Will ozone-based denitration exacerbate ozone pollution?

Since this technology exists, it should be relatively environmentally friendly

I think so. Ozone cannot be utilized 100% effectively.

Ozone has highly unstable chemical properties and gradually decomposes at room temperature. In air at room temperature, normal pressure, and with an ozone concentration of less than 1%, its half-life of decomposition is around 20 to 30 minutes. As the temperature rises, the decomposition rate increases; when the temperature exceeds 100°C, the decomposition becomes very rapid, and at a temperature of 270°C, it can be immediately converted into oxygen. Ozone decomposes more quickly in water than in air. In an aqueous solution containing impurities, ozone rapidly reverts to the oxygen from which it was formed. Since the ozone denitration process takes place before wet flue gas desulfurization, the reaction temperature is usually above 100°C, and the ozone is further washed by the slurry in the desulfurization tower; as a result, the ozone that has not reacted fully with NO decomposes into oxygen in subsequent processes. Therefore, the amount of ozone released into the atmosphere through the chimney can be considered negligible. 　　However, it is worth noting that the increase in flue gas oxygen content has a slight impact on the conversion of pollutant concentrations. It is recommended that the ozone denitration process utilize advanced spray mixing technology to maximize ozone utilization and enhance mixing intensity, thereby controlling ozone escape.

Oxidative denitration has been banned in Zibo

This is a document issued by the Zibo Environmental Protection Bureau last August, requiring that oxidation-based denitration methods be replaced with SCR or SNCR; the reason was not given, but it is likely that the nitrate pollution generated by oxidation methods is more severe

Can’t SCR and SNCR denitration meet the emission standards?

Currently, SCR can fully meet ultra-low emission standards. SNCR alone does not have a high denitration efficiency, but it is generally used in combination with SCR; by employing the SNCR+SCR combined process, achieving ultra-low emissions is hardly a problem. I think the reason why the ozone denitration method is not allowed to be used is: 1. Once nitrates dissolve in the desulfurization solution, they are difficult to handle ； 2. The addition of ozone may have some impact on emission testing, but most industries now use baseline oxygen, and emission values are converted to those based on baseline oxygen; therefore, this impact has become smaller. 3. After using ozone for denitration, the corrosion of the flue gas duct in the reaction section is also a matter of concern. Additionally, the document in Zibo City prohibiting the use of ozone could not be found later on; it seems that the ban was lifted. However, various regions still remain reluctant to use ozone for denitration.

Indeed, ozone degradation is very effective; the main problem is the increase in total nitrogen in water bodies, and there is yet no effective treatment method for this.