Adsorption of SO2 from sintering flue gas by alkali modified fly ash in electrostatic precipitator

ABSTRACT

In this study, fly ash was modified with NaOH and Ca(OH)₂ and discussed the feasibility of its adsorption of SO₂ from flue gas in electrostatic precipitator (ESP). The optimal modification conditions were determined by comparing the changes of SO₂ adsorption performance of different modified fly ashes in flue gas. The effect of modification and adsorption of SO₂ before and after on the electrical conductivity of fly ash was investigated by testing the specific resistance characteristics. The results showed that when the solid–liquid ratio was 1:5 and the modification time was 90 min, the Ca(OH)₂ modified fly ash has the best adsorption capacity for SO₂ in flue gas, and the adsorption capacity of SO₂ was 31.44 mg/g. Compared with the raw fly ash, the adsorption capacity increased by 141.85%. The modified fly ash has better conductivity than that before modification, and the peak-specific resistance can be reduced by two orders of magnitude. After SO₂ adsorption, the specific resistance of alkali modified fly ash was increased, but it was still lower than that of the raw fly ash, which was favorable to be removed in the dust removal stage.

KEYWORDS:

• Fly ash
• alkali modification
• SO₂ adsorption
• specific resistance

Acknowledgments

This work was supported by the Natural Science Foundation of Hebei Province [grant number B2019502067] and the Fundamental Research Funds for the Central Universities [grant number 2020MS152].

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author https://ese.ncepu.edu.cn/szdw/hgdk/71842a3629164d7d814fa000d1d1d946.htm.

Statement of novelty

Low-temperature corrosion of electrostatic precipitator is a serious problem in the treatment of sintering flue gas. NaOH and Ca(OH)2 were used to modify fly ash, so that the modified fly ash can react with SO2 in flue gas and avoid the corrosion of dust collector and other equipment. It is proved that the alkali modified fly ash is feasible to adsorb SO2 from flue gas, and the modified fly ash has good specific resistance characteristics, which can achieve “Treat waste with waste,” and has good application prospects for air pollution control.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/01496395.2023.2180392

Additional information

Funding

The work was supported by the Natural Science Foundation of Hebei Province [B2019502067]