CFD modeling for NOx absorption accompanying with SO2 in wet flue gas desulfurization scrubber based on gas-phase ozone oxidation

NOx removal performance accompanying with SO2 is investigated in a two-step process containing O3 pre-oxidation of NO and NOx post-absorption in the scrubber of wet flue gas desulfurization (WFGD) unit. Based on EulerianLagrangian framework, a comprehensive CFD model is established to describe the r...

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Bibliographic Details
Published in:Process safety and environmental protection 2022-03, Vol.159, p.685-697
Main Authors: Qu, Jiangyuan, Qi, Nana, Zhang, Kai
Format: Article
Language:English
Subjects:
Absorption
Air pollution control
Chemical composition
Coal-fired power plants
Desulfurization
Desulfurizing
Droplets
Eulerian-Lagrangian model
Flue gas
Flue gas desulfurization
Fluid mechanics
Hydrodynamics
Mass transfer
Nitrogen dioxide
Nitrogen oxides
Oxidation
Oxidation process
Ozone pre-oxidation
pH effects
Pollution control equipment
Scrubbers
Sulfur dioxide
Two-phase flow
Wet flue gas desulfurization
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Summary:NOx removal performance accompanying with SO2 is investigated in a two-step process containing O3 pre-oxidation of NO and NOx post-absorption in the scrubber of wet flue gas desulfurization (WFGD) unit. Based on EulerianLagrangian framework, a comprehensive CFD model is established to describe the reactions of NO2 and N2O5 with S(IV) in droplets coupled with NOx transfer process and hydrodynamics in the scrubber. Taking the WFGD scrubber of 330 MW coal-fired power unit as case study, the results indicate NOx absorption efficiency in scrubber is increased by increasing O3/NO molar ratio from 1.0 to 2.2 and decreasing reaction temperature from 423 K to 363 K in O3 pre-oxidation process. The obtained highest removal efficiency is 85.79% for pH of 5.5 or 96.32% for pH of 9.0 in droplets. NO2 absorption is much slower than N2O5 and more sensitive to chemical compositions in droplets or hydrodynamics in scrubber. The overall mass transfer coefficient (KG) for NO2 is mainly determined by pH and S(IV) concentration in droplets, while the specific interfacial area (a) is largely influenced by gasdroplet hydrodynamics in scrubber. Finally, a correlation is proposed to predict the volumetric mass transfer coefficient (KGa) for NO2 absorption accompanying with SO2 in WFGD scrubber. [Display omitted]
ISSN:0957-5820
1744-3598
DOI:10.1016/j.psep.2022.01.037