【作者】 黄洪；

【导师】 樊栓狮；

【作者基本信息】 华南理工大学 ， 化学工程与技术， 2022， 硕士

【摘要】 注CO₂强化回收页岩气、天然气水合物、煤层甲烷以及驱油获得油田伴生气既可提高油气资源的开采效率,也可封存温室气体CO₂,通过注CO₂强化油气资源开采过程得到的产品气通常为富CO₂/CH₄气,因此,经济地捕获富CO₂/CH₄混合气中CO₂具有重要的实际意义。水合捕获CO₂技术具有工艺简单、能耗低、绿色无污染等优点,但水合捕获富CO₂/CH₄气中CO₂鲜见报道。本文在分析了实验条件对水合捕获CO₂能耗的基础上,使用CO₂/CH₄（90:10）模拟富CO₂/CH₄气,探究添加剂浓度、过冷度、气液比及压力等因素对水合捕获CO₂结果的影响,并设计了新型喷射水合反应器以强化水合捕获CO₂过程动力学。首先,采用ASPEN软件分析水合捕获CO₂工艺能耗,结果表明:两级水合物形成压力从4 MPa降至1 MPa时,工艺能耗降低18.1%,低压操作可显著降低工艺能耗;（火用）损失最大的两部分为两级水合物生成和分解单元,（火用）损失大于73%;降低水合物生成过程所需的制冷能量,合理有效利用水合物分解单元释放的冷能,是提高工艺（火用）效率的重点。工艺优化后,能耗可降至0.451 kWh/kg _CO2,与传统的吸收法和变压吸附等技术相比具有明显优势。其次,采用定容（温度压力搜索）法测定CO₂/CH₄（90:10）在不同体系下水合物相平衡条件,结果表明:当添加5 wt%的TBAB后,CO₂/CH₄（90:10）二组气水合物的相平衡条件在相同压力下相较水体系提高约5-8 K,此结果为水合捕获CO₂实验提供基础物性数据。然后,通过注液维持恒压水合捕获富CO₂/CH₄混合气中CO₂,结果表明:在相同实验条件下,与非恒压操作相比,恒压操作下可直接将残余气相CH₄浓度从10 mol%提高至66.2 mol%;在恒压2 MPa、6 K过冷度和5 wt%TBAB的添加剂浓度条件下进行的实验具有最佳捕获效果,CO₂捕获率最高可达97%,CO₂分离因子最高可达37;与现有报告数据相比,恒压操作实现了在较低压力下温和捕获富CO₂/CH₄混合气中CO₂。最后,喷射水合反应器中捕获CO₂的实验研究结果表明:在5 wt%TBAB体系中,喷射强化可以显著提高气液传质效率,喷射强化实验在3 MPa下可达到197.61 h^-1的最大空速,相比其他文献报道数据高约一个数量级;在2 min内喷射强化的气体消耗量大约是搅拌强化的4倍。TBAB体系实验中水合物生成后会导致设备管路堵塞,在乳液体系中,水合物浆液流量表现稳定,体系浆液流量可稳定在2 L/min左右,使用乳液体系可解决管路堵塞问题。综合考虑,乳液体系在2 MPa和6 K过冷度时下的捕获结果是最高效的。此时,CO₂捕获率超过70%,且CH₄回收率约70%。本论文为捕获富CO₂/CH₄混合气中CO₂实验室研究方向和水合物法气体连续捕获CO₂工艺提供了一定程度的参考。更多还原

【Abstract】 CO₂ injection and enhanced recovery of shale gas,oilfield associated gas,coalbed methane and natural gas hydrate can not only improve the exploitation efficiency of oil and gas resources,but also store greenhouse gas CO₂.However,the product gas obtained by CO₂ injection enhancement exploitation process of oil and gas resources is usually rich CO₂/CH₄ mixture.Therefore,it is of great practical significance to economically capture CO₂ in rich CO₂/CH₄.Hydrate-based CO₂capture technology has the advantages of simple process,low energy consumption,green and pollution-free,but the report on hydrate-based CO₂ capture from rich CO₂/CH₄ is slightly insufficient.Based on the analysis of the influence of experimental conditions on the energy consumption of Hydrate-based CO₂ capture from CO₂/CH₄,this paper uses CO₂/CH₄（90:10）to simulate rich CO₂/CH₄,and explores the influence of factors such as concentration of promoter,undercooling,gas-liquid ratio and pressure on the hydrate-based CO₂ capture efficiency.This paper also designed a jet reactor to enhance the kinetics of hydrate-based CO₂ capture process.First of all,the energy consumption of hydrate-based CO₂ capture from CO₂/CH₄is analyzed by Aspen software.The results show that when the formation pressure of two-stage hydrate is reduced from 4 MPa to 1 MPa,the energy consumption of the whole process is reduced by 18.1%,and the low-pressure operation can significantly reduce the energy consumption of the process;The two largest parts of exergy loss are the two-stage hydrate formation and decomposition unit,and the exergy loss is more than 73%;Reducing the refrigeration energy required in the hydrate formation process and making rational and effective use of the cold energy released by the hydrate dissociation unit are the key points to improve the process efficiency.After process optimization,the energy cost can be reduced to 0.451 kWh/kg _CO2,which has obvious advantages compared with traditional absorption method and pressure swing adsorption technology.In the second place,phase equilibrium determination:constant volume（temperature and pressure search）method is used to determine the phase equilibrium conditions of CO₂/CH₄（10:90）hydrate in different systems.The results show that when 5 wt%TBAB is added to CO₂/CH₄（10:90）,the phase equilibrium condition of hydrate is about 5-8 K higher than that of H₂O system at the same pressure.This result provides basic physical property data for CO₂ capture experiment.Secondly,the results show that under the same experimental conditions,compared with non-constant pressure operation,the residual gas phase CH₄concentration can be increased from 17.2 mol%to 66.2 mol%under constant pressure operation,and the experiments carried out under constant pressure 2 MPa,6K undercooling and 5 wt%TBAB additive concentration have the best separation effect.The maximum CO₂ capture rate and CO₂ separation factor can reach 97%and37,respectively.Compared with the existing reported data,the constant pressure operation achieves high efficiency and mild CO₂ capture at lower pressure.In the end,experimental study on CO₂ capture via hydrate-based jet reactor in 5wt%TBAB system,jet strengthening can significantly improve the gas-liquid mass transfer efficiency.The jet strengthening experiment can reach the maximum space velocity of 197.61 h^-1 at 3 MPa,which is about one order of magnitude higher than the data reported in other literatures.The gas consumption of injection strengthening in 2 minutes is about 4 times that of stirring strengthening.In the experiment with 5wt%TBAB,the formation of hydrate will lead to the blockage of equipment pipeline.In the emulsion system,the flow rate of hydrate slurry is stable,and the slurry flow rate of the system can be stabilized at about 2 L/min.The plugging problem of the pipeline can be solved by using the emulsion system.In general,the CO₂ capture results of emulsion system at 2 MPa and 6 K undercooling are the most efficient.The CO₂ capture rate is more than 70%,and the CH₄ recovery rate is about 70%.This work not only provides reference for hydrate-based CO₂ capture laboratory research and hydrate-based CO₂ continuous capture process.更多还原