PM₁₀ emissions from industrial coal-fired chain-grate boilers

Highlights

PM in submicron mode emitted from raw coal burning contribute to 33 % of PM₁₀.

PM in submicron mode from briquette coal burning contribute to 86 % of PM₁₀.

Collection efficiency of muticlones and scrubbers is 34% for submicron particle.

Peak of submicron mode in normal operation period is larger than start-up period.

Abstract

Industrial coal-fired boiler is an important air pollutant emission source in China. The chain-grate boiler is the most extensively used type of industrial coal-fired boiler. An electrical low-pressure impactor, and a Dekati^® Low Pressure Impactor were applied to determine mass and number size distributions of PM₁₀ at the inlet and the outlet of the particulate emission control devices at six coal-fired chain-grate boilers. The mass size distribution of PM₁₀ generated from coal-fired chain-grate boilers generally displays a bimodal distribution that contains a submicron mode and a coarse mode. The PM in the submicron mode for burning with raw coal contributes to 33%±10 % of PM₁₀ emissions, much higher than those for pulverized boilers. And the PM in the submicron mode for burning with briquette contributes up to 86 % of PM₁₀ emissions. Multiclones and scrubbers are not efficient for controlling PM₁₀ emission. Their average collection efficiencies for sub-micron particle and super-micron particle are 34% and 78%, respectively. Operating conditions of industrial steam boilers have influence on PM generation. Peak of the submicron mode during normal operation period is larger than the start-up period.

Graphical abstract

Keywords

coal-fired chain-grate boiler / PM₁₀ / size distribution / particulate emission control devices / size-dependent collection efficiency

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Acknowledgements

This study was supported by the National Natural Science Foundation of China (Grant Nos. 41275121 and 41575119) and the National Key Basic Research and Development Program of China (No. 2013CB228505) and Beijing Municipal Science & Technology Commission (Grant No. Z161100000716004).

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2017 Higher Education Press and Springer–Verlag Berlin Heidelberg