催化蒸馏法干气制乙苯计算机模拟

针对催化蒸馏法干气制乙苯过程,建立非平衡级模型,并进行了计算机模拟.结果表明,非平衡级模型可用于模拟催化蒸馏法干气制乙苯过程,模拟结果与试验值吻合较好.以模拟结果为依据,考察了各工艺条件的影响,并提出了催化蒸馏法干气制乙苯过程适宜的工艺条件.     

Y沸石催化剂催化蒸馏干气与苯制乙苯

采用耐水、耐硫的改性Y沸石催化剂,对催化蒸馏干气与苯制乙苯工艺进行了研究,得到了较佳的催化蒸馏反应工艺条件。乙烯重量空速、反应温度和压力、回流比是影响乙烯转化率的主要因素,而乙苯选择性随反应条件的变化较小,一般在90%~95%。反应段温度分布均匀,乙苯等反应产物的含量很低,一般不超过2%(mol)。     

催化蒸馏元件的流体力学性能

采用内径为206 mm的有机玻璃塔,在常温常压条件下,以空气和水为介质,对一种新型的反应液渗流式催化蒸馏元件进体力学实验研究,并研究了气相流通截面分率和固体催化剂在元件内装填高度对流体力学参数的影响;利用最小二乘法回归实验数据得到了床层压降、动持液量及泛点气速的预测关联式,各关联式误差均在±4.5%以内,可作为工业设计的参考依据。     

垂直筛板塔内催化剂筐式装填结构的流体力学研究

基于垂直筛板帽罩的垂直特性,开发了一类用于催化精馏的新型催化剂筐式装填结构.该结构的主要特点为:均匀装填催化剂的催化剂筐置于帽罩外侧;气相与被提升的液相在帽罩内形成的气液混合物从罩孔喷出后进入筐内的催化剂床层:床层内的气-液-固的有效接触可显著促进非均相催化反应的进行.用空气-水体系在内径ψ48 mm冷模塔上考察了催化剂筐式装填结构的结构参数(帽罩形式、帽罩孔径和开孔率)对装填结构流体力学性能的影响;并根据操作范围和干板、湿板压降等因素对其进行了优化.研究结果表明基于柱形帽罩的催化剂筐式装填结构的气-液-固三相的接触状态优于基于矩形帽罩的:帽罩孔径ψ2 mm和开孔率0.056时的气-液-固接触效果和塔操作状态最佳.     

柠檬酸处理对FCC干气与苯烷基化催化剂的影响

采用ZSM-5/ZSM-11共结晶分子筛催化剂,在固定床反应装置上对催化裂化干气与苯制乙苯进行考察。 NH₃-TPD结果表明,随着水热处理条件的苛刻, 催化剂的酸量和酸强度均下降, 虽然这些催化剂上干气中乙烯转化率变化不明显, 但产物中二甲苯含量大幅度下降。 柠檬酸对分子筛催化剂进行改性处理后, 可明显降低催化裂化干气与苯制乙苯中二甲苯杂质含量, 原因可能为催化剂大的比表面积和孔容改善了原料的传质能力, 从而抑制了二甲苯的生成。     

SEB-08稀乙烯制乙苯催化剂在安庆石化干气制乙苯装置上的工业应用

本文介绍了中石化上海石油化工研究院研制的SEB-08新型高效稀乙烯制乙苯催化剂在中石化安庆分公司10.6万吨/年乙苯装置的使用情况,与装置原使用催化剂相比,该催化剂具有处理量大、乙烯转化率高、乙基选择性好、活性和抗波动能力强、稳定性好、装填量少且装填方便、投用前不需要活化、再生次数少等优点,使用过程中表现出优异的性能,乙烯转化率始终保持在96%以上,乙苯产品的纯度不低于99.80%,产品中杂质二甲苯的含量不大于600 ppm,为现有干气制乙苯装置提高产品乙苯品质,降低物耗和能耗,提高经济效益,增加竞争力提供了强有力的技术保障。     

干气制乙苯装置运行及新工艺技术开发

介绍了抚顺石化公司的国内首套催化干气制乙苯气相烷基化(烃化)和液相烷基转移(反烃化)组合的第三代技术工业装置的特点及工业运行情况:通过优化工艺设计,大幅降低了乙苯生产能耗和成本;烃化催化剂和反烃化催化剂呈现出优异的反应活性、抗杂质性能和反应稳定性;由于装置未设干气脱丙烯单元,产品中二甲苯含量略高,达到国家一级品要求;对未来装置技改及更换新一代高性能催化剂提出了建议。所开发的干气与苯变相催化分离制乙苯新一代技术使烃化反应温度进一步降到165~200℃,产品中二甲苯杂质降到100×10-6以下,100 m L规模催化剂(DL0805)放大试验表明,随干气原料中乙烯浓度升高其转化率显著上升,新工艺技术更适于以高乙烯浓度的干气为原料来生产乙苯;反应器中下部适量多乙苯的注入可促进烃化段新生成的多乙苯的完全转化,从而烃化和反烃化过程可集中于一个反应器中进行;DL0805催化剂呈现出较好的反应活性、乙基化选择性及反应稳定性。     

固定床反应器催化剂密相装填过程床层料面监测系统构建与研究

催化剂密相装填过程中反应器内部直观可视性差,无法实时掌握反应器内床层堆积状态,影响布料控制和装填质量。本文以某单位固定床反应器为研究示例,构建了一套催化剂密相装填过程的床层料面监测系统,从机械结构设计、电气控制逻辑、软件窗口架构完成系统设计。使用脉冲微波雷达获取特征点距离,计算空间分布,根据空间分布使用自然条件下三次样条插值法构建料面图像。考察系统对多种形态料面的监测效果,探讨环境光照、催化剂粒径对系统可靠性的影响。结果表明,系统操作维护简单,具有较高的成像分辨率和测量精度,中心位置监测效果优于边缘;生成的三维毯式图像与径向料面分布图极大提高了密相装填过程床层料面信息的可读性;监测系统具有较强的鲁棒性,能适应反应器内多工况下的监测需求。     

催化剂装填结构对C3馏分催化蒸馏选择加氢过程的影响

考察了填料状催化剂散装结构、筛板-填料状催化剂复合结构、规整填料与普通催化剂交错排列结构等用于C3馏分中丙炔、丙二烯催化蒸馏选择加氢过程的反应效果,综合考虑催化剂制备的难易、工业装置长周期运转的必要性、传质对反应的影响等因素,推荐在工业装置上采用规整填料与催化剂交错排列结构。     

变床层高度固定床反应器的分析

在分子筛催化剂苯气相乙基化制乙苯过程开发中,根据该反应过程的特点,提出了变床层高度固定床反应器的构想。利用催化剂失活动力学模型,通过模拟计算,对常规固定床反应器和变床层高度固定床反应器的性能进行比较,结果表明后者对延长反应器操作周期和改善反应选择性均有显著作用。上述分析已在300吨乙苯/年中试反应器的运转中得到证实。     

Bed structure and its impact on liquid distribution in a trickle bed reactor

Trickle bed reactors, which has been a workhorse for the process and refining industry for many decades, are progressively being challenged to provide solutions to deep processing of feedstocks. It is known that the structure of the packed bed which is formed with a certain arrangement of catalyst particles in the three-dimensional space within the reactor modulates in an unknown fashion the flow of fluids in the trickle bed, and in turn affects the conversion and selectivity in the trickle bed. Under deep processing conditions, the impact of the bed structure in modulating the overall reactor performance in a trickle bed is not as yet established. The question begets three sequential studies: estimating and quantifying the bed structure, measuring the liquid distribution, and estimating transport parameters (that are dependent on the bed structure and liquid distribution) so that the overall performance metrics as a reactor may be quantified. This contribution relates to the second of these questions, the first being already addressed to some extent by our earlier work. The current investigation aims at quantifying the effect of structure of the packed bed on hydrodynamics of the reactor. The impact of various packing techniques is discussed along with the development of correlations for two-phase pressure drop and dynamic liquid holdup. Liquid distribution is studied in depth for various operating parameters such as gas and liquid superficial velocities and column aspect ratio for uniform and non-uniform packing methods. The packing devices consist of various inserts attached to a hopper which can generate packing structures having void fraction in the range of 37.2%–46.4%. The maldistribution factor and flow maps for various aspect ratio of column suggest that maldistribution rises along with the increased channeling effect along the height of the column. Uniformly packed bed were measurably less prone to maldistribution along the length than the non-uniformly packed beds.     

Pressure drop hysteresis in trickle bed reactors

An understanding of the hydrodynamics of trickle bed reactors (TBR) is essential for their design and prediction of their performance. Flow variables, packing characteristics, physical properties of fluids and operation modes influence the behavior of the TBR. The existence of multiple hydrodynamic states or hysteresis (pressure drop, liquid holdup, catalyst wetting, gas-liquid mass transfer) is due to the different flow structures in the packed bed and can be attained by a set of different operating procedures. Experiments were performed to study the effect of liquid and gas velocity, liquid surface tension, liquid viscosity and the particle diameter of the packing on two-phase pressure drop hysteresis. The parallel zone model for pressure drop hysteresis in the trickling flow was used for analysis of experimental data and flow structure. Theoretically predicted pressure drop hysteresis loop is in satisfactory agreement with experimental data.     

XY-S型催化剂在全密度聚乙烯装置上的应用

从流化床反应器基本工艺出发,通过对反应过程中的乙烯分压,n(H2)/n(C2H4),n(C4H8)/n(C2H4),两种催化剂质量比等的调整,反应器静电、流化床上下部的线型低密度聚乙烯(LLDPE)质量比、松密度、反应压力等参数均受控。催化剂活性随着XY-S型催化剂加入比例的增大而下降,w(XY-S)为100%时,催化剂平均活性达6.572 t/kg,与w(XY-S)为50%,70%相比,催化剂活性下降了14.3%～18.7%。产品合格率达100%,国产XY-S型催化剂在全密度聚乙烯装置上成功应用,基本满足装置长周期运行,达到了降低生产成本和催化剂国产化的目的。     

三相鼓泡淤浆床环氧乙烷合成反应器数学模拟及工程分析

建立了加压三相鼓泡淤浆床环氧乙烷合成反应器的数学模型 ,计入了催化剂颗粒在床层中沉降形成沿床高浓度分布对反应的影响以及由于惰性液相载体部分返混对传递的影响 ,进一步利用经实验验证的上述数学模型模拟不同表观气速、床高、反应器直径 (扣除传热元件截面积 )、进口乙烯摩尔分数等参数对床层中催化剂浓度随床高的分布、出口环氧乙烷摩尔分数、环氧乙烷选择率以及单位质量催化剂环氧乙烷年产量的影响 .通过模拟分析预示了工业三相床环氧乙烷反应器的合理尺寸、表观气速、环氧乙烷选择率以及时空产率 ,为工业化提供必要的设计依据     

旋转填料床精馏过程流体力学性能研究

在对旋转填料床精馏特性研究的基础上,以塑料多孔板为填料,乙醇-水为体系,在全回流操作条件下,进一步研究了气相动能因子F、超重力因子β和回流量L对旋转填料床流体力学特性的影响,证明了旋转填料床的低耗能特性。     

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.     

Hydrodynamics of Shaft Drying of Granulated Poly(Ethylene Terephthalate)

The effect of the poly(ethylene terephthalate) granule size on bed hydrodynamics in blowing with an ascending stream of drying agent was investigated. It was found that the pressure loss of the bed is more dependent on its height and average air speed the smaller the equivalent granule diameter is.     

Computational fluid dynamics (CFD) modeling of spouted bed: Influence of frictional stress, maximum packing limit and coefficient of restitution of particles

Following the previous article [Du, W., Bao, X., Xu, J., Wei, W., 2006. Computational fluid dynamics (CFD) modeling of spouted bed: assessment of drag coefficient correlations. Chemical Engineering Science 61 (5), 1401-1420], this contribution describes the influences of the frictional stress, maximum packing limit and coefficient of restitution of particles on CFD simulation of spouted beds. Using the two-fluid method embedded in the commercial CFD simulation package Fluent 6.1, the spouting hydrodynamics of a cylindrical-conical spouted bed was simulated and verified with the experimental data of He et al. [He, Y.L., Lim, C.J., Grace, J.R., Zhu, J.X., Qin, S.Z., 1994a. Measurements of voidage profiles in spouted beds. Canadian Journal of Chemical Engineering 72 (4), 229-234; He, Y.L., Qin, S.Z., Lim, C.J., Grace, J.R., 1994b. Particle velocity profiles and solid flow patterns in spouted beds. Canadian Journal of Chemical Engineering 72(8), 561-568]. The results showed that, for coarse particles, the frictional stress is important only for the annulus computation and has no obvious effects on the hydrodynamics of the solids flow in the spout region. The specification of the maximum packing limit could significantly affect the properties of the pseudo-fluid phase of the particles by changing the radial distribution function. The strong dependence of the pseudo-fluid properties of the particle phase, such as pressure, bulk viscosity and shear viscosity, on the granular temperature accounts for the influence of the coefficient of restitution of particles on CFD modeling. The solids volume fraction at loose packing state is suitable for spouted bed simulations, and a pretest of the coefficient of restitution of particles must be conducted when no experimental datum is available.     

网板填料复合旋转床的流体力学与传质性能

开发了一种新型的气液接触设备——网板填料复合旋转床。常压下以空气-水物系和乙醇-水物系在网板填料复合旋转床中进行流体力学与传质性能实验,考察了气液流量和转子转速对网板填料复合旋转床压降和传质性能的影响。实验结果表明,气体流量和转子转速的增大均使干、湿床气相压降增大;液体流量的增加对湿床压降的影响不明显。回流量和转速的增加均使等板高度减少至一定值后几乎不变。网板填料复合旋转床具有通量大、效率高、压降小的特点。     

Comparison of vertically aligned carbon nanotube array intercalated production among vermiculites in fixed and fluidized bed reactors

Vertically aligned carbon nanotube (CNT) arrays with ordered nanostructure and extraordinary performance have become an important advanced material. CNTs were synchronously grown with high density to form aligned morphology, while the fine agglomerated structure was sensitive to the packing style of catalyst particles. Thus, synthesis of CNT arrays in a fixed bed or fluidized bed is an important issue. We reported that CNT arrays were grown from ethylene on a lamellar catalyst in a fixed bed reactor and a fluidized bed reactor, respectively. The reactor style affected the intercalated growth of CNT arrays greatly. The qualities of CNT array products in the fixed bed showed a distribution along the axis direction. The CNT arrays obtained at the top of the fixed bed were of good alignment and small diameter; while for the products obtained at the bottom of the reactor, CNT array blocks with higher densities, larger diameter, shorter length, and more defects, were formed. When CNT arrays were grown in a fluidized bed, they were of homogeneous structure, low densities, small uniform diameter, and had little defects, which can be attributed to available space, uniform temperature and reactant distribution in the fluidized bed reactor. These favored the mass production of CNT arrays with uniform properties in a fluidized bed reactor.