Key observations from a comprehensive FCC study on Canadian heavy gas oils from various origins: 1. Yield profiles in batch reactors

A series of cracking tests in a comprehensive study were conducted on separate occasions involving all or parts of 10 Canadian vacuum gas oil (VGO) feeds and a catalyst. VGOs were cracked in fixed- and fluid-bed microactivity test (MAT) units, the Advanced Cracking Evaluation (ACE) unit, and a modified ARCO riser reactor. Several important observations from this study were reported, including the effects of gasoline precursors on the maximum gasoline yields and aromatics in feeds on the conversion levels at which the maximum gasoline yields occurred. Yield profiles were found to be similar in shapes and relative positions between H₂S-free dry gas and catalytic coke for all but one of the feeds. Conversion and yield data obtained from the three batch reactors were compared and discussed. At a given conversion, correlations existed among the fixed- and fluid-bed MAT units, and the ACE for each product yield. A method to check the qualities of MAT and riser data was demonstrated by plotting the coke or total gas selectivity versus the gasoline selectivity.     

Détermination de constantes cinétiques du craquage catalytique par la modélisation du test de microactivité (MAT)

The microactivity test (MAT) for cracking catalyst test works with an approximately plug flow isothermal reactor. The yields at the outlet of such a reactor is numerically computed in the case of lumped kinetic with large molecular expansion and rapid catalyst deactivation expressed versus poison concentration. The poison (coke in cracking reaction) is considered as a product formed by several reaction routes. The results are applied to catalytic cracking kinetic with a four lump model (feedstock, gasoline, gas, coke). The comparison between experimental and computed yields, permits the adjustment of kinetic constants with a set of experimental results obtained from a laboratory scale reactor derived from the MAT. The simulation of concentration profile in the reactor permits a better understanding of the reaction courses.     

MODELING OF GAS OIL CATALYTIC CRACKING IN A FIXED BED REACTOR USING A FIVE-LUMP KINETIC MODEL

A five-lump kinetic model had been developed for modeling of gas oil catalytic cracking. The experiments were carried out in a standard fixed bed micro-activity test (MAT) reactor. Distribution of the cracking product components was determined as a function of temperature. The sequential step optimization method was used to estimate the kinetic constants. A MAT reactor nonisothermal and the unsteady-state model was proposed. The overall heat of the reactions was established from the macroscopic difference of the products' and the reactants' enthalpies. The influence of the feedstock and the reactor temperature was discussed. The reactor and the kinetic models were validated using the experimental MAT results. Simulation results were in good agreement with the experimental data.     

催化汽油氧化脱硫的动力学模型研究

通过脱硫实验及动力学模拟,开展催化汽油氧化脱硫的动力学模型研究.结果表明,汽油脱硫率随着催化剂用量增加、氧化温度提高、氧气分压增大、氧化时间、氧化水油体积比增大均持续提高,而汽油收率逐渐降低.依据反应动力学和萃取相平衡原理,确定了脱硫率和汽油收率模型,并确定了有关模型参数.建立的脱硫率和汽油收率模型在显著性水平α=0.01时均是显著的,具有较高的模拟计算精度.     

Consistency of the ten-lump kinetic model for cracking: Study in a laboratory reactor and use for simulation of an FCCU

The kinetic constants corresponding to the ten-lump kinetic model have been determined by carrying out the cracking of three different feeds in a laboratory reactor under experimental conditions (temperature, contact time, C/O ratio) similar to those of industrial FCC units and using a commercial catalyst. The kinetic constants are independent of the feed composition, which is evidence of the consistency of the ten-lump kinetic model. The kinetic constants determined have been used in the simulation of an FCC unit operated following two strategies (maximization of the yield of gasoline and mean distillates), and in both cases it has been proven that the results of the simulation are in agreement with those of the industrial plant.     

CONSISTENCY OF THE TEN-LUMP KINETIC MODEL FOR CRACKING: STUDY IN A LABORATORY REACTOR AND USE FOR SIMULATION OF AN FCCU

The kinetic constants corresponding to the ten-lump kinetic model have been determined by carrying out the cracking of three different feeds in a laboratory reactor under experimental conditions (temperature, contact time, C/O ratio) similar to those of industrial FCC units and using a commercial catalyst. The kinetic constants are independent of the feed composition, which is evidence of the consistency of the ten-lump kinetic model. The kinetic constants determined have been used in the simulation of an FCC unit operated following two strategies (maximization of the yield of gasoline and mean distillates), and in both cases it has been proven that the results of the simulation are in agreement with those of the industrial plant.     

Translation of MAT Kinetic Data to Model Industrial Catalytic Cracking Units

Bench‐ and laboratory‐scale reactors are required to infer kinetic data for catalytic cracking units. One of the most common methods is the microactivity test (MAT, ASTM D‐3902–92), that emulates the catalyst‐to‐oil ratio using a fixed‐bed reactor and a semibatch accumulator of liquids. Translation of data obtained from MAT tests in order to infer kinetic parameters to model continuous industrial units is, consequently, difficult and uncertain. In this work, the extraction of kinetic data obtained in a MAT reactor is analyzed. Estimation of a kinetic rate equation to evaluate instantaneous conversion in MAT reactors is performed. The activation energy obtained is kinetic and can be used during the modeling of riser reactors. It was possible, also, to infer values of the remaining catalytic activity after each experiment; these values were used to adjust a hyperbolic deactivation function, useful to model industrial riser reactors.     

Kinetic modeling of high-severity fluidized catalytic cracking

This paper presents the results of kinetic modeling of high-severity fluidized catalytic cracking process using a simplified methodology of estimating kinetic parameters. A 4-lump model was used to demonstrate the new approach for modeling the kinetics data that was collected using micro-activity test (MAT) method. MAT experiments were done at 550, 600 and 650 °C. Kinetic parameters for the 4-lump model and the activation energies are presented.     

提升管催化裂化反应过程数值模拟

在气固两相流体动力学模型的基础上.采用基于机理反应的FCC14集总模型.考虑了反应温度、局部固体浓度变化以及流动对反应的影响,建立了重油流化催化裂化流动一一反应耦合模型.模拟结果表明,重油裂化反应主要发生在喷嘴附近区域,在喷嘴附近已经有45%的重油转化为汽油和柴油.随着距离喷嘴位置的增加,汽油产率逐渐上升,但距离喷嘴位置12m以后,汽油产率基本保持不变.从汽油组成变化来看,在整个提升管内汽油中烯烃含量一直处于下降趋势,由喷嘴区域的60wt%降低到提升管出口位置的42wt%左右.汽油烷烃含量一直呈增加趋势,而汽油中环烷烃含量和芳烃含量变化较小.     

灵活多效催化裂化工艺集总动力学模型

针对灵活多效催化裂化(FDFCC)工艺,以工业装置数据为基础建立了重油提升管催化裂化10集总和汽油提升管催化裂化7集总动力学模型,求取了10集总模型的43个动力学参数和7集总模型的18个动力学参数.结果表明,所获得的模型动力学参数是可靠的,所建立的模型能够较好地预测FDFCC装置的产品产率,并对汽油组成和丙烯产率具有良好的预测性.     

基于汽油烯烃转化的催化裂化动力学模型

以催化裂化反应机理为基础,把FCC原料及产品按馏程和化学组成进行集总划分.考虑氢转移、芳构化等二次反应,通过对反应网络的合理简化,提出了一种分子水平的动力学模型.通过参数估计求取18个动力学速度常数,建立集总动力学模型以预测汽油的化学结构组成.研究结果表明：该模型能较好预测不同条件下的产率分布,而且可以预测汽油组成分布,有助于降低汽油烯烃含量的研究.     

Fluid catalytic cracking feed hydrotreatment and its severity impact on product yields and quality

This paper investigates the effect of fluid catalytic cracking (FCC) feed hydrotreatment and its severity increase on product yields and quality obtained in a commercial and a laboratory MAT FCC units. The hydrotreatment of Ural heavy vacuum gas oil reduces not only sulfur, nitrogen, Conradson carbon and metals content in the FCC feed but also increases the mononuclear aromatic hydrocarbons content by 8% absolute at almost no change in the total aromatics content. Regardless of this 8% increase of the mononuclear aromatics in the hydrotreated FCC feed the conversion increase in both commercial and laboratory MAT units was only 2%. The severity increase in the FCC feed hydrotreater leads to a higher conversion in the FCC, higher hydrogen transfer rate that results in higher isobutane/butylenes ratio, lower gasoline olefins content, and higher gasoline motor octane number. The hydrotreatment of the Ural heavy vacuum gas oil exhibited the same changes in FCC catalyst selectivities: lower coke and LCO selectivities and higher gasoline selectivity in both commercial riser FCC unit that has between 2 and 3 s time on stream, and the fixed bed reactor MAT unit, that has 30 s time on stream.     

汽油催化改质反应过程数值模拟

在汽油催化反应动力学模型和气固两相流动模型的基础上,建立了汽油改质反应过程流动-反应耦合模型。针对不同的转化反应器构型（提升管、提升管-床层反应器）,对汽油改质过程进行了数值模拟。模拟结果表明,对提升管反应器而言,汽油经过低温改质反应后,烯烃含量可以从35.1%降低到18%左右,烯烃降低幅度可达48%,汽油中烯烃主要转化为异构烷烃。另外,随着反应温度的升高,汽油转化反应中的裂化反应增强,导致汽油收率下降。对于提升管-床层反应器而言,汽油中的烯烃含量可以降得更低,在床层空速4时,烯烃含量可以降低到5%左右,汽油收率为80%左右。     

Effect of Feedstocks on High‐Severity Fluid Catalytic Cracking

A novel fluid catalytic cracking (FCC) process, that utilizes a downer reactor, has been developed to enhance the yield of light olefins under high‐severity reaction conditions. The effect of heavier feedstock on this high‐severity fluid catalytic cracking (HS‐FCC) process has been investigated using a small‐scale HS‐FCC pilot plant (0.1 b/d). Hydrotreated and virgin vacuum gas oils (VGO), hydrotreated and virgin atmospheric residues (AR) were used as test‐feeds in a previous study. The yield of desired products, such as gasoline and light olefins, produced from virgin VGO cracking was 79 wt.‐%, which is much higher than that obtained from a conventional FCC process. In the case of hydrotreated VGO, the yield of desired products decreased to 76%, however. On the other hand, AR feeds exhibited a performance similar to VGO with a slight increase in coke formation. In this study microactivity test (MAT) results are reported in which the activity and selectivity of the Y‐zeolite based catalyst is evaluated. Kinetic modeling was also done based on a four‐lump reaction model.     

Utilization of ZSM-5/MCM-41 composite as FCC catalyst additive for enhancing propylene yield from VGO cracking

A micro-mesoporous ZSM-5/MCM-41 composite molecular sieve (ZM13) was synthesized and tested as an FCC catalyst additive to enhance the yield of propylene from catalytic cracking of vacuum gas oil (VGO). The catalytic performance of the additive was assessed using a commercial equilibrium USY FCC catalyst (E-Cat) in a fixed-bed micro-activity test unit (MAT) at 520?°C and various catalyst/oil ratios. MCM-41, ZSM-5 and two ZSM-5/MCM-41 composites were systematically characterized by complementary techniques such as XRD, BET, FTIR and SEM. The characterization results showed that the composites contained secondary building unit with different textural properties compared to pure ZSM-5 and MCM-41. MAT results showed that the VGO cracking activity of E-Cat did not decrease by using these additives. The highest propylene yield of 12.2 wt% was achieved over steamed ZSM-5/MCM-41 composite additive (ZM13) compared with 8.6 wt% over conventional ZSM-5 additive at similar gasoline yield penalty. The enhanced production of propylene over composite additive was attributed to its mesopores that suppressed secondary and hydrogen transfer reactions and offered easier transport and accessibility to active sites. Gasoline quality was improved by the use of all additives except MCM-41, as octane rating increased by 6?C12 numbers.     

Establishment and solution of eight-lump kinetic model for FCC gasoline secondary reaction using particle swarm optimization

An eight-lump kinetic model contained 21 kinetic parameters was proposed to describe the secondary reaction process of fluid catalytic cracking (FCC) gasoline. The model was solved by hybrid particle-swarm optimization (HPSO) which incorporated evolutionary strategies and the simulated annealing method into particle swarm optimization (PSO). A series of experiments were carried out in a riser reactor over an improved Y zeolite catalyst with different temperatures, catalyst to oil ratios and vapor residence times. The product distribution was obtained to estimate the 21 kinetic parameters of model; the calculated results obtained using the HPSO algorithm agreed well with the experimental results.     

Diffusion and reactivity of gas oil in FCC catalysts

This study considers the effects of diffusion and intrinsic catalytic reactivity for the cracking of gas oil on FCC catalysts. A four‐lump kinetic model, initially developed in a novel CREC Simulator, is employed to estimate the unconverted gas oil, the gasoline, the light gases and the coke fractions. The model incorporates a modified Thiele modulus, based on zeolite crystal properties, and an effectiveness factor. The calculated effectiveness factor is found to increase with the gas oil conversion and to decrease with the intrinsic rate constant and the zeolite crystal size. The proposed model predicts that crystal size changes in the 0.13 to 1.3 μm range affect both primary and secondary cracking reactions and the yields of gasoline, coke and light gas yields.     

β分子筛的催化裂化性能考察

以重油（70%新疆蜡油掺和30%新疆渣油）为原料,在FFB和ACE装置上对3种不同硅铝质量比β分子筛和工业应用的ZSM-5分子筛制备的催化裂化助剂的反应性能进行对比评价。结果表明,β分子筛对重油组分的裂化能力强于ZSM-5,对汽油组分的选择裂化能力弱于ZSM-5,液化气增加量小于ZSM-5,提高汽油辛烷值能力与ZSM-5相当。同时,随着β分子筛硅铝质量比升高,其催化裂化产物中汽油和总液收增加,重油减少。因此,β分子筛助剂适用于以追求燃料汽油生产为主的炼油企业,满足液化气增加不多和提高汽油辛烷值的需要。     

Model-based geometry optimization of a Nitsch cell using the Fisher information matrix

In order to experimentally estimate the rate-determining steps and the kinetic parameters of interfacial reaction models, e.g. for the design of reactive-extraction equipment, the Nitsch cell and its variants are broadly used. In the present study, an optimized Nitsch cell was designed with the help of a kinetic model from the literature to improve the quality of the measurements for the case of the system Zn/D2EHPA, which is a standard test system in reactive extraction. The determinant of the Fisher information matrix was used as a measure of the expected information obtained from the experiments as a function of apparatus geometry. Design parameters like the organic and inorganic phase volumes and the interfacial area between them have been optimized by maximizing the information obtained in each experiment. The results lead to an ideal geometry for such an apparatus, and show that significant improvement compared to current common practice is possible.     

以煤基直接液化油和甲醇为原料生产FS-300系列车用汽油的技术研究

在汽油机燃料的替代技术中,FS(非石油)系列车用汽油以其节能、环保和良好的动力性能受到各方人士的关注。本文介绍了以稳定化处理的煤基直接液化油为主要原料,同甲醇及其衍生物复配后制得了FS-300系列车用汽油,同时对该油品理化指标、行车及排放进行了试验,取得了初步成果。