Fluid Catalytic Cracking Reactor Research Articles

Study on the flow and collision characteristics of catalyst particles in FCC reactor

Fluid Catalytic Cracking (FCC), a typical fluidization technology, faces serious issues of catalyst particle attrition and loss. Attrition is an important cause of catalyst loss. Due to the small particle size and complex flow process inside the reactor，it is difficult to conduct experimental research on it. The flow, collision and attrition characteristics of catalyst in the reactor are still unclear. This study established a geometric model of a catalytic cracking unit and used CFD-DEM bidirectional coupling numerical simulation method to study the flow and collision characteristics of catalyst particles in the catalytic cracking unit. The result indicate that particles collide with the wall most frequently， with an average collision frequency of 141,501.89 Hz. The particle wall collision frequencies above the nozzle, at the top of the riser, and in the cyclone separator are the highest, with an average collision frequency of 244.90 Hz, 1441.2 Hz, and 3571.15 Hz, respectively. Strong single collisions and slight continuous collisions of large size particles often occurred in the device. For small particles, the difference in strength between each collision within the device is not significant.

A coupling model of fluid catalytic cracking and diesel hydrotreating processes to study the effects of reaction temperature on the composition of diesel

The coupling optimization between different plants was the most difficult and key problem in refineries. To accurately describe the effective transfer of material flow information between Fluid Catalytic Cracking (FCC) and Diesel Hydrotreating (DH) processes and realize the coupling simulation for these processing units in refineries, a coupling model of FCC and DH processes using a fractionation tower simulation system was established to calculate the hydrocarbon compositions of diesel based on the Structure Oriented Lumping (SOL) method. The fractionation tower simulation system developed by MATLAB software was used to divide the molecular composition matrix of FCC product into the molecular composition matrices of dry gas, liquefied petroleum gas, gasoline, diesel, and oil slurry. The molecular composition matrix of diesel contained 73, 69, 183, 121 and 743 structural vectors representing paraffins, olefins, naphthenes, aromatics and non-hydrocarbon molecules, respectively. The fractionation ratios of the hydrocarbon group compositions with carbon numbers between 5 and 12 in the molecular composition matrix of gasoline and diesel were calculated. The effective transmission of material flow in the FCC and DH processes was accurately expressed by the transmission of the molecular composition matrix of diesel obtained by the fractionation tower simulation system. The effects of FCC and DH reaction conditions on the hydrocarbon compositions of diesel were calculated at the molecular level by the FCC-DH process coupling model. Through the FCC-DH process coupling model using a fractionation tower simulation system, the transformation laws of hydrocarbon and non-hydrocarbon molecules in different devices could be revealed to provide guidance for reducing the content of polycyclic aromatic hydrocarbons and sulfur in diesel, optimizing operating conditions and controlling product quality indicators.

Identification of combustion regularities of fuel mixtures from Azolla biomass, goat manure biochar and goat manure bio-oil for FCC furnace

Fluid catalytic cracking (FCC) is a method of cracking vegetable oils into simpler fractions and green fuel oils. One component of the FCC system is the FCC furnace. The FCC furnace is where the combustion process occurs and provides high heat transfer throughout the FCC system, especially for heating the reactor. The reactor temperature is the catalyst cracking temperature. The cracking temperature of the catalyst depends on the feed oil used in the cracking process, such as crude palm oil at 450‒550 °C or crude bio-oil at 300 °C. The fuel for heating an FCC furnace is usually coal. To reduce coal, we use a mixture of Azolla microphylla biomass with biochar and bio-oil from goat manure. The aim of this study was to analyze the mixture of Azolla microphylla biomass with biochar and bio-oil from goat manure to obtain sufficient furnace temperature to heat the FCC reactor, perform analytical calculations to obtain the volume of flue gas formed from the combustion reaction. We conducted two experiments; the first experiment used a mixture of 1 kg of Goat Manure Biochar (GMBC) with 0.5 kg of Azolla microphylla and the second experiment used a mixture of one kg of GMBC with 0.5 kg of Azolla microphylla plus 300 ml of Goat Manure Bio-oil (GMBO). A fuel mixture of one kilogram GMBC with 0.5 kg Azolla is not effective in combustion because the maximum temperature in the furnace is 177 °C but the fuel mixture of one kg GMBC, 0.5 kg Azolla and 300 ml GMBO has a furnace temperature of 472.75 °C, which can heat the stripper up to 313.25 °C so that cracking can occur in the raw bio-oil. Analysis of combustion results showed an increase in total CO2 volume from experiment one and experiment two of 0.966

Study on efficient utilization of light cycle oil with combined process

ABSTRACT A combined process of hydrotreating, fractionating, solvent extraction, and fluid catalytic cracking (FCC) was proposed to improve the added value of light cycle oil (LCO). In the process, hydrotreating LCO (HLCO) was divided into light and heavy fractions by fractionating. The bicyclic and tricyclic aromatics in the heavy fraction of HLCO were extracted to produce chemical products by solvent extraction. The raffinate oil and the light fraction of HLCO, rich in saturated hydrocarbons and monocyclic aromatic hydrocarbons, were processed to produce high-octane gasoline by FCC. According to the results, the combined process solved the problem of polycyclic aromatic hydrocarbons of HLCO being challenging to be cracked in FCC reaction, reduced the yield of dry gas and coke by 43.01 wt%, reduced the yield of diesel with low added value by 32.33 wt%, and optimized the product structure. In other words, the process makes efficient use of the aromatic and nonaromatic components in LCO.

A molecular-level coupling model of fluid catalytic cracking and hydrotreating processes to improve gasoline quality

A molecular-level Fluid Catalytic Cracking (FCC)-Gasoline Hydrotreating (GH) process coupling model was established to guide the optimization of the hydrocarbon compositions in gasoline based on the Structure Oriented Lumping (SOL) method. 96 FCC reaction rules and 24 GH reaction rules were formulated, and a reaction network containing about 120,000 reactions was constructed. In order to establish the FCC-GH process coupling model, the effective transfer of composition information between the two processes was realized through the molecular composition matrix of gasoline. The molecular composition matrix of gasoline was obtained according to the classification rules of the molecular composition matrix of FCC products. The conversion laws of hydrocarbon molecules in gasoline were investigated by tracking their generation paths and reaction paths. The influences of reaction conditions on the distribution of hydrocarbons in the product gasoline could be calculated quantitatively by the FCC-GH process coupling model at molecular level.

Image-Based Analysis of Dense Particle Mixtures via Mask R-CNN

Powders and their mixtures are elemental for many industries (e.g., food, pharmaceutical, mining, agricultural, and chemical). The properties of the manufactured products are often directly linked to the particle properties (e.g., particle size and shape distribution) of the utilized powder mixtures. The most straightforward approach to acquire information concerning these particle properties is image capturing. However, the analysis of the resulting images often requires manual labor and is therefore time-consuming and costly. Therefore, the work at hand evaluates the suitability of Mask R-CNN—one of the best-known deep learning architectures for object detection—for the fully automated image-based analysis of particle mixtures, by comparing it to a conventional, i.e., not machine learning-based, image analysis method, as well as the results of a trifold manual analysis. To avoid the need of a laborious manual annotation, the training data required by Mask R-CNN are produced via image synthesis. As an example for an industrially relevant particle mixture, endoscopic images from a fluid catalytic cracking reactor are used as a test case for the evaluation of the tested methods. According to the results of the evaluation, Mask R-CNN is a well-suited method for the fully automatic image-based analysis of particle mixtures. It allows for the detection and classification of particles with an accuracy of 42.7% for the utilized data, as well as the characterization of the particle shape. Also, it enables the measurement of the mixture component particle size distributions with errors (relative to the manual reference) as low as −2±5 for the geometric mean diameter and −6±5% for the geometric standard deviation of the dark particle class of the utilized data, as well as −8±4% for the geometric mean diameter and −6±2% for the geometric standard deviation of the light particle class of the utilized data. Source code, as well as training, validation, and test data publicly available.

Eight-lumped kinetic model for Fischer-Tropsch wax catalytic cracking and riser reactor simulation

Wax produced during Fischer-Tropsch synthesis (FTS) has no sulfur, nitrogen and aromatic contents and could be an attractive material to produce high quality transportation fuels by means of fluid catalytic cracking reaction. The kinetic modeling and riser reactor simulation are urgently needed. However, most of the current models in this field are based on crude oil feedstock which can not rigorously reflect the features of FTS wax catalytic cracking, especially the aromatization of the cracked light olefins for aromatic gasoline components. The effects of operating conditions on the catalytic cracking performance of FTS wax are investigated in a riser reactor with an industrial β-zeolite based catalyst. An eight-lumped (including paraffins, olefins, naphthenes and aromatics in gasoline, liquefied petroleum gas, dry gas, FTS wax and coke) kinetic model is developed for product selectivity description and riser reactor simulation in FTS wax catalytic cracking. The theoretical prediction is in good agreement with the experimental data. The modeling work is very helpful in reactor scale-up and operating condition optimization of the process.

Gas-solid-liquid reactive CFD simulation of an industrial RFCC riser with investigation of feed injection

The feed injection zone involving gas–solid-liquid mixing, vaporization and reaction plays an important role in fluid catalytic cracking reactors. Our previous cold-model simulation indicated that a modification from the conventionally upward feed injection scheme to a downward one improves the oil-catalyst matching. This work aims to investigate the effects of such downward feed injection on the reaction behaviors through three-phase reactive simulation of an industrial riser. A twelve-lump kinetics and vaporization of liquid oil were considered in a multiphase Eulerian model with the energy-minimization multi-scale model. The predicted solids flux, temperature, and solids concentration were compared with experimental data. The simulation showed that the downward injection with an angle of around 30° and suitable mounting position helps improving the yield of gasoline and LPG and mitigating adhesion of the coking layer to the wall. We expect such an approach sheds light on the optimization of the three-phase chemical reactors.

Thermal and catalytic pyrolysis of waste polypropylene plastic using spent FCC catalyst

Waste polypropylene plastic (WPP) is an enormous volume of plastics in the landfill in Nigeria. It causes serious environmental problems, such as reduced landfill space and pollution. We made WPP plastic undergo pyrolysis using a batch reactor subjected to temperatures variation of 300 °C, 350 °C, 375 °C, 400 °C, and the spent fluid catalytic cracking (FCC) catalyst used were 5, 7.5, and 10 wt% catalyst. We heated the reactor at a rate of 15 °C/min. until it reaches the pyrolysis temperature of 400 °C at atmospheric pressure. We investigated the influence of the FCC catalyst, reaction temperatures, and catalyst to plastic ratio. We characterized the pyrolysis liquid oil using density, pour point, API gravity, flash point, viscosity, calorific value, carbon residue, ATSM distillation, and GC–MS. The thermal pyrolysis produced maximum liquid oil (83.3 wt%) with gases (13.2 wt%), and char (3.0 wt%), while the catalytic pyrolysis using 0.1 catalyst to plastic ratio decreased the liquid oil yield (77.6 wt%), and char (2.7 wt%), with an increase in gases (19.7 wt%). The GC–MS results of the catalytic pyrolysis of liquid oil showed that the liquid fractions comprised a wide range of hydrocarbon, mainly distributed within C4 to > C17. The paraffin, olefins, naphthalene, and aromatics yield were 30.83%, 44.6%. 19.44%, and 5.13%, respectively. The liquid oil’s fuel properties were like that of gasoline and diesel. • The liquid oil yield from thermal (83.3 wt%) and that of catalytic (77.6 wt%) pyrolysis. • The liquid fractions comprises a wide range of hydrocarbons from C 4 -C 17 . • The liquid oils fuel properties were comparable to that of gasoline and diesel.

A new composite consisting of Y zeolite and ZrO2 for fluid catalytic cracking reaction

In fluid catalytic cracking (FCC) unit, basic nitrogen species in heavy oil result in the poison of Y zeolite acid sites and the loss of heavy oil conversion. To solve this issue, Y/ZrO2 composites are prepared by a two-stage crystallization method. The composite bears a uniform particle size and micro-mesoporous hierarchical structure. The Zr–O–Si chemical bonds are observed between Y zeolite and ZrO2 in Y/ZrO2 composites, which result from the incorporation of Zr species into the framework of Y zeolite. Compared to the mechanical mixture of Y zeolite and ZrO2, composites have abundant Lewis acid sites, which capture basic nitrogen species to protect the acid sites over Y zeolite. It endows a higher heavy oil conversion (increased by 2 wt%) to the Y/ZrO2 composites in the catalytic cracking of heavy oil with high-basic nitrogen compounds. It is worth noting that the hierarchical pore structure of Y/ZrO2 composite inhibits coke deposition. These results are important to propose a new FCC catalyst to catalytic crack heavy oil with high amount of bulky basic nitrogen compounds.

An Overview of Light Olefins Production via Steam Enhanced Catalytic Cracking

Steam thermal cracking is an established technology for the production of light olefins, such as ethylene and propylene. The shift to lighter, ethane-based feeds means that propylene production from steam crackers will be lower than the corresponding ethylene production. Therefore, alternative technologies have to be developed to produce more propylene to make up for the shortfall from steam cracking. This review looks at the steam catalytic cracking technology, which combines both catalytic cracking and steam cracking to maximize the production of light olefins. This review looks at the effect of catalyst and technology applied in fluid catalytic cracking reactors to enhance light olefins production. The influence of reaction conditions and the reaction mechanism are also presented. The graphical abstract shows the feed and steam being fed into the FCC unit from which light olefins and gasoline are produced as the desired products.

Effect of vacuum gas oil hydrotreating reactor on multiple reactors and hydrogen network

Abstract The inlet temperature of the Vacuum Gas Oil (VGO) hydrotreating reactor of a refinery is analyzed with the integration of multiple series reactors and hydrogen network considered. The effect of the inlet temperature (T1) on hydrogen sinks/sources and the product output is analyzed systematically based on the simulation of the series reactors, including VGO hydrotreating reactor, hydrocracking reactor, fluid catalytic cracking reactor and visbreaking reactor. The general relation between the Hydrogen Utility Adjustment (HUA) and multiple pairs of varying sinks and sources is deduced, and correlations between varying streams and T1 are linearly fitted. Based on this, the quantitative equation between HUA and T1 is derived, and corresponding diagram is constructed. The T1 corresponding the minimum hydrogen consumption is identified to be 345 °C.

Transformations of FCC catalysts and carbonaceous deposits during repeated reaction-regeneration cycles

Transformations of an industrial zeolite-based fluid catalytic cracking (FCC) catalyst and its coke deposits during regeneration following FCC reactions of a representative refinery stream are investigated.

Fluid catalytic cracking technology: current status and recent discoveries on catalyst contamination

ABSTRACT The fluid catalytic cracking (FCC) technology is one of the pillars of the modern petroleum industry which converts the crude oil fractions into many commodity fuels and platform chemicals, such as gasoline. Although the FCC field is quite mature, the research scope is still enormous due to changing FCC feedstock, gradual shifts in market demands and evolved unit operations. In this review, we have described the current status of FCC technology, such as variation in the present day feedstocks and catalysts, and particularly, great attention is paid to the effects of various contaminants of the FCC catalysts of which the latter part has not been sufficiently documented and analyzed in the literature yet. Deposition of various contaminants on cracking catalyst during FCC process, including metals, sulfur, nitrogen and coke originated from feedstocks or generated during FCC reaction constitutes a source of concern to the petroleum refiners from both economic and technological perspectives. It causes not only undesirable effects on the catalysts themselves, but also reduction in catalytic activity and changes in product distribution of the FCC reactions, translating into economic losses. The metal contaminants (vanadium (V), nickel (Ni), iron (Fe) and sodium (Na)) have the most adverse effects that can seriously influence the catalyst structure and performance. Although nitrogen and sulfur are considered less harmful compared to the metal contaminants, it is shown that pore blockage by the coking effect of sulfur and acid sites neutralization by nitrogen are serious problems too. Most recent studies on the deactivation of FCC catalysts at single particle level have provided an in-depth understanding of the deactivation mechanisms. This work will provide the readers with a comprehensive understanding of the current status, related problems and most recent progress made in the FCC technology, and also will deepen insights into the catalyst deactivation mechanisms caused by contaminants and the possible technical approaches to controlling catalyst deactivation problems.

Stress Analysis of FCC Reactor Vessel using SP Test and FEA

Fluid Catalytic Cracking (FCC) Unit is a large-pressure vessel that converts heavy crude oil, which cannot be distilled, into light crude oil. With the growing interest in renewable energy sources due to environmental regulations, various studies investigating FCC Units are ongoing. The catalytic reactor in FCC Unit is a large structure that generates prolonged high pressure, leading to changes in the properties of the material during operation. Therefore, stress analysis must be conducted based on the application of the actual mechanical properties. In cylindrical thin structures such as the FCC reactor, a tensile test is difficult to perform, warranting the need for Shear Punch (SP) test that uses a small specimen. The properties were utilized in finite element analysis. To determine the boundary and load conditions needed for stress analysis, the operational conditions of the reactor and the conditions for internal pressure of ASME Code regulation were used to evaluate the stress.

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.

Numerical investigation of heavy fuel droplet-particle collisions in the injection zone of a Fluid Catalytic Cracking reactor, part II: 3D simulations

This study investigates the collisions between heavy gasoil droplets and solid catalytic particles taking place at conditions realized in Fluid Catalytic Cracking reactors (FCC). The computational model utilizes the Navier-Stokes equations along with the energy conservation and transport of species equations. The VOF methodology is used in order to track the liquid-gas interface, coupled with a dynamic local grid refinement technique in order to minimize the computational cost. Phase-change phenomena, as well as catalytic cracking surface reactions (2-lump scheme) are taken into account. In this paper, the numerical model is extended to investigate the droplet-particle collision process in three dimensions. In order to save computational resources, only half of the droplet is investigated, by imposing symmetry conditions. Firstly, single droplet-catalyst collisions are simulated and compared against the corresponding ones provided by 2D axisymmetric simulations and afterwards, the model is applied for the characterization of the collision dynamics between a single droplet and a particle cluster, i.e. a realistic 3D particle configuration. As the droplet flows through the space between the catalytic particles, important phenomena are observed, such as a) drop levitation due to the formed vapour layer and b) a thin liquid sheet formation, both of which affect the rate of gasoline production, as well as predictions for liquid pore blocking mechanism; a phenomenon frequently observed industrially. Results indicate that gasoline production decreases when the collision target is a particle cluster, instead of same number (as many as in the cluster) single catalysts, as the corresponding contact area decreases.

Numerical investigation of heavy fuel droplet-particle collisions in the injection zone of a Fluid Catalytic Cracking reactor, Part I: Numerical model and 2D simulations

The present paper investigates the collisions between heavy gasoil droplets and solid catalytic particles taking place at conditions realized in Fluid Catalytic Cracking reactors (FCC). The computational model utilizes the Navier-Stokes equations along with the energy conservation and transport of species equations. The VOF methodology is used in order to track the liquid-gas interface, while a dynamic local grid refinement technique is adopted, so that high accuracy is achieved with a relative low computational cost. Phase-change phenomena (evaporation of the heavy gasoil droplet), as well as catalytic cracking surface reactions are taken into account. Physical properties of heavy and light molecular weight hydrocarbons are modelled by representative single component species, while a 2-lump scheme is proposed for the catalytic cracking reactions. The numerical model is firstly validated for the case of a single liquid droplet evaporation inside a hot gaseous medium and impingement onto a flat wall for droplet heating and film boiling conditions. Afterwards, it is utilized for the prediction of single droplet-catalyst collisions inside the FCC injection zone. The numerical results indicate that droplets of similar size to the catalytic particles tend to be levitated more easily by hot catalysts, thus resulting in higher cracking reaction rates/cracking product yield, and limited possibility for liquid pore blocking. For larger sized droplets, the corresponding results indicate that the production of cracking products is not favored, while solid-liquid contact increases. Hotter catalysts promote catalytic cracking reactions and droplet levitation over the catalytic particle, owed to the formation of a thin vapour layer between the liquid and the solid particle.

Role of nickel on vanadium poisoned FCC catalyst: A study of physiochemical properties

Active sites of Fluid catalytic cracking (FCC) catalyst are poisoned during operation in the FCC reactor due to causes including feedstock contaminant metals deposition. This leads to activity, selectivity and increasing coking problems, thereby raising concern to the refiner. This work investigated effect of nickel coexisting with vanadium in the FCC feedstock on the standard FCC catalyst during cracking process, in which destruction of active sites occurs as a result of the metals deposition. Laboratory simulated equilibrium catalysts (E-cats) were studied by XRD, FTIR spectroscopy, N2 adsorption, solid state MAS-NMR, SEM and H2-TPR. Results revealed that vanadium, above a certain concentration in the catalyst, under hydrothermal conditions, is highly detrimental to the catalyst's structure and activity. Conversely, nickel hardly affects the catalyst structure, but its co-presence in the catalyst reduces destructive effects of vanadium. The mechanism of nickel inhibition of vanadium poisoning of the catalyst is discussed.

Effects of mass transfer resistance and coking on yield during fluid catalytic cracking of heavy hydrocarbon fractions

A transient model for an industrial fluid catalytic cracking (FCC) riser is here presented. The FCC riser models of previous researchers were mostly based on the assumption of negligible mass transfer resistance. This assumption reduced the accuracy of the models. In this work, the effects of mass transfer resistance and coking on the yield of FCC reactions were modeled and simulated. A five-lump reaction scheme was used to model the cracking reactions. Catalyst deactivation was modeled based on the exponential decay function. The mass transfer coefficient and the catalyst effectiveness factor were estimated from empirical correlations obtained from literature. The model parameters that were used in this investigation were sourced from the field as well as from literature. The reaction model was solved using COMSOL Multiphysics 4.0. The major difficulty encountered in this investigation was the unavailability of experimental data from which the mass transfer resistance, catalyst effectiveness factor, kinetic constants of the cracking reactions and effective diffusivities of species could be determined. This challenge was overcome by using empirical correlations from literature to estimate the terms. Model data which could not be obtained from the plant were sourced from literature and duly referenced. The proposed model vividly showed that mass transfer resistance significantly affects FCC reactions. Previous models over-predicted the residence time of the riser while under-predicting the over-cracking point of gasoline (the key product). A residence time of 2s and a gasoline yield of 45% were predicted by this model. Key words: Fluid catalytic cracking (FCC), Transient model, mass transfer resistance, catalyst deactivation, Riser models.