提升管反应器数值模拟与热力学分析

发布时间：2018-07-04 11:40

本文选题：催化裂化 + 提升管反应器　；参考：《中国石油大学(华东)》2015年硕士论文

【摘要】：提升管反应器是炼油催化裂化装置中最为重要的组成部分。对提升管内化学反应过程进行深入研究具有重要意义,尤其是对反应过程进行定量的热力学分析将弥补现有研究的不足。本文利用计算流体力学方法(CFD),首先建立了提升管反应器的欧拉双流体流动-反应耦合模型用以模拟提升管内的流动、反应和传热情况。之后利用熵平衡关系,建立了提升管反应器内化学反应过程的热力学分析方法,并将热力学分析方法与流动-反应耦合模型相结合,对提升管内不可逆的催化反应过程进行热力学定量描述。首先利用计算流体力学方法对一新型结构提升管反应器进行数值模拟,并通过对比计算数据与设计数据验证所建流动-反应模型的准确性。通过数值计算,详细考察了该提升管内部两相速度分布、催化剂浓度分布、两相温度分布及反应过程。对该新型结构提升管的计算表明,提升管进料段喷嘴处油气高速射流会对管内流动状态、气固接触效率以及传热和反应情况造成显著影响。提升管径向上存在速度、颗粒浓度以及温度梯度,随着流动、反应的充分发展,这一不均匀性将沿着提升管高度逐渐减弱。径向梯度的出现也反映出进料喷嘴角度对流场的影响,径向湍动效果、动量传递的强烈程度都将进一步对反应深度和传热造成影响。为进一步验证提升管双流体假设的合理性,建立了考虑汽化过程的提升管气-液-固三相模型以考察液雾颗粒在管内的存在及变化情况。结果表明,液雾颗粒仅存在于喷嘴上方3~4m高度处,之后便快速汽化为气相,有效证明了提升管内两相模拟的合理性。在利用熵平衡关系建立提升管内催化反应过程热力学分析方法的过程中,根据现有实验数据和文献报道,首先对集总动力学模型中各集总的热力学性质进行了标定计算,之后提出了不可逆催化反应过程所造成的熵产生的计算方法。通过程序语言C编写了用户自定义函数并将其嵌入前述提升管流动-反应耦合模型中进行数值计算,对实验室小型等径提升管和一变径提升管进行了热力学分析与对比。结果表明,变径段由于其大剂油比、适宜的停留时间,使得快速反应段反应程度加深、过程不可逆性增大,从而造成全管内反应过程的熵产生和有效能损失的相应增大。
[Abstract]:Riser reactor is the most important component of FCC unit. It is of great significance to study the chemical reaction process in the riser, especially the quantitative thermodynamic analysis of the reaction process will make up for the shortcomings of the existing research. Based on the computational fluid dynamics (CFD) method, an Eulerian two-fluid flow-reaction coupling model is established to simulate the flow, reaction and heat transfer in a riser reactor. Then, the thermodynamic analysis method of chemical reaction process in riser reactor is established by using entropy equilibrium relationship, and the coupling model of flow-reaction is combined with the thermodynamic analysis method. The irreversible catalytic reaction process in the riser is described quantitatively by thermodynamics. A new type of riser reactor was numerically simulated by computational fluid dynamics (CFD), and the accuracy of the fluid-reaction model was verified by comparing the calculated data with the design data. The two-phase velocity distribution, catalyst concentration distribution, two-phase temperature distribution and reaction process in the riser were investigated numerically. The calculation of the new type of riser shows that the high velocity jet of oil and gas at the nozzle of the feed section of the riser will have a significant effect on the flow state, gas-solid contact efficiency, heat transfer and reaction in the pipe. There are velocity, particle concentration and temperature gradient in the riser. With the development of the flow and reaction, the inhomogeneity will gradually decrease along the riser height. The appearance of radial gradient also reflects the influence of inlet nozzle angle on the flow field. The effect of radial turbulence and the intensity of momentum transfer will further affect the reaction depth and heat transfer. In order to further verify the rationality of two-fluid hypothesis in riser, a gas-liquid-solid three-phase model of riser considering vaporization process was established to investigate the existence and variation of liquid-fog particles in the pipe. The results show that the liquid mist particles only exist at the height of 3m above the nozzle, and then vaporize rapidly to gas phase, which effectively proves the rationality of two-phase simulation in the riser. In the process of establishing thermodynamic analysis method of catalytic reaction process in riser by using entropy equilibrium relationship, the thermodynamic properties of each set in lumped kinetic model are calibrated and calculated according to the available experimental data and literature reports. After that, the calculation method of entropy production caused by irreversible catalytic reaction is proposed. The user-defined function is programmed by programming language C and embedded in the fluid-reaction coupling model of the riser mentioned above. The thermodynamic analysis and comparison of the laboratory small equal-diameter riser and a variable-diameter riser are carried out. The results show that the reaction degree of the rapid reaction section is deepened and the process irreversibility is increased due to its large ratio of solvent to oil and the appropriate residence time, which results in the entropy generation and the loss of effectiveness of the whole reaction process increasing accordingly.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE96

【参考文献】