钙基脱除剂对冶炼烟气同时制硫脱硝过程中的氧迁移机理研究

The concentration of SO2 in the smelter off-gas is much higher than that in the flue gas from the power plant. An economical and effective method for simultaneous sulfur recovery and denitrification in the smeter off-gas is a key point to promote the development of nonferrous metals industry. In this project, the mixtures of gypsum ore or desulfuration gypsum and coal after the steam gasification can be used as a kind of removal reagent in simultaneous sulfur recovery and denitrification of the smeter off-gas. The reactivity of the reagent is studied in the reactor to obtain the optimum conditions for the preparation and the reaction. The effects of the microscale factors, including the porosity and the size of the reagent particle, on transition behavior of oxygen element are explored. The dynamic changing of oxygen element both on the surface and interface and in the body of the reagent particle is studied in this project. Some kinetics equations are built when a single gas concentration changed in the thermogravimetric analyzer. Then the intrinsic kinetics equations can be built suitable for the varying concentration of three gases involving O2, SO2 and NO. The effects of the gas-solid two-phase flow behavior on the reactions in the reactor are investigated. Combining with the simulation results from Fluent software, the intrinsic kinetics equations are modified to built a coupling model including the gas-solid two-phase flowing and the reactions.

冶炼厂烟气内SO2浓度远高于火电厂烟气，如何经济有效的对冶炼烟气回收硫资源同时脱硝是推动有色金属行业发展的重点之一。本项目提出了以石膏矿或脱硫石膏与煤粉混合物为原料，经水蒸汽气化后制备脱除剂对冶炼烟气同时制硫脱硝的方法。在反应器内考查颗粒的制硫脱硝活性并优化其制备条件和反应条件，探寻脱除剂孔隙和粒径等微观尺度对氧迁移转化过程的影响机制。研究氧元素在脱除剂颗粒表界面处和体相内化学形态的动态变化行为，构建热分析仪内单一气体组分浓度变化的反应动力学方程，进而建立可适用于O2、SO2和NO三种气体浓度变化的本征反应动力学方程。在反应器内考查气固两相流动对制硫脱硝反应的影响，结合Fluent软件模拟结果，对本征反应动力学方程进行修正，建立反应器内的气固两相流动/氧传递耦合模型。

基于热力学角度，以明确脱除剂类型及反应平衡态下脱硫脱硝效率为目标，系统考察了不同脱除剂/（SO2+NOx）摩尔比下反应起始温度和脱硫脱硝性能，明确了最佳脱除剂类型和剂/（SO2+NOx）摩尔比。以Aspen Plus软件为模拟工具，基于Gibbs自由能最小原理，量化了不同温度条件下化学反应热力学平衡时的产物组成。系统考查了钠、钾、镍、钴和钙等金属所对应硫化物，作为脱除剂的热力学可行性。相关成果发表在化工学报和Journal of CO2 Utilization（2020）上。.从量子理论角度考查了钙基脱除剂与（SO2+NOx）气体的同时反应机制，探寻出了反应中可能的中间体和过渡态IRC的分子结构，并通过多维势能面法预测出反应的路径和反应势垒过程。相关成果发表在高校化学工程学报和Fuel（2019）上。 .在对固定床内脱除剂与高浓度（SO2+NOx）模拟冶炼烟气反应的基础上，提出反应温度与床内空速同时调控反应速率。利用提高反应温度与降低内空速，大幅度提升了脱除剂的同时脱硫脱硝活性。同时将脱除剂制备过程中硫前驱体类型、分散液体积、反应温度等因素耦合，实现脱除剂颗粒的形貌可控，获得了反映活性和稳定性较好的八面体型脱除剂颗粒。研究成果发表在Energy Fuels(2018)和ACS Omega(2020)上，基于化学链循环技术提出的复合型钙基脱硫剂烟气脱硫工艺技术及应用已于2019 年获得3项国家发明专利。