天然气水合物(简称水合物),引起管道堵塞。解决酸性组分吸收剂对水合物作用机制不明确问题,为脱除酸性气体组分并防治水合物生成提供理论依据。 方法 采用恒温恒容法研究了N-甲基二乙醇胺(MDEA)溶液质量分数、搅拌状态及初始压力对CO2气体吸收规律的影响、MDEA溶液对CO2水合物生长速率和宏观晶体形态的影响,并与传统热力学抑制剂乙二醇(EG)效果进行对比。 结果CO2气体吸收量随MDEA溶液质量分数的增加表现为先增后减的趋势。开启搅拌和降低压力可加快CO2气体的吸收速率,增加气体吸收量。在气液界面,水合物晶体以二维模式生长,并且MDEA可改变CO2水合物的宏观形貌,增加其质量分数可显著增加CO2水合物覆盖溶液表面的时间、降低CO2水合物的生长速率。与EG相比,MDEA水合物的动力学抑制效果较差,但水合物膜覆盖时间较长,生长速率较慢。 结论MDEA可与溶液中水分子形成氢键,与水合物竞争水分子,减少水的活性,同时,MDEA分子可与CO2分子结合,与水合物竞争CO2,显著降低水合物生长速率。研究结果对酸性气体的分离捕获和天然气流动的安全保障具有理论指导意义。 
关键词:  N-甲基二乙醇胺  气体溶解  水合物  生长速率  宏观形态 
DOI:10.3969/j.issn.1007-3426.2024.03.013
分类号:
基金项目:国家自然科学基金青年基金项目“改性多糖对深水钻井液中水合物稳定性的传质调控机理研究”(42002308);中国科学院天然气水合物重点实验室开放基金“Ⅰ型和Ⅱ型气体水合物差异化动力学抑制机理研究”(E029kf1201)
Experimental study on CO2 gas absorption and hydrate formation of N-methyldiethanolamine solution
LI Yanxia1, LI Yang1, SHEN Long1, WANG Yang2, ZHANG Yinde1, SHEN Xiaodong1
1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, Sichuan, China;2. Northeast Sichuan Gas District, PetroChina Southwest Oil & Gasfield Company, Dazhou, Sichuan, China
Abstract:
ObjectiveThe gas flow during the exploitation of sour gas fields often contains sour components such as carbon dioxide (CO2) and hydrogen sulfide (H2S), which are easy to form natural gas hydrates (hydrate for short) and cause pipeline blockages. The aim is to solve the problem of unclear mechanisms of sour component absorbers on hydrates, which could provide a theoretical for removing sour gas components and preventing hydrate formation. Methods In this paper, the isothermal and isochoric methods investigated the effects of the mass fraction, stirring state, and initial pressure of N-methyldiethanolamine (MDEA) solution on the absorption law of CO2. The effects of MDEA solution on the growth rate and macroscopic morphology of CO2 hydrate were also studied and compared to the conventional thermodynamic inhibitor ethylene glycol (EG). ResultsThe study indicated that the absorption rate of CO2 showed a trend of increasing and then decreasing with the increase of the mass fraction of the MDEA solution. The stirring state and lower initial pressure could accelerate the absorption rate of CO2 and increase the amount of gas absorption. At the gas-liquid interface, hydrate crystals grew in a two-dimensional mode, and MDEA could change the macroscopic morphology of CO2 hydrates. Increasing the mass fraction of MDEA solution could significantly increase the time for CO2 hydrates to cover the surface of the solution and reduce the growth rate of CO2 hydrates. In contrast to the EG, the kinetic inhibition of MDEA hydrates was poorer, but the cover time of the hydrates film was longer, and the growth rate was slower. Conclusions It is analyzed that MDEA could form hydrogen bonds with water molecules in the solution and compete with hydrates for water molecules, reducing water activity. It could also combine with CO2, and compete with hydrates, significantly decreasing the growth rate of hydrate. The research results have theoretical significance for the guidance of the separation and capture of sour gases and natural gas transportation.
Key words:  N-methyldiethanolamine  gas absorption  hydrate  growth rate  macroscopic morphology