原料油汽化特性对催化裂化反应结焦过程影响的CFD模拟

为考察原料油汽化特性影响，在一套百万吨级工业FCC提升管中，基于多相欧拉模型耦合EMMS曳力和传质、油滴汽化和十二集总反应动力学模型，采用三维CFD模拟研究气液固三相流动、汽化、反应、结焦的复杂过程，新开发结焦预测模型定量预测结焦状况，对比研究不同原料油雾化液滴粒径和起始汽化温度下各相和反应组分浓度场、温度场分布和结焦程度。结果表明，模拟方法可较准确预测汽化、反应生焦和结焦过程，不同雾化液滴粒径和起始汽化温度通过流场分布和汽化快慢影响液相油滴汽化率和反应转化率；合适液滴粒径(60 μm)和起始汽化温度(654 K)可提升轻油、汽油、液化石油气目标产品收率并改善结焦程度。

CFD investigation of effects of feedstock oil vaporization on FCC cracking reaction and coking

To investigate the influence of feedstock oil vaporization characteristics, a multi-phase Eulerian model coupling with the models of EMMS drag and mass transfer, oil droplet vaporization and twelve lumped reaction kinetics were used to simulate a million ton scale industrial FCC riser for predicting complex three-phase flow, reaction and coking behaviors. A coking model was proposed to predict the coking extent. The distribution of concentration and temperature of each phase, reaction component and coking extent were investigated under different droplet sizes of atomized feedstock oil and initial vaporization temperatures. The results show that the simulation can well predict the vaporization, reaction coking and fixed coking. The atomized droplet size and initial vaporization temperature affect the oil droplet vaporization rate and cracking reaction conversion rate through the interphase momentum transfer and vaporization speed. Appropriate droplet size (60 μm) and initial vaporization temperature (654 K) can improve the yield of light oil, gasoline and liquefied petroleum gas and alleviate the degree of coking.