循环流化床甲烷化反应器中体积缩小反应与流动和传质的内在耦合机制

合成气甲烷化工艺是生物质气化制备天然气技术的关键环节之一，循环流化床由于其优异的传热传质性能有望成为潜在的甲烷化反应器。甲烷化反应是一个摩尔数减小反应，揭示循环流化床甲烷化反应器中的体积缩小反应与流动和传递间的匹配关系，是优化反应器运行和指导反应器放大过程中需要解决的关键问题。本课题拟以体积缩小反应对流化特性的影响为出发点，采用热态实验和数值计算相结合的方式对循环流化床甲烷化反应器进行研究：通过热态实验研究循环流化床甲烷化反应中不同操作参数下的反应转化特性，借助多相流测试手段明晰体积缩小反应对床内流动结构的影响，并依靠数值计算“多尺度可视化”特点，从颗粒聚团和反应器两个尺度层面分析反应器中的化学反应、流动和传质现象，进而获得三者间的内在耦合机制。本课题的研究将为循环流化床甲烷化反应器的优化与放大提供一定的理论基础。

Methanation of the syngas from biomass gasification is one of the key processes in the biomass-to-SNG technology. Circulating fluidized bed reactor turns to be suitable for the operation of methanation reaction with high exothermicity. The methanation reaction involves a reduction in the gas volumetric flow. Thus an exploration of the relationship between the reaction, hydrodynamics and mass transfer in the circulating fluidized bed reactor is very important for optimizing and scale-up of the reactor. In this research, experiments and simulations are both chosen for the study. And the investigation of the effect of reaction with a reduction in the gas volume on the fluidization characteristics in the circulating fluidized bed reactor is considered as the basis to decoupling the aforementioned relationship. The conversion and selectivity in the circulating fluidized bed reactor under different operating conditions will be tested in a lab-scale circulating fluidized bed methanation reactor, and the effect of methanation reaction on the two-phase hydrodynamics in the bed will also be monitored by several measuring techniques. Together with the ‘multi-scale visualization’ simulation results, reaction、hydrodynamics and mass transfer can be separately analyzed from both cluster scale and reactor scale. Accordingly, the aforementioned relationship can be properly achieved. This research can provide a theoretical basis for the optimization and scale up of methanation circulating fluidized bed reactor.