【作者】 张雷；

【导师】 张力；

【作者基本信息】 重庆大学 ， 动力工程及工程热物理， 2015， 硕士

【摘要】 CO2的减排对于缓解全球温室效应有着至关重要意义。在CO2的各种捕集方法中,利用钙基吸收剂对CO2进行脱除是有效的方法之一。在考察合成钙基吸收剂吸收性能时,需要考虑有SO2存在时,同时吸收CO2/SO2循环反应特性。在动力学分析方面,合成钙基吸收剂在吸碳过程中快速反应和慢速反应的动力学以及其在硫化反应和直接硫化反应中的动力学分析都有待进一步分析。针对上述问题展开科学研究,对于钙基吸收剂循环捕集CO2/SO2奠定基础,具有重要的学术意义和应用价值。本文利用湿法混合-煅烧法将具有丰富氧空位的氧化物(Ce O2、Zr O2)掺杂到CO2钙基吸收剂中,并利用热重分析仪(TGA)研究了24种改性钙基吸收剂吸收CO2的循环特性,还研究了添加剂种类、掺杂量、SO2等因素对吸收性能的影响;最后,对改性得到的新型钙基吸收剂进行了吸碳反应、硫化反应以及直接硫化反应进行了宏观动力学分析,获得了新型改性吸收剂在各反应中的反应活化能。研究发现:Ce O2散布在Ca O晶粒之间可抑制晶粒融合,对吸收剂烧结有一定的阻碍作用;Ce O2可明显提高吸收剂在扩散控制阶段对CO2的吸收速率,原因在于Ce O2中丰富的氧空位可促进CO2以离子迁移的方式穿过表面产物层到达内部与Ca O反应;此外吸收剂中Ce O2含量越高,稳定性越强;Zr O2与Ca O高温化合成具有高塔曼温度的Ca Zr O3均匀分散在Ca O晶粒间构成稳固的支撑骨架,有效抑制了吸收剂烧结。烟气中SO2的存在将严重阻碍吸收剂对CO2的捕集。吸收剂CG-1/5CE、CL-1/5ZR的CO2吸收能力随循环数增加而降低,其SO2累计吸收能力却随着循环数的增加而升高。结合实验数据和Arrhenius方程对吸碳过程快速反应阶段、慢速反应阶段以及硫化反应、直接硫化反应进行动力学分析,获得了各个阶段的反应活化能。本文研究钙基吸收剂的制备及其循环吸收CO2、同时捕集CO2/SO2的循环反应特性,得到了高性能钙基吸收剂,并获得了其在硫化反应和直接硫化反应中的反应活化能,为钙基吸收剂同时捕集CO2/SO2的应用提供了理论支撑和依据。更多还原

【Abstract】 It is significant to reduce CO2 emission for preventing global warming.Among technologies of carbon emission reduction, calcination/carbonation reaction is one of the effective methods. For new synthesized sorbents, cyclic reaction characteristic for co-capture CO2/SO2 should be investigated. In terms of dynamics analysis, the separation of rapid and slow reaction step for carbonation process, carbonation kinetics for calcium-based sorbents,and the kinetics of sulfuration and direct sulfuration should be further studied. The above scientific questions are focused and studied. The results can provide theoretical support for co-capture CO2/SO2 with calcium-based sorbents. It has important academic and application vales.Ca O-based sorbents with oxygen vacancy-enriched Ce O2 and Zr O2 as dopants were prepared by the method of wet mixing and the subsequent calcination. Then the cyclic CO2 sorption/desorption performance of the total 24 sorbents was tested with a thermogravimetric analyzer(TGA).The effect of variety and amount of additives, SO2 and other factors on adsorption performance are also investigated.Finally, the kinetics of rapid and slow reaction step for carbonation process and the kinetics of sulfuration and direct sulfuration have be studied. The activation energy of those reaction for sample CL-1/5ZR were obtained.The results show that Ce O2 could accelerate the CO2 sorption rate in the diffusion-controlled regime because that the large quantity of oxygen vacancies in Ce O2 could facilitate the CO2 diffusion through the produced Ca CO3 layer and then react with the uncreated Ca O. The dispersion of Ce O2 on Ca O could also inhibit the agglomeration of Ca O crystal and its sintering under high temperature. It shows that the stability of Ca O in sorption/desorption cycle increase with the rise of the amount of Ce O2 in the sorbents. With a high tammann temperature, the newly produced Ca Zr O3 from zirconia and calcium oxide, could serve as a supporting framework and effectively retrain the sintering. SO2 markedly reduces the CO2-capture capacity for multiple cycles. CO2 capture capacity for CG-1/5CE and CL-1/5ZR decreased as sorption/desorption cycles increased, while the SO2 capture increased with cycles. With combining experimental data and Arrhenius equation, the kinetics of rapid and slow reaction step for carbonation process and the kinetics of sulfuration and direct sulfuration have be studied. The activation energy of those reaction for sample CL-1/5ZR were obtained.In this work, a series of investigations for calcium-based sorbents was taken systematically, such as preparation of synthesis sorbents and cyclic reaction characteristics for CO2 capture and simultaneous CO2/SO2 capture. A new calcium-based sorbent with high reaction capacity was obtained. The activation energy of sulfuration and direct sulfuration for sample CL-1/5ZR was also achieved.更多还原