计算机与应用化学
計算機與應用化學
계산궤여응용화학
COMPUTERS AND APPLIED CHEMISTRY
2013年
9期
959-962
,共4页
双流体%细网格%曳力%动力学%鼓泡流化床
雙流體%細網格%抴力%動力學%鼓泡流化床
쌍류체%세망격%예력%동역학%고포류화상
two fluid model%fine mesh%drag%hydrodynamics%bubbling fluidized bed
对于A类颗粒，鼓泡流化床中，随着网格尺寸的减小，膨胀高度降低，细网格模拟达到网格无关的值接近于实验数据即网格细化可以预测鼓泡流化床的膨胀高度，但是，当前的计算能力无法达到工业规模反应器的计算要求；流化气速越高，达到网格无关时的网格尺寸越大。与传统的基于平均方法的曳力系数相比，耦合了EMMS/bubbling曳力系数的双流体(TFM)模型允许使用更粗网格，且准确性大大改善，将为工业化大型反应器模拟提供很好的方法，其中，EMMS/bubbling曳力模型如以前的论文(Shi et al.,2011)。
對于A類顆粒，鼓泡流化床中，隨著網格呎吋的減小，膨脹高度降低，細網格模擬達到網格無關的值接近于實驗數據即網格細化可以預測鼓泡流化床的膨脹高度，但是，噹前的計算能力無法達到工業規模反應器的計算要求；流化氣速越高，達到網格無關時的網格呎吋越大。與傳統的基于平均方法的抴力繫數相比，耦閤瞭EMMS/bubbling抴力繫數的雙流體(TFM)模型允許使用更粗網格，且準確性大大改善，將為工業化大型反應器模擬提供很好的方法，其中，EMMS/bubbling抴力模型如以前的論文(Shi et al.,2011)。
대우A류과립，고포류화상중，수착망격척촌적감소，팽창고도강저，세망격모의체도망격무관적치접근우실험수거즉망격세화가이예측고포류화상적팽창고도，단시，당전적계산능력무법체도공업규모반응기적계산요구；류화기속월고，체도망격무관시적망격척촌월대。여전통적기우평균방법적예력계수상비，우합료EMMS/bubbling예력계수적쌍류체(TFM)모형윤허사용경조망격，차준학성대대개선，장위공업화대형반응기모의제공흔호적방법，기중，EMMS/bubbling예력모형여이전적논문(Shi et al.,2011)。
This work analyzed the applicability of using fine-grid simulation of two-fluid model (TFM) for Geldart A particles. First of all, the effect about aspect ratio of mesh was investigated, if grid size was constant and its axial height was varied, the simulation result of aspect ratio 1:2 was in well agreement with one of 1:1, but lower than one of 1:4, which showed the aspect ratio 1:2 and 1:1 are reliable. If mesh area keeps constant, the expansion height was the same but the solids concentration in the center of reactor was varied. Secondly, the grid size was investigated, when the grid size was larger, there were the higher expanding height and more homogeneous solids concentration, where no clear bubbles; when the grid size became smaller, the heterogeneous structure gradually occurs. With the decrease of grid size, the expansion height keeps invariable at the grid size of 0.3mm which is equal to 4.6 particles diameter. Besides, with increasing gas velocity, the expansion height increased and the values of grid size needed for convergence became larger and larger but the deviation between simulation and experiments also grows. At last, the validated results show that, with the decrease of grid size, the expansion height of the fluidized bed lowers and the simulation agrees well with experimental data when converging to its asymptotic solution. But current computation capability hardly meets the requirements for large scale simulations. By comparison, the coarse-grid TFM simulation with EMMS/bubbling drag coefficient which was proposed by Shi et al. (2011) allows using coarser grid than with homogeneous drag coefficient, and its predictions agree reasonably with experimental data. The TFM simulation coupled with bubble-based EMMS (energy-minimization multi-scale) drag model will be a promising method for industrial reactor simulations.
