催化裂化沉降器内气固两相流动的数值模拟分析

本文利用计算流体力学软件FLUENT6.1对工业尺度下沉降器内的压力分布、油气和催化剂的速度分布以及催化剂的浓度分布等进行了较详尽的数值模拟,确定了沉降器内的流动死区和较易结焦的部位,为研究催化裂化沉降器内的结焦动力学提供了定量的参考依据.     

RFCC沉降器内流动及传热过程的数值模拟

针对重油催化裂化(RFCC)沉降器结焦问题,采用计算流体力学方法,建立了一套160万吨/年工业重油催化裂化(RFCC)沉降器油气流动和传热的数学模型。通过模拟研究考察了沉降器内的速度、温度以及油气分压分布,结果表明,油气运动速度低、分压大易导致结焦。通过计算粗旋、顶旋以及汽提段等各部分油气在沉降器内的停留时间分布发现,粗旋料腿处进入沉降器的油气含量高且停留时间很长,对沉降器结焦的影响最大,因此降低粗旋料腿处进入沉降器内的油气量是防结焦的关键。     

重油催化裂化沉降器结焦的研究进展

分析了重油催化裂化 (RFCC)沉降器结焦的影响因素和机理。反应油气中含有催化剂颗粒以及油气中重组分的冷凝是沉降器结焦的物理因素 ,而重芳烃、胶质、沥青质的高温缩合和油气中烯烃和二烯烃的环化聚合反应则是沉降器结焦的化学因素。通过对液相重组分高温缩合机理、相分离生焦机理和自由基反应机理等沉降器结焦机理的分析 ,认为沉降器中油气的气、液相分别遵循不同的结焦历程 ,抑制沉降器结焦的关键在于抑制反应油气中重组分的冷凝和缩短反应油气的停留时间     

催化裂化装置沉降器防结焦技术

对炼油企业来说,催化裂化设备是石油炼制二次加工中的关键部分。随着原油供应量日益增加,炼油厂中的催化裂化掺渣比日益增大的环境下,催化裂化装置沉降器的防结焦工作已刻不容缓。为此,本章重点剖析了催化裂化装置沉降器结焦的成因和特性,并主要研究了催化裂化装置沉降器防结焦问题的技术应用,希望能够为催化裂化装置解决类似问题提供一定的帮助。     

重油催化裂化沉降器结焦历程分析

沉降器结焦需具备2个条件:存在易结焦物质,存在结焦的环境和条件。在重油催化裂化沉降器中结焦物质包括油气组分、油液滴和催化剂颗粒,结焦的环境和条件指沉降器内的物料流场、温度场和浓度分布情况。分析了沉降器中气相组分、油液滴和催化剂颗粒等结焦物质的结焦历程,提出为了定量掌握结焦历程中各个过程的细节有待于进一步进行研究的问题。     

流化催化裂化沉降器内油气的流动规律

采用Reynolds应力输运模型对一种催化裂化沉降器内的油气流动状况进行了全尺寸的数值模拟.在计算过程中未对沉降器的复杂结构进行简化,所建立的几何模型包括沉降器内部区域和两级旋风分离系统内部区域的全部流动空间.计算结果表明:粗旋分离器排气管出口的油气呈旋转射流状态喷出,弥漫于庞大的沉降器空间,流动缓慢,经历了较长的停留时间后才能进入顶旋分离器;大量油气在高温下长时间的停留将导致沉降器内大量结焦,对催化裂化的安全长周期运行造成隐患.     

催化裂化沉降器结焦过程的研究进展

阐述了沉降器内油气结焦的原理,影响因素及各因素的作用,分析了结焦的形成过程,平均停留时间对结焦量的影响以及流动状态对结焦形貌的影响,介绍了防止沉降器结焦的研究进展情况和存在的问题.     

催化裂化装置沉降器跑剂情况分析

中国石油化工股份有限公司金陵分公司1.3Mt/a催化裂化装置运行至第54个周期,2018年11月沉降器跑剂致使装置停工,停工后检查发现为沉降器集气室结焦掉落堵塞旋分器料腿,分析原因为沉降器结焦所致。基于此,通过对结焦原因进行分析后,提出了相应的应对措施,降低了装置非计划停工的可能性。     

石油催化裂化沉降器抗结焦的研究与应用

重油催化沉降器内结焦严重,威胁装置的长周期平稳运行。中国石油大学(北京)针对沉降器结焦问题进行了较深入系统的数值模拟与实验研究,揭示了结焦的形成、发展、粘壁的机理和油气流动环境对结焦的影响,从沉降器工程装备设计方面开发了系列沉降器结焦综合防治技术并已成功应用于催化裂化工业装置,为重油催化裂化装置的长周期安全运行提供了技术支持。     

催化裂化沉降器的结焦原因和防焦措施

随着炼油厂催化裂化掺渣比的提高，催化裂化沉降器结焦日益严重，并直接影响威胁到催化裂化装置的正常运行。分析了原料性质、催化剂浓度和反应条件等因素对催化裂化沉降器结焦的影响，并通过总结国内外所采取的一些防焦措施，提出了今后的发展趋势和要求。     

带隔流筒旋流快分系统新型工业催化裂化沉降器内气相流场的数值模拟

采用RNG k-e湍流模型模拟带隔流筒旋流快分系统工业催化裂化沉降器内的气相流场,基于沉降器内气相流场的分析,考察了压力平衡管截面尺寸及封闭罩直径对封闭罩内外气量分配的影响. 结果表明,进入封闭罩外的汽提油气量随平衡管截面边长增加而增大,随封闭罩直径增加而减小. 封闭罩阻止了分离系统内油气进入沉降器中. 压力平衡管通过抽吸作用将封闭罩外的汽提油气快速引出沉降器,使封闭罩外的汽提油气在沉降器内的总停留时间降至13 s以下. 平衡管截面边长小于310 mm时,汽提气的引出分为两路;平衡管截面边长大于310 mm时,汽提气全部进入封闭罩外部,且分离系统内的少量油气向下流出分离系统至沉降器内. 封闭罩直径为3.8 m时,99%以上的油气都进入封闭罩外部.     

RFCC沉降器内油浆气化率的初步研究

The vaporization ratios of the slurry at various temperature and partial pressure were calculated with the group-contribution method,and then the phase state of the slurry in the residue fluid catalytic cracking（RFCC） disengager was determined.This research could provide some advices on how to select the technological conditions to decrease the coking in the RFCC disengager.The oil gas temperature and the slurry partial pressure had signifi- cant effects on the vaporization ratio of the slurry.Increasing the oil gas temperature and reducing the slurry partial pressure could effectively slow down the coking speed in the RFCC disengager.According to the calculation results, a correlation was established to predict the vaporization ratio of the slurry under different operating conditions.     

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 catalytic cracking(FCC)riser reactors were carried out employingthe developed turbulent gas-solid two-phase flow-reaction model for FCC riser reactors given in Part Ⅰ of thepresent paper.Detailed information about the turbulentflow fields in the riser reactor obtained revealed the basic characteristics of the gas-solid two-phase turbulent flows when heat transfer and catalytic cracking reactions were co-existing in the riser. Results showed that the distributions of the flow, the turbulence kinetic energy and the catalyst particle concentration arenot uniform in the axial, radial and tangential directions. The most complicated part of the riser reactor is the feed injecting zone. The complicated configuration of the turbulent gas-solid two-phase flows would exert a great influence on the results of interphase heat transfer and cracking reactions.     

液固两相流中磨蚀-腐蚀的数值模拟

Erosion-corrosion of liquid-solid two-phase flow occurring in a pipe with sudden expansion in cross-section is numerically simulated in this paper. The global model for erosion-corrosion process includes three main components: the liquid-solid two-phase flow model, erosion model and corrosion model. The Eulerian-Lagrangian approach is used to simulate liquid-solid two-phase flow, while the stochastic trajectory model was adopted to obtain properties of particle phase. Two-way coupling effect between the fluid and the particle phase is considered in the model. The accuracy of the models is tested by the data in the reference. The comparison shows that the model is basically correct and feasible.     

Numerical Simulation on Gas-Solid Two-Phase Turbulent Flow in FCC Riser Reactors (I) Turbulent Gas-Solid Flow-Reaction Model

Gas-solid two-phase turbulent flows, mass transfer, heat transfer and catalytic cracking reactions are known to exert interrelated influences in commercial fluid catalytic cracking(FCC) riser reactors.In the present paper, a three-dimensional turbulent gas-solid two-phase flow-reaction model for FCC riser reactors was developed. The model took into account the gas- solid two-phase turbulent flows, inter-phase heat transfer, mass transfer, catalytic cracking reactions and their nterrelated influence. The k-V-kp two-phase turbulence model was employed and modified for the two-phase turbulent flow patterns with relatively high particle concentration. Boundary conditions for the flow-reaction model were given. Related numerical algorithm was formed and a numerical code was drawn up. Numerical modeling for commercial FCC riser reactors could be carried out with the presented model.     

水驱油藏油滴变形流动研究

近年来,随着注水开发进入特高含水阶段,剩余油的分布形态和流动状况发生了很大变化。为明确微观孔隙剩余油的形成机理,采用计算流体动力学软件Fluent对水驱油藏油滴的变形流动进行数值模拟计算,分析孔道的倾斜角度,润湿角和单根毛管并联双孔道对油滴变形流动规律的影响。研究表明:岩石的不同孔隙倾斜角度可影响油滴的变形,当孔隙与竖直方向存在夹角时,重力的作用不可忽略,驱替方向与重力方向的夹角可影响油滴的变形。并且油滴的变形随着润湿角的增大而更加明显。在单根毛管并联双孔道中,由于毛管半径不同剩余油的运移速度不同,先到达出口的油滴会对其余油滴产生阻碍其运动的力。研究结论可为进一步研究微观孔隙油滴变形机理提供理论依据。