Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Slug Characteristics in a Bubbling Fluidized Bed Reactor for Polymerization Reaction

기포유동층 고분자 중합 반응기에서의 슬러그 특성

  • Go, Eun Sol (Department of Mineral Resources Energy Engineering, Jeonbuk National University) ;
  • Kang, Seo Yeong (Department of Mineral Resources Energy Engineering, Jeonbuk National University) ;
  • Seo, Su Been (Department of Mineral Resources Energy Engineering, Jeonbuk National University) ;
  • Kim, Hyung Woo (Department of Mineral Resources Energy Engineering, Jeonbuk National University) ;
  • Lee, See Hoon (Department of Mineral Resources Energy Engineering, Jeonbuk National University)
  • 고은솔 (전북대학교 자원에너지공학과) ;
  • 강서영 (전북대학교 자원에너지공학과) ;
  • 서수빈 (전북대학교 자원에너지공학과) ;
  • 김형우 (전북대학교 자원에너지공학과) ;
  • 이시훈 (전북대학교 자원에너지공학과)
  • Received : 2020.04.16
  • Accepted : 2020.05.30
  • Published : 2020.11.01
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Abstract

Fluidization processes in which solid particles vividly move like gas or liquid have been widely used in various industrial sectors, such as thermochemical energy conversion and polymerization processes for general purpose polymer resins. One of the general purpose polymer resins, LLDPE(Linear low-density polyethylene) resins have been produced in bubbling fluidized bed processes in the world. In a bubbling fluidization polymerization reactors, LLDPE particles with relatively larger particle size and low density are fluidized by hydrogen gas for polymerization reaction. Though LLDPE polymerization reactors are one of bubbling fluidization processes, slugs that have negative impact for reaction exist or occur in these processes. Therefore, the fluidization state of LLDPE particles was investigated in a simulation model similar to a pilot-scale polymerization reactor (0.38 m l.D., 4.4 m High). In particular, the effect of gas velocity (0.45-1.2 m/s), solid density (900-199 kg/㎥), solid sphericity (0.5-1.0), and average particle size (120-1230 ㎛), on bed height and fluidization state were measured by using a CPFD(Computational particle-fluid dynamics) method. With CPFD analysis, the occurrence of a flat slug was visualized. Also, the change in particle properties, such as particle density, sphericity, and size, could reduce the occurrence of slug and bed expansion.

고체 입자들이 유체처럼 움직이는 유동층 공정은 에너지 전환 공정뿐만 아니라 범용 고분자 수지의 생산 공정에도 이용되고 있다. 범용 고분자 수지 중의 하나인 LLDPE(Linear low density polyethylene)도 기포 유동층 공정을 통해 전세계에서 생산되고 있다. 입자 크기에 비해 밀도가 낮은 LLDPE 입자들은 고분자 중합 반응을 위해 공급되는 수소에 의해서 유동화된다. 그러나 LLDPE 생산 공정은 기포유동층 공정임에도 불구하고 발생한 슬러그로 인하여 반응에 영향을 끼쳐 공정의 효율 저하를 불러올 수 있다. 이에 본 연구에서는 상용 고분자 반응기를 모사한 pilot 규모의 고분자 합성 반응기(0.38 m l.D., 4.4 m High)와 동일한 시뮬레이션 모델을 구축하여 LLDPE 입자의 유동화 상태를 고찰하였다. 특히 기체 유속(0.45-1.2 m/s), 고체 입자 밀도(900-1900 kg/㎥), 입자 구형도(0.5-1.0), 입자 크기(120-1230 ㎛)의 변화에 따른 슬러그 특성을 세밀하게 고찰하기 위하여 전산입자유체해석(Computational particle-fluid dynamics, CPFD)을 이용하였다. CPFD를 통해서 일부 실험자들만 고찰할 수 있었던 flat slug의 발생을 시각적으로 구현하였으며 밀도, 구형도, 크기 등의 고체의 물리적 특성을 변화시킴에 따라 슬러그 발생을 저감시킬 수 있음을 확인하였다.

Keywords

References

  1. Lee, S. H., Lee, T. H., Jung, S. M. and Lee, J. M., "Economic Analysis of a 600 mwe Ultra Supercritical Circulating Fluidized Power Plant Based on Coal Tax and Biomass co-combustion Plans," Renew. Energy, 138, 121-127(2019). https://doi.org/10.1016/j.renene.2019.01.074
  2. Gwak, Y. R., Kim, Y. B., Gwak, I. S. and Lee, S. H., "Economic Evaluation of Synthetic Ethanol Production by Using Domestic Biowastes and Coal Mixture," Fuel, 213, 115-122(2018). https://doi.org/10.1016/j.fuel.2017.10.101
  3. Kim, Y. B., Gwak, Y. R., Keel, S. I., Yun, J. H., Lee, S. H., "Direct Desulfurization of Limestones Under Oxy-circulating Fluidized Bed Combustion Conditions," Che. Eng. J., 377, 119650 (2019). https://doi.org/10.1016/j.cej.2018.08.036
  4. Pham, H. H., Lim, Y. I., Han, S. G., Lim, B. S., Ko, H. S., "Hydrodynamics and Design of Gas Distributor in Large-scale AmineAbsorbers Using Computational Fluid Dynamics," Korean J. Chem. Eng., 35, 1073-1082(2018). https://doi.org/10.1007/s11814-018-0006-z
  5. Lee, D. Y., Ryu, H. J., Shun D. W., Bae, D. H. and Baek, J. I., "Effect of Solid Residence Time on $CO_2$ Selectivity in a Semicontinuous Chemical Looping Combustor," Korean J. Chem. Eng., 35, 1257-1262(2018). https://doi.org/10.1007/s11814-018-0042-8
  6. Mendoza, J. A. and Hwang, S. W., "Tubular Reactor Design for the Oxidative Dehydrogenation of Butene Using Computational Fluid Dynamics (CFD) Modeling," Korean J. Chem. Eng., 35, 2157-2163(2018). https://doi.org/10.1007/s11814-018-0143-4
  7. Lee, S. H., Kim, D. W., Lee, J. M. and Bae, Y. C., "Evaluation of Limestone for in-situ Desulfurization in CFB boilers," Korean Chem. Eng. Res., 57, 853-860(2019). https://doi.org/10.9713/kcer.2019.57.6.853
  8. Lee, S. H., "Development of a Hybrid process for Energy Production via Solar Thermo-chemical Conversion," New & Information for Chemical Engineers, 37, 200-206 (2019).
  9. Almendros-Ibanez, J. A., Fernandez-Torrijos, M., Diaz-Heras, M., Belmonte, J. F. and Sobrino, C., "A Review of Solar Thermal Energy Storage in Beds of Particles: Packed and Fluidized Beds," Solar Energy, https://doi.org/10.1016/j.solener.2018.05.047
  10. Liu, T., Liu, Q., Lei, J. and Sui, J., "A New Solar Hybrid Clean Fuel-fired Distributed Energy System with Solar Thermochemcial Conversion," J. Clean. Prod., 213, 1011-1023(2019). https://doi.org/10.1016/j.jclepro.2018.12.193
  11. Kim, Y. B., Kang, S. Y., Seo, S. B., Keel, S. I., Yun, J. H. and Lee, S. H., "The Attrition and Calcination Characteristics of Domestic Limestones for in-situ Desulfurization in Circulating Fluidized Bed Boilers," Korean Chem. Eng. Res., 57, 687-694(2019). https://doi.org/10.9713/kcer.2019.57.5.687
  12. Lee, S. H., Lee, D. H. and Kim, S. D., "Slug Characteristics of Polymer Particles in a Fluidized Bed with Different Distributors," Korean J. Chem. Eng., 18, 387-391(2001). https://doi.org/10.1007/BF02699183
  13. Lim, J. H., Bae, K., Shin, J. H., Lee, D. H., Han, J. H. and Lee, D. H., "CPFD Simulation of Bubble Flow in a Bubbling Fluidized Bed with Shroud Nozzle Distributor and Vertical Internal," Korean Chem. Eng. Res., 54, 678-686(2016). https://doi.org/10.9713/kcer.2016.54.5.678
  14. Wei, L., Lu, Y., Zhu, J., Jiang, G., Hu, J. and Teng, H., "Effect of Cohesive Powders on Pressure Fluctuation Characteristics of Binary Gas-solid Fliudized Bed," Korean J. Chem. Eng., 35, 2117-2126(2018). https://doi.org/10.1007/s11814-018-0115-8
  15. Ramirez, E., Finney, C., Pannala, S., Daw, C. S., Halow, J. and Xiong, Q., "Computational Study of the Bubbling-to-slugging Transition in a Laboratory-scale Fluidized Bed," Chem. Eng. J., 308, 544-556(2017). https://doi.org/10.1016/j.cej.2016.08.113
  16. Amornsirirat, C., Chalermsinsuwan, B., Mekasut, L., Kuchonthara, P. and Piumsomboon, P., "Experiment and 3D Simulation of Slugging Regime in a Circulating Fluidized Bed," Korean J. Chem. Eng., 28, 686-696(2011). https://doi.org/10.1007/s11814-010-0407-0
  17. Salehi-Asl, M., Azhgan, S. and Movahedirad, S., "Some General Aspects of a Gas-solid Fluidized Bed Using Digital Image Analysis," Korean J. Chem. Eng., 35, 613-620(2018). https://doi.org/10.1007/s11814-017-0291-y
  18. Liu, H., Cattolica, R. J. and Seiser, R., "Operating Parameter Effects on the Solids Circulation Rate in the CFD Simulation of a Dual Fluidized-bed Gasification System," Chem. Eng. Sci., 169, 235-245(2017). https://doi.org/10.1016/j.ces.2016.11.040
  19. Lim, J. H. and Lee, D. H., "Two- and Three-dimensional Analysis on the Bubble Flow Characteristics Using CPFD Simulation," Korean Chem. Eng. Res., 55, 698-703(2017). https://doi.org/10.9713/kcer.2017.55.5.698
  20. Lim, J. H., Bae, K., Shin J. H., Kim, J. H., Lee, D. H., Han, J. H. and Lee, D. H., "Effect of Particle-particle Interaction on the Bed Pressure Drop and Bubble Flow by Computational Particlefluid Dynamics Simulation of Bubbling Fluidized Beds with Shroud Nozzle," Powder Technol., 288, 315-323(2016). https://doi.org/10.1016/j.powtec.2015.11.017
  21. Kunii D. and Levenspiel, O., "Fluidization Engineering," Butterworth-Heinemann, Soneham, USA(1991).
  22. Brid, R. B. and Stewart, W. E., Transport Phenomena, Wiley & Sons, Inc. Newyork, USA(2002).
  23. Ryu, H. J., Choi, J. H., Kim, S. D. and Son, J. E., "Slug Characteristics in Gas Fluidized Beds 1. Minimum Slugging Velocity and Slug Frequency," Korean Chem. Eng. Res., 39, 579-589 (2001).
  24. Ryu, H. J., Choi, J. H., Kim, S. D. and Son, J. E., "Slug Characteristics in Gas Fluidized Beds 2. Slug Length and Slug Rising Velocity," Korean Chem. Eng. Res., 39, 590-599(2001).