Characteristics of emission and light-absorption of size-segregated carbonaceous aerosol emitted from four types of coal combustion at different combustion temperatures

Coal consumed in domestic cooking and heating in rural areas of China is considered as a major source of air pollution. To efficiently represent the emission of coal burnt for residential living at various combustion regimes, four coal samples are selected for combustion experiments in the simulated air state at three different temperatures in a drop-tube furnace system in this study. Size-segregated particulate matter in flue gas from combustion of the four coal samples at different temperatures were collected by a TISCH-type Andersen eight-stage impact sampler operating synchronously with the furnace system. The emission factors of the particulate matter samples show that OC2 and OC3 are the main carbonaceous products of bituminous coal and lignite combustion. It is also found that the particulate matter from lignite flue gas contains EC1 in a large proportion and a small amount of highly-refractory EC2 and EC3 from bituminous coals. Meanwhile, in order to evaluate the light-absorption of organic carbon in particulate matter, the mass absorption cross efficiency (alpha/rho) is investigated. The clear-sky radiative transfer model shows that BrC emitted from low-temperature burning leads to even positive top-ofatmosphere radiative forcing at surfaces with an albedo of 0.19. In the 300-700 nm spectral band, the simple forcing efficiency (SFE) of particulate matter sampled significantly decreases as combustion temperature and coal maturity increase. The particulate matter presents a high SFE in the range of 0.4-1.1 mu m in terms of particle size.

Automated summary

The study investigated the impact of coal burning for domestic use in rural areas of China on air pollution, focusing on emissions and combustion characteristics. Results showed that bituminous coal and lignite combustion mainly produce OC2 and OC3 as carbonaceous products, with lignite flue gas containing a larger proportion of EC1. Light-absorption of organic carbon in particulate matter was evaluated using mass absorption cross efficiency (alpha/rho), with findings showing a decrease in forcing efficiency with increasing combustion temperature and coal maturity.