【作者】 何杰；

【导师】 张卫江；

【作者基本信息】 天津大学 ， 化学工程， 2012， 博士

【摘要】 目前湿法脱硫是烟气脱硫技术中最主要的工艺,为了挖掘湿式脱硫技术的潜能,研究提高脱硫效率和和脱硫的稳定性,本课题对气液并流脱硫的流体力学性能、改良的浆液脱硫工艺以及室温离子液体脱硫工艺等方面进行了深入研究,力求综合、全面的总结湿法脱硫工艺,主要研究内容如下:本课题对气液并流向下吸收SO₂的流体力学特性进行了系统的研究,研究内容主要包括脱硫并流规整填料和散堆填料塔的流型研究、液体喷淋密度对全塔压降的影响、气相动能因子对并流压降的影响、脱硫并流散堆填料塔的持液量的研究、液气比对并流脱硫效率的影响、气相动能因子对脱硫效率的影响以及喷射流区域内气液并流吸收SO₂的传质系数。为了改善浆液脱硫工艺的传质性能,课题重点讨论了进气流速、液气比、进气SO₂的浓度以及pH等因素对浆液脱硫效率的影响,并研究无机添加剂、有机添加剂以及复合型添加剂对石灰石的促溶作用,以及添加了脱硫添加剂后浆液的脱硫性能。研究发现,脱硫率与气速的函数关系存在着最值;进口气体中SO₂的浓度和浆液pH值与所需的最小液气比呈反比关系,且最适宜的pH值范围在5-6之间;添加剂对脱硫率的影响按下列顺序依次减弱:己二酸+NaCl的复合添加剂、己二酸有机添加剂、NaCl+己二酸的复合添加剂、无机添加剂NaCl,而且添加剂的添加量存在着最值。同时,为了深入研究浆液吸收SO₂的增强效应,本课题应用膜理论来描述SO₂吸收中液相的传递过程,研究发现溶解的钙离子浓度与SO₂的进口分压存在着正函数关系,而石灰石的初始溶度对钙离子浓度的影响相对比较微弱;SO₂的吸收速率与SO₂的进口分压基本上呈线性关系,而石灰石的初始溶度对SO₂吸收速率的影响相对比较微弱;溶解的钙离子浓度越大、石灰石的粒径越小越有助于增大增强因子;总亚硫酸盐浓度越小越有助于增大增强因子,且浓度越小增强效应越明显。研究表明,离子溶液四甲基胍乳酸盐作为综合性能优良的脱硫剂是一种具有潜力的传统吸收剂的替代品,而且该离子液体重复利用率高,溶剂损耗小,可以连续循环进行吸收-解吸SO₂的实验。应用Flory-Huggins模型能很好的描述SO₂-[C6MIm][Tf2N]体系的气液平衡关系,此理论在一定程度上可以证明SO₂-ILs体系的溶解性归根结底是由熵效应引起的。更多还原

【Abstract】 Flue gas desulfuration by wet processes has been one of the most important techniques by now. Further researches have been made in this work to investigate the fluid dynamic performance of cocurrent gas-water desulfuration operation, the improved desulfuration process by limestone slurry and the absorption behavior of SO₂ in ionic liquids. All the efforts are made to develop the potential in increasing the efficiency and stability of SO₂ removal and to give a full summary on the wet flue gas desulfuration. The main contents are described as follows.Fluid dynamic properties of SO₂ absorption by using upflow gas-water cocurrent in a packed column have been systematically studied, including the flow-regime and holdup of cocurrent desulfuration in a structured and random packed column, the effect of liquid spray density on the total pressure drop, the effect of gas phase loading factor on the pressure drop, the effects of liquid-gas ratio and gas phase loading factor on the efficiency of SO₂ removal and the mass transfer coefficients for SO₂ cocurrent absorption in the region of jet flow.The effects of velocity of inlet gas, liquid-gas ratio, SO₂ concentration of inlet gas and pH value on the limestone slurry desulfuration were investigated to improve the mass transfer performance. In addition, the investigation of inorganic additives, organic additives and composite additives on enhancing the dissolution of limestone as well as the SO₂ removal performance by the limestone with the addition of the additives were also carried out. It can be stated that a maximum value can be found for the relation between SO₂ removal efficiency and gas velocity. The concentration of SO₂ in inlet gas and the pH value of the limestone slurry are in inverse proportion to minimum liquid-gas ratio with the most suitable range of pH of 5-6. The effects of the additives on the efficiency of SO₂ removal are in the order of adipate+NaCl > adipate > NaCl+adipate > NaCl, and a maximum value for the additive amount of the additives can be observed. Meanwhile, liquid phase mass transfer process has been described using film theory to further investigate the enhancing effect of limestone absorption SO₂. It can be seen that a positive correlation exists between the dissolved Ca2+ concentration and the SO₂ inlet partial pressure, while the effect of initial limestone concentration on the Ca2+ concentration can be neglected. SO₂ absorption rate is basically linear with SO₂ inlet partial pressure, whereas the effect of initial limestone concentration on SO₂ absorption rate can be neglected. The enhancing factor increases with the increase of the dissolved Ca2+ concentration and the decrease of the limestone particle size and the total sulfite concentration. The enhancing effect is more obvious with the less concentration of sulfite.The results indicate that 1,1,3,3-tetramethylguanidium lactate, as a desulfurizing agent with an excellent performance, can be used as a substitute for the traditional absorbents, and this ionic liquid with a high recycling rate and a low loss rate can be used to carry out SO₂ absorption-desorption experiment continuously. The vapor liquid equilibrium relationship of SO₂-[C6MIm][Tf2N] system can be well described by the Flory-Huggins model, which can prove to certain degree that dissolving action of SO₂-ILs systems is caused by entropy effect更多还原