多相流動反應耦合系統(tǒng)的動力學特征分析及

王維

摘 要：針對“多區(qū)協(xié)控”思想下的催化裂化工藝特點，該研究力圖深入認識多相流動反應體系中介尺度結(jié)構(gòu)的形成和影響機制，建立基于結(jié)構(gòu)的描述方法和在流動反應耦合條件下的多尺度模型；在此基礎上，模擬催化裂化的關(guān)鍵過程和區(qū)域，為“多區(qū)協(xié)控”新工藝開發(fā)提供優(yōu)化設計方案和指導。經(jīng)過兩年的研究，取得以下成果：基于上述思路，該研究提出了結(jié)構(gòu)多流體模型，并用以解釋介尺度結(jié)構(gòu)與守恒關(guān)系間的影響，統(tǒng)一了經(jīng)典的雙流體模型以及EMMS模型，為亞網(wǎng)格層次的EMMS曳力與雙流體模型耦合奠定了理論基礎；該理論形成的EMMS亞網(wǎng)格曳力，經(jīng)過簡化的力平衡關(guān)系，已用于分析非均勻廣義流化系統(tǒng)中的各種流動穩(wěn)定性問題，完成了主要工業(yè)操作單元（包括預提升段、主提升段、再生器、旋風分離器等）涉及的廣義流化分析和多區(qū)相圖，分析影響各區(qū)流動的穩(wěn)定性條件；該理論與CFD模擬結(jié)合，已應用于模擬提升管入口段的流動混合情況，捕捉到了理論預測的二次流現(xiàn)象；完成了提升管進料段氣固兩相流動及催化裂化汽提段內(nèi)氣固流動特性的模擬初步研究；初步分析了不同進料角度對兩相流動，特別是二次流的影響，模擬結(jié)果與實驗符合較好；為優(yōu)化入口設計提供了依據(jù)；該理論還用于提升段的反應過程分析，模擬結(jié)果與現(xiàn)有的工業(yè)數(shù)據(jù)較為吻合，取得了較好的效果?？傊?，在FCC多區(qū)協(xié)控強化的理論基礎上，這一研究工作，深化了兩相流模擬與分析的方法基礎，并在應用中解決了實際問題。

關(guān)鍵詞：流態(tài)化 計算流體力學 模擬 多尺度 流化催化裂化

Abstract：In line with the idea of “coordination between multiple zones” for fluid catalytic cracking （FCC）， this research is to investigate the mechanism of meso-scale structure and its effects on the multiphase reactive flow systems and thereby establish a set of structure-dependent methods for multiscale modeling of reactive flow systesm. The proposed model thereon will be applied to simulate key processes and areas in FCC reactor and then help optimal design of novel processes. Several achievements have been obtained as follows： The structure-dependent multi-fluid model （SFM） was proposed to describe the interrelationship between meso-scale structure and conservation laws. The SFM was found to unify the classic two-fluid model （TFM） and the energy minimization multiscale （EMMS） model with different structures. That paves the solid base for why we can use the EMMS drag model at sub-grid level for the homogeneous TFM because the TFM is actually the filtered or averaged description of the SFM at each grid. The sub-grid EMMS drag was used in a simplified force balance equation to analyze different kinds of aggregative fluidized systems and the stability issues therein. A generalized fluidization diagram with consideration of meso-scale structure was drawn for the reactor units involved such as riser， regenerator and separator and so on. The SFM was integrated into CFD for simulation of the mixing phenomena in inlet area of a riser. The secondary flow phenomenon was captured successfully that coincides with theoretical analysis. Simulation of stripper area was also performed. The effects of inlet angle and configuration on the two phase flow， in particular， the secondary flow， were studied extensively. These work provide basis for optimization of inlet configuration of riser. The multiscale model has been also applied in reactive flow simulation of FCC reactor. The results show good agreement with industrial data available. In summary， on the basis of the theory of “coordination between multiple zones” for FCC， this work paves physical basis of relevant two-phase flow study and it has been validated by solving industrial problems.

Key Words：Fluidization；CFD；Simulation；Multiscale；FCC

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