FCC提升管反应器中终止剂注入对裂化反应的影响

通过对催化裂化提升管注入终止剂前后的工况进行数值模拟,研究了终止剂注入对提升管内速度分布、催化剂颗粒浓度分布、温度分布以及组分浓度分布的影响,考察了不同注入量以及注入高度的终止剂在提升管内的作用区域及其对裂化反应的影响。研究表明,终止剂的注入大幅提升了提升管内的油气速度,降低了催化剂浓度、油气和催化剂的温度,使得提升管内原料的裂化程度降低,二次反应减少。且不同注入量和注入高度的作用区域不同,对裂化反应的影响不同,应根据实际工况进行分析。     

浅议反应终止剂技术的应用

终止剂技术是一种通过单独控制提升管反应器底部的油剂混合温度和出口的反应温度,改进提升管的温度分布状态,从而达到优化提升管反应产物分布的重要技术,其中实施终止剂技术的关键问题是终止剂的选用与注入量的选择。本文结合垦利石化总厂新投产的45×104t/a重油催化裂化装置的一些实际生产资料数据,分析了以蒸汽冷凝水为终止剂的优越性熏并结合该厂生产情况总结出了终止剂注入量对反应产物分布的影响。     

FCC提升管反应器中颗粒聚团对裂化反应的影响

在对气固流动体系颗粒聚团实验现象分析的基础上,以减压馏分油裂化反应为例,对反应器中最常见的球形和椭球形聚团上的流动、传热和反应过程进行了模拟计算,得到了聚团内外油气和催化剂颗粒的速度分布、温度分布、浓度分布以及反应速率分布。研究结果表明,催化剂颗粒聚团的存在阻碍了油气与催化剂颗粒的充分接触,进而造成系统内速度和温度的不均匀分布,影响了裂化反应的发生,使得有颗粒聚团时的一次反应速率明显低于无聚团时的反应速率,颗粒聚团显著影响了油气在颗粒上的反应时间,最终导致气体和焦炭产率升高,对裂化反应产品收率分布十分不利。     

渣油催化裂化提升管反应器组成分布的数值模拟

在流动模型和集总反应动力学模型的基础上,将流动、传热、反应综合考虑,建立了渣油催化裂化提升管反应器的数学模型,通过对4套不同工况进行数值模拟,考察了反应器内气相组成分布和催化剂颗粒的温度、速度分布,得到了与工业装置基本一致的提升管出口参数,从而验证了模型的可靠性.     

渣油催化裂化提升管反应器性能的数值模拟--喷嘴射流速度与角度对流动反应的影响

应用三维数值模拟的研究方法,考察了喷嘴射流速度与角度对提升管反应器内流动、传热及反应的影响。从数值模拟结果来看,同一角度下、一定范围内的射流速度对提升管内流动形态改变不大,对催化剂和油气浓度分布、气相组成浓度分布有一定影响,而角度变化对流动、反应都有较大影响,从本研究的范围来看,可以得出对不同的操作条件和装置存在最优喷嘴射流速度和角度的结论,射流角度应不超过45°,且45°时60m·s~(-1)的射流速度为优。     

渣油催化裂化提升管反应器性能的数值模拟——喷嘴射流速度与角度对流动反应的影响

应用三维数值模拟的研究方法,考察了喷嘴射流速度与角度对提升管反应器内流动、传热及反应的影响。从数值模拟结果来看,同一角度下、一定范围内的射流速度对提升管内流动形态改变不大,对催化剂和油气浓度分布、气相组成浓度分布有一定影响,而角度变化对流动、反应都有较大影响,从本研究的范围来看,可以得出对不同的操作条件和装置存在最优喷嘴射流速度和角度的结论,射流角度应不超过45°,且45°时60m·s~(-1)的射流速度为优。     

TiCl_4催化体系制备丁基橡胶

研究了TiCl4作为主引发剂,引发异丁烯的本体均聚和异丁烯与异戊二烯共聚的反应规律。考察了不同催化剂浓度、温度以及是否加入终止剂终止反应,对聚合反应的影响。结果表明,降低温度对产率和催化剂效率都有提高;而随着催化剂浓度增大、产率提高,但催化剂效率出现先升后降的趋势。另外,未加入终止剂时,异丁烯的均聚会出现大量双键,影响共聚时不饱和度的计算。     

FCC沉降器粗旋工作性能的数值模拟

引言 催化裂化工艺(fluidized catalytic cracking, FCC)是目前我国重质油轻质化加工的主要方法之一.重质油裂化反应过程主要在提升管反应器内完成,提升管出口通常设置旋风分离器(简称粗旋)将反应后油气与催化剂快速分离,以避免发生过裂化反应.粗旋工作性能的优劣直接影响装置目的产物的收率、沉降器内部结焦以及油浆固含量.     

入口结构对18 m气固循环流化床提升管内颗粒流动特性的影响

在高18 m、内径80 mm的循环流化床提升管内分别考察了三种入口结构对颗粒流动特性的影响。实验结果表明：入口结构主要影响提升管底部区域的颗粒流动特性,不同入口结构对颗粒流动影响不同。相同操作条件下,当采用多管式入口结构时,径向上提升管底部区域的颗粒浓度分布相对均匀,轴向上颗粒能够迅速达到充分发展状态,充分发展高度在9 m左右;当采用多孔板入口结构时,径向上提升管底部颗粒浓度差别较大,轴向上颗粒发展较慢,需要更高高度才能达到充分发展,充分发展高度约为11 m;当采用单管式入口结构时,径向上颗粒浓度分布和轴向上颗粒充分发展速度均处于前两者之间,底部颗粒浓度径向分布仍为中间稀、边壁浓的不均匀分布,颗粒浓度轴向充分发展高度约为10 m。     

稠密气体理论在催化裂化提升管中的应用

运用已建立的颗粒动力学模型并耦合催化裂化反应的十三集总动力学模型，建立了催化裂提升管反应器内反应油气和催化剂颗粒的传质，反应的数学模，结合工业提升管的操作参数，模拟预测了速度场，温度场和组分分布。     

CFD analysis of hydrodynamic, heat transfer and reaction of three phase riser reactor

Catalytic cracking reaction and vaporization of gas oil droplets have significant effects on the gas solid mixture hydrodynamic and heat transfer phenomena in a fluid catalytic cracking (FCC) riser reactor. A three-dimensional computational fluid dynamic (CFD) model of the reactor has been developed considering three phase hydrodynamics, cracking reactions, heat and mass transfer as well as evaporation of the feed droplets into a gas solid flow. A hybrid Eulerian-Lagrangian method was applied to numerically simulate the vaporization of gas oil droplets and catalytic reactions in the gas-solid fluidized bed. The distributions of volume fraction of each phase, gas and catalyst velocities, gas and particle temperatures as well as gas oil vapor species were computed assuming six lump kinetic reactions in the gas phase. The developed model is capable of predicting coke formation and its effect on catalyst activity reduction. In this research, the catalyst deactivation coefficient was modeled as a function of catalyst particle residence time, in order to investigate the effects of catalyst deactivation on gas oil and gasoline concentrations along the reactor length. The simulation results showed that droplet vaporization and catalytic cracking reactions drastically impact riser hydrodynamics and heat transfer.     

Modeling of vaporization and cracking of liquid oil injected in a gas-solid riser

Vaporization and cracking of liquid oil injected in a gas-solid riser (fluid catalytic cracking riser reactor) was computationally studied in this work. Evaporation of a single drop injected in a stream of gas-solid mixture was analyzed first. A model for simulating evaporation of a drop considering heat transfer from the gas phase as well as from the solid particles was developed. The model relates the evaporation rate of droplet with rate of collisions of solid particles, specific heat capacities of solid and liquid, latent heat of vaporization, relative velocity of gas and liquid and temperatures of three phases. The understanding gained from such a model was then extended to simulate evaporation of liquid drops injected in FCC risers. The Eulerian-Lagrangian approach was used to simulate simultaneous evaporation and cracking reactions occurring in FCC riser reactors. A commercial CFD code, FLUENT (of Fluent Inc., USA) was used. Four and ten lump models were used for simulating cracking reactions. Appropriate user defined functions were developed to implement heterogeneous kinetics and heat transfer models in FLUENT. A special algorithm was developed to calculate accumulated coke on catalyst particles. A boiling point range was considered for simulating realistic oil feedstock. The model was first evaluated by comparing predicted results with published industrial data. The simulations were then carried out to understand influence of key design and operating parameters on performance of FCC riser reactors. The parameters studied included; initial oil droplet distribution, catalyst inlet temperature, catalyst to oil ratio and thermal cracking. The approach, model and results presented here would be useful for optimization of FCC operation, cost to benefit analysis of new FCC nozzles and related decision-making.     

催化裂化提升管反应器中颗粒聚团裂化反应的数值模拟

Behavior of catalytic cracking reactions of particle cluster in fluid catalytic cracking (FCC) riser reactors was numerically analyzed using a four-lump mathematical model. Effects of the cluster porosity, inlet gas velocity and temperature, and coke deposition on cracking reactions of the cluster were investigated. Distributions of temperature, gases, and gasoline from both catalyst particle cluster and an isolated catalyst particle are presented. The reaction rates from vacuum gas oil (VGO) to gasoline, gas and coke of individual particle in the cluster are higher than those of the isolated particle, but it reverses for the reaction rates from gasoline to gas and coke. Less gasoline is produced by particle clustering. Simulated results show that the produced mass fluxes of gas and gasoline increase with the operating temperature and molar concentration of VGO, and decrease due to the formation of coke.     

提升管反应器进料混合段内气固两相流动特性(Ⅰ)实验研究

根据实际工业的操作条件 ,采用催化裂化催化剂及空气 ,在大型冷模实验装置上对催化裂化提升管进料混合段内射流相与颗粒相的速度场、浓度场进行了系统测试 .结果表明 ,由于旋涡场的诱导作用 ,喷嘴射流注入到提升管中以后将会产生二次流动 ,二次流先是发展扩大 ,随后又与主流逐渐汇合 .根据混合流场的分布特点 ,可以将这一极其复杂的流场由下到上分为上游影响区段、主射流影响区段、二次流影响区段、混合发展区段 4部分 ,各区段在径向上又可再分为 2或 3个区来表征有关参数的分布特点     

Numerical Simulation on Gas-Solid Two-Phase Turbulent Flow in FCC Riser Reactors(Ⅱ) Numerical Simulation on the Gas-Solid Two-Phase Turbulent Flow

Numerical simulation on the flow,heat transfer and cracking reactions in commercial fluid catalyticcracking(FCC)riser reactors were carried out employing the developed turbulent gas-solid two-phase flow-reac-tion model for FCC riser reactors given in Part Ⅰ of the present paper.Detailed information about the turbulentflow fields in the riser reactor obtained revealed the basic characteristics of the gas-solid two-phase turbulentflows when heat transfer and catalytic cracking reactions were co-existing in the riser.Results showed that thedistributions of the flow,the turbulence kinetic energy and the catalyst particle concentration are not uniform inthe axial,radial and tangential directions.The most complicated part of the riser reactor is the feed injectingzone.The complicated configuration of the turbulent gas-solid two-phase flows would exert a great influence onthe results of interphase heat transfer and cracking reactions.     

小型提升管反应器流动-反应耦合模拟

在提升管气固两相湍流流动模型和重油反应动力学集总模型的基础上,利用Fluent软件建立了催化裂化提升管反应器气固两相流动与反应耦合模型,对实验室小型提升管反应器进行了数值模拟,考察了气固两相的流动、传热、传质与反应过程。结果表明,提升管反应器内气固两相在轴向和径向的流动、传热与反应的分布不均匀。在入口附近。原料和催化剂温度变化显著,各组分的浓度变化剧烈,在提升管上部,变化平缓。反应器出口各组分质量分数的模拟值和实验值基本吻合。说明该模型对提升管反应器出口参数和反应结果具有较好的预测性。     

Interactions of flow and reaction in fluid catalytic cracking risers

Fluid catalytic cracking (FCC) is the primary conversion process in oil refining. The performance of an FCC riser strongly depends on the interactions between oil/catalyst flow and cracking kinetics, but most FCC riser models do not consider such interactions. Accordingly, this work develops a computationally simple model capturing the dominant features of flow‐reaction coupling in the riser's dense phase and acceleration zones. Specifically, the particle–particle collision force and the particle–fluid interfacial force are considered. With a four‐lump kinetic model, the riser model predicts conversion and selectivity from the axial profile of the catalyst‐to‐oil ratio resulting from particle–fluid interfacial momentum transfer. The cracking intensity in the riser bottom zone is much greater than that calculated from conventional riser models, which neglects oil‐catalyst hydrodynamic coupling and catalyst dilution due to volume expansion. The present model compares well with published data and predicts conversion‐selectivity patterns that are qualitatively different from those obtained from conventional models. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

湍流气固两相流动状况的数值模拟

应用已建立的提升管反应器固两相流动反应模型,对工业催化裂化提升管反应器内在有传热及裂化反应时的湍流气固两相流动进行了数值模拟,得到了气固两相湍充动状况的详细信息,揭示了提升管内部有反应和传热时气固两相湍流流动的基本特征。模拟结果表明,在轴向,径向和圆周方向都存在着流动,湍能与率剂颗粒浓度的不均匀分布,进料段内的流动是整个反应器最复杂的部分。工业提升管反应器内这一复杂的气固两相湍流流动必将对传热和裂