【作者】 孙荣岳；

【导师】 路春美；

【作者基本信息】 山东大学 ， 热能工程， 2013， 博士

【摘要】 本文提出利用大宗钙基废弃物作为燃煤电站CO2吸收剂进行循环煅烧/碳酸化捕集C02,就有望实现钙基废弃物资源化与低成本捕集C02相结合的新型工艺路线。为了实现这一工艺路线,需要对其循环捕集C02性能和反应机理进行研究。在双固定床反应器系统(DFR)上研究了钙基废弃物循环捕集CO2特性,在热重分析仪(TGA)上考察了钙基废弃物碳酸化反应动力学。为了进一步提高钙基废弃物循环捕集CO2性能,采用分级水洗预处理、延长碳酸化和丙酸改性对钙基废弃物进行处理,通过SEM、氮吸附等微观分析手段揭示了改性机理。在流化床反应器系统(BFR)上研究了流态化下钙基废弃物循环反应过程中的CO2捕集性能和颗粒磨损特性。与赤泥等其他钙基废弃物相比,电石渣和造纸白泥具有较高的循环捕集CO2性能。煅烧电石渣比表面积以及>150nnm范围内的比孔容大于煅烧石灰石,碳酸化反应比石灰石更容易进行,其捕集CO2性能优于石灰石。白泥孔隙主要分布在1-10rim范围,在碳酸化过程中容易发生堵塞,所以初始几次循环捕集CO2能力不高,但是随循环次数增加,孔隙结构比较稳定,15次循环后碳酸化转化率高于石灰石。考察了反应温度、碳酸化气氛和颗粒粒径等反应条件对钙基废弃物循环碳酸化特性的影响规律,探讨了钙基废弃物循环碳酸化动力学特性。为避免S02存在对钙基废弃物捕集CO2造成的不利影响,提出了钙基废弃物顺序捕集SO2/CO2的方法,并研究多次循环煅烧/碳酸化捕集CO2后钙基废弃物的硫酸化特性。在CaCO3中掺入各种杂质,研究杂质成分对钙基废弃物循环捕集CO2性能的影响。研究发现Mn和Cl对钙基废弃物的捕集CO2性能影响较大。添加Mn后,CaCO3高温煅烧时形成更发达孔隙结构,循环捕集CO2性能更高,最佳Mn/Ca摩尔比为1：100-1.5：100。当Cl/Ca摩尔比超过0.25：100时,C1使10-100nnm内孔大幅度减少,抑制了CaCO3循环捕集CO2性能。白泥中Cl/Ca摩尔比为2.6：100,循环捕集C02性能不高主要由于其C1含量较高所致。鉴于钙基废弃物中Cl对捕集CO2的不利影响,提出分级水洗预处理方法降低C1在钙基废弃物中含量。水洗白泥的C1含量大幅降低,循环捕集C02能力明显提高。100次循环后,水洗白泥碳酸化转化率为0.36,是白泥的1.8倍。延长碳酸化可提高钙基废弃物循环捕集C02性能。增加碳酸化时间和提高碳酸化气氛中C02浓度可使延长碳酸化处理效果更加明显。在循环煅烧/酸化过程中对钙基废弃物进行多次延长碳酸化可使其保持较高C02捕集性能。丙酸改性提高了钙基废弃物循环碳酸化转化率以及碳酸化速率,第30次循环丙酸改性电石渣碳酸化转化率为0.47,为未处理电石渣的1.5倍。3种改性方法优化了钙基废弃物的孔隙结构,特别是煅烧钙基废弃物10-100nm范围内对碳酸化反应有利的孔大幅增加,这是钙基废弃物循环捕集C02性能提高的主要原因。在流态化条件下以电石渣为典型代表研究了钙基废弃物循环反应过程中的颗粒磨损特性。电石渣颗粒在循环煅烧/碳酸化过程中不断磨损,磨损速率随循环次数增加逐渐降低。煅烧温度对电石渣磨损特性影响较大,高温煅烧时颗粒磨损更加严重。电石渣磨损速率与流化数平方成正比,随流化数增加磨损速率迅速升高。大粒径电石渣颗粒磨损更加严重。电石渣磨损速率常数kImp值小于石灰石,抗磨损性能优于石灰石。更多还原

【Abstract】 Calcium-based industrial wastes were proposed as CO2sorbents in calcium looping process for post-combustion CO2capture in coal-fired power plant in this paper. A novel process that can combine effective reuse of the calcium-based industrial wastes and low-cost CO2capture together is hoping to be achieved. It is necessary to investigate the CO2capture behavior and reaction mechanism of calcium-based industrial wastes in calcium looping process.A dual fixed-bed reactor (DFR) was employed to investigate the CO2capture behavior of calcium-based industrial wastes, and a thermal gravimetric analysis (TGA) was used to examine the carbonation kinetics of the calcium-based industrial wastes. Pre-wash treatment, prolonged carbonation and modification by propionic acid were proposed to improve the CO2capture capacity of the calcium-based industrial wastes in multiple calcination/carbonation cycles. SEM analysis and N2adsorption method were employed to reveal the mechanism of the enhancements. The CO2capture capacity and the particle attrition characteristics of the calcium-based industrial wastes in the cycles under fluidization condition were investigated in a bubbling fluidized reactor (BFR).Carbide slag and lime mud show higher CO2capture capacity than other calcium-based industrial wastes like red mud. The surface area and volume of pores>150nm of the calcined carbide slag are larger than those of calcined limestone, the carbonation reaction of CaO derived from the carbide slag is easier than that from the limestone. The cyclic CO2capture capacity of the carbide slag is better than the limestone. The pores of the calcined lime mud are mainly distributed in1-10nm, which are susceptible to pores blockage and plugging in carbonation process. Therefore, the CO2capture capacity of the lime mud is relatively low during the initial cycles. However, the microstructure of calcined lime mud is very stable during multiple calcination/carbonation cycles, and the carbonation conversion of the lime mud is higher than limestone after15cycles. The effects of reaction temperature, carbonation atmosphere and particle size were discussed. The cyclic carbonation kinetics of the calcium-based industrial waste was researched. In order to avoid the adverse effect of SO2on CO2capture of calcium-based industrial-wastes, the sequential SO2/CO2capture was proposed. The sufation characteristics of the calcium-based industrial wastes after multiple CO2capture cycles were studied.The impurities were added into CaCO3to check their effect on the CO2capacity of calcium-based industrial wastes. The results show that Mn and Cl have great effect on CO2capture of the calcium-based industrial wastes. Mn enhances the CO2capture capacity of CaCO3because it is helpful to keep better microstructure during multiple cycles. The optimum Mn/Ca molar ratio is1:100-1.5:100. When the Cl/Ca molar ratio is greater than0.25:100, Cl aggravates the sintering of CaCO3in the cycles, which leads to the fast decay of the carbonation conversion. Lime mud shows relatively low cyclic CO2capture capacity of the lime mud due to its high Cl content.In view of the adverse effect of Cl on CO2capture, the multiple pre-washing treatments were proposed to decrease the content of Cl in calcium-based industrial wastes. Compared with the original lime mud, the Cl content in the pre-washed lime mud is obviously lower. The CO2capture capacity of the pre-washed lime mud is higher than lime mud. The carbonation conversion of the pre-washed lime mud after100cycles is0.36, and that is1.8times higher than that of lime mud. The prolonged carbonation improves the cyclic CO2capture capacity of calcium-based industrial wastes. The Longer carbonation time and the higher CO2concentration in the prolonged carbonation process are more favorable to improve the CO2capture capacity of calcium-based industrial wastes. The repeated prolonged carbonation treatments in the calcination/carbonation cycles are helpful to keep high CO2capture capacity of the calcium-based industrial wastes. The modification by propionic acid increases the reaction rates and carbonation conversions of calcium-based industrial wastes. For example, the carbonation conversion of the modified carbide slag after30cycles is0.47, which is1.54times greater than that of the untreated carbide slag. The modified calcium-based industrial waste exhibits greater CO2capture capacity than the untreated one. The above three treatment method can improve the microstructure of calcined calcium-based industrial wastes in the cycles. Especially, the pores in the range of10-100nm are dramatically increased. That is the main reason why the modification treatments enhance the CO2capture capacity of calcium-based industrial wastes in multiple the calcination/carbonation cycles.Take carbide slag as one typical representative, the particle attrition characteristics of calcium-based industrial wastes under fluidization condition were investigated. The particles of the carbide slag were continuously attrited in the calcination/carbonation cycles. The attrition rate of particles of the carbide slag decreases with the number of cycles. The calcination temperature has a significant effect on the particle attrition characteristics of the carbide slag. The attrition is more serious under higher calcination temperature. The attrition rate is proportional to the square of the fluidization number. The attrition rate increases rapidly with increasing the fluidization number. Larger particles experience serious attrition. The attrition rate constant (klmp) of the carbide slag is smaller than that of the limestone. It reveals that carbide slag presents better anti attrition characteristics than limestone in the multiple calcination/carbonation cycles.更多还原