煅烧石灰石还原脱硫的加压热重实验研究

Sulfidation in a pressurized thermogravimetric analyzer with calcined limestones

在加压热重分析仪上进行了煅烧石灰石与H2S的硫化实验,研究了总压(01～1MPa)、温度(700～950℃)及H2S体积分数(01%～4%)等主要参数对硫化反应的影响.采用扫描电镜及液氮吸附等实验手段分别对反应样品进行了颗粒表观结构和孔隙特性的分析.实验发现在保持H2S体积分数不变的情况下,增加总压,硫化速率增加;而在保持H2S分压不变的情况下,增加压力使得硫化反应速率减小;温度对硫化反应影响很大,随着温度的升高,硫化速率增加;煅烧石灰石与H2S的硫化反应是1级反应.用经典的未反应收缩核模型对气固硫化反应进行了模拟,得到煅烧福建石灰石的化学反应和扩散控制下硫化反应的活化能分别为396和6415kJ/mol.

The sulfidation experiments were conducted in a pressurized thermogravimetric analyzer (PTGA) under calcining conditions. The effects of reaction temperature (700-950°C), total pressure (0.1-1 MPa), and H2S concentration (0.1%-4%) on the sorbent conversions were analyzed. Morphological studies with scanning electron microscope (SEM) were carried out to obtain the pictures of the solid surface to illustrate the changes in particle structure. Nitrogen adsorption measurements were used to determine the physical properties of the samples such as surface area and pore volume. Experimental results show that the sulfidation rate increases with total pressure when the volume fraction of H2S is constant. However, the rate of sulfidation decreases with the increase of total pressure when the H2S partial pressure is constant. Reaction temperature affects the sulfidation greatly, and the reaction rate increases with the increase of temperature. The sulfidation is a first order reaction with respect to H2S partial pressure. The unreacted shrinking core model was applied to determine the parameters of sulfidation. When either chemical reaction or diffusion controls the reaction of H2S with Fujian calcined limestones, the values of the activation energies are measured to be 39.6 or 64.15 kJ/mol, respectively.