Fundamental Study and Reactor Development on Absorption and Desorption of Carbon Dioxide Using High Thmperature Molten Salt Slurry

本论文在2007 - 2008年进行了硅酸锂细颗粒悬浮于碳酸锂钾熔融液中的循环浆态鼓泡塔对CO2吸收和解吸的基础性研究，主要内容如下：1. CO_2气泡在熔盐浆料中的溶解和剥离行为分析在热反应器中制备了硅酸锂微粒和熔融碳酸锂钾。以CO_2含量为20%、N_2含量为80%的模拟烟气作为反应器的进料。通过测定反应器中CO2的质量平衡，观察了硅酸锂质量和熔盐组成变化时反应器中CO2的吸收情况。通过测定反应器排出气体中CO_2浓度的时间历程，测定了CO_2在熔盐中的最大吸收速率和溶解度。考察了进气流量、熔盐组成和料浆浓度对气泡行为的影响，并考察了反应器升温至脱附温度时CO2的汽提行为。讨论了硅酸锂用量、温度和升温速率对CO_2反萃率的影响。在本研究中，CO_2在熔盐中的分子转移是限制性过程，即CO_2从气泡中的溶解控制了整个反应速率.循环浆态鼓泡塔内流体力学实验模拟了常温下高温反应器内的气液固流体力学，采用冷态模型。用1微米PVC颗粒代替硅酸锂颗粒，用表面活性剂水溶液作为熔盐模拟液。在自行设计的循环浆态鼓泡塔中，对气含率和循环液速进行了实验研究，为工业应用提供了基础资料。

The study has been done for 2007-2008 to obtain the fundamental data in terms of the absorption and desorption of carbon dioxide using a circulating slurry bubble column in which lithium silicate fine particles are suspended in molten lithium-potassium carbonate at high temperature.That was summarized as follows :1. Analysis of dissolution and stripping behavior of CO_2 bubble into molten salt slurryThe lithium silicate fine particles and molten Li-K-carbonate were prepared in the hot reactor. The model flue gas which has 20% CO_2 and 80% N_2 was fed into the reactor. The absorbed CO_2 was observed by measuring mass balance of CO_2 in the reactor when the mass of lithium silicate and the composition of molten salt were changed. Maximum absorption rate and solubility of CO_2 in molten salt were measured by the time course of CO_2 concentration in effluent gas from the reactor. The effects of influent gas flow rate, composition in molten salt and slurry concentration on gas bubble behavior were investigated.On the other hand, the stripping behavior of CO_2 was investigated when the reactor was heated up to the desorption temperature. The effects of the mass of lithium silicate, temperature and heating rate on the stripping rate of CO_2 were discussed. In this study, the limited process was the CO_2 molecular transfer in the molten salt, that is, CO_2 dissolution from bubbles governed the overall reaction rate.2. Hydrodynamics in circulating slurry bubble columnTo experimentally simulate the gas-liquid-solid hydrodynamics in high temperature reactor under the room temperature, the cold model was used. The 1 micron PVC particles was used as instead of lithium silicate particles and the surfactant aqueous solution was used as a imitation liquid of molten salt. By using a designed circulating slurry bubble column, the gas holdup and the circulation rate of liquid were investigated to know the fundamental information to apply for industry.