Go Eun Sol, Kim Beom-Sik, Ling Jester Lih Jie, Oh Seung Seok, Park Hyun Jun, Lee See Hoon
Department of Environment and Energy, Jeonbuk National University, 567, Baekje-daero, Jeonju-si, jeollabuk-do, 54896, Republic of Korea.
Hydrogen Research Center, Research Institute of Industrial Science and Technology, 67, Cheongam-ro, Nam-gu, Pohang-si, Gyeongsangbuk-do, 37673, Republic of Korea.
Environ Res. 2023 May 15;225:115582. doi: 10.1016/j.envres.2023.115582. Epub 2023 Feb 27.
Within circulating fluidized bed (CFB) processes, gas and solid behaviors are mutually affected by operating conditions. Therefore, understanding the behaviors of gas and solid materials inside CFB processes is required for designing and operating those processes. In addition, in order to minimize the environmental impact, modeling to reduce pollutants such as SO emitted from those processes is essential, and simulation reproduction is necessary for optimization, but little is known. In this study, the gas and solid behaviors in a pilot-scale circulating fluidized bed combustor were investigated by using computational particle fluid dynamics (CPFD) numerical simulation based on the multiphase particle-in-cell (MP-PIC) method under oxy-fuel combustion conditions. In particular, the combustion and in-situ desulfurization reactions simultaneously were considered in this CPFD model. Effect of fluidization number (U/U) was investigated through the comparison of particle circulation rates with regards to the loop seal flux plane and bed height in the standpipe. In addition, the effects of parameters (temperature, Ca/S molar ratio, and particle size distribution), sensitive indicators for the desulfurization efficiency of limestone, were confirmed. Based on the cycle of the thermodynamic equilibrium curve of limestone, it is suggested that direct and indirect desulfurization occur simultaneously under different operating conditions in CFB, creating an environment in which various reactions other than desulfurization can occur. Addition of the reaction equations (i.e., porosity, diffusion) to the established simple model minimizes uncertainty in the results. Furthermore, the model can be utilized to optimize in-situ desulfurization under oxy-CFB operating conditions.
在循环流化床（CFB）工艺中，气体和固体行为会受到操作条件的相互影响。因此，设计和操作这些工艺需要了解CFB工艺内部气体和固体材料的行为。此外，为了将环境影响降至最低，对减少这些工艺中排放的诸如SO等污染物进行建模至关重要，并且为了优化需要进行模拟再现，但目前对此了解甚少。在本研究中，基于多相单元内粒子（MP-PIC）方法，采用计算粒子流体动力学（CPFD）数值模拟，对中试规模循环流化床燃烧器在富氧燃烧条件下的气体和固体行为进行了研究。特别是，在该CPFD模型中同时考虑了燃烧和原位脱硫反应。通过比较立管中回路密封通量平面和床层高度处的颗粒循环速率，研究了流化数（U/U）的影响。此外，还确定了石灰石脱硫效率的敏感指标参数（温度、钙硫摩尔比和粒度分布）的影响。基于石灰石热力学平衡曲线的循环，表明在CFB的不同操作条件下，直接脱硫和间接脱硫同时发生，创造了一个除脱硫之外还能发生各种反应的环境。在已建立的简单模型中加入反应方程（即孔隙率、扩散）可将结果的不确定性降至最低。此外，该模型可用于优化富氧CFB操作条件下的原位脱硫。
