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.

REFERENCES (¾ç½Ä È®ÀÎ ÈÄ ¼öÁ¤z¹Á¤)

[1] Sung Won Kim, Ju Wook Lee, Cheol Joong Kim, Jae Suk Koh, Gyung Rok Kim, and Sun Choi, Characteristics of Deposits Formed in Cyclones in Commercial RFCC Reactor. Industrial and Engineering Chemistry Research, 51, 10238-10246 (2012).

[2] Sung Won Kim, Ju Wook Lee, Jae Suk Koh, Gyung Rok Kim, Sun Choi, and Ik Sang Yoo, Formation and Characterization of Deposits in Cyclone Dipleg of a Commercial Residue Fluid Catalytic Cracking Reactor, Industrial and Engineering Chemistry Research, 51, 14279-14288 (2012).

[3] M.J. Andrews and P.J. O'Rourke, The Multiphase Particle-In-Cell (MP-PIC) method for dense particulate flows, International Journal of Multiphase Flow, 22, 379-402 (1996)

[4] V. A. Danilov, Jongkoo Lim, and Il Moon, Three-dimensional two-phase CFD model for DMFC design, Journal of Power Source, 162(2), 992-1002 (2006).

[5] Xinglong Zhou, Leming Cheng, , Qinhui Wang, Zhongyang Luo and Kefa Cen, Non-uniform distribution of gas–solid flow through six parallel cyclones in a CFB system: An experimental study, Particuology, 10(2), 170– 175 (2012)