Coupling of alkaline and mechanical modified fly ash for HCl and SO2 removal in the municipal solid waste incineration plant

In this study, fly ash was modified by ball milling through coupling alkaline and mechanical to achieve the reuse of fly ash. The adsorption capacity of fly ash for acidic gases was improved in experiments using simple ball milling. Under the optimal ball milling conditions with coupled NaOH, the desulfurization efficiency can reach 100% and the dechlorination efficiency can be maintained above 90% for the first 100 s of the experiment. Different characterizations show that the ball milling process increases the specific surface area of fly ash, which makes NaOH adhere uniformly to the surface of fly ash particles in an amorphous structure and improves the adsorption effect of the fly ash on acid gases. In addition, experiments with different gas parameters proved that increased temperature, increase of the flue gas flow rate, and increase of the acidic gas concentration in flue gas all lead to the decrease of the modified fly ash's deacidification efficiency. This provides a reference for engineering applications of modified fly ash under different working conditions. In summary, a comprehensive technical route of "fly ash collection - online modification - timely injection" is proposed in the municipal solid waste incineration (MSWI) plant.