(55g) Gas-Solid Flow Pattern Analysis in the Riser of Rfcc Process Using CPFD Simulation

Gas-solid flow pattern analysis in the riser of RFCC
process using CPFD simulation

Hyungtae Cho^a, Bumjoon Cha^a,Sungwon Kim^b, Jaewook Ryu^b, Junghwan Kim^b, Il Moon^a,*

^aDepartment of Chemical and Biomolecular Engineering, Yonsei
University, 50 Yonsei-ro, Seodaemun-gu,
Seoul 120-749, Korea

^bSK Innovation Global Technology,
325 Exporo, Yuseong-gu, Daejeon 305-712, Korea

One
of the main problems associated with reactors in commercial Residue Fluidized
Catalytic Cracking (RFCC) process is that each of six outlets of the riser has
different particle mass flow rates due to uneven distribution particle flow. This
problem makes catalyst loss. High conversion of cracking reaction requires uniform
catalyst distribution in the riser. The riser termination device (RTD) is
installed to achieve rapid separation between catalysts and product gas. RTD is
composed of six close-coupled cyclone sets at the top of riser. This study
focuses on the analysis of flow pattern of catalysts from the riser to the
cyclone sets. The cracking reaction is taken into account in the simulation
scheme and its conversion is evaluated in the riser by employing multiphase-particle
in cell (MP-PIC) method, one of computational particle fluid dynamics (CPFD)
methodologies. It applies both a stochastic particle model and Lagrangian method for particle phase, and Eulerian method for fluid phase, respectively. Figures 1
represents, for 30 seconds, particle flow patterns of the riser comprising six
outlets. Macroscopically steady state is reached at 1.5 seconds as shown in Figure
1. Figure 2 shows six different outlet particle mass flow rates over a range between
117.7 kg/s and 122.4 kg/s. A high particle mass flow rate represents a high
solid-gas ratio loaded to cyclones; Figure 2 reveals significant deviations of
the ratios from its even distribution. This has an adverse effect on the
cyclone efficiency, resulting in severe loss of catalysts. So,
this article confirm industrial problem such as uneven distribution of particle
from the riser to the cyclone.

Figure  SEQ Figure \* ARABIC 1. The
particle flow pattern in the riser (a) velocity magnitude and (b) volume
fraction

Figure  SEQ Figure \* ARABIC 2. Mass
flow rate of particle vs. the riser outlet location.

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