Understanding Riser and Downer Based Fluid Catalytic Cracking Processes by a Comprehensive Two-Dimensional Reactor Model

Wu, Changning; Cheng, Yi; Ye, Jin

doi:10.1021/ie800168x

Cited by 23 publications

(17 citation statements)

References 41 publications

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“…A mathematical model was also developed by Arandes et al [22] which is useful for predicting the behavior of FCC units both under steady and unsteady conditions. Wei et al [23] and Wu et al [24] developed kinetic reactor models using different lumping schemes for both riser and downer in fluid catalytic cracking process. Berry et al [25] developed a two dimensional hydrodynamic model and coupled it with the four kinetic lump model for the reactor.…”

Section: Introductionmentioning

confidence: 99%

Parametric Sensitivity Studies in a Commercial FCC Unit

Dasila¹,

Choudhury²,

Saraf³

et al. 2012

ACES

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A steady state model was developed for simulating the performance of an industrial fluid catalytic cracking (FCC) unit which was subsequently used in parametric sensitivity studies. The simulator includes kinetic models for the riser reactor and the regeneration systems. Mass and energy balances were performed for each of these sections and simulation results were compared with the plant data available in the literature. Model predictions were found to be in close agreement with the reported data. Finally this validated model was used for studying the effects of independent variables such as feed preheat temperature (T feed ) and feed flow rate (F feed ) on the unit performance at either fixed regenerated catalyst temp/regenerator temp (T rgn ) or constant reactor outlet temperature (ROT). The catalyst circulation rate (CCR) was automatically adjusted to keep the ROT constant with varying the independent variables feed preheat temperature while the air rate adjusted for keeping the regenerator temperature constant which consequences the dependency of both dependent and independent variables on the unit performance. The air flow rate to the regenerator was also an independent variable during the parametric sensitivity analysis and its effect on FCC performance was investigated at constant T feed , F feed and CCR. Combining all the sensitivity analysis, it has been found to increase gas oil conversion and product yields by 5 to 6 percent with decrease of say, 10 K, in the feed preheat temperature (T feed ) and corresponding increase in air rate (F air ) and catalyst circulation rate (F rgc ) at constant reactor outlet temperature (ROT) and regenerated catalyst temperature (T rgc ).

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Section: Introductionmentioning

confidence: 99%

Parametric Sensitivity Studies in a Commercial FCC Unit

Dasila¹,

Choudhury²,

Saraf³

et al. 2012

ACES

View full text Add to dashboard Cite

show abstract

“…[28]). In the iterative solution algorithm [28], the hydrodynamics model was coupled into the mass and energy conservation equations and solved iteratively.…”

Section: The Reactor Model For Single Riser or Downermentioning

confidence: 99%

“…[28]). In the iterative solution algorithm [28], the hydrodynamics model was coupled into the mass and energy conservation equations and solved iteratively. The mass and energy conservation equations were stated as a series of second-order partial differential equations (PDE), which were successfully solved by the finite element method (FEM).…”

Section: The Reactor Model For Single Riser or Downermentioning

confidence: 99%

“…The 14-lump kinetic model [28,29] was chosen in this work to describe the complex chemical reactions in the FCC process for better description of the feedstock composition, reaction mechanisms, and product distribution. Lumps include five levels: heavy fuel oil (HFO, >350°C), light cycle oil (LCO, 215-350°C), gasoline, LPG and coke.…”

Section: The Reactor Model For Single Riser or Downermentioning

confidence: 99%

“…A comprehensive 2D reactor model incorporating hydrodynamics, mass balance, energy balance, and a 4-lump/14-lump kinetic model have been successfully established to simulate the riser-and downer-based FCC processes in our earlier work [28]. The established model captured the key characteristics of the gas-solid reacting flows in the riser and downer, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Downer‐to‐Riser Coupling Technique for Petroleum Refining

Cheng

2009

Chem Eng & Technol

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Many recent developments in the fluid catalytic cracking (FCC) technique have focused on achieving cleaner gasoline with less olefins and maximizing light olefins such as propylene. A coupled high-density downer-to-riser reactor was proposed to utilize the advantages of both downer and riser to improve the gasoline quality and to efficiently control the product distribution. The basic idea is to decompose the complex FCC reactions into two reaction zones with distinct operating conditions. The downer accommodates high-severity operation at the initial stage with the benefit of near plug-flow while the riser is operated at a lower temperature with longer contacting time to promote hydrogen shift reactions. A comprehensive 2D reactor model is presented to predict the reactor performances for different reactor designs. The coupled downer-to-riser reactor design was found to have more light olefins and cleaner gasoline than the conventional riser and the coupled riser-to-riser reactor design.

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Numerical Analysis of Flash Ironmaking Process in a Newly Proposed Counter-Current Downer

Yang

Shen

et al. 2021

JOM

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A counter-current downer is proposed as a new structure to improve the flash ironmaking technology (FIT). A computational fluid dynamics (CFD) model was established to predict the dilute gas-particle reacting flow, and a coreannulus structure was observed. Furthermore, counter-current and cocurrent downers have been compared in similar conditions. As a result, reduced iron of the counter-current downer had a higher reduction degree (99.8%) than that of the cocurrent downer (70.1%). The first two reaction steps (Fe 2 O 3 fi Fe 3 O 4 and F 3 O 4 fi FeO) were swift, while the subsequent step (FeO fi Fe) in the counter-current downer showed a significant difference due to the preponderant reduction potential and temperature. Different gas velocities (0.167-0.667 m/s) were also investigated, and the high-speed gas flow brought more particles with decreasing metal yield from 89.3% to 27.5%. However, more gas amounts always led to a higher reduction degree separately of captured and escaped particles.

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Understanding Riser and Downer Based Fluid Catalytic Cracking Processes by a Comprehensive Two-Dimensional Reactor Model

Cited by 23 publications

References 41 publications

Parametric Sensitivity Studies in a Commercial FCC Unit

Parametric Sensitivity Studies in a Commercial FCC Unit

Downer‐to‐Riser Coupling Technique for Petroleum Refining

Numerical Analysis of Flash Ironmaking Process in a Newly Proposed Counter-Current Downer

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