双流化床化学链制氢反应器的数值模拟

Numerical simulation of chemical looping hydrogen generation with dual fluidized bed reactors

化学链制氢技术具有能耗低、产氢纯度高、清洁高效等优势,在氢能领域越来越受到重视。化学链制氢系统中复杂的流动与传递过程限制了该技术的发展,需要开展深入的研究工作揭示化学链制氢反应器的运行特性。使用双流体模型对化学链制氢双流化床反应器进行三维数值模拟研究,考察不同操作工况和载氧体属性对系统运行的影响,揭示反应器内部压力和固相浓度分布规律,为双流化床化学链制氢装置的运行和优化提供指导。计算结果表明,随着床料量增加,提升管压力波动幅值减小,运行更加平稳;由于进料口布置形式的影响,在提升管入口段固相分布呈现较强的不对称性;当前工况下提升管入口气速为7 m/s时反应器运行最平稳,随着流化气速增加固体循环量出现剧烈波动。

Chemical looping hydrogen generation technology has the advantages of low energy consumption,high purity of hydrogen production,cleanness and efficiency,etc.,and is receiving more and more attention in the field of hydrogen energy.However,the complex flow and mass transfer mechanisms inherent in the system pose significant challenges to its technological development.Therefore,conducting comprehensive research aimed at elucidating the operational characteristics of the chemical looping hydrogen generation reactor is of significant importance.This study performs a three-dimensional numerical simulation of a dual fluidized bed reactor for chemical looping hydrogen generation utilizing the two-fluid model(TFM)to examine the impacts of various operating conditions and oxygen carrier properties on system performance.The particle quantity and pressure drop in the riser obtained from the simulation agree well with experimental results,which suggests that the current model is capable for the simulation.The numerical results show that increasing the bed material reduces the pressure fluctuation amplitudes in the riser,leading to enhanced operational stability.The distribution of the solid phase in the radial direction of the riser is non-uniform,attributed to the arrangement of the inlet.And non-uniformity distribution of solid becomes more pronounced at higher gas velocities and results in severe operating conditions.Under the current operating conditions,the reactor operates most steadily when the inlet gas velocity of the riser is 7 m/s,and an increase in fluidization gas velocity leads to a significant fluctuation in solid circulation.The flow characteristics of reactor,derived from numerical simulation,provide insights into the operation and optimization of the dual fluidized bed in chemical looping hydrogen generation.