Particle coating process, one of the main methods to improve the particle properties, is widely used in industrial production and pharmaceutical industry. For the scale up and optimization of this process, a mechanistic and detailed study is needed or numerical simulation as an alternative way. Decomposition of substances usually involves multiple chemical reactions and produces multiple substances in the actual chemical reaction. In the study, a chemical reaction flow (CRF) model has been established based on kinetic mechanism of elementary reaction, the theory of molecular thermodynamics and the sweep theory. It was established with the comprehensive consideration of the decomposition of substances, deposition process, adhesion process, desorption process, hydrogen inhibition, and clearance effect. Then the CFD-DEM model was coupled with CRF model to simulate particle coating process by FB-CVD method, and the CFD-DEM-CRF coupling model was implemented in the software Fluent-EDEM with their user definition function (UDF) and application programming interface (API). The coating process in the spouted bed was analyzed in detail and the coating behavior under different conditions were compared at the aspects of CVD rate, coating efficiency, particle concentration distribution, particle mixing index and gas concentration distribution. It is found that the average CVD rate is 6.06 × 10 −4 mg/s when the inlet gas velocity is 11 m/s and bed temperature is 1273 K, and simulation result agrees with the experimental result well. Average CVD rate and coating efficiency increase with temperature increasing, but decrease acutely with mass fraction of injected hydrogen increasing. The CFD-DEM-CRF coupling model can be developed as a basic model for investigating particle coating process in detail and depth and can provide some guidance for the operating conditions and parameters design of the spouted bed in the real coating process.

中文翻译：

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结合化学反应流模型的颗粒包覆过程的CFD-DEM模拟

颗粒涂覆工艺是改善颗粒性能的主要方法之一，已广泛用于工业生产和制药工业。为了扩大规模并优化此过程，需要进行详细的机械研究或将数值模拟作为替代方法。物质分解通常涉及多个化学反应，并且在实际化学反应中会产生多种物质。在研究中，基于基本反应的动力学机理，分子热力学理论和波及理论，建立了化学反应流（CRF）模型。建立该模型时要综合考虑物质的分解，沉积过程，附着过程，解吸过程，氢抑制和清除效果。然后将CFD-DEM模型与CRF模型耦合，通过FB-CVD方法模拟颗粒涂覆过程，并在Fluent-EDEM软件中利用其用户定义功能（UDF）和应用编程来实现CFD-DEM-CRF耦合模型。接口（API）。详细分析了喷射床中的涂层过程，从CVD速率，涂层效率，颗粒浓度分布，颗粒混合指数和气体浓度分布等方面对不同条件下的涂层行为进行了比较。结果表明，当进气速度为11 m / s，床温为1273 K时，平均CVD速率为6.06×10 -4 mg / s，模拟结果与实验结果吻合良好。平均CVD速率和涂层效率随温度的升高而增加，但随着注入氢质量分数的增加而急剧下降。CFD-DEM-CRF耦合模型可以作为研究颗粒包衣过程的细节和深度的基础模型而开发，并可以为实际包衣过程中喷动床的操作条件和参数设计提供一些指导。