Fluid Catalytic Cracking Model Research Articles

Investigation of Ionic Liquids as Extraction Solvents for Separating Bicyclic Aromatic S/N-Compounds from FCC Diesel

To improve the quality of fluid catalytic cracking (FCC) diesel, ionic liquids (ILs) were used as promising neoteric solvents to extract bicyclic S/N-compounds (quinoline and 1-benzothiophene) from FCC model oil. In addition to the thermodynamic properties, including solvent capacity and selectivity, physical properties such as viscosity and thermal stability are also considered as important factors in the IL screening process. 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2MIM][NTF2]) was selected as the most suitable extraction solvent by the COSMO-RS model, and the accuracy of this model was verified based on the collected experimental data. Liquid–liquid equilibrium experiments were performed to study the effects of the initial quinoline and 1-benzothiophene concentrations, mass solvent ratio, extraction stages, and the presence of other aromatics on the extraction efficiency. Then, the extraction mechanism and the differences in the extraction effects for the quinoline and 1-benzothiophene systems were explored by quantum chemical calculation and molecular dynamics simulation. The consistency between experiments and theoretical calculation indicates that the electrostatic interaction is the main reason for the difference in the extraction efficiency between the quinoline and 1-benzothiophene systems.

CoMoS/modified-kaolin bi-functional hydrodesulfurization-olefin skeletal isomerization catalyst for FCC naphtha hydro-upgrading

Aiming at developing a bifunctional selective hydrodesulfurization (HDS) - olefin skeletal isomerization catalyst for fluid catalytic cracking (FCC) naphtha hydro-upgrading, in this article we present an acid-assisted dealumination method, the acid-modified kaolin (AMK-850-27) with tailored porosity and acidity and CoMoS bi-functional catalysts CoMo/AMK-850-27 was obtained. The catalytic performance was assessed with model FCC naphtha that is composed of thiophene (300 mg/kg) and 1-hexene (20%) in heptane. Compared with two catalysts used γ-Al2O3 and HZSM-5 as supports, CoMoS catalyst prepared with AMK-850-27 displayed compromise catalytic performance: balanced HDS activity and selectivity, high skeletal isomerization activity and low cracking activity, and excellent octane number preservation performance. This can be attributed to the following reasons: (i) AMK-850-27 possesses micro-meso-macro porosities and appropriate Brönsted acidity that can benefit skeletal isomerization activity but depress cracking activity; and (ii) The olefin isomers are more difficult to be hydrogenated than the corresponding linear terminal ones due to the steric effect of the branched olefins. This investigation providesa novel route to achieving deep desulfurization, appropriate olefin reduction and octane number preservation for FCC naphtha upgrading, acidic support with meso-macro-porosity can benefit olefin skeletal isomerization and the HDS selectivity but lower hydrocarbon cracking activity.

Molecular level analysis on performance of diameter expanding reactor to improve gasoline quality in FCC process

A molecular level model for Fluid Catalytic Cracking (FCC) process was established based on the Structure-Oriented-Lumping (SOL) method to investigate the effects of the diameter expanding reactor on the product distribution. According to the molecular composition characteristics of feed oil, 24 structural increments were adopted to construct a molecular matrix containing 4539 molecules. Combined with the SOL reaction rules, a reaction network consisting of 118,272 reactions was established using MATLAB. The contents of 266 molecules in gasoline and 1189 molecules in diesel oil were calculated using the molecular level models of diameter expanding reactor and conventional reactor. The olefins content in gasoline, which is the summarization of 83 olefins molecules, increased as the reaction temperature went up. Compared with the conventional reactor, the ratio of isopentane to pentene in the diameter expanding reactor increased from 1.38 to 2.59 and the ratio of toluene to methylcyclohexane increased from 2.69 to 3.94. The model illustrated that the diameter expanding reactor could enhance the hydrogen transfer and isomerization reactions from the molecular level to reduce the olefins content and improve the iso-paraffins content in gasoline. The model could describe the molecular level product distribution from the reactor inlet to the outlet.

Development of Fluid Catalytic Cracking Distributed Simulator Based on IEC 61499

Fluid Catalytic Cracking (FCC) is one of the most important process units in oil refining. Operator skill is one of the determining factors for operational success. The operator cannot train his skills at the plant because it will endanger the ongoing process. Operators' skills can be trained through simulation media. This study developed an FCC model IV process simulator to meet these needs. The application of the IEC 61499 standard uses to create simulation models based on IEC 61499 runtime environments (FORTE). Model validation based on reference simulations. The average percentage of error steady under normal operating conditions is 1.63%. Mean Absolute Percentage Error (MAPE) values for changes in the coking factor, atmospheric temperature and feed temperature are 4.40%, 7.26%, and 6.05%, respectively. Modeling of FCC products on 6 components (gas oil, diesel oil, gasoline, light gas, liquid petroleum gas, and coke) was added as a simulation result. Percent of gas oil conversion between simulation results and plant data has an error of 0.12%. The total fraction value of the components of the simulation results is 1.00 for each operating condition. The simulator interface in the form of a human-machine interface (HMI) was developed using Node-RED. Data communication between FCC simulation models on FORTE and HMI on Node-RED uses the Message Queuing Telemetry Transport (MQTT) communication protocol. Implementation of the IEC 61499 standard allows the simulation model to be distributed across several resources. The distribution of resources is done by simulating the FCC process to be run on several FORTE. The FCC simulation model distributed at 2, 4, and 7 resources can reduce memory usage compared to the 1 centralized resource model by 18.0%, 36.0%, and 48.8%.

A new lumping kinetic model for fluid catalytic cracking

In the modeling of fluid catalytic cracking reaction, it is necessary to take slurry as an independent lump due to the great difference between feedstock properties and slurry properties. Based on the commercial data and the reaction mechanism of catalytic cracking, the 8 lumped kinetic model including slurry lump and 7 lumped kinetic model excluding slurry lump were developed combined with the characteristics of the MIP (maximizing isoparaffins) reaction. By means of Fourth-order Runge-Kutta integral method and two-swarm cooperative particle swarms optimization method, the kinetic model parameters were estimated, respectively. The average relative error between commercial data and calculated values, as well as the results of product predictions, indicate that the eight-lumped kinetic model has higher prediction accuracy, and the predicted results of slurry yield are more in line with the actual industrial conditions.

8-Lump kinetic model for fluid catalytic cracking with olefin detailed distribution study

Modeling fluid catalytic cracking (FCC) riser reactors is of significant importance in FCC unit control, optimization and failure detection, as well as development and design of new riser reactors. In this study, kinetic behavior of vacuum gas oil (VGO) catalytic cracking is studied by developing an 8-lump kinetic model to describe the product distribution. The feedstock and products are divided into eight lumps by reasonably simplifying reaction network, including VGO feed, diesel oil and gasoline, LPG, butylenes, propylene, ethylene, light gases, and coke. A time-on-stream non-selective catalytic activity equation is also assumed to model deactivation mechanism. Twenty-seven pairs of model kinetic parameters are estimated using two different optimization methods, namely: non-dominated sorting genetic algorithm II (NSGA-II), and chaotic particle swarm optimization (C-PSO) algorithm. Performances of both optimization methods are compared and C-PSO algorithm is selected as the superior method in terms of computation time and finding the global optimum. In the current research, based on validated estimated parameters of the preferred C-PSO method, the effects of some operating parameters on product yields distribution are investigated and discussed. This model can be used to predict the riser key products and their compositions with high degree of accuracy which may be especially useful for the conventional FCC processes with olefins production streams.

Model Optimization for an Industrial Fluid Catalytic Cracking Riser-regenerator Unit by Differential Evolution Algorithm

A differential evolution (DE) algorithm for determining 16 advanced turning model parameters of a 1.2 million industrial fluid catalytic cracking (FCC) unit modeling by HYSYS 8.4 is presented. Industrial data from a Chinese petroleum refinery were used to develop, train and check the model. Due to FCC complexity, the proposed model is capable of predicting the yield of products based on main operating conditions. The optimized FCC model is used for further optimized analysis of the FCC unit operating conditions based on the maximum of economic benefits. Prediction of the economic benefit of FCC unit increases 917 yuan/h at the optimized operating conditions.

A two‐zone model for fluid catalytic cracking riser with multiple feed injectors

Developments in modeling of the fluid catalytic cracking (FCC) process have progressed along two lines. One emphasizes composition‐based kinetic models based on molecular characterization of feedstocks and reaction products. The other relies on computational fluid dynamics. The aim is to develop an FCC model that strikes a balance between the two approaches. Specifically, we present an FCC riser model consisting of an entrance‐zone and a fully developed zone. The former has four overlapping, fan‐shaped oil sprays. The model predicts the plant data of Derouin et al. and reveals an inherent two‐zone character of the FCC riser. Inside the entrance zone, cracking intensity is highest and changes rapidly, resulting in a steep rise in oil conversion. Outside the entrance zone, cracking intensity is low and varies slowly, leading to a sluggish increase in conversion. The two‐zone model provides a computationally efficient modeling approach for FCC online control, optimization, and molecular management. © 2014 American Institute of Chemical Engineers AIChE J, 61: 610–619, 2015

Poly[bis(p-methyl phenyl) phosphazene] Pervaporative Membranes for Separating Organosulfur Compounds from n-Heptane and Its Surface Functionalization

This work investigates the application of poly[bis(p-methyl phenyl) phosphazene] (PMePP) for separating organosulfur compounds from n-heptane. PMePP was synthesized and characterized by NMR, X-ray photo spectroscopy, thermogravimetric analysis, scanning electron microscopy, and Fourier transformed infrared spectroscopy. Membranes based on PMePP were fabricated and investigated for desulfurization of FCC (fluid catalytic cracking) model gasoline by pervaporation. The effects of operating temperature, feed composition, and feed sulfur content on the performance of PMePP membranes were investigated. The experimental results showed that the PMePP-based membranes are effective for FCC gasoline pervaporative desulfurization. To provide active spots for future grafting modification, the surface functionalization of PMePP was carried out to convert the methyl units into carboxylic units. The surface-functionalized membrane was also investigated for its pervaporation performance, and results showed the increased in enrichment factor and less temperature dependence.

Enhancing FCC gasoline desulfurization performance in a polyphosphazene pervaporative membrane

Nowadays, pervaporation is widely investigated as a promising process in FCC (fluid catalytic cracking) gasoline deep desulfurization, in which the membrane plays a decisive role. In this work, a membrane with high desulfurization performance was initiated and its pervaporation performance was evaluated using FCC model gasoline composed of thiophene and heptane. The membrane was prepared from chlorine incompletely substituted poly [bis (phenoxy) phosphazene] (Cl-PBPP) followed by simple self-crosslinking at room temperature. Compared with previous jobs, the Cl-PBPP is 12times increased in pervaporation separation index. Moreover, via self-crosslinking the trade-off effect is eliminated. The highest enrichment factor and flux of Cl-PBPP membrane for separating thiophene from heptane are 5.6 and 1.38kg/(m2h), respectively. The obtained results are promising for industrial trial.

Using hybrid neural networks in scaling up an FCC model from a pilot plant to an industrial unit

The scaling up of a pilot plant fluid catalytic cracking (FCC) model to an industrial unit with use of artificial neural networks is presented in this paper. FCC is one of the most important oil refinery processes. Due to its complexity the modeling of the FCC poses great challenge. The pilot plant model is capable of predicting the weight percent of conversion and coke yield of an FCC unit. This work is focused in determining the optimum hybrid approach, in order to improve the accuracy of the pilot plant model. Industrial data from a Greek petroleum refinery were used to develop and validate the models. The hybrid models developed are compared with the pilot plant model and a pure neural network model. The results show that the hybrid approach is able to increase the accuracy of prediction especially with data that is out of the model range. Furthermore, the hybrid models are easier to interpret and analyze.

A New Approach to Determining Product Selectivity in Gas Oil Cracking Using a Four-Lump Kinetic Model

A simplified four-lump model for fluid catalytic cracking (FCC) as reported in the literature has been examined. The model, which relates the coke yield to other yields, is important to FCC operation but requires intensive data analyses. In this article, a new methodology that can validate the model and substantially simplify the data treatments is proposed. The method is applicable to both steady-state FCC riser cracking and unsteady-state microactivity tests (MAT). An explicit expression, derived for the coke yield as a function of conversion, is shown to describe the reported data well. The method is independent of the catalyst decay function and the reaction order of gas oil cracking. This enables the model to be applicable to many systems, even noncatalytic pyrolysis. A case study of the model, which uses the proposed method, suggests that for a given feed-catalyst system the relative rates of coke formation from either gasoline or gas oil may be the same for different reactors.