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离子液体法脱碳工艺的模拟与能耗分析
刘芯妍
学位类型硕士
导师张香平 ; 张锁江
2016-07
学位授予单位中国科学院研究生院
学位授予地点北京
学位专业化学工程
关键词脱碳 离子液体 醇胺溶液 Cosmo-rs模型 流程模拟 能耗分析
摘要

随着煤炭资源的大量消耗,天然气、页岩气和生物气等替代资源的开发日益受到重视。该类气体除含有大量甲烷(CH4)外,还含有二氧化碳(CO2)及其他酸性气体杂质,在用作机动车燃料或注入天然气管网之前,进行脱碳提质是十分必要的。作为一种新型的溶剂,离子液体(ILs)因其低饱和蒸汽压、对CO2的高溶解度,且再生能耗低等特性而具有大规模脱除CO2的潜力。然而,离子液体体系庞大,种类繁多,用实验方法筛选出CO2溶解度高,甲烷分离性能好的ILs具有较大难度。本论文采用真实溶剂似导体屏蔽(COSMO-RS)模型,在实验数据的基础上筛选适用于大规模脱除CO2的IL。在此基础上设计模拟了IL法脱碳的流程,开展了过程的能耗分析以及与传统醇胺溶液脱碳流程的对比。为新工艺的设计提供了科学依据,具有重要的理论意义和实用价值。本论文的创新性成果如下:(1)在COSMO-RS模型的基础上,预测了CO2和CH4在9种阳离子和10种阴离子组成的ILs中的亨利系数以及选择性。结果表明,阳离子上碳链越长,则与CO2分子间的作用力越大,越有利于吸收CO2,进一步,结合IL粘度以及毒性数据库,筛选出了适合甲烷气脱碳的IL,为开发新型IL脱碳工艺提供基础数据。(2)针对筛选的IL,建立了适用于分离页岩气中CO2的热力学模型,获得与文献数据一致的气液平衡结果。建立了两级闪蒸、多级闪蒸IL脱碳工艺以及传统醇胺溶液(MDEA)脱碳工艺流程,通过流程模拟及灵敏度分析确定了溶剂消耗、能量消耗等工艺参数。结果表明,IL多级闪蒸工艺能节约大量66%能耗,是一种极具潜力的脱碳节能新工艺。 (3)基于上述的IL页岩气脱碳工艺,进一步对CO2含量更高的生物沼气脱碳工艺进行了流程模拟,通过灵敏度分析优化了装置压力,确定了各装置较优操作条件,并与中试实验数据进行了对比,模拟结果与实验基本一致。进一步优化表明,对两级闪蒸罐提供一定热量,有助于气体的解吸,从而有效降低CH4损失率,提高CO2脱除率,从而提供了一种技术可行的生物气脱碳提质工艺方案。

其他摘要

With the large consumption of coal, it is necessary to search for other energy supply alternatives, such as shale gas, natural gas, and biogas.Those kind of gas mixture mainly consists of CH4, CO2 and other impurities such as N2, light hydrocarbons. It is a necessary step for gas mixture upgrading aiming at removing CO2 and other impurities before being used on a large scale or commercialized. As a new kind of solvent, ionic liquid (IL) has been considered as new potential solvent for CO2 removal because of its low saturated vapor pressure, high solubility of CO2 and low energy consumption of recycle. In this work, a more comprehensive and systematic method is proposed to screen suitable ILs than previously reported works based on the COSMO-RS model, absorption mechanism as well as available experimental data. Further, a comparison was made between IL-based decarbonization process with MDEA process on energy consumption. The work provides basic data package for the process design, and guidance for the process optimization. The innovative results of the dissertation are as follows.(1) Based on COSMO-RS model, the henry's constant of CO2 and CH4 and selectivity of CO2/CH4 in 9 cations and 10 anions were predicted. The results showed that the solubility of CO2 increases with the length of alkyl chain in the cation of same kind of ILs. Combined with the ILs database, the viscosity and toxicity of imidazolium ILs were evaluated. The potential IL for decarbonization was screened under the consideration of those properties, providing fundamental for process design and optimization.(2) According to the screened IL,thermodynamics model for shale gas separation was established and the predicted values were consistent with the literature.The two-stage flash and multi-stage flash of IL-based decarbonization process and MDEA-based process were simulated. Detailed process parameters of the three technologies were obtained through sensitivity analysis. The results showed that multi-stage flash process could save much energy consumption, which may be a potential substitute for MDEA-based technology.(3) Based on the IL-based process for shale gas decarbonization, a similar process for biogas decarbonization was simulated through sensitivity analysis and optimization. The optimal operation condition was set, providing important guidance for the establishment of pilot plant. The result showed that adding a little heat in flash could effectively reduce the CH4 loss and increase the CO2 removal. 

语种中文
文献类型学位论文
条目标识符http://ir.ipe.ac.cn/handle/122111/22868
专题研究所(批量导入)
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刘芯妍. 离子液体法脱碳工艺的模拟与能耗分析[D]. 北京. 中国科学院研究生院,2016.
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