【作者】 张海波；

【导师】 蔡伟民；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2008， 硕士

【摘要】 本论文对国内外烟气脱硫工艺进行了综述,认识到多孔材料(如活性炭、活性焦、沸石)吸附脱硫技术具有用水少或不用水、二次污染少、能回收硫资源、反应温度相对较低、具有连续再生能力等,具有很好的竞争能力和发展前景,适于在我国推广应用。目前,文献报道的以多孔材料作为脱硫剂的研究主要集中在活性炭和活性焦上,对于沸石脱除二氧化硫气体的研究仍处于起步阶段。经筛选实验,本论文选用5A沸石为脱硫剂,以其对低浓度二氧化硫(<0.4%)的吸附行为为研究对象,系统研究了吸附温度、SO2浓度、气体流量、吸附剂量和吸附剂含水量等因素对5A沸石吸附性能的影响,并对5A沸石固定床的吸附过程进行了吸附动力学研究。实验发现,100℃以下,5A沸石的吸附脱硫性能随着温度升高而下降;当温度高于100℃时,5A沸石的吸附性能较差,并且吸附量和脱硫效率不再随温度有明显变化。SO2浓度越高,气体通过5A沸石吸附柱的流速越大,吸附效率越低。适当增加吸附剂量(>20%),能显著延长吸附时间。沸石孔道中的水分与SO2相互干扰,存在竞争吸附,使沸石的脱硫性能显著降低。计算表明,5A沸石固定床的传质区长度基本上在2.5~5.0cm。温度越低,传质区长度越短,沸石固定床层利用率越高。较大的气体流量和吸附剂量,有利于降低传质区长度。80℃下5A沸石吸附低浓度SO2的吸附等温线,属于优惠型吸附等温线。通过线性拟合,分别得到该温度下5A沸石吸附二氧化硫的Freundlich和Langmuir吸附等温式。吸附动力学研究表明,SO2在5A沸石上的吸附过程大致可分为三个阶段。第一阶段为等速过程,第二阶段为减速过程,第三阶段也为等速过程。吸附速率在初期基本保持等速,在第二阶段迅速下降,且与时间和吸附量接近线性关系。根据班厄姆公式,计算得到了80℃和90℃下,5A沸石对低浓度SO2的吸附速率公式。更多还原

【Abstract】 Based on the review of the technologies of FGD, it is derived that porous adsorbent (such as active carbon/coke, zeolites) FGD technology is a very promising one in the future because of its characteristics as follows: simple process and easy control, lower or no water consumption, low secondary pollution, recovery of sulfur or other sulfur-containing products, relatively lower reaction temperature, ability for the regeneration and so on.Reviewing recent works about porous absorbent reported in open literature, a limited number of studies have been carried out on the adsorption of SO2 over zeolites while most researches focus on active carbon/coke technology. In this paper, we did researches of 5A zeolites adsorption ability under low sulfur dioxide concentration (<0.4%). The influence of adsorption temperature, SO2 inlet concentration, gas velocity, amount of absorbent and H2O in zeolites has been systematically studied by using 5A zeolites as adsorbent. Meanwhile, the adsorption pattern of 5A zeolite fixed bed has been studied, and adsorption kinetics study has been conducted on adsorption process over 5A zeolites.The result indicates that adsorption capacity and desulfurization efficient of 5A zeolites get lower when temperature increases under 100℃. Above 100℃, the adsorption performance of 5A zeolites was not satisfied and there is almost no connection between temperature and desulphurization activity. The desulfurization efficient is lower in the condition of higher inlet SO2 concentration and higher gas velocity. An appropriate increase (>20%) in the amount of adsorbent results in marginal improvement of adsorption efficiency. The presence of water in zeolite pores reduces its SO2 capacity, and there exists competitive adsorption over zeolites between H2O and SO2. Mass transfer zone of 5A zeolites is 2.5~5.0cm long. At lower temperature, the length of mass transfer zone is shorter and the fixed bed of zeolites behaviors more efficiently. Higher gas velocity and more absorbent help increase the length of mass transfer zone.At 80℃, the adsorption isotherm of 5A zeolites is favorable type, and the corresponding Freundlich and Langmuir adsorption isotherm formulas are obtained, respectively. The adsorption kinetics study indicates that the adsorption process of sulfur dioxide over 5A zeolites approximately undergoes three stages: adsorption velocity constant stage, adsorption velocity decrease stage and another adsorption velocity constant stage. At first, the adsorption velocity is almost constant, and then reduces rapidly. The adsorption velocity almost fit linear with time/adsorption capacity. On the base of Banham formula, we obtained the adsorption velocity formula of 5A zeolites at the temperatures of 80℃and 90℃.更多还原