【作者】 杨洁；

【导师】 严晋跃；

【作者基本信息】 华东理工大学 ， 动力工程及工程热物理， 2014， 博士

【摘要】 由化石燃料燃烧释放出的CO2等温室气体导致的气候变化,给地球的生态环境和人类的生存条件带来严重的威胁。化石燃料在供热发电和重工业制造领域将仍然发挥重要的作用。CO2捕集和存储(固定)(CCS)技术是短期内有效减少CO2排放的可能途径。适用于具有低压低浓度CO2特点的燃煤电厂燃烧后烟道气CO2捕集的低操作成本和低能耗的新技术非常具有研究价值和应用前景。本论文采用膜气吸收高效CO2吸收器和离子液体低能耗吸收液,并提出耦合CO2吸收的微藻油高效提取新工艺,围绕烟道气杂质影响、系统连续运行稳定性、工艺能耗降低等问题,进行了实验研究和理论计算。本文的主要研究内容和结论有以下三个方面：建立了实验室规模的CO2连续吸收-解吸实验装置。采用中空纤维膜接触器作为CO2吸收器,单乙醇胺(MEA)水溶液作为吸收液,研究了燃煤电厂烟道气中SO2和O2杂质对膜接触器CO2吸收系统的影响。实验结果表明气源中SO2和O2的引入,会增加MEA的降解。吸收每吨CO2, MEA损失量分别为：CO2-N2组为1.3kg, CO2-O2(6%)-N2组为3.32kg, CO2-SO2(294ppm)-N2组为4.72kg, CO2-O2(6%)-SO2(30ppm)-N2组为4.49kg。混合气中微量的SO2浓度对吸收液中MEA的降解的影响比O2更显著。在满足我国对燃煤电厂SO2排放要求的基础上吸收液中MEA损失主要为MEA蒸发所引起。为降低MEA蒸发损失及CO2解吸能耗,研制了MEA+离子液体+水混合吸收液。研究发现30wt%MEA+40wt%[bmim][BF4]+30wt%H2O的吸收液可将MEA的损失量降低至1.16kg/ton CO2,并且没有观察到离子液体损失。30wt%MEA+40wt%[bmim][BF4]+30wt%H2O吸收液可保持90%以上的CO2吸收效率,再生能耗比30wt%MEA水溶液低37.2%。该种混合液在50℃下的粘度仅为3.54mPa-s,吸收液所降低的再生能耗能够远超过其高粘度引起的吸收液输送机械能耗的上升。结合离子液体高CO2溶解度的特性与其在藻细胞破壁上的特点,提出了基于离子液体的耦合CO2吸收与薇藻油脂高效提取的新工艺过程。实验结果表明耦合CO2有助于离子液体水解微藻细胞壁。当离子液体[bmim][BF4]吸收CO2后,微藻油的产率从14.2wt%提高到15.6wt%。考虑吸收的CO2对微藻油提取所补偿的能耗,耦合CO2吸收的使用离子液体的微藻油提取工艺的能耗最高能降低至传统溶剂法的10%,理论上可实现基于微藻和离子液体的烟道气CO2昼夜连续吸收。即,白天微藻吸收CO2进行光合作用,晚上吸收CO2进行微藻油的提取。更多还原

【Abstract】 Global warming caused by CO2emission from fossil combustion is threatening the ecological environment and human survival. Fossil fuels will continue to play an important role in both generation of heat and power and in heavy industrial manufacturing operations for the foreseeable future. Carbon capture and storage (CCS) is promising to achieve a meaningful reduction in CO2emissions in the short term. Post-combustion CO2capture with low cost and energy consumption needs to be further studied. In this dissertation, the effects of impurities on CO2capture using a hollow fiber membrane contactor, the performance of amine+ionic liquid+water absorbent used in an CO2absorption/desorption system, and the feasibility of fuel extraction from algae combined with CO2absorption have been systemically investigated. The main contents and conclusions are as follows:With a polypropylene (PP) hollow fiber membrane contactor as absorber and a packed column as stripper, the influence of SO2and O2on the CO2capture from coal-fired power plant flue gas was investigated in an absorption-desorption experimental set-up using aqueous monoethanolamine (MEA) as the absorbent. The experimental results showed that the MEA loss per ton captured CO2of each campaign with different gas source was:CO2-N2:1.3kg, CO2-O2(6%)-N2:3.32kg, CO2-SO2(294ppm)-N2:4.72kg, CO2-O2(6%)-SO2(30ppm)-N2:4.49kg. SO2in the flue stream plays a more important role than O2in CO2capture. When the SO2concentration of flue stream under30ppm which meets the requirement by national standard, the largest contribution to monoethanolamine loss was made by evaporation during desorption, followed by the formation of sulfate and heat stable salts.To reduce MEA loss and meanwhile lower down the energy consumption during CO2desorption, an aqueous amine solution mixed with ionic liquid (30wt%MEA+40wt%[bmim][BF4]+30wt%H2O) was proposed. The energy consumption of the mixed ionic liquid solution for absorbent regeneration was37.2%lower than that of aqueous MEA solution. The MEA loss per ton of captured CO2for the mixed solution was reduced to1.16kg. No ionic liquid loss was detected. In addition, the mixed ionic liquid solution showed a low viscosity of3.54mPa·s at50℃, indicating that the ionic liquid disadvantage of high viscosity can be overcome for absorbent delivery of CO2capture.The abilities of CO2capture and lipids extraction by algae+IL system were utilized to decrease the energy consumption. Chlorella hydrolysis integrating CO2removal by ILs ([bmim][BF4],[bmim]Cl and [amim]Cl) was demonstrated in this study. The addition of CO2to [bmim][BF4] can increase the lipids yield from14.2wt%to15.6wt%. The value of net energy gain increased from9.41to11.7with the CO2addition to [bmim][BF4]. Considering the compensated energy by CO2capture, the energy consumption of algae fuel extraction process integrating CO2absorption could be decreased to be10%of that of conventional solvents extraction process.更多还原