Fluid Catalytic Cracking Unit Research Articles

A Review of Modelling of the FCC Unit—Part II: The Regenerator

Heavy petroleum industries, including the Fluid Catalytic Cracking (FCC) unit, are among some of the biggest contributors to global greenhouse gas (GHG) emissions. The FCC unit’s regenerator is where these emissions originate mostly, meaning the operation of FCC regenerators has come under scrutiny in recent years due to the global mitigation efforts against climate change, affecting both current operations and the future of the FCC unit. As a result, it is more important than ever to develop models that are accurate and reliable at predicting emissions of various greenhouse gases to keep up with new reporting guidelines that will help optimise the unit for increased coke conversion and lower operating costs. Part 1 of this paper was dedicated to reviewing the riser section of the FCC unit. Part 2 reviews traditional modelling methodologies used in modelling and simulating the FCC regenerator. Hydrodynamics and kinetics of the regenerator are discussed in terms of experimental data and modelling. Modelling of constitutive parts that are important to the FCC unit, such as gas–solid cyclones and catalyst transport lines, are also considered. This review then identifies areas where the current generation of models of the regenerator can be improved for the future. Parts 1 and 2 are such that a comprehensive review of the literature on modelling the FCC unit is presented, showing the guidance and framework followed in building models for the unit.

A Review of Modelling of the FCC Unit–Part I: The Riser

Heavy petroleum industries, including the fluid catalytic cracking (FCC) unit, are useful for producing fuels but they are among some of the biggest contributors to global greenhouse gas (GHG) emissions. The recent global push for mitigation efforts against climate change has resulted in increased legislation that affects the operations and future of these industries. In terms of the FCC unit, on the riser side, more legislation is pushing towards them switching from petroleum-driven energy sources to more renewable sources such as solar and wind, which threatens the profitability of the unit. On the regenerator side, there is more legislation aimed at reducing emissions of GHGs from such units. As a result, it is more important than ever to develop models that are accurate and reliable, that will help optimise the unit for maximisation of profits under new regulations and changing trends, and that predict emissions of various GHGs to keep up with new reporting guidelines. This article, split over two parts, reviews traditional modelling methodologies used in modelling and simulation of the FCC unit. In Part I, hydrodynamics and kinetics of the riser are discussed in terms of experimental data and modelling approaches. A brief review of the FCC feed is undertaken in terms of characterisations and cracking reaction chemistry, and how these factors have affected modelling approaches. A brief overview of how vaporisation and catalyst deactivation are addressed in the FCC modelling literature is also undertaken. Modelling of constitutive parts that are important to the FCC riser unit such as gas-solid cyclones, disengaging and stripping vessels, is also considered. This review then identifies areas where current models for the riser can be improved for the future. In Part II, a similar review is presented for the FCC regenerator system.

The reduction of FCCU afterburning through process optimization and regenerator revamping

Operating the fluid catalytic cracking unit (FCCU) in afterburning conditions can increase the regenerator temperatures above the metallurgical design leading to mechanical failures of the cyclones and plenum chamber. This paper presents the methodology applied in a commercial FCCU to investigate the afterburning causes and the technical solutions that can be implemented to reduce the afterburning. Thus, by evaluating the regenerator temperature profile, regenerator as-build design, and the internals mechanical status, it was concluded that the main cause of afterburning was the non-uniform distribution and mixing of air and catalyst. The industrial results showed that optimizing the catalyst bed level, stripping steam, reaction temperature, and equilibrium catalyst (e-cat) activity reduced the afterburning by 39%. Other process parameters such as feed preheat temperature, slurry recycling, and excess oxygen did not significantly influence afterburning because of air and catalyst maldistribution. Revamping the regenerator to assure a symmetrical layout of cyclones reduced the afterburning by 86%, increased the fines retention in FCCU inventory, and provided a better regeneration of the spent e-cat. The reduction of operating temperatures at around 701?C removed the risk of catalyst thermal deactivation, and therefore the e-cat activity was increased by 10.2 wt.%.

Examination of the Causes and Frequency of Fire Hazard in Communities Housing Refinery Flammable Facilities: A Case Study of PHRC

Fire hazards regardless of their immediate or remote cause(s), always have very serious consequences whenever they occur. This paper examines the causes and frequency of fire hazards in the host communities of Port Harcourt Refinery Company (PHRC) flammable materials, to establish the causes and frequency of fire outbreaks in such facilities as the Crudeoil tanks, Crude Distillation Unit (CDU), Fluid Catalytic Cracking Unit (FCCU), Naphtha Hydrotreating Unit (NHU), and suggesting measures to reduce such practices. The research was sorted via an intensive literature review alongside the administration of a well-structured questionnaire. A total of seventy questionnaires with sixty returned adequately filled giving a percentage response of 85.7%. The responses were analyzed using computer-based software (SPSS) and the result was presented in percentages and Relative Importance Indices (RII). The result showed among others that the reoccurring communal practice around PHRC that lead to fire hazard is bush burning (RII=0.91). Other common practices that lead to fire hazards are; Arson and incineration of refuse at proximity to combustible elements. The result also shows that there is no fire enlightenment within this environment. Thus, based on the findings the following are recommended; regulation and supervisory committees be set up and empowered to guide against the act of bush burning around PHRC flammable facilities. Fire prevention measures and enlightenment should be organized within the communities surrounding PHRC, and also the point where PHRC flammable facilities are stored or located within the communities should be well designated so that people can easily see and consequently avoid any activity that can instigate the eruption of fire outbreak.

Modelling, control and supervisory optimization of generalized predictive control in catalytic cracking reactor

Abstract As gasoline demand increases, the efficiency of operation of Fluidized Catalytic Cracking Unit (FCCU) becomes paramount importance. In this paper, a dynamic model for FCCU is simulated and integrated with yield model in order to estimate the yield of products namely gasoline, light gases and coke. Conventional PI controllers are designed for the control of reactor and regenerator temperature. Since, the complete reaction occurs in a very short duration, the controllers are tuned so as to achieve shorter settling time and minimum overshot. Further in order to increase the yield, optimization of FCCU using Generalized Predictive Controller (GPC) at supervisory level is attempted. Through optimization of objective function, the GPC will provide optimized set point for the PI controller in order to maintain maximum gasoline yield.

Simulation of methanol synthesis by hydrogenation of carbon dioxide recovered from combustion gases of Fluid Catalytic Cracking Unit of Abadan Refinery

Simulation of methanol synthesis by hydrogenation of carbon dioxide recovered from combustion gases of Fluid Catalytic Cracking Unit of Abadan Refinery

Kinetic modeling for the catalytic cracking of tires pyrolysis oil

The parameters of a 6-lump kinetic model for the catalytic cracking of tire pyrolysis oil (TPO) in conditions of the industrial fluid catalytic cracking (FCC) unit have been computed. The experiments have been carried out in a riser simulator reactor, on a commercial equilibrium catalyst at the following conditions: 500–560 °C; catalyst/oil ratio (C/O), 3–7 gcat gTPO-1; and reaction time, 1–10 s. The most significant catalytic steps for conversion levels below 80% are those in which the heavy cycle oil (HCO) lump is involved, either cracked to form light cycle oil (LCO), naphtha, liquefied petroleum gases (LPG), dry gas or condensed to coke. For higher levels of conversion, LCO and naphtha lump over-crack causing exponential increases in the yields of LPG, dry gas and coke. It should be highlighted the high yield of naphtha obtained (48 wt%) for a conversion of 90% at 530 °C. It is also remarkable the low deactivation level by coke deposition, since the coke formed on the acid sites of the catalyst is not much condensed. The results are of great interest for the design or reactors ad hoc for the catalytic cracking of TPO in conditions similar to those of industrial FCC unit, as well as for its feeding to a commercial unit within the strategy involved in the Waste Refinery.

Effect of flow patterns in the recirculation catalyst standpipe on the performance of FCC high-efficiency regenerator

In this work, the flow patterns of the recirculation catalyst standpipe in an industrial fluid catalytic cracking unit (FCCU) were investigated based on the dynamic pressure, and their effects on the regeneration process were analyzed. First, the dynamic pressure along the standpipe was systematically measured and used to determine the flow patterns. The results demonstrated that the frequency, amplitude, and standard deviation of the dynamic pressure were correlated with various fluid patterns. Meanwhile, gas leakage was detected near the slide valve. Based on the dynamic pressure behavior, two flow pattern models, which involved bubbling fluidized flow, transitional packed bed flow and packed bed flow, were established to interpret the impacts on the regeneration parameters. The results indicated that the developed model was consistent with precious observations regarding an industrial FCCU. This work contributes to a deeper understanding of the flow patterns in industrial luid catalytic cracking standpipes.

Practical Approaches towards NOx Emission Mitigation from Fluid Catalytic Cracking (FCC) Units

There appears to be consensus among the general public that curtailing harmful emissions resulting from industrial, petrochemical and transportation sectors is a common good. However, there is also a need for balancing operating expenditures for applying the required technical solutions and implementing advanced emission mitigation technologies to meet desired sustainability goals. The emission of NOx from Fluid Catalytic Cracking (FCC) units in refineries for petroleum processing is a major concern, especially for those units located in densely populated urban settings. In this work we strive to review options towards cost-efficient and pragmatic emissions mitigation using optimal amounts of precious metal while evaluating the potential benefits of typical promoter dopant packages. We demonstrate that at present catalyst development level the refinery is no longer forced to make a promoter selection based on preconceived notions regarding precious metal activity but can rather make decisions based on the best “total cost” financial impact to the operation without measurable loss of the CO/NOx emission selectivity.

Method and apparatus for forming electrode catalyst layer by electrospray method

The conversions of oxygenated compounds of bio-oils (alcohols, phenols and aromatic ethers) on a equilibrium FCC catalyst were studied at 500 °C during 60 s in a fixed bed laboratory reactor. Methanol, phenol and 2,6-dimethoxyphenol were dissolved in water and 1,2,4-trimethoxybenzene in benzene at 5 %wt. Identical experiments were performed over inert SiC. Conversions were very different, the highest one being that of 1,2,4-trimethoxybenzene (95.7 %wt.), followed by 2,6-dimethoxyphenol (75.0 %wt.), methanol (60.8 %wt.) and phenol (54.9 %wt.). Deoxygenation in all the reactants was from dehydration and decarboxylation. The highest yield of hydrocarbons (47.1 %wt.) and coke (16.0 %wt.) were from 1,2,4-trimethoxybenzene, which, together with methanol, yielded mainly aromatics in the gasoline range. On the contrary, phenol and syringol yielded C4-hydrocarbons with high content of olefins. The highest amounts of oxygenated compounds were produced by 2,6-dimethoxyphenol. The thermal conversions were similar to the catalytic ones in the only case of 1,2,4-trimethoxybenzene, but much lower with the other reactants. In comparison to the catalytic experiments, thermal tests yielded much more hydrocarbons with 1,2,4-trimethoxybenzene, and oxygenated compounds with 2,6-dimethoxyphenol, than the other reactants. These tests could help in the prediction of specific contributions by these reactants if bio-oils are co-processed in FCC units or upgraded over acidic catalysts.

A solvent deasphalting dearomatization (SD-A2) process for heavy oil upgradation

A two stage solvent deasphalting dearomatization (SD-A2) process has been conceptualized for upgrading heavy oils. In the first stage, pentane, heptane and refinery untreated/ treated naphtha streams (Light Naphtha (LN), Heavy Naphtha (HN) & Raffinate Naphtha (RN)) were investigated for deasphalting performance. To enhance the deasphalting, spent catalyst from Fluid Catalytic Cracking Unit (FCCU) is used in the first stage which showed increase deasphalted oil (DAO) and also pitch yields up to 2 wt%. In the second stage, six polar solvents viz. sulfolane, N-methylpyrrolidone (NMP), tri-ethylene glycol, tetra-ethylene glycol, furfural and N-formylmorpholine (NFM) have been analyzed for dearomatization. The phase equilibria behaviour of these six potential polar solvents was investigated, including the interaction behaviour of their components with heavy oil components using ternary phase diagrams at ambient conditions, before selecting the most suitable solvent for dearomatization. Based on the phase equilibria data, distribution coefficient, selectivity, and performance index (PI) of the solvents was also estimated. For the oils which have C6–C15 carbon range, the universal quasi-chemical UNIQAC model was used to predict the liquid–liquid equilibria (LLE) and solvent NMP gave highest performance index for the high carbon number feedstock. The effects of solvent types and solvent to feed ratio on the deasphalting performance was also investigated. Finally, the DAO obtained at each stage was fed to a fluid catalytic cracking (FCC) bench-scale unit and the results showed significant improvement in gasoline yields up to 5 wt% and the coke was also lowered to 2 wt%.

Al ion-exchanged USY in FCC catalyst for high LPG yield

Refineries, especially fluid catalytic cracking (FCC) units are required to increase propylene production because of changing demand from fuels to chemicals in recent years. We have found a promising FCC catalyst for such demand. The FCC catalyst with Al ion-exchanged USY zeolite (catalyst (Al)) has indicated the higher LPG yield without decreasing in the activity. The catalyst (Al) would be suppressing hydrogen transfer reactions between products or intermediates. Moreover, the olefins in the gasoline would be over-cracked to LPG over catalyst (Al) because of strong acidity of Al ion-exchanged USY.

Investigation of the hydrodynamics in the regenerator of fluid catalytic cracking unit integrated by chemical looping combustion

Oil refineries are responsible for 4–6% of global CO2 emissions, and 20–35% of these emissions released from the regenerator of Fluid Catalytic Cracking (FCC) units, which are the essential units for the conversion of heavier petroleum residues (vacuum gas oil) into more valuable products. Chemical looping combustion (CLC) has been recently proposed to mitigate the CO2 emissions released from the regenerator of FCC units with a lower energy penalty. However, a detailed experimental and modelling investigation is still necessary in order to identify the hydrodynamics in the regenerator of chemical looping combustion integrated with fluidised catalytic cracking (CLC-FCC). A computational fluid dynamic (CFD) study was conducted to understand the hydrodynamic behaviours of gas-solid two-phase flow in the regenerator of the CLC-FCC unit, based on a three-dimensional multiphase model (Eulerian-Eulerian) with the kinetic theory of granular flow.The results provide a useful insight into regenerator hydrodynamics, in terms of oxygen carrier modified FCC catalysts and FCC coke distribution profiles, in the regenerator of CLC-FCC. The conventional drag models (Syamlal-O'Brien and Gidaspow) predict a bed density profiles of a dense phase (250–300 kg/m3) at the dense phase (0–0.25 of h/H), and a dilution phase from h/H = 0.25 to 0.50 of regenerator. The bed density profile is indistinguishable from the industrial data provided for conventional FCC regenerators. The fluidisation gas (CO2) passes through the centre of the regenerator where the fluidisation gas splits the catalyst particles from the centre to the walls, to create a dilute particle phase in the centre and a dense particle-phase near the wall, which is one of the characteristic flow regimes in circulating fluidised bed reactors. The particles in the centre demonstrate an upward flow trend with a particle velocity above 3.0 m/s while the dense particles near the wall tend to go down with relatively low particle velocity of <0.5 m/s, which creates vortexes and a non-uniform particle distribution in the regenerator. The distribution of the fluidising gas provides better mixing of solid particles in the entrance and the optimisation of the superficial gas velocities (1.0 m/s) to create a distributed flow regime with developed vortexes through the dense and dilute phases. Furthermore, the laminar and turbulent flow models demonstrated no significant differences in terms of axial bed density profile in the regenerator of the CLC-FCC concept. These findings demonstrated that the hydrodynamics of catalysts in the CLC-FCC regenerator successfully predicted with CFD modelling and the prediction results aligned well with the conventional FCC regenerator.

Optimization Study on Increasing Yield and Capacity of Fluid Catalytic Cracking (FCC) Units

The fluidized catalytic cracking (FCC) unit is the primary production unit for gasoline and olefins in refineries. Improving product yield and processing capacity is closely related to the economic benefits of refineries. In this paper, we use the Aspen HYSYS software to model the mechanism of an 800 kt/a FCC unit in China. The simulation of the FCC unit based on the 21-lump models and the simulation results are in good agreement with the actual factory production data. Then we find out the optimization method to improve the product yield and processing capacity through the model research. The results of the study indicate the following optimization plans: when keeping the riser outlet temperature (ROT) in the range of 535~545 °C, it can increase the yield of gasoline and liquefied petroleum gas (LPG) by up to 5%; when keeping the riser outlet temperature (ROT) in the range of 510~520 °C, it can increase the yield of gasoline and diesel by up to 0.5%; the optimal ROT of control temperature should be 530 °C when ensuring the same gasoline yield and increasing processing capacity, it can increase the feed rate by 14.3% which in turn increases gasoline production. Through the above plans, the refinery can achieve the production goals of yield and capacity. Therefore, the refinery can get more profits.

Simulation of an Industrial Carbon Black Reactor Using Collision Kinetics

Purpose: Objective of the work was to test efficacy of the proposed flame chemistry and collision kinetics for prediction of process parametres through determination of the effect of basic process parameters on yield (which includes but not limited to grade of carbon black produced).&#x0D; Methodology: The research methodology in this work was simulation of an industrial Carbon Black Reactor based on reaction kinetics from flame chemistry which assumes that primary particle formation and particle growth is strictly by collision of molecular nuclei with gas molecule as proposed by the collision theory. Decant oil from the Fluid Catalytic Cracking Unit (FCCU) of the Warri Refinery and Petrochemical Company Limited of Nigeria represented by naphthalene was used as feedstock in the simulation while methane gas is the fuel for combustion needed to attain the reaction temperature.&#x0D; Findings: Results showed an excellent quantitative prediction of trends by models. Qualitative predictions gave far higher parameter values, something easily attributable to the excessively high values of kinetic data used for model testing. &#x0D; Recommendation: The simplifying assumptions of these models completely ignored microscopic phenomena such as interface mass and heat transfer and other similar processes. Consequently, the model can be improved upon by introducing some of these processes as identified.

Fluid Catalytic Cracking handbook: An expert guide to the practical operation, design, and optimization of FCC units

This new and improved edition focuses on providing practical information and tools that engineers can use to maximize the profitability and reliability of their fluid catalytic cracking operations. The updated chapters and new content deliver expertise and know-how to an industry that faces significant cost cutting in capital expenditure and R&D, along with the retirement of technical specialists who are taking existing knowledge out of the industry with them. This Handbook provides a valuable easy-to-understand resource for both experienced and inexperienced engineers and anyone else associated with the FCC process. This book gives those who need a quick reference, and gives those who are developing their skills and knowledge trusted information that will help them succeed with their projects. This title features common examples that will enable engineers to achieve increased unit savings. It is updated with the latest process technologies for handling residue and deep hydrotreated feedstock. It features a new chapter discussing refractory lining, providing an introduction to the different refractories employed in FCC units, examples of various refractory linings and associated anchors, installation techniques as well as some guidelines for proper drying and curing refractory lining. There is a new troubleshooting chapter, increasing the practical application of the book, along with new visual references to operation optimization. About the author: Reza Sadeghbeigi is President of RMS Engineering, Inc. a Houston, Texas based engineering firm providing high-level technical expertise in the area of fluid catalytic cracking (FCC) and related processes. Reza has 35 years of hands-on FCC experience in the refining industry, focusing on technical services, troubleshooting, process design, and project management, including major FCC revamps. A licensed Professional Engineer (P.E.) in Texas and Louisiana, Reza has published technical papers and produced industry seminars on refining and catalytic cracking operations and conducted numerous client customized FCC training courses and public seminars. This is the only practical approach, with tools and techniques for those with FCC responsibilities to help maximize the profitability and reliability of fluid catalytic cracking operations. This title is updated throughout, with new material focusing on latest developments, the shift to using FCC to process lower quality crudes, and new applied material on troubleshooting. It provides a reference for both experienced engineers who need a quick reference, as well as providing those who are developing their skills and knowledge with access to trusted information that will help them succeed in their projects.

Opportunities for utilizing waste cooking oil in crude to petrochemical process: Novel process design, optimal strategy, techno-economic analysis and life cycle society-environment assessment

The efficient utilization of waste cooking oil (WCO) in petrochemical and high-quality gasoline production could reduce food safety issues and boost the new energy industry's sustainable development. The co-processing of WCO, vacuum gas oil, and light cycle oil (LCO) by the fluid catalytic cracking unit could achieve process integration, which exhibits promising economic prospects for manufacturing large amounts of low-cost petrochemicals. Herein, we proposed a novel process, i.e., hierarchical LCO hydrotreating combined with two-stage riser catalytic cracking processes (HTMP-plus). Based on industrial test data, the process model of HTMP-plus was first developed on the Aspen HYSYS Petroleum Refining platform and optimized operating parameters were conducted. In this novel process, lighter LCO fractions were directly recycled to the second riser reactor, and heavier LCO fractions were fed into the selective hydrotreating unit. This strategy intensified the conversion of WCO and LCO, reduced hydrogen consumption, and improved the economic benefit. Furthermore, the life cycle society-environment evaluation was performed. Compared with the conventional HTMP process, the HTMP-plus process could produce 5% more propylene and high-quality gasoline for every ton of mixed feedstock and provide up to a 31% increase in net present value. Moreover, the HTMP-plus process consumes approximately 5% less non-renewable energy and discharges 2% less CO2 equivalent and 16% less wastewater based on one-million-USD dollars total output value.

Real-time refinery optimization with reduced-order fluidized catalytic cracker model and surrogate-based trust region filter method

Since its initial development in the 1980′s, Real-Time Optimization (RTO) has been widely appreciated as an efficient way to optimize process decision variables and improve economic performance of refineries. RTOs consist of nonlinear optimization models with hundreds of thousands of equations, which are built within equation-oriented (EO) modeling platforms. With increasing size and complexity of RTO applications, there is increased demand for improved optimization strategies. To address this demand, surrogate models for complex refinery units have been embedded within the general EO framework for RTO. Moreover, the recent trust region filter (TRF) optimization strategy allows great flexibility in the choice of surrogates, while ensuring convergence to the optimum of the rigorous RTO model. This study considers this approach for a real-world refinery. The Petrobras S.A. RECAP unit in Mauá, Brazil runs an RTO refinery model with an Aspen RTO optimizer to maximize the profit within two hour cycles. To reduce the computational burden, we embed a reduced model (RM) to replace the detailed (truth) model for the residue fluid catalytic cracking (RFCC) unit, and implement a TRF optimization strategy. The TRF driver is written in Python and integrates with the RFCC truth model, the Aspen-EO RECAP model, and the Aspen RTO optimizer. The approach is illustrated on three real-world scenarios in order to demonstrate the effectiveness and efficiency of this RM-based optimization strategy.

Data-based design of inferential sensors for petrochemical industry

Inferential (or soft) sensors are used in industry to infer the values of imprecisely and rarely measured (or completely unmeasured) variables from variables measured online (e.g., pressures, temperatures). The main challenge, akin to classical model overfitting, in designing an effective inferential sensor is the selection of a correct structure of the sensor. The sensor structure is represented by the number of inputs to the sensor, which correspond to the variables measured online and their (simple) combinations. This work is focused on the design of inferential sensors for product composition of an industrial distillation column in two oil refinery units, a Fluid Catalytic Cracking unit and a Vacuum Gasoil Hydrogenation unit. As the first design step, we use several well-known data pre-treatment (gross error detection) methods and compare the ability of these approaches to indicate systematic errors and outliers in the available industrial data. We then study effectiveness of various methods for design of the inferential sensors taking into account the complexity and accuracy of the resulting model. The effectiveness analysis indicates that the improvements achieved over the current inferential sensors are up to 19%.

Robust optimization of stiff delayed systems: application to a fluid catalytic cracking unit

We apply a robust steady state optimization method for stiff delay differential equations to the economic optimization of a fluidized catalytic cracking unit. Stiff systems of differential equations appear in this case due to the different time scales in the gas and fluid phase. Delays result from the catalyst hold-ups in the standpipes connecting riser and regenerator. We show that the proposed robust optimization method can cope with stiffness and delays. Moreover, the proposed method is capable of simultaneously optimizing the process parameters and tuning controller parameters.