Browse > Article
http://dx.doi.org/10.9713/kcer.2020.58.4.642

Analysis of Fluidization in a Fluidized Bed External Heat Exchanger using Barracuda Simulation  

Lee, Jongmin (KEPCO Research Institute)
Kim, Dongwon (KEPCO Research Institute)
Park, Kyoungil (KEPCO Research Institute)
Lee, Gyuhwa (KEPCO Research Institute)
Publication Information
Korean Chemical Engineering Research / v.58, no.4, 2020 , pp. 642-650 More about this Journal
Abstract
In general, the circulation path of the fluidized particles in a CFB (Circulating Fluidized Bed) boiler is such that the particles entrained from a combustor are collected by a cyclone and recirculated to the combustor via a sealpot which is one of non-mechanical valves. However, when a fluidized bed heat exchanger (FBHE) is installed to additionally absorb heat from the fluidized particles, some particles in the sealpot pass through the FBHE and then flow into the combustor. At this time, in the FBHE operated in the bubbling fluidization regime, if the heat flow is not evenly distributed by poor mixing of the hot particles (800~950 ℃) flowing in from the sealpot, the heat exchanger tubes would be locally heated and then damaged, and the agglomeration of particles could also occur by formation of hot spot. This may affect the stable operation of the circulating fluidized bed. In this study, the unevenness of heat flow arising from structural problems of the FBHE of the domestic D-CFB boiler was found through the operating data analysis and the CPFD (Computational Particle Fluid Dynamics) simulation using Barracuda VR. Actually, the temperature of the heat exchanger tubes in the FBHE showed the closest correlation with the change in particle temperature of the sealpot. It was also found that the non-uniformity of the heat flow was caused by channeling of hot particles flowing in from the sealpot. However, it was difficult to eliminate the non-uniformity even though the fluidizing velocity of the FBHE was increased enough to fluidize hot particles vigorously. When the premixing zone for hot particles flowing in from the sealpot is installed and when the structure is changed through the symmetrization of the FBHE discharge line for particles reflowing into the combustor, the particle mixing and the uniformity of heat flow were found to be increased considerably. Therefore, it could be suggested that the structural modification of the FBHE, related to premixing and symmetric flow of hot particles, is an alternative to reduce the non-uniformity of the heat flow and to minimize the poor particle mixing.
Keywords
Fluidized bed heat exchanger; Barracuda simulation; Particle mixing; Heat flow;
Citations & Related Records
Times Cited By KSCI : 6  (Citation Analysis)
연도 인용수 순위
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).   DOI
2 IEA-FBC TCP, "Developments in Fluiidzied Bed Conversion During 2011-2016," Country Report, edited by Jongmin Lee, KEPCO RI, Korea(2017).
3 Lee, S. H. and Lee, J. M., "Introduction and Current Status of Ultra Supercritical Circulating Fluidized Bed Boiler," KEPCO Journal, 2(2), 211-222(2016).
4 Lee, J. M., Kim, J. S. and Kim, J. J., "Evaluation of the 200MWe Tonghae CFB Boiler Performance with Cyclone Modification," Energy, 28, 111-118(2003).
5 Lee, S. H., Lee, J. M., Kim, J. S., Choi, J. H. and Kim, S. D., "Combustion Characteristics of Anthracite Coal in the D CFB Boiler," Korean Chem. Eng. Res., 38(4), 516-522(2000).
6 Rogalev, N., "A Survey of State of Art Development of Coal Fired Steam Turbine Power Plant Based on Advanced Ultrasupercritical Steam Technology," Contemporary Engineering Science, 7(34), 1807-1825(2014).   DOI
7 Wang, L., Yang, D. Shen, Z., Mao, K. and Long, J., "Thermalhydraulic Calculation and Analysis of a 600 MW Supercritical Circulating Fluidized Bed Boiler with Annular Furnace," Applied Thermal Engineering, 95, 42-52(2016).   DOI
8 Lee, J. M., Kim, D. W., Park, K. I. and Kim, S. M., "Performance Analysis of Cyclone and Fludized Bed External Heat Exchanger Through Barracuda Simulation," 23th International Conference on FBC, Spring, Korea, 1171-1177(2018).
9 Abbasi, A., Ege, P. E. and Lasa, H., "CPFD Simulation of a Fast Fluidized Bed Steam Coal Gasifier Feeding Section," Chemical Engineering Journal, 174, 341-350(2011).   DOI
10 Clark, S. M. and Snider, D. M. and Fletcher, R. P., "Multiphase Simulation of a Commercial Fluidized Catalytic Cracking Regenerator," AIChE 2012 Annual Meeting, Pittsburgh, Pennsylvania, USA(2012).
11 Williams, A. K., "Industrial Applications of CFD for Clean Coal Plant Design," NETL Workshop on Multiphase Flow Science, August, USA(2013).
12 Ergun, S., "Fluid Flow Through Packed Columns," Chemical Engineering Progress, 48-89(1949).
13 Wang, B. and Yu, A. B., "Numerical Study of the Gas-liquid-solid Flow in Hydrocyclones with Different Configuration of Vortex Finder," Chemical Engineering Journal, 135, 33-42(2008).   DOI
14 Pham, H. H., Lim, Y. I., Han, S. G., Lim, B. S., Ko, H. S., "Hydrodynamics and Design of Gas Distributor in Large-scale Amine Absorbers Using Computational Fluid Dynamics," Korean J. Chem. Eng., 35, 1073-1082(2018).   DOI
15 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).   DOI
16 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).   DOI
17 Wen, C. and Yu, Y., "Mechanics of Fluidization," Chemical Engineering Progress Symposium, 100-111(1966).
18 CPFD Software, LLC, "Agglomeration Model," Barracuda VR Series 15 User Manual, 68-70(2013).