Articles | Volume 16, issue 11
Atmos. Chem. Phys., 16, 7485–7496, 2016
Atmos. Chem. Phys., 16, 7485–7496, 2016

Research article 15 Jun 2016

Research article | 15 Jun 2016

New particle formation in the fresh flue-gas plume from a coal-fired power plant: effect of flue-gas cleaning

Fanni Mylläri1, Eija Asmi2, Tatu Anttila1, Erkka Saukko1, Ville Vakkari2, Liisa Pirjola3, Risto Hillamo2, Tuomas Laurila2, Anna Häyrinen4, Jani Rautiainen4, Heikki Lihavainen2, Ewan O'Connor2, Ville Niemelä5, Jorma Keskinen1, Miikka Dal Maso1, and Topi Rönkkö1 Fanni Mylläri et al.
  • 1Department of Physics, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland
  • 2Atmospheric Composition Research, Finnish Meteorological Institute, 00560, Helsinki, Finland
  • 3Department of Technology, Metropolia University of Applied Sciences, 00180, Helsinki, Finland
  • 4Helen Oy, 00090 Helen, Helsinki, Finland
  • 5Dekati Ltd., Tykkitie 1, 36240 Kangasala, Finland

Abstract. Atmospheric emissions, including particle number and size distribution, from a 726 MWth coal-fired power plant were studied experimentally from a power plant stack and flue-gas plume dispersing in the atmosphere. Experiments were conducted under two different flue-gas cleaning conditions. The results were utilized in a plume dispersion and dilution model taking into account particle formation precursor (H2SO4 resulted from the oxidation of emitted SO2) and assessment related to nucleation rates. The experiments showed that the primary emissions of particles and SO2 were effectively reduced by flue-gas desulfurization and fabric filters, especially the emissions of particles smaller than 200 nm in diameter. Primary pollutant concentrations reached background levels in 200–300 s. However, the atmospheric measurements indicated that new particles larger than 2.5 nm are formed in the flue-gas plume, even in the very early phases of atmospheric ageing. The effective number emission of nucleated particles were several orders of magnitude higher than the primary particle emission. Modelling studies indicate that regardless of continuing dilution of the flue gas, nucleation precursor (H2SO4 from SO2 oxidation) concentrations remain relatively constant. In addition, results indicate that flue-gas nucleation is more efficient than predicted by atmospheric aerosol modelling. In particular, the observation of the new particle formation with rather low flue-gas SO2 concentrations changes the current understanding of the air quality effects of coal combustion. The results can be used to evaluate optimal ways to achieve better air quality, particularly in polluted areas like India and China.

Short summary
The primary emissions of a coal-fired power plant were highly affected by the flue-gas cleaning technologies. The primary emission results were used as input values for a Gaussian plume model and the model correlated well with the atmospheric measurements from the flue-gas plume. Concentrations of newly formed particles in the flue gas plume were higher than the primary particle concentration, and thus the source of particle-forming precursors should be characterized in more detail.
Final-revised paper