Fluid Catalytic Cracking Unit Research Articles

Integrated Hybrid Modelling and Surrogate Model-Based Operation Optimization of Fluid Catalytic Cracking Process

Fluid Catalytic Cracking (FCC) is one of the most important conversion processes in oil refineries, widely used to convert high-boiling, high-molecular-weight hydrocarbon components from crude oil into more valuable products like gasoline and diesel. Advanced simulation and optimization technologies are critical for improving the operational efficiency and economic performance of the FCC process. First-principles-based simulators rely on parameter estimation and are computationally intensive, making them unsuitable for online optimization. In recent years, with the development of deep learning, data-driven models have made significant progress in FCC modeling. However, due to their black-box nature and difficulty with extrapolation, they are rarely used for optimization. To bridge this gap, we propose an integrated framework that combines hybrid modeling and surrogate model-based optimization. This approach combines plant and simulation data to train a multi-task learning prediction model, which then serves as a surrogate for operational optimization. Validated on a large-scale FCC unit in southern China, the model predicts product yields with an error margin of under 4.84% for all products. Following optimization, yields of LNG, gasoline, and diesel rose by an average of 0.10 wt%, 1.58 wt%, and 1.05 wt%, respectively, resulting in a 3.67% increase in product revenues. This highlights the substantial potential of this framework for industrial applications.

Application ICP-OES to Multielement Analysis on Plastic Waste and Blends with Vacuum Gas Oil: Developing a Sample Preparation Protocol

This paper introduces a new methodology for a routine metal analysis of plastic waste (PW) and PW blended with petroleum feedstock such as vacuum gas oil and VGO (PW/VGO). For such purposes, recycled polyethylene and polypropylene plastic were selected to mimic the potential feeds to be integrated at the Fluid Catalytic Cracking unit (FCC) to produce valuable products. Elements such as P, Ca, Al, Mg, Na, Zn, B, Fe, Ti, and Si were included in the method development. Different sample preparation methods were evaluated, such as microwave-assisted acid digestion (MWAD) and dry/wet ashing, followed by a fusion of the ash with lithium borate flux. Some PW homogenization pretreatments, such as cryogenic grinding and hot press molding, were also covered. The finding of this work suggests that MWAD with HNO3 and H2O2 is adequate for both types of samples and is the quickest sample preparation; however, the sample needed to be homogenized, and recoveries for Si and Ti may be biased for PW due to the limited solubilities of these elements in the nitric acid media. Carbon removal is required before fusion sample preparation and analysis due to the amount of carbon in PW samples. The sample needed to be homogenized for wet ash fusion but not for the pre-ash (dry) method. A benefit to the damp ash pretreatment is that the ash for the sample was created in the same crucible used for fusion digestion, avoiding material loss during sample management. Fusion from wet ash or carbon removal allowed for better acid solubility for Si and Ti in PW. The results of the PW samples evaluated matched well with those of both sample preparation methodologies. For most elements, precision was <10% regardless of the sample preparation; however, Fe and P had some variation using wet ash fusion, possibly due to contamination in an open digestion system or variation due to being close to the method limit of quantification (LOQ). The methodology reported here is robust enough to be implemented as routine analysis in any laboratory facility.

Research on Denoising Algorithm of Standpipe Pressure Signal in FCC Device Based on Tortuosity and Denoising Intensity.

The pressure signal of the standpipe in the regeneration device for the catalytic cracking reaction is commonly used as a basis for equipment fault diagnosis. The device operates in environments of high temperature, strong vibration, and high flow rate. The standpipe pressure signal is easily interfered with by noise, making it difficult to extract pressure characteristics. In this study, a signal denoising algorithm based on pressure curve tortuosity and denoising intensity is proposed. A power spectrum threshold vector is utilized to filter the pressure in the circulating standpipe, and the denoising intensity and tortuosity after denoising are calculated. Taking the ratio of noise reduction intensity and tortuosity as the objective function, the noise reduction scheme of the pressure signal at different heights of the standpipe is determined. The denoised pressure signals are reconstructed, and the characteristic pressure signals of the circulating standpipe are extracted. The results indicate that the method suppressed the noise, enhanced the significance of characteristic parameters, and improved the accuracy of the fault diagnosis in the FCC units.

Spray characteristics of steam-assisted oil atomization in Y-jet nozzles

Twin-fluid atomizers, valued for handling viscous fluids and high operating loads, are extensively used in combustion processes and oil refineries. In the latter scenario, internal mixing nozzles are employed in fluid catalytic cracking units for oil dispersion using steam as the dispersing medium. While steam-assisted atomization studies often focus on flue gas analysis, the associated steam/oil internal mixing process and the spray droplet dynamics lack proper investigation. Accordingly, this work explores the Y-jet nozzle performance for oil atomization using steam, aiming to determine favorable conditions for obtaining a stable spray with fine droplet distribution. This analysis is accomplished by characterizing the mixing chamber pressure, investigating the spray boundary instabilities using high-speed images, and exploring the spray droplet size using the shadowgraphy technique. Work relevance relies on performing experiments at industrially representative conditions, characterized by the similarity of important dimensionless numbers. Additionally, the nozzle design is optimized by varying key geometric parameters. The nozzle geometry and the operating condition impact on the steam-assisted atomization performance and spray behavior constitutes the main findings of this work. The outcomes highlight the relevance of the fluid dynamics investigation for optimized nozzle performance, involving a balance between spray stability and fine droplet distribution generation.

Properties analysis of catalyst particles during stripper distributor fault in industrial fluid catalytic cracking unit

Particle attrition is prevalent in fluid catalytic cracking (FCC) process, and severe particle attrition threatens the steady operation of FCC units. In this study, the processes of attrition and dealing in industrial FCC unit were investigated, and the relationship between particle physical properties and fault source was analyzed. The results showed that the most frequent particle sizes of the attrited equilibrium catalyst and the spent catalyst were 48.85 μm and 55.21 μm, respectively. The replacement of attrited catalyst by equilibrium catalyst with higher mechanical strength could alleviate the catalyst attrition problem, and the most frequent particle size of the catalyst remained at 75.81 μm after experiencing attrition. When the replacement rate reached 66.83 %, catalyst loss was reduced and the stability of FCC unit operation was significantly improved. This study would contribute to a deeper understanding of the particle abrasion and fragmentation behavior in different environments in industrial FCC units.

Efficient prediction framework for large-scale nonlinear petrochemical process based on feature selection and temporal-attention LSTM: Applied to fluid catalytic cracking

Data-driven modeling plays a vital role in petrochemical industry, especially fluid catalytic cracking (FCC). However, the long operational cycles, large-scale measurements, multivariate data, and intricate temporal correlations in FCC units may lead to the problem of low prediction accuracy when only use a single time series data-driven modeling neural network such as long short-term memory (LSTM) network. To address these challenges, an effective prediction framework is proposed that integrates LSTM network with extreme gradient boosting (XGBOOST)-based feature selection and temporal-attention (TA) mechanisms. XGBOOST is applied to filter features related to the predictive variables in order to eliminate redundant variables. TA mechanisms within an LSTM network is used to capture the relevant historical time steps of the current moment. The results of our efficient prediction framework, applied to FCC process and three additional petrochemical processes, have proven to be superior to other methods.

Roles of Catalysts and Feedstock in Optimizing the Performance of Heavy Fraction Conversion Processes: Fluid Catalytic Cracking and Ebullated Bed Vacuum Residue Hydrocracking

Petroleum refining has been, is still, and is expected to remain in the next decades the main source of energy required to drive transport for mankind. The demand for automotive and aviation fuels has urged refiners to search for ways to extract more light oil products per barrel of crude oil. The heavy oil conversion processes of ebullated bed vacuum residue hydrocracking (EBVRHC) and fluid catalytic cracking (FCC) can assist refiners in their aim to produce more transportation fuels and feeds for petrochemistry from a ton of petroleum. However, a good understanding of the roles of feed quality and catalyst characteristics is needed to optimize the performance of both heavy oil conversion processes. Three knowledge discovery database techniques—intercriteria and regression analyses, and artificial neural networks—were used to evaluate the performance of commercial FCC and EBVRHC in processing 19 different heavy oils. Seven diverse FCC catalysts were assessed using a cascade and parallel fresh catalyst addition system in an EBVRHC unit. It was found that the vacuum residue conversion in the EBVRHC depended on feed reactivity, which, calculated on the basis of pilot plant tests, varied by 16.4%; the content of vacuum residue (VR) in the mixed EBVRHC unit feed (each 10% fluctuation in VR content leads to an alteration in VR conversion of 1.6%); the reaction temperature (a 1 °C deviation in reaction temperature is associated with a 0.8% shift in VR conversion); and the liquid hourly space velocity (0.01 h-1 change of LHSV leads to 0.85% conversion alteration). The vacuum gas oil conversion in the FCC unit was determined to correlate with feed crackability, which, calculated on the basis of pilot plant tests, varied by 8.2%, and the catalyst ΔCoke (each 0.03% ΔCoke increase reduces FCC conversion by 1%), which was unveiled to depend on FCC feed density and equilibrium FCC micro-activity. The developed correlations can be used to optimize the performance of FCC and EBVRHC units by selecting the appropriate feed slate and catalyst.

Effect of regenerated standpipe flow pattern on catalyst transport in fluid catalytic cracking unit

Standpipe is a pipeline that constitutes one of the components in the downstream portion of the catalyst circulation loop in a fluid catalytic cracking (FCC) unit, facilitates catalyst transportation between reactor and regenerator. This study measured pressures of the regenerated standpipe on a 1.0 Mt/a FCC unit to elucidate the underlying cause of the observed catalyst transportation. The results indicated that multiple flow patterns coexist within the standpipe, rather than a single dense-phase flow. The characteristic parameters of the static and dynamic pressure were intimately connected to the aforementioned flow patterns. The dynamic pressure data indicated that pressure dominant frequency and amplitude could employed in the identification of flow patterns. The packed bed flow had a pressure frequency ranging from 0 to 3.3 Hz, and a dominant frequency amplitude of 0.8, 1.8 and 2.2 Hz, allowed diagnosis of poor catalyst transport. The study demonstrated that the standpipe structure and catalyst mass flow rate were the key factors affecting gas-solid flow degassing by allowing for multiple flow patterns in the standpipe. The influence of aeration on the flow patterns was also discussed here, with an improper aeration rate resulting in reaction temperature fluctuations ranging from 0.5 to 23 °C.

Feasibility study of a process for the reduction of sulfur oxides in flue gas of fluid catalytic cracking unit using the riser reactor

In this work, a new process for achieving the recovery of elemental sulfur by utilizing a fluidized catalytic cracking (FCC) riser reactor for SOx treatment (FCC-DeSOx) is proposed. The process leverages the high temperatures and hydrocarbon concentrations in the FCC riser reactor to convert SOx into H2S. Subsequently, H2S, along with the cracked gas, is processed downstream to produce sulfur. Thermodynamic analysis of the key reduction reactions in the FCC-DeSOx process revealed that complete conversion of SOx to H2S is feasible in the dry gas (hydrogen-rich) prelift zone, as well as the upper and lower zones of the riser, upon achieving thermodynamic equilibrium. Experimental studies were conducted to replicate the conditions of these reaction zones using a low concentration of hydrogen gas as the reducing agent. Through process optimization, investigation of the minimum reaction time, and kinetic studies, the potential of this method for the complete reduction of SOx was further confirmed.

An experimental study on the effect of interstage inlet gas on separation performance of two-stage series cyclone separators

Cyclone separators generally operate in multi-stage series to improve gas-solid separation efficiency under high concentration condition. The two-stage series cyclone separators in Fluid Catalytic Cracking unit further require the interstage inlet gas. This paper experimentally studied the effect of the interstage inlet gas on separation performance of two-stage series cyclone separators. A ϕ130mm interstage inlet pipe was installed at the interstage connecting tube between industrial-sized two-stage series ϕ1000mm cyclone separators in the experimental setup. Experiments were conducted at inlet velocities of Vin = 10–20 m/s and concentration of Cin = 10 g/m3, with interstage inlet gas ratios of U = 0–20%. Silica powder with a median diameter of 10.1 μm was used. Results indicate that interstage inlet gas decreases separation efficiency and increases particle run-off loss due to the change of the optimized operation parameters, specifically inlet gas rate and inlet concentration. A prediction model was proposed to provide guidance for potential industrial applications.

Modeling and optimizing gas solid distribution in fluidized beds

In fluidized bed reactors, uniform distribution of gas and solids is critical to achieve the desired hydrodynamic and kinetic performance. For FCC units, Technip Energies uses a proprietary distributor design to terminate both reactor risers and spent catalyst lift lines to distribute the exiting gas-solid stream into a fluidized bed.In Technip Energies' Resid FCC unit, air and spent catalyst are distributed from an upward flowing stream into a catalyst bed for coke combustion on catalyst. Proper distribution is key to achieve a uniform coke burn and an even temperature profile throughout the bed. In PropyleneMax™ Catalytic Cracking (PMcc™) technology, the reactor riser also terminates in a fluidized bed, requiring proper distribution of the hydrocarbon vapor and solid mixture into the reactor bed, which is key to providing adequate contact for further cracking to valuable products. This paper discusses Technip Energies' gas-solid distribution technology and the recent work performed to develop an improved distributor for use as a riser termination device in both the PMcc reactor and the RFCC regenerator to achieve improved performance. The use of CFD modeling to screen and evaluate the initial concepts and optimize the final selected concept are presented here. The performance matrices used to quantify the benefits of the optimized distributor design with respect to the existing one in the reactor application are highlighted, showing the benefits of improved gas solid distribution on hydrodynamic and kinetic performance. The paper presents a systematic approach to develop a novel industrial device using physics-based computational tools.

Direct production of olefins from waste plastic using a pyrolysis and fluid catalytic cracking integrated process: Part 1. study on the production and analysis of waxy oil obtained using a new type of a fluidized bed reactor

The ultimate aim of this research is to produce ethylene and propylene directly from waste plastic. To achieve this, we designed a new cracker having a fluidized bed reactor (FBR) and a fluid catalytic cracking (FCC) unit. The FBR produces oil in vapor phase, and the FCC unit transforms the vapor into olefins. As a first step toward achieving the research goal, the current study conducts pyrolysis of low-density polyethylene using a new pyrolysis process having a FBR. By understanding characteristics of pyrolysis oils obtained in this study, it becomes possible to determine its suitability as FCC feed and its relationship with olefin productivity. The current investigation focused on the effects of vapor residence time, reaction temperature, and type of fluidizing medium on yield and composition of oil. The results showed that the waxy oil yield depended highly on reaction temperature, reaching a maximum of about 95 wt%. The sum of yields of n-alkenes and n-alkadienes, which are favorable for producing olefins when catalytically cracked in the FCC unit, reached 82 wt%. SIMDIS analysis, which determines the boiling point range distribution of oil, revealed strong effects of reaction temperature and residence time on the carbon numbers of the waxy oil.

Experimental study on flow characteristics of gas–solid two-phase flow in inclined pipes

In a fluid catalytic cracking unit, inclined pipes are mainly used for particle transportation and to maintain the pressure balance between the reactor and regenerator. In this experimental inclined pipe device, the characteristics of gas–solid two-phase flow were studied by measuring and analyzing the dynamic pressure and particle concentration parameters in different flow states. Corresponding relationships between pressure fluctuation and particle concentration on the one hand and flow patterns on the other were discovered. These were used for the quantitative identification of flow patterns. Measurement data from an analysis of bubble and particle velocities in an inclined pipe revealed a critical mass flow rate, Gs, in the mutual transformation of different particle flow patterns. The critical mass flow rate Gsc1 of lean-phase and dense-phase flows was 149 kg/(m2·s). The critical mass flow rate Gsc2 of packed-bed and dense-phase flows was 240 kg/(m2·s). This study enriches the basic theoretical knowledge on flow patterns in inclined pipes and provides a theoretical basis for the adjustment of inclined pipe operation in industrial fluid catalytic cracking units.

Fluidized catalytic cracking with novel emulsified feeding for increasing light oil yield and reducing additional CO2 emission

The fluid catalytic cracking unit (FCCU) is widely used in the processing of heavy oil. Fast and sufficient vaporization of heavy oil can maximize the light oil yield and reduce the coke yield. However, the inferior quality generally makes the heavy oil difficult to be vaporized. Unvaporized oil remaining on the catalyst surface will lead to high coke yield and subsequently high carbon dioxide emissions in the regenerator. The novel emulsified feeding technique can achieve secondary atomization of oil droplet through micro-explosion, which can reduce the droplet diameter and enhance the droplet vaporization. Computational Fluid Dynamics (CFD) simulation was performed to investigate the effect of emulsified feeding on the droplet vaporization and cracking reaction in the FCC riser reactor. It was found that when the reaction temperature is constant, the emulsified feeding can promote the droplet vaporization and cracking reaction. The average vaporization ratio can be improved by 1.2%-1.7%, and the light oil yield can be improved by 0.6%-0.8% compared to the conventional atomized feeding. The volume fraction of droplet near the side wall is largely reduced. The additional carbon emissions produced by unvaporized oil can therefore be reduced in the regenerator. In addition, the emulsified feeding technique will not have great impact on solids fluidization and pressure balance in the riser. The probability of micro-explosion of emulsion droplets is further discussed with respect to its effect on the vaporization and cracking reaction. The maximum light oil yield can be obtained with micro-explosion probability of 85%.

CO2 capture and hydrogen generation from a solar-assisted and integrated fluid catalytic cracking process: Energy, exergy, and economic analysis

The fluid catalytic cracking (FCC) process transforms heavy wastes into lighter, more valuable (naphtha, light olefins and gases) products. However, the unit's byproducts contain a large quantity of CO2, which contributes to global warming. As a result, the purpose of this research was to increase the production of valuable products such as light olefins, naphtha, and hydrogen while reducing environmental impacts using the water gas shift reaction, with sensitivity analysis for three parameters (riser height, FCC feed temperature, and inlet naphtha mass flow). As a result of increasing the riser height, the output of light olefins (45%) and gases (32%) increased. Furthermore, the amount of hydrogen produced increases with a decrease in riser height (about 6%) and an increase in inlet naphtha mass flow (about 8%). Energy and exergy assessments were also carried out. It was determined that FCC had the lowest exergy destruction with a contribution of 23 MW when compared to its energy usage of 172 MW. The cooler, on the other hand, was one of the process's most energy-consuming (25%) and damaging (26%). As a result, this technique can lessen environmental effects by absorbing 125 tons of CO2 every hour and producing 3484 kg/h of hydrogen. Economic evaluations were also undertaken, and the results revealed that the cooler has the lowest exergoeconomic factor (1%) while the FCC unit contributes the most (95%). The fractionator column is also the most expensive device in the whole process.

Soyabean oil processed in fluid catalytic cracking unit

Soyabean oil processed in fluid catalytic cracking unit

Integration of Encoding and Temporal Forecasting: Toward End-to-End NOx Prediction for Industrial Chemical Process.

Forecasting NOx concentration in fluid catalytic cracking (FCC) regeneration flue gas can guide the real-time adjustment of treatment devices, and then furtherly prevent the excessive emission of pollutants. The process monitoring variables, which are usually high-dimensional time series, can provide valuable information for prediction. Although process features and cross-series correlations can be captured through feature extraction techniques, they are commonly linear transformation, and conducted or trained separately from forecasting model. This process is inefficient and might not be an optimal solution for the following forecasting modeling. Therefore, we propose a time series encoding temporal convolutional network (TSE-TCN). By parameterizing the hidden representation of the encoding-decoding structure with the temporal convolutional network (TCN), and combining the reconstruction error and the prediction error in the objective function, the encoding-decoding procedure and the temporal predicting procedure can be trained by a single optimizer. The effectiveness of the proposed method is verified through an industrial reaction and regeneration process of an FCC unit. Results demonstrate that TSE-TCN outperforms some state-of-art methods with lower root mean square error (RMSE) by 2.74% and higher R2 score by 3.77%.

Co-processing of organic fraction from groundnut shell biocrude with VGO in FCC unit to produce petrochemical products

This research work explores the transformative potential of biomass leading to sustainable production of biocrude and its utilization in refinery and petrochemical sector for reducing reliance on fossil fuels. In this study, groundnut shell biomass was thermally converted in a customized continuous semi pilot auger reactor in temperature range of 400–700 °C. The optimum temperature for maximizing biocrude was studied, and detailed chemical analysis revealed that biocrude contains hydrocarbons and alcohols with a calorific value of 29 MJ/kg. Furthermore, this study demonstrates the performance of the FCC (Fluid Catalytic Cracking) catalyst and feedstock (H-T- VGO (Hydrothermal vacuum gasoline oil) & Biocrude) in a laboratory-scale utilizing ACE R + MM (Advanced Cracking Evaluation - Residue and Metals Management) unit under predetermined temperatures (515 °C, 525 °C) and a fixed cat-to-oil weight ratio (CTO = 6 w/w). The organic phase and FCC feedstock in different weight ratios from 5 to 20 wt % were blended. There are marginal changes in the yields of dry gas, LCO (light cycle oil) and HCO (heavy cycle oil), with significant increase in the yields of LPG (liquified petroleum gas) and gasoline. Bottoms have been reduced, and coke formation has been adjusted. However, this process requires prudent blending and temperature choices, with future recommendations including improvement in the quality of biocrude to enhance the yields of both LPG and gasoline along with reduced coke formation.

Attention-based early warning framework for abnormal operating conditions in fluid catalytic cracking units

Fluid Catalytic Cracking Unit (FCCU) is a critical processing technology in the oil refining industry, playing a vital role in energy efficiency and environmental protection. However, FCCU often encounters various abnormal operating conditions, leading to safety hazards, downtime, and reduced production efficiency. Early warning of these abnormal conditions is crucial but challenging due to high noise, strong hysteresis, and class imbalance problems. To tackle these challenges, a novel and universal attention-based framework called AEW-AOC (Attention-based Early Warning for Abnormal Operating Conditions) is specifically designed for FCCU applications. The proposed AEW-AOC framework incorporates three key components: (1) a Self-Correlation Denoiser (SCD) module is proposed to exploit spatiotemporal data correlation to effectively reduce noise; (2) a Convolutional Long Short-Term Memory (Conv-LSTM) module is employed to address the issue of strong hysteresis by capturing temporal variation features of process parameters; (3) an Anomaly Pattern Attention (APA) module is proposed to enhance the distinguishability of abnormal operating conditions based on clustering results from historical abnormal instances. Extensive experiments demonstrate the effectiveness and superiority of the proposed AEW-AOC framework, particularly in practical applications. Specifically, the AEW-AOC framework obtains an impressive fβ score of 91.00% on LIC201, 90.45% on LIC202, and 90.64% on LIC801. The proposed AEW-AOC framework shows great potential in enhancing safety, reducing downtime, optimizing efficiency, promoting sustainability, and expanding its applicability beyond FCCU. Its proactive and versatile nature makes it a valuable tool for improving industrial processes and driving advancements in the field of abnormal operating condition detection and prevention.

A hybrid soft sensor for key product yield of FCC unit based on deep learning framework driven by data and process mechanism

The model for online prediction of product yield embedded in the optimization and control framework has the potential to improve the profits of fluid catalytic cracking (FCC) units. In this work, a hybrid soft sensor model is developed to predict key product yield in commercial FCC units. The deep learning framework based on semi-supervised learning is driven by data and process mechanism to construct the hybrid model with a double-layer structure. Moreover, process simulation strategy is utilized for key input variable selection of the hybrid model to ensure model reliability. The hybrid model is compared to a pure data-driven model in terms of accuracy and trend consistency of model predictions. The results demonstrate that the hybrid model exhibits a superior prediction performance. This work suggests that the hybrid model can drive innovation and industrial practice in the optimization and control of FCC units.