Fire (Feb 2023)
Nitrated Phenols and PM<sub>2.5</sub> Reduction of High-Sodium Coal Combustion by Diatomite Addition in a Typical Residential Stove
Abstract
Nitrated phenols from residential combustion aggravate the greenhouse effect and endanger human health. To search for an ideal residential fuel which produces low nitrated phenols, high-sodium coal, conventionally used in coal-fired power plants, has been used for residential combustion considering that the construction of civil stoves makes it easy to deal with slag fouling. In this study, we investigated pollutant emissions by comparing those produced by Jinyu coal, high-sodium coal and high-sodium coal with 5% diatomite. It was found that high-sodium coal mixed with 5% diatomite showed the most desirable nitrated phenols emission factors (EFs) and particle matter (PM) EFs. Originally, high-sodium coal generated more PM EFs because its more easily vaporized composition of sodium (Na) derived from Na compounds in high-sodium coal generated more condensation nuclei of particles. PM2.5 EFs of the high-sodium coal were as high as 3.23 ± 0.11 mg/kJ, 11% more than that of Jingyu coal. However, it had lower EFs of nitrated phenols, whose nitrated phenol EFs in PM2.5 were 2.3 ± 0.2 mg/MJ, remarkably lower than that of Jinyu coal (4.0 ± 0.4 mg/MJ). This can be explained by the fact that high-sodium coal has less intermediate NOx for nitrated phenols generation. However, after 5% diatomite was mixed with high-sodium coal, the nitrated phenols EFs and PM EFs dropped by 60.9% and 53.3%, respectively, during the combustion process. Its abundant silicon (Si) and aluminum (Al) formed a high-melting-point substance with Na. Consequently, considerable pollutant reduction and combustion efficiency promotion were both achieved by 5% diatomite addition to high-sodium coal. It can be concluded that high-sodium coal with 5% diatomite is a promising alternative domestic fuel featuring excellent emission reduction effects, and easy-to-handle slagging in civil stoves.
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