Simulation and experimental study of gas-phase diffusion coefficient of selenium dioxide

Area of Science:

• Environmental Science
• Chemical Engineering
• Physical Chemistry

Background:

• Coal-fired power plants release selenium pollutants, necessitating effective removal strategies.
• Wet flue gas desulfurization systems are crucial for mitigating selenium emissions.
• Understanding selenium pollutant behavior, specifically the gas-phase diffusion of selenium dioxide (SeO2), is vital for optimizing removal processes.

Purpose of the Study:

• To determine the gas-phase diffusion coefficients of SeO2 in flue gas.
• To validate theoretical calculations with experimental measurements.
• To improve the accuracy of selenium removal models in desulfurization systems.

Main Methods:

• Molecular dynamics simulations were employed for theoretical calculations of SeO2 gas-phase diffusion coefficients.
• A self-developed testing device measured SeO2 gas-phase diffusion coefficients between 393 K and 433 K.
• Fuller's formula was used to correct diffusion coefficients for binary and ternary gas mixtures.
• A single-droplet absorption model was constructed and validated.

Main Results:

• Molecular dynamics simulations accurately predicted SeO2 gas-phase diffusion coefficients.
• Experimental measurements validated the simulation results.
• Corrected diffusion coefficients significantly improved the accuracy of the single-droplet absorption model, reducing errors from 8.09% to 1.96%.

Conclusions:

• The study provides crucial gas-phase diffusion coefficient data for SeO2 in the low-temperature range relevant to coal-fired flue gas.
• This data is essential for developing more effective selenium migration mechanisms and control technologies.
• Improved model accuracy aids in optimizing wet flue gas desulfurization processes for reduced selenium emissions.