Study on the FCC Process in a Novel Riser−Downer−Coupling Reactor (II):  Simulation and Hot Experiments

Deng, Ruixue; Liu, Huie; Gao, Lei; Wang, Lei; Wei, Fei; Ye, Jin

doi:10.1021/ie0401758

Cited by 11 publications

(8 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Studies on the downer reactor started in the 1990s and there is now a substantial amount of understanding of the flow behaviors in the downer . The downer has a distinct axial flow structure in the downer due to the concurrent gas‐solids flow in the direction of gravity.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Li et al reported the hydrodynamics and reactor performance using a hot model reaction (ozone decomposition) in a downer. Those studies were, however, carried and with low solids circulation rates, less than 200 kg/m 2 s, even though many industrial CFB reactors such as FCC (where solids flux normally ranges from 400 to 1200 kg/m 2 s) are operated at much higher solids circulation rate with higher solids holdup.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A comparison of flow development in high density gas‐solids circulating fluidized bed downer and riser reactors

Wang

Zhu

et al. 2015

AIChE Journal

View full text Add to dashboard Cite

Comparison of flow development in high density downer and riser reactors is experimentally investigated using fluid catalytic cracking particles with very high solids circulation rate up to 700 kg/m2s for the first time. Results show that both axial and radial flow structures are more uniform in downers compared to riser reactors even at very high density conditions, although the solids distribution becomes less uniform in the high density downer. Solids acceleration is much faster in the downer compared to the riser reactor indicating a shorter length of flow development and residence time, which is beneficial to the chemical reactions requiring short contact time and high product selectivity. Slip velocity in risers and downers is also first compared at high density conditions. The slip velocity in the downer is much smaller than in the riser for the same solids holdup indicating less particle aggregation and better gas‐solids contacting in the downer reactors. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1172–1183, 2015

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A comparison of flow development in high density gas‐solids circulating fluidized bed downer and riser reactors

Wang

Zhu

et al. 2015

AIChE Journal

View full text Add to dashboard Cite

show abstract

“…The test results in the industry indicated that the selectivity to desired products could be improved in the coupling reactor as a result of the introduction of the downer part. 12 When the downer was operated as the FCC reactor separately, the yields of gasoline, liquefied petroleum gas (LPG), and propylene were increased by 3.90, 8.14, and 4.30 wt %, respectively, in contrast to a conventional riser. Meanwhile, the diesel oil and dry gas were decreased by 10.48 and 1.83 wt %, respectively.…”

Section: Introductionmentioning

confidence: 99%

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

Cheng

2008

Ind. Eng. Chem. Res.

Self Cite

View full text Add to dashboard Cite

A two-dimensional reactor model incorporating hydrodynamics, mass balance, energy balance, and a 4-lump/ 14-lump kinetic model was established to simulate the riser and downer based fluid catalytic cracking (FCC) processes. The kinetic parameters of the 4-lump kinetic model were re-evaluated from the originally published experimental data for a more reliable description of the FCC process. The 14-lump kinetic model based on a molecular description of cracking and hydrogen transfer reactions was to include more details about the feedstock composition, reaction mechanisms, and the products distribution for a better understanding on the reactor performance for FCC process. This comprehensive model captured the key characteristics of the gas-solid reacting flows in the riser and downer, i.e., the uniformity of flow structures, the distinct backmixing behavior in the riser and downer, and the momentum and energy balances during the complex FCC reactions. The model predictions were first validated against industrial data from several literature sources and found to agree with each other reasonably well. Then, the simulations were carried out to fully understand the different reactor performances of riser and downer in the application of FCC refining processes. It can be concluded that the downer benefits from its advantages of the plug-flow nature and uniform flow structures, tending to have more products in the middle distillates, e.g., gasoline and light olefins, especially under high-severity operations. Better control of the reaction extent for increased selectivity to desired intermediate products would allow the use of downer reactors for the larger-scale practical applications in the FCC process, together with the valuable byproduction of light olefins.

show abstract

“…Until now, many researchers have simulated the fluidized reactions of fluid catalytic cracking, 18,19 ozone decomposition, 20−22 methanol to olefins, 23,24 carbon monoxide oxidation, 25 catalytic combustion of methane, 26 and other processes 6 using the multiscale-or cluster-based mass transfer model and obtained satisfying results, which confirms that it is rational to forecast the mass transfer behavior in consideration of the fluidized structural effect. However, compared with the above numerical studies that mainly focus on the catalytic gasphase reaction, the non-catalytic solid-phase process further involves the variation of the particle diameter and density, the alteration of gas/solid holdup, and the constitution of kinetics and the rate-controlling mechanism, all of which have not been analyzed comprehensively coupled with mass transfer simulation yet.…”

Section: Introductionmentioning

confidence: 80%

CFD Simulation of a Fluid–Solid Non-Catalytic Reaction Based on a Structure-Based Mass Transfer Model: Shrinking Spherical Reaction

Zou

Zhu

Jia

et al. 2020

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

To forecast the mass transfer behavior in consideration of non-catalytic solid reaction characteristics with the shrinking spherical model (SPM), a structure-based mass transfer model taking account of the gas–solid mass exchange within both the emulsion and bubble/interphase phases is built and coupled with computational fluid dynamics (CFD) to predict the carbochlorination of TiO2 with a binary gas–solid phase system. Based on the validation through comparing with the experimental data, the simulation gives a comprehensive understanding and deep analysis of the gas–solid reaction that is helpful for the design and optimization of a non-catalytic fluidized reactor. It is concluded that the fluidized mass transfer process with a heterogeneous flow structure is not only affected by the chemical reaction rate but also dependent on local flow parameters.

show abstract

Study on the FCC Process in a Novel Riser−Downer−Coupling Reactor (II): Simulation and Hot Experiments

Cited by 11 publications

References 19 publications

A comparison of flow development in high density gas‐solids circulating fluidized bed downer and riser reactors

A comparison of flow development in high density gas‐solids circulating fluidized bed downer and riser reactors

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

CFD Simulation of a Fluid–Solid Non-Catalytic Reaction Based on a Structure-Based Mass Transfer Model: Shrinking Spherical Reaction

Contact Info

Product

Resources

About