Three-dimensional modelling of the multiphase hydrodynamics in a separated-gasification chemical looping combustion unit during full-loop operation
Three-dimensional modelling of the multiphase hydrodynamics in a separated-gasification chemical looping combustion unit during full-loop operation
复制标题
分离气化化学循环燃烧装置全循环运行过程中多相流体动力学的三维建模
DOI：
10.1016/j.jclepro.2020.122782
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发表时间：
2020
影响因子：
11.1
通讯作者：
Baosheng Jin
中科院分区：
文献类型：
--
作者：
Xudong Wang;Xiaojia Wang;Yali Shao;Baosheng Jin
分离气化化学循环燃烧(SG-CLC)是一种化石燃料的清洁利用技术，它可以在高效燃烧过程中分离出二氧化碳，氧载体降解率低，零能量惩罚。作为多相流体力学优化的一个重要组成部分，本文对该装置的多相流体动力学进行了建模和预测。该装置由气化炉(GR)、还原反应器(RR)和空气反应器(AR)组成。为了深入了解气相、载氧相和砂相三相的流动行为，首次建立了SG-CLC体系的三维计算流体力学模型。其主要目的是预测该SG-CLC系统燃料侧的多相流体动力学，因为它对燃烧效率有重要影响。通过实验数据对CFD模型预测的轴向压力分布进行了验证，验证了其可行性。在此模型的基础上，研究了基本条件下燃料侧不同相(GR和RR)的流体动力学，揭示了循环建立过程中的气固两相流动机理。此外，考察了操作条件对流体力学性质的影响。将RR的局部气固滑移速度拟合为表观流态化数和轴向位置的函数，对该系统的预测具有较高的精度。
Separated-gasification chemical looping combustion (SG-CLC) is a clean utilization technology for fossil fuels, which can separate CO2during high-performance combustion process with low degradation of oxygen carrier and zero-energy penalty. As an important part of the optimization, modelling and prediction of the multiphase hydrodynamics in the SG-CLC unit were conducted in this work. This unit consists of a gasifier (GR), a reduction reactor (RR) and an air reactor (AR). For thorough understanding of the flow behaviors of three phases (gas, oxygen carrier and sand phases), a three-dimensional computational fluid dynamics (CFD) model for SG-CLC system was first implemented. The main purpose is to predict multiphase hydrodynamics at the fuel side of this SG-CLC system due to its significant effects on combustion efficiency. The axial pressure profile predicted by the CFD model was validated by experimental data to demonstrate its feasibility. Then, based on this model, the hydrodynamics of different phases at fuel side (GR and RR) were investigated under fundamental condition, which indicated the gas-solid flow mechanism in circulation establishment process. Furthermore, effects of the operation condition on the hydrodynamics properties were investigated. The local gas-solid slip velocity in RR was fitted as the function of superficial fluidizing numberNrand axial position, which showed high accuracy for the prediction in this system.