氧燃烧方式下石灰石直接固硫反应模拟

氧燃烧方式下高浓度CO2气氛使得石灰石与SO2的气固反应存在直接固硫和间接固硫两种方式。在热重分析仪上进行了石灰石直接硫化的实验,考察了温度、SO2浓度对直接固硫反应的影响。基于球形颗粒气体扩散理论,在未反应收缩核模型的基础上推导出一种从实验数据计算化学反应速率常数和SO2反应级数的新方法。同时在已有研究的基础上改进了产物层扩散系数的计算方法,并采用未反应收缩核模型对不同温度、SO2浓度条件下石灰石直接固硫反应进行模拟,模拟结果与实验结果较为吻合。在所建立模型的基础上定性讨论了温度、孔隙率、平均孔径对产物层有效扩散系数的影响,发现温度对有效扩散系数影响很显著,而孔隙率、平均孔径的影响较小。

Simulation of direct sulfation of limestone in oxy-fuel combustion

There exist two reaction modes, direct and indirect, for the gas-solid desulphurization reaction between limestone and SO₂ at high CO₂ concentration from oxy-fuel combustion.The effect of temperature and SO2 concentration on direct desulphurization was studied with TGA.Based on spherical particle gas diffusion theory, a new method for calculating reaction rate constant and reaction order of SO₂ utilizing shrinking unreacted core （SUC）model was proposed.Meanwhile, the method for calculating diffusion coefficient of SO₂ through products layer was improved.Furthermore, simulation was carried out using SUC model for the direct desulphurization by limestone at various temperature and SO₂ concentration, and the agreement between simulation results and experiment data was good.At last, the effect of temperature, porosity and average pore radius on effectiveness diffusion coefficient are discussed qualitatively based on the model proposed in the paper, and it is found that the effect of temperature is significant but the effects of porosity and average pore radius are comparatively minor.