Fluid Catalytic Cracking (FCC) Process Modeling, Simulation, and Control

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%.

The technical and economic analysis of processing and conversion of heavy oil cuts to valuable refinery products

Many of the modern refineries are founded on converting/upgrading the heavy bases of low value to lighter products by higher added value like gasoline, jet fuel and diesel fuel. In this work, some process configurations in heavy refinery cracking, converting and treating are technically and economically evaluated. In this purpose, four process configurations for refinery plants are suggested. These processes are evaluated and analyzed to obtain the most optimal configurations with the aim of achieving the most valuable refinery products. The difference of the processes is in heavy residue conversion and processing. These processes are included the Asphalt Air Blowing Unit (AABU, Type 1), Delayed Coker Unit (DCU, Type 2), Heavy Residue Hydro-Conversion (HRH, Type 3) and Solvent De-Asphalting (SDA, Type 4). The units are common in mentioned refineries cases and just ABU, HCU, DCU, HRH and SDA are different. In economic consideration, the payout period is considered as one of the standard methods of assessing the economic projects and economically estimating them. As results, the highest rate of gasoline is recorded in the refinery type of DCU unit and the highest amount of LPG/C4/C3, kerosene and gasoline production observed in refinery type of HRH unit. The construction of refinery with ABU unit has minimum investment (980 million $) and highest rate of return (19.4).

Gray wolf optimizer with bubble-net predation for modeling fluidized catalytic cracking unit main fractionator

Fluidized catalytic cracking unit (FCCU) main fractionator is a complex system with multivariable, nonlinear and uncertainty. Its modeling is a hard nut to crack. Ordinary modeling methods are difficult to estimate its dynamic characteristics accurately. In this work, the gray wolf optimizer with bubble-net predation (GWO_BP) is proposed for solving this complex optimization problem. GWO_BP can effectively balance the detectability and exploitability to find the optimal value faster, and improve the accuracy. The head wolf has the best fitness value in GWO. GWO_BP uses the spiral bubble predation method of whale to replace the surrounding hunting scheme of the head wolf, which enhances the global search ability and speeds up the convergence speed. And Lévy flight is applied to improve the wolf search strategy to update the positions of wolfpack for overcoming the disadvantage of easily falling into local optimum. The experiments of the basic GWO, the particle swarm optimization (PSO) and the GWO_BP are carried out with 12 typical test functions. The experimental results show that GWO_BP has the best optimization accuracy. Then, the GWO_BP is used to solve the parameter estimation problem of FCCU main fractionator model. The simulation results show that the FCCU main fractionator model established by the proposed modeling method can accurately reflect the dynamic characteristics of the real world.

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.

Geothermal solid waste derived Ni/Zeolite catalyst for waste cooking oil processing

The main aim of this work was to develop a sustainable Ni/Zeolite catalyst derived from geothermal solid waste for waste cooking oil processing. The effects of catalyst concentration and operation temperature on the transesterification process for biodiesel production which used waste cooking oil as feedstock were investigated to determine the optimum biodiesel process condition. Results have shown the synthesized Ni/Zeolite catalyst was granular in shape and crystalline with increased surface area and pore volume, 80.661 m² g^-1, and 0.123 cc g^-1 respectively. Meanwhile, the highest biodiesel yield obtained was 89.4 % at 3 % w/w Ni/Zeolite catalyst addition and 60 °C operating temperature. The reusability of the synthesized catalyst was also investigated, with results showing the biodiesel yield decreasing to 73.3 % after three cycles.

A Model of Catalytic Cracking: Product Distribution and Catalyst Deactivation Depending on Saturates, Aromatics and Resins Content in Feed

The problems of catalyst deactivation and optimization of the mixed feedstock become more relevant when the residues are involved as a catalytic cracking feedstock. Through numerical and experimental studies of catalytic cracking, we optimized the composition of the mixed feedstock in order to minimize the catalyst deactivation by coke. A pure vacuum gasoil increases the yields of the wet gas and the gasoline (56.1 and 24.9 wt%). An increase in the ratio of residues up to 50% reduces the gasoline yield due to the catalyst deactivation by 19.9%. However, this provides a rise in the RON of gasoline and the light gasoil yield by 1.9 units and 1.7 wt% Moreover, the ratio of residue may be less than 50%, since the conversion is limited by the regenerator coke burning ability.

Catalyst/Feedstock Ratio Effect on FCC Using Different Catalysts Samples

The present study is a follow-up to a recent authors contribution which describes the effect of the C/O (catalyst/oil) ratio on catalytic cracking activity and catalyst deactivation. This study, while valuable, was limited to one fluidized catalytic cracking (FCC) catalyst. The aim of the present study is to consider the C/O effect using three FCC catalysts with different activities and acidities. Catalysts were characterized in terms of crystallinity, total acidity, specific surface Area (SSA), temperature programmed ammonia desorption (NH3-TPD), and pyridine chemisorption. 1,3,5-TIPB (1,3,5-tri-isopropyl benzene) catalytic cracking runs were carried out in a bench-scale mini-fluidized batch unit CREC (chemical reactor engineering centre) riser simulator. All data were taken at 550 °C with a contact time of 7 s. Every experiment involved 0.2 g of 1,3,5-TIPB with the amount of catalyst changing in the 0.12–1 g range. The resulting 0.6–5 g oil/g cat ratios showed a consistent 1,3,5-TIPB conversion increasing first, then stabilizing, and finally decreasing modestly. On the other hand, coke formation and undesirable benzene selectivity always rose. Thus, the reported results show that catalyst density affects both catalyst coking and deactivation, displaying an optimum C/O ratio, achieving maximum hydrocarbon conversions in FCC units.

Progress in kinetic predictions for complex reaction of hydrocarbons: from mechanism studies to industrial applications

Kinetic predictions for complex reaction systems of hydrocarbons are theoretically and technologically crucial to the petrochemical industry. Among several proposed kinetic models, a lumping kinetic model is a comparatively simple and developed method wherein a complex system is lumped into several pseudo-components. To acquire more accurate mechanistic information, kinetic models at the mechanistic level are developed, such as single-event kinetic and structure-oriented models. However, the number of kinetic parameters increases exponentially in these methods. Lumping kinetic methods are then reexamined, and kinetic models, such as relumping single-event kinetic methods, bimolecular methods, and special pseudo-component methods, are proposed to simplify the reaction system. Many mathematical methods, such as annealing algorithm or artificial neural networks, have also been developed to solve these complex reaction problems. Although a number of complex intrinsic reaction studies have been introduced, the combination of excellent prediction performances and practical industrial applicability remains a central challenge facing this field. This situation motivated this study, to review the recent development of reaction prediction models and their application in industrial processes. Furthermore, the practical applications of these possible pathways of kinetic predictions for mechanistic studies are addressed.

Recent advances of pore system construction in zeolite-catalyzed chemical industry processes

The kaleidoscopic applications of zeolite catalysts (zeo-catalysts) in petrochemical processes has been considered as one of the major accomplishments in recent decades. About twenty types of zeolite have been industrially applied so far, and their versatile porous architectures have contributed their most essential features to affect the catalytic efficiency. This review depicts the evolution of pore models in zeolite catalysts accompanied by the increase in industrial and environmental demands. The indispensable roles of modulating pore models are outlined for zeo-catalysts for the enhancement of their catalytic performances in various industrial processes. The zeolites and related industrial processes discussed range from the uni-modal micropore system of zeolite Y (12-ring micropore, 12-R) in fluid catalytic cracking (FCC), zeolite ZSM-5 (10-R) in xylene isomerization and SAPO-34 (8-R) in olefin production to the multi-modal micropore system of MCM-22 (10-R and 12-R pocket) in aromatic alkylation and the hierarchical pores in FCC and catalytic cracking of C4 olefins. The rational construction of pore models, especially hierarchical features, is highlighted with a careful classification from an industrial perspective accompanied by a detailed analysis of the theoretical mechanisms.