Sulfation performance of CaO under circulating fluidized bed combustion-like condition
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Sulfation performance of CaO under circulating fluidized bed combustion‑like condition Y. J. Bai1,2 · M. Q. Chen1,2 · Q. H. Li3 · Y. W. Huang1,2 Received: 27 August 2019 / Accepted: 16 May 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract As a major air pollutant, S O2 has negative effect on the human health and environment. The desulfurization characteristics of two CaO samples (commercial one and the other one calcined from C aCO3) with high purity were examined by a thermo-gravimetric analyzer under circulating fluidized bed combustion-like condition. The influences of SO2 concentration (1000–4000 ppm), CO2 concentration (0–45%) and temperatures (800–950 °C) on the sulfation conversion degree of CaO samples were addressed, and sulfation kinetic parameters for the two samples were estimated based on the unreacted shrinking core model. The sulfation conversion degree of CaO calcined from CaCO3 at 900 °C and 2000 ppm SO2 was 68% higher than the commercial CaO. The sulfation conversion degree for the commercial CaO at 950 °C with 2000 ppm SO2 was one time higher than at 800 °C, and the sulfation conversion degree for the sample calcined from CaCO3 at 950 °C increased by about 31% compared to that at 800 °C. The calcium conversion degree of the sample calcined from C aCO3 was 0.59 in the absence of CO2, and the conversion degree with the CO2 concentration of 45% reduced by about 31%. The sulfation kinetics of two samples were appropriately described by the shrinking unreacted core model. The sample calcined from C aCO3 had a better sulfation activity than the commercial CaO. Keywords CaO · CaCO3 · SO2 · Sulfation · Kinetics · Circulating fluidized bed Abbreviation b Stoichiometric coefficient A, B Characteristic time in Eqs. (4a) and (4b) (min) A1, B1 Revise factors of time in Eqs. (4a) and (4b) (min) CA0 SO2 concentration (mol mL−1) CS0 CaO concentration (mol mL−1) D0 Pre-exponential factor of the product layer diffusion reaction (cm2 min−1)
* M. Q. Chen [email protected] * Q. H. Li [email protected] 1
Institute of Thermal Engineering, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, People’s Republic of China
Beijing Key Laboratory of Flow and Heat Transfer of Phase Changing in Micro and Small Scale, Beijing 100044, People’s Republic of China
2
3
Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, People’s Republic of China
Ds Effective diffusivity of reactants in the product layer (cm2 min−1) Ea Activation energy for chemical reaction stage (kJ mol−1) Ep Activation energy for product layer diffusion (kJ mol−1) Gfp(x) Function defined by Eq. (6a) k Rate constant of the surface reaction (cm min−1) k0 Pre-exponential factor of the surface reaction (cm min−1) m Mass (mg) M Molar mass (g mol−1) Pfp(x) Function defined by Eq. (6b) R General gas constant (J mol−1 K−1) Rp Original rad
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