Hydrodynamics of Riser Units and Their Impact on FCC Operation

Derouin, C.; Nevicato, David; Forissier, M.; Wild, Gabriel; Bernard, J.R.

doi:10.1021/ie970432r

Cited by 56 publications

(89 citation statements)

References 16 publications

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“…Figure 3 shows the concentration profiles along the axial coordinate in the riser. Figure 4 predicts that much of the gas oil conversion occurs in the first 5m of the riser, which is correspondence with other FCC unit riser simulation Berry et al, 2004;Kimm et al, 1996: Martin et al, 1992Theologos and Markatos, 1993;Derouin et al, 1997) and commercial data (Xu et al, 2006). There are a number of reasons for this, First, the bottom zone of the riser has a high catalysts concentration, In addition, this catalysts just have been reintroduced from the regenerator, has high activity than it does at higher axial location in the riser, Further more, the concentration of gas oil vapor is highest at the base of the riser in compared to that at higher axial locations, where reaction and molar expansion decrease the gas oil concentration.…”

Section: Resultssupporting

confidence: 82%

Study of Seven-Lump Kinetic Model in the Fluid Catalytic Cracking Unit

Heydari¹

2010

American Journal of Applied Sciences

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Problem statement:The effective simulation of the Fluid Catalytic Cracking (FCC) operation requires a good understanding of many factors such as, reaction kinetic, fluid dynamics and feed and catalyst effects. Approach: In this model the reactor has been considered as an isothermal riser. The reactions in the riser occur with the fluid and the solids in ideal plug flow. Because of complication of the catalytic cracking mechanism and existence of multi-components in the feed, to decrease the calculation content in the kinetic models, the reactants and products have been considered as a set of hydrocarbons, so these models are called "Lumped Models". Results: To simulate the FCC riser, the seven-lump model involved residual oil, heavy lump, light lump, liquefied petroleum gas, gasoline, dry gas and coke (to predict the feed conversion and the product distribution) has been developed. Conclusion: Simulation studies are performed to investigate the effect of changing various process variables, such as temperature and residence time. Comparison of simulation results with industrial ones shows that the simulation has been achieved accurately.

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Section: Resultssupporting

confidence: 82%

Study of Seven-Lump Kinetic Model in the Fluid Catalytic Cracking Unit

Heydari¹

2010

American Journal of Applied Sciences

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“…A system for the treatment and monitoring of the air quality aided in the maintenance of adequate operational conditions of the CFPU. Control strategies were used [6] with the aid of a PLC. To maintain flow conditions through the CFPU riser in stationary state its operational conditions are computer controlled.…”

Section: Cold Pilot Unitmentioning

confidence: 99%

Uncertainty evaluation by gamma transmission measurements and CFD model comparison in a FCC cold pilot unit

Dantas

Moura

Filho

et al. 2013

Int. J. Metrol. Qual. Eng.

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Abstract. The solid flow in air-catalyst in circulating fluidized bed was simulated with CFD model to obtain axial and radial distribution. Therefore, project parameters were confirmed and steady state operation condition was improved. Solid holds up axial end radial profiles simulation and comparison with gamma transmission measurements are in a good agreement. The transmission signal from an 241 Am radioactive source was evaluated in NaI(Tl) detector coupled to multichannel analyzer. This non intrusive measuring set up is installed at riser of a cold pilot unit to determine parameters of FCC catalyst flow at several concentrations. Mass flow rate calculated by combining solid hold up and solid phase velocity measurements was compared with catalyst inlet measured at down-comer. Evaluation in each measured parameter shows that a relative combined uncertainty of 6% in a 95% interval was estimated. Uncertainty analysis took into account a significant correlation in scan riser transmission measurements. An Eulerian approach of CFD model incorporating the kinetic theory of granular flow was adopted to describe the gas-solid two-phase flows in a multizone circulating reactor. Instantaneous and local gas-particle velocity, void fraction and turbulent parameters were obtained and results are shown in 2 D and 3D graphics.

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“…Since α s,avg is typically larger in the bottom acceleration region and top deceleration region and lowest in the middle fully developed region, fixed mass flow rate requires that the axial average solid velocity vary accordingly as described in Equation 3b. Profiles for gas velocity in Equation 5a can be taken from Martin et al [23] and Derouin et al [7]. In a riser, index n may be around 1/7 and less than 1.0 because of turbulence (Bird et al, [4]).…”

Section: A Hybrid Of Engineering Gas-solid Two-fluid Modelmentioning

confidence: 99%

“…Accurate description of the dynamic for the solid flow is needed to predict the solid void fraction such that active site concentration of the catalyst can be accurately determined to calculate reaction rates in the reactor. Because of the complexity of multiphase flow theory, it appears that the CFD based method is still insufficient to provide accurate prediction of solid fraction profile (Mao,[19]; Mao et al, [20,21]; Das et al, [6,7]). …”

Section: Introductionmentioning

confidence: 99%

An advanced gas—solid flow engineering model for a fluidized bed reactor system

Mao¹,

Tirtowidjojo²

2007

WIT Transactions on Engineering Sciences, Vol 56

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A literature survey shows that there are two approaches to mathematically describe gas-solid two-phase flow and reaction in the fluidized bed reactors. One approach is a very simplistic engineering reactor model, and the other approach is based on a rigorous Computational Fluid Dynamic (CFD) model. Despite significant progress on numerical methods, CPU capacity and performance, and theories describing gas-solid flow, CFD based reacting flow modeling is far from being a routine tool for designing new reactors. Thus, simpler reactor models are still the main method for providing guidance for fluidized bed reactor design and optimization. However, traditional reactor models have considered too many simplifying assumptions that create inconsistencies in the governing equations of the boundary conditions such that it can result in erroneous prediction. In the current paper, an advanced gas-solid two-phase engineering reactor model has been developed for flow, heat transfer and reaction in the riser reactor of a circulating fluidized bed system. In contrast to CFD, this model can use as input parameters the hydrodynamic information obtained from published literature or experimental measurement such as axial and radial profiles for solid volume fraction, gas velocity and gas dispersion coefficient. While the hydrodynamics can be as accurate as measured, this advanced engineering reactor model is also coupled with either simple power law or the most rigorous kinetic models that involve elementary reactions. In this way, we can extract heterogeneous reaction kinetics from pilot plant or production reactor data directly. Model validation with pilot plant data and tracer data for a riser reactor will be presented and the short falls of traditional treatment of engineering fluidized bed reactor models will also be discussed.

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Hydrodynamics of Riser Units and Their Impact on FCC Operation

Cited by 56 publications

References 16 publications

Study of Seven-Lump Kinetic Model in the Fluid Catalytic Cracking Unit

Study of Seven-Lump Kinetic Model in the Fluid Catalytic Cracking Unit

Uncertainty evaluation by gamma transmission measurements and CFD model comparison in a FCC cold pilot unit

An advanced gas—solid flow engineering model for a fluidized bed reactor system

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